A method for selecting optimal suspension parameters of an underfloor equipment of a railway vehicle

Abstract

This invention provides a method for selecting optimal suspension parameters for undercarriage equipment of a rail vehicle, belonging to the field of rail vehicle design technology. When determining the suspension stiffness of undercarriage equipment, this method comprehensively considers the equipment's self-excited frequency and the car body's first-order vertical bending frequency. It can determine the optimal suspension stiffness of the equipment under three-point and four-point suspension modes, improve the car body's vertical bending stiffness, ensure the vehicle's running stability, reduce the vibration intensity of undercarriage equipment, and improve the structural fatigue reliability of connection parts.

Description

Technical Field

[0001] This invention belongs to the field of rail vehicle design technology, specifically relating to a method for selecting optimal suspension parameters for undercarriage equipment of a rail vehicle. Background Technology

[0002] The underside of rail vehicles houses a large number of devices, such as diesel engines, generators, air compressors, air cylinders, fuel tanks, sewage tanks, transformers, inverters, etc. These devices vary in weight, ranging from tens of kilograms to several tons, and are distributed throughout the vehicle body. They can also be categorized into active devices (such as diesel engines and generators) and passive devices (such as air cylinders and fuel tanks) based on whether they have their own excitation source. These devices are suspended from the underside of the vehicle body using different suspension methods; some are rigidly connected directly to the frame, while others are elastically connected to the frame using rubber components.

[0003] For equipment with relatively small mass (generally less than 0.5t), the suspension method has a smaller impact on local vibrations of the vehicle body, and a rigid suspension is typically used. However, for large-mass equipment, especially those with their own excitation sources, using a rigid suspension will not only reduce the vehicle's vertical stiffness and deteriorate its running stability, but also exacerbate vibration intensity and reduce the structural fatigue reliability of connecting parts. Therefore, for such equipment, an elastic suspension must be used. When using an elastic suspension, the selection of suspension stiffness is crucial. Appropriate stiffness is essential to maximizing the advantages of elastic suspension; conversely, improper selection of suspension parameters can lead to severe vehicle vibrations, suspension component detachment and breakage, and other safety-related accidents.

[0004] When the mass, moment of inertia, and installation location of equipment are fixed, selecting the appropriate suspension stiffness for under-vehicle equipment requires consideration of the equipment's natural frequency, the vehicle's bending frequency, and other factors. Currently, vehicle manufacturers and shock absorber suppliers typically assume a rigid vehicle body when selecting shock absorbers, neglecting the natural frequency of the elastic body. This leads to a one-sided selection of suspension stiffness, sometimes causing problems in the application field. Therefore, improvements are necessary. Summary of the Invention

[0005] The technical problem solved by this invention is to provide a method for selecting the optimal suspension parameters for undercarriage equipment of a rail vehicle. When determining the suspension stiffness of the undercarriage equipment, this invention comprehensively considers the self-excited frequency of the equipment and the first-order vertical bending frequency of the vehicle body. It can determine the optimal suspension stiffness of the equipment under three-point and four-point suspension modes, improve the vertical bending stiffness of the vehicle body, ensure the smooth operation of the vehicle, reduce the vibration intensity of the undercarriage equipment, and improve the structural fatigue reliability of the connection parts.

[0006] The technical solution adopted in this invention is: a method for selecting optimal suspension parameters for undercarriage equipment of a rail vehicle, comprising the following steps:

[0007] (1) Determine the basic parameters of the undercarriage equipment according to the physical object of the undercarriage equipment;

[0008] (2) Determine the first-order vertical bending frequency fcb of the car body according to the finite element result of the car body, and determine the excitation frequency fej of the active equipment according to the idle speed, number of cylinders and stroke of the power unit. The suspension frequency of the undercarriage equipment should avoid the above two frequencies as much as possible. Determine the upper limit value femax of the suspension frequency according to the vibration isolation principle.

