Device and method for controlling the operation of turboshaft engines for accommodating servo failures of variable-geometry elements

Abstract

Device and method for adapting (1, 5) the operation of a turboshaft engine comprising a variable-geometry element (2), the position of which is dependent on at least one parameter (3), allowing detection of a servo failure of the variable-geometry element and adaptation of the operation of the turboshaft engine by servo-controlling said at least one parameter by setting a setpoint value (Vcons) determined on the basis of the current value (Pcour) of the position of the variable-geometry element so as to impose a particular engine speed.

Description

Description Title of the invention: Device and method for controlling the operation of turboshaft engines to accommodate failures in the control systems of variable geometry elements Technical Field

[0001] The invention relates to the management of control failures of a turbomachine, in particular control failures of the variable geometry elements of a turboengine.

[0002] The field of application of the invention is that of aeronautical turboshaft engines, in particular aircraft turboshaft engines. Previous technique

[0003] A turboshaft engine typically comprises variable geometry elements controlled by actuators whose positions are modified according to pilot instructions or other external conditions. The control of these variable geometry elements is achieved through position control of all or some of them. It is well known to perform control failure detection, that is, to detect an excessive deviation between a target position and an actual position, for example, due to an actuator malfunction.

[0004] In response to these fault detections, the usual procedure is to send an alert message to the pilot who must then slow down the thrust or even stop the faulty turboshaft engine, otherwise the servo failure can for example cause a compressor to pump and generate a significant loss of turboshaft thrust, or even break the compressor blades, which can lead to significant damage.

[0005] Thus, the detection of such failures can lead to the interruption of the flight, particularly during a flight of a single-engine aircraft.

[0006] Control system failures can be permanent, for example, when the variable-pitch element is stuck in a fixed position, but they can also be temporary, for example, when the variable-pitch element's position does not change as quickly as the target position, such as during turboshaft engine transients. Unfortunately, regardless of the type of failure, the pilot will have to slow down and then shut down the turboshaft engine.

[0007] US 2013 / 236290 describes a turbomachine monitoring system comprising a variable geometry component, the system comprising a first sensor to detect a state of the component and a second sensor to detect an operating state of the turbomachine associated with an operation of the component, the system further comprising a controller coupled to the first and second sensors and configured to execute a turbomachine process based on the result of the second sensor, independently of the result provided by the first sensor.

[0008] Therefore, there is a need to enable flight to continue in the event of a control system failure while keeping the turboshaft engine running. Furthermore, it is desirable to be able to guarantee continued engine operability with sufficient thrust. In general, it would be beneficial to improve the management of control system failures in a turboshaft engine.

[0009] The invention aims to meet all or part of these needs. Description of the invention

[0010] To this end, the invention proposes a method for adapting the operation of a turboshaft engine comprising at least one variable geometry element, or variable timing element, whose position depends on at least one parameter, the method comprising the following steps: a) detection of a malfunction of said turboshaft engine based on a deviation between the current value of said position and a target position, b) adaptation of the turboshaft engine speed by controlling said at least one parameter by setting a setpoint value determined from said current value.

[0011] The adaptation method according to the invention has the advantage of allowing the engine to remain in flight while minimizing or even preventing damage to the turboshaft engine. In particular, the method allows the turboshaft engine to be maintained in a functional position by adapting its operation to the position of the variable-pitch element for which the turboshaft engine was initially detected as being in a malfunctioning state.

[0012] The detection of the malfunction may result from an abnormally slow change in the value of the position of said variable timing element to reach the target position, for example during an acceleration or deceleration of power or speed of the turbojet, from a blockage of the value of the position of the variable timing element, or from an uncontrolled change in the value of the position of said variable timing element.

[0013] The method according to the invention advantageously allows adaptation of the operation of the turbomotor regardless of the origin of the malfunction.

[0014] Preferably, the variable-positioning element is kept in position in parallel with the control of said at least one parameter.

[0015] For example, thanks to the invention, it is possible to adapt the engine speed by modulating the fuel injected into the combustion chamber, taking into account the current position value of the variable geometry element detected as being in fault, in order to adapt the engine operating point to said position value detected as being in fault.

[0016] The invention can limit the risk of damage to the turbocharger while allowing a return to normal operation, thus avoiding permanent idling or a complete shutdown of the turbocharger. In particular, in the case of a temporary malfunction, for example, an abnormally slow speed variation, the invention allows the transient operating conditions to be managed by adapting the engine speed to the faulty variable-timing element and, ultimately, to reach the correct position. target and thus return to normal operation of the turboshaft engine. In the event of a permanent malfunction, for example when the position value of the variable-timing element is blocked, the invention can make it possible to maintain the turboshaft engine's thrust and can in particular promote flight stability.

