A coaxiality measurement and leveling method for a four-tilt-rotor aircraft transmission system

Abstract

The application discloses a kind of four tilting rotor aircraft transmission system coaxiality measurement and leveling method, it is related to the field of aircraft transmission system assembly.The present application measures the radial offset of the shaft body at both ends of transmission shaft diaphragm coupling by contact probe;According to the law of similar triangles, the radial offset is converted into the angular deviation of the transmission shaft;According to the comparison result of the angular deviation and the preset threshold value, it is determined whether to implement gasket leveling on the transmission shaft;Measure and level are sequentially completed for multiple transmission shafts in the preset decoupling order until the angular deviation of all transmission shafts meets the preset requirements.The method of the present application is independent of the dependence on unobstructed light path, can achieve high-precision measurement in limited small space through simple tooling, and can guide leveling through theoretical calculation.

Description

Technical Field

[0001] This invention relates to the field of aircraft transmission system assembly, and more specifically to a method for measuring and leveling the coaxiality of a four-tilt rotor aircraft transmission system. Background Technology

[0002] The quad tiltrotor aircraft combines the vertical takeoff and landing capabilities of a helicopter with the high-speed cruise and long-range capabilities of a fixed-wing aircraft. Its functionality relies on a complex power transmission system. For the integrated powertrain configuration, where the engine's power is transmitted to the four rotor shafts via wing driveshafts, the transmitted power is substantial. Furthermore, there is a certain angular misalignment between the connected wing driveshaft axes, and the entire transmission system needs to adapt to the deformation of the wing under various flight conditions. Given the characteristics of the quad tiltrotor aircraft's integrated transmission system—long transmission links, high power transmission, and high installation precision requirements—the leveling of the entire transmission system requires controlling the angular deviation of all shafts at the diaphragm couplings within allowable limits to meet the vibration, reliability, and lifespan requirements of subsequent transmission system operation.

[0003] Currently, common methods for leveling drive shafts in the aviation field include optical collimation and laser alignment. Traditional methods are technologically mature, but their testing requires a clear optical path and sufficient space around the shaft for operators or large measuring fixtures. However, for aircraft configurations with integrated powertrains and fuselages, the drive shafts are obscured by structural frames and stringers, making it impossible to directly observe the couplings and establish an optical reference. Furthermore, there is insufficient space to extend measuring tools around the shafts for observation. Therefore, traditional leveling methods cannot be used to level the drive shafts.

[0004] Therefore, how to solve the problem of directly testing the coaxiality of the transmission system of a quad tiltrotor aircraft with integrated power and fuselage still requires further research by those skilled in the art. Summary of the Invention

[0005] In view of this, this invention proposes a method for testing and leveling the angular deviation of the drive shaft indirectly by measuring the offset of a test probe and combining it with the principle of geometric similarity. This method is independent of the need for a clear optical path, enabling high-precision measurements within a limited space using simple tooling, and can guide leveling through theoretical calculations. The method proposed in this invention has been successfully applied to the leveling of the drive shaft system of a four-tilt rotor aircraft, demonstrating high engineering application value.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for measuring and leveling the coaxiality of a four-tilt rotor aircraft transmission system includes the following steps: The radial offset of the shafts at both ends of the diaphragm coupling of the drive shaft was measured using a contact probe. Based on the law of similar triangles, the radial offset is converted into the angular deviation of the drive shaft; Based on the comparison between the angular deviation and the preset threshold value, determine whether to perform shim leveling on the drive shaft; The multiple drive shafts are measured and leveled sequentially according to the preset decoupling sequence until the angular deviation of all drive shafts meets the preset requirements.

[0007] Optionally, brackets are installed at the input and output ends of the diaphragm coupling, and the dial indicator probe is fixed to either bracket and made perpendicular to the shaft surface. The two shafts are rotated synchronously, and the dial indicator variation of the probe at multiple rotation angles is collected. The measurement error is calculated first and the installation validity is verified. Then, the dial indicator variation at key angles is extracted to calculate the radial offset.

