Simulation analysis method for dynamic gear shifting of mechanical transmission

Abstract

The invention discloses a simulation analysis method for dynamic gear shifting of a mechanical transmission. The simulation analysis method comprises the steps that firstly, a simulation model of a gear shifting execution mechanism is established, and the gear shifting execution mechanism comprises a gear shifting rocker arm, a transverse gear shifting rod and a shifting fork; step 2, establishing a torque transmission simulation model of rotating parts, wherein the rotating parts are divided into an external rotating part and an internal rotating part of the transmission; 3, a synchronizer simulation model is established, and a synchronizer comprises a synchronizer gear hub, a synchronizer sliding gear sleeve, a synchronizer combination gear ring and a synchronizer friction ring; 4, gear shifting conditions are set, and transmission gear shifting simulation calculation is started; and step 5, outputting a simulation result and processing and analyzing data. According to the method, calculation and result comparison are conducted on different transmission design parameters, the design parameter with the optimal simulation calculation result is selected to conduct design improvement on the transmission, the research and development time cost is greatly reduced, meanwhile, more different design parameters can be compared more comprehensively, and the improvement effect is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of transmission shift simulation, and in particular relates to a simulation analysis method for dynamic shifting of a mechanical transmission. Background Art

[0002] The severity of the secondary shift ring of a mechanical transmission is an important indicator for determining the comfort of gear shifting. Currently, the main way to obtain this indicator is to conduct bench tests. By conducting a dynamic shift performance test on a transmission bench, the probability of secondary shift rings of different severity levels can be tested, thereby determining the comfort of gear shifting. This method requires testing of the actual object. When the comfort of the transmission is improved, the actual product needs to be processed according to the improvement plan, and then the bench test is carried out to verify the improvement effect. When there are multiple alternative design parameters for the improvement plan to find the optimal solution, multiple alternative plans must be trial-produced and bench-tested, and then all the results must be compared to find the optimal solution. In general, the improvement of the comfort of gear shifting in a transmission often involves the adjustment of many parameters, and each parameter adjustment also has multiple design values. If the design value of each design parameter is trial-produced and tested, the improvement cycle and difficulty will be greatly increased, and related manufacturing and testing resources will be occupied.

[0003] At present, when domestic transmission manufacturers are optimizing transmission design, they mostly screen the pre-improvement parameters through the rich experience of designers, and retain some key parameter values ​​selected by experience for trial production and testing. Although this simplifies the optimization scope and reduces certain R&D costs, subjective artificial simplification may still miss key design parameters, and subjective experience in the selection of design values ​​also needs to be obtained after comprehensive evaluation of the test results of samples with different design values. Some scholars have also studied the simulation modeling of the synchronizer shifting process, and established a synchronizer shifting process simulation model using software such as ADAMS or AMSIM, and improved the shifting performance through synchronizer simulation. However, these models are relatively simple, and only express the formula of the friction torque work to change the speed of the combined tooth through the software module, and no detailed synchronizer internal structure model is established. In the simulation of the secondary shift ring, the size of the secondary impact is only confirmed by calculating the speed difference, and the collision position of the combined tooth during the secondary impact collision and the entire collision process are not simulated, and the shifting process cannot be visualized and the relative positions of all parts at each moment can be controlled. Summary of the invention

[0004] The purpose of the present invention is to provide a simulation analysis method for dynamic shifting of a mechanical transmission, so as to solve the problems of high improvement research and development cost and long improvement cycle caused by the inaccurate simulation results of the secondary shift ring when improving the shift comfort of the existing mechanical transmission and the inability to visualize the specific collision process.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A simulation analysis method for dynamic shifting of a mechanical transmission comprises the following steps:

[0007] Step 1: Establish a simulation model of a gear shift actuator, wherein the gear shift actuator includes a gear shift rocker arm, a transverse gear shift rod and a shift fork;

[0008] Step 2: Establish a torque transmission simulation model of rotating parts, wherein the rotating parts are divided into external rotating parts of the transmission and internal rotating parts of the transmission. The external rotating parts of the transmission include the clutch driven plate and the constant meshing gear pair, and the internal rotating parts of the transmission include the first shaft, the second shaft, the second shaft gear, the intermediate shaft assembly, the reverse gear intermediate gear and the synchronizer;

[0009] Step 3: Establish a synchronizer simulation model, wherein the synchronizer includes a synchronizer gear hub, a synchronizer sliding gear sleeve, a synchronizer combined gear ring and a synchronizer friction ring;

[0010] Step 4: Set the shifting conditions and start the transmission shifting simulation calculation, including setting internal parameters, setting external parameters and simulation analysis calculation;

[0011] Step 5: Output simulation results and data processing and analysis.

