Device and method for controlling the operation of turboshaft engines to accommodate failures in the control systems of variable geometry elements

Abstract

Device and method for controlling the operation of turboshaft engines for accommodating failures in the control of variable geometry elements. Device and method for adapting the operation of a turboshaft engine comprising a variable geometry element whose position depends on at least one parameter, enabling the detection of a failure in the control of the variable geometry element and the adaptation of the turboshaft engine's operation by controlling said at least one parameter by setting a setpoint value determined from the current value of the variable geometry element's position so as to impose a specific engine speed. Figure for the abstract: Fig. 1.

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 control instructions or other external conditions. The control of these variable geometry elements is achieved by position control of all or part of said elements. 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 a malfunction of an actuator.

[0004] In response to these fault detections, a warning message is classically sent 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 cause 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 also temporary, for example when the variable-pitch element's position does not change as rapidly as the target position, for example during turboshaft engine transients. Unfortunately, regardless of the failure, the pilot will slow down and then shut down the turboshaft engine.

[0007] There is therefore 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 a sufficient thrust level. In general, it would be desirable to improve the management of control system failures in a turboshaft engine.

[0008] The invention aims to meet all or part of these needs. Description of the invention

[0009] 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 is dependent on at least one parameter, the method comprising the following steps: a) detection of a malfunction of said turbocharger based on a deviation between the current value of said position and a target position, b) adaptation of the operation of the turbomotor engine speed by controlling said at least one parameter by setting a setpoint value determined from said current value.

[0010] The adaptation method according to the invention has the advantage of allowing flight to continue while minimizing or even preventing degradation of the turboshaft engine's condition. In particular, the method makes it possible to maintain the turboshaft engine 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.

[0011] The detection of the malfunction may result from an abnormally slow variation 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 variation in the value of the position of said variable timing element.

[0012] The method according to the invention advantageously allows adaptation of the operation of the turbomotor regardless of the origin of the malfunction.

[0013] Preferably, the variable-positioning element is kept in position in parallel with the control of said at least one parameter.

[0014] For example, it is possible, thanks to the invention, 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.

[0015] The invention can limit the risk of damage to the turbocharger while allowing a return to normal operation, avoiding permanent idling or a complete shutdown of the turbocharger. In particular, in the case of a temporary malfunction, for example, in the case of an abnormally slow change in speed, the implementation of the invention makes it possible to manage the transient regime by adapting the engine speed to the faulty variable timing element and, ultimately, reaching the target position and thus returning to normal turboshaft engine operation. In the event of a permanent malfunction, for example when the position value of the variable timing element is locked, the invention can maintain turboshaft engine thrust and, in particular, facilitate flight stability.

[0016] In general, the invention allows, 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, the triggering of a control system that imposes an engine speed adapted to the current value of said variable geometry element. The operation of the turbocharger is then defined according to the current position of said 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, the setpoint value being adapted according to the current value.

[0017] In particular embodiments of the invention, the target position of the variable geometry element is recalculated from an effective value for said at least one parameter, the control of said at least one parameter making it possible to maintain a position of the variable geometry element as close as possible to the current position value of the variable geometry element at the time of malfunction detection. This makes it possible to maintain a thrust similar to the thrust of the engine at the time of malfunction detection.

[0018] 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 its value as defined at the time the malfunction was detected, potentially making it possible for the engine speed to converge to the desired operation before the malfunction was detected.

[0019] 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.

[0020] In particular embodiments of the invention, the adaptation method comprises 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.

[0021] Alternatively, the setpoint value can be calculated over time as a function of the current value.

[0022] Detecting a malfunction may involve comparing the deviation to a threshold value. The threshold value is not limited to a fixed value; it may 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 may be compared to the absolute value of the deviation. The threshold value preferably depends on the variable geometry element.

[0023] The adaptation method may further include a step of controlling the injection of a fuel flow into the turbocharger as a function of the setpoint value, the parameter being for example related to a fuel flow or a rotational speed of a motor shaft.

[0024] In preferred embodiments of the invention, the method includes 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.

[0025] The stopping criterion can be considered to have been 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.

[0026] This interruption advantageously allows the turbocharger to resume normal operation, particularly in the event of a temporary failure, for example, in the case of a seizure that could slow the actuation capabilities of the variable geometry element. Normal operation refers to the operation of the turbocharger before the fault is detected, specifically the normal operation corresponding to the operation of the turbocharger before the parameter control is activated.

