Method for improving reliability of hydraulic torque converter based on engine excitation

Abstract

The invention belongs to the technical field of vehicle transmission, and particularly discloses a hydraulic torque converter reliability improving method based on engine excitation, which comprises the following steps: collecting engine cylinder pressure and crank angle data, and calculating a time domain excitation torque transmitted to a hydraulic torque converter by an engine; fourier transform is carried out to obtain excitation amplitudes of all orders in a frequency domain; establishing a three-degree-of-freedom concentrated mass model, and calculating an angular acceleration response and an angular acceleration RMS value of an output shaft of the hydraulic torque converter by taking excitation of each order as input; quantitative evaluation is carried out through a preset vibration impact grade; time domain and frequency domain loads are applied to key parts of the hydraulic torque converter for finite element simulation, and checking and optimization of strength, dynamics and fatigue life are completed. According to the method, the quantitative prediction of the vibration impact of the transmission system and the accurate design of the reliability of key components are realized from the real excitation load, and the development efficiency and the product reliability are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of vehicle transmission technology, and specifically relates to a method for improving the reliability of a hydraulic torque converter based on engine excitation. Background Technology

[0002] As a core component of a vehicle's powertrain, the reliability of the torque converter directly impacts the vehicle's NVH performance and durability. Traditional design and reliability evaluation methods typically use the engine's maximum torque and an empirical safety factor as the ultimate load input for the torque converter. This method is primarily based on static strength or quasi-static assumptions, simplifying the load to a constant or slowly varying threshold, without deeply considering the torque excitation and dynamic impact characteristics with rich frequency components generated during actual engine operation. Based on this simplified load, strength checks and design iterations were performed on key components of the torque converter, such as the welded nut, torsional damper, and spline.

[0003] However, because the input load fails to accurately reflect the time-domain fluctuations and frequency-domain distribution characteristics of the engine excitation, there are discrepancies between its reliability assessment and structural optimization and actual operating conditions. This often necessitates multiple design, verification, and testing cycles to optimize design reliability, significantly lengthening the product development cycle and increasing development costs. Furthermore, it may lead to insufficient identification of potential vibration fatigue risks, resulting in inadequate reliability assessments and jeopardizing the long-term durability of the product under complex excitation. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects in the prior art and provide a method for improving the reliability of hydraulic torque converters based on engine excitation.

[0005] This invention provides a method for improving the reliability of a hydraulic torque converter based on engine excitation, comprising the following steps: Obtain the CAD geometric parameters of the target engine, as well as the in-cylinder gas pressure data and crankshaft angle data of the target engine under full throttle conditions; Calculate the time-domain excitation torque transmitted from the piston through the connecting rod assembly to the flexible disc on the crankshaft connected to the hydraulic torque converter. The time-domain excitation torque is subjected to a fast Fourier transform to decompose it into the excitation torque amplitude of each order at different engine speeds. A three-degree-of-freedom lumped mass model of the engine, hydraulic torque converter, and transmission chain is established using the lumped mass method. The excitation torque amplitude is used as the excitation input to the three-degree-of-freedom model to calculate the angular acceleration of the hydraulic torque converter output shaft under each order of excitation. The sum of squares and the square root of each order of angular acceleration are combined to obtain the RMS value of the hydraulic torque converter output shaft angular acceleration under the specified working condition. The calculated angular acceleration RMS value is compared with the preset vibration and shock level threshold to evaluate the vibration and shock level of the system. Using the time-domain excitation torque and the amplitude of each order of excitation torque as load input, finite element simulation is performed on the key components of the hydraulic torque converter to complete the verification of strength, stiffness and fatigue life and the optimization design of geometric parameters.

[0006] A further approach involves calculating the time-domain excitation torque using the following steps: Calculate the total thrust on the piston of a single cylinder: ; ; ; ; Calculate the connecting rod angle and the tangential force acting on the crank: ; ; Calculate the instantaneous torque of a single cylinder: ； Then the first The instantaneous torque curve of the cylinder is ; Based on the number of engine cylinders, firing order, and phase difference between cylinders, the instantaneous torques of each cylinder are superimposed to obtain the engine's time-domain excitation torque, which is calculated using time... Function with independent variable ; in, The thrust exerted on the piston by the gas inside the cylinder. For crank angle, For the linkage swing angle, For the connecting rod thrust, The tangential force acting on the crank. This is the thrust of the gas inside the cylinder on the piston. For reciprocating inertial force, For reciprocating quality, For piston displacement, For piston acceleration, The crankshaft angular velocity, The crank-connecting rod ratio, For crank, It is a connecting rod.