[0008] Optionally, the formula for calculating the radial offset is as follows: ; in, These represent the percentage changes in the dial gauge readings of the probe when it rotates to 0°, 90°, 180°, 270°, 360°, 450°, 540°, and 630°, respectively.

[0009] Optionally, the radial offset includes a vertical offset X and a horizontal offset Y, calculated using the following formula: ; ; in, This represents the change in the dial gauge value of the probe when it rotates 0°. This represents the change in the dial gauge reading of the probe when it rotates 90°. This represents the change in the dial gauge reading of the probe when it rotates 180°. This represents the percentage change in the dial gauge of the probe when it rotates 270°.

[0010] Optionally, the calculation of the angular deviation includes: According to the law of similar triangles, the angular deviation between the vertical and horizontal directions is calculated as follows: ; ; in, To fix the radius at the dial gauge. The offset in the vertical direction is measured using a dial indicator. The horizontal offset is measured using a dial indicator. and These represent the vertical and horizontal angular deviations at the center of the drive shaft diaphragm coupling assembly, and the axial angular deviations, respectively. It consists of two angular deviation components located in two mutually perpendicular planes: ; in, Indicates the angular deviation in the vertical direction. This indicates the angular deviation in the horizontal direction. The angular deviation of the drive shaft must meet the following requirements. ; in, The acceptable angular deviation threshold value for drive shaft leveling is set based on the model and experience.

[0011] Optionally, the shim leveling includes: determining the main leveling direction based on the magnitude of the angular deviation component, determining the specific offset direction of the shaft by combining the positive and negative probe readings, selecting the corresponding shim installation position and calculating the shim thickness, adding the shim according to the calculated thickness, and then re-measuring the angular deviation until it is qualified.

[0012] Optional, for the thickness of the added shim The calculation is based on the law of similar triangles and the position of the shim. The specific calculation formula is as follows: ; ; in, and These represent the thickness of the shims added in the vertical and horizontal directions, respectively. and The angular deviation is perpendicular to the horizontal direction. and These represent the distances between the shim locations and the axis in the vertical and horizontal directions, respectively, for the wing drive shaft system. This refers to the distance between the wing-fuselage junction and the wing axis, for the fuselage and engine drive shaft system. These are the distances between shim positions 1, 2, and 3 and the engine drive shaft and the transmission shaft, respectively.

[0013] Optionally, after leveling, record the dial gauge momentum value after the probe rotates one revolution, and calculate the angular deviation value of the drive shaft after adding shims. , ; in, and The offsets in the vertical and horizontal directions were measured using a dial indicator, respectively. To fix the radius at the dial indicator, determine the adjustment... Does it meet the requirements? If the requirements are not met, repeat the leveling process until the angular deviation meets the requirements.

[0014] As can be seen from the above technical solution, compared with the prior art, the present invention provides a method for measuring and leveling the coaxiality of a four-tilt rotor aircraft transmission system, which has the following beneficial effects: (1) The angular deviation of the transmission shaft, which cannot be directly measured, can be converted into the circumferential offset of the probe tip, which can be directly measured and is not limited by the line of sight. This solves the problems of line of sight obstruction and limited space faced by the traditional leveling measurement method in the four-tilt configuration of the interconnected transmission system with the power body integrated.

[0015] (2) This invention proposes a complex shaft leveling and decoupling strategy for the complex coupling relationship of the seven drive shafts in the transmission system of a four-tilt rotor aircraft. Targeted leveling strategies are proposed for the wing drive shaft system, fuselage drive shaft system, and power drive shaft respectively. The leveling rules greatly reduce the debugging difficulty of the multi-axis coupled system.