[0012] Furthermore, step one includes the following sub-steps:

[0013] Step 11: Build a model for the shift rocker arm to drive the horizontal shift lever and shift knob to rotate

[0014] Among them, the shift rocker arm drives the lateral shift lever, and the speed difference between the rocker arm and the hand ball causes the deformation of the rocker arm to generate torque. The rotation of the rocker arm drives the lateral shift lever to rotate; confirm the length of the shift rocker arm and the length of the inner shift head;

[0015] Step 12, establish a model for the movement of the shift fork shaft and the shift fork through the shift head when the lateral shift lever rotates; including a force model of the shift fork shaft and the shift fork, and a kinematic model of the shift fork shaft and the shift fork after being subjected to force; the rotation of the rocker arm drives the rotation of the inner shift head, the rotation of the inner shift head produces a relative displacement with the guide block, the guide block is deformed and subjected to force, and drives the shift fork shaft and the shift fork to move.

[0016] Step 13: Establish a model in which the shift fork moves to drive the synchronizer sleeve to shift gears

[0017] In this model, the relative displacement between the shift fork and the synchronizer sleeve causes deformation, which causes the synchronizer sleeve to be subjected to the shift force. When the synchronizer sleeve is displaced by the shift force, it is also subjected to the resistance generated inside the synchronizer during the synchronization process. The shift force overcomes the resistance and pushes the sleeve forward. The resistance during the shift is fed back to the shift fork, and the movement direction of the sleeve is different when changing to different gears.

[0018] Furthermore, step 2 specifically includes the following sub-steps:

[0019] Step 21, establishing a model of the external rotating parts of the transmission, the clutch driven plate is subjected to the torque transmitted by the engine, and since the clutch is in a disconnected state during the gear shifting process, the torque transmitted by the engine is set to 0Nm, and the clutch driven plate is also subjected to the torque inside the transmission, and a simulation model of the clutch driven plate is established; wherein, the clutch rotates after being subjected to the torque, and the clutch and the transmission rotate relative to each other;

[0020] Step 22, establishing a model of the internal rotating parts of the transmission, establishing a model of a shaft rotating due to torque, a simulation model of a shaft transmitting torque to an intermediate shaft assembly through a constant mesh gear, a gear transmission model of each gear of the second shaft, and a reverse gear transmission model;

[0021] Step 23, establishing a gear transmission model, including: a force model: the gear pair rotates relatively, the tooth surface is deformed by force, the deformation generates force, and the tooth surface generates torque by force; a motion model: the gear is subjected to torque and overcomes resistance to generate rotation.

[0022] Step 3: Build a synchronizer simulation model

[0023] The synchronizer includes a synchronizer gear hub, a synchronizer sliding gear sleeve, a synchronizer combined gear ring, and a synchronizer friction ring.

[0024] Furthermore, step three specifically includes the following sub-steps:

[0025] Step 31, establishing a synchronizer simulation model according to actual synchronizer design parameters, including a locking angle between the sleeve and the outer friction ring, a locking radius, a sleeve inverted cone angle, a friction cone surface angle, a friction cone surface friction coefficient, a friction cone surface radius, a compression spring stiffness, and a pin groove shape;

[0026] The synchronizer simulation model is encapsulated as an independent module, whose input is the rotation speed of the rotating parts at both ends of the synchronizer and the displacement of the sliding sleeve, and the output is the force fed back to the sliding sleeve during the synchronization process and the synchronous torque exerted on the rotating parts at both ends of the synchronizer;

[0027] After the synchronizer sleeve is subjected to the fork force, it will be displaced in two directions. One is the axial displacement to extend the shift position. The axial displacement is mainly affected by the return resistance when the synchronizer is working. The other is the torsional displacement of the sleeve caused by the side clearance of the spline fit between the synchronizer sleeve and the synchronizer gear hub. The torsional displacement of the sleeve increases the friction resistance during the movement process.