[0007] A further embodiment includes the following steps in the calculation process of the time-domain excitation torque: Based on the engine's firing order and firing interval angle, calculate the crankshaft rotation phase difference of each cylinder relative to the top dead center of the first cylinder. ,in This refers to the cylinder number, and the phase difference of the first cylinder. ; The instantaneous torque curves of each cylinder At the same crankshaft angle Adding the results together, we obtain the engine's time-domain excitation torque as a function of the crankshaft angle: ; in, This refers to the number of engine cylinders. Based on engine instantaneous speed With time Relationship ,Will Convert to time Function with independent variable .

[0008] A further solution is that the calculation process for the excitation torque amplitude at different engine speeds at each order is as follows: For the... Perform a fast Fourier transform to By transforming from the time domain to the frequency domain, the excitation torque amplitudes of each order at different engine speeds are obtained. .

[0009] A further embodiment is that the three lumped moments of inertia of the three-degree-of-freedom lumped mass model are the equivalent inertia on the engine side, the equivalent inertia on the hydraulic torque converter side, and the equivalent inertia on the transmission side mapped to the output shaft of the hydraulic torque converter; the stiffness and damping parameters of the three-degree-of-freedom lumped mass model include the connection stiffness and damping between the engine and the hydraulic torque converter, and the connection stiffness and damping between the hydraulic torque converter and the transmission.

[0010] A further approach is to calculate the angular acceleration as follows: Calculate the engine angular velocity: ; Calculate the first Order excitation frequency: ; Calculate the first Order excitation angular velocity: ; Calculate the transfer amplitude function: ; Calculate the first Angular acceleration of order: ; in, The engine angular velocity, For the first Order excitation angular velocity, For the first Order excitation frequency, To pass the amplitude function, For the equivalent moment of inertia, For equivalent torsional stiffness, This is the equivalent damping coefficient. For the first The amplitude of the excitation torque of the order. For the first Order angular acceleration.

[0011] A further solution is that the formula for calculating the angular acceleration RMS value is: ,in, It is the number of orders involved in the calculation. No. The magnitude of the angular acceleration of the order. It is the root mean square value of angular acceleration.

[0012] A further approach is to divide the preset vibration impact level threshold according to the range of angular acceleration RMS values: 10-100 rad / s². 2 Class A, 100-300 rad / s 2 Class B, 300-500 rad / s 2 Class C, 500-2000 rad / s 2 Grade D is used to quantitatively evaluate the matching performance and vibration and shock performance of hydraulic torque converters in transmission systems.

[0013] A further solution is to perform the following optimization decision based on the vibration and shock level at which the angular acceleration RMS value is located when the vibration and shock level does not meet the preset requirements or the component reliability evaluation fails: When the evaluation result is Grade A, no optimization or adjustment is required; When the evaluation result is B or C, selective optimization is performed based on the type of vehicle and the specific requirements of the OEM. For example, passenger cars require a speed of less than 250 rad / s. 2 The measures include adjusting the torsional stiffness of the hydraulic torque converter torsional damper or the turbine inertia, specifically by adjusting the spring stiffness, adding nested springs, etc., to change the natural frequency of the transmission system and avoid the engine excitation frequency. When the evaluation result is Grade D, it is determined that the current hydraulic torque converter is not properly matched with the transmission system, and the hydraulic torque converter model needs to be replaced or the matching design needs to be redesigned.