[0009] (3) According to the upper limit value femax of the suspension frequency determined in step (2), specify the suspension frequency fe of the equipment, and thus obtain the total vertical dynamic stiffness kd of the equipment suspension, kd = (2 × π × fe) 2 × m; According to the ratio Nds of the vertical dynamic and static stiffness, further obtain the total vertical static stiffness kstotal of the equipment suspension, kstotal = kd / Nds;

[0010] (4) Determine the optimization target values: the maximum static compression Z0max of the rubber shock absorbers at each suspension point, the maximum difference △Z0max in the static compression between the rubber shock absorbers at each suspension point. It is required that the static compression value zi0 at the i-th suspension point and the static compression difference △zi0 at the i-th suspension point satisfy Max(zi0) < Z0max, Max(△zi0) < △Z0max; If the results obtained by the following Method 1 and Method 2 do not meet these two conditions, it means that the stiffness of the rubber shock absorbers at each suspension point does not meet the requirements and needs to be reselected; where, i is the number of suspension points 1, 2, 3, 4;

[0011] Among them, for the N-point support method, select according to the following method:

[0012] Method 1: Assume that the rubber shock absorbers at each suspension point adopt the same stiffness, then the stiffness of each suspension point equally divides the total stiffness kis0, kis0 = kstotal / N. If the above requirements of step (4) are met, the stiffness selection is completed; If not, it means that rubber shock absorbers with the same stiffness cannot be selected, and it automatically flows to Method 2;

[0013] Method 2: Assume two rubber vibration dampers with different stiffnesses are selected. Suspension points 1 and 2 use one stiffness k1s0 = k2s0, and the remaining suspension points use the other stiffness kns0, where kns0 = (kstotal - k1s0 - k2s0) / n. First, assume the stiffness of suspension points 1 and 2, starting with the smaller one. Since the total stiffness is constant, the stiffness of the remaining suspension points n can be obtained, starting with the larger one. Under this set of stiffnesses, the maximum static compression of each suspension point and the difference in maximum static compression of each suspension point can be obtained. Then, with a certain increase Δks0 = kstotal / / P, where P is the optimization number, the suspension points are increased... The stiffness of suspension points 1 and 2 is obtained, as well as the stiffness of the other suspension points. Under this set of stiffness, the maximum static compression of each suspension point and the difference between the maximum static compression of each suspension point can be obtained. Repeat this process P times, where P is the number of times to select the optimal value, to obtain the maximum static compression of each suspension point and the difference between the maximum static compression of each suspension point under P sets of suspension stiffness. Finally, check whether there is a stiffness value that meets the conditions. If multiple sets of stiffness meet the conditions, select the set of stiffness with the smallest difference in static compression as the optimal stiffness value, and indicate that the optimal stiffness value meets the requirements. Proceed to step (6). If none of the stiffness values ​​meet the requirements, proceed to step (5).

[0014] (5) Increase the equipment suspension frequency fe under step (3) appropriately, and repeat step (4) until the optimal stiffness value is found.

[0015] (6) The set of stiffness values ​​selected by step (4) or step (5) is the vertical static stiffness. Based on the ratio of longitudinal vertical and transverse vertical stiffness Nxz and Nyz and the dynamic static stiffness (Nds), the three-dimensional dynamic stiffness of each suspension point can be obtained, thus obtaining the stiffness matrix of the system. Finally, the six natural frequencies of the equipment suspension system can be obtained.

[0016] (7) Based on the type of rubber in the rubber damper, determine the damping coefficient of the rubber damper, and obtain the system isolation rate curve and the isolation rate at any frequency.

[0017] In step (4) above, the three-point support method is selected according to the following method:

[0018] Method 1: Assuming that the same stiffness rubber damper is used at each suspension point, the stiffness of each suspension point is equal to the total stiffness kis0, kis0 = kstotal / 3. If the above requirements of step (4) are met, the stiffness selection is completed; if not, it means that the same stiffness rubber damper cannot be selected, and it will automatically flow to Method 2.

[0019] Method 2: Assume two rubber vibration dampers with different stiffnesses are selected. Suspension points 1 and 2 use one stiffness k1s0 = k2s0, and suspension point 3 uses another stiffness k3s0, where k3s0 = kstotal - k1s0 - k2s0. First, assume the stiffness of suspension points 1 and 2, starting with the smaller one. Since the total stiffness is constant, the stiffness of suspension point 3 can be obtained, starting with the larger one. Under this set of stiffnesses, the maximum static compression of each suspension point and the difference in maximum static compression of each suspension point can be obtained. Then, with a certain increase Δks0 = kstotal / / P, where P is the optimization number, increase the stiffness of suspension point 1... The stiffness of point 2 is obtained, and the stiffness of suspension point 3 is also obtained. Under this set of stiffness, the maximum static compression of each suspension point and the difference between the maximum static compression of each suspension point can be obtained. Repeat this process P times, where P is the number of times to select the optimal value, to obtain the maximum static compression of each suspension point and the difference between the maximum static compression of each suspension point under P sets of suspension stiffness. Finally, check whether there is a stiffness value that meets the conditions. If multiple sets of stiffness meet the conditions, select the set of stiffness with the smallest difference in static compression as the optimal stiffness value, and indicate that the optimal stiffness value meets the requirements. Proceed to step (6). If none of the stiffness values ​​meet the requirements, proceed to step (5).

