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
  • F02C9/26—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
  • 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
  • F02C9/46—Emergency fuel control
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2200/00—Mathematical features
  • F05D2200/20—Special functions
  • F05D2200/22—Power
  • F05D2200/221—Square power
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T50/00—Aeronautics or air transport
  • Y02T50/60—Efficient propulsion technologies, e.g. for aircraft

Definitions

• the present disclosure relates to a metering device of a fuel supply circuit of an engine.
• the fuel system of the turbomachine typically fulfills several functions: it allows the fuel to be sucked from the tank, to put it under pressure, to perform dosing according to the instruction of the computer, and finally to distribute the fuel to the injectors .
• the fuel system may comprise a metering device equipped with a controllable valve. Different dosing laws can be used to control this valve.
• the present disclosure relates to a metering device of a fuel supply circuit of an engine comprising a metering valve and a pressure regulating device maintaining a constant pressure difference between the downstream and the upstream of the valve.
• metering valve wherein the metering valve comprises a seat, provided with an inlet and an outlet, a shutter, disposed within the seat, and an actuator, controlling the position of the shutter, and wherein the shutter defines a passageway between the inlet port and the outlet port whose minimum section is variable depending on the position of the shutter along a stroke extending between a lower stopper and an upper stop and passing through a threshold position.
• the shutter is configured so that, on the one hand, the minimum cross section of said passage, and thus the flow of fuel passing through the valve, increases linearly as a function of the coordinate of the position of the shutter between the lower stopper. and the threshold position and that, on the other hand, the minimum section of said passage, and therefore the fuel flow, increases quadratically, or more rapidly, depending on the coordinate of the position of the shutter between the threshold position and the upper stop.
• the pressure difference between the downstream and the upstream of the metering valve being kept constant by the pressure regulating device, the speed of the fuel circulating in the metering device is constant. Therefore, the fuel flow through the metering valve is directly proportional to the minimum cross section of the valve passage. Thus, at given flow quality, the fuel flow is completely determined by the value of the pressure difference between the downstream and the upstream of the metering valve. kept constant, and the position of the shutter within the seat of the valve.
• This position of the shutter is marked by a coordinate that can vary between a minimum coordinate, corresponding to the lower stop position of the shutter, and a maximum coordinate, corresponding to the upper stop position of the shutter, these positions of the shutter.
• lower and upper stop defining the limits of the maximum travel of the shutter can be indifferently defined by a number of steps, an angle or a distance traveled from the lower stop, or any other reference position, or by a distance ratio with respect to the maximum travel of the shutter, or any other suitable unit.
• the fuel flow increases linearly: in this range of positions, the fuel flow is thus an affine function of the coordinate of the fuel. the position of the shutter. In other words, for each step of the shutter, the fuel flow increases or decreases by a given amount.
• the fuel flow increases quadratically or faster: in this range of positions, the fuel flow is thus a function of the second degree of the coordinate of the position of the shutter, or of higher degree, or exponential, or of any type whose growth rate is greater than that of a function of the second degree.
• this metering device it is possible to benefit from a high resolution, that is to say a fine adjustment of the flow rate for each step of the shutter, in a main range of positions of the shutter while making possible flow peaks, and therefore power peaks for the engine, in a second range of shutter positions whose extent can be reduced.
• a high resolution that is to say a fine adjustment of the flow rate for each step of the shutter
• power peaks for the engine in a second range of shutter positions whose extent can be reduced.
