Automatic gearbox actuating mechanism parameter optimization design method based on sensitivity analysis and genetic algorithm

Abstract

The invention relates to an automatic gearbox executing mechanism parameter optimization design method based on sensitivity analysis and a genetic algorithm, and belongs to the technical field of engineering machinery design. The method comprises the following steps: establishing dynamical models of an automatic gearbox actuating mechanism considering electromechanical hydraulic characteristics, including dynamical models of a gear pump, a proportional electromagnetic valve and a clutch; utilizing a sensitivity analysis method to explore the influence degree of internal and external parameters on the pressure and efficiency of the hydraulic system, and determining main optimization variables of the hydraulic system; designing a controller to track the pressure of a hydraulic system according to the required oil pressure of each electromagnetic valve and a clutch in a gear shifting control strategy; the gear shifting impact degree and the sliding friction work of a friction pair are used as optimization targets, the gear shifting time is used as a constraint condition, a genetic algorithm is used for optimizing main optimization variables of a hydraulic system within the range allowed by parameters, and gear shifting quality improvement and forward optimization design of an automatic gearbox executing mechanism are completed.

Description

Technical Field

[0001] The invention belongs to the technical field of engineering machinery design, and relates to a parameter optimization method for an automatic transmission for a loader, and specifically to a parameter optimization design method for an automatic transmission actuator based on sensitivity analysis and a genetic algorithm. Background Art

[0002] With the increasing maturity of engineering machinery research and development and production technology and the gradual expansion of application scenarios, the demand for high-end engineering machinery equipment such as loaders has gradually increased. The hydraulic transmission is a key component of high-end mechanical equipment. Its design and optimization process can not only improve the performance and efficiency of the system, improve the consumption of operating energy and production costs, but also improve the reliability and stability of the actuator, and reduce the impact and friction of the system. Therefore, the design and optimization link is the top priority in the development and production of the whole vehicle, and also provides a reference for the research and industrialization of loaders equipped with mechanical automatic transmissions or new energy. At present, the common optimization design methods can be divided into: experimental method, simulation method and intelligent optimization algorithm according to the optimization method. Among them, the experimental method generally selects the best combination parameters by designing a suitable test plan and measuring and analyzing the performance data after different parameter changes. Although the experimental method can select the optimal parameters more intuitively and reliably, it takes a lot of time and resource costs to carry out the test process many times. The simulation method is committed to using professional software to build a physical or mathematical model of the system, and simulate and optimize by continuously adjusting the model parameters. The simulation of the virtual model can reduce the cost consumption in the system design and test process, but the manual parameter adjustment process makes its optimization efficiency low. The optimization method based on intelligent algorithm sets the objective function and boundary conditions and combines advanced intelligent algorithms to efficiently search for the best parameters, but the numerous control and design parameters and their coupling relationships affect the optimization effect. Therefore, it is necessary to comprehensively consider the dynamic response characteristics of the automatic transmission actuator, improve the existing optimization method based on intelligent algorithm, perform sensitivity analysis on the parameters to explore the main optimization variables, and finally achieve the optimal design of the automatic transmission actuator parameters. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide an automatic transmission actuator parameter optimization design method based on sensitivity analysis and genetic algorithm, by analyzing the dynamic response characteristics of the automatic transmission actuator design parameters and control parameters and their influence, and combining the search of genetic algorithm under the set objective function and boundary conditions, to achieve the optimization design of the automatic transmission actuator for loader.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A parameter optimization design method for automatic transmission actuator based on sensitivity analysis and genetic algorithm is proposed. The dynamic model of automatic transmission actuator considering electromechanical and hydraulic characteristics is established, including the dynamic models of key components such as gear pump, proportional solenoid valve and clutch. The dynamic response characteristics of automatic transmission hydraulic system and actuator under different design parameters and control parameters are analyzed. The sensitivity analysis method is used to explore the influence of internal and external parameters on the pressure and efficiency of hydraulic system, and the main optimization variables of hydraulic system are determined. According to the required oil pressure of each solenoid valve and clutch in the shift control strategy, a controller is designed to track the pressure of hydraulic system. The important quality shift shock degree and sliding friction work of friction pair in engineering machinery are taken as optimization targets, and the shift time is taken as constraint condition. The main optimization variables of hydraulic system are optimized within the range allowed by parameters by using genetic algorithm and other intelligent algorithms, so as to complete the shift quality improvement and forward optimization design of automatic transmission actuator.