[0020] In step (4) above, the four-point support method is selected according to the following method:

[0021] Method 1: Assuming that the same stiffness rubber damper is used at each suspension point, the stiffness of each suspension point is equal to the total stiffness kis0, kis0 = kstotal / 4. If the above requirements of step (4) are met, the stiffness selection is completed; if not, it means that the same stiffness rubber damper cannot be selected, and it will automatically flow to Method 2.

[0022] Method 2: Assume two rubber vibration dampers with different stiffnesses are selected. Suspension points 1 and 2 use one stiffness k1s0 = k2s0, and suspension points 3 and 4 use another stiffness k3s0 = k4s0 = (kstotal - k1s0 - k2s0) / 2. First, assume the stiffness of suspension points 1 and 2, starting with the smaller one. Since the total stiffness is constant, the stiffness of suspension points 3 and 4 can be obtained, starting with the larger one. Under this set of stiffnesses, the maximum static compression of each suspension point and the difference in maximum static compression of each suspension point can be obtained. Then, with a certain increase Δks0 = kstotal / P Let P be the number of optimization attempts. Increasing the stiffness of suspension points 1 and 2 also yields the stiffness of suspension points 3 and 4. Under this set of stiffnesses, the maximum static compression of each suspension point and the difference between the maximum static compressions of each suspension point can be obtained. This process is repeated P times, where P is the number of optimization attempts, to obtain the maximum static compression of each suspension point and the difference between the maximum static compressions of each suspension point under N sets of suspension stiffnesses. Finally, it is checked whether there is a stiffness value that meets the conditions. If multiple sets of stiffnesses meet the conditions, the set with the smallest difference in static compression is selected as the optimal stiffness value. If none of the stiffness values ​​meet the conditions, the process automatically proceeds to method three.

[0023] Method 3: Continue to use two rubber vibration dampers with different stiffnesses. Suspension points 1 and 4 use one stiffness k1s0 = k4s0, while suspension points 2 and 3 use another stiffness k2s0 = k3s0 = (kstotal - k1s0 - k4s0) / 2. First, assume the stiffness of suspension points 1 and 4, starting with the smaller value. Since the total stiffness is constant, the stiffness of suspension points 2 and 3 can be obtained, starting with the larger value. Under this set of stiffnesses, the maximum static compression of each suspension point and the difference in maximum static compression between each suspension point can be obtained. Then, increase the suspension damper by a certain increment Δks0 = kstotal / P, where P is the optimization number. Stiffnesses at points 1 and 4 are obtained, as are stiffnesses at suspension points 2 and 3. Under this set of stiffnesses, the maximum static compression of each suspension point and the difference between the maximum static compressions of each suspension point can be obtained. This process is repeated P times, where P is the number of times the selection is performed, to obtain the maximum static compression of each suspension point and the difference between the maximum static compressions of each suspension point under P sets of suspension stiffnesses. Finally, it is checked whether there are any stiffness values ​​that meet the conditions. If multiple sets of stiffnesses meet the conditions, the set of stiffnesses with the smallest difference in static compression is selected as the optimal stiffness value. It is also stated that the optimal stiffness value meets the requirements, and step (6) is performed. If none of the stiffness values ​​meet the requirements, step (5) is performed.

[0024] In step (1) above, the basic parameters include mass m, moment of inertia Ixx, Iyy, Izz, center of gravity coordinates, and suspension point coordinates.

[0025] Advantages of this invention compared to existing technologies:

[0026] 1. When determining the suspension stiffness of the equipment under the vehicle, this solution comprehensively considers the self-excited frequency of the equipment and the first-order vertical bending frequency of the vehicle body. It can determine the optimal suspension stiffness of the equipment under three-point and four-point suspension, improve the vertical bending stiffness of the vehicle body, ensure the smooth operation of the vehicle, reduce the vibration intensity of the equipment under the vehicle, and improve the structural fatigue reliability of the connection parts.

