Pitch angle measurement structure for a blade, measurement method, and aircraft engine

Abstract

This application provides a blade pitch angle measurement structure, measurement method, and aero-engine. The blade is rotatably connected to a hub, with the rotation axis being the Y-axis. The pitch angle measurement structure includes visual markers and an optical measuring device. The visual markers include a first marker, a second marker extending circumferentially along the Y-axis, and a third marker extending axially along the Y-axis. The first, second, and third markers form a pattern. In the pattern, the extension direction of the third marker intersects the first marker at a first intersection point and the second marker at a second intersection point. The distance between the first and second intersection points changes synchronously with the blade pitch angle. The optical measuring device is configured to acquire an image of the pattern, thereby determining the blade pitch angle based on the distance between the first and second intersection points in the pattern.

Description

Technical Field

[0001] This application relates to the field of angle measurement technology, specifically to a blade pitch angle measurement structure, measurement method, and aero-engine. Background Technology

[0002] Aero engines achieve high aerodynamic performance and reduce noise by configuring blades with variable pitch angles and adjusting the blade pitch angles according to different operating conditions. Real-time measurement of the blade pitch angles during engine operation provides crucial data for monitoring and controlling flight status.

[0003] Currently, non-contact measurement of blade pitch angle in this field is usually achieved using a measurement structure composed of a sensing component and an induction component made of ferromagnetic material, such as a Hall sensor. The principle is that the sensing component is displaced as the pitch angle changes, thereby causing a change in the magnetic field. The induction component detects the magnetic field and converts it into an electrical signal. The blade pitch angle is indirectly calculated based on the relationship between the electrical signal and the position of the sensing component.

[0004] However, the technical problems with the above-described solutions include, but are not limited to: the sensing component itself occupies space and may adversely affect the working performance of the blades; furthermore, since the blade pitch angle adjustment range is relatively large, generally about 100°, the sensing component requires a correspondingly large amount of space to cover the entire adjustment range, which is not conducive to the compact arrangement of the engine's internal structure. If the space for movement of the sensing component is limited, it will lead to measurement dead zones within the adjustment range; and changes in the engine's operating state, vibration, etc., may cause the position of the sensing component to deviate, adversely affecting the sensing of the sensing component and leading to measurement deviations.

[0005] Therefore, there is a need in the field to develop new pitch angle measurement structures, measurement methods, and aero engines to solve at least one or a combination of the above technical problems. Summary of the Invention

[0006] The purpose of this application is to provide a structure for measuring the pitch angle of blades.

[0007] Another objective of this application is to provide a method for measuring the blade pitch angle.

[0008] Another objective of this application is to provide an aircraft engine.

[0009] A blade pitch angle measurement structure according to a first aspect of this application; wherein the blade is rotatably connected to a hub, and the rotation axis is a Y-axis; the blade pitch angle measurement structure includes visual markers and an optical measuring device; wherein the visual markers include: a first marker and a second marker extending circumferentially along the Y-axis; a third marker extending axially along the Y-axis; and the first marker, the second marker, and the third marker form a pattern; in the pattern, the extension direction of the third marker intersects the first marker at a first intersection point and the second marker at a second intersection point; the distance between the first intersection point and the second intersection point changes synchronously with the blade pitch angle; the optical measuring device is configured to acquire an image of the pattern to determine the blade pitch angle based on the distance between the first intersection point and the second intersection point in the pattern.

[0010] The pitch angle measurement structure described above replaces the traditional electromagnetic measurement structure with visual markers and optical measurement devices, thus eliminating the need for sensing components made of ferromagnetic materials and saving space for their installation and movement. Compared to traditional sensing components, the use of visual markers has a significantly smaller adverse impact on engine performance and avoids loosening or wear caused by displacement or vibration. Since changes in engine operating conditions and vibrations can cause relative positional shifts in the visual markers and optical measurement devices, leading to variations in the image's field of view, determining the pitch angle based on the third marker reduces the adverse effects of these variations and improves the accuracy of the measurement results. Furthermore, the use of optical measurement devices is suitable for obtaining clear images through high-speed photography and for compensation through image enhancement techniques, reducing the adverse effects of high-speed blade rotation, speed changes, and vibrations on the measurement and further improving the accuracy of the results.

[0011] In one or more embodiments of the measuring structure, the first mark is configured as a helix extending circumferentially and axially along the Y-axis, and the second mark is configured as a loop extending circumferentially along the Y-axis.

