EP1688625A1 - Control system for a plurality of relief valves of a turbomachine - Google Patents

Abstract

The case has activation outputs (19) corresponding to number of discharge valves (9) and a control input (21) receiving a control signal (23) from an electronic control unit (17). The signal is supplied to a control winding (27) of a distributor unit (29) to provoke a movement of a distribution piston (41) permitting to connect the determined number of the outputs to a pressure supply (37) and other outputs to pressure supply (39). An independent claim is also included for a full authority digital engine control (FADEC) comprising a control system with a pneumatic case.

Description

Field of the invention

The present invention relates to a control system of the discharge valves of a turbomachine and more particularly relates to a pneumatic box for activating a plurality of discharge valves.

Background of the invention

In general, a turbomachine comprises a low pressure upstream compressor BP and a downstream compressor HP high pressure. The two compressors are axial and rotate at different speeds often requiring air sampling at their interface. At idle, to protect the upstream compressor from pumping caused by the mismatch of the two compressor regimes, discharge valves are opened to eject the excess air flow generated by the upstream which can not be absorbed by downstream.

The activation or deactivation of the discharge valves is controlled by a control system integrated in the full authority digital control system (FADEC) of the turbomachine.

FIG. 5 illustrates an example of a control system 115 of discharge valves 109 of a turbomachine according to the prior art.

This system 115 comprises an electronic control unit (ECU) 117 and a pneumatic control unit (SBU) 118 connected via control lines 145 to N relief valves 109. The pneumatic box 118 is equipped with N electro-valves 129a, 129b, 129n, one per relief valve 109.

A deactivated (i.e. open) relief valve 109 corresponds to a rest position of the valve.

To activate (i.e. close) a discharge valve 109, the electronic control unit 117 supplies the associated electro-valve 129a, 129b, 129c which connects the high pressure air 137 to the output of the HP compressor. at the control line 145 of the relief valve 109.

The relief valve 109 has a chamber 143 having a piston 147 acting against a spring 146. Thus, when the chamber 147 of the piston is supplied with high pressure air, the piston 147 moves by compressing the spring 146 and the rod 148 of the piston moves a kinematic chain 149 which causes the closing of an air discharge channel 10 by an internal member 151 of the discharge valve 109.

To reopen the discharge valve 109, the electronic control unit 117 stops supplying the electro-valve 129a, 129b, 129c, which has the effect of connecting the chamber 143 of the piston to an ambient pressure 139. spring 146 then restores the piston 147 in the rest position to reopen the internal member 151 via the drive train 149.

This system nevertheless has many disadvantages. Indeed, the system is quite complex and the controls of the discharge valves 109 frequently request the electronic control unit 117 which is also used to control other important functions of the turbomachine.

Another disadvantage is the fact that the system has no direct means for detecting the position of the relief valve 109 to identify a fault case (valve blocked open or closed). Indeed, in the current systems the failure detection is carried out by observing the behavior of the turbomachine, which reduces the time limit to take corrective action to prevent pumping. On the other hand, the maintenance assistance functions can not locate the fault relief valve 109 in fault.

Object and summary of the invention

The present invention therefore proposes to overcome the aforementioned drawbacks by proposing a pneumatic box for activating a plurality of discharge valves of a turbomachine, the pneumatic box comprising activation outputs corresponding to the number of discharge valves forming said plurality of discharge valves, and a single control input receiving a single control signal from an electronic control unit, the control signal being adapted to act on a control coil of a distributor means whose outputs form said outputs activation.

Thus, the pneumatic box uses a single control signal to control all the discharge valves. This reduces the load on the electronic control unit thus increasing the reliability and safety of the turbomachine.

In addition, it is no longer necessary to have an electro-valve discharge valve thereby reducing the costs, the power consumption of the electronic control unit, and the size of the pneumatic housing.

The distributor means comprises a piston-distributor separating a cavity communicating with the activation outputs, in a first zone at a first supply pressure and a second zone at a second supply pressure, so that the control coil, when it is fed by the control signal, causes a movement of said piston-distributor thus making it possible to connect a determined number of said activation outputs to said first supply pressure, the other outputs being connected to said second supply pressure .

According to a first embodiment of the invention, the piston-distributor is a distributor valve whose linear displacement amplitude is fixed by the control signal.

According to a second embodiment of the invention the piston-distributor is a rotary piston whose angle of rotation is fixed by the control signal.

According to one particular aspect of the invention, the pneumatic box further comprises a feedback device comprising feedback inputs connected one by one to the plurality of discharge valves, the information feedback device transforming feedback of the plurality of discharge valves to a single information signal enabling the electronic control unit to determine an activation or deactivation state of each of the discharge valves.