[0027] 2. This plan first considers using rubber vibration dampers with the same stiffness at each suspension point, and secondly considers using two different stiffnesses. It does not consider using three or four different stiffnesses, taking into account the practicality and economy in actual engineering.

[0028] 3. This solution combines actual production practices and takes into account the actual manufacturing process level. It allows for flexible setting of the longitudinal and transverse stiffness ratios and the dynamic and static stiffness ratios of the rubber vibration damper, making it easy to obtain the three-dimensional stiffness of the rubber vibration damper. This provides a theoretical basis for the selection of rubber vibration dampers and has strong engineering practical value. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the three-point support structure of the device in this invention;

[0030] Figure 2 This is a flowchart illustrating the logic for selecting the optimal stiffness in the three-point support suspension method of this invention.

[0031] Figure 3 This is a schematic diagram of the four-point support structure of the device in this invention;

[0032] Figure 4 This is a flowchart illustrating the logic for selecting the optimal stiffness in the four-point support suspension method of this invention. Detailed Implementation

[0033] 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.

[0034] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0035] Please see Figure 1-4 The embodiments of the present invention are described in detail below.

[0036] A method for selecting optimal suspension parameters for undercarriage equipment of a rail vehicle is proposed. This method comprehensively considers the self-excited frequency of the equipment and the first-order vertical bending frequency of the vehicle body when determining the suspension stiffness of the undercarriage equipment, and can determine the optimal suspension stiffness of the equipment under three-point and four-point suspension modes.

[0037] Example 1: When the equipment uses three-point support, the optimal suspension parameters are determined using the following steps. See Appendix. Figure 1 A schematic diagram of the three-point support structure of the equipment is attached. Figure 2 A flowchart illustrating the logic for selecting the optimal stiffness for a three-point support suspension system.

[0038] (1) Determine the basic parameters of the equipment under the vehicle based on the actual equipment, including mass m, moment of inertia (Ixx, Iyy, Izz), center of gravity coordinates, and suspension point coordinates;

[0039] (2) Determine the first-order vertical bending frequency fcb of the vehicle body based on the finite element analysis results. Determine the excitation frequency fej of the active equipment based on the idle speed, number of cylinders, and number of strokes of the power unit (fej = idle speed × number of cylinders / (60 × Q), where Q = 1 when the power unit is a 2-stroke unit and Q = 2 when it is a 4-stroke unit). The suspension frequency of the under-vehicle equipment should avoid the above two frequencies as much as possible. Determine the upper limit value of the suspension frequency femax based on the vibration isolation principle. (The suspension frequency should be kept away from the excitation frequency as much as possible) or ).

[0040] (3) Based on the upper limit value of the suspension frequency femax determined in step (2), specify the suspension frequency fe of the equipment (start with a smaller value and try to calculate it. If the value is found to be unsuitable through step (4), modify the value), thereby obtaining the total vertical dynamic stiffness of the equipment suspension kd, kd=(2×π×fe). 2 ×m; Based on the vertical dynamic and static stiffness ratio Nds (Nds is a property of the rubber material, which can be provided by the supplier), the total vertical static stiffness of the equipment suspension kstotal=kd / Nds is obtained;

[0041] (4) Determine the optimization target values: the maximum static compression Z0max of the rubber shock absorbers at each suspension point, and the maximum difference △Z0max in the static compression between the rubber shock absorbers at each suspension point. It is required that the static compression value zi0 at the i-th suspension point and the static compression difference △zi0 at the i-th suspension point satisfy Max(zi0) < Z0max and Max(△zi0) < △Z0max. If the results obtained by Method 1 and Method 2 below do not meet these two conditions, it means that the stiffness of the rubber shock absorbers at each suspension point does not meet the requirements and needs to be reselected. Here, i is the number of suspension points 1, 2, 3, 4;

[0042] Among them, for the 3-point support method, select according to the following method:

[0043] Method 1: Assume that the rubber shock absorbers at each suspension point have the same stiffness. Then the stiffness of each suspension point evenly divides the total stiffness kis0, and kis0 = kstotal / 3. If the above requirements in step (4) are met, the stiffness selection is completed. If not, it means that rubber shock absorbers with the same stiffness cannot be selected, and it automatically flows to Method 2;

