Controlling method and system for compressed air supply to a pneumatic network, in particular in an aircraft

Abstract

A system for supplying compressed air to a pneumatic network includes a load compressor, an air supply and a power shaft driving the load compressor. The system also includes in an air outlet of such load compressor, a connecting channel connected, on the one side, with a channel connected with the pneumatic network and, on the other side, with an air discharge conduct towards an exhaust nozzle. Air flow rate bleed valves are controlled by a processing unit via servo-loops as a function of the pressure sensors and the speed sensor.

Claims

1. A method to control a compressed air supply to a pneumatic network, wherein the compressed air supply is provided by a load compressor, and in a compressed air outlet of the load compressor, a connecting channel is connected, on one side, with a channel connected with the pneumatic network and, on another side, with an air discharge conduit connected with a gas exhaust system, the method comprising: controlling the compressed air supply as a function of instantaneous needs of the pneumatic network by discharging all compressed air not being consumed by the pneumatic network towards the gas exhaust system, via the air discharge conduit, depending on an air pressure supplied to the pneumatic network, operating the load compressor, at a given flight point, at a constant operation point, independent of the instantaneous needs of the pneumatic network, controlling a valve that regulates air access into the load compressor in opening and closing positions according to an open or closed position of a valve at an inlet of the pneumatic network, and wherein controlling the compressed air supply as a function of the instantaneous needs of the pneumatic network further comprises controlling air flow rate bleed valves, using a data processor, as a function of measurements of the air pressure supplied to the pneumatic network made by a pressure sensor arranged on the channel connected with the pneumatic network, one or more of the air flow rate bleed valves being arranged at an inlet to the load compressor and comprising the valve that regulates air access into the load compressor, one or more of the air flow rate bleed valves being arranged on the channel connected with the pneumatic network, and one or more of the air flow rate bleed valves being arranged on the air discharge conduit.

2. The method according to claim 1, wherein controlling the compressed air supply as a function of the instantaneous needs of the pneumatic network further comprises discharging all compressed air not being consumed by the pneumatic network towards the gas exhaust system when the air pressure supplied to the pneumatic network is at a given set point pressure.

3. The method according to claim 1, wherein the one or more air flow rate bleed valves arranged on the air discharge conduit is at least one of a proportional controlling valve positioned based on a predetermined range around a set point pressure, an anti-surge valve, and a safety valve calibrated at the set point pressure.

4. The method according to claim 1, wherein the one or more air flow rate bleed valves arranged at the inlet to the load compressor and the one or more air flow rate bleed valves arranged on the channel connected with the pneumatic network are valves settable at either of two extreme open and closed positions.

5. The method according to claim 1, wherein the one or more air flow rate bleed valves arranged at the inlet to the load compressor is one or more inlet guide vanes or inlet guide valves.

6. The method according to claim 1, wherein a power shaft drives the load compressor in rotation, and the power shaft is a mechanical power shaft of one of an APU unit gas generator, a terrestrial motive unit, a machine tool, a piston engine, or an electrical engine.

7. The method according to claim 6, further comprising controlling a speed of the mechanical power shaft of the APU unit gas generator by a measuring device for a fuel flow rate being injected into a combustion chamber of the APU unit gas generator, the fuel flow rate being adjusted so that the speed of said mechanical power shaft measured by a speed sensor corresponds to a constant set point value.

8. The method according to claim 1, wherein the controlling the valve that regulates air access into the load compressor includes controlling the valve that regulates air access into the load compressor in only two positions, which are the open and closed positions, according to the open or closed position of the valve at the inlet of the pneumatic network.

Description

BRIEF DESCRIPTION OF THE UNIQUE FIGURE

(1) Other aspects, characteristics and advantages of the invention will appear in the following non-limiting description related to a particular exemplary embodiment, referring to the accompanying unique FIGURE.

(2) This FIGURE represents a non-limiting illustrative example of a base architecture for a compressed air supply system to an aircraft pneumatic network and being controlled according to the invention from a load compressor being driven by a power shaft of an APU unit.