[0006] Furthermore, a dynamic model of the automatic transmission actuator considering the electromechanical and hydraulic characteristics is established, specifically including: the hydraulic oil is taken out from the oil pool under the action of the mechanical gear pump and passes through the coarse filter and the fine filter, and is distributed to each proportional solenoid valve according to the required oil pressure of each clutch in the shift control strategy; according to the physical parameters of the main oil circuit regulation subsystem and the key components in the actuator, its dynamic simulation HCD model parameters are set;

[0007] The clutch engagement process can be divided into three stages, namely, the friction plate free clearance elimination stage, the sliding friction stage and the pressing stage. Analysis shows that the piston assembly is affected by inertia force, fluid force, spring force, piston sealing ring friction resistance and piston viscous friction resistance, and the dynamic equilibrium equation of the clutch piston assembly is:

[0008]

[0009] Where M L is the mass of the piston and one third of the spring, kg; x L is the piston displacement, m; P L is the internal pressure of the clutch cylinder, Pa; d1 is the outer diameter of the clutch, m; d2 is the inner diameter of the clutch, m; K LS is the return spring stiffness, N / m; x Lo is the initial compression of the spring, m; α is the damping coefficient of the sealing ring; b is the width of the sealing ring, m; B Lc is the viscous damping coefficient, N·s / m;

[0010] When the clutch is disengaged and engaged, the oil cylinder is in the oil discharge and oil filling stages respectively. Considering the compressibility of the oil, the oil volume changes differently during oil filling and oil discharge. Assuming there is no oil leakage, the flow rate Q in the oil filling and oil discharge stages is L They are:

[0011]

[0012] In the formula, C = d 2 / (32μl), where d is the diameter of the throttle hole; μ is the viscosity of the oil; l is the length of the throttle hole; A is the area of ​​the flow cross section of the throttle hole, m 2 ; V L is the initial volume of the oil cylinder, m 3 ; S L is the piston action area, m 2 ;

[0013] The torque transmitted by the clutch is different in the normal engagement state with the gear fixed and during the gear shifting process. The torque transmitted by the clutch under the two different working conditions is:

[0014]

[0015] Where, T c The clutch transmits torque, N·m; T load is the load torque, N·m, i.e. the required torque of the vehicle; the second formula is the torque transmitted by the clutch during the clutch shifting process, n is the number of friction pairs; r is the working radius of the friction plate, m; F LS is the spring force.

[0016] Furthermore, the dynamic response characteristics of the automatic transmission hydraulic system and actuator under different design parameters and control parameters are analyzed, including:

[0017] (1) The influence of the spring parameters of the proportional solenoid valve on the dynamic response characteristics of the hydraulic system pressure: The spring mainly plays the role of adjusting the valve core position, thereby changing the valve port size and finally obtaining the target pressure or target flow. Considering the error in the actual measurement data, the spring stiffness k and the initial spring compression x of the proportional solenoid valve in the hydraulic system are analyzed within a suitable range. o Impact on the dynamic response characteristics of the hydraulic system; As the spring stiffness increases, the dynamic response and stable value of pressure remain almost unchanged, but the response time of the oil pressure is significantly delayed; The impact of the initial compression of the spring on the pressure response is similar to that of the spring stiffness. As the initial compression of the spring increases, the greater the spring force, the dynamic response and stable value of pressure remain almost unchanged, but the response time of the oil pressure is significantly delayed. It can be seen that the initial compression of the spring has a more obvious effect on the hysteresis of the oil pressure of the solenoid valve than the spring stiffness;

[0018] (2) The influence of the valve core mass of the proportional solenoid valve on the dynamic response characteristics of the hydraulic system pressure: The inertia of an object is related to its mass and has an impact on the movement of the object; when the valve core mass increases from 0.015Kg to 0.035Kg, the dynamic response characteristics of the clutch control oil pressure change very little;

[0019] (3) The influence of damping hole size on the dynamic response characteristics of hydraulic system pressure: There are a large number of damping holes in the actual object and schematic diagram of the automatic transmission hydraulic system, which can buffer and suppress the fluctuations of pressure and flow, and play a vital role in the stability and safety of the entire hydraulic system. In general, different damping hole sizes have a certain influence on the dynamic response characteristics of the shift oil pressure. With the increase of the diameter of the damping hole, the system output pressure response tends to become faster, and the larger the diameter, the weaker the trend of faster response, but the pressure fluctuation intensifies. The size of the damping hole at both ends of the solenoid valve mainly affects the response time of the stage of eliminating the free gap of the friction plate, and the size of the damping hole on the right end has a greater impact, and it will also cause pressure fluctuations in the clutch clamping stage; the damping hole size of the clutch actuator mainly affects the time of the clutch clamping stage;

[0020] (4) The influence of piston outer diameter or piston action area on the dynamic response characteristics of hydraulic system pressure: Considering that the piston inner diameter is limited by the automatic transmission shaft, changing the piston action area can only be achieved by changing the clutch outer diameter. p ) on the dynamic response characteristics of the hydraulic system. As the outer diameter of the clutch increases, the oil pressure in the oil chamber decreases, and the pressure response speed slows down; this is mainly because as the outer diameter of the clutch increases, the volume of the oil cylinder chamber increases, the time required to fill the oil chamber becomes longer, and the pressure response also slows down.