[0012] In one or more embodiments of the measuring structure, the first mark and the second mark are disposed on the blade or a structure that rotates synchronously with the blade relative to the hub; the third mark is disposed on the hub or a structure that is relatively fixed to the hub.

[0013] In one or more embodiments of the measuring structure, the pitch angle measuring structure includes a pitch angle adjustment device, the pitch angle adjustment device including a first connecting part, the first connecting part being connected to the blade shank, and the first connecting part being rotated to adjust the pitch angle of the blade, and a first mark and a second mark being disposed on the outer surface of the first connecting part.

[0014] In one or more embodiments of the measurement structure, the hub and the plurality of blades are capable of rotating synchronously, with the rotation axis being the X-axis; the optical measurement device includes an image acquisition unit for acquiring images; wherein, a plurality of the image acquisition units are relatively fixed to the X-axis, so that a single image acquisition unit can measure the pitch angle of the plurality of blades.

[0015] In one or more embodiments of the measurement structure, a plurality of the image acquisition units are disposed on the hub corresponding to at least a portion of the blades.

[0016] In one or more embodiments of the measurement structure, a space is defined between the petiole of the blade and the image acquisition unit; wherein the end face of the hub extends inside the space, and the end face of the hub is provided with a measurement hole at a position corresponding to the visual mark, and the image acquisition unit acquires an image of the visual mark through the measurement hole.

[0017] In one or more embodiments of the measurement structure, the end face of the hub extends outside the space, and the image acquisition unit directly acquires images of the visual marker.

[0018] In one or more embodiments of the measuring structure, a plurality of measuring holes are evenly distributed on the end face of the hub.

[0019] In one or more embodiments of the measuring structure, the diameter of the measuring hole satisfies the following relationship:

[0020] ;

[0021] In the formula, The diameter of the measuring hole, The distance between the center of the measuring hole and the image acquisition unit. The angle between the end face of the hub and the X-axis is given. The distance between the visual marker and the image acquisition unit. This is the maximum distance between the first intersection point and the second intersection point.

[0022] According to the method for measuring the pitch angle of a blade according to the second aspect of this application, the pitch angle of the blade is measured using the pitch angle measuring structure as described in the first aspect; the pitch angle measuring method includes the following steps:

[0023] S1. Acquire an image of the pattern;

[0024] S2. Obtain the distance between the first intersection point and the second intersection point in the pattern;

[0025] S3. The blade pitch angle is obtained based on the distance between the first intersection point and the second intersection point.

[0026] In one or more embodiments of the measurement method, step S1 includes:

[0027] The frame rate of the image acquisition is controlled to match the rotational speed of the wheel hub around the X-axis, satisfying the following relationship:

[0028] ;

[0029] In the formula, To capture the frame rate of the image, The number of the blades being measured. The rotational speed of the hub.

[0030] In one or more embodiments of the measurement method, step S2 includes:

[0031] The image is processed using at least one of grayscale conversion, Gaussian blurring, and Canny edge detection. The Hough transform is used to detect line segments in the image. The first marker, the second marker, and the third marker are identified based on the slope of the line segments. The first intersection point and the second intersection point are determined, and the distance between the first intersection point and the second intersection point is obtained.

[0032] In one or more embodiments of the measurement method, step S2 includes:

[0033] The image is processed using artificial intelligence technology to obtain the distance between the first intersection point and the second intersection point.

[0034] In one or more embodiments of the measurement method, the pitch angle measuring structure is configured such that: the first marker is an equidistant helix extending circumferentially and axially along the Y-axis, and the second marker is a ring line extending only circumferentially along the Y-axis; the blade pitch angle has an adjustment range. The blade's pitch angle is... The distance between the corresponding first intersection point and the second intersection point is The blade's pitch angle is The distance between the first intersection point and the second intersection point is Furthermore, step S3 includes:

[0035] Based on the distance between the first intersection point and the second intersection point in any of the patterns The corresponding blade pitch angle was calculated. The following relation is satisfied:

[0036] .

[0037] The aircraft engine according to the third aspect of this application includes a pitch angle measuring structure as described in the first aspect. Attached Figure Description

[0038] The above and other features, properties, and advantages of this application will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, in which the same reference numerals always denote the same features. It should be noted that these drawings are merely illustrative and are not drawn to scale, and should not be construed as limiting the scope of protection actually claimed by this application, wherein:

[0039] Figure 1 This is a partial structural schematic diagram of an aircraft engine according to one embodiment.

[0040] Figure 2 This is a partial structural diagram of a blade according to one embodiment.