[0028] Step 32, the main types of synchronizer structures are: single-cone synchronizer, double-cone coupled synchronizer, double-cone uncoupled synchronizer, and three-cone synchronizer; all types of synchronizer calculation models are integrated in the synchronizer module and numbered;

[0029] Step 33, all models are combined according to the internal mechanism logic of the transmission to form a transmission shift calculation simulation model, and a main shift condition setting interface is reserved for quickly adjusting input parameters.

[0030] Furthermore, step 4 specifically includes the following sub-steps:

[0031] Step 41, setting internal parameters: a. synchronizer type internal parts size parameters; b. synchronizer internal parts size parameters; c. gears and other rotating parts parameters;

[0032] Step 42, setting external parameters: a shaft speed during gear shifting, an initial gear shifting speed of a gear shifting hand ball, a gear shifting type, a gear shifting position, and a maximum peak force limit during gear shifting;

[0033] Step 43, start simulation analysis and calculation, the shift hand ball starts to move at the set speed, drives the outer shift rocker arm to swing, drives the lateral shift lever to rotate, drives the shift fork to move through the shift head, and drives the synchronizer sleeve to move, and starts shifting; after pre-synchronization, synchronization, primary shift ring, idle travel, secondary shift ring and other stages, the shift is completed.

[0034] Furthermore, step five specifically includes the following sub-steps:

[0035] Step 51, after the calculation is completed, the calculation result curve is retrieved, and the main output results are the curve of the change of the shift force over time, the curve of the change of the shift displacement over time, the curve of the change of the first axis speed over time, and the curve of the change of the second axis torque over time, which are consistent with the experimental bench;

[0036] Step 52, analyze the curve of the change of the shift force over time, and obtain the severity of the secondary shift ring in this shift simulation; adjust the locking angle of the sliding sleeve and the outer friction ring in the input parameters, re-simulate the calculation, and make a comprehensive comparison of the calculation results, select the optimal design parameters, and complete the optimization improvement of the locking angle on the secondary shift ring.

[0037] Compared with the prior art, the present invention has the following technical effects:

[0038] The present invention can simulate and calculate the gearbox shifting process under any design parameters by establishing a detailed and scientific simulation model, and can calculate the severity of the secondary shift ring under the design parameters of the asymmetric eccentric locking angle, and the result is accurate and reliable. Calculations are performed for different transmission design parameters and the calculation results are compared. The design parameters with the best simulation calculation results are selected to improve the transmission design, which not only greatly reduces the R&D time cost, but also allows a more comprehensive comparison of more different design parameters, greatly improving the improvement effect. DETAILED DESCRIPTION

[0039] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments, which should not be construed as limiting the technical solution.

[0040] Embodiment: A simulation model of a 6-speed mechanical gearbox product is established, with the goal of optimizing the severity of the secondary shift ring when shifting from 2nd gear to 3rd gear. Simulations are performed for different improvement parameters, and the simulation results are compared. The optimal improved design parameters are selected for sample trial production and test verification. The number of cone surfaces of this box-type synchronizer is set to: double, double, double, single, single; the synchronizer size is based on the synchronizer model size of the actual batch packing; the improvement parameter is the synchronizer locking angle, and the severity of the secondary shift ring under different locking angle settings is compared. The optimal locking angle design parameters of the secondary shift ring are selected to improve the product. The speed of the first shaft for upshifting is set to 2100rpm, and the speed of the first shaft for downshifting is set to 2100rpm after the downshift is completed. The shift force peak limit is 1200N (consistent with the bench test conditions). According to the above method, the process of shifting from 2nd gear to 3rd gear of the gearbox is simulated and analyzed, and the calculation results are compared to confirm and verify the design scheme. The specific steps are as follows:

[0041] Step 1: Establish a simulation model of the gear shift actuator

[0042] The shift actuator includes a shift rocker arm, a lateral shift lever and a shift fork. Its function is to transmit the shift force and displacement at the shift hand ball to the synchronizer.

[0043] Step 1 includes the following sub-steps:

[0044] Step 11: Build a model for the shift rocker arm to drive the horizontal shift lever and shift knob to rotate

[0045] In this model, the shift rocker arm drives the lateral shift rod. The speed difference between the rocker arm and the hand ball causes the deformation of the rocker arm to generate torque. The rotation of the rocker arm drives the lateral shift rod to rotate. Confirm the length of the shift rocker arm and the length of the inner shift head.

