A design method for a broadband high-temperature flight casing vibration monitoring system

Abstract

The present invention belongs to the technical field of health monitoring of attachment casings of fixed-wing aircraft, and provides a method for designing an attachment casing vibration monitoring system. It mainly includes the design of attachment casing monitoring sensors (including high-frequency monitoring sensors and low-frequency monitoring sensors) and the design of attachment casing data acquisition and processing modules. Compared with the traditional attachment casing vibration monitoring scheme, the present invention utilizes newly developed high-frequency monitoring sensors and low-frequency monitoring sensors that meet the needs of broadband and high-temperature vibration monitoring of attachment casings, as well as corresponding data acquisition and processing modules, to achieve broadband vibration monitoring of the overall low-frequency vibration of the attachment casing and the high-frequency vibration generated by the internal components.

Description

Technical Field

[0001] The invention belongs to the technical field of health monitoring of flight attachment casings of fixed-wing aircraft, and relates to a design method of a broadband high-temperature flight attachment casing vibration monitoring system, which is applied to a flight attachment casing health monitoring system of a fixed-wing aircraft. Background Art

[0002] The auxiliary casing connects the engine and starter of the fixed-wing aircraft. During the starting process, the auxiliary power unit first drives the starter to operate, and the starter drives the engine turbine through the auxiliary casing until the engine is fully started; when the engine starts and can work independently, the starter is disengaged, and the engine drives the generator, oil pump and other accessories through the auxiliary casing to provide electricity and oil for the normal operation of the engine. The auxiliary casing plays a vital role in the engine starting process and the stable operation after starting.

[0003] The internal components of the flight attachment casing include gears, shafts and bearings. During their normal operation, they will be subjected to alternating loads and will produce rotor imbalance, rotor misalignment, gear wear, cracks, pitting and tooth breakage, bearing inner ring, outer ring, rolling element and retainer failures and other faults; these faults will generate high-frequency vibration signals; the flight attachment casing as a whole will also generate low-frequency vibration signals due to the influence of aircraft aerodynamic loads, landing impact, etc.; in order to ensure the normal operation of the flight attachment casing, it is necessary to monitor the vibration signals that reflect the health status of the flight attachment casing, and the vibration signal monitoring frequency range should cover low-frequency (as low as 1Hz) and high-frequency (up to 12kHz) signals to achieve broadband vibration monitoring of the internal components of the flight attachment casing and the overall vibration of the casing.

[0004] At present, most aircraft only monitor the rotation speed, lubricating oil pressure, lubricating oil temperature and lubricating oil metal chips for the flight accessory casing, and have not yet realized vibration monitoring of the flight accessory casing. Although vibration monitoring has been realized on some aircraft, due to the high working environment temperature of the flight accessory casing (which can reach above 200°C), the high and low frequency ranges of the flight accessory casing cannot be covered from the sensor to the vibration data acquisition and processing module, generally not exceeding 5Hz~5kHz, which cannot meet the needs of full-band monitoring of the flight accessory casing. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a design method for a broadband high-temperature flight attachment casing vibration monitoring system. The present invention designs a low-frequency monitoring sensor (low frequency can reach 1Hz) and a high-frequency monitoring sensor (high frequency can reach 12kHz) that can meet the vibration monitoring needs of the flight attachment casing under high temperature conditions. Combined with the data acquisition and analysis processing module, the broadband vibration signal of the flight attachment casing can be collected and analyzed, thereby realizing effective vibration monitoring of the flight attachment casing in the full frequency band.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A design method for a broadband high-temperature flight attachment casing vibration monitoring system mainly includes the design of flight attachment casing monitoring sensors (including high-frequency monitoring sensors and low-frequency monitoring sensors) and the design of flight attachment casing data acquisition and processing modules. For details, see the block diagram of the flight attachment casing vibration monitoring system. Figure 1 The specific steps include:

[0008] The first step is to design a high-frequency monitoring sensor

[0009] According to the analysis of the monitoring needs of the flight attachment casing, the high-frequency monitoring sensor is designed as a single-axis sensor, which is mainly used to monitor the vibration of internal rotating parts. The main monitoring direction is the radial direction of the gear drive shaft inside the flight attachment casing. Due to the small size of the flight attachment casing, a high-frequency monitoring sensor is used to monitor the high-frequency vibration signal of the flight attachment casing. Through the analysis of the dynamic characteristics of the flight attachment casing, the maximum monitoring frequency should not be less than 12kHz. In order to meet the frequency response index, the structural form of the center through hole installation is designed, and the piezoelectric annular shear structure is adopted.

