Modal testing device and method for multi-section transmission shaft

Abstract

A modal testing device and method for a multi-section transmission shaft, comprising a fixing frame, the fixing frame comprising pillars and a fixing plate, pillars being vertically arranged at both ends of the bottom surface of the fixing plate, an elastic middle lifting mechanism being vertically arranged in the middle of the bottom surface of the fixing plate, elastic side lifting mechanisms being vertically and symmetrically arranged on both sides of the bottom surface of the fixing plate, the side lifting mechanisms being hoisted at both ends of a double-section transmission shaft, a middle elastic sleeve being sleeved in the middle of the double-section transmission shaft, an outer wall of the middle elastic sleeve being connected to the middle lifting mechanism; a transfer mechanism of a lifting structure being installed at the bottom of the double-section transmission shaft; a force hammer being arranged on one side of the fixing frame; vibration frequency detection components being installed at intervals on the outer wall of the double-section transmission shaft; the spring lifting ring of the present invention has low stiffness, and also reduces the influence of the stiffness of the intermediate support on the natural frequency of the transmission shaft, and uses the same spring lifting rope to mitigate the displacement difference of the two shafts at the intermediate support caused by vertical jumping.

Description

Technical Field

[0001] The invention belongs to the technical field of automobile vibration testing, and in particular relates to a modal testing device and method for a multi-section transmission shaft. Background Art

[0002] With the development of the automobile industry, modern automobiles have higher and higher requirements for the efficiency, strength, durability, vibration and noise of the drive shaft, especially in terms of vibration and noise. In view of the problem that the drive shaft is subject to self-external excitation, which causes strong vibration and abnormal noise in certain frequency ranges, some improvement plans have been given through test analysis, such as adding an intermediate support with elastic and damping elements at the universal joints between two or more sections of the drive shaft to compensate for installation errors and displacement caused by engine movement and frame deformation during driving; and as an active vibration isolation link, it is used to block or isolate the vibration excitation on the drive shaft from the frame and body.

[0003] However, the addition of an intermediate support for a multi-section transmission shaft makes its modal analysis somewhat difficult. Because it has elastic components, there is a rigid-flexible coupling between the transmission shaft and the intermediate support. When the transmission shaft vibrates vertically, the vertical displacement of the transmission shaft from the equilibrium position at the intermediate support causes additional excitation, which affects the measurement results. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a modal testing device for a multi-section transmission shaft, and the specific technical solution is as follows:

[0005] A modal testing device for a multi-section transmission shaft comprises a fixing frame, the fixing frame comprises pillars and a fixing plate, pillars are vertically arranged at both ends of the bottom surface of the fixing plate, an elastic middle lifting mechanism is vertically arranged in the middle of the bottom surface of the fixing plate, elastic side lifting mechanisms are vertically and symmetrically arranged on both sides of the bottom surface of the fixing plate, the side lifting mechanisms are hoisted at both ends of a double-section transmission shaft, a middle elastic sleeve is sleeved on the middle of the double-section transmission shaft, and the outer wall of the middle elastic sleeve is connected to the middle lifting mechanism; a transfer mechanism of a lifting structure is installed at the bottom of the double-section transmission shaft; a force hammer is arranged on one side of the fixing frame, and the force hammer is used to hammer the double-section transmission shaft to simulate an exciter; vibration frequency detection components are installed at intervals on the outer wall of the double-section transmission shaft.

[0006] Furthermore, the double-section transmission shaft includes a first transmission rod, a long axis body, an intermediate connecting piece, a short axis body and a second transmission rod; one end of the long axis body is provided with a first transmission rod, and the other end is provided with an intermediate connecting piece, one end of the short axis body is provided with an intermediate connecting piece, and the other end is provided with a second transmission rod, and the outer walls of the long axis body and the short axis body are both equipped with vibration frequency detection components.