[0046] Step 12, establish a model for the shift fork shaft and the shift fork to move through the shift head when the lateral shift lever rotates. This includes the force model of the shift fork shaft and the shift fork, and the kinematic model of the shift fork shaft and the shift fork after being subjected to force; the rocker arm rotates to drive the inner shift head to rotate (fixed connection), the inner shift head rotates to produce relative displacement with the guide block, the guide block deforms and is subjected to force, and drives the shift fork shaft and the shift fork to move (fixed connection).

[0047] Step 13: Establish a model in which the shift fork moves to drive the synchronizer sleeve to shift gears

[0048] In this model, the relative displacement between the shift fork and the synchronizer sleeve causes deformation, which causes the synchronizer sleeve to be subjected to the shift force. When the synchronizer sleeve is displaced by the shift force, it is also subjected to the resistance generated inside the synchronizer during the synchronization process. The shift force overcomes the resistance and pushes the sleeve forward; the resistance during the shift is fed back to the shift fork, and the movement direction of the sleeve is different when shifting different gears. The dead zone module is used in this model to simulate the fit clearance between the parts during force and motion transmission. Only when the relative displacement exceeds the fit clearance will the parts contact to generate deformation and force. The value of the dead zone module is determined by the difference between the width of the shift fork slot and the width of the shift fork fork foot.

[0049] Step 2: Establish a torque transmission simulation model of rotating parts

[0050] Rotating parts are divided into external rotating parts of the transmission and internal rotating parts of the transmission. The external rotating parts of the transmission include the clutch driven plate and the constant mesh gear pair. The internal rotating parts of the transmission include the first shaft, the second shaft, the second shaft gear, the intermediate shaft assembly, the reverse gear intermediate gear and the synchronizer. The path of torque transmission of rotating parts: the rotation of the first shaft is transmitted to the intermediate shaft through the constant mesh gear pair, the intermediate shaft is transmitted to the second shaft gear through the corresponding gear pair, and the second shaft gear meshes with the second shaft through the synchronizer to drive the second shaft to rotate.

[0051] Step 2 specifically includes the following sub-steps:

[0052] Step 21, establish a model of the external rotating parts of the transmission. The clutch driven plate is subjected to the torque transmitted by the engine. Since the clutch is in a disconnected state during the shifting process, the torque transmitted by the engine is set to 0Nm. The clutch driven plate is also subjected to the torque inside the transmission. Establish a simulation model of the clutch driven plate. Among them, the clutch rotates after being subjected to the torque, and the clutch and the transmission rotate relative to each other;

[0053] Step 22, building a model of the internal rotating parts of the transmission.

[0054] Establish a model in which one shaft rotates due to torque, a simulation model in which one shaft transmits torque to the intermediate shaft assembly through constant mesh gears, a gear transmission model for each gear of the two shafts, and a reverse gear transmission model.

[0055] In the torque transmission simulation model, the principle of the torque transmission model between rotating parts is as follows: a. The relative rotation angle difference generates torque (T = k*θ, T: torque (Nm); k: stiffness coefficient (Nm / rad); θ: relative rotation angle (rad)). The stiffness coefficient is calculated from the stiffness of the two meshing teeth. The formula is as follows: K equiv =1 / (1 / K1+1 / K2); b. Torque causes the torqued part to rotate (dω / dt=T / I, dω / dt: angular acceleration (rad / s 2 ); T: torque (Nm); I: moment of inertia (kg*m 2 )), the rotation is transmitted. The "backlash" module is similar to the dead zone module, which is used to simulate the backlash of gear meshing. When the meshing surface is converted, the tooth surface deformation transmission torque will only be generated when the relative displacement between the meshing teeth is greater than the gear meshing backlash value;

[0056] Step 23, establishing a gear transmission model, including: a force model: the gear pair rotates relatively, the tooth surface is deformed by force, the deformation generates force, and the tooth surface generates torque by force; a motion model: the gear is subjected to torque and overcomes resistance to generate rotation.

[0057] Step 3: Build a synchronizer simulation model

[0058] The synchronizer includes synchronizer gear hub, synchronizer sliding gear sleeve, synchronizer combined gear ring and synchronizer friction ring. Each part cooperates with each other to realize the gear shifting function of the transmission. Its structure is relatively complex, and a synchronizer simulation model needs to be established according to the working process of each part during gear shifting.