[0016] (3) Compared with the large laser alignment instrument and other tooling in traditional leveling test methods, the measuring tooling designed in this invention occupies less space, is easy to install, can be deeply inserted into the compact body for in-situ measurement, does not require disassembling a large number of body structures, greatly improves the overall assembly efficiency of the transmission system, and has high engineering application value. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0018] Figure 1 This is a flowchart of the test and leveling process for the transmission system of a four-tilt rotor aircraft, as proposed in this patent. Figure 2 A schematic diagram of the interconnected integrated transmission system for a four-tilt rotor aircraft; Figure 3 This is a schematic diagram of direct measurement of coaxiality. Figure 4 This is a schematic diagram of the offset in the direction perpendicular to the horizontal in the side view of the drive shaft; Figure 5 This is a schematic diagram of the drive shaft deflection angle; Figure 6 A schematic diagram showing the locations where shims can be added to the fuselage and power shaft system; Figure 7 This is a magnified view of the shim location 1 and a schematic diagram of the shim location. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] This invention discloses a method for measuring and leveling the coaxiality of a transmission system in a four-tilt rotor aircraft, such as... Figure 1 As shown in the figure, i represents the i-th drive shaft (i=1,2,...,7) that needs to be leveled. The leveling sequence is: engine front drive shaft (shaft 1), main reducer rear drive shaft (shaft 2), rear fuselage reducer front drive shaft (shaft 3), left front wing drive shaft (shaft 4), right front wing drive shaft (shaft 5), left rear wing drive shaft (shaft 6), and right rear wing drive shaft (shaft 7). The leveling process includes the following steps: The radial offset of the shafts at both ends of the diaphragm coupling of the drive shaft was measured using a contact probe. Based on the law of similar triangles, the radial offset is converted into the angular deviation of the drive shaft; Based on the comparison between the angular deviation and the preset threshold value, determine whether to perform shim leveling on the drive shaft; The multiple drive shafts are measured and leveled sequentially according to the preset decoupling sequence until the angular deviation of all drive shafts meets the preset requirements.

[0021] The specific steps of this method are as follows: Step 1: Installation and testing of the coaxiality measurement fixture for the transmission system: The drive shaft arrangement of a four-tilt rotor aircraft is as follows: Figure 2 As shown in the diagram, shaft 1 represents the drive shaft behind the main reducer and forward of the fuselage; shaft 2 represents the drive shaft before the rear fuselage reducer and backward of the fuselage; shaft 3 represents the drive shaft behind the main reducer and forward of the engine; shaft 4 represents the drive shaft of the left front wing; shaft 5 represents the drive shaft of the right front wing; shaft 6 represents the drive shaft of the left rear wing; and shaft 7 represents the drive shaft of the right rear wing. A total of seven drive shafts need to be leveled, including: the power drive shaft: forward of the engine (shaft 1); the fuselage drive shaft system: the drive shaft behind the main reducer (shaft 2) and the drive shaft before the rear fuselage reducer (shaft 3); and the wing drive shaft system: the drive shaft of the left front wing (shaft 4), the drive shaft of the right front wing (shaft 5), the drive shaft of the left rear wing (shaft 6), and the drive shaft of the right rear wing (shaft 7).

[0022] Coaxiality needs to be measured at both ends of each shaft, which can be divided into inner and outer sides (shafts 4-7) and front and rear sides (shafts 1-3) according to the axial direction. Since traditional coaxiality measurement fixtures require a large space and are difficult to install and measure on the configuration of a four-tilt rotor aircraft with an integrated powertrain and transmission system, this embodiment proposes to measure using a bracket and probe method, which requires simple and easy-to-install fixtures.

[0023] Specifically, one bracket is installed at each input and output end of each diaphragm coupling, and a dial indicator probe is fixed on one of the brackets. In the initial position, the probe is kept perpendicular to the axial surface. Figure 3 As shown in the figure, To fix the radius at the dial gauge. The offset measured by the dial gauge. This refers to the angular deviation of the transmission shaft.

[0024] Rotate both axes clockwise twice simultaneously, record the dial indicator momentum values ​​at 90° intervals of probe rotation, and calculate the measurement error. The calculation formula is as follows:

[0025] in, These represent the dial gauge changes of the probe when it rotates 0°, 90°, 180°, 270°, 360°, 450°, 540°, and 630°, respectively. This is used to determine the measurement error. If the value is less than 5%, proceed to the next step; otherwise, readjust the probe installation position until the requirement is met.