[0007] Furthermore, the vibration frequency detection component includes a first vibration frequency detection mechanism, a second vibration frequency detection mechanism, a third vibration frequency detection mechanism and a fourth vibration frequency detection mechanism; the first vibration frequency detection mechanism and the second vibration frequency detection mechanism are installed on the long axis body at intervals, the first vibration frequency detection mechanism and the second vibration frequency detection mechanism are staggered, and the third vibration frequency detection mechanism and the fourth vibration frequency detection mechanism are installed on the short axis body at intervals.

[0008] Furthermore, the first vibration frequency detection mechanism includes a strap, which is tied to the outer wall of the long axis body. The outer wall of the strap is provided with a pocket, and a three-axis acceleration sensor is embedded in the pocket.

[0009] Furthermore, the middle lifting mechanism includes a first spring lifting rope and a first spring lifting ring, wherein the first spring lifting ring is attached to the outer wall of the middle elastic ring, the first spring lifting ring is arranged at the bottom end of the first spring lifting rope, and the first spring lifting rope is arranged on the bottom surface of the fixing plate.

[0010] Furthermore, the side lifting mechanism includes a second spring lifting rope and a second spring lifting ring, the second spring lifting ring is mounted on the first transmission rod or the second transmission rod, the second spring lifting ring is arranged at the bottom end of the second spring lifting rope, and the second spring lifting rope is arranged on the bottom surface of the fixed plate.

[0011] Furthermore, the transfer mechanism includes a bottom plate, a pneumatic rod, a top plate, a support rod and a roller; a pneumatic rod is provided on the surface of the bottom plate, a top plate is provided on the top end of the pneumatic rod, support rods are vertically provided at both ends of the surface of the top plate, and a support plate is provided on the top end of the support rod.

[0012] A modal testing method for a multi-section transmission shaft, the testing method comprising the following steps:

[0013] S1, the transfer mechanism transfers the double-section transmission shaft to the bottom of the fixed frame;

[0014] S2, installing the first vibration frequency detection mechanism and the second vibration frequency detection mechanism on the outer wall of the long axis body, and installing the third vibration frequency detection mechanism and the fourth vibration frequency detection mechanism on the outer wall of the short axis body;

[0015] S3, the middle lifting mechanism is assembled to connect the middle elastic ring of the double-section transmission shaft, and the side lifting mechanism is assembled to connect the two ends of the double-section transmission shaft; after the lifting is completed, the transfer mechanism is separated; and the double-section transmission shaft is adjusted to a horizontal suspended state;

[0016] S4. Determine the annular knocking area on the long axis and the short axis respectively, and establish a virtual coordinate system on the double-section transmission shaft, where the axis of the double-section transmission shaft is the x direction, the vertical direction is the z direction, and the horizontal direction perpendicular to the x axis is the y direction;

[0017] S5. Use a hammer to strike each striking area in the y direction, and strike the transmission shaft 5 times in each striking area from the starting point, and record the corresponding data measured by the three-dimensional acceleration transmission device; after measuring the y direction, use a hammer to strike each striking area in the z direction, and strike the transmission shaft 5 times in each striking area, and record the corresponding data measured by the three-dimensional acceleration transmission device; process the data by a computer to obtain a set of data matrices;

[0018] S6. Transpose the data matrix to obtain the transposed matrix of the transmission shaft, and remove the x-direction data measured by the three-axis acceleration transmitter; then determine the natural frequencies of the long axis and short axis of the double-section transmission shaft through bandwidth selection, pole screening and vibration mode analysis.

[0019] The beneficial effects of the present invention are:

[0020] 1. The spring ring has a small stiffness, which also reduces the influence of the intermediate support stiffness on the natural frequency of the transmission shaft. The same spring rope is used to reduce the displacement difference between the two shafts caused by vertical jump at the intermediate support.

