Fuel parameter-based engine rotating speed non-following fault diagnosis method

Abstract

The invention discloses an engine rotating speed non-following fault diagnosis method based on fuel parameters, which comprises the following steps: acquiring measured values through an engine sensor, the measured values comprising a fuel flow given value, a fuel flow feedback value and a current engine rotating speed; engine function related design values are obtained, wherein the design values comprise the engine rotating speed design maximum value and the fault judgment parameter threshold value; carrying out data conversion according to the measured value, and counting the fault time length; calculating fault judgment parameters according to the fault time length, wherein the fault judgment parameters comprise a main fuel oil following deviation maximum value WFgs; and judging whether a rotating speed non-following fault occurs or not according to the fault judgment parameter and a fault judgment parameter threshold value. According to the technical scheme, the rotating speed non-following fault diagnosis algorithm can be perfected and corrected, and compared with an existing rotating speed non-following fault diagnosis scheme, the method can remarkably eliminate interference factors caused by different flight states and remarkably improve the accuracy of fault isolation and diagnosis results.

Description

Technical Field

[0001] The present invention relates to the field of aviation engine health management, and in particular to a fault diagnosis method for engine speed non-following based on fuel parameters. Background Art

[0002] The main pump regulator is the core of the aircraft engine control system. It adjusts the engine's fuel supply by sensing two parameters: atmospheric temperature pressure and compressor air pressure, thereby ensuring the safety, stability and reliability of the aircraft in all flight states. To ensure that the aircraft can respond quickly and be put into combat, it is necessary to ensure that the engine acceleration phase is fault-free. Aircraft engine fault diagnosis technology is one of the key technologies in the development of aircraft engine maintenance strategies from planned maintenance to dynamic condition-based maintenance. It aims to monitor and isolate faults in real time based on the parameters measured by engine sensors.

[0003] Domestic related research and development enterprises mainly extract fault information from historical engine test data and a small amount of fault data, and establish fault diagnosis methods based on historical data. In actual environments, the fuel supply during the engine acceleration phase is determined by the acceleration controller of the main pump regulator. In view of the influence of the uncertainty of the engine state when the engine speed does not follow the throttle, the existing method of establishing fault diagnosis based on historical data is not accurate enough for fault diagnosis and still requires manual screening and confirmation. Therefore, a technical solution is needed to achieve accurate positioning of engine faults without being affected by the flight status and to realize speed failure diagnosis. Summary of the invention

[0004] To achieve the above object, the present application provides a method for diagnosing a fault of an engine speed failure based on a fuel parameter, comprising:

[0005] Obtaining measurement values ​​through engine sensors, the measurement values ​​including: a fuel flow set value, a fuel flow feedback value and a current engine speed; obtaining engine function-related design values, the design values ​​including a maximum engine speed design value and a fault judgment parameter threshold;

[0006] Perform data conversion based on the measured values ​​and calculate the length of the fault time;

[0007] Calculate the fault judgment parameters according to the fault time length, the fault judgment parameters include the maximum value of the main fuel following deviation WF_gs;

[0008] Whether a speed non-following fault occurs is determined based on the fault judgment parameter and the fault judgment parameter threshold.

[0009] The data conversion includes the following steps:

[0010] Calculating a first fuel flow parameter, where the first fuel flow parameter is calculated and generated by a given fuel flow value;

[0011] A speed non-following fault counter is generated according to the first fuel flow parameter and the fuel flow feedback value.

[0012] Further, generating a speed non-following fault counter includes:

[0013] Get the internal fuel flow feedback value at a time point;

[0014] If the fuel flow feedback value is less than the first fuel flow parameter, the speed non-following fault count at the time point is set to 1, otherwise the speed non-following fault count is set to 0;

[0015] The time point and the corresponding non-following fault count are stored to form a speed non-following fault counter.

[0016] The fault time length is generated based on the length of time when the count value of the speed non-following fault counter is 1.

[0017] Furthermore, when the maximum value of the main fuel following deviation WF_gs is reached, it is determined whether the ratio of the current engine speed to the designed maximum value of the engine speed is greater than or equal to 70%. If so, the fault time length is multiplied by the current engine speed to obtain the maximum value of the main fuel following deviation WF_gs. Otherwise, it is determined that no engine failure occurs and the maximum value of the main fuel following deviation WF_gs is not calculated.