[0026] Step 2: Calculation of angular deviation of the transmission shaft: After the coaxiality measuring fixture is installed and fixed, rotate the two shafts clockwise one revolution and record the dial indicator momentum value at every 90° interval of probe rotation. The offset in the vertical direction from the side view of the transmission shaft can be measured. offset in the horizontal direction ,like Figure 4 As shown in the figure, This represents the change in the dial gauge value of the probe when it rotates 0°. This represents the change in the dial gauge reading of the probe when it rotates 90°. This represents the change in the dial gauge reading of the probe when it rotates 180°. This represents the percentage change in the dial gauge of the probe when it rotates 270°.

[0027]

[0028] in, This represents the change in the dial gauge value of the probe when it rotates 0°. This represents the change in the dial gauge reading of the probe when it rotates 90°. This represents the change in the dial gauge reading of the probe when it rotates 180°. Let be the percentage change in the dial gauge of the probe when the probe rotates 270°. According to the law of similar triangles, the angular deviation in the vertical and horizontal directions can be calculated as follows:

[0029] in, To fix the radius at the dial gauge. The offset in the vertical direction is measured using a dial indicator. The horizontal offset is measured using a dial indicator. and These are the vertical and horizontal angular deviations at the center of the drive shaft diaphragm coupling assembly, respectively. Figure 5 As shown in the figure, the ground (absolute) coordinate system is the aircraft body coordinate system X, Y, Z. This coordinate system is used to determine the position of the most important nodes of the transmission system. The X, Y, and Z axes (viewed from back to front in the heading) are defined as follows: X: Longitudinal direction, positive along the longitudinal direction of the aircraft body backward; Y: Lateral direction, positive along the lateral direction of the aircraft body to the right; Z: Vertical direction, positive vertically upward. and These refer to the angular deviations in the vertical and horizontal directions at the center of the diaphragm coupling assembly of the drive shaft, respectively.

[0030] axial deviation It consists of two angular deviation components located in two mutually perpendicular planes:

[0031] in, Indicates the angular deviation in the vertical direction. This indicates the angular deviation in the horizontal direction. The angular deviation of the drive shaft must meet the following requirements.

[0032] in, This is a threshold value for acceptable angular deviation during drive shaft leveling, set based on model and experience. The initial angular deviation of the shaft is then determined. Does it meet the requirements? If the requirements are not met, proceed to step three to level the drive shaft until the angular deviation meets the requirements; if the requirements are met... If the requirements are met, then this axis meets the leveling requirements and no further adjustment is needed. Return to step one to proceed with the leveling test process for the next axis, until all 7 axes meet the requirements.

[0033] Step 3: Leveling and adjusting the drive shaft: Regarding the initial axial deviation If the requirements are not met, first determine the degree of influence of the angular deviation in the vertical and horizontal directions. The direction with the greater influence represents the direction in which the shaft needs to be leveled. For wing drive shaft systems, if the vertical angular deviation has a greater influence, it means the shaft is deflected vertically; if the horizontal angular deviation has a greater influence, it means the shaft is deflected forward or backward. For power drive shafts and fuselage drive shaft systems, if the vertical angular deviation has a greater influence, it means the shaft is deflected vertically; if the horizontal angular deviation has a greater influence, it means the shaft is deflected left or right.