[0017] In general, the invention enables the activation of a control system upon detection of a malfunction indicating that the current position of at least one variable geometry element does not correspond to the expected target position. This system imposes an engine speed adapted to the current position of said variable geometry element. The turbocharger's operation is then defined according to the current position of the at least one variable geometry element for which a fault has been detected. In particular, the current position of the variable geometry element is preferably maintained in a position that may allow it to converge towards the target position, with the setpoint value being adjusted according to the current value.

[0018] In particular embodiments of the invention, the target position of the variable geometry element is recalculated from an effective value for at least one parameter, the control of said parameter enabling the variable geometry element to maintain a position as close as possible to its current position at the time the malfunction is detected. This allows the thrust to be maintained similarly to the engine thrust at the time the malfunction is detected.

[0019] Alternatively, in parallel with the control of said at least one parameter, the target position of the variable geometry element can be defined independently of the actual value of said parameter. In other words, in response to the detection of a malfunction, the operation of the position control of the variable geometry element can be modified. In particular, the target position can be maintained at its initial value, that is, at the value as defined at the time the malfunction was detected, potentially enabling convergence of the engine speed operation towards operation as desired before the malfunction was detected.

[0020] The setpoint value set to control the parameter and adapt the operation of the engine speed can come from the inversion of a setpoint law controlling the control of the position of the variable geometry element, in particular the setpoint law controlling the control of the position of the variable geometry element in normal operation.

[0021] In particular embodiments of the invention, the adaptation method includes a selection of said setpoint value from a lookup table providing for each position of a set of positions of the variable geometry element a predefined setpoint value for said parameter, the lookup table preferably being predefined by means of the inversion of the setpoint law controlling the control of the position of the variable geometry element.

[0022] Alternatively, the setpoint value can be calculated over time based on the current value.

[0023] Detecting a malfunction may involve comparing the deviation to a threshold value. The threshold value is not limited to a fixed value; it can be variable. In particular, the threshold value may vary depending on the value of the target position. The threshold value may also vary depending on the sign of the deviation. Alternatively, the threshold value is the same whether the deviation is positive or negative; in other words, the threshold value can be compared to the absolute value of the deviation. The threshold value preferably depends on the variable geometry element.

[0024] The adaptation process may also include a step of controlling the injection of a fuel flow into the turbocharger according to the setpoint value, the parameter being for example related to a fuel flow or a rotational speed of a drive shaft.

[0025] In preferred embodiments of the invention, the method comprises interrupting the control of said at least one parameter as a function of a stopping criterion, the control of the parameter being interrupted as soon as the stopping criterion is met.

[0026] The stopping criterion can be considered met when it is determined that the variable geometry element has the ability to reach the target position, in other words, as soon as it is determined that the variable geometry element has the ability to be controlled in position according to the normal operation of the turbomachine.

[0027] This interruption allows for a return to normal turbocharger operation, particularly in the event of a temporary failure, such as a seizure that could slow the actuation capabilities of the variable geometry element. Normal operation refers to the turbocharger's operation before the fault is detected, specifically the normal operation before the parameter control is activated.

[0028] Determining the ability of a variable geometry element to reach its target position can be achieved by analyzing data acquired from sensors to identify the cause of the malfunction. This analysis may involve determining a change in environmental conditions and / or the operating state of the variable geometry element or of all or part of a control system that regulates its position. The sensors may include at least one of the following: a temperature sensor, a pressure sensor, or a camera.

[0029] Alternatively or additionally, said determination may include comparing a difference between the current position value and the target value.

[0030] The method may include, in preferred embodiments of the invention, sending information indicating the presence of a malfunction to an operator allowing, for example, subsequent maintenance, or a modification of piloting instructions for an aircraft comprising said turboshaft engine.

[0031] All or part of the steps in the adaptation process can be implemented by computer; preferably all steps in the process are implemented by computer.

[0032] Thus, the invention also relates to a computer program comprising code instructions which, when implemented, allow the execution of the steps of a method for adapting the operation of a turboengine according to the invention, this program being capable of being implemented in a control module, for example already existing in the turboengine or aircraft.

[0033] The computer program may include code instructions which, when executed, allow setting a target value for the parameter, determined from the current value. This target value can be transmitted, for example, to actuators, so as to allow the control of the parameter and ultimately the adaptation of the engine speed.