[0010] The designed high-frequency monitoring sensor includes a first shell 1, a mass block 3 and a piezoelectric element 4 located inside the first shell 1, a first shell cover 2 located above the first shell 1, and a first connector 5. A cylindrical ring is provided at the center of the bottom surface of the first shell 1, and the annular piezoelectric element 4 is sleeved on the cylindrical ring and located on the bottom surface of the first shell 1. The annular mass block 3 is sleeved on the outer ring of the piezoelectric element 4 by interference fit. The first connector 5 is welded to the side of the first shell 1, and the first shell cover 2 is welded to the top of the first shell 1. When the high-frequency vibration monitoring sensor senses external vibration, the mass block 3 generates pressure to act on the piezoelectric element 4. After the piezoelectric element 4 is subjected to the pressure of the mass block 3, it generates a charge signal proportional to the external vibration and outputs it through the first connector 5.

[0011] The high-frequency monitoring sensor adopts an airtight sealing structure design and has a very long mean time between failures (MTBF). Considering the requirements of salt spray and acidic atmosphere, as well as the requirements of weight reduction, the materials of the first shell 1, the first shell cover 2 and the first connector 5 are all made of titanium alloy.

[0012] The structural diagram of the high-frequency monitoring sensor is shown in Figure 2 .

[0013] Step 2: Design a low-frequency vibration monitoring sensor

[0014] According to the analysis of the monitoring needs of the flying attachment casing, the low-frequency monitoring sensor is designed as a three-axis sensor, which is mainly used to monitor the low-frequency vibration of the flying attachment casing. The main monitoring directions are X, Y and Z, of which the X direction is the axial direction of the gear transmission shaft inside the flying attachment casing, the Y direction is the radial direction of the gear transmission shaft inside the flying attachment casing, and the Z direction is the normal direction of the plane formed by the X and Y directions. Due to the small size of the flying attachment casing, a low-frequency monitoring sensor is used to monitor the low-frequency vibration signal of the flying attachment casing. Through the analysis of the dynamic characteristics of the flying attachment casing, the frequency response range should be as low as 1Hz. In order to meet this performance indicator, a rectangular structure with double-hole interlocking installation and a variable capacitance sensitive unit are adopted to ensure the low-frequency performance of the sensor.

[0015] The designed low-frequency monitoring sensor includes a second shell 6, a second shell cover 7 located above the second shell 6, a first circuit unit 8, a second circuit unit 9, a third circuit unit 10 located inside the second shell 6, and a second connector 11 located on the side of the second shell 6. The three groups of circuit units are respectively installed on three mutually perpendicular sides inside the second shell 6 (the first circuit unit 8 is installed in the middle of the bottom surface inside the second shell 6, and the second circuit unit 9 and the third circuit unit 10 are installed on the inner walls of the two adjacent sides of the second shell 6, and the two adjacent sides are perpendicular to the bottom surface), and the second shell cover 7 is installed on the outer shell. The connector is installed on the side of the second shell 6 by 4 screws. The three groups of circuit units have the same structure and all contain core sensitive elements to sense acceleration vibration signals in three axes. When the low-frequency monitoring sensor senses external vibration, the sensitive elements in the three circuit units will generate charge signals proportional to the external vibration and output them through the connector.

[0016] The structural diagram of the low-frequency monitoring sensor is shown in Figure 3 .

[0017] The third step is to design the data acquisition and processing module of the flight attachment casing

[0018] The data acquisition and processing module of the flight attachment casing can synchronously process 1 vibration signal (charge signal) from the high-frequency monitoring sensor and 3 vibration signals (charge signals) from the low-frequency monitoring sensor:

[0019] First, a charge converter is used to convert one charge signal from the high-frequency monitoring sensor and three charge signals from the low-frequency monitoring sensor into voltage signals, thereby obtaining a voltage signal corresponding to the high-frequency monitoring sensor and a voltage signal corresponding to the low-frequency monitoring sensor;

[0020] Then, the voltage signal corresponding to the high-frequency monitoring sensor and the voltage signal corresponding to the low-frequency monitoring sensor are respectively passed through a high-frequency signal filter and a low-frequency signal filter, and then the voltage signals are respectively amplified through a high-frequency signal amplifier and a low-frequency signal amplifier;

[0021] Finally, the amplified information is converted into a digital signal through an A / D converter, and the high-frequency vibration signal and the low-frequency vibration signal are analyzed and processed respectively using the data analysis and processing module to achieve effective broadband vibration monitoring of the flight attachment casing.