[0041] Figure 3 This is a schematic diagram of the structure of a wheel hub according to one embodiment.

[0042] Figure 4 This is a schematic diagram of a pitch angle measurement structure according to one embodiment.

[0043] Figure 5 This is a schematic diagram of the structure of a visual marker according to one embodiment.

[0044] Figure 6 This is a schematic diagram of the blade pitch angle and the corresponding visual marking pattern of one embodiment.

[0045] Figure 7 This is a partial structural diagram of an aircraft engine according to another embodiment.

[0046] Figure 8 This is a partial structural diagram of the blade according to another embodiment.

[0047] Figure 9 This is a partial structural schematic diagram of an aircraft engine according to another embodiment.

[0048] Figure 10 This is a schematic flowchart of a blade pitch angle measurement method according to one embodiment.

[0049] Figure label:

[0050] 1. Aircraft engine;

[0051] 2. Pitch angle adjustment device; 21. First connecting part; 211. First mark; 212. Second mark;

[0052] 3. Leaf blade; 31. Petiole;

[0053] 4. Hub; 41. End face of hub; 411. Measuring hole; 412. Third mark; 42. Second connecting part;

[0054] 5. Image acquisition unit;

[0055] 6. Installation structure;

[0056] 7. Image Processing Unit. Detailed Implementation

[0057] Reference will now be made in detail to various embodiments of this application, examples of which are shown in the accompanying drawings and described below. Although this application will be described in conjunction with exemplary embodiments, it should be understood that this application is not intended to be limited to those exemplary embodiments. Rather, this application is intended to cover not only these exemplary embodiments, but also various alternatives, modifications, equivalents, and other embodiments that may be included within the spirit and scope of this application as defined by the appended claims.

[0058] This application uses specific terms to describe embodiments of the application. For example, "an embodiment" and / or "one embodiment" refers to a feature, structure, or characteristic associated with at least one embodiment of the application. Therefore, it should be emphasized and noted that "an embodiment" or "one embodiment" mentioned twice or more in different locations in this application does not necessarily refer to the same embodiment. Furthermore, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined. In the following description, the orientation or positional relationship indicated by terms such as "upper," "lower," "inner," "outer," "front," "rear," or other directional terms is based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing the application and simplifying the description, and does not indicate or imply that the device or component referred to must have a specific orientation, be constructed and / or implemented in a specific orientation, and therefore should not be construed as a limitation of the application. In this application, the terms "first," "second," etc., are only used for distinguishing descriptions and should not be construed as indicating or implying positional relationships or order of importance. In the following description, unless otherwise expressly specified or limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly; for example, they can refer to fixed connections or movable connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0059] This application uses flowcharts to illustrate the operations performed according to embodiments of this application. It should be understood that, depending on the actual situation, the steps shown in the diagrams are not necessarily performed sequentially, and other operations may be added to these processes, or one or more steps may be removed from these processes.

[0060] It is understood that the pitch angle measurement structure and method provided in this application are applicable to measuring the pitch angle of the fan blades of aero engines. They can also be applied to other applicable occasions, as long as the blades that require a measuring device are used and the pitch angle measurement structure disclosed in the embodiments of this application can be applied. They are not limited thereto.

[0061] See Figure 1 , Figure 7 , Figure 9 The illustrated aero-engine 1 is generally symmetrical about the X-axis; a plurality of blades 3 extend radially from a hub 4 along the X-axis and are connected to the hub 4 via blade shanks 31; the blades 3 are rotatably connected to the hub 4 to achieve pitch angle adjustment, and the axis of rotation is the Y-axis extending radially along the X-axis. Specifically, in some embodiments, the pitch angle adjustment device 2 includes a first connecting portion 21 (e.g., a rocker arm), which connects to the blade shank 31 and is rotatable to drive changes in the pitch angle of the blades 3; the hub 4 includes a second connecting portion 42, to which the blade shank 31 is inserted via bearings or bushings, thereby being supported by the hub 4. In some embodiments, the hub 4 and the blades 3 are also rotatable about the X-axis, i.e., configured as rotor blades.

[0062] See Figures 1 to 9 The pitch angle measurement structure shown includes visual markers and an optical measuring device. The visual markers include a first marker 211 and a second marker 212 extending circumferentially along the Y-axis; and a third marker 412 extending axially along the Y-axis. The first marker 211, the second marker 212, and the third marker 412 form a pattern. In the pattern, the extension direction of the third marker 412 (the extension line of the third marker 412) intersects the first marker 211 at a first intersection point b and the second marker 212 at a second intersection point c. The distance between the first intersection point b and the second intersection point c changes synchronously with the pitch angle of the blade 3. The optical measuring device is configured to acquire an image of the pattern of the visual markers to determine the pitch angle of the blade 3 based on the distance between the first intersection point b and the second intersection point c in the pattern.