[0021] 2. The test method provided by the present invention can accurately obtain the modal parameters of a multi-section transmission shaft. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic structural diagram of a modal testing device for a multi-section transmission shaft of the present invention is shown;

[0023] Figure 2 A schematic structural diagram of a first vibration frequency detection mechanism of the present invention is shown;

[0024] Figure 3 A schematic diagram of the transfer mechanism structure of the present invention is shown;

[0025] Figure 4 A virtual coordinate schematic diagram of a double-section transmission shaft of the present invention is shown;

[0026] As shown in the figure: 1. fixing frame; 101. pillar; 102. fixing plate; 2. double-section transmission shaft; 21. first transmission rod; 22. long axis; 23. intermediate connecting piece; 24. short axis; 25. second transmission rod; 3. first vibration frequency detection mechanism; 31. binding belt; 311. pocket; 32. three-way acceleration sensor; 4. second vibration frequency detection mechanism; 5. third vibration frequency detection mechanism; 6. fourth vibration frequency detection mechanism; 7. middle lifting mechanism; 71. first spring lifting rope; 72. first spring lifting ring; 8. side lifting mechanism; 81. second spring lifting rope; 82. second spring lifting ring; 9. transfer mechanism; 91. bottom plate; 92. pneumatic rod; 93. top plate; 94. support rod; 941. support plate; 95. roller; 10. hammer; 11. control host; 12. middle elastic ring. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0028] like Figure 1 As shown, a modal test device for a multi-section transmission shaft comprises a fixing frame 1, wherein the fixing frame 1 comprises a pillar 101 and a fixing plate 102, wherein pillars 101 are vertically arranged at both ends of the bottom surface of the fixing plate 102, an elastic middle lifting mechanism 7 is vertically arranged in the middle of the bottom surface of the fixing plate 102, and elastic side lifting mechanisms 8 are vertically and symmetrically arranged on both sides of the bottom surface of the fixing plate 102, wherein the side lifting mechanisms 8 are hoisted at both ends of a double-section transmission shaft 2, and a middle elastic sleeve 12 is sleeved in the middle of the double-section transmission shaft 2, and the outer wall of the middle elastic sleeve 12 is connected to the middle lifting mechanism 7. Lifting mechanism 7; a transfer mechanism 9 of a lifting structure is installed at the bottom of the double-section transmission shaft 2; a force hammer 10 is provided on one side of the fixed frame 1, and the force hammer 10 is used to hammer the double-section transmission shaft 2 to simulate the exciter; vibration frequency detection components are installed at intervals on the outer wall of the double-section transmission shaft 2; the force hammer is used to make the double-section transmission shaft vibrate to simulate the actual working state; the lifting mechanisms all adopt elastic structures because the lifting mechanisms have low stiffness, which can reduce the influence of the intermediate support stiffness on the natural frequency of the transmission shaft, and reduce the displacement difference of the double-section transmission shaft at the intermediate support due to vertical jump.

[0029] As an improvement of the above technical solution, the double-section transmission shaft 2 includes a first transmission rod 21, a long axis body 22, an intermediate connecting piece 23, a short axis body 24 and a second transmission rod 25; one end of the long axis body 22 is provided with a first transmission rod 21, and the other end is provided with an intermediate connecting piece 23, one end of the short axis body 24 is provided with an intermediate connecting piece 23, and the other end is provided with a second transmission rod 25, and the outer walls of the long axis body 22 and the short axis body 24 are both equipped with a vibration frequency detection component; by arranging the vibration frequency detection component on the long axis body and the short axis body, it is possible to detect the vibration process of the double-section transmission shaft and determine whether the frequencies between the long axis body and the short axis body are consistent.

[0030] As an improvement of the above technical solution, the vibration frequency detection component includes a first vibration frequency detection mechanism 3, a second vibration frequency detection mechanism 4, a third vibration frequency detection mechanism 5 and a fourth vibration frequency detection mechanism 6; the first vibration frequency detection mechanism 3 and the second vibration frequency detection mechanism 4 are installed on the long axis body 22 at intervals, the first vibration frequency detection mechanism 3 and the second vibration frequency detection mechanism 4 are staggered, the third vibration frequency detection mechanism 5 and the fourth vibration frequency detection mechanism 6 are installed on the short axis body at intervals, and the two vibration frequency detection mechanisms on each transmission column are staggered, so as to realize the detection of different positions of the transmission column. The detection mechanisms on the two transmission columns are in the same position, so as to ensure the uniformity of the detection positions on the two transmission columns and ensure the accuracy of the detection data.