[0014] A further approach involves conducting finite element simulations of key components of the hydraulic torque converter, including: The engine time-domain loads at different engine speeds and the excitation loads of each order are applied to the finite element models of the hydraulic torque converter's shroud, pump housing, turbine, welded nut, spline, damper riveting structure, turbine riveting structure, spring, and thin-walled sheet metal parts of the damper. Through static analysis, the thickness and fillet radius of each component are optimized to control the working stress level; and the welding strength of the welded nut connecting the cover wheel and the engine, the spline strength of the wheel hub, the riveting strength of the shock absorber, the riveting strength of the turbine, the spring compression state, and the torsional strength of the thin-walled sheet metal parts of the shock absorber are checked and the structure is strengthened. Optimize the layout of reinforcing ribs, hole positions, or number of claw teeth in components through dynamic analysis; By optimizing the above geometric parameters through fatigue analysis, the predicted fatigue life of the components can be improved. The optimized design is then verified through bench or vehicle testing according to the load spectrum to complete the design closed loop.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention calculates the time-domain excitation torque transmitted to the flexible disk of the hydraulic torque converter by collecting real-time data such as in-cylinder gas pressure and crankshaft angle. Then, it decomposes this time-domain load into excitation torque amplitudes of different orders at different engine speeds using a Fast Fourier Transform, thus obtaining an excitation with frequency attributes. By introducing complete time-domain and frequency-domain information of the engine excitation into the hydraulic torque converter design stage, and performing simulations based on real loads, it avoids the problem of design deviating from actual operating conditions.

[0016] This invention is based on a three-degree-of-freedom lumped mass model. It takes the excitation torque of each order of the engine as input, analyzes and calculates the angular acceleration of the output shaft of the hydraulic torque converter, and further synthesizes the root mean square value of the angular acceleration. By setting a vibration and shock level threshold, it realizes an objective and quantitative graded evaluation of the vibration level of the transmission system. Designers can adjust the stiffness, damping or inertia parameters of the shock absorber according to the evaluation results, thereby improving the efficiency of NVH performance development.

[0017] This invention applies time-domain excitation torque and excitation load spectra of various orders directly to the finite element models of key components such as the shroud, pump casing, turbine, welded nut, and spline, enabling targeted strength and fatigue simulation analysis. Time-domain loads reflect the actual fluctuation history of the torque, suitable for evaluating high-cycle fatigue characteristics; while frequency-domain loads facilitate the identification of fatigue risks caused by resonance. Combining static analysis to optimize local stress concentration and dynamic analysis to avoid excitation frequencies forms a complete fatigue design process. Attached Figure Description

[0018] The following figures are for illustrative purposes only and are not intended to limit the scope of the invention, wherein: Figure 1 Flowchart of the optimized method of this invention; Figure 2 Schematic diagram of the overall deformation results (from different perspectives) under the locked-down condition; Figure 3 Schematic diagram of the overall equivalent stress results (from different perspectives) under locked conditions; Figure 4 : Schematic diagram of overall stress results under locked conditions; where a is the overall maximum principal stress, b is the external tooth root stress, c is the stiffener root stress, d is the limit window stress, e is the rivet hole stress, and f is the cage turbine riveting area stress.

[0019] Figure 5 Schematic diagram of the overall deformation results under hydraulic conditions; Figure 6 : Schematic diagram of stress results under hydraulic conditions; where a is the overall equivalent stress, b is the overall maximum principal stress, c is the stress at the root of the stiffener, and d is the stress in the cage turbine riveting area. Detailed Implementation

[0020] To make the objectives, technical solutions, design methods, and advantages of this invention clearer, specific embodiments are provided for further detailed explanation. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0021] This invention provides a method for improving the reliability of a hydraulic torque converter based on engine excitation, comprising the following steps: Step 1: For the target engine, obtain CAD geometric parameters such as cylinder bore, stroke, connecting rod length, crank radius, and reciprocating mass. Through engine bench testing, under full throttle conditions, simultaneously acquire high-precision in-cylinder gas pressure data and crankshaft angle data to calculate the engine's time-domain excitation torque; specifically, for a single cylinder, calculate the thrust of the in-cylinder gas on the piston based on the measured cylinder pressure. Calculate the reciprocating inertial force based on the geometry and kinematics of the crank and connecting rod. The two combined yield the total piston thrust. Solving for the link swing angle using geometric relationships Then, the tangential force acting on the crank pin is calculated. The final instantaneous torque of a single cylinder is obtained. According to the engine's firing order and the phase difference between each cylinder The instantaneous torque curves of all cylinders By superimposing these functions in the crankshaft rotation domain, the overall time-domain excitation torque function of the engine is obtained. Combined with engine instantaneous speed Turning domain function Converted into the final time-domain excitation torque with time as the independent variable. .