• there is a strong robustness of the dosage in the main field since a small error in positioning the shutter, following a failure of the actuator or a resolver, for example, only slightly affects the flow obtained compared to the setpoint, the larger dosing errors that may occur in the second domain being less critical given the high flow rates sought, such occasions requiring peak flow is otherwise infrequent.
• such a metering device lends itself well to increases in nominal fuel flow rates after its design: indeed, such a device can reach in its second range high rates compatible with the increase in nominal rates, while maintaining its robustness in its main domain. It also easily lends itself to pressure differential reductions between the downstream and the upstream of the metering valve, carried out with the aim of increasing overall flow through the valve, because of the ease of recalibration afforded by the linear character of its main domain.
• stop means a terminal of the race provided for the shutter: such an abutment position may be embodied by an effective mechanical stopper blocking the shutter beyond a certain point.
• the metering device may be devoid of such mechanical stops, the computer then prohibiting the displacement of the shutter beyond these abutment positions as they were programmed.
• the metering device is configured such that the value of the minimum section of the metering valve passage is continuous near the threshold position of the shutter.
• the minimum section of said passage quadratically increases depending on the coordinate of the position of the shutter between the threshold position and the upper stop.
• the minimum section of said passage increases exponentially as a function of the coordinate of the position of the shutter between the threshold position and the upper stop.
• the threshold position corresponds to the position of the shutter in which the flow of fuel passing through the valve is equal to a nominal flow rate of the engine.
• the metering device is made to work essentially in the range of positions between the lower stop is the threshold position, that is to say in the linear range where the resolution and robustness of the metering device is the most important. important.
• the shutter can exceed the threshold position to quickly reach the requested flow rate.
• the lower stop corresponds to the position of the shutter in which the fuel flow is zero. In this way, the metering device can completely interrupt the flow of fuel.
• said engine is an aircraft engine and said nominal engine operating rate is the nominal cruising flow or the nominal takeoff rate.
• the upper stop corresponds to the position of the shutter in which the fuel flow is equal to the maximum emergency flow of the engine.
• the metering device is capable of providing the engine with the maximum flow rate enabling it to respond to emergency situations, for example the loss of an engine on a device equipped with several engines.
• the threshold position is at a coordinate of between 50% and 90% of the shutter stroke from the lower stop to the upper stop, preferably between 60% and 80% of this run.
• the shutter is a plug rotated around its central axis by the actuator and said plug has a shutter ring configured to close a variable section of the inlet orifice, the axial width of said shutter ring being constant between a lower abutment azimuth and a threshold azimuth and decreasing linearly between said threshold azimuth and an upper abutment azimuth.
• the shutter is a cam rotated about its central axis by the actuator and said cam has a variable radial thickness providing a variable radial clearance between the inlet orifice and the cam, said thickness radial decreasing linearly between a lower abutment azimuth and an azimuth threshold and quadratically between said threshold azimuth and an upper abutment azimuth.
• the angular stroke of the shutter extends over an amplitude of 70 to 150 °, preferably about 85 °.
• the shutter is a pin driven axially along its central axis by the actuator and said needle is movable within a restriction passage with which it achieves a variable radial play.
• the actuator is a stepper motor. Such a stepper motor allows accuracy and therefore a significant resolution.
• this stepper motor is devoid of reducer. This allows a reduction in mass and cost while improving the reliability of the device.
• the pressure regulating device is a differential valve.
• the present disclosure also relates to a turbomachine comprising a fuel supply circuit equipped with a metering device according to any one of the preceding embodiments.
• the present disclosure also relates to a helicopter comprising a turbomachine according to any one of the preceding embodiments.