[0022] For details, see the data processing flow of the flight case data acquisition and processing module. Figure 4 .

[0023] Furthermore, the high-frequency monitoring sensor adopts an airtight sealing structure design.

[0024] Furthermore, the materials of the first shell (1), the first shell cover 2 and the first connector 5 are all made of titanium alloy.

[0025] Furthermore, the X, Y and Z monitoring directions of the low-frequency monitoring sensor are: the X direction is the axial direction of the gear transmission shaft inside the flying attachment casing, the Y direction is the radial direction of the gear transmission shaft inside the flying attachment casing, and the Z direction is the normal direction of the plane formed by the X and Y directions.

[0026] The beneficial effects of the present invention are:

[0027] Compared with the traditional vibration monitoring scheme of the flight attachment casing, the present invention utilizes newly developed high-frequency monitoring sensors and low-frequency monitoring sensors that meet the wide-band vibration monitoring needs of the flight attachment casing, as well as corresponding data acquisition and processing modules, to achieve wide-band vibration monitoring of the overall low-frequency vibration of the flight attachment casing and the high-frequency vibration generated by internal components. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the block diagram of the flight casing vibration monitoring system;

[0029] Figure 2 This is a schematic diagram of the high-frequency monitoring sensor structure;

[0030] Figure 3 This is a schematic diagram of a low-frequency monitoring sensor;

[0031] Figure 4 This is the data collection and processing flow chart of the flight attachment casing;

[0032] Figure 5 This is a schematic diagram of a high-frequency monitoring sensor;

[0033] Figure 6 This is a schematic diagram of a low-frequency monitoring sensor;

[0034] Figure 7 This is a schematic diagram of the data acquisition and processing module of the flight attachment casing;

[0035] In the figure: 1 first shell, 2 first shell cover, 3 mass block, 4 piezoelectric element, 5 first connector, 6 second shell, 7 second shell cover, 8 first circuit unit, 9 second circuit unit, 10 third circuit unit, 11 second connector. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with specific embodiments.

[0037] A design method for a broadband high-temperature flight attachment casing vibration monitoring system mainly includes the design of flight attachment casing monitoring sensors (including high-frequency monitoring sensors and low-frequency monitoring sensors) and the design of flight attachment casing data acquisition and processing modules. Figure 1 The flight attachment casing vibration monitoring system of a certain type of aircraft is designed using the flight attachment casing vibration monitoring system design method, including: 1 single-axis high-frequency monitoring sensor, 1 three-axis low-frequency monitoring sensor and 1 set of flight attachment casing data acquisition and processing module. The schematic diagram is shown in Figure 5 , Figure 6 and Figure 7 The specific implementation plan is as follows:

[0038] The first step is to design a high-frequency monitoring sensor

[0039] According to the analysis of the monitoring needs of the flight attachment casing, the high-frequency monitoring sensor is designed as a single-axis sensor, which is mainly used to monitor the vibration of internal rotating parts. The main monitoring direction is the casing normal direction perpendicular to the axis of the gear transmission shaft inside the flight attachment casing. Due to the small size of the flight attachment casing, a high-frequency monitoring sensor is used to monitor the high-frequency vibration signal of the flight attachment casing. Through the analysis of the dynamic characteristics of the monitored object, the maximum monitoring frequency should not be less than 12kHz. In order to meet the frequency response index, the structural form of the center through hole installation is designed, and the piezoelectric annular shear structure is adopted.

[0040] The designed high-frequency monitoring sensor includes a first shell 1, a mass block 3 and a piezoelectric element 4 located inside the first shell 1, a first shell cover 2 located above the first shell 1, and a first connector 5. A cylindrical ring is provided at the center of the bottom surface of the first shell 1, and the annular piezoelectric element 4 is sleeved on the cylindrical ring and located on the bottom surface of the first shell 1. The annular mass block 3 is sleeved on the outer ring of the piezoelectric element 4 by interference fit. The first connector 5 is welded to the side of the first shell 1, and the first shell cover 2 is welded to the top of the first shell 1. When the high-frequency vibration monitoring sensor senses external vibration, the mass block 3 generates pressure to act on the piezoelectric element 4. After the piezoelectric element 4 is subjected to the pressure of the mass block 3, it generates a charge signal proportional to the external vibration and outputs it through the first connector 5.