[0022] The calculation process is as follows: Calculate the total thrust on the piston of a single cylinder: ; ; ; ; Calculate the connecting rod angle and the tangential force acting on the crank: ; ; Calculate the instantaneous torque of a single cylinder: ； Then the first The instantaneous torque curve of the cylinder is ; Based on the number of engine cylinders, firing order, and phase difference between cylinders, the instantaneous torques of each cylinder are superimposed to obtain the engine's time-domain excitation torque, which is calculated using time... Function with independent variable ; in, The thrust exerted on the piston by the gas inside the cylinder. For crank angle, For the linkage swing angle, For the connecting rod thrust, The tangential force acting on the crank. This is the thrust of the gas inside the cylinder on the piston. For reciprocating inertial force, For reciprocating quality, For piston displacement, For piston acceleration, The crankshaft angular velocity, The crank-connecting rod ratio, For crank, It is a connecting rod; Based on the engine's firing order and firing interval angle, calculate the crankshaft rotation phase difference of each cylinder relative to the top dead center of the first cylinder. ,in This refers to the cylinder number, and the phase difference of the first cylinder. ; The instantaneous torque curves of each cylinder At the same crankshaft angle Adding the results together, we obtain the engine's time-domain excitation torque as a function of the crankshaft angle: ; in, This refers to the number of engine cylinders. Based on engine instantaneous speed With time Relationship ,Will Convert to time Function with independent variable .

[0023] Step 2: Calculate the time-domain excitation torque By performing a fast Fourier transform, the excitation torque amplitude at different engine speeds and for each order is obtained. ; A lumped mass model of torsional vibration of the engine-torque converter-transmission transmission chain with three degrees of freedom is established using the lumped mass method. The three moments of inertia in this model represent the equivalent inertia on the engine side. Equivalent inertia of hydraulic torque converter pump impeller and housing And the equivalent inertia on the transmission side mapped to the torque converter output shaft. Stiffness and damping parameters in the model , , , These correspond to the connection characteristics between the engine and the torque converter, and between the torque converter and the transmission, respectively. , This represents the characteristics of the torsional damper inside the hydraulic torque converter.

[0024] Step 3: Calculate the excitation torque amplitudes of each order obtained in step 2. As an excitation, the input is fed into the established three-degree-of-freedom lumped mass model to calculate the angular acceleration of the hydraulic torque converter output shaft under each order of excitation. The calculation process includes: Calculate the engine angular velocity: ; Calculate the first Order excitation frequency: ; Calculate the first Order excitation angular velocity: ; Calculate the transfer amplitude function: ; Calculate the first Angular acceleration of order: ; in, The engine angular velocity, For the first Order excitation angular velocity, For the first Order excitation frequency, To pass the amplitude function, For the equivalent moment of inertia, For equivalent torsional stiffness, This is the equivalent damping coefficient. For the first The amplitude of the excitation torque of the order. For the first Order angular acceleration.

[0025] The angular acceleration responses of all orders of interest are synthesized, and their root mean square values ​​are calculated. ,in, It is the number of orders involved in the calculation. No. The magnitude of the angular acceleration of the order. It is the root mean square value of angular acceleration. Compared with the preset vibration and shock level threshold (10-100 rad / s) 2 Class A, 100-300 rad / s 2 Class B, 300-500 rad / s 2 Class C, 500-2000 rad / s 2 By comparing it with Class D, an objective and quantitative evaluation of the overall vibration and impact level of the transmission system under the current configuration can be made, realizing a rapid diagnosis of the matching between the hydraulic torque converter and the transmission system.

[0026] Step 4: Apply time-domain excitation torque and the amplitude of excitation torque at each order As a load input, it is applied to the finite element models of components such as the hydraulic torque converter's impeller, pump housing, turbine, welded nuts, splines, damper riveting points, and springs. Based on this load, the following simulation analysis is performed: The geometric parameters of key components are optimized through static analysis. Specifically, this includes checking the stress level of welded nuts, splines, and riveted parts under maximum instantaneous load, and ensuring static strength safety by optimizing thickness, fillet radius, etc.