[0031] like Figure 2 As shown, the first vibration frequency detection mechanism 3 includes a strap 31, and the strap 31 is tied to the outer wall of the long axis body 22. The outer wall of the strap 31 is provided with a pocket 311, and a three-axis acceleration sensor 32 is embedded in the pocket 311; the three-axis acceleration sensor is used to detect the excitation in the three directions of x, y, and z, and the pocket is designed to store the three-axis acceleration sensor. The strap is tied to the transmission column to achieve the positioning of the three-axis acceleration sensor.

[0032] like Figure 1 As shown, the middle lifting mechanism 7 includes a first spring lifting rope 71 and a first spring lifting ring 72. The first spring lifting ring 72 is tied to the outer wall of the middle elastic ring 12. The first spring lifting ring 72 is arranged at the bottom end of the first spring lifting rope 71. The first spring lifting rope 71 is arranged on the bottom surface of the fixed plate 102. The spring lifting ring has a small stiffness, which also reduces the influence of the intermediate support stiffness on the natural frequency of the transmission shaft. The same spring lifting rope is used to reduce the displacement difference of the two shafts at the intermediate support due to vertical jump.

[0033] like Figure 1As shown, the side lifting mechanism 8 includes a second spring lifting rope 81 and a second spring lifting ring 82. The second spring lifting ring 82 is mounted on the first transmission rod 21 or the second transmission rod 25. The second spring lifting ring 82 is arranged at the bottom end of the second spring lifting rope 81. The second spring lifting rope 81 is arranged on the bottom surface of the fixed plate 102. The side lifting mechanism is used to lift the two ends of the double-section transmission shaft.

[0034] like Figure 3 As shown, the transfer mechanism 9 includes a base plate 91, a pneumatic rod 92, a top plate 93, a support rod 94 and a roller 95; a pneumatic rod 92 is provided on the surface of the base plate 91, a top plate 93 is provided at the top of the pneumatic rod 92, support rods 94 are vertically provided at both ends of the surface of the top plate 93, and a support plate 941 is provided at the top of the support rod 94; rollers 95 are installed at the four corners of the bottom surface of the base plate 91; the design of the roller is convenient for movement, the pneumatic rod can drive the lifting and lowering movement of the double-section transmission shaft, and the support plate can hold up the long axis body and the short axis body, so as to facilitate the stable transfer of the double-section transmission shaft.

[0035] A modal testing method for a multi-section transmission shaft, the testing method comprising the following steps:

[0036] S1. The transfer mechanism transfers the double-section transmission shaft to the bottom of the fixed frame; the double-section transmission shaft 2 is placed on the transfer mechanism 9, and the two support plates 941 are respectively placed at the bottom of the long shaft body 22 and the bottom of the short shaft body 24, and the transfer mechanism 9 is moved as a whole so that the double-section transmission shaft 2 is placed at the bottom of the lifting mechanism;

[0037] S2, install the first vibration frequency detection mechanism 3 and the second vibration frequency detection mechanism 4 on the outer wall of the long axis body 22, and install the third vibration frequency detection mechanism 5 and the fourth vibration frequency detection mechanism 6 on the outer wall of the short axis body 24; this step is used to install each three-axis acceleration transmission device, specifically: place the three-axis acceleration sensor in the pocket, and then tie the strap 31 to the long axis body 22 or the short axis body 24, so that the three-axis acceleration sensor is fixed on the outer wall of the transmission column;

[0038] S3, the middle lifting mechanism is assembled to connect the middle elastic ring of the double-section transmission shaft, and the side lifting mechanism is assembled to connect the two ends of the double-section transmission shaft; after the lifting is completed, the transfer mechanism is separated; the double-section transmission shaft is adjusted to a horizontal suspended state; during the lifting, the first spring lifting ring 72 is placed outside the middle elastic ring 12, and the second spring lifting ring 82 is hoisted on the first transmission rod 21 and the second transmission rod 25 at both ends of the double-section transmission shaft;