[0063] The pitch angle measurement structure described above replaces the traditional electromagnetic measurement structure with a pitch angle measurement structure composed of visual markers and optical measuring devices. This eliminates the need for sensing components made of ferromagnetic materials, saving space for the installation and movement of sensing components. Compared to the sensing components of traditional solutions, visual markers have a significantly smaller adverse impact on engine performance and avoid problems such as loosening or wear caused by displacement or vibration. Since changes in engine operating conditions and vibrations may cause relative positional shifts between the visual markers and the optical measuring devices, resulting in changes in the field of view of the image, determining the pitch angle based on the third marker 412 can reduce the adverse effects of changes in the field of view and improve the accuracy of the measurement results. The use of optical measuring devices is also suitable for obtaining clear images through high-speed imaging and for compensation through image enhancement technology, reducing the adverse effects of high-speed rotation, speed changes, and vibration of the blades 3 on the measurement and improving the accuracy of the measurement results.

[0064] Specifically, visual markings refer to markings that can be sensed by optical measuring devices. They can be formed by applying paint or engraving. Generally, visual markings can be configured to be clearly visible during typical engine overhaul intervals without falling off, wearing, or corroding, in order to ensure the reliability and service life of the measuring structure. The aforementioned extension of the first mark 211 and the second mark 212 along the Y-axis in a circumferential direction means that the extension direction of the first mark 211 and the second mark 212 has at least a circumferential component along the Y-axis; the extension of the third mark 412 along the Y-axis in an axial direction means that the extension direction of the third mark 412 has at least an axial component along the Y-axis; and, in order to ensure that the distance between the first intersection point b and the second intersection point c in the pattern can change synchronously with the pitch angle of the blade 3, at least one of the first mark 211 and the second mark 212 also has an axial extension component along the Y-axis; in some embodiments, the first mark 211 and the second mark 212 are configured such that the distance between the first intersection point b and the second intersection point c has a one-to-one correspondence with the pitch angle of the blade 3, that is, there is no situation where the same distance between the first and second intersection points corresponds to multiple pitch angles, thus avoiding mismeasurement; for example, the first mark 211 gradually approaches or moves away from the second mark 212, so that the distance between the first and second intersection points changes monotonically. For example Figures 2 to 6 As shown, the first mark 211 can be a helix relatively fixed to the blade 3 and extending circumferentially and axially along the Y-axis; the second mark 212 can be a ring-shaped line relatively fixed to the blade 3 and extending only circumferentially around the Y-axis; and the third mark 412 can be a straight line extending along the Y-axis (radial of the hub 4) on the hub 4. Thus, when the pitch angle of the blade 3 changes, the first mark 211 and the second mark 212 move relative to the third mark 412, causing the pattern to change accordingly, such as... Figure 6As shown; the visual markers can also be configured in other structures, for example, the first marker 211 and the second marker 212 can also be helices with unequal pitches, and are not limited thereto. It can be understood that the above-described pitch angle measurement structure is particularly suitable for arranging the visual markers and optical measuring devices approximately along the X-axis direction. The visual markers and optical measuring devices can also be arranged in other orientations, for example, the visual markers and optical measuring devices can be arranged approximately along the Y-axis direction, as long as the pattern of the visual markers and the image acquisition unit are arranged facing each other, and are not limited thereto.

[0065] like Figure 1 , Figure 7 , Figure 9 As shown, the optical measurement device may include an image acquisition unit 5 and an image processing unit 7; the image acquisition unit 5 is used to acquire an image of a pattern, which is arranged facing the visual markers, and its field of view covers at least a portion of the pattern formed by the first marker 211, the second marker 212, and the third marker 412; generally, the image acquisition unit 5 may be configured as a high-speed camera; the image acquisition unit 5 and the image processing unit 7 are connected by wired or wireless means to transmit images; the image processing unit 7 is used to receive an image of the pattern from the image acquisition unit 5 and determine the pitch angle of the blade 3 based on the distance between the first intersection point b and the second intersection point c in the pattern; generally, the image processing unit 7 may include a processor and a memory; the memory is used to store instructions executable by the processor, and the processor is used to execute the instructions to implement the steps of the method of obtaining the pitch angle of the blade 3 based on the received image. In some embodiments, the image processing unit 7 may also include a communication device for transmitting the measurement result of the pitch angle to the engine monitoring and control system, but this is not a limitation.