[0034] The invention further relates to a recording medium readable by means of a computer containing said computer program.

[0035] The invention also relates to a device for adapting the operation of a turboshaft engine, comprising at least one variable-geometry element configured to implement an analysis method according to the invention. The adaptation device comprises: - a module for detecting a malfunction in a turbocharger based on a deviation between the current value and the target position, and - a module for adapting the operation of the engine speed configured to allow the control of said at least one parameter by setting a setpoint value determined from said current value.

[0036] The detection module and the adaptation module can be implemented by the computer program as described previously.

[0037] The detection and adaptation modules may include communication means allowing the device to be inserted into a turboshaft engine.

[0038] In particular, the adaptation module advantageously includes means for transmitting the setpoint value of said parameter so as to This allows the parameter to be controlled, for example, by a fuel flow control system or an actuator regulating the engine shaft speed. Alternatively, a control system can be included in the adaptation module.

[0039] The invention also relates to an aircraft comprising: - a turboshaft engine comprising at least one variable geometry element, and - a device for adapting the operation of said turbomotor according to the invention so as to allow the adaptation of the operation of said turbomotor.

[0040] The said adaptation device may include at least one processor.

[0041] The aircraft may be a single-engine aircraft.

[0042] The turboshaft engine can be chosen from a twin-spool turboshaft engine, a triple-spool turboshaft engine, or an "Open Fan" type turboshaft engine.

[0043] This at least one variable geometry element may be chosen from among: one or more variable pitch stator blades, one or more relief valves, and / or a variable area nozzle. Of course, this list is neither exhaustive nor restrictive, and other variable geometry elements may be considered.

[0044] The aforementioned features and advantages, as well as others, will become apparent upon reading the detailed description that follows. This detailed description refers to the attached drawings. Brief description of the drawings

[0045] The attached drawings are schematic and are primarily intended to illustrate the principles of the presentation.

[0046] In these drawings, from one figure to another, identical elements (or parts of elements) are identified by the same reference symbols.

[0047] [Fig. 1] Figure 1 represents a functional architecture of an adaptation device according to an example of the invention,

[0048] [Fig. 2] Figure 2 represents the main steps of an adaptation process according to an example of the invention, which can be implemented by a device as illustrated in Figure 1,

[0049] [Fig. 3] Figure 3 illustrates an adaptation device according to the invention in its environment, according to a first embodiment,

[0050] [Fig. 4] Figure 4 illustrates an adaptation device according to the invention in its environment, according to a second embodiment,

[0051] [Fig. 5] Figure 5 represents the steps of an implementation method of the adaptation process according to the invention,

[0052] [Fig. 6] Figure 6 shows the steps of another implementation of the adaptation process according to the invention, and

[0053] [Fig. 7] Figure 7 illustrates an example of the hardware architecture of an adaptation device according to the invention. Description of the implementation methods

[0054] Figure 1 schematically illustrates an adaptation device 1 for the operation of a turboengine comprising at least one variable geometry element.

[0055] Device 1 is configured to implement a method for adapting the operation of said turbomotor 5, the implementation steps of which are illustrated in Figure 2.

[0056] The adaptation device 1 includes a detection module M10 configured to implement a step E10 of detecting a malfunction of said turbomachine arising from a deviation between the current value and the target position of the variable geometry element, and an adaptation module M20 of the engine speed operation configured to implement a step E20 of controlling at least one parameter on which the position of the variable geometry element is dependent by setting a setpoint value determined from said current value.

[0057] In certain embodiments, the adaptation device 1 has the hardware architecture of a computer, as shown in Figure 7. It should be noted that some elements of this architecture can be confused with corresponding elements of the turboengine.

[0058] More specifically, the adaptation device 1 may include a PC processor, a read-only memory ROM, a random-access memory RAM and communication means.

[0059] The read-only memory of the adaptation device 1 constitutes a recording medium readable by the processor and on which is recorded a computer program according to the invention, comprising instructions for the execution of the steps of the adaptation process 5 according to the invention detailed below and in particular illustrated in figure 2.

[0060] This computer program defines, in an equivalent manner, functional modules (software) of the adaptation device 1, such as, in particular, the detection module M10 and the adaptation module M20. The functions of these modules are described in more detail in the following description with reference to the steps of the adaptation process.

[0061] In the example illustrated in Figure 3, an adaptation device according to the invention is shown in its environment.