Thus, the feedback device allows the detection of faults and the location of any faulty discharge valve.

Advantageously, each of the feedback inputs comprises a return piston switching according to the state of activation or deactivation of the valve which is connected to it, between a first resistive element and a second resistive element, the first resistive element having an identical resistance for all the return inputs and the second resistive element having a different resistance for each of the return inputs, the switching of the return piston of each of the feedback inputs for connecting one of the first and second resistive elements of each of the feedback inputs for forming an electrical circuit having an equivalent resistance the value of which indicates the actually activated discharge valves.

The first supply pressure is a high pressure and the second supply pressure is an ambient pressure.

The invention also relates to a control system comprising an electronic control unit, a plurality of discharge valves, and a pneumatic box according to the above characteristics so that each of the plurality of discharge valves comprises a chamber connected via a pneumatic control line at an output of said activation outputs, said chamber comprising a transmission piston whose displacement causes a movement of a kinematic chain causing the activation or deactivation of the corresponding discharge valve.

The discharge valve is in an activated state when the corresponding activation output is connected to the high pressure, and in a deactivated state when the corresponding activation output is connected to the ambient pressure.

Advantageously, the piston chamber of each of the plurality of discharge valves comprises a port at the end of the stroke of the piston for returning the high pressure air to the corresponding feedback input via a line back.

The single control signal sent by the electronic control unit is a current whose intensity is modulated according to the number of discharge valves to be activated.

Advantageously, all the discharge valves are in a deactivated state when the electronic control unit fails.

The electronic control unit is further intended to determine the equivalent resistance of the electrical circuit by measuring the voltage across said electrical circuit.

The invention also relates to a full authority digital control system of a turbomachine comprising a control system according to the above characteristics.

Brief description of the drawings

• la figure 1 est une vue partielle très schématique d'une turbomachine comportant deux compresseurs et un dispositif de décharge ;
• la figure 1A est une coupe schématique au niveau de l'interface entre les deux compresseurs de la figure 1 ;
• la figure 2 illustre très schématiquement un système de commande comportant une unité de commande électronique, une pluralité de vannes de décharge d'une turbomachine, et un boîtier pneumatique d'activation de la pluralité de vannes de décharge conforme à l'invention ;
• la figure 3 est une variante de la figure 2 ;
• la figure 4 illustre très schématiquement un système de commande selon la figure 2 ou 3 comportant en outre un dispositif de retour d'information ; et
• la figure 5 illustre très schématiquement un système de commande selon l'art antérieur.

Other features and advantages of the method and of the device according to the invention will become apparent on reading the description given below, by way of indication but without limitation, with reference to the appended drawings in which:

• FIG. 1 is a very schematic partial view of a turbomachine comprising two compressors and a discharge device;
• Figure 1A is a schematic section at the interface between the two compressors of Figure 1;
• FIG. 2 very schematically illustrates a control system comprising an electronic control unit, a plurality of discharge valves of a turbomachine, and a pneumatic box for activating the plurality of discharge valves according to the invention;
• Figure 3 is a variant of Figure 2;
• FIG. 4 very schematically illustrates a control system according to FIG. 2 or 3 further comprising a feedback device; and
• FIG. 5 very schematically illustrates a control system according to the prior art.

Detailed description of embodiments

FIG. 1 is a very schematic partial view of a turbomachine 1 comprising an upstream low pressure compressor (LP) and a high pressure downstream compressor (HP). FIG. 1A is a diagrammatic section at the interface between the two compressors 3 and 5 of FIG.

In order to improve the conditions of use of the turbomachine, a discharge device 7 comprising discharge valves 9 controlled in all or nothing, are distributed on the periphery of the turbomachine 1.

These discharge valves are mounted on a double skin 11 enveloping the interface section of the two compressors 3, 5 forming a plenum cavity 13 of the air connected to an air evacuation channel 10. The stilling cavity 13 limits the disturbances in the flow vein of the air.

The discharge device 7 can be composed of any number N of the discharge valves 9. Preferably, the number N of the discharge valves 9 is between two and ten.

• Si le pourcentage de débit à prélever < 1/N
  alors, ouvrir 1 vanne
• si 1/N < pourcentage de débit à prélever < 2/N
  alors, ouvrir 2 vannes
• Si i/N < pourcentage de débit à prélever < i+1/N
  alors, ouvrir i vannes
• Si (N-1)/N < pourcentage de débit à prélever
  alors, ouvrir N vannes.