[0059] Step 3 specifically includes the following sub-steps:

[0060] Step 31, establishing a synchronizer simulation model according to actual synchronizer design parameters, including the locking angle between the sleeve and the outer friction ring, the locking radius, the sleeve inverted cone angle, the friction cone surface angle, the friction cone surface friction coefficient, the friction cone surface radius, the compression spring stiffness, and the pin groove shape.

[0061] The synchronizer simulation model is encapsulated as an independent module, whose input is the rotation speed of the rotating parts at both ends of the synchronizer and the displacement of the sliding sleeve, and its output is the force fed back to the sliding sleeve during the synchronization process and the synchronous torque exerted on the rotating parts at both ends of the synchronizer.

[0062] After the synchronizer sleeve is subjected to the fork force, it will be displaced in two directions. One is the axial displacement to extend the shift position. The axial displacement is mainly affected by the return resistance when the synchronizer is working. The other is the torsional displacement (tilt) of the sleeve caused by the side clearance of the spline fit between the synchronizer sleeve and the synchronizer gear hub. The torsional displacement of the sleeve increases the friction resistance during the movement process.

[0063] The existing synchronizer models are relatively simple, especially in the locking process, the shifting ring force and locking force are calculated only based on the locking angle and trigonometric functions. This simple model cannot simulate the situation of asymmetric locking angles, let alone the situation where the locking angles of the sleeve and the friction ring are different. Since this simulation model is a combined model of locking teeth, it can simulate any locking angle, eccentricity, and different locking angles. When the locking angle is an asymmetric eccentric design and the locking angles of the sleeve and the friction ring are different, the tooth surface contact position during locking will affect the size of the locking angle. Different locking surfaces used for shifting up and down will also result in different locking angles. Especially during the secondary shifting ring, the asymmetric locking angle will produce secondary shifting rings of different severity according to their collision position, which is also the most important means to optimize the severity of the secondary shifting ring.

[0064] Step 32, in addition to the design parameters of the synchronizer, different synchronizer structures will also have great differences in the synchronization process, affecting the simulation calculation process. The main types of synchronizer structures are: single-cone synchronizer, double-cone coupled synchronizer, double-cone uncoupled synchronizer, three-cone synchronizer, etc. Different types of synchronizers have great differences in the calculation of friction torque involved in the simulation calculation process. All types of synchronizer calculation models are integrated in the synchronizer module and numbered. When using, you only need to call the corresponding calculation model according to the corresponding synchronizer number.

[0065] Step 33, all models are combined according to the internal mechanism logic of the transmission to form a transmission shift calculation simulation model, and a main shift condition setting interface is reserved for quickly adjusting input parameters.

[0066] Step 4: Set the gear shift conditions and start the transmission shift simulation calculation

[0067] Step 4 specifically includes the following sub-steps:

[0068] Step 41, set internal parameters: a. Synchronizer type (single cone, double cone, triple cone) internal parts size parameters (diameter, left locking angle, right locking angle, eccentricity, cone angle, friction coefficient, etc.); b. Synchronizer internal parts size parameters (diameter, left locking angle, right locking angle, eccentricity, cone angle, friction coefficient, etc.); c. Parameters of other rotating parts such as gears (contact stiffness, center distance, inertia, etc.).

[0069] The 3rd gear synchronizer type of the target transmission is a double-cone non-coupled synchronizer. Enter the corresponding number to call the calculation model of this type of synchronizer; set the parameters of the synchronizer calculation model according to the actual synchronizer design parameters.

[0070] Step 42, setting external parameters: the rotation speed of one shaft during gear shifting, the initial gear shifting speed of the gear shifting knob, the type of gear shifting (static gear shifting, dynamic gear shifting), the gear position of the gear shifting, the maximum peak force limit during gear shifting, etc.

[0071] The input parameters should be kept consistent with the bench test parameters as much as possible, so as to facilitate subsequent verification on the test bench after trial production of the actual product;

[0072] Step 43, simulation analysis and calculation are started, the shift hand ball starts to move at the set speed, drives the outer shift rocker arm to swing, drives the lateral shift lever to rotate, drives the shift fork to move through the shift head, and drives the synchronizer sleeve to move, and starts shifting. After the pre-synchronization, synchronization, primary shift ring, idle travel, secondary shift ring and other stages, the shift is completed.