[0021] (5) The influence of clutch return spring on the dynamic response characteristics of hydraulic system pressure: The return spring preload includes the return spring stiffness k c and initial compression x c It has a certain influence on the clutch idle stroke and sliding friction stage. The influence of the return spring preload on the dynamic response characteristics of the hydraulic system is analyzed within a reasonable range. The greater the clutch return spring stiffness and initial compression, the greater the corresponding return spring preload, the more delayed the piston movement, and the slower the increase in the cylinder volume, so the pressure value of the hydraulic oil in the oil chamber is greater. It can be seen that the return spring stiffness has a more significant effect on the piston hydraulic oil pressure boost stage relative to the initial compression;

[0022] (6) The influence of clutch piston mass on the dynamic response characteristics of hydraulic system pressure: The influence of clutch piston mass m on the dynamic response characteristics of hydraulic system is analyzed within a reasonable range. The clutch piston mass has almost no influence on the dynamic characteristics of the hydraulic system. This is because the inertia force of the piston is very small compared to the preload force of the clutch return spring. Therefore, the influence of the clutch piston mass on the pressure response of the hydraulic system can be ignored.

[0023] (7) Considering that the operating temperature of the automatic transmission hydraulic system is 60-90°C, the hydraulic oil temperature in the range of 40-60°C has a significant impact on the response time. The higher the temperature, that is, the lower the viscosity, the faster the response time of the oil pressure step response, but the longer the step response time. Therefore, considering only the oil pressure response speed, the oil temperature should be controlled at a lower level as much as possible.

[0024] Furthermore, the sensitivity analysis method is used to explore the influence of internal and external parameters on the pressure and efficiency of the hydraulic system, and to determine the main optimization variables of the hydraulic system, including: based on the sensitivity analysis method, the selected characteristic vectors are normalized, and the influence of the standardized internal and external parameters on the efficiency of the automatic transmission hydraulic system is explored. The design parameters that have a significant impact on the efficiency of the hydraulic system are ranked in order of influence: clutch return spring stiffness, damping hole at the right end of the solenoid valve, and clutch effective area; and with the increase of the return spring and spring preload, that is, the increase of the spring stiffness and the initial compression, the smaller the clutch effective area, that is, the smaller the clutch outer diameter, the smaller the damping hole size, and the higher the efficiency of the hydraulic system.

[0025] Furthermore, the genetic algorithm is used to optimize the main optimization variables of the hydraulic system within the range allowed by the parameters, including: designing a PID controller to track the pressure of the hydraulic system, the reference oil pressure tracked is the change of oil pressure under the actual vehicle shifting condition, and the output oil pressure of the clutch pressure regulation system is basically fitted with the clutch oil chamber oil pressure collected under the actual shifting condition;

[0026] A vehicle dynamics model that reflects the shifting quality of the loader is established in AMEsim software, which mainly includes sub-models such as the engine power input module, the mechanical transmission system and shift clutch module, and the vehicle body and road surface module.

[0027] The smoothness and speed of the vehicle shifting process are a pair of contradictory attributes. In practical applications, it is necessary to combine the evaluation criteria of the shifting performance to balance the two attributes. The methods for evaluating the shifting quality mainly include the shifting impact J, the sliding friction work W of the friction pair, and the shifting time t;

[0028] The shift shock J is expressed as the derivative of the vehicle's driving acceleration a. It can show the smoothness of the vehicle during the shift process and is not affected by factors such as road surface differences, sudden changes in working conditions, and driver manipulation. It can better and quantitatively evaluate the vehicle's driving state and torque fluctuation during the shift process. Considering that the shift process is relatively short, it is approximately assumed that T d is a constant, the impact degree is simplified to:

[0029]

[0030] In the formula, w d represents the driving wheel speed, wt represents the transmission output shaft speed, i0 represents the transmission ratio of the drive axle, r is the radius of the drive wheel, J t represents the moment of inertia of the part connected to the transmission output shaft, and v represents the vehicle's speed;

[0031] The sliding friction work W of the friction pair is the work done by the friction torque of the master and driven plates during the clutch sliding stage. During the shifting process, the sliding friction work generated by the engagement and separation of the clutch will be converted into heat energy. The rapid temperature rise of the clutch friction plate and other components will lead to the deterioration of their operating environment and accelerated wear, which in turn affects the service life of the clutch, which is particularly obvious and critical in the field of engineering machinery. Therefore, the sliding friction work can be regarded as an evaluation indicator of the life of the friction components. The value of the sliding friction work should be as small as possible, and the longer the life of the shifting execution component. However, there is a certain degree of contradiction between the sliding friction work and the impact degree, so it is necessary to adjust through the control method to ensure that both are within a reasonable range.