• FIG 1 is an overall diagram of a fuel supply circuit of a turbomachine comprising the metering device according to the invention.
• FIG 2A is an axial sectional view of a first embodiment of the metering valve.
• FIG 2B is a perspective view of the shutter of the valve of FIG 2A.
• FIG. 2C is a developed and schematic view of the obturator shutter ring of FIG. 2B.
• FIG 2D is a top view of the obturator shutter ring of FIG 2B.
• FIG 3 and a graph showing the evolution of the fuel flow as a function of the coordinate of the position of the shutter.
• FIG 4A is an axial sectional view of a second embodiment of the metering valve.
• FIG 4B is a section on plane B-B of FIG 4A.
• FIG 5 is an axial sectional view of a third embodiment of the metering valve.
• FIG 1 schematically shows a fuel supply circuit 1 of a helicopter turbomachine.
• a fuel supply circuit 1 comprises a low-pressure pump 11, a filtration, heating and air purging circuit 12, a high-pressure pump 13, a metering device 14, a stopping system 15 , a distribution system 16 and injectors 17, the fuel passing through each of these elements from the reservoir 10 to the combustion chamber 18 of the turbomachine.
• the fuel circulates within the metering device 14 through a main line 20p on which a metering valve 21 is piloted by an actuator 22.
• this actuator 22 is a stepper motor without a gearbox and controlled by the computer of the turbomachine.
• the metering device 14 further comprises a feedback line 20r connected on either side of the valve 21 and on which a differential valve 23 is interposed configured to regulate the pressure difference ⁇ prevailing between the downstream and the upstream of the valve 21.
• the metering device 14 comprises an additional level check valve 24 downstream of the metering valve 21.
• the pressure difference ⁇ extends kept constant and the differences in attitudes being negligible, the flow of fuel passing through the metering valve 21 is directly regulated by the passage section offered by the valve 21.
• FIGS. 2A to 2D illustrate a first exemplary embodiment of such a valve 21 whose passage section is variable.
• This valve 21 comprises a seat 31 provided with an inlet 31e and an outlet 31s in which is introduced a plug 32 connected to its actuator 22 by a shaft 33 of axis A.
• the plug 32 is supported by ball bearings 34 which allow it to rotate freely within the seat 31 when it is controlled by the actuator 22.
• devices for compensating for axial and angular play can be provided to eliminate any axial play. or angular may affect the position of the plug 32.
• This plug 32 of substantially cylindrical shape of axis A, comprises an annular ring 41 which, when the plug 32 is inserted into the seat 31, is positioned in front of the inlet port 31e.
• This annular ring 41 has a variable axial width L so as to close a more or less large section of the inlet orifice 31e as a function of the position of the plug 32 relative to the seat 31.
• the axial width L of the sealing ring 41 is sufficient to completely close the inlet 31e of the valve 21.
• the axial width L is constant but smaller than upstream of the lower abutment point 42 so as to partially open the inlet port 31e of the valve 21.
• the passage area released at the inlet 31e increases linearly.
• the axial width L then decreases linearly, that is to say, proportionally to the distance traveled from the threshold point 43, to a higher stop point 44 of azimuth a4, so that the passage area liberated at the inlet orifice 31e quadratically increases between the threshold point 43 and the upper stop point 44.
• the axial width L of the sealing ring 41 behind the lower abutment point 42 could be chosen to ensure a minimum non-zero flow rate.
• the axial width L of the obturator ring 41 between the lower stop point 42 and this threshold point 43 is chosen so that the passage surface at this threshold point 43 corresponds to a nominal flow DN of the turbomachine.
• this nominal flow DN is that corresponding to the maximum takeoff power PMD at ground level; however, it may also correspond to the maximum ground level PMC cruising power.
• the threshold position of the plug 32 is located at about 66% of its stroke from the lower stop to the upper stop, or at an angular coordinate b3 of about 55 °.
• the end of the inlet orifice 31e of the seat 31 is approximately opposite the upper stop point 44 of the obturator ring 41: the axial width L of the sealing ring 41 at this upper stop point 44 is chosen so that the passage surface at this upper stop point 44 corresponds to a maximum emergency flow rate DU of the turbomachine.