[0041] The high-frequency monitoring sensor adopts an airtight sealing structure design, the signal is insulated from the shell, and has a very long mean time between failures (MTBF). Considering the requirements of salt spray and acidic atmosphere, as well as the requirements of weight reduction, the materials of the first shell 1, the first shell cover 2 and the first connector 5 are all made of titanium alloy.

[0042] Schematic diagram of high-frequency monitoring sensor, see Figure 5 The main indicators of high-frequency monitoring sensors are as follows:

[0043] a) Axial: single axis;

[0044] b) Range: ±500g;

[0045] c) Sensitivity: 10pC / g

[0046] d) Frequency response range: 5Hz~12kHz;

[0047] e) Overall dimensions: 25×25×18 (mm).

[0048] Step 2: Design a low-frequency vibration monitoring sensor

[0049] According to the analysis of the monitoring needs of the flight attachment casing, the low-frequency monitoring sensor is designed as a three-axis sensor, which is mainly used to monitor the low-frequency vibration of the flight attachment casing. The main monitoring directions are X, Y and Z, of which the X direction is the axial direction of the gear transmission shaft inside the flight attachment casing, the Y direction is the radial direction of the gear transmission shaft inside the flight attachment casing, and the Z direction is the normal direction of the plane formed by the X and Y directions. Due to the small size of the flight attachment casing, a low-frequency monitoring sensor is used to monitor the low-frequency vibration signal of the flight attachment casing. Through the analysis of the dynamic characteristics of the monitored object, the frequency response range should be as low as 1Hz. In order to meet this performance indicator, a rectangular structure with double-hole interlocking installation and a variable capacitance sensitive unit are adopted to ensure the low-frequency performance of the sensor.

[0050] The designed low-frequency monitoring sensor includes a second shell 6, a second shell cover 7 located above the second shell 6, a first circuit unit 8, a second circuit unit 9, a third circuit unit 10 located inside the second shell 6, and a second connector 11 located on the side of the second shell 6. The three groups of circuit units are respectively installed on three mutually perpendicular sides inside the second shell 6 (the first circuit unit 8 is installed in the middle of the bottom surface inside the second shell 6, and the second circuit unit 9 and the third circuit unit 10 are installed on the inner walls of the two adjacent sides of the second shell 6, and the two adjacent sides are perpendicular to the bottom surface), and the second shell cover 7 is installed on the outer shell. The connector is installed on the side of the second shell 6 by 4 screws. The three groups of circuit units have the same structure and all contain core sensitive elements to sense acceleration vibration signals in three axes. When the low-frequency monitoring sensor senses external vibration, the sensitive elements in the three circuit units will generate charge signals proportional to the external vibration and output them through the connector.

[0051] Schematic diagram of low frequency monitoring sensor, see Figure 6 The performance indicators of low-frequency monitoring sensors are as follows:

[0052] a) Axial: three axes;

[0053] b) Range: ±50g;

[0054] c) Sensitivity: 10pC / g

[0055] d) Frequency response range: 1Hz~800Hz;

[0056] e) Overall dimensions: 40×40×30 (mm).

[0057] The third step is to design the data acquisition and processing module of the flight attachment casing

[0058] The data acquisition and processing module of the flight attachment casing processes one vibration signal (charge signal) from the high-frequency monitoring sensor and three vibration signals (charge signals) from the low-frequency monitoring sensor. The charge is first converted into a voltage signal through a charge converter, and then the signals are respectively passed through a high-frequency signal filter and a low-frequency signal filter, and then amplified by a high-frequency signal amplifier and a low-frequency signal amplifier. The signals are then converted into digital signals through an A / D converter. The time domain and frequency domain data analysis and processing algorithms of the data analysis and processing module are used to analyze and process the high-frequency vibration signals and the low-frequency vibration signals respectively, so as to realize effective broadband vibration monitoring of the flight attachment casing.

[0059] Schematic diagram of the data acquisition and processing module of the flight attachment casing, see Figure 7 .