[0027] Determining the ability of the variable geometry element to reach the target position can be achieved by analyzing data acquired by sensors in order to identify the disappearance of the cause of the malfunction. The analysis may include determining a change in environmental conditions and / or an operating state of the variable geometry element or of all or part of a control system controlling the position of said variable geometry element, the sensors which may include at least one of the following: a temperature sensor, a pressure sensor, a camera.

[0028] Alternatively or additionally, said determination may include comparing a difference between the current position value and the target value.

[0029] 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.

[0030] All or part of the steps of the adaptation process can be implemented by computer, preferably all the steps of the process are implemented by computer.

[0031] 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 turbomotor according to the invention, this program being capable of being implemented in a control module.

[0032] The invention further relates to a recording medium readable by means of a computer comprising said computer program.

[0033] 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.

[0034] The detection module and the adaptation module can be implemented by the computer program as described above.

[0035] 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.

[0036] Said adaptation device may include at least one processor.

[0037] The aircraft may be a single-engine aircraft.

[0038] The turboshaft engine can be chosen from a twin-spool turboshaft engine, a triple-spool turboshaft engine, an "Open Fan" type turboshaft engine.

[0039] Said at least one variable geometry element may be selected from: one or more variable pitch straightener blades, one or more discharge valves, and / or a variable-section nozzle. Of course, this list is neither exhaustive nor limiting, and other variable-geometry elements can be considered.

[0040] The aforementioned features and advantages, as well as others, will become apparent from the detailed description that follows. This detailed description refers to the accompanying drawings. Brief description of the drawings

[0041] The attached drawings are schematic and are intended primarily to illustrate the principles of the exposition.

[0042] On these drawings, from one figure to another, identical elements (or parts of elements) are identified by the same reference signs.

[0043] [Fig-1] Fig. 1 represents a functional architecture of a device adaptation according to an example of the invention,

[0044] [Fig.2] Fig.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 Fig.1.

[0045] [Fig.3] Figure [Fig.3] illustrates an adaptation device according to the invention in its environment, according to a first embodiment,

[0046] [Fig.4] Figure [Fig.4] illustrates an adaptation device according to the invention in its environment, according to a second embodiment,

[0047] [Fig.5] Fig.5 represents the steps of an implementation method of the adaptation process according to the invention,

[0048] [Fig. 6] Figure 6 shows the steps of another embodiment of the adaptation process according to the invention, and

[0049] [Fig.7] Fig.7 illustrates an example of the material architecture of an adaptation device according to the invention. Description of the implementation methods

[0050] Fig. 1 schematically illustrates an adaptation device 1 for the operation of a turbomotor comprising at least one variable geometry element.

[0051] Device 1 is configured to implement a method for adapting the operation of said turbomotor 5, the implementation steps of which are illustrated in [Fig.2].

[0052] The adaptation device 1 comprises a detection module M10 configured to implement a step E10 for detecting a malfunction of said turbocharger arising from a deviation between the current value and the target position of the variable geometry element, and an engine speed operation adaptation module M20 configured to implement a step E20 for controlling the minus a parameter on which the position of the variable geometry element depends by setting a setpoint value determined from said current value.

[0053] In particular embodiments, the adaptation device 1 has the hardware architecture of a computer, as shown in [Fig. 7]. It should be noted that certain elements of this architecture may be confused with corresponding elements of the turboshaft engine.

[0054] More specifically, the adaptation device 1 may include a PC processor, a read-only memory ROM, a random-access memory RAM and communication means.

[0055] 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 [Fig.2],

[0056] This computer program equivalently defines 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.

[0057] In the example illustrated in [Fig.3], an adaptation device according to the invention is shown in its environment.

[0058] 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 e represents the difference between a target position Pcib that one wishes to impose on the variable geometry element and the current value Pcour.

[0059] The variable geometry element 2 can in particular be included in a turboshaft engine of an aircraft (not shown here).

[0060] The detection module M10 can be configured to determine the presence of a turbocharger malfunction. Alternatively, the detection module M10 includes communication means enabling it to receive information indicating the detection of a turbocharger malfunction. The information can, for example, be provided by the servo system 20 of the variable geometry element or an analysis module 6 as illustrated in [Fig. 4].

[0061] In one embodiment, determining the presence of a turbocharger malfunction involves comparing the position error e to a threshold value S, a position error e strictly greater than the threshold value S being representative of the presence of a servo failure corresponding to a malfunction of the turbomotor.