Each discharge valve 9 is sized to take 1 / N of the maximum total flow to be withdrawn. This discharge device therefore uses a control logic of the type:

• If the percentage of flow to be taken <1 / N
  then open 1 valve
• if 1 / N <percentage of flow to be taken <2 / N
  then, open 2 valves
• If i / N <rate percentage to be taken <i + 1 / N
  then, open i valves
• If (N-1) / N <percentage of flow to be withdrawn
  then, open N valves.

According to the invention, FIG. 2 very schematically illustrates a control system comprising an electronic control unit 17, a plurality of discharge valves 9 of a turbomachine 1, and a pneumatic box 18 for activating the plurality of discharge valves 9.

The pneumatic box 18 has activation outputs 19 corresponding to the number N of discharge valves 9 forming the plurality of discharge valves 9, that is to say that each activation output 19 corresponds to a discharge valve 9 .

In addition, the pneumatic box 18 comprises a single control input 21 receiving a control signal 23 from a channel 25 of the electronic control unit 17. This control signal 23 is intended to act on a control coil 27 of the control unit 27. a distributor means 29 whose outputs form said activation outputs 19.

The single control signal 23 sent by the electronic control unit 17 is a direct current whose intensity is modulated according to the number of discharge valves 9 to be activated. Thus, only one channel 25 of the electronic control unit 17 is sufficient to control all the discharge valves 9.

The distributor means 29 comprises a chamber 31 forming a cavity 35 which communicates with the activation outputs 19 as well as with a first supply pressure 37 and a second supply pressure 39.

In addition, the dispensing means 29 includes a distributor piston 41 which can separate the cavity 35 into a first zone 35a at the first supply pressure and a second zone 35b at the second supply pressure.

When the control coil 27 is supplied by the control signal 23, an electromagnetic field is generated inductively inducing a movement of the distributor piston 41 thus making it possible to connect a determined number of the activation outputs 19 to the first supply pressure. 37 to activate the same number of discharge valves 9. On the other hand, the other outputs are connected to the second supply pressure 39.

In general, the first supply pressure 37 is a high pressure and the second supply pressure 39 is an ambient pressure.

Indeed, the air output of the high pressure compressor 5 is taken as a high pressure supply source 37a, while the ambient pressure is a vent 39a.

Each of the plurality of discharge valves 9 comprises a chamber 43 connected via a pneumatic control line 45 to one of the activation outputs 19. Each chamber 43 comprises a transmission piston 47 whose displacement causes a movement of a kinematic chain 49 acting on an internal member 51 causing the closing or opening of the conduit 10 that is to say, the activation or deactivation of the corresponding discharge valve 9.

It will be noted that the discharge valve 9 is in an activated state (closed valve) when the corresponding activation output 19 is connected to the high pressure 37 and is in a deactivated state (open valve) when the output of corresponding activation 19 is connected to the ambient pressure 39.

Indeed, when the chamber 43 of the discharge valve 9 is supplied with high pressure air 37, the transmission piston 47 moves by compressing a spring 46 and the piston rod 48 moves the kinematic chain 49 which triggers the closure of the channel exhaust air 10 by the inner member 51 of the corresponding discharge valve 109.

On the other hand, when the chamber 43 of the discharge valve 9 is supplied with air at ambient pressure 39, the spring 46 then repositions the transmission piston 47 in the rest position to reopen the butterfly valve 51 via the kinematic chain 49.

According to the example of FIG. 2, the distributor-piston 41 is a distributor slide comprising a translation piston 41a connected to a counter-force spring 53. The translational piston 41a moves in a cylindrical distribution chamber 31 having a generator of a length proportional to the number N of valves of discharge 9. The inlet of the high-pressure air 37 is disposed at one end of the distribution chamber 31, while the inlet of the ambient-pressure air 39 is disposed at the other end of this chamber 31 Furthermore, the activation outputs 19 are arranged at regular intervals between these two high pressure 37 and ambient pressure inputs 39.

The amplitude of the linear displacement of the distributor slide 41 is fixed by the control signal 23 and its position is stabilized by the counter-force spring 53.

Thus, a given position of the slide valve 41 corresponds to a given number of closed discharge valves 9. The position of the spool valve 41 is itself determined by the intensity of the current of the control signal 23. Consequently, the current command coming from the electronic control unit 17 makes it possible to close the number of required discharge valves 9 .

According to the example of FIG. 2, the distributor slide 41 has a position allowing the closing of two discharge valves 9.

It will be noted that, in the event of loss or failure of the electronic control unit 17, the counter-force spring 53 brings the dispensing slide 41 to a position corresponding to the opening (deactivated state) of all the discharge valves 9, which prevents any pumping during the deceleration of the compressors.

