Method and system for testing isolation performance of brake vacuum pipe

Abstract

This invention relates to a method and system for testing the vibration isolation performance of a brake vacuum tube. The testing method involves setting an excitation point and a response point on the brake vacuum tube under test; applying excitation to the excitation point and obtaining the transfer function of the response point; and obtaining the comprehensive vibration transmissibility of the brake vacuum tube under test based on the transfer function, thereby determining the comprehensive vibration isolation performance of the brake vacuum tube. This invention also provides a testing system for the vibration isolation performance of a brake vacuum tube, including a testing platform, a first support and a second support thereon, a first slide rail on the first support, and a second slide rail on the second support; sensors are arranged at both ends of the brake vacuum tube under test, the sensors are connected to a data acquisition terminal, the data acquisition terminal is connected to a computer, and the data acquisition terminal is also connected to a hammer. By applying excitation to the brake vacuum tube under test, the corresponding transfer function is obtained. This invention can accurately evaluate the vibration isolation performance of brake vacuum tubes and provides a reliable reference for the design improvement of brake vacuum tubes.

Description

Technical Field

[0001] This invention relates to the field of automotive NVH technology, specifically to a test method and system for the vibration isolation performance of brake vacuum tubes. Background Technology

[0002] Brake vacuum hoses are widely used in automotive braking systems. One end is connected to the engine, and the other end is connected to a vacuum pump, thus providing assistance to the driver when pressing the brake pedal.

[0003] Vibrations from the car engine are transmitted through the brake vacuum hoses to the vacuum pump, and then to the brake pedal. This causes the driver to experience noticeable brake pedal vibration and numbness when pressing the brake pedal, affecting driving comfort. Different brake vacuum hoses have different vibration isolation performances; the worse the vibration isolation performance, the greater the vibration transmitted from the engine to the brake pedal through the brake vacuum hose. Therefore, the vibration isolation performance of the brake vacuum hoses has a direct impact on brake pedal vibration.

[0004] Currently, the development and design of brake vacuum tubes mainly consider braking function, layout, cost, etc., and lack testing methods and evaluation means for the vibration isolation performance of brake vacuum tubes. Therefore, it is necessary to design a testing method and system for the vibration isolation performance of brake vacuum tubes. Summary of the Invention

[0005] The purpose of this invention is to provide a test method and system for the vibration isolation performance of brake vacuum tubes, so as to accurately evaluate the vibration isolation performance of brake vacuum tubes, provide a reliable reference for the design improvement of brake vacuum tubes, and thus improve driving comfort.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for testing the vibration isolation performance of a brake vacuum tube includes the following steps:

[0008] Excitation and response points are set on the brake vacuum tube under test, and the test system is arranged based on the excitation and response points.

[0009] The excitation points on the brake vacuum tube under test are excited at different frequencies along the X, Y and Z directions of the vehicle coordinate system, and the transfer functions of each response point in the X, Y and Z directions are obtained.

[0010] Based on the transfer functions of each response point in the X, Y, and Z directions, the vibration transmissibility of the brake vacuum tube under test in the X, Y, and Z directions is obtained.

[0011] The comprehensive vibration transmissibility of the brake vacuum tube under test is obtained based on the vibration transmissibility in the X, Y and Z directions, and the comprehensive vibration isolation performance of the brake vacuum tube under test is determined based on the comprehensive vibration transmissibility.

[0012] Preferably, the excitation point is located near the end of the brake vacuum tube to be tested that is used for connection with the engine;

[0013] The response points include two points, A and B. Point A is located near the end of the brake vacuum tube under test that is connected to the engine, and point B is located near the end of the brake vacuum tube under test that is connected to the vacuum pump.