[0073] Please do not change the model and parameters during the model running process. The first simulation running time is relatively long. An oscilloscope is set in the model to observe the changes of various target parameters over time during the simulation process.

[0074] Step 5: Output simulation results and data processing analysis

[0075] Step 5 specifically includes the following sub-steps:

[0076] Step 51, after the calculation is completed, the calculation result curve is retrieved. The main output results are the curve of the change of the shift force over time, the curve of the change of the shift displacement over time, the curve of the change of the first axis speed over time, and the curve of the change of the second axis torque over time, which are consistent with the experimental bench. The curve can also be exported as a data table for secondary analysis and calculation in subsequent research of the present invention;

[0077] Step 52, analyze the curve of the change of the shift force over time, and obtain the severity of the secondary shift ring in this shift simulation. Adjust the locking angle of the sliding sleeve and the outer friction ring in the input parameters, re-simulate and calculate, and make a comprehensive comparison of the calculation results, select the optimal design parameters, and complete the optimization and improvement of the locking angle on the secondary shift ring.

[0078] The output simulation result data is the same as the bench test output data, mainly the change curve of shift force over time, the change curve of shift displacement over time, the change curve of axis 1 speed over time, and the change curve of axis 2 torque over time. The output result curve can also be exported as a data table.

Claims

1. A simulation analysis method for dynamic shifting of a mechanical transmission, characterized in that: The steps include: Step 1: Establish a simulation model of a gear shift actuator, wherein the gear shift actuator includes a gear shift rocker arm, a transverse gear shift rod and a shift fork; Step 2: Establish a torque transmission simulation model of rotating parts, wherein the rotating parts are divided into external rotating parts of the transmission and internal rotating parts of the transmission. The external rotating parts of the transmission include the clutch driven plate and the constant meshing gear pair, and the internal rotating parts of the transmission include the first shaft, the second shaft, the second shaft gear, the intermediate shaft assembly, the reverse gear intermediate gear and the synchronizer; Step 3: Establish a synchronizer simulation model, wherein the synchronizer includes a synchronizer gear hub, a synchronizer sliding gear sleeve, a synchronizer combined gear ring and a synchronizer friction ring; Step 4: Set the shifting conditions and start the transmission shifting simulation calculation, including setting internal parameters, setting external parameters and simulation analysis calculation; Step 5: Output simulation results and data processing and analysis.

2. The simulation analysis method for dynamic shifting of a mechanical transmission according to claim 1, characterized in that: Step 1 includes the following sub-steps: Step 11: Build a model for the shift rocker arm to drive the horizontal shift lever and shift knob to rotate Among them, the shift rocker arm drives the lateral shift lever, and the speed difference between the rocker arm and the hand ball causes the deformation of the rocker arm to generate torque. The rotation of the rocker arm drives the lateral shift lever to rotate; confirm the length of the shift rocker arm and the length of the inner shift head; Step 12, establish a model for the movement of the shift fork shaft and the shift fork through the shift head when the lateral shift lever rotates; including a force model of the shift fork shaft and the shift fork, and a kinematic model of the shift fork shaft and the shift fork after being subjected to force; the rotation of the rocker arm drives the rotation of the inner shift head, the rotation of the inner shift head produces a relative displacement with the guide block, the guide block is deformed and subjected to force, and drives the shift fork shaft and the shift fork to move. Step 13: Establish a model in which the shift fork moves to drive the synchronizer sleeve to shift gears In this model, the relative displacement between the shift fork and the synchronizer sleeve produces deformation, causing the synchronizer sleeve to be subjected to the shift force. When the synchronizer sleeve is displaced by the shift force, it is also subjected to the resistance generated inside the synchronizer during the synchronization process. The shift force overcomes the resistance and pushes the sleeve forward; the resistance during shifting is fed back to the shift fork, and the movement direction of the sleeve is different when changing to different gears.