Advantageously, the electrical part of the distributor means 29 is redundant so that each channel of the electronic control unit 17 can control all the discharge valves 9 independently.

FIG. 3 is a variant of FIG. 2, very schematically illustrating a control system of a plurality of discharge valves 9. The example of FIG. 3 differs from that of FIG. 2 in that the piston distributor is a rotary piston 41b which can rotating inside a distribution chamber 31 having a diameter of a length proportional to the number N of discharge valves 9.

The single control signal 23 acts on the control coil 27 of the rotary piston 41b. The control coil 27 may in known manner be integrated with a stepper motor to act on the angular orientation of the rotary piston 41b.

This rotary piston 41b is for example in the form of butterfly whose angular orientation corresponds to a given number of closed discharge valves 9.

Indeed, the inputs of the high pressure air 37 and at ambient pressure 39 are arranged diametrically opposite. Moreover, the activation outputs 19 may be arranged at regular intervals over a circumferential half of the distribution chamber 31 between the high pressure 37 and ambient pressure 39 inputs.

The rotation angle of the rotary piston 41b is itself determined by the intensity of the current of the control signal 23. Consequently, the current control coming from the electronic control unit 17 makes it possible to close the number of valves of discharge 9 wanted.

The example of FIG. 3 shows a rotary piston 41b having an angular orientation which allows the closure of a single discharge valve 9.

FIG. 4 very schematically illustrates a control system 15 of a plurality of discharge valves 9 comprising a feedback device 53.

In fact, the pneumatic box 18 of FIG. 4 differs from that of FIG. 2 or 3 in that it furthermore comprises an information feedback device 53 comprising connected pneumatic feedback inputs 55. one to one to the plurality of discharge valves 9.

This feedback device 53 makes it possible to indicate an activation (closing) or deactivation (opening) state of each of the discharge valves 9. Therefore, any faulty discharge valve 9 can be immediately located.

Indeed, the feedback device 53 converts the pneumatic feedback of the plurality of discharge valves 9 into a single information signal 57 enabling the electronic control unit 17 to determine an activation state. or deactivating each of the discharge valves 9.

Consequently, it is sufficient to allocate a single channel 26 of the electronic control unit 17 to measure the single information signal 57 sent by the pneumatic box 18.

By way of example, each of the feedback inputs 55 comprises a return piston 59 switching according to the state of activation or deactivation of the discharge valve 9 connected to it, between a first resistive element 61 and a second resistive element 63. The first resistive element 61 has an identical resistor R0 for all the information feedback inputs 55. The second resistive element 63 has a different resistor R1, R2, ... Ri, ... RN for each of the information feedback inputs 55 and also different from that of the first resistive element 61, that is to say R0 ≠ R1 ≠ R2 ≠ ... ≠ Ri ≠ ... ≠ RN.

The switching of the return piston 59 of each of the feedback inputs 55 makes it possible to connect one of the first and second resistive elements 61, 63 of each of the information feedback inputs 55 to one another in series with one another in series. electrical circuit 65 whose equivalent resistance indicates the actual state of activation of the discharge valves 9. It will be noted that the resistive elements of the electrical circuit 65 can also be connected in parallel.

The electronic control unit 17 supplies electricity to the electrical circuit 65 which passes through the N switched resistances (one per valve) and measures, via an interface 67 of the pneumatic box 18, the voltage at the terminals of this electrical circuit 65 in order to determine the resistance equivalent of this circuit 65.

The chamber 43 of the piston of each of the plurality of discharge valves 9 has an orifice 69 at the end of travel of the transmission piston 47 for returning the high pressure air to the corresponding input 55 of feedback information by the intermediate of a return line 71.

Thus, when the pneumatic box 18 sends high pressure air into the control line 45 of the discharge valve 9 to cause it to close, the translation of the transmission piston 47 discovers at the end of the stroke the orifice 69 which returns high pressure air to the feedback device 53 through the dedicated return line 71. At the inlet of this return line 71 on the pneumatic box side 18, the return piston 59 of the inlet 55 is translated under the effect of the pressure and switches the resistance associated with the discharge valve 9 from R0 to R1. (Ri being the resistance of the second resistive element 63 of the input 55 of corresponding feedback). The resistance read by the electronic control unit 17 is then changed indicating the closure of the discharge valve 9. According to this example, the default value of the resistance associated with a discharge valve 9 open is R0.

Note that, the resistors are differentiated by discharge valve 9 to allow the immediate detection (within the response time of the electronic control unit 17) of a blockage of a discharge valve 9 and the location of this faulty valve 9 for subsequent maintenance operations.