[0014] Preferably, the excitation points on the brake vacuum tube under test are excited at different frequencies along the X, Y, and Z directions of the vehicle coordinate system, and the transfer functions of each response point in the X, Y, and Z directions are obtained, including:

[0015] The excitation point on the brake vacuum tube under test is excited at different frequencies along the X direction of the vehicle coordinate system, and the transfer functions H of points A and B in the X, Y, and Z directions are obtained respectively. 1ax H 1ay H 1az and H 1bx H 1by H 1bz ;

[0016] The excitation point on the brake vacuum tube under test is excited at different frequencies along the Y direction of the vehicle coordinate system, and the transfer functions H of points A and B in the X, Y, and Z directions are obtained respectively. 2ax H 2ay H 2az and H 2bx H 2by H 2bz ;

[0017] The excitation point on the brake vacuum tube under test is excited at different frequencies along the Z direction of the vehicle coordinate system, and the transfer functions H of points A and B in the X, Y, and Z directions are obtained respectively. 3ax H 3ay H 3az and H 3bx H 3by H 3bz .

[0018] Preferably, the vibration transmissivity of the brake vacuum tube under test in the X, Y, and Z directions is obtained based on the transfer function of each response point in the X, Y, and Z directions, including;

[0019] The vibration transmissivity of the excitation in the X direction of the brake vacuum tube under test is calculated based on the transfer functions of points A and B obtained from the excitation along the X direction of the vehicle coordinate system and Formula I.

[0020]

[0021] In Equation I, H 1axH represents the transfer function of point A in the X direction obtained by the excitation along the vehicle's X direction. 1ay H represents the transfer function in the Y direction obtained from the excitation along the X direction of the vehicle at point A. 1az H represents the transfer function of point A in the Z direction obtained from the excitation along the X direction of the vehicle. 1bx H represents the transfer function of point B in the X direction corresponding to the excitation along the vehicle's X direction. 1by H represents the transfer function in the Y direction obtained from the excitation along the X direction of the vehicle at point B. 1bz FT1 represents the transfer function of point B in the Z direction obtained by the excitation along the X direction of the vehicle, and FT1 represents the vibration transmissivity of the brake vacuum tube under test obtained by the excitation along the X direction of the vehicle.

[0022] The vibration transmissivity of the brake vacuum tube under test in the Y direction is calculated based on the transfer functions of points A and B obtained from the excitation along the Y direction of the vehicle coordinate system and Formula II.

[0023]

[0024] In formula II, H 2ax H represents the transfer function of point A in the X direction corresponding to the excitation along the Y direction of the vehicle. 2ay H represents the transfer function of point A in the Y direction obtained by the excitation along the vehicle's Y direction. 2az H represents the transfer function of point A in the Z direction corresponding to the excitation along the Y direction of the vehicle. 2bx H represents the transfer function in the X direction corresponding to the excitation at point B along the Y direction of the vehicle. 2by H represents the transfer function in the Y direction at point B corresponding to the excitation along the vehicle's Y direction. 2bz FT2 represents the transfer function of point B in the Z direction obtained by the excitation along the Y direction of the vehicle, and FT2 represents the vibration transmissivity of the brake vacuum tube under test obtained by the excitation along the Y direction of the vehicle.

[0025] The vibration transmissivity of the excitation in the Z direction of the brake vacuum tube under test is calculated based on the transfer functions of points A and B obtained from the excitation along the Z direction of the vehicle coordinate system and Formula III.

[0026]

[0027] In Formula III, H 3ax H represents the transfer function of point A in the X direction corresponding to the excitation along the Z direction of the vehicle. 3ay H represents the transfer function in the Y direction obtained from the excitation along the Z direction of the vehicle at point A. 3azH represents the transfer function of point A in the Z direction obtained by the excitation along the vehicle's Z direction. 3bx H represents the transfer function in the X direction obtained from the excitation along the Z direction of the vehicle at point B. 3by H represents the transfer function in the Y direction obtained from the excitation along the Z direction of the vehicle at point B. 3bz FT3 represents the transfer function of point B in the Z direction obtained by excitation along the Z direction of the vehicle, and FT3 represents the vibration transmissivity of the brake vacuum tube under test obtained by excitation along the Z direction of the vehicle.