3. The simulation analysis method for dynamic shifting of a mechanical transmission according to claim 1, characterized in that: Step 2 specifically includes the following sub-steps: Step 21, establishing a model of the external rotating parts of the transmission, the clutch driven plate is subjected to the torque transmitted by the engine, and since the clutch is in a disconnected state during the gear shifting process, the torque transmitted by the engine is set to 0Nm, and the clutch driven plate is also subjected to the torque inside the transmission, and a simulation model of the clutch driven plate is established; wherein, the clutch rotates after being subjected to the torque, and the clutch and the transmission rotate relative to each other; Step 22, establishing a model of the internal rotating parts of the transmission, establishing a model of a shaft rotating due to torque, a simulation model of a shaft transmitting torque to an intermediate shaft assembly through a constant mesh gear, a gear transmission model of each gear of the second shaft, and a reverse gear transmission model; Step 23, establishing a gear transmission model, including: a force model: the gear pair rotates relatively, the tooth surface is deformed by force, the deformation generates force, and the tooth surface generates torque by force; a motion model: the gear is subjected to torque and overcomes resistance to generate rotation. Step 3: Build a synchronizer simulation model The synchronizer includes a synchronizer gear hub, a synchronizer sliding gear sleeve, a synchronizer combined gear ring, and a synchronizer friction ring.

4. The simulation analysis method for dynamic shifting of a mechanical transmission according to claim 1, characterized in that: Step 3 specifically includes the following sub-steps: Step 31, establishing a synchronizer simulation model according to actual synchronizer design parameters, including a locking angle between the sleeve and the outer friction ring, a locking radius, a sleeve inverted cone angle, a friction cone surface angle, a friction cone surface friction coefficient, a friction cone surface radius, a compression spring stiffness, and a pin groove shape; The synchronizer simulation model is encapsulated as an independent module, whose input is the rotation speed of the rotating parts at both ends of the synchronizer and the displacement of the sliding sleeve, and the output is the force fed back to the sliding sleeve during the synchronization process and the synchronous torque exerted on the rotating parts at both ends of the synchronizer; After the synchronizer sleeve is subjected to the fork force, it will be displaced in two directions. One is the axial displacement to extend the shift position. The axial displacement is mainly affected by the return resistance when the synchronizer is working. The other is the torsional displacement of the sleeve caused by the side clearance of the spline fit between the synchronizer sleeve and the synchronizer gear hub. The torsional displacement of the sleeve increases the friction resistance during the movement process. Step 32, the main types of synchronizer structures are: single-cone synchronizer, double-cone coupled synchronizer, double-cone uncoupled synchronizer, and three-cone synchronizer; all types of synchronizer calculation models are integrated in the synchronizer module and numbered; Step 33, all models are combined according to the internal mechanism logic of the transmission to form a transmission shift calculation simulation model, and a main shift condition setting interface is reserved for quickly adjusting input parameters.

5. The simulation analysis method for dynamic shifting of a mechanical transmission according to claim 1, characterized in that: Step 4 specifically includes the following sub-steps: Step 41, setting internal parameters: a. synchronizer type internal parts size parameters; b. synchronizer internal parts size parameters; c. gears and other rotating parts parameters; Step 42, setting external parameters: a shaft speed during gear shifting, an initial gear shifting speed of a gear shifting hand ball, a gear shifting type, a gear shifting position, and a maximum peak force limit during gear shifting; Step 43, start simulation analysis and calculation, the shift hand ball starts to move at the set speed, drives the outer shift rocker arm to swing, drives the lateral shift lever to rotate, drives the shift fork to move through the shift head, and drives the synchronizer sleeve to move, and starts shifting; after pre-synchronization, synchronization, primary shift ring, idle travel, secondary shift ring and other stages, the shift is completed.

6. The simulation analysis method for dynamic shifting of a mechanical transmission according to claim 1, characterized in that: Step 5 specifically includes the following sub-steps: Step 51, after the calculation is completed, the calculation result curve is retrieved, and the main output results are the curve of the change of the shift force over time, the curve of the change of the shift displacement over time, the curve of the change of the first axis speed over time, and the curve of the change of the second axis torque over time, which are consistent with the experimental bench; Step 52, analyze the curve of the change of the shift force over time, and obtain the severity of the secondary shift ring in this shift simulation; adjust the locking angle of the sliding sleeve and the outer friction ring in the input parameters, re-simulate the calculation, and make a comprehensive comparison of the calculation results, select the optimal design parameters, and complete the optimization improvement of the locking angle on the secondary shift ring.