[0034] Secondly, determine the specific deviation of the shaft in a certain direction. Since the dial indicator reading is positive when the probe is compressed (moved inwards) and negative when pulled outwards (moved outwards), the direction with the larger probe reading indicates the specific deviation of the shaft that needs leveling. For the vertical direction of the wing drive shaft system, if the probe reading is larger above than below (…), If the probe reading is higher than the reading at the rear, it indicates that the shaft is tilted upwards and requires shims to be added above for leveling; conversely, if it is tilted downwards, shims need to be added below for leveling. For the horizontal direction of the wing drive shaft system, if the probe reading is higher at the front than at the rear (…), it indicates that the shaft is tilted upwards and requires shims to be added above for leveling. If the probe reading is higher at the top than at the bottom, it indicates that the shaft is tilted forward and needs to be leveled by adding shims in front. Conversely, if the probe reading is lower, it needs to be leveled by adding shims in the rear. For the vertical direction between the power drive shaft and the machine body drive shaft system, if the probe reading is higher at the top than at the bottom ( If the probe reading is higher on the left than on the right, it indicates that the shaft is tilted upwards and requires shims to be added for leveling; conversely, if it is lower, shims need to be added for leveling. For the power drive shaft and the machine body drive shaft system in the horizontal direction, if the probe reading is higher on the left than on the right ( If the axis is tilted to the left, a shim needs to be added on the left side for leveling; conversely, a shim needs to be added on the right side for leveling.

[0035] Furthermore, the placement of shims needs to consider the actual layout of the quadcopter. For the wing drive shaft system, leveling can be achieved by adding shims at the wing-fuselage connection; the leveling result is relatively independent and not coupled with the fuselage or power drive shaft system. For the fuselage and power drive shaft system, considering engine installation requirements and internal structural layout, as well as the impact of shim placement on actual leveling, analysis results indicate three possible shim placement locations, such as... Figure 6 As shown, it includes (1) shim position 1: the connection between the main reducer and the fuselage frame 4; (2) shim position 2: the connection between the front fuselage drive shaft and the fuselage frame 6; (3) shim position 3: the connection between the main reducer and the fuselage frame 3. Taking shim position 1 as an example, Figure 7 This diagram illustrates the addition of a shim when drive shaft 3 deflects to the right.

[0036] For the thickness of the shim The calculation was performed based on the law of similar triangles and the position of the shims.

[0037] in, and These represent the thickness of the shims added in the vertical and horizontal directions, respectively. and The angular deviation is perpendicular to the horizontal direction. and These represent the distances between the shim locations and the axis in the vertical and horizontal directions, respectively, for the wing drive shaft system. This refers to the distance between the wing-fuselage junction and the wing axis, for the fuselage and engine drive shaft system. These are the distances between shim positions 1, 2, and 3 and the engine drive shaft and the transmission shaft, respectively.

[0038] Finally, based on the determined shim positions and thicknesses, shims were added and leveled at the corresponding locations on the drive shaft. The coaxiality measuring fixture was then reinstalled, and the momentum value of the dial indicator after one revolution of the probe was recorded. The angular deviation of the drive shaft after adding shims was then calculated. ,

[0039] in, and The offsets in the vertical and horizontal directions were measured using a dial indicator, respectively. To fix the radius at the dial indicator. Determine the adjustment result. Does it meet the requirements? If the requirements are not met, repeat step three until the angular deviation meets the requirements.

[0040] If after adjustment If the requirements are met, proceed to the leveling test process for the next shaft, until all shafts meet the requirements. The engine drive shaft is the reference shaft and must be leveled first. The wing drive shaft system is relatively independent and has minimal coupling effect with the fuselage and power drive shaft systems; therefore, it can be leveled last. The leveling sequence after decoupling the drive shaft systems is as follows: engine front drive shaft (shaft 1), main reducer rear drive shaft (shaft 2), rear fuselage reducer front drive shaft (shaft 3), left front wing drive shaft (shaft 4), right front wing drive shaft (shaft 5), left rear wing drive shaft (shaft 6), and right rear wing drive shaft (shaft 7).

[0041] This method is not limited to quadcopter aircraft, but is also applicable to shaft leveling of other complex mechanical transmission systems with narrow internal spaces where optical paths cannot be established.

[0042] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0043] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for measuring and leveling the coaxiality of a transmission system of a four-tilt rotor aircraft, characterized in that, Includes the following steps: The radial offset of the shafts at both ends of the diaphragm coupling of the drive shaft was measured using a contact probe. Based on the law of similar triangles, the radial offset is converted into the angular deviation of the drive shaft; Based on the comparison between the angular deviation and the preset threshold value, determine whether to perform shim leveling on the drive shaft; The multiple drive shafts are measured and leveled sequentially according to the preset decoupling sequence until the angular deviation of all drive shafts meets the preset requirements.