[0028] Preferably, the comprehensive vibration transmissibility of the brake vacuum tube under test is obtained based on the vibration transmissibility in the X, Y, and Z directions, including:

[0029] The comprehensive vibration transmissibility of the brake vacuum tube under test is calculated based on the vibration transmissibility obtained from the excitation along the X, Y and Z directions of the vehicle and Formula IV.

[0030]

[0031] In Equation IV, FT1 represents the vibration transmissibility of the brake vacuum tube under test obtained by excitation along the X direction of the vehicle; FT2 represents the vibration transmissibility of the brake vacuum tube under test obtained by excitation along the Y direction of the vehicle; FT3 represents the vibration transmissibility of the brake vacuum tube under test obtained by excitation along the Z direction of the vehicle; and FT represents the comprehensive vibration transmissibility of the brake vacuum tube under test.

[0032] Preferably, the overall vibration isolation performance of the brake vacuum tube under test is determined based on the overall vibration transmissibility, including:

[0033] The lower the overall vibration transmissibility, the better the overall vibration isolation performance of the brake vacuum tube under test; the higher the overall vibration transmissibility, the worse the overall vibration isolation performance of the brake vacuum tube under test.

[0034] Preferably, the excitation frequency of the excitation point is between 20Hz and 200Hz.

[0035] The present invention also provides a testing system based on the testing method described herein, comprising a testing platform, wherein the testing platform is provided with a first support and a second support, the first support is provided with a first slide rail for fixing one end of the brake vacuum tube under test, and the second support is provided with a second slide rail for fixing the other end of the brake vacuum tube under test; the testing system further includes sensors for being arranged at both ends of the brake vacuum tube under test, the sensors being connected to a data acquisition terminal, the data acquisition terminal being connected to a computer, and the data acquisition terminal being connected to a force hammer, the force hammer being used to excite the brake vacuum tube under test, and the transfer function of the brake vacuum tube under test being obtained through the sensors, the data acquisition terminal, and the computer.

[0036] Preferably, the first or second slide rail can slide on the first or second support, and the first or second support can move on the test platform to adaptively adjust the arrangement position of the brake vacuum tube under test.

[0037] The beneficial effects of this invention are:

[0038] 1) The test method for the vibration isolation performance of the brake vacuum tube of the present invention applies excitation to the brake vacuum tube to simulate the vibration of the engine in a realistic manner, so as to obtain the vibration transmission rate through the brake vacuum tube in various directions, thereby accurately evaluating the vibration isolation performance of the brake vacuum tube, providing a reliable reference for the design and development of the brake vacuum tube, and thus effectively improving driving comfort. It has the advantages of convenient operation and high accuracy.

[0039] 2) The test system for the vibration isolation performance of the brake vacuum tube of the present invention adapts to different lengths, directions, sizes and structures of brake vacuum tubes by reasonably arranging the positional relationship of each component. This allows the brake vacuum tube to be simulated to be consistent with the actual assembly position during testing, ensuring the accuracy of the test results. It has promotion and application value in the field of automotive NVH technology. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the vibration isolation performance testing system for the brake vacuum tube of the present invention;

[0041] Among them, 1-test platform; 2-first support; 3-second support; 4-first slide rail; 5-second slide rail; 6-sensor; 7-data acquisition terminal; 8-computer; 9-force hammer; 10-braking vacuum tube to be tested. Detailed Implementation

[0042] The embodiments of the present invention will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the scope of protection of the present invention.