[0044] Method 2: Assume that two different stiffness rubber shock absorbers are selected. The suspension points 1 and 2 use one kind of stiffness k1s0 = k2s0, and the suspension point 3 uses another kind of stiffness k3s0, where k3s0 = kstotal - k1s0 - k2s0. First, assume the stiffness of suspension points 1 and 2 (starting from the smaller value). Since the total stiffness is fixed, the stiffness of suspension point 3 can be obtained (starting from the larger value). At this set of stiffness values, the maximum static compression of each suspension point and the maximum difference in the static compression of each suspension point can be obtained. Then, with a certain increment △ks0 = kstotal / P, where P is the number of optimization times, increase the stiffness of suspension points 1 and 2, and at the same time obtain the stiffness of suspension point 3. At this set of stiffness values, the maximum static compression of each suspension point and the maximum difference in the static compression of each suspension point can be obtained. Repeat this P times, where P is the number of optimization times, to obtain the maximum static compression of each suspension point and the maximum difference in the static compression of each suspension point under P sets of suspension stiffness values. Finally, check whether there are stiffness values that meet the conditions. If there are multiple sets of stiffness that meet the requirements, select the set of stiffness with the smallest static compression difference as the optimal stiffness value, and at the same time indicate that this optimal stiffness value meets the requirements and proceed to step (6). If all stiffness values do not meet the requirements, proceed to step (5).

[0045] (5) Appropriately increase the equipment suspension frequency fe in step (3), and repeat step (4) until the optimal stiffness value is found.

[0046] (6) The set of stiffness values ​​selected by step (4) or step (5) is the vertical static stiffness. Based on the ratios of longitudinal and transverse stiffness Nxz and Nyz and the ratio of dynamic and static stiffness Nds, the three-dimensional dynamic stiffness of each suspension point can be obtained, thus obtaining the stiffness matrix of the system. Finally, the six natural frequencies of the equipment suspension system can be obtained.

[0047] (7) Based on the type of rubber in the rubber damper, determine the damping coefficient of the rubber damper, and obtain the system isolation rate curve and the isolation rate at any frequency.

[0048] Example 2: When the equipment uses four-point support, the optimal suspension parameters are determined using the following steps. See Appendix. Figure 3 A schematic diagram of the four-point support structure of the equipment is attached. Figure 4 A flowchart illustrating the logic for selecting the optimal stiffness for a three-point support suspension system.

[0049] (1) Determine the basic parameters of the equipment under the vehicle based on the actual equipment, including mass m, moment of inertia (Ixx, Iyy, Izz), center of gravity coordinates, and suspension point coordinates;

[0050] (2) Determine the first-order vertical bending frequency fcb of the vehicle body based on the finite element results of the vehicle body, and determine the excitation frequency fej of the active equipment based on the idle speed, number of cylinders, and stroke of the power unit (fej = idle speed × number of cylinders / (60 × Q), where Q = 1 when the power unit is a 2-stroke and Q = 2 when it is a 4-stroke). The suspension frequency of the under-vehicle equipment should avoid the above two frequencies as much as possible, based on the vibration isolation principle (the suspension frequency should avoid the excitation frequency as much as possible). or Determine the upper limit value of the suspension frequency, femax.

[0051] (3) Based on the upper limit value of the suspension frequency femax determined in step (2), specify the suspension frequency fe of the equipment (start with a smaller value and try to calculate it. If the value is found to be unsuitable through step (4), modify the value), thereby obtaining the total vertical dynamic stiffness of the equipment suspension kd, kd=(2×π×fe). 2 ×m; Based on the vertical dynamic and static stiffness ratio Nds (Nds is a property of the rubber material, which can be provided by the supplier), the total vertical static stiffness of the equipment suspension kstotal=kd / Nds is obtained;

[0052] (4) Determine the optimized target values: the maximum static compression Z0max of the rubber shock absorbers at each suspension point, and the maximum difference ΔZ0max in the static compression between the rubber shock absorbers at each suspension point. It is required that the static compression value zi0 at the i-th suspension point and the static compression difference Δzi0 at the i-th suspension point satisfy Max(zi0) < Z0max and Max(Δzi0) < ΔZ0max. If the results obtained by the following Method 1, Method 2, and Method 3 do not meet these two conditions, it means that the stiffness of the rubber shock absorbers at each suspension point does not meet the requirements and needs to be reselected.

[0053] Among them, for the 4-point support method, select according to the following method:

[0054] Method 1: Assume that the rubber shock absorbers at each suspension point use the same stiffness. Then the stiffness of each suspension point evenly divides the total stiffness kis0, and kis0 = kstotal / 4. If the above requirements in step (4) are met, the stiffness selection is completed. If not, it means that rubber shock absorbers with the same stiffness cannot be selected, and it automatically proceeds to Method 2.