[0066] The image acquisition unit 5, image processing unit 7, memory, and processor described above are not limited to any specific image acquisition unit 5, image processing unit 7, memory, or processor. For example, in some cases, at least one of the image acquisition unit 5, image processing unit 7, memory, and processor may have a distributed structure. For instance, it may include a memory and processor located at the sensing device end and the back-end cloud, jointly realizing the measurement of the propeller pitch angle. Furthermore, in embodiments employing a distributed structure, the specific execution terminal for each step can be adjusted according to actual conditions, and the specific implementation scheme of each step at a specific terminal should not limit the scope of protection of this invention.

[0067] In some embodiments, the image acquisition unit 5 is configured to adjust the acquisition of images; for example, in some embodiments, the blade 3 is a rotor blade that can rotate about the X-axis, and the image acquisition unit 5 is set relatively fixed to the X-axis and does not rotate with the blade 3. By adjusting the frame rate of image acquisition to match the rotation speed of the rotor blade, images corresponding to several visual markers are accurately acquired, and the exposure time of image acquisition is adjusted to ensure image clarity, etc., but not limited thereto.

[0068] See Figure 2 , Figure 3 , Figure 8 As shown, in one or more embodiments, the first mark 211 and the second mark 212 are disposed on the blade 3 or in a structure that rotates synchronously with the blade 3 relative to the hub 4 about the Y-axis; the third mark 412 is disposed on the hub 4 or in a structure that is relatively fixed to the hub 4, that is, the third mark 412 is disposed in a structure that does not rotate with the blade 3 about the Y-axis. For example, the pitch angle measuring structure may also include a pitch angle adjusting device 2, which includes a first connecting part 21 (e.g., a rocker arm), the first connecting part 21 being connected to the blade shank 31 and rotatable, thereby realizing the pitch angle adjustment of the blade 3, and the first mark 211 and the second mark 212 being disposed on the outer surface of the first connecting part 21, such as Figure 2 As shown; the hub 4 may further include a hub end face 41 and a second connecting portion 42, with the blade shank 31 inserted into the second connecting portion 42, and the hub end face 41 providing support for the blade 3 and the second connecting portion 42; wherein, a third mark 412 may be provided on the hub end face 41, such as Figure 3 As shown; it can also be set in the second connecting part 42, such as Figure 8 As shown; thus, the form of visual markings can be flexibly selected according to the internal structure of the engine.

[0069] In some embodiments, the first mark 211 is configured as a helix extending circumferentially and axially along the Y-axis, such as an equidistant helix; the second mark 212 is configured as a loop around the Y-axis in the circumferential direction; thus, the first mark 211 and the second mark 212 can be distinguished and identified according to the slope of each line segment in the image, and it is beneficial to establish the relationship between the distance between the first intersection point b and the second intersection point c and the blade pitch angle to simplify the calculation.

[0070] like Figure 1 , Figure 7As shown, in one or more embodiments, the blades 3 are configured as rotor blades, and the hub 4 and several blades 3 can rotate synchronously about the X-axis. The optical measurement device also includes a mounting structure 6 for the image acquisition unit 5. The mounting structure 6 is fixed relative to the X-axis, so that the image acquisition unit 5 does not rotate with the hub 4 and the blades 3. Thus, when multiple blades 3 rotate, they can pass through positions facing the same image acquisition unit 5, so that a single image acquisition unit 5 can measure the pitch angle of multiple blades 3, such as measuring all blades 3. This helps to reduce the number of image acquisition units 5, saving space and cost. It should be noted that the number of image acquisition units 5 is not limited to one. Using multiple image acquisition units 5 helps to improve the accuracy and reliability of the measurement.

[0071] like Figure 9 As shown, in one or more embodiments, a plurality of image acquisition units 5 are disposed on a hub 4 corresponding to at least a portion of the blades 3. The hub 4 provides mounting positions for the blades 3 and correspondingly provides mounting positions for the image acquisition units 5. Generally, the plurality of image acquisition units 5 can be evenly distributed on the hub 4 to prevent dynamic imbalance problems.