[0043] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0044] Example 1

[0045] like Figure 1 As shown, a testing system for the vibration isolation performance of a brake vacuum tube includes a testing platform 1. The testing platform 1 has a first support 2 and a second support 3. The first support 2 has a first slide rail 4 for fixing one end of the brake vacuum tube 10 under test, and the second support 3 has a second slide rail 5 for fixing the other end of the brake vacuum tube 10 under test. The first support 2 is fixed to the testing platform 1, while the second support 3 is movable on the testing platform 1. The first slide rail 4 and the first support 2 are in sliding engagement, and the second slide rail 5 and the second support 3 are in sliding engagement. During actual testing of the brake vacuum tube 10 under test, the positions of the second support 3, the first slide rail 4, and the second slide rail 5 can be adjusted to accommodate different sizes and structures of the brake vacuum tube 10 under test, ensuring that the brake vacuum tube 10 under test is consistent with the actual assembly position, thereby improving the accuracy of the test results. The testing system also includes a test platform for the brake vacuum tube under test. Sensors 6 are arranged at both the end of tube 10 that is connected to the engine and the end that is connected to the vacuum pump. The sensors 6 are acceleration vibration sensors. The acceleration vibration sensors are connected to a data acquisition terminal 7, which is connected to a computer 8. The data acquisition terminal 7 is also connected to a hammer 9. The hammer 9 excites the end of the brake vacuum tube 10 under test that is connected to the engine, and the acceleration vibration sensor obtains the corresponding vibration signal. The vibration signal is collected by the data acquisition terminal 7 and transmitted to the computer 8. The computer 8 processes the signal to obtain the transfer function of the brake vacuum tube 10 under test. The position where the hammer 9 applies excitation to the brake vacuum tube 10 under test is at the end of the brake vacuum tube 10 under test that is connected to the engine. It is better for one acceleration vibration sensor to be as close as possible to the excitation point, and the other acceleration vibration sensor is set at the end of the brake vacuum tube 10 under test that is connected to the vacuum pump.

[0046] Example 2

[0047] A method for testing the vibration isolation performance of a brake vacuum tube using the test system described in Example 1 includes the following steps:

[0048] S1. Arrange the brake vacuum tube 10 to be tested on the test system in Example 1. Set the end of the brake vacuum tube 10 to be tested that is connected to the engine as the excitation point. Set the end of the brake vacuum tube 10 to be tested that is connected to the engine as the excitation point. Set the end of the brake vacuum tube 10 to be tested that is connected to the engine as the response point A and the other end that is connected to the vacuum pump as the response point B. Arrange acceleration vibration sensors at both response point A and response point B. The closer the excitation point and response point A are, the better.

[0049] S2. Excite the excitation points on the brake vacuum tube 10 under test at different frequencies along the X, Y, and Z directions of the vehicle coordinate system, and obtain the transfer functions of each response point in the X, Y, and Z directions, specifically including:

[0050] S21. The force hammer 9 excites the excitation point on the brake vacuum tube 10 under test at different frequencies along the X direction of the vehicle coordinate system. The transfer functions H of points A and B in the X, Y and Z directions are obtained by the acceleration vibration sensor, data acquisition terminal 7 and computer 8 respectively. 1ax H 1ay H 1az and H 1bx H 1by H 1bz ;

[0051] S22. The force hammer 9 excites the excitation point on the brake vacuum tube 10 under test at different frequencies along the Y direction of the vehicle coordinate system. The transfer functions H of points A and B in the X, Y and Z directions are obtained by the acceleration vibration sensor, data acquisition terminal 7 and computer 8 respectively. 2ax H 2ay H 2az and H 2bx H 2by H 2bz ;

[0052] S23. The force hammer 9 excites the excitation point on the brake vacuum tube 10 under test along the Z direction of the vehicle coordinate system at different frequencies. The transfer functions H of points A and B in the X, Y and Z directions are obtained by the acceleration vibration sensor, data acquisition terminal 7 and computer 8 respectively. 3ax H 3ay H 3az and H 3bx H 3by H 3bz ;

[0053] The transfer function is a frequency domain curve. After the computer 8 acquires the data transmitted from the data acquisition terminal 7, it will automatically process the data through the MS software in the computer 8, and the output result includes the transfer function of the corresponding response point. Since the engine is mainly excited in the range of 20Hz-200Hz, the excitation frequency is selected in the range of 20Hz-200Hz when acquiring the transfer function in this embodiment. The X direction of the vehicle coordinate system represents the front-rear direction of the vehicle, the Y direction of the vehicle coordinate system represents the left-right direction of the vehicle, and the Z direction of the vehicle coordinate system represents the up-down direction of the vehicle.