[0039] S4, such as Figure 4As shown, the positions of the annular knocking areas are respectively determined on the long axis body 22 and the short axis body 24. The number of the knocking areas on the long axis body 22 is more than that on the short axis body 24. A virtual coordinate system is established on the double-section transmission shaft. The axis of the double-section transmission shaft is the x-direction, the vertical direction is the z-direction, and the horizontal direction perpendicular to the x-axis is the y-direction. The exemplary long axis body 22 has 8 annular knocking areas, and the short axis body 24 has 5 annular knocking areas. The annular design is used to ensure that the hammering point can be the z-axis hammering or the y-axis direction.

[0040] S5. Use a hammer to strike each striking area in the y direction. From the starting point, strike the transmission shaft 5 times in each striking area and record the corresponding data measured by the three-dimensional acceleration transmission device. After measuring the y direction, use a hammer to strike each striking area in the z direction. In each striking area, strike the transmission shaft 5 times and record the corresponding data measured by the three-dimensional acceleration transmission device. Finally, a set of data matrix will be obtained. The hammering in the y and z directions can realize detection in two directions, increase the detection range, and improve the detection accuracy. When hammering, it should be ensured that the striking points in the y and z directions on the striking area are consistent.

[0041] S6. Transpose the data matrix to obtain the transposed matrix of the transmission shaft, and remove the x-direction data measured by the three-axis acceleration actuator; then determine the natural frequencies of the long axis and short axis of the double-section transmission shaft through bandwidth selection, pole screening and vibration mode analysis; the three-axis acceleration sensor receives the excitation and vibration response signals, and then processes the relevant data through analog / digital conversion and fast Fourier transform, calculates various functions, and obtains the parameters such as the natural frequencies of each order, damping ratio and vibration mode of the multi-section transmission shaft; the above analysis and calculation process is completed by the control host 11.

[0042] In order to verify the accuracy of the above method, the following verification test was carried out: a modal test model of a double-section transmission shaft was established in the data acquisition software. The three-dimensional model of the double-section transmission shaft was subjected to finite element modal analysis to verify the test results. First, the finite element mesh was divided, the material properties of each part were added, the rigid connection simulated the connection of the cross-axis universal joint, and the middle support part was simulated by a spring unit. Through this method, the natural frequency and displacement cloud map of the transmission shaft were calculated. Compared with the results of the test method, it was found that the first and second order natural frequencies of the double-section transmission shaft were very close, which also proved the accuracy of this test method within a certain error.

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A modal testing device for a multi-section transmission shaft, characterized in that: It comprises a fixing frame, which comprises pillars and a fixing plate, pillars are vertically arranged at both ends of the bottom surface of the fixing plate, an elastic middle lifting mechanism is vertically arranged in the middle of the bottom surface of the fixing plate, and elastic side lifting mechanisms are vertically and symmetrically arranged on both sides of the bottom surface of the fixing plate, the side lifting mechanisms are hoisted at both ends of the double-section transmission shaft, a middle elastic sleeve is sleeved on the middle part of the double-section transmission shaft, and the outer wall of the middle elastic sleeve is connected to the middle lifting mechanism; a transfer mechanism of a lifting structure is installed at the bottom of the double-section transmission shaft; a force hammer is arranged on one side of the fixing frame, and the force hammer is used to hammer the double-section transmission shaft to simulate the exciter; vibration frequency detection components are installed at intervals on the outer wall of the double-section transmission shaft; The double-section transmission shaft comprises a first transmission rod, a long shaft, an intermediate connecting piece, a short shaft and a second transmission rod; one end of the long shaft is provided with the first transmission rod and the other end is provided with the intermediate connecting piece, one end of the short shaft is provided with the intermediate connecting piece and the other end is provided with the second transmission rod, and the middle elastic ring is provided on the outside of the intermediate connecting piece; The transfer mechanism includes a bottom plate, a pneumatic rod, a top plate, a support rod and a roller; a pneumatic rod is provided on the surface of the bottom plate, a top plate is provided on the top end of the pneumatic rod, support rods are vertically provided at both ends of the surface of the top plate, and a support plate is provided on the top end of the support rod.