[0072] like Figure 1 , Figure 7 , Figure 9 As shown, a space is defined between the petiole 31 and the image acquisition unit 5. In some embodiments, such as Figure 1 As shown, the end face 41 of the hub extends inside the space between the blade stalk 31 and the image acquisition unit 5. A light-transmitting measuring hole 411 is provided on the end face 41 of the hub corresponding to the position of the visual mark, through which the image acquisition unit 5 acquires an image of the visual mark. In other embodiments, the end face 41 of the hub does not extend outside the space between the visual mark and the image acquisition unit 5, so that the hub 4 does not obstruct the field of view of the image acquisition unit 5, and the image acquisition unit 5 can directly acquire an image of the visual mark without the need for a measuring hole; for example... Figure 7 As shown, the end face 41 of the hub extends on one side of the blade stalk 31 along the X-axis (e.g., the front side of the engine), and the image acquisition unit 5 is fixed on the other side along the X-axis (e.g., the rear side of the engine); or as... Figure 9 As shown, the image acquisition unit 5 can also be fixed on the end face 41 of the hub.

[0073] like Figure 3 As shown, in one or more embodiments, a plurality of measuring holes 411, such as two or three, are evenly distributed on the end face 41 of the hub. This facilitates the measurement of the pitch angle of the plurality of blades 3 to ensure that the measurement results are accurate and reliable, and enables the monitoring of the working status of the plurality of blades 3, and makes the mass distribution uniform to prevent dynamic imbalance problems.

[0074] like Figure 4 As shown, in one or more embodiments, the diameter of the measuring hole 411 satisfies the following relationship:

[0075] ;

[0076] In the formula, To measure the diameter of hole 411, To measure the distance between the center of the aperture 411 and the image acquisition unit 5, The angle between the end face 41 of the hub and the X-axis is [angle]. The distance between the visual marker and the image acquisition unit 5. This is the maximum distance between the first intersection point b and the second intersection point c.

[0077] By limiting the minimum size of the measuring aperture 411, it is ensured that the field of view of the optical acquisition unit through the measuring aperture 411 can effectively cover the pattern with the largest distance between the first intersection point b and the second intersection point c, thus avoiding measurement dead zones that occur within the pitch angle adjustment range.

[0078] See Figure 10 The pitch angle measurement method for blade 3 shown above uses the above-described pitch angle measurement structure to measure the pitch angle of blade 3; the pitch angle measurement method includes the following steps:

[0079] S1. Acquire the image of the pattern;

[0080] S2. Obtain the distance between the first intersection point b and the second intersection point c in the pattern;

[0081] S3. Based on the distance between the first intersection point b and the second intersection point c, the pitch angle of blade 3 is obtained.

[0082] In one or more embodiments, step S1 specifically includes:

[0083] The image acquisition unit 5 obtains the rotor blade speed information from the engine's monitoring and control system, and automatically controls the image acquisition frame rate accordingly, ensuring that the acquisition frame rate matches the rotor speed. This guarantees that each acquired image frame corresponds to a visual marker detection result, reducing unnecessary image acquisition, improving image data processing efficiency, and controlling the acquisition frame rate to satisfy the following relationship:

[0084] ;

[0085] In the formula, The frame rate for capturing images, The number of leaflets 3 being measured. This refers to the rotational speed of hub 4.

[0086] like Figure 5 , Figure 6As shown, in one or more embodiments, step S2 specifically includes:

[0087] The image is preprocessed using at least one of grayscale conversion, Gaussian blurring, and Canny edge detection. Then, Hough transform is used to detect line segments in the image, and the first marker 211, the second marker 212, and the third marker 412 are identified based on the slope of the line segments. The third marker 412 intersects the contour line of the measuring hole 411 at points a and d. The line segment direction of the third marker 412 intersects the first marker 211 and the second marker 212 at first intersection point b and second intersection point c, respectively. The distance between the first intersection point b and the second intersection point c is calculated. This method helps reduce computational load and noise interference. Step S2 can also use other methods to obtain the distance between the first intersection point b and the second intersection point c. For example, artificial intelligence technology can be used to process the image. By collecting image data in complex and diverse operating scenarios, the artificial intelligence model can be trained and optimized based on the image data to achieve accurate recognition of visual markers, and the distance between the two intersection points can be calculated based on the recognition results. This method is not limited to this approach.

[0088] like Figure 6 As shown, in one or more embodiments, step S3 specifically includes:

[0089] Prior to, within the pitch angle adjustment range, obtain corresponding multiple pitch angles. The distance between the first intersection point b and the second intersection point c This establishes a complete distance between the first intersection point b and the second intersection point c within the pitch angle adjustment range. Pitch angle with blade 3 The correspondence between them.