[0054] S3. Based on the transfer functions of each response point in the X, Y, and Z directions, obtain the vibration transmissibility of the tested braking vacuum tube 10 in the X, Y, and Z directions, specifically including:

[0055] S31. Based on the excitation along the X direction of the vehicle coordinate system, obtain the transfer function H of point A. 1ax H 1ay H 1az and the transfer function H at point B 1bx H 1by H 1bz The vibration transmissivity of the excitation in the X direction corresponding to the brake vacuum tube 10 under test is calculated using Formula I.

[0056]

[0057] In Equation I, H 1ax H represents the transfer function of point A in the X direction obtained by the excitation along the vehicle's X direction. 1ay H represents the transfer function in the Y direction obtained from the excitation along the X direction of the vehicle at point A. 1az H represents the transfer function of point A in the Z direction obtained from the excitation along the X direction of the vehicle. 1bx H represents the transfer function of point B in the X direction corresponding to the excitation along the vehicle's X direction. 1by H represents the transfer function in the Y direction obtained from the excitation along the X direction of the vehicle at point B. 1bz Let FT1 represent the transfer function of point B in the Z direction corresponding to the excitation along the X direction of the vehicle, and let FT1 represent the vibration transmissivity of the brake vacuum tube 10 under test corresponding to the excitation along the X direction of the vehicle; where, Let represent the three-dimensional vector sum of the transfer function at point A obtained corresponding to the excitation along the X direction of the vehicle. Let represent the three-dimensional vector sum of the transfer function at point B obtained corresponding to the excitation along the X direction of the vehicle.

[0058] S32. Based on the excitation along the Y direction of the vehicle coordinate system, obtain the transfer function H of point A. 2ax H 2ay H 2az and the transfer function H at point B 2bx H 2by H 2bz The vibration transmissivity of the excitation in the Y direction corresponding to the brake vacuum tube 10 under test is calculated using Formula II.

[0059]

[0060] In formula II, H 2ax H represents the transfer function of point A in the X direction corresponding to the excitation along the Y direction of the vehicle. 2ay H represents the transfer function of point A in the Y direction obtained by the excitation along the vehicle's Y direction. 2azH represents the transfer function of point A in the Z direction corresponding to the excitation along the Y direction of the vehicle. 2bx H represents the transfer function in the X direction corresponding to the excitation at point B along the Y direction of the vehicle. 2by H represents the transfer function in the Y direction at point B corresponding to the excitation along the vehicle's Y direction. 2bz FT2 represents the transfer function of point B in the Z direction corresponding to the excitation along the Y direction of the vehicle; FT2 represents the vibration transmissivity of the brake vacuum tube 10 under test corresponding to the excitation along the Y direction of the vehicle. Let represent the three-dimensional vector sum of the transfer function at point A obtained corresponding to the excitation along the Y direction of the vehicle. Let represent the three-dimensional vector sum of the transfer function at point B obtained corresponding to the excitation along the Y direction of the vehicle.

[0061] S33. Based on the excitation along the Z direction of the vehicle coordinate system, obtain the transfer function H of point A. 3ax H 3ay H 3az and the transfer function H at point B 3bx H 3by H 3bz The vibration transmissivity of the excitation in the Z direction corresponding to the brake vacuum tube 10 under test is calculated using Formula III.