[0018] Further, when the fault judgment parameter is greater than the fault judgment parameter threshold, it is determined that a speed non-following fault occurs; otherwise, it is determined that a speed non-following fault does not occur.

[0019] According to the present invention, the speed non-following fault diagnosis algorithm can be improved and corrected. Compared with the existing speed non-following fault diagnosis scheme, the use of this method can significantly eliminate the interference factors caused by different flight states and significantly improve the accuracy of fault isolation and diagnosis results. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a flow chart of a method for diagnosing a fault of an engine speed not following according to an embodiment of the present invention;

[0021] Figure 2 is a schematic diagram of a normal engine operation diagnosis result provided according to an embodiment of the present invention;

[0022] Figure 3 is a schematic diagram of an engine speed non-following state provided according to an embodiment of the present invention;

[0023] Figure 4is a schematic diagram of an engine speed non-following fault diagnosis result provided according to an embodiment of the present invention;

[0024] Figure 5 It is a schematic diagram of the fault diagnosis result of the engine speed not following in the existing method. DETAILED DESCRIPTION

[0025] The present invention provides a method for combining dynamic data such as engine speed with design data, calculating the maximum value of the main fuel following deviation in a program, and realizing speed non-following fault diagnosis. Through this method, speed non-following fault isolation and diagnosis can be accurately realized.

[0026] The specific implementation of the present invention is described in detail below with reference to the accompanying drawings.

[0027] Figure 1 A fault diagnosis method flow for engine speed failure is provided, as shown in the figure, including the following steps:

[0028] Step S100: obtaining measurement values ​​through engine sensors; obtaining design values ​​related to engine functions;

[0029] The measured values ​​that can be obtained through the engine sensors include: fuel flow set value, fuel flow feedback value and current engine speed;

[0030] The engine function-related design values ​​include the maximum engine speed design value and a predefined parameter threshold: a fault judgment parameter threshold. In actual applications, the fault judgment parameter threshold is defined based on experience, for example, set to 50.

[0031] Step S110: performing data conversion according to the measured value and calculating the fault time length;

[0032] The data conversion in this step can be realized by running the data conversion algorithm program in MATLAB. The conversion process can obtain parameters such as the main fuel following deviation and deviation duration. The conversion process specifically includes the following steps:

[0033] 1) Calculating the first fuel flow parameter: The first fuel flow parameter is a parameter related to a given value, and is generated by multiplying a given coefficient by a given value of the fuel flow; wherein the given coefficient is usually assigned a value of 0.99;

[0034] 2) Generate a speed non-following fault counter according to the first fuel flow parameter and the fuel flow feedback value:

[0035] Specifically, the process of generating the speed non-following fault counter includes:

[0036] Get the fuel flow feedback value at a time point;

[0037] Compare the fuel flow feedback value and the first fuel flow parameter: if the fuel flow feedback value is less than the first fuel flow parameter, set the speed non-following fault count value at the time point to 1, otherwise set the speed non-following fault count to 0;

[0038] The time points in the above comparison process and the corresponding non-following fault counts are stored to form a speed non-following fault counter.

[0039] In the subsequent judgment application, when the speed non-following fault count is 0, it can be judged that the engine has no speed non-following fault;

[0040] Step S120: calculating fault judgment parameters according to the fault time length, wherein the fault judgment parameters include the maximum value of the main fuel following deviation WF_gs;

[0041] The fault time length in this step is generated based on the time length when the speed does not follow the fault counter and the count is 1;

[0042] When calculating the fault judgment parameters, determine whether the ratio of the current engine speed to the maximum design engine speed is greater than or equal to 70%: if so, calculate the maximum value of the main fuel following deviation WF_gs, that is: WF_gs = fault time length × current engine speed; otherwise, determine that no non-following fault has occurred.

[0043] In practical applications, when the engine is at or below the slow speed, the sensitivity of the interference factors to the engine performance will be very prominent: if a small state change occurs, such as a small change in the fuel flow rate, the engine speed may also change greatly, and at this time, the fault diagnosis of the engine speed not following is of no practical significance. Therefore, in the present invention, only when the ratio of the current engine speed to the maximum design engine speed is greater than or equal to a certain fixed value (such as 70%), the fault diagnosis is performed to eliminate the influence of interference factors.

[0044] Step S130: judging whether a speed non-following fault occurs according to the fault judgment parameter and the fault judgment parameter threshold.

[0045] Specifically, if the fault judgment parameter at the time point is greater than the fault judgment parameter threshold, it is determined that a speed non-following fault occurs at the time point; otherwise, it is determined that a speed non-following fault does not occur.