[0062] In this example, the adaptation device 1 is configured to adapt the operation of the turboshaft engine comprising the variable geometry element 2, controlled by a servo system 20 and following the setpoint law F2. At least one sensor 22 is configured to acquire the value of the current position Pcour of the variable geometry element. The position error ε represents the difference between a target position Pcib that one wishes to impose on the variable geometry element and the current value Pcour.

[0063] The variable geometry element 2 can notably be included in a turboshaft engine of an aircraft (not shown here).

[0064] The M10 detection module can be configured to determine the presence of a turbocharger malfunction. Alternatively, the M10 detection module includes communication means enabling it to receive information indicating the detection of a turbocharger malfunction. This information can be provided, for example, by the servo system 20 of the variable geometry element or an analysis module 6 as illustrated in figure 4.

[0065] In one embodiment, determining the presence of a turbocharger malfunction involves comparing the position error £ to a threshold value S, a position error £ strictly greater than the threshold value S being representative of the presence of a control failure corresponding to a turbocharger malfunction.

[0066] When a turbocharger malfunction is detected, the M20 adaptation module determines a setpoint value Vcons for said at least one parameter 3.

[0067] From the setpoint value Vcons, the adaptation module M20 triggers the control of parameter 3, by means of a parameter control system 30, comprising at least one sensor 32, so as to adapt the operation of the engine speed and therefore the operation of the turbocharger.

[0068] The servo system 30 can be included in the adaptation device 1.

[0069] Alternatively, the control system 30 is not included in the adaptation device 1, the adaptation device then comprising means of communication enabling the latter to trigger the control of at least one parameter 3, and preferably the stopping of said control.

[0070] We now describe embodiments of an adaptation method 5 according to the invention represented in figures 2, 5 and 6 which can in particular be implemented by means of an adaptation device 1 as described previously.

[0071] The detection of a malfunction of said turboengine preferably involves a comparison of the current value Pcour of the position of the variable geometry element with the target position Pcib, so as to obtain the deviation £ between the current value and the target position, then a comparison of the absolute value of this deviation £ with a threshold value S, a position error £ strictly greater than the threshold value S being representative of the presence of a malfunction of the turboengine.

[0072] The deviation £ can be advantageously obtained via the servo system 20 of the variable geometry element 2.

[0073] If the deviation £ is strictly greater than the threshold value S, a setpoint value can be determined for said at least one parameter so as to allow adaptation of the engine speed, said setpoint value being determined from the current position value of the variable geometry element.

[0074] This at least one parameter is linked to the setpoint law that determines the target position of the variable geometry element. "Linked" means that the parameter's value influences the target position of the variable geometry element. In other words, the target position can vary depending on the parameter's value. Furthermore, this at least one parameter is also linked to the engine speed; controlling this parameter allows for engine speed control.

[0075] Preferably, in parallel with the control of said at least one parameter 3, the control of said variable geometry element is maintained. In particular, this control may aim to make the current position value converge towards the target position.

[0076] Thus, in the case of a temporary failure, the actuators controlling the position of the variable geometry element can allow the convergence of the current position value towards the target position, the parallel control of said at least one parameter allowing to maintain an operation of the turbomachine which is adapted to the current position value.

[0077] The adaptation process may also include an interruption of the control of said parameter 3 when a stopping criterion is met as illustrated in figure 6.

[0078] The stopping criterion can be considered met when it is determined that the variable geometry element has the ability to reach the target position.

[0079] In particular embodiments, the stopping criterion is considered to be met when the deviation Σ, in absolute value, is no longer strictly greater than the threshold value S, the control of said at least one parameter 3 being then interrupted, advantageously allowing a return to normal operation of the turbomachine. Thus, at least one parameter 3 can be kept controlled as long as the current value Pcour of the position of the variable geometry element 2 is exclusively outside an allowed range of values, in other words as long as the difference between the current value and the target position £ is beyond the threshold value S.

[0080] Alternatively or additionally, determining the ability of the variable geometry element to reach the target position involves analyzing data from one or more sensors.

[0081] The sensor(s) could be a camera, a temperature sensor, or a pressure sensor.

[0082] All or part of the process according to the invention can be implemented by computer.

[0083] Example

[0084] An example of an implementation of the invention is described below in which said variable geometry element is a relief valve of a low pressure compressor of a turbomotor, also called VBV.