[0062]

[0063] In Formula III, H 3ax H represents the transfer function of point A in the X direction corresponding to the excitation along the Z direction of the vehicle. 3ay H represents the transfer function in the Y direction obtained from the excitation along the Z direction of the vehicle at point A. 3az H represents the transfer function of point A in the Z direction obtained by the excitation along the vehicle's Z direction. 3bx H represents the transfer function in the X direction obtained from the excitation along the Z direction of the vehicle at point B. 3by H represents the transfer function in the Y direction obtained from the excitation along the Z direction of the vehicle at point B. 3bz FT3 represents the transfer function of point B in the Z direction obtained corresponding to the excitation along the Z direction of the vehicle, and FT3 represents the vibration transmissivity of the brake vacuum tube 10 under test obtained corresponding to the excitation along the Z direction of the vehicle; where, Let represent the three-dimensional vector sum of the transfer function at point A obtained corresponding to the excitation along the Z-direction of the vehicle. Let represent the three-dimensional vector sum of the transfer function at point B obtained corresponding to the excitation along the Z-direction of the vehicle.

[0064] S4. Based on the vibration transmissibility of the brake vacuum tube under test in the X, Y, and Z directions, obtain the comprehensive vibration transmissibility of the brake vacuum tube under test, and determine the comprehensive vibration isolation performance of the brake vacuum tube under test based on the comprehensive vibration transmissibility, specifically including:

[0065] S41. The comprehensive vibration transmission rate of the brake vacuum tube 10 under test is calculated based on the vibration transmission rate FT1 obtained by the excitation along the X direction of the vehicle, the vibration transmission rate FT2 obtained by the excitation along the Y direction of the vehicle, the vibration transmission rate FT3 obtained by the excitation along the Z direction of the vehicle, and Formula IV.

[0066]

[0067] In Equation IV, FT1 represents the vibration transmissivity of the brake vacuum tube 10 under test obtained by excitation along the X direction of the vehicle; FT2 represents the vibration transmissivity of the brake vacuum tube 10 under test obtained by excitation along the Y direction of the vehicle; FT3 represents the vibration transmissivity of the brake vacuum tube 10 under test obtained by excitation along the Z direction of the vehicle; and FT represents the comprehensive vibration transmissivity of the brake vacuum tube 10 under test.

[0068] S42. The overall vibration isolation performance of the brake vacuum tube 10 under test can be accurately evaluated by the FT value. The smaller the FT, the better the overall vibration isolation performance of the brake vacuum tube 10 under test; the larger the FT, the worse the overall vibration isolation performance of the brake vacuum tube under test. The FT value can provide a reliable reference for the vibration isolation performance of the brake vacuum tube in design and development.

[0069] In summary, the testing method for the vibration isolation performance of brake vacuum tubes of the present invention applies excitation to the brake vacuum tube to realistically simulate engine vibration, thereby obtaining the vibration transmission rate in various directions through the brake vacuum tube. This accurately evaluates the vibration isolation performance of the brake vacuum tube, providing a reliable reference for the design and development of brake vacuum tubes, and ultimately effectively improving driving comfort. It has the advantages of convenient operation and high accuracy. The testing system for the vibration isolation performance of brake vacuum tubes of the present invention, through the reasonable arrangement of the positional relationships of various components, adapts to different lengths, orientations, sizes, and structures of brake vacuum tubes. This ensures that the brake vacuum tube is simulated to be consistent with the actual assembly position during testing, guaranteeing the accuracy of the test results. It has significant application value in the field of automotive NVH technology.

[0070] The above embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.