2. A modal testing device for a multi-section transmission shaft according to claim 1, characterized in that: The outer walls of the long axis body and the short axis body are both equipped with vibration frequency detection components.

3. A modal testing device for a multi-section transmission shaft according to claim 2, characterized in that: The vibration frequency detection component includes a first vibration frequency detection mechanism, a second vibration frequency detection mechanism, a third vibration frequency detection mechanism and a fourth vibration frequency detection mechanism; the first vibration frequency detection mechanism and the second vibration frequency detection mechanism are installed at intervals on the long axis body, the first vibration frequency detection mechanism and the second vibration frequency detection mechanism are staggered, and the third vibration frequency detection mechanism and the fourth vibration frequency detection mechanism are installed at intervals on the short axis body.

4. The modal testing device for a multi-section transmission shaft according to claim 3, characterized in that: The first vibration frequency detection mechanism comprises a strap, which is fastened to the outer wall of the long axis body. The outer wall of the strap is provided with a pocket, and a three-axis acceleration sensor is embedded in the pocket.

5. The modal testing device for a multi-section transmission shaft according to claim 3, characterized in that: The middle lifting mechanism includes a first spring lifting rope and a first spring lifting ring. The first spring lifting ring is attached to the outer wall of the middle elastic ring. The first spring lifting ring is arranged at the bottom end of the first spring lifting rope. The first spring lifting rope is arranged on the bottom surface of the fixed plate.

6. The modal testing device for a multi-section transmission shaft according to claim 3, characterized in that: The side lifting mechanism includes a second spring lifting rope and a second spring lifting ring. The second spring lifting ring is sleeved on the first transmission rod or the second transmission rod. The second spring lifting ring is arranged at the bottom end of the second spring lifting rope. The second spring lifting rope is arranged on the bottom surface of the fixed plate.

7. A modal testing method for a multi-section transmission shaft, characterized in that: The modal testing device for the multi-section transmission shaft according to claim 1 is used; the testing method comprises the following steps: S1, the transfer mechanism transfers the double-section transmission shaft to the bottom of the fixed frame; S2, installing the first vibration frequency detection mechanism and the second vibration frequency detection mechanism on the outer wall of the long axis body, and installing the third vibration frequency detection mechanism and the fourth vibration frequency detection mechanism on the outer wall of the short axis body; S3, the middle lifting mechanism is assembled to connect the middle elastic ring of the double-section transmission shaft, and the side lifting mechanism is assembled to connect the two ends of the double-section transmission shaft; after the lifting is completed, the transfer mechanism is separated; and the double-section transmission shaft is adjusted to a horizontal suspended state; S4. Determine the annular knocking area on the long axis body and the short axis body, and establish a virtual coordinate system on the double-section transmission shaft, where the axis of the double-section transmission shaft is the x direction, the vertical direction is the z direction, and the horizontal direction perpendicular to the x axis is the y direction; S5. Use a hammer to strike each striking area in the y direction, and strike the transmission shaft 5 times in each striking area from the starting point, and record the corresponding data measured by the three-dimensional acceleration transmission device; after measuring the y direction, use a hammer to strike each striking area in the z direction, and strike the transmission shaft 5 times in each striking area, and record the corresponding data measured by the three-dimensional acceleration transmission device; process the data by a computer to obtain a set of data matrices; S6. Transpose the data matrix to obtain the transposed matrix of the transmission shaft, and remove the x-direction data measured by the three-axis acceleration transmitter; then determine the natural frequencies of the long axis and short axis of the double-section transmission shaft through bandwidth selection, pole screening and vibration mode analysis.

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