[0060] The above-described embodiments merely express the implementation methods of the present invention, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A design method for a vibration monitoring system for a flight attachment casing, characterized in that: The following steps are involved: The first step is to design a high-frequency monitoring sensor According to the analysis of the monitoring needs of the flight attachment casing, the high-frequency monitoring sensor is a single-axis sensor, which is used to monitor the vibration of the internal rotating parts, and the monitoring direction is the radial direction of the gear transmission shaft inside the flight attachment casing; a high-frequency monitoring sensor is used to monitor the high-frequency vibration signal of the flight attachment casing; through the analysis of the dynamic characteristics of the flight attachment casing, the maximum monitoring frequency should not be less than 12kHz; in order to meet the frequency response index, the structural form of the center through hole installation is designed, and the piezoelectric annular shear structure is adopted; The high-frequency monitoring sensor comprises a first shell (1), a mass block (3) and a piezoelectric element (4) located inside the first shell (1), a first shell cover (2) located above the first shell (1), and a first connector (5) located on the side of the first shell (1); a cylindrical ring is provided at the center of the bottom surface of the first shell (1), the annular piezoelectric element (4) is sleeved on the cylindrical ring and contacts the bottom surface of the shell (1), and the annular mass block (3) is sleeved on the outer ring of the piezoelectric element (4) by means of interference fit; when the high-frequency vibration monitoring sensor senses external vibration, the mass block (3) generates pressure acting on the piezoelectric element (4), and after the piezoelectric element (4) is subjected to the pressure of the mass block (3), it generates a charge signal proportional to the external vibration and outputs it through the first connector (5); Step 2: Design a low-frequency vibration monitoring sensor According to the analysis of the monitoring requirements of the flight attachment casing, the low-frequency monitoring sensor is designed as a three-axis sensor to monitor the low-frequency vibration of the flight attachment casing in the X, Y and Z directions; a low-frequency monitoring sensor is used to monitor the low-frequency vibration signal of the flight attachment casing; through the analysis of the dynamic characteristics of the flight attachment casing, the frequency response range should be as low as 1Hz; in order to meet this performance indicator, a double-hole interlocking rectangular structure and a variable capacitance sensitive unit are used to ensure the low-frequency performance of the sensor; The low-frequency monitoring sensor comprises a second shell (6), a second shell cover (7) located above the second shell (6), a first circuit unit (8), a second circuit unit (9), a third circuit unit (10) located inside the second shell (6), and a second connector (11) located on the side of the shell (6); the three groups of circuit units are respectively installed on three mutually perpendicular side surfaces inside the second shell (6), the first circuit unit (8) is installed in the middle of the bottom surface inside the second shell (6), and the second circuit unit (9) and the third circuit unit (10) are installed on the inner walls of two adjacent side surfaces of the second shell (6), and the two adjacent side surfaces are perpendicular to the bottom surface; the three groups of circuit units have the same structure and all contain core sensitive elements to sense acceleration vibration signals in three axes. When the low-frequency monitoring sensor senses external vibration, the sensitive elements in the three circuit units will generate charge signals proportional to the external vibration and output them through the connector; The third step is to design the data acquisition and processing module of the flight attachment casing The data acquisition and processing module of the flight attachment casing can synchronously process 1 vibration signal from the high-frequency monitoring sensor and 3 vibration signals from the low-frequency monitoring sensor: First, a charge converter is used to convert one charge signal from the high-frequency monitoring sensor and three charge signals from the low-frequency monitoring sensor into voltage signals, thereby obtaining a voltage signal corresponding to the high-frequency monitoring sensor and a voltage signal corresponding to the low-frequency monitoring sensor; Then, the voltage signal corresponding to the high-frequency monitoring sensor and the voltage signal corresponding to the low-frequency monitoring sensor are respectively passed through a high-frequency signal filter and a low-frequency signal filter, and then the voltage signals are respectively amplified through a high-frequency signal amplifier and a low-frequency signal amplifier; Finally, the amplified voltage signal is converted into a digital signal through an A / D converter, and the high-frequency vibration signal and the low-frequency vibration signal are analyzed and processed respectively using the data analysis and processing module to achieve effective broadband vibration monitoring of the flight attachment casing.

2. The design method of a flight attachment casing vibration monitoring system according to claim 1 is characterized in that: The high-frequency monitoring sensor adopts an airtight sealing structure design.

3. The design method of a flight attachment casing vibration monitoring system according to claim 1, characterized in that: The materials of the housing (1), housing cover (2) and connector (5) are all titanium alloy materials.

4. The design method of a flight attachment casing vibration monitoring system according to claim 1, characterized in that: The X, Y and Z monitoring directions of the low-frequency monitoring sensor are: the X direction is the axial direction of the gear transmission shaft inside the flying accessory casing, the Y direction is the radial direction of the gear transmission shaft inside the flying accessory casing, and the Z direction is the normal direction of the plane formed by the X and Y directions.

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