DETAILED DESCRIPTION OF ONE EMBODIMENT

(3) Referring to the unique FIGURE, the exemplary base architecture for a compressed air supply system 1 to a pneumatic network of an aircraft comprises a load compressor 10 being driven by the power shaft 11 of an APU unit 3 of an aircraft. An APU unit is applied, when the aircraft is on the ground or sometimes in flight, for a non-propulsive energy supply. In particular on a descent phase, extra pneumatic energy can be necessary so as to provide an efficient de-icing of the airplane or to release the main engines from non-propulsive functions.

(4) The APU unit 3 includes a gas generator 30—coupling a main compressor 31, a combustion chamber 32 and a power turbine 33—and a gas ejection nozzle 34 in post-combustion.

(5) An air supply 4 provides air to the main compressor 31 and the load compressor 10 via IGVs 12. To do so, the supply 4 is respectively divided into two conduits 4a and 4b through a T-shaped connection 40. The compressor 31 supplies the injectors 32i of the combustion chamber 32 with compressed air Ac pre-mixed with the fuel. The combustion of such mix in the chamber 32 supplies the turbine 33 with high energy gas 6e, thereby driving the power shaft 11 into rotation.

(6) The shaft 11 drives in turn the main compressor 31, the load compressor 10 and a gearbox casing 5. The gearbox casing 5 connects the shaft 11 through gear trains with other energy consuming equipment or materials: alternators, hydraulic pumps or auxiliary engines. As far as it is concerned, the load compressor 10 supplies with compressed air the pneumatic network 2 through a connecting channel 6a.

(7) According to the invention, the system 1 comprises air supply controlling equipment or materials in connection with the base architecture. Thus, on the compressed air outlet of the load compressor 10, the channel 6a is divided to be connected on the one side to the pneumatic network 2 through a connecting channel 6b and, on the other side, to an air discharge conduit 6c towards the gas exhausting nozzle 34. The connections between channels and conduit are made via a T-shaped joint 50.

(8) More particularly, the access to the pneumatic network 2 is controlled by a valve 20 being settable at two extreme opening/closing condition positions when the network 2 requires air. The opening condition of the valve 20 also adjusts the air arrival in the conduit 4a through a command transfer of the opening/closing condition of an IGV 12.

(9) The air discharge towards the nozzle 34 is adjusted in turn by a controlling valve 60 of a variable opening as a function of the air surplus to be discharged.

(10) The controlling valve 60 is here a proportional opening valve adjusted based on a differential provided by a servo-loop B1. The servo-loop B1 comprises a pressure sensor 61 arranged on the connection channel 6b with the network and a comparator 62 providing the pressure differential ΔP between a set point pressure value P0 and the current pressure value Pc measured by the sensor 61. From the differential ΔP, a position command of the controlling valve 60 is made by a transfer function of a data processing unit 6. In the illustrated example, such unit is the digital control unit or FADEC (for Full Authority Digital Electronic Controller) of the APU unit.

(11) Furthermore, the data processing unit 6 also controls the transfer function of the position command of the IGVs for air arrival into the load compressor 10. In particular, the IGVs are controlled in a position so that the complete closing thereof, as soon as no air surplus is required, allows the creation of a penalizing resistive torque.

(12) Moreover, the data processing unit 6 controls the rotation of the mechanical power shaft 11 of the APU unit 3 by controlling a measuring device 13 for fuel 16. Fuel 16 is pre-mixed with compressed air before being injected into the combustion chamber 32 of the APU unit 3 via the injectors 32i. A servo-loop is implemented by a loop B2 comprising a speed sensor 14 arranged on the power shaft 11 and a comparator 15. The comparator 15 provides the differential ΔV between the current speed Vc, being measured by the speed sensor 14, and a set point speed value V0. From the differential ΔV, the data processing unit 6 provides a measuring command for the measuring device 13 via an appropriate transfer function.

(13) The invention is not limited to the examples described and represented herein.

(14) It is for example possible to use other bleed valves than the controlling valve 60, in particular the anti-surge valve or a safety valve calibrated as a function of the set point pressure of the loop B1.

(15) Furthermore, the power shaft can be driven by another mechanical energy generator than an APU unit, for example, in other fields than aeronautics, a turbine or a terrestrial motive unit for a machine tool, an engine piston or an electrical engine.

(16) Moreover the IGVs can be substituted by an adapted disengagement of the air supply.