2. The method for measuring and leveling the coaxiality of a four-tilt rotor aircraft transmission system according to claim 1, characterized in that, Install brackets at the input and output ends of the diaphragm coupling, fix the dial indicator probe to either bracket and make the probe perpendicular to the shaft surface; rotate the two shafts synchronously and collect the dial indicator variation of the probe at multiple rotation angles. First calculate the measurement error and verify the installation validity, then extract the dial indicator variation at key angles to calculate the radial offset.

3. The method for measuring and leveling the coaxiality of a four-tilt rotor aircraft transmission system according to claim 2, characterized in that, The formula for calculating the radial offset is as follows: ； in, These represent the percentage changes in the dial gauge readings of the probe when it rotates to 0°, 90°, 180°, 270°, 360°, 450°, 540°, and 630°, respectively.

4. The method for measuring and leveling the coaxiality of a four-tilt rotor aircraft transmission system according to claim 2, characterized in that, Radial offset includes vertical offset X and horizontal offset Y, and the calculation formula is as follows: ； ； in, This represents the change in the dial gauge value of the probe when it rotates 0°. This represents the change in the dial gauge reading of the probe when it rotates 90°. This represents the change in the dial gauge reading of the probe when it rotates 180°. This represents the percentage change in the dial gauge of the probe when it rotates 270°.

5. The method for measuring and leveling the coaxiality of a four-tilt rotor aircraft transmission system according to claim 1, characterized in that, The calculation of the angular deviation includes: According to the law of similar triangles, the angular deviation between the vertical and horizontal directions is calculated as follows: ； ； in, To fix the radius at the dial gauge. The offset in the vertical direction is measured using a dial indicator. The horizontal offset is measured using a dial indicator. and These represent the vertical and horizontal angular deviations at the center of the drive shaft diaphragm coupling assembly, and the axial angular deviations, respectively. It consists of two angular deviation components located in two mutually perpendicular planes: ； in, Indicates the angular deviation in the vertical direction. This indicates the angular deviation in the horizontal direction. The angular deviation of the drive shaft must meet the following requirements. ； in, The acceptable angular deviation threshold value for drive shaft leveling is set based on the model and experience.

6. The method for measuring and leveling the coaxiality of a four-tilt rotor aircraft transmission system according to claim 1, characterized in that, The shim leveling process includes: determining the main leveling direction based on the magnitude of the angular deviation component, determining the specific offset position of the shaft by combining the positive and negative probe readings, selecting the corresponding shim installation position and calculating the shim thickness, adding the shim according to the calculated thickness, and then re-measuring the angular deviation until it is qualified.

7. The method for measuring and leveling the coaxiality of a four-tilt rotor aircraft transmission system according to claim 6, characterized in that, For the thickness of the shim The calculation is based on the law of similar triangles and the position of the shim. The specific calculation formula is as follows: ； ； in, and These represent the thickness of the shims added in the vertical and horizontal directions, respectively. and The angular deviation is perpendicular to the horizontal direction. and These represent the distances between the shim locations and the axis in the vertical and horizontal directions, respectively, for the wing drive shaft system. This refers to the distance between the wing-fuselage junction and the wing axis, for the fuselage and engine drive shaft system. These are the distances between shim positions 1, 2, and 3 and the engine drive shaft and the transmission shaft, respectively.

8. The method for measuring and leveling the coaxiality of a four-tilt rotor aircraft transmission system according to claim 1, characterized in that, After leveling, record the momentum value of the dial indicator after one revolution of the probe, and calculate the angular deviation of the drive shaft after adding shims. , ； in, and The offsets in the vertical and horizontal directions were measured using a dial indicator, respectively. To fix the radius at the dial indicator, determine the adjustment... Does it meet the requirements? If the requirements are not met, repeat the leveling process until the angular deviation meets the requirements.

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