[0055] Method 2: Assume that two different stiffness rubber shock absorbers are selected. The suspension points 1 and 2 use one stiffness k1s0 = k2s0, and the suspension points 3 and 4 use another stiffness k3s0 = k4s0 = (kstotal - k1s0 - k2s0) / 2. First, assume the stiffness of the suspension points 1 and 2 (starting from the smaller value). Since the total stiffness is fixed, the stiffness of the suspension points 3 and 4 can be obtained (starting from the larger value). Under this set of stiffness values, the maximum static compression of each suspension point and the maximum difference in the static compression of each suspension point can be obtained. Then, with a certain increase amplitude Δks0 = kstotal / P, where P is the number of optimization times, increase the stiffness of the suspension points 1 and 2, and at the same time obtain the stiffness of the suspension points 3 and 4. Under this set of stiffness values, the maximum static compression of each suspension point and the maximum difference in the static compression of each suspension point can be obtained. Repeat this process P times (P is the number of optimization times) to obtain the maximum static compression of each suspension point and the maximum difference in the static compression of each suspension point under N sets of suspension stiffness values. Finally, check whether there are stiffness values that meet the conditions. If there are multiple sets of stiffness that meet the requirements, select the set of stiffness with the smallest difference in static compression as the optimal stiffness value. If all stiffness values do not meet the requirements, it automatically proceeds to Method 3.

[0056] Method 3: Continue to use two rubber vibration dampers with different stiffnesses. Suspension points 1 and 4 use one stiffness k1s0 = k4s0, while suspension points 2 and 3 use another stiffness k2s0 = k3s0 = (kstotal - k1s0 - k4s0) / 2. First, assume the stiffness of suspension points 1 and 4 (starting from the smaller one). Since the total stiffness is constant, the stiffness of suspension points 2 and 3 can be obtained (starting from the larger one). Under this set of stiffnesses, the maximum static compression of each suspension point and the difference in maximum static compression between each suspension point can be obtained. Then, increase the suspension by a certain increment Δks0 = kstotal / P, where P is the optimization number. Stiffnesses at points 1 and 4 are obtained, as are stiffnesses at suspension points 2 and 3. Under this set of stiffnesses, the maximum static compression of each suspension point and the difference between the maximum static compressions of each suspension point can be obtained. This process is repeated P times (P being the number of times the selection is performed) to obtain the maximum static compression of each suspension point and the difference between the maximum static compressions of each suspension point under N sets of suspension stiffnesses. Finally, it is checked whether there are any stiffness values ​​that meet the conditions. If multiple sets of stiffnesses meet the conditions, the set of stiffnesses with the smallest difference in static compression is selected as the optimal stiffness value. It is also stated that the optimal stiffness value meets the requirements, and step (6) is performed. If none of the stiffness values ​​meet the requirements, step (5) is performed.

[0057] (5) Increase the equipment suspension frequency fe under step (3) appropriately, and repeat step (4) until the optimal stiffness value is found.

[0058] (6) The set of stiffness values ​​selected by step (4) or step (5) is the vertical static stiffness. Based on the ratios of longitudinal and transverse stiffness Nxz and Nyz and the ratio of dynamic and static stiffness Nds, the three-dimensional dynamic stiffness of each suspension point can be obtained, thus obtaining the stiffness matrix of the system. Finally, the six natural frequencies of the equipment suspension system can be obtained.

[0059] (7) Based on the type of rubber in the rubber damper, determine the damping coefficient of the rubber damper, and obtain the system isolation rate curve and the isolation rate at any frequency.

[0060] This method comprehensively considers the equipment's self-excited frequency and the vehicle's first-order vertical bending frequency when determining the suspension stiffness of the equipment under the vehicle. It can determine the optimal suspension stiffness of the equipment under three-point and four-point suspension, improve the vehicle's vertical bending stiffness, ensure the vehicle's running stability, reduce the vibration intensity of the equipment under the vehicle, and improve the structural fatigue reliability of the connection parts.