[0062] When a turbocharger malfunction is detected, the M20 adaptation module determines a setpoint value Vcons for said at least one parameter 3.

[0063] From the setpoint value Vcon s, 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.

[0064] The servo system 30 can be included in the adaptation device 1.

[0065] Alternatively, the control system 30 is not included in the adaptation device 1, the adaptation device then comprising communication means enabling the latter to trigger the control of at least one parameter 3, and preferably the stopping of said control.

[0066] Embodiments of an adaptation method 5 according to the invention are now described, shown in Figures 2, 5 and 6, which can in particular be implemented by means of an adaptation device 1 as described above.

[0067] The detection of a malfunction of said turbomotor preferably includes 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 e between the current value and the target position, then a comparison of the absolute value of this deviation e with a threshold value S, a position error e strictly greater than the threshold value S being representative of the presence of a malfunction of the turbomotor.

[0068] The deviation e can be advantageously obtained via the servo system 20 of the variable geometry element 2.

[0069] If the deviation e 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.

[0070] Said at least one parameter is a parameter linked to the setpoint law determining the target position of the variable geometry element. By "linked" it is understood that the value of the parameter influences the value of the target position of the variable geometry element. In other words, depending on the value of the parameter, the value of the target position can vary. Furthermore, said at least one parameter is also linked to the engine speed, the control of said parameter enabling the control of the engine speed.

[0071] 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 system can aim to make the current position value converge towards the target position.

[0072] 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 turbomotor which is adapted to the current position value.

[0073] The adaptation method may further include an interruption of the control of said parameter 3 when a stopping criterion is met as illustrated in [Fig.6].

[0074] The stopping criterion can be considered to have been met when it is determined that the variable geometry element has the ability to reach the target position.

[0075] In particular embodiments, the stopping criterion is considered to be met as soon as the deviation e, 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, the at least one parameter 3 can remain 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 deviation between the current value and the target position e is beyond the threshold value S.

[0076] Alternatively or additionally, determining the ability of the variable geometry element to reach the target position involves analyzing data from one or more sensors.

[0077] The sensor(s) may be among a camera, a temperature sensor, a pressure sensor.

[0078] All or part of the process according to the invention can be implemented by computer. Examples

[0079] 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.

[0080] 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 / V(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.

[0081] The presence of a malfunction can be detected by checking the condition: IPCib _vbv — Core _vbvI > Svbv.

[0082] As soon as a malfunction is detected by the detection module M10, the adaptation module M20 adapts the turbocharger's engine speed by controlling, for example, the parameter XN12R. The setpoint value Vcons can be a setpoint value Vcons xnhr for the parameter XN12R and can be determined by inverting the setpoint law F2: VCOns _XN12R = F3(Pcour _VBv) = F2 *(Pcour _VBv)*

[0083] This allows the engine speed to be imposed via the control of parameter XN12R so as to adapt the operation of the turbocharger to the current value of the wastegate as soon as this value falls outside an permissible range. The turbocharger then remains operational and the risks of damage such as compressor surge are minimized.

[0084] In parallel with the control of the XN12R parameter, the discharge valve is held in a controlled position. The actuators controlling the discharge valve can therefore optionally modify the current position value, which can simultaneously vary the setpoint value Vcons xnhr for the XN12R parameter.

[0085] Once the stopping criterion IPcib _vbv -PCOur _vbvI < 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.

[0086] The target position SVbv can be maintained at its value as defined upon malfunction detection. Alternatively, the target position Svbv can be redefined according to the current value of the relief valve position at the time of malfunction detection. In other embodiments, the target position Svbv can be defined according to an actual state of the parameter, for example, measured by sensor 32.

[0087] 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 additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than a restrictive sense.

[0088] 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. Method of adapting (5) 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- detection of a malfunction of said turboshaft engine from a deviation between the current value (Pcour) of said position and a target position (Pcib), b- adaptation of the operation of the engine speed of the turboshaft engine by controlling said at least one parameter (3), by setting a setpoint value (Vcons) of 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 (e).

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, enable 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. Adaptation device (1) of the operation of a turboshaft engine comprising at least one variable geometry element, the device comprising: - a detection module (M10) of a malfunction of said turboshaft engine from a deviation between the current value (Pcour) of the position of said variable geometry element and a target position (Pcib), - an adaptation module (M20) of the operation of the engine speed of the turboshaft engine by controlling said at least one parameter (3) by setting a setpoint value.

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

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 area nozzle.

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