• this emergency flow DU corresponds to the regulatory flow OEI ("One Engine Inoperative").
• the maximum stroke of the plug 32 from the lower stop to the upper stop extends over 85 °. However, it could also extend beyond 110 ° to 150 ° for example.
• the configuration of the obturator ring 41 makes it possible to obtain a linear distribution law between the lower stop position, of angular coordinate b2, up to the threshold position, of angular coordinate b3, and a quadratic metering law from the threshold position to the upper stop position, angular coordinate b4. Therefore, this law being programmed in the computer of the turbomachine, the latter is able to control the plug 32 with the stepper motor 22 in order to bring it to the position corresponding to the reference flow that we provided him.
• FIGS. 4A and 4B illustrate a second exemplary embodiment of a metering valve 121 whose section of passage is variable.
• This valve 121 comprises a seat 131, provided with an inlet 131e and an outlet 131s, in which is introduced a cam 132 connected to its actuator 22 by a shaft 133 of axis A.
• the cam 132 is supported by ball bearings 134 which allow it to rotate freely within the seat 131 when it is controlled by the actuator 22.
• axial and angular play compensating devices can be provided to eliminate possible games axial or angular may affect the position of the cam 132.
• the cam 132 When the cam 132 is inserted into the seat 131, it is positioned near the inlet 131e. It has a radial thickness e variable so as to leave a radial clearance j more or less important in front of the inlet 131e according to its position relative to the seat 131.
• the radial thickness e of the cam 132 is sufficient to completely close the inlet 131e of the valve 121. Then progressing along the cam 132 in in the clockwise direction, this radial thickness e decreases linearly, that is to say, proportionally to the distance traveled, to a threshold point 143 of azimuth a3.
• the radial thickness e then decreases quadratically, i.e., proportionally to the square of the distance traveled from the threshold point. 143, to an upper stop point 144 of azimuth a4.
• FIG 5 illustrates a third embodiment of a metering valve 221 whose passage section is variable.
• This valve 221 comprises a seat 231, provided with an inlet 231e, an outlet 231s, and a restriction passage 231r.
• a needle 232 is inserted into the seat 231 so that its tip 241 engages in the restriction passage 231r.
• the needle 232 is integral with a rod 233 provided with a rack 234 on which meshes with a pinion 235 of the actuator 22, the actuator 22 thus axially driving the needle 232 along its axis A.
• the tip 241 of the needle has a radial thickness e variable so as to achieve a greater or lesser radial clearance with the walls of the restriction passage 231r depending on the position of the needle 232 relative to the seat 231.
• the radial thickness e of the tip 241 is sufficient to completely close the restriction passage 231r.
• this radial thickness e decreases so that the section of the restriction passage increases linearly, that is to say, proportionally to the distance traveled by the needle, to a threshold point .
• the radial thickness e then decreases so that the section of the restriction passage increases quadratically, i.e. proportionally to the square of the distance traveled by the needle from the threshold point to an upper stop point.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Fuel-Injection Apparatus (AREA)
• Measuring Volume Flow (AREA)
• Aviation & Aerospace Engineering (AREA)
• Cooling, Air Intake And Gas Exhaust, And Fuel Tank Arrangements In Propulsion Units (AREA)

Applications Claiming Priority (2)

Publications (1)

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• 2013
  • 2013-03-12 FR FR1352169A patent/FR3003302B1/fr not_active Expired - Fee Related
• 2014
  • 2014-03-07 EP EP14715344.9A patent/EP2971703A1/fr not_active Withdrawn
  • 2014-03-07 RU RU2015143175A patent/RU2015143175A/ru not_active Application Discontinuation
  • 2014-03-07 WO PCT/FR2014/050521 patent/WO2014140460A1/fr active Application Filing
  • 2014-03-07 US US14/773,569 patent/US20160017817A1/en not_active Abandoned
  • 2014-03-07 KR KR1020157028304A patent/KR20160019405A/ko not_active Application Discontinuation
  • 2014-03-07 JP JP2015562277A patent/JP2016516150A/ja active Pending
  • 2014-03-07 CA CA2903249A patent/CA2903249A1/fr not_active Abandoned
  • 2014-03-07 CN CN201480012982.4A patent/CN105026734B/zh not_active Expired - Fee Related

Non-Patent Citations (1)

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