[0085] The discharge valve follows a setpoint law F2 such that Pcib_vBv = F2 (XN12R), depending among other things on the XN12R parameter. The XN12R parameter can be defined by XN12R = XN12 / ^(T12 / 288.115), with XN12 the rotation speed of the low pressure shaft in rpm, and T12 the temperature at the blower inlet, in K. The setpoint law F2 generally depends on other parameters, such as a total pressure at the blower inlet.

[0086] The presence of a malfunction can be detected by checking the condition: |Pcib_vBv - Pcour_vBv | > SVBV.

[0087] As soon as a malfunction is detected by the M10 detection module, the M20 adaptation module adjusts the turbocharger's engine speed by controlling, for example, the XN12R parameter. The setpoint value Vcons can be a Vcons_xNi2R setpoint value for the parameter XN12R and can be determined by inverting the setpoint law F2: Vcons_XN12R = Fs(Pcour_VBV) = F2- 1 (P cour_VBv).

[0088] This allows the engine speed to be controlled via the XN12R parameter, adapting the turbocharger's operation to the current value of the wastegate when it falls outside an acceptable range. The turbocharger remains operational, and the risk of damage such as compressor surge is minimized.

[0089] In parallel with the control of parameter XN12R, the relief valve is held in position. The actuators controlling the relief valve can therefore potentially modify the current position value, which can simultaneously vary the setpoint value Vcons_xNi2R for parameter XN12R.

[0090] Once the stopping criterion |Pcib_vBv -Pcour_vBv| < SVBV is met, the adaptation method can, in preferred embodiments of the invention, interrupt the control of said at least one parameter. Thus, the at least one parameter remains controlled as long as the current value of the position of the variable geometry element is exclusively outside an allowed range of values.

[0091] The target SVBV position can be maintained at its value as defined when the malfunction is detected. Alternatively, the target SVBV position can be redefined based on the current value of the relief valve position when the malfunction is detected. In other embodiments, the target SVBV position can be defined based on an actual parameter state, for example, one measured by sensor 32.

[0092] Although the present invention has been described with reference to specific embodiments, it is evident that modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various embodiments illustrated / mentioned can be combined in embodiments additional. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

[0093] The characteristics described with reference to a process are transposable, alone or in combination, to a device, and conversely, all the characteristics described with reference to a device are transposable, alone or in combination, to a process.

Claims

Demands

1. A method (5) for adapting the operation of a turboshaft engine comprising at least one variable geometry element (2) whose position is dependent on at least one parameter (3), the method comprising the following steps: a- detecting a malfunction of said turboshaft engine based on a deviation between the current value (Pcour) of said position and a target position (Pdb), b- adapting the engine speed of the turboshaft engine by controlling said at least one parameter (3), by setting a setpoint value (V CO ns) said parameter determined from said current value (Pcour).

2. Adaptation method according to claim 1 wherein the setpoint value comes from the inversion of a setpoint law (F2) controlling a servo control of the position of the variable geometry element.

3. Adaptation method according to any one of claims 1 or 2 comprising a selection of said setpoint value from a lookup table providing, for each position of a set of positions of the variable geometry element, a predefined setpoint value for said parameter.

4. Adaptation method according to any one of claims 1 to 3, the detection comprising a comparison of said deviation with respect to a threshold value(s).

5. Adaptation method according to any one of claims 1 to 4 comprising controlling the injection of a fuel flow into the turbocharger as a function of the setpoint value, the parameter preferably being related to a fuel flow and / or a rotational speed of a drive shaft of the turbocharger.

6. Adaptation method according to any one of claims 1 to 5, comprising interrupting the control of said at least one parameter as a function of a stopping criterion.

7. Computer program comprising code instructions which, when implemented, allow the execution of steps in a method for adapting the operation of a turboshaft engine according to any one of claims 1 to 6.

8. A device (1) for adapting the operation of a turboshaft engine comprising at least one variable geometry element (2) whose position is dependent on at least one parameter (3), the device comprising: - a detection module (M10) for a malfunction of said turbocharger based on a deviation between the current value (Pcour) of the position of said variable geometry element and a target position (P C it>), - an adaptation module (M20) of the operation of the turbomotor engine speed by controlling said at least one parameter (3) by setting a setpoint value of said parameter determined from said current value (P current).

9. Aircraft comprising: - a turboshaft engine comprising at least one variable geometry element (2), and - an adaptation device (1) according to claim 8 capable of adapting the operation of said turbomotor.

10. Aircraft according to claim 9 wherein at least one variable geometry element is selected from: one or more variable pitch stator blades, one or more discharge valves, and / or a variable section nozzle.

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