[0027] The structural parameters of key components are optimized through dynamic analysis. Specifically, this includes obtaining the natural frequencies and mode shapes of key components, and adjusting the layout of reinforcing ribs, hole positions, number of claw teeth, or adding centrifugal pendulums to ensure that their main modal frequencies avoid the main excitation order frequencies of the engine, thus preventing resonance.

[0028] Fatigue analysis is used to optimize the geometric and structural parameters, thereby improving the predicted fatigue life of the components. In this embodiment, the left cage of a certain type of high-torsional vibration damper is used as an example for static analysis and optimization. The specific implementation process is as follows: Step 4.1: Based on the torque transmission path of the vehicle's drivetrain, determine the torque distribution borne by the left cage under locked and hydraulic conditions: Locking condition: The external teeth bear a spring driving torque of 400 Nm, the limit pin driving torque of 250 Nm, the rivet reverse action torque of 200 Nm, and the stiffening plate bears an inner ring spring reverse torque of 300 Nm. Hydraulic operation: The stiffeners bear a torque of 600 Nm from the inner ring spring, and the turbine transmits a torque of 600 Nm; The above load is used as a static torque input to ensure static strength safety; Step 4.2: Use shell elements to build the finite element model of the left cage with a mesh size of 0.5 mm. Local refinement to 0.2 mm is performed on key areas such as tooth root, stiffener root, and limiting window. The material selected is SAPH440 with an elastic modulus of 200 GPa and a yield strength of 305 MPa.

[0029] Step 4.3: Apply the above-mentioned working condition loads to the corresponding positions, perform static strength simulation analysis, and obtain the stress and deformation distribution.

[0030] Under interlocking conditions, such as Figure 2 As shown, the outer ring teeth of the left cage exhibit the largest deformation, with a maximum value of 0.225 mm; the outer areas of the two limiting windows also show significant deformation, with a deformation value of 0.178 mm. Figure 3-4 As shown in the overall stress cloud diagram, the maximum stress location of the left cage is at the root of the outer tooth. Stress concentration occurs at the root of the outer tooth and the root of the stiffener, with higher stress concentration coefficients at the root of the outer tooth and the outer root of the stiffener. The maximum equivalent stress is 431.21 MPa (root of the outer tooth), and the maximum principal stress is 420.62 MPa (root of the stiffener). The stress concentration coefficient is highest at the root of the outer tooth, with a maximum equivalent stress of 431.21 MPa. The stress at the root varies gradient in the thickness direction, decreasing from the inner edge to the outer edge. Stress concentration occurs on one side of the limiting window, with a maximum equivalent stress of 183.66 MPa. The stress also varies gradient in the thickness direction, decreasing from the outer edge to the inner edge. The maximum equivalent stress at the riveting hole between the left and right cages is 81.55 MPa. The stress concentration factor at the outer root of the stiffener is relatively high, with a maximum equivalent stress of 412.56 MPa. The stress varies in gradient along the thickness direction, decreasing from the outer side to the inner side. The stress at the inner root of the stiffener is 147.3 MPa.

[0031] Under hydraulic conditions, such as Figure 5 As shown, the left cage outer tooth exhibits the largest deformation, with a maximum value of 0.285 mm; the outer ring area shows the most significant deformation. Figure 6As shown, the maximum stress location of the left cage is at the root of the inner stiffener. Stress concentration occurs at the root of the stiffener and the root region of the turbine riveting teeth, with a higher stress concentration factor at the root of the stiffener. The maximum equivalent stress is 629.97 MPa, and the maximum principal stress is 637.03 MPa (due to the use of linear elastic material constitutive model, the increase in stress due to plastic deformation after exceeding the yield strength will be slowed down, and the actual stress value is within the range of 305 to 637). The stress concentration factor is high at the root of the inner stiffener, with a maximum equivalent stress of 625.45 MPa, and the stress is concentrated on the outer edge of the root of the stiffener. Stress concentration occurs at the root of the outer stiffener, with a maximum equivalent stress of 585.02 MPa, and the stress is concentrated in the middle position of the thickness direction at the root of the stiffener. Stress concentration occurs at the root of the turbine riveting teeth of the left cage, with a maximum equivalent stress of 138 MPa.

