Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
  • F02C9/00—Controlling gas-turbine plants; Controlling fuel supply in air- breathing jet-propulsion plants
  • F02C9/48—Control of fuel supply conjointly with another control of the plant
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
  • F02C7/00—Features, components parts, details or accessories, not provided for in, or of interest apart form groups F02C1/00 - F02C6/00; Air intakes for jet-propulsion plants
  • F02C7/22—Fuel supply systems
  • F02C7/236—Fuel delivery systems comprising two or more pumps
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
  • F02C9/00—Controlling gas-turbine plants; Controlling fuel supply in air- breathing jet-propulsion plants
  • F02C9/26—Control of fuel supply
  • F02C9/263—Control of fuel supply by means of fuel metering valves
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02K—JET-PROPULSION PLANTS
  • F02K1/00—Plants characterised by the form or arrangement of the jet pipe or nozzle; Jet pipes or nozzles peculiar thereto
  • F02K1/06—Varying effective area of jet pipe or nozzle
  • F02K1/15—Control or regulation
  • F02K1/16—Control or regulation conjointly with another control
  • F02K1/17—Control or regulation conjointly with another control with control of fuel supply

Definitions

• the invention relates to a fuel supply circuit for an aircraft engine, and more particularly to a fuel supply circuit for supplying the combustion chamber of the engine and for use as a hydraulic fluid for the control of the engine. variable geometry actuators of the motor.
• a fuel supply circuit of an aircraft engine comprises a pumping system consisting of a low pressure pump associated with a high pressure pump.
• the high-pressure pump is generally in the form of a volumetric gear pump whose displacement is fixed and which is driven by the motor via a gearbox or accessory relay box (or again AGB for "Accessories Gear Box”).
• This pump has the function of delivering fuel under high pressure to the combustion chamber injectors and variable geometry engine actuators.
• the delivered fuel flow rate is not adapted to the real needs of the engine at all operating points and exceeds it over a wide range of rotational speed of the engine.
• the fuel flow rate that is not consumed by the fuel system during these rotational speeds of the engine is then recirculated upstream of the high pressure pump. However, this recirculation induces a heating of the fuel and draws mechanical power from the pump which is not useful for engine thrust.
• the high pressure pump preferably operates on a single stage when the flight points require little displacement. In this case, the flow rate of the other pump is completely recirculated while maintaining a low pressure loading, thus reducing the mechanical power. taken from this floor.
• the second pump is activated.
• US 7,234,293 discloses an example of a double stage high pressure pump.
• this document describes a switching system between one and two-stage configurations based on a modification of the control valve which is double recirculation section (one for each stage of the high pressure pump).
• this type of switching introduces disturbances in the metered flow of fuel which are particularly detrimental to the accuracy of this metered flow.
• the main object of the present invention is thus to overcome such disadvantages by proposing a switching system for a double-stage high-pressure pump making it possible to switch between the configurations with one and two stages without affecting the accuracy of the metered flow rate.
• a fuel supply circuit of an aircraft engine comprising a low pressure pumping system connected to a high pressure pumping system by a low pressure supply line, the pumping system.
• high pressure having first and second volumetric pumps driven simultaneously by the engine to output high pressure fuel to combustion chamber injectors and actuators of variable geometry of the engine,
• a hydraulic actuator having a supply port connected to the outlet of the first pump, a high pressure operating port connected to the outlet of the second pump, and a low pressure operating port connected to the supply line to low pressure by a fuel recirculation line, the supply port being connectable to the high pressure operating port or the low pressure operating port depending on the position of a spool of the spool. actuator;
• a fuel dispenser comprising a slide-in slide in a cylinder and carrying three spans which share the internal volume of the cylinder into two control chambers at the ends of the cylinder; cylinder and connected to a servovalve and two passage sections located between the seats, one of the passage sections being connected to the outlet of the high-pressure pumping system and opening towards the combustion chamber injectors, the other passage section being connected to the output of the high-pressure pumping system and opening into a high-pressure control chamber of the hydraulic actuator, the actuator further having a low-pressure pilot chamber which is connected to the fuel recirculation line, the pressures applied in the control chambers of the actuator acting in opposition to one another to control the movement of the actuator slide.
• Controlling the pressure in the control chambers of the hydraulic actuator enables switching of the high pressure pumping system between the single pump configuration and the two pump configuration.
• the position of the hydraulic actuator spool determines the one or two pump configuration of the high pressure pump system.
• these switches do not require any modification of the control valve.
• the metering accuracy of the fuel is only slightly affected during these switching operations.
• the stability of the injected flow is improved.