[0090] Specifically, the pitch angle measuring structure can also be configured such that the pitch angle of blade 3 has an adjustable range. The first mark 211 is an equidistant spiral extending circumferentially and axially along the Y-axis, and the second mark 212 is a loop extending only circumferentially along the Y-axis, thus the distance between the first intersection point b and the second intersection point c. With blade 3 pitch angle A linear relationship is formed between them, requiring only two critical values ​​of the pitch angle adjustment range to be set in advance. The corresponding image can be calibrated; the pitch angle of blade 3 is... The distance between the corresponding first intersection point b and the second intersection point c is The pitch angle of blade 3 is The distance between the first intersection point b and the second intersection point c is Based on the distance between the first intersection point b and the second intersection point c in any of the collected patterns. It can calculate the corresponding blade 3 pitch angle. The following relation is satisfied:

[0091] .

[0092] In some embodiments, the measurement method further includes transmitting the measured blade pitch angle information to the engine's monitoring and control system, but is not limited thereto.

[0093] like Figure 1 , Figure 7 , Figure 9 The aircraft engine 1 shown includes the above-mentioned pitch angle measuring structure for measuring the pitch angle of the fan blades of the aircraft engine 1.

[0094] The following example illustrates this application using a propeller pitch angle measurement structure and method applied to the measurement of fan blades in an aero-engine 1, but it is not limited thereto; Figure 1 As shown, the image acquisition unit 5 is equipped with one or more high-speed cameras and is mounted on the mounting structure 6. The mounting structure 6 is fixed relative to the X-axis and does not rotate around the X-axis with the hub 4 and the fan blade 3. The end face 41 of the hub is located between the high-speed camera and the blade stalk 31, and the end face 41 of the hub is provided with three measuring holes 411 to avoid obstructing the field of view of the high-speed camera.

[0095] X-axis distance between high-speed camera and visual marker The distance between the center of the measuring hole 411 and the X-axis of the high-speed camera is 300mm. The maximum Y-axis distance between the first mark 211 and the second mark 212 is 150mm. The angle between the end face 41 of the wheel hub and the X-axis is 100mm. If the angle is 45°, then the diameter of measuring hole 411 is... Satisfying the relation:

[0096]

[0097] Image acquisition frame rate Automatic control is implemented to match the rotational speed of the rotor blades. Ensure that each captured image corresponds to a visually marked pattern, satisfying the following relationship:

[0098]

[0099] For example, when the rotation speed is 25 r / s, the corresponding acquisition frame rate is 75 f / s.

[0100] The adjustment range of the blade's 3-pitch angle is configured as follows: Maximum pitch angle for Distance between the two intersection points of the corresponding patterns for Minimum pitch angle for Distance between the two intersection points of the corresponding patterns for The first mark 211 and the second mark 212 are respectively configured as equidistant spirals and circular lines; the high-speed camera acquires an image of any pattern within the adjustment range, and the distance between the first intersection point b and the second intersection point c is obtained through image processing. According to distance The blade pitch angle corresponding to the image acquisition time was calculated. The following relation is satisfied:

[0101]

[0102] For example, based on the image at a certain moment, the distance between the first intersection point b and the second intersection point c is... Then the blade pitch angle of blade 3 at that moment can be obtained as:

[0103] .

[0104] In summary, the beneficial technical effects of this application include, but are not limited to, at least one of the following:

[0105] A pitch angle measurement structure composed of visual markers and optical measuring devices replaces the traditional electromagnetic measurement structure, eliminating the need for sensing components made of ferromagnetic materials and saving space for their installation and movement. Compared to traditional sensing components, visual markers have significantly less adverse impact on engine performance and avoid loosening or wear caused by displacement or vibration. Since changes in engine operating conditions and vibrations can cause relative positional shifts between the visual markers and optical measuring devices, resulting in variations in the field of view, determining the pitch angle based on a third marker reduces the adverse effects of these field-of-view variations, improving the accuracy of the measurement results. Furthermore, the use of optical measuring devices is suitable for obtaining clear images through high-speed photography and for compensation through image enhancement techniques, reducing the adverse effects of high-speed blade rotation, speed changes, and vibrations on the measurement, further improving the accuracy of the results.

[0106] While this application discloses preferred embodiments as described above, it is not intended to limit the scope of this application. Any changes and modifications can be made by those skilled in the art without departing from the spirit and scope of this application. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application, without departing from the content of the technical solution of this application, fall within the protection scope defined by the claims of this application.