[0046] The diagnostic method of this step is essentially to judge based on the given speed and actual speed of the engine. Figure 3 A comparison chart of the given engine speed and the actual engine speed when the engine speed does not follow the fault diagnosed according to WF_gs is provided, where the vertical axis is the speed, N2 represents the actual speed, and N2dem represents the given speed. It can be seen that when the speed does not follow the fault is measured, there is a large difference between the actual speed and the given speed.

[0047] For example, the fault judgment parameter threshold is defined in advance to be equal to 50, such as Figure 2 As shown: the horizontal axis is the running time, and the vertical axis is the parameter for fault judgment obtained according to this method (maximum value of the main fuel following deviation WF_gs). Since the maximum value of the main fuel following deviation WF_gs is 35, it does not exceed the fault judgment parameter threshold. Figure 2 During the time period shown, the engine does not have a speed failure. When the maximum value of the main fuel following deviation WF_gs is greater than 50, such as Figure 4 As shown in the peak point of the curve, at 250s, WF_gs reaches 250, which greatly exceeds the fault judgment parameter threshold. It can be located that the speed non-following fault occurred at this time point. It can be seen that the fault diagnosis method provided by the present invention can accurately diagnose the speed non-following fault and accurately locate the time when the fault occurs, which is convenient for finding problems in the control of the main pump device and other aspects.

[0048] Figure 5 A schematic diagram of the diagnosis results of the existing method for diagnosing the speed non-following fault is provided. The horizontal axis in the figure is the running time, and the vertical axis is the parameter used to judge the fault obtained according to the existing technology. There are too many pulses in the figure, so the time when the fault occurs cannot be accurately located.

[0049] In general, the present invention realizes fault diagnosis based on a comprehensive algorithm by acquiring and converting data: first, the engine fuel flow information is acquired and converted to construct a speed non-following fault counter. Then, the length of each segment of the number in the counter is counted, and the obtained length and the engine speed at this time are combined to generate a parameter for fault judgment, which is then compared with the threshold value. The method can achieve accurate isolation of the engine speed fault, solving the problem of inaccurate fault diagnosis positioning caused by the existing speed non-following fault diagnosis method and interference from the engine state.

[0050] The above disclosures are only several specific embodiments of the present invention; however, the present invention is not limited thereto, and any changes that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A method for diagnosing a fault of an engine speed failure based on fuel parameters, characterized in that: include: Obtaining measurement values ​​through engine sensors, the measurement values ​​including: a fuel flow set value, a fuel flow feedback value and a current engine speed; obtaining engine function-related design values, the design values ​​including a maximum engine speed design value and a fault judgment parameter threshold; Perform data conversion according to the measured values ​​and calculate the length of the fault time; Calculate a fault judgment parameter according to the fault time length, wherein the fault judgment parameter includes a main fuel following deviation maximum value WF_gs; It is determined whether a speed non-following fault occurs according to the fault judgment parameter and the fault judgment parameter threshold.

2. The fault diagnosis method according to claim 1, characterized in that: The data conversion comprises the following steps: Calculating a first fuel flow parameter, wherein the first fuel flow parameter is calculated and generated by a given fuel flow value; A speed non-following fault counter is generated according to the first fuel flow parameter and the fuel flow feedback value.

3. The fault diagnosis method according to claim 2, characterized in that: The speed non-following fault generating calculator comprises: Get the internal fuel flow feedback value at a time point; If the fuel flow feedback value is less than the first fuel flow parameter, the speed non-following fault count at the time point is set to 1, otherwise the speed non-following fault count is set to 0; The time point and the corresponding non-following fault count are stored to generate a rotation speed non-following fault counter.

4. The fault diagnosis method according to claim 3, characterized in that: The fault time length is generated based on the length of time when the count value of the speed non-following fault counter is 1.

5. The fault diagnosis method according to claim 1, characterized in that: Determine whether the ratio of the current engine speed to the maximum design engine speed is greater than or equal to 70%. If so, multiply the fault time length by the current engine speed to obtain the maximum main fuel following deviation WF_gs. Otherwise, determine that no non-following fault has occurred.

6. The fault diagnosis method according to claim 1, characterized in that: If the fault judgment parameter is greater than the fault judgment parameter threshold, it is determined that a speed non-following fault occurs; otherwise, it is determined that a speed non-following fault does not occur.

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