• the configuration of the two-pump high-pressure pumping system is controlled when the rotational speed of the turbojet engine is low (which corresponds to the re-ignition and autorotation operating points or "windmilling") and when the flow rate injected fuel is high (corresponding to take-off and climb operating points).
• the single pump configuration it is controlled for the other operating points of the engine, especially for the operating points between idle and cruising.
• the high pressure control chamber of the hydraulic actuator communicates with an intermediate control chamber connected to the fuel supply circuit upstream of the low pressure pumping system and in which a spring is positioned.
• the fuel supply circuit further comprises a fuel recirculation line connecting the output of the high pressure pumping system to the low supply line. pressure, and a control valve positioned on the fuel recirculation line.
• a non-return valve is positioned between the high pressure use port of the hydraulic action and the outlet of the second pump.
• the invention also relates to an aircraft engine comprising a fuel supply circuit as defined above. Brief description of the drawing
• a fuel supply circuit according to the invention is described below in the context of an application to a gas turbine engine.
• the scope of the invention extends to gas turbine engines of other aircraft, including helicopters and aircraft engines other than gas turbine.
• the fuel supply circuit 10 comprises a low pressure pumping system 12, a fuel / oil heat exchanger 14, a fuel main filter 16 and a high pressure pumping system 18.
• the low pressure pumping system 12 is connected upstream to the fuel tanks of the aircraft (not shown) and downstream to the high pressure pumping system 18 via a low pressure supply line 20.
• the fuel supply circuit 10 is divided into several distinct fuel lines, namely: a fuel line 22 for fueling combustion chamber injectors 24 ; another fuel line 26 for supplying actuators 28 with variable geometries of the engine; and a fuel recirculation line 30 provided with a control valve 32 for returning the unused fuel flow to the low pressure supply line 20 upstream of the heat exchanger 14.
• the fuel line 22 for the fuel supply of the combustion chamber injectors 24 also comprises a fuel metering device 100 (detailed later) controlled by a servovalve 34, and a pressurization valve 36 also controlled by a servovalve 38 for the cutoff functions.
• the high-pressure pumping system 18 of this circuit is of the two-stage type, that is to say that it consists of two positive-displacement gear pumps 18a, 18b which are driven simultaneously by the engine according to engine displacement laws. different. More specifically, the first pump 18a has a larger displacement than the second pump 18b, that is to say that it allows in operation to inject a larger fuel flow than that injected into operation by the second pump. In other words, the first pump 18a of the high pressure pumping system has a higher pumping capacity than the second pump 18b.
• the low pressure pumping system 12 as well as the two pumps 18a, 18b of the high pressure pumping system 18 are simultaneously driven by the high pressure shaft of the engine via an AGB gearbox (or accessory relay box).
• AGB gearbox or accessory relay box
• the fuel supply circuit 10 also comprises a hydraulic actuator 200 which is interposed between the respective outlets 40a, 40b of the two pumps 18a, 18b of the high pressure pumping system and which can take two different positions; a first position in which the outlets 40a, 40b of the two pumps communicate with each other to combine their flow rates with a view to delivering fuel under high pressure to the combustion chamber injectors 24 and the variable geometry actuators 28, and a second position in which the outlet 40a of the first pump 18a communicates with a fuel recirculation line 42 for discharging the entire output flow of the first pump to the low pressure supply line 20.
• the hydraulic actuator 200 comprises a slide 202 movable in linear translation in a cylinder.
• the actuator 200 also includes a supply port OA connected to the outlet 40a of the first pump 18a, a high pressure utilization port LU connected to the outlet 40b of the second pump 18b, and a low pressure port LJ2 connected to the low-pressure supply line 20 through the fuel recirculation line 42, the supply port OA being connectable to the high-pressure use port U1 or the low-use port pressure U2 depending on the position of the drawer 202 of the actuator.
• the position of the slide 202 of the hydraulic actuator defines the two positions previously described: in the first position, the supply port OA is connected to the high pressure use port U1 so that the outputs 40a, 40b of the two pumps communicate with each other, and the low pressure use port U2 is masked; in the second position, the supply port OA communicates with the low pressure utilization port U2 to allow recirculation of the fuel to the low pressure supply line 20 via the recirculation line 42, and the orifice high pressure user is hidden.
• the hydraulic actuator further comprises three control chambers, namely: a high pressure pilot chamber PI connected to the fuel metering device 100, a low pressure piloting chamber P2 connected to the fuel recirculation line 42 via a bypass line 44 , and an intermediate control chamber P3 connected to the fuel supply circuit upstream of the low pressure pumping system 12 via a fuel line 46. Furthermore, the control chambers PI and P3 communicate with each other by means of a channel 204 made in the drawer 202 of the actuator. In addition, a spring 206 is housed in the intermediate control chamber P3.