[0032] Based on the simulation results, the following optimization measures were implemented: the root cleaning transition of the external tooth root was changed to a small torque fillet; the width between the root cleaning of the stiffener plate and the limiting window was increased to improve the local stiffness; and the root of the stiffener plate was rounded for optimization.

[0033] After optimization and re-simulation, the results show that: under the locked condition, the stress at the root of the external tooth is reduced to 264MPa, and the stress at the root of the stiffener is reduced to 164MPa; under the hydraulic condition, the stress at the root of the external tooth is reduced to 15MPa, and the stress at the root of the stiffener is reduced to below 305MPa. The strength of the left cage of the strong torsional vibration damper meets the usage requirements.

[0034] Step 5: Based on the vibration evaluation results, perform hierarchical decision-making and optimization: If the evaluation result is Grade A, it indicates that the vibration level is excellent and no further optimization is needed; If the evaluation result is B or C, and the specific NVH target for the vehicle type is not met (e.g., passenger car requirement <250 rad / s), then... 2 If so, then return to adjust the key parameters in the three-degree-of-freedom model, such as the equivalent stiffness of the hydraulic torque converter torsional damper. With damping Alternatively, adjust the turbine inertia. This can be achieved by changing the system's natural frequency to avoid the engine's primary excitation, and then repeating step 3 to calculate... Until the evaluation meets the standards; If the evaluation result is Grade D, it indicates a severe mismatch between the current hydraulic torque converter and the system, requiring a replacement model or a complete conceptual design. Based on this, if strength or fatigue issues are identified in the component simulation in step 4, the component structure will be optimized. Finally, the optimized system parameters and component geometric design schemes will be used to guide the manufacturing of physical prototypes. Bench tests will then be conducted to verify the results according to the actual load spectrum obtained in step 1, forming a closed-loop design from virtual simulation to physical verification.

[0035] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for improving the reliability of a hydraulic torque converter based on engine excitation, characterized in that, Includes the following steps: Obtain the CAD geometric parameters of the target engine, as well as the in-cylinder gas pressure data and crankshaft angle data of the target engine under full throttle conditions; Calculate the time-domain excitation torque transmitted from the piston through the connecting rod assembly to the flexible disc on the crankshaft connected to the hydraulic torque converter. The time-domain excitation torque is subjected to a fast Fourier transform to decompose it into the excitation torque amplitude of each order at different engine speeds. A three-degree-of-freedom lumped mass model of the engine, hydraulic torque converter, and transmission chain is established using the lumped mass method. The excitation torque amplitude is used as the excitation input to the three-degree-of-freedom model to calculate the angular acceleration of the hydraulic torque converter output shaft under each order of excitation. The sum of squares and the square root of each order of angular acceleration are combined to obtain the RMS value of the hydraulic torque converter output shaft angular acceleration under the specified working condition. The calculated angular acceleration RMS value is compared with the preset vibration and shock level threshold to evaluate the vibration and shock level of the system. Using the time-domain excitation torque and the amplitude of each order of excitation torque as load input, finite element simulation is performed on the key components of the hydraulic torque converter to complete the verification of strength, stiffness and fatigue life and the optimization design of geometric parameters.

2. The method for improving the reliability of a hydraulic torque converter based on engine excitation according to claim 1, characterized in that, The calculation process of the time-domain excitation torque includes the following steps: Calculate the total thrust on the piston of a single cylinder: ； ； ； ； Calculate the connecting rod angle and the tangential force acting on the crank: ； ； Calculate the instantaneous torque of a single cylinder: ； Then the first The instantaneous torque curve of the cylinder is ; Based on the number of engine cylinders, firing order, and phase difference between cylinders, the instantaneous torques of each cylinder are superimposed to obtain the engine's time-domain excitation torque, which is calculated using time... Function with independent variable ; in, The thrust exerted on the piston by the gas inside the cylinder. For crank angle, For the linkage swing angle, For the connecting rod thrust, The tangential force acting on the crank. This is the thrust of the gas inside the cylinder on the piston. For reciprocating inertial force, For reciprocating quality, For piston displacement, For piston acceleration, The crankshaft angular velocity, The crank-connecting rod ratio, For crank, It is a connecting rod.