Claims

1. A structure for measuring the pitch angle of blades, characterized in that, The blade is rotatably connected to the hub, with the rotation axis being the Y-axis; the pitch angle measurement structure includes visual markers and an optical measurement device; wherein... The visual markers include: The first and second marks extend circumferentially along the Y-axis; The third mark extends axially along the Y-axis; and, The first mark, the second mark, and the third mark form a pattern; in the pattern, the extending direction of the third mark intersects the first mark at a first intersection point and the second mark at a second intersection point; the distance between the first intersection point and the second intersection point changes synchronously with the blade pitch angle; The optical measuring device is configured to acquire an image of the pattern in order to determine the blade pitch angle based on the distance between the first intersection point and the second intersection point in the pattern.

2. The measuring structure according to claim 1, characterized in that, The first mark is configured as a spiral extending circumferentially and axially along the Y-axis, and the second mark is configured as a loop extending circumferentially along the Y-axis.

3. The measuring structure according to claim 1, characterized in that, The first mark and the second mark are disposed on the blade or a structure that rotates synchronously with the blade relative to the hub; the third mark is disposed on the hub or a structure that is fixed relative to the hub.

4. The measuring structure according to claim 1, characterized in that, The pitch angle measuring structure includes a pitch angle adjustment device, which includes a first connecting part connected to the blade shank, and the first connecting part rotates to adjust the pitch angle of the blade. The first mark and the second mark are disposed on the outer surface of the first connecting part.

5. The measuring structure according to claim 1, characterized in that, The hub and the plurality of blades are capable of rotating synchronously, with the rotation axis being the X-axis; the optical measuring device includes an image acquisition unit for acquiring images; wherein, A plurality of the image acquisition units are fixed relative to the X-axis, such that a single image acquisition unit can measure the pitch angle of a plurality of the blades; or, a plurality of the image acquisition units are disposed on the hub corresponding to at least a portion of the blades.

6. The measuring structure according to claim 1, characterized in that, The optical measuring device includes an image acquisition unit for acquiring images, and a space is defined between the petiole of the blade and the image acquisition unit; wherein, The end face of the hub extends inside the space, and the end face of the hub is provided with a measuring hole at a position corresponding to the visual mark, through which the image acquisition unit acquires an image of the visual mark; or, the end face of the hub extends outside the space, and the image acquisition unit directly acquires an image of the visual mark.

7. The measuring structure according to claim 6, characterized in that, A plurality of measuring holes are evenly distributed on the end face of the hub; and / or, the diameters of the measuring holes satisfy the following relationship: ； In the formula, The diameter of the measuring hole, The distance between the center of the measuring hole and the image acquisition unit. The angle between the end face of the hub and the X-axis is given. The distance between the visual marker and the image acquisition unit. This is the maximum distance between the first intersection point and the second intersection point.

8. A method for measuring the pitch angle of blades, characterized in that, The pitch angle of the blade is measured using the pitch angle measuring structure as described in any one of claims 1 to 7; the pitch angle measurement method includes the following steps: S1. Acquire an image of the pattern; S2. Obtain the distance between the first intersection point and the second intersection point in the pattern; S3. The blade pitch angle is obtained based on the distance between the first intersection point and the second intersection point.

9. The measurement method according to claim 8, characterized in that, The pitch angle measurement method further includes: Step S1 includes: The frame rate of the image acquisition is controlled to match the rotational speed of the blade around the X-axis, satisfying the following relationship: ； In the formula, To capture the frame rate of the image, The number of the blades being measured. The rotational speed of the blade; And / or, Step S2 includes: The image is processed using at least one of grayscale conversion, Gaussian blur, and Canny edge detection. Hough transform is used to detect line segments in the image. The first marker, the second marker, and the third marker are identified based on the slope of the line segments. The first intersection point and the second intersection point are determined, and the distance between the first intersection point and the second intersection point is obtained. Alternatively, artificial intelligence technology is used to process the image to obtain the distance between the first intersection point and the second intersection point. And / or, The pitch angle measuring structure is configured such that: the first marker is an equidistant helix extending circumferentially and axially along the Y-axis, and the second marker is a ring line extending circumferentially along the Y-axis; the blade pitch angle has an adjustable range. The blade's pitch angle is... The distance between the corresponding first intersection point and the second intersection point is The blade's pitch angle is The distance between the first intersection point and the second intersection point is Furthermore, step S3 includes: Based on the distance between the first intersection point and the second intersection point in any of the patterns The corresponding blade pitch angle was calculated. The following relation is satisfied: 。 10. An aircraft engine, characterized in that, Includes the pitch angle measuring structure as described in any one of claims 1 to 7.

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