• the fuel dispenser 100 which is connected to the high pressure pilot chamber 1 of the actuator makes it possible to vary the pressure in this chamber.
• the fuel dispenser 100 comprises a slide 102 that can slide in a cylinder and carrying three spans 104, 106 and 108. The spans share the internal volume of the cylinder in two control chambers 110, 112 located at the ends of the cylinder and passage sections 114, 116 located between the staves.
• the control chambers 110, 112 are connected to the servovalve 34 by control lines.
• the passage section 114 delimited between the bearing surfaces 104 and 106 is connected to the outlet of the high-pressure pumping system 18 and opens through a use orifice 118 to the combustion chamber injectors 24.
• the degree of closure of the use port 118 by span 104 determines the metered fuel flow.
• the other passage section 116 is also connected to the output of the high-pressure pumping system 18 and opens through a use port 120 in the high-pressure control chamber PI of the hydraulic actuator 200.
• the servovalve 34 acts on the pressures in the control chambers 110, 112 of the fuel metering device 100 so that the metering use port 120 be completely hidden.
• the pressure in the high pressure pilot chamber PI of the actuator 200 is therefore close to the pressure PCA of the line of the fuel supply circuit upstream of the low pressure pumping system 12 (because it is connected via the chamber intermediate de3 pilot and fuel line 46).
• the slide 202 of the actuator 200 moves into the first position where the outputs 40a, 40b of the two pumps 18a, 18b of the high pressure pumping system communicate with each other to combine their flow rates.
• the servovalve 34 acts on the pressures in the control chambers 110, 112 of the fuel dispenser 100 so that the orifice of use 120 of the dispenser is completely hidden.
• the pressure in the high pressure pilot chamber PI of the actuator 200 is therefore always close to the pressure PCA.
• the outlet pressure of the low pressure pumping system 12 increases (with respect to the operating points at low speed) so that the pressure P B P which prevails inside the low pressure control chamber 2 comes from counteract the force exerted by the spring 206 positioned in the intermediate control chamber ⁇ 3.
• the slide 202 of the actuator 200 moves into the second position where the output flow of the first pump 18a is discharged to the low pressure supply line 20.
• the servovalve 34 acts on the pressures in the control chambers 110, 112 of the fuel metering device 100 so that the port of use 120 of the dispenser is discovered so that the pressure in the high pressure pilot chamber PI of the actuator corresponds to the high pressure pressure HPP output of the second pump 18b.
• This high pressure P H is greater than the pressure P B P prevailing in the low pressure control chamber P2 of the actuator, the latter still being in communication with the low pressure supply line 20.
• the slide 202 of the actuator 200 moves into the first position where the outlets 40a, 40b of the two pumps 18a, 18b of the high pressure pumping system communicate with each other to combine their flow rates.
• a nonreturn valve 50 is positioned on the fuel line connecting the high-pressure use port U1 of the hydraulic actuator 200 to the outlet. 40b of the second pump 18b. This non-return valve makes it possible to avoid the flow calls by the actuator during commutations.
• the fuel recirculation line 42 may lead to the low-pressure supply line 20, either upstream of the heat exchanger 14, or between the heat exchanger 14 and the main fuel filter 16, or downstream of the main fuel filter (upstream of sharing between the inputs of the two pumps 18a, 18b of the high pressure pumping system or upstream of the inlet of the first pump 18a as shown in the single figure).
• the hydraulic actuator may not include an intermediate chamber connected to the fuel circuit upstream of the low pressure pumping system as described above.
• the spring is then housed in the high pressure pilot chamber Pl.
• the positive displacement pumps of the high pressure pumping system are not necessarily geared but could be of the vane type.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Fuel-Injection Apparatus (AREA)

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• 2009
  • 2009-10-06 FR FR0956952A patent/FR2950864B1/fr not_active Expired - Fee Related
• 2010
  • 2010-09-30 US US13/500,756 patent/US9222418B2/en active Active
  • 2010-09-30 EP EP10776770.9A patent/EP2486261B1/fr active Active
  • 2010-09-30 CN CN201080045389.1A patent/CN102575586B/zh active Active
  • 2010-09-30 WO PCT/FR2010/052064 patent/WO2011042642A1/fr not_active Ceased
  • 2010-09-30 CA CA2776314A patent/CA2776314C/fr active Active
  • 2010-09-30 BR BR112012008011-3A patent/BR112012008011B1/pt active IP Right Grant
  • 2010-09-30 JP JP2012532647A patent/JP5666604B2/ja active Active
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