3. The method for improving the reliability of a hydraulic torque converter based on engine excitation according to claim 1, characterized in that, The calculation process of the time-domain excitation torque also includes: Based on the engine's firing order and firing interval angle, calculate the crankshaft rotation phase difference of each cylinder relative to the top dead center of the first cylinder. ,in This refers to the cylinder number, and the phase difference of the first cylinder. ; The instantaneous torque curves of each cylinder At the same crankshaft angle Adding the results together, we obtain the engine's time-domain excitation torque as a function of the crankshaft angle: ； in, This refers to the number of engine cylinders. Based on engine instantaneous speed With time Relationship ,Will Convert to time Function with independent variable .

4. The method for improving the reliability of a hydraulic torque converter based on engine excitation according to claim 3, characterized in that, The calculation process for the excitation torque amplitude at different engine speeds is as follows: For the... Perform a fast Fourier transform to By transforming from the time domain to the frequency domain, the excitation torque amplitudes of each order at different engine speeds are obtained. .

5. The method for improving the reliability of a hydraulic torque converter based on engine excitation according to claim 4, characterized in that, The three lumped moments of inertia of the three-degree-of-freedom lumped mass model are the equivalent inertia on the engine side, the equivalent inertia on the torque converter side, and the equivalent inertia on the transmission side mapped to the output shaft of the torque converter; the stiffness and damping parameters of the three-degree-of-freedom lumped mass model include the connection stiffness and damping between the engine and the torque converter, and the connection stiffness and damping between the torque converter and the transmission.

6. The method for improving the reliability of a hydraulic torque converter based on engine excitation according to claim 5, characterized in that, The calculation process for the angular acceleration is as follows: Calculate the engine angular velocity: ; Calculate the first Order excitation frequency: ; Calculate the first Order excitation angular velocity: ; Calculate the transfer amplitude function: ; Calculate the first Angular acceleration of order: ; in, The engine angular velocity, For the first Order excitation angular velocity, For the first Order excitation frequency, To pass the amplitude function, For the equivalent moment of inertia, For equivalent torsional stiffness, This is the equivalent damping coefficient. For the first The amplitude of the excitation torque of the order. For the first Order angular acceleration.

7. The method for improving the reliability of a hydraulic torque converter based on engine excitation according to claim 6, characterized in that, The formula for calculating the RMS value of angular acceleration is: ,in, It is the number of orders involved in the calculation. No. The magnitude of the angular acceleration of the order. It is the root mean square value of angular acceleration.

8. The method for improving the reliability of a hydraulic torque converter based on engine excitation according to claim 7, characterized in that, The preset vibration and impact level threshold is divided according to the range of angular acceleration RMS value: 10-100 rad / s 2 Class A, 100-300 rad / s 2 Class B, 300-500 rad / s 2 Class C, 500-2000 rad / s 2 Grade D is used to quantitatively evaluate the matching performance and vibration and shock performance of hydraulic torque converters in transmission systems.

9. The method for improving the reliability of a hydraulic torque converter based on engine excitation according to claim 8, characterized in that, When the vibration and shock level does not meet the preset level requirements, or the component reliability evaluation fails, the following optimization decision is executed based on the vibration and shock level at which the angular acceleration RMS value is located: When the evaluation result is Grade A, no optimization or adjustment is required; When the evaluation result is B or C, the judgment is made according to the specific vibration requirements of the target vehicle: if the evaluation result does not meet the vibration limit requirements of the vehicle type, the equivalent stiffness and equivalent damping of the hydraulic torque converter torsional damper are adjusted or the equivalent moment of inertia of the turbine is adjusted. When the evaluation result is Grade D, it is determined that the current hydraulic torque converter is not properly matched with the transmission system, and the hydraulic torque converter model needs to be replaced or the matching design needs to be redesigned.

10. The method for improving the reliability of a hydraulic torque converter based on engine excitation according to claim 9, characterized in that, Finite element simulation of key components of a hydraulic torque converter includes: The engine time-domain loads at different engine speeds and the excitation loads of each order are applied to the finite element models of key components of the hydraulic torque converter. Optimize the geometric parameters of key components through static analysis; Optimize the structural parameters of key components through dynamic analysis; By optimizing the geometric and structural parameters through fatigue analysis, the predicted fatigue life of the components can be improved. The optimized design was tested under time-domain loads and excitation loads of various orders.

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