Claims

1. A test method for the vibration isolation performance of a brake vacuum tube, characterized in that, Includes the following steps: An excitation point and a response point are set on the brake vacuum tube under test, and a test system is arranged based on the set excitation point and response point; the excitation point is set near the end of the brake vacuum tube under test that is used to connect with the engine; the response point includes two points, A and B, where point A is set near the end of the brake vacuum tube under test that is used to connect with the engine, and point B is set near the end of the brake vacuum tube under test that is used to connect with the vacuum pump. The excitation points on the brake vacuum tube under test are excited at different frequencies along the X, Y and Z directions of the vehicle coordinate system, and the transfer functions of each response point in the X, Y and Z directions are obtained. Based on the transfer functions of each response point in the X, Y, and Z directions, the vibration transmissibility of the brake vacuum tube under test in the X, Y, and Z directions is obtained. Based on the vibration transmissivity of the brake vacuum tube under test in the X, Y and Z directions, the comprehensive vibration transmissivity of the brake vacuum tube under test is obtained, and the comprehensive vibration isolation performance of the brake vacuum tube under test is determined based on the comprehensive vibration transmissivity. Specifically, the excitation points on the brake vacuum tube under test are excited at different frequencies along the X, Y, and Z directions of the vehicle coordinate system, and the transfer functions of each response point in the X, Y, and Z directions are obtained. This includes: exciting the excitation points on the brake vacuum tube under test at different frequencies along the X direction of the vehicle coordinate system, and obtaining the transfer functions H of points A and B in the X, Y, and Z directions respectively. 1ax H 1ay H 1az and H 1bx H 1by H 1bz ; Specifically, based on the transfer functions of each response point in the X, Y, and Z directions, the vibration transmissibility of the tested braking vacuum tube in the X, Y, and Z directions is obtained, including: The vibration transmissivity of the excitation in the X direction of the brake vacuum tube under test is calculated based on the transfer functions of points A and B obtained from the excitation along the X direction of the vehicle coordinate system and Formula I. （Ⅰ） In Equation I, H 1ax H represents the transfer function of point A in the X direction obtained by the excitation along the vehicle's X direction. 1ay H represents the transfer function in the Y direction obtained from the excitation along the X direction of the vehicle at point A. 1az H represents the transfer function of point A in the Z direction obtained from the excitation along the X direction of the vehicle. 1bx H represents the transfer function of point B in the X direction corresponding to the excitation along the vehicle's X direction. 1by H represents the transfer function in the Y direction obtained from the excitation along the X direction of the vehicle at point B. 1bz Let represent the transfer function in the Z direction obtained from the excitation along the X direction of the vehicle at point B. This represents the vibration transmissivity of the brake vacuum tube under test corresponding to the excitation along the X direction of the vehicle.

2. The test method for the vibration isolation performance of the brake vacuum tube according to claim 1, characterized in that, The excitation points on the brake vacuum tube under test are excited at different frequencies along the X, Y, and Z directions of the vehicle coordinate system, and the transfer functions of each response point in the X, Y, and Z directions are obtained. This also includes: The excitation point on the brake vacuum tube under test is excited at different frequencies along the Y direction of the vehicle coordinate system, and the transfer functions H of points A and B in the X, Y, and Z directions are obtained respectively. 2ax H 2ay H 2az and H 2bx H 2by H 2bz ; The excitation point on the brake vacuum tube under test is excited at different frequencies along the Z direction of the vehicle coordinate system, and the transfer functions H of points A and B in the X, Y, and Z directions are obtained respectively. 3ax H 3ay H 3az and H 3bx H 3by H 3bz .