[0061] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

[0062] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for selecting optimal suspension parameters for undercarriage equipment of a rail vehicle, characterized in that: It includes the following steps: (1) Determine its basic parameters according to the physical vehicle under - equipment; (2) Determine the first-order vertical bending frequency fcb of the vehicle body based on the finite element results of the vehicle body; determine the excitation frequency fej of the active equipment based on the idle speed, number of cylinders and stroke of the power unit; and determine the upper limit value of the suspension frequency femax based on the vibration isolation principle. <min(fcb,fej) / ; (3) Based on the upper limit value of the suspension frequency femax determined in step (2), specify the suspension frequency fe of the equipment, and thus obtain the total vertical dynamic stiffness kd of the equipment suspension, kd=(2×π×fe) 2 ×m, where m is the mass of the equipment under the vehicle; based on the ratio of vertical dynamic stiffness to static stiffness Nds, the total vertical static stiffness of the equipment suspension kstotal=kd / Nds is obtained; (4) Determine the optimization target values: the maximum static compression Z0max of the rubber shock absorbers at each suspension point, the maximum difference △Z0max in static compression between the rubber shock absorbers at each suspension point. It is required that the static compression value zi0 at the i - th suspension point and the static compression difference △zi0 at the i - th suspension point satisfy Max(zi0) < Z0max and Max(△zi0) < △Z0max. If the results obtained by Method 1 and Method 2 below do not meet these two conditions, it means that the stiffness of the rubber shock absorbers at each suspension point does not meet the requirements and needs to be re - selected. Here, i is the number of suspension points 1, 2, 3, 4; For the N - point support method, select according to the following method: Method 1: Assume that the rubber shock absorbers at each suspension point use the same stiffness. Then the stiffness at each suspension point equally divides the total stiffness kis0, kis0 = kstotal / N. If the above requirements in step (4) are met, the stiffness selection is completed. If not, it means that rubber shock absorbers with the same stiffness cannot be selected, and it automatically goes to Method 2; Method 2: Assume that two different stiffness rubber shock absorbers are selected. Suspension points 1 and 2 use one stiffness k1s0 = k2s0, and the remaining suspension points use another stiffness kns0, where kns0=(kstotal - k1s0 - k2s0) / n. First, assume the stiffness of suspension points 1 and 2, then the stiffness of the remaining suspension points n can be obtained. Under this set of stiffnesses, the maximum static compression at each suspension point and the maximum difference in static compression at each suspension point can be obtained. Then, with a certain increment △ks0 = kstotal / P, P is the number of optimization times, increase the stiffness of suspension points 1 and 2, and at the same time obtain the stiffness of the remaining suspension points. Under this set of stiffnesses, the maximum static compression at each suspension point and the maximum difference in static compression at each suspension point can be obtained. Repeat this P times, P is the number of optimization times, to obtain the maximum static compression at each suspension point and the maximum difference in static compression at each suspension point under P sets of suspension stiffnesses. Finally, check whether there are stiffness values that meet the conditions. If there are multiple sets of stiffnesses that meet the requirements, select the set of stiffnesses with the smallest difference in static compression as the optimal stiffness value, and at the same time indicate that the optimal stiffness value meets the requirements and proceed to step (6); if all stiffness values do not meet the requirements, proceed to step (5); (5) Appropriately increase the suspension frequency fe of the equipment in step (3), and perform step (4) again until the optimal stiffness value is found; (6) The set of stiffness values selected through step (4) or step (5) is the vertical static stiffness. According to the longitudinal - vertical, transverse - vertical stiffness ratios Nxz and Nyz and the dynamic - static stiffness Nds, the three - dimensional dynamic stiffness at each suspension point can be obtained, and thus the stiffness matrix of the system can be obtained. Finally, the 6 natural frequencies of the equipment suspension system can be obtained; (7) Determine the damping coefficient of the rubber shock absorber according to the rubber type of the rubber shock absorber, and the vibration isolation rate curve of the system and the vibration isolation rate at any frequency can be obtained.