Advantageously, the electrical part of the feedback device 53 is redundant to allow each channel of the unit of electronic control 17, an independent reading, of the equivalent resistance of the electrical circuit 63.

Thus, the control system 15 according to the invention makes it possible to control several discharge valves 9 of the all or nothing type by a single electrical signal 23.

Similarly, it makes it possible to measure the position of these discharge valves 9 by a single information signal 57. It thus makes it possible to locate a faulty discharge valve 9 while reducing the detection times of this faulty valve.

In addition, the control system 15 makes it possible to reduce the number of electronic control circuits allocated to the control of discharge valves 9.

The control system 15 also reduces the power consumption of the electronic control unit 17.

Of course, the control system 15 described above is integrated with a full authority digital control system (FADEC) of the turbomachine 1.

Claims (14)

Pneumatic housing (18) for activating a plurality of discharge valves (9) of a turbomachine (1), the pneumatic housing (18) having activation outputs (19) corresponding to the number of discharge valves ( 9) forming said plurality of discharge valves (9), characterized in that it comprises a single control input (21) receiving a single control signal (23) from an electronic control unit (17), the signal control unit (23) being adapted to act on a control coil (27) of a distributor means (29) whose outputs form said activation outputs (19), said distributor means (29) comprising a distributor piston ( 41) which separates a cavity (35) communicating with the activation outputs (19) into a first zone (35a) at a first supply pressure (37) and a second zone (35b) at a second pressure of supply (39), so that the control coil (27), when powered by the control signal 23, causes a movement of said piston-distributor (41) thus making it possible to connect a determined number of said activation outputs (19) to said first supply pressure (37), the other outputs being connected to said second supply pressure (39). Pneumatic case according to claim 1, characterized in that the piston-distributor (41) is a distributor slide whose linear displacement amplitude is fixed by the control signal (23). Pneumatic case according to claim 1, characterized in that the piston-distributor (41) is a rotary piston (41b) whose rotation angle is fixed by the control signal (23). Pneumatic case according to any one of claims 1 to 3, characterized in that it further comprises an information feedback device (53) comprising feedback inputs (55) connected one by one to the plurality of the discharge valve (9), the feedback device (53) transforming the feedback of the plurality of discharge valves (9) into a single information signal (57) enabling the electronic control (17) to determine an activation or deactivation state of each of the discharge valves (9). Pneumatic housing according to claim 4, characterized in that each of the feedback inputs (55) comprises a return piston (59) switching according to the activation or deactivation state of the discharge valve (9) which connected thereto, between a first resistive element (61) and a second resistive element (63), the first resistive element (61) having identical resistance for all the feedback inputs (55) and the second resistive element ( 63) having a different resistance for each of the feedback inputs (55), the switching of the return piston (59) of each of the feedback inputs (55) for connecting one of the first and second resistive elements (61, 63) of each of the feedback inputs (55) for forming an electrical circuit (65) having an equivalent resistance the value of which indicates the actually activated discharge valves (9). Air box according to claim 1, characterized in that the first supply pressure (37) is a high pressure and the second supply pressure (39) is an ambient pressure. A control system (15) comprising an electronic control unit (17), a plurality of discharge valves (9), and a pneumatic housing (18) according to any one of claims 1 to 6, characterized in that each of the plurality of discharge valves (9) comprises a chamber (43) connected via a pneumatic control line (45) to an output of said activation outputs (19), said chamber (43) having a transmission piston (47) whose displacement causes a movement of a kinematic chain (49) causing the activation or deactivation of the corresponding discharge valve (9). System according to claim 7, characterized in that the discharge valve (9) is in an activated state when the corresponding activation output (19) is connected to the high pressure. System according to Claim 7, characterized in that the discharge valve (9) is in a deactivated state when the corresponding activation output (19) is connected to the ambient pressure. System according to any one of claims 7 to 9, characterized in that the chamber (43) of each of the plurality of discharge valves (9) comprises an orifice (69) at the end of travel of the transmission piston (47). for returning the high pressure air to the corresponding feedback input (55) through a return line (71). System according to any one of claims 7 to 10, characterized in that the single control signal (23) sent by the electronic control unit (17) is a current whose intensity is modulated according to the number of valves discharge device (9) to be activated. System according to one of Claims 7 to 11, characterized in that all the discharge valves (9) are in a deactivated state when the electronic control unit (17) fails. System according to any one of claims 7 to 12, characterized in that the electronic control unit (17) is further intended to determine the equivalent resistance of the electric circuit (53) by measuring the voltage across said electrical circuit. Full authority digital control system of a turbomachine (1), characterized in that it comprises a control system (14) according to any one of claims 7 to 13.

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