3. The test method for the vibration isolation performance of the brake vacuum tube according to claim 2, characterized in that, Based on the transfer functions of each response point in the X, Y, and Z directions, the vibration transmissibility of the tested braking vacuum tube in the X, Y, and Z directions is obtained, and the following is also included: The vibration transmissivity of the brake vacuum tube under test in the Y direction is calculated based on the transfer functions of points A and B obtained from the excitation along the Y direction of the vehicle coordinate system and Formula II. （Ⅱ） In formula II, H 2ax H represents the transfer function of point A in the X direction corresponding to the excitation along the Y direction of the vehicle. 2ay H represents the transfer function of point A in the Y direction obtained by the excitation along the vehicle's Y direction. 2az H represents the transfer function of point A in the Z direction corresponding to the excitation along the Y direction of the vehicle. 2bx H represents the transfer function in the X direction corresponding to the excitation at point B along the Y direction of the vehicle. 2by H represents the transfer function in the Y direction at point B corresponding to the excitation along the vehicle's Y direction. 2bz Let represent the transfer function in the Z direction corresponding to the excitation along the Y direction of the vehicle at point B. This represents the vibration transmissivity of the brake vacuum tube under test corresponding to the excitation along the Y direction of the vehicle. The vibration transmissivity of the excitation in the Z direction of the brake vacuum tube under test is calculated based on the transfer functions of points A and B obtained from the excitation along the Z direction of the vehicle coordinate system and Formula III. （Ⅲ） In Formula III, H 3ax H represents the transfer function of point A in the X direction corresponding to the excitation along the Z direction of the vehicle. 3ay H represents the transfer function in the Y direction obtained from the excitation along the Z direction of the vehicle at point A. 3az H represents the transfer function of point A in the Z direction obtained by the excitation along the vehicle's Z direction. 3bx H represents the transfer function in the X direction obtained from the excitation along the Z direction of the vehicle at point B. 3by H represents the transfer function in the Y direction obtained from the excitation along the Z direction of the vehicle at point B. 3bz Let represent the transfer function of point B in the Z direction obtained by the excitation along the vehicle's Z direction. This represents the vibration transmissivity of the brake vacuum tube under test corresponding to the excitation along the Z-direction of the vehicle.

4. The test method for the vibration isolation performance of the brake vacuum tube according to claim 3, characterized in that, Based on the vibration transmissibility of the brake vacuum tube under test in the X, Y, and Z directions, the comprehensive vibration transmissibility of the brake vacuum tube under test is obtained, including: The comprehensive vibration transmissibility of the brake vacuum tube under test is calculated based on the vibration transmissibility obtained from the excitation along the X, Y and Z directions of the vehicle and Formula IV. （Ⅳ） In formula IV, This represents the vibration transmissivity of the brake vacuum tube under test corresponding to the excitation along the X direction of the vehicle. This represents the vibration transmissivity of the brake vacuum tube under test corresponding to the excitation along the Y direction of the vehicle. This represents the vibration transmissivity of the brake vacuum tube under test corresponding to the excitation along the Z-direction of the vehicle. This represents the overall vibration transmissibility of the brake vacuum tube under test.

5. The test method for the vibration isolation performance of the brake vacuum tube according to claim 1, characterized in that, The overall vibration isolation performance of the brake vacuum tube under test is determined based on the overall vibration transmissibility, including: The lower the overall vibration transmissibility, the better the overall vibration isolation performance of the brake vacuum tube under test; the higher the overall vibration transmissibility, the worse the overall vibration isolation performance of the brake vacuum tube under test.

6. The test method for the vibration isolation performance of the brake vacuum tube according to claim 1, characterized in that, The excitation frequency of the excitation point is between 20Hz and 200Hz.

7. A test system based on the test method according to any one of claims 1 to 6, characterized in that, The test system includes a test platform (1), on which a first support (2) and a second support (3) are provided. The first support (2) is provided with a first slide rail (4) for fixing one end of the brake vacuum tube (10) under test, and the second support (3) is provided with a second slide rail (5) for fixing the other end of the brake vacuum tube (10) under test. The test system also includes sensors (6) arranged at both ends of the brake vacuum tube (10) under test. The sensors (6) are connected to a data acquisition terminal (7), which is connected to a computer (8). The data acquisition terminal (7) is also connected to a hammer (9). The hammer (9) is used to excite the brake vacuum tube (10) under test, and the transfer function of the brake vacuum tube (10) under test is obtained through the sensors (6), the data acquisition terminal (7) and the computer (8).

8. The testing system according to claim 7, characterized in that, The first slide rail (4) or the second slide rail (5) can slide on the first support (2) or the second support (3), and the first support (2) or the second support (3) can move on the test platform (1) to adapt the arrangement position of the brake vacuum tube (10) to be tested.

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