2. The method for selecting optimal suspension parameters for undercarriage equipment of a rail vehicle according to claim 1, characterized in that: In step (4) above, for the three - point support method, select according to the following method: Method 1: Assuming that the same stiffness rubber damper is used at each suspension point, the stiffness of each suspension point is equal to the total stiffness kis0, kis0 = kstotal / 3. If the above requirements of step (4) are met, the stiffness selection is completed; if not, it means that the same stiffness rubber damper cannot be selected, and it will automatically flow to Method 2. Method 2: Assume that two rubber vibration dampers with different stiffnesses are selected. Suspension points 1 and 2 use one stiffness k1s0=k2s0, and suspension point 3 uses another stiffness k3s0, k3s0=kstotal-k1s0-k2s0. First, assume the stiffness of suspension points 1 and 2, then the stiffness of suspension point 3 can be obtained. Under this set of stiffnesses, the maximum static compression of each suspension point and the difference between the maximum static compressions of each suspension point can be obtained. Then, increase the stiffness of suspension points 1 and 2 by a certain increment Δks0=kstotal / P, where P is the number of optimizations, and at the same time obtain the stiffness of suspension point 3. Under this set of stiffnesses, the maximum static compression of each suspension point and the difference between the maximum static compressions of each suspension point can be obtained. Repeat this process P times, where P is the number of optimizations, to obtain the maximum static compression of each suspension point and the difference between the maximum static compressions of each suspension point under P sets of suspension stiffnesses. Finally, check whether there is a stiffness value that meets the conditions. If multiple sets of stiffnesses meet the conditions, select the set of stiffnesses with the smallest difference in static compressions as the optimal stiffness value, and indicate that the optimal stiffness value meets the requirements, and proceed to step (6). If none of the stiffness values ​​meet the requirements, proceed to step (5).

3. The method for selecting optimal suspension parameters for undercarriage equipment of a rail vehicle according to claim 1, characterized in that: In step (4) above, the four-point support method is selected according to the following method: Method 1: Assuming that the same stiffness rubber damper is used at each suspension point, the stiffness of each suspension point is equal to the total stiffness kis0, kis0 = kstotal / 4. If the above requirements of step (4) are met, the stiffness selection is completed; if not, it means that the same stiffness rubber damper cannot be selected, and it will automatically flow to Method 2. Method 2: Assume two types of rubber vibration dampers with different stiffnesses are selected. Suspension points 1 and 2 use one stiffness k1s0=k2s0, and suspension points 3 and 4 use the other stiffness k3s0=k4s0=( kstotal-k1s0-k2s0) / 2; First, assume the stiffness of suspension points 1 and 2, then obtain the stiffness of suspension points 3 and 4. Under this set of stiffnesses, obtain the maximum static compression of each suspension point and the difference between the maximum static compressions of each suspension point; Then, increase the stiffness of suspension points 1 and 2 by a certain increment Δks0=kstotal / P, where P is the number of optimizations, and obtain the stiffness of suspension points 3 and 4. Under this set of stiffnesses, obtain the maximum static compression of each suspension point and the difference between the maximum static compressions of each suspension point; Repeat this process P times, where P is the number of optimizations, to obtain the maximum static compression of each suspension point and the difference between the maximum static compressions of each suspension point under P sets of suspension stiffnesses; Finally, check if there are any stiffness values ​​that meet the conditions. If multiple sets of stiffnesses meet the conditions, select the set of stiffnesses with the smallest difference in static compressions as the optimal stiffness value. If none of the stiffness values ​​meet the conditions, automatically proceed to method three. Method 3: Continue to use two rubber vibration dampers with different stiffnesses. Suspension points 1 and 4 use one stiffness k1s0 = k4s0, and suspension points 2 and 3 use the other stiffness k2s0 = k3s0 = ( kstotal-k1s0-k4s0) / 2; First, assume the stiffness of suspension points 1 and 4, then the stiffness of suspension points 2 and 3 can be obtained. Under this set of stiffnesses, the maximum static compression of each suspension point and the difference between the maximum static compressions of each suspension point can be obtained; Then, with a certain increase △ks0=kstotal / P, where P is the number of optimizations, increase the stiffness of suspension points 1 and 4, and at the same time obtain the stiffness of suspension points 2 and 3. Under this set of stiffnesses, the maximum static compression of each suspension point and the difference between the maximum static compressions of each suspension point can be obtained; Repeat this process P times, where P is the number of optimizations, to obtain the maximum static compression of each suspension point and the difference between the maximum static compressions of each suspension point under N sets of suspension stiffnesses; Finally, check whether there is a stiffness value that meets the conditions. If multiple sets of stiffnesses meet the conditions, select the set of stiffnesses with the smallest difference in static compressions as the optimal stiffness value, and indicate that the optimal stiffness value meets the requirements, and proceed to step (6); If none of the stiffness values ​​meet the requirements, proceed to step (5).

4. The method for selecting optimal suspension parameters for undercarriage equipment of a rail vehicle according to claim 1, characterized in that: In step (1) above, the basic parameters include mass m, moment of inertia Ixx, Iyy, Izz, center of gravity coordinates, and suspension point coordinates.

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