[0032] The shift time t is the time from when the shift signal is sent to when the new gear is stable, which can indicate the rapidity of the shift. Its value has different degrees of influence on various vehicle performances (such as power, ride comfort, etc.) and component characteristics (such as clutch torque transmission characteristics and service life).

[0033] In order to unify the smoothness and rapidity of gear shifting, the sliding friction work W and impact degree J of the friction pair are set as optimization targets; the gear shift time t is set as a constraint condition; for the optimization of multi-objective functions, the linear weighted method can be used to construct the objective function. However, the sliding friction work and impact degree of the friction pair are two quantities of different properties and have different orders of magnitude. The objective function needs to be normalized. The normalized objective function is:

[0034]

[0035] Where W is the current slip work of the clutch, W0 is the final slip work of the clutch; J is the current impact degree, J0 is the maximum impact degree; ω is the weighting coefficient; considering that the research object is a loader and there is ablation of the clutch friction plate, ω is taken as 0.8.

[0036] The three parameters with significant influence on the dynamic response characteristics, namely the clutch return spring preload, the damping hole at the right end of the solenoid valve and the clutch effective area (outer diameter), are taken as optimization variables and the optimization range is set; the target parameter value changes with the increase of the evolutionary generation, until the parameter value basically tends to be stable after the evolutionary generation is greater than 500.

[0037] The beneficial effects of the present invention are:

[0038] (1) The present invention takes the automatic transmission actuator for a loader as the research object, and based on the dynamic model of the automatic transmission actuator considering the electromechanical and hydraulic characteristics, analyzes the dynamic response characteristics of the actuator pressure and efficiency under different design parameters and control parameters, and compares the influence of each parameter based on the sensitivity analysis method and determines the key optimization variables of the actuator.

[0039] (2) The present invention designs a PID controller to track the clutch oil chamber oil pressure acquisition value under actual shifting conditions, based on the vehicle dynamics model including engine input module, mechanical transmission and shifting clutch module, vehicle body and road surface module and other submodules. Taking into account the actual working characteristics of engineering machinery, the sliding friction work and impact degree of the friction pair are used as multi-objective optimization functions, the shifting time setting is used as a constraint condition, and the parameters with significant influence on the dynamic response characteristics are used as optimization variables. The genetic algorithm is used to search for the optimal parameters within a reasonable range to achieve the improvement of the shifting quality of the automatic transmission actuator and the forward optimization design.

[0040] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0042] Figure 1 A flow chart of the automatic transmission actuator parameter optimization method provided by the present invention;

[0043] Figure 2 A dynamic response characteristic of an automatic transmission actuator provided by an embodiment of the present invention;

[0044] Figure 3 The invention provides an embodiment of the present invention to provide an automatic transmission hydraulic system parameter based on a sensitivity analysis method to determine the degree of influence on its performance;

[0045] Figure 4 A vehicle dynamics model capable of reflecting the shifting quality of engineering machinery provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0046] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0047] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0048] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0049] See also Figure 1 to Figure 4 The present invention provides a method for optimizing the parameters of an automatic transmission actuator based on sensitivity analysis and genetic algorithm. Figure 1 As shown in the figure, the dynamic model of the automatic transmission actuator considering the electromechanical and hydraulic characteristics is established, which mainly includes the dynamic models of key components such as the gear pump, proportional solenoid valve and clutch. Among them, the hydraulic oil is taken out from the oil pool under the action of the mechanical gear pump and passes through the coarse filter and the fine filter. According to the required oil pressure of each clutch in the shift control strategy, it is distributed to the corresponding proportional solenoid valve. Considering that this hydraulic system is a full-flow direct-acting control, it directly flows into the clutch under each gear. According to the dynamic response characteristics of the hydraulic system pressure and efficiency of different design parameters and control parameters, the main optimization variables with significant influence are determined. Taking the shift quality as the optimization target and boundary condition, the shift quality of the automatic transmission actuator is improved through intelligent algorithms and the forward optimization design is completed.

[0050] 1. Construction of the dynamic model of the automatic transmission actuator considering the electromechanical and hydraulic characteristics and analysis of its dynamic response characteristics

[0051] (1) Based on the working principle and structure diagram of the main oil circuit regulation subsystem and the actuator, an automatic transmission actuator dynamic simulation model is established through AMEsim, which takes into account the electromechanical and hydraulic characteristics and includes key components such as gear pumps, proportional solenoid valves and clutches. Under the action of the mechanical gear pump, the hydraulic oil is taken out from the oil pool and passes through the coarse filter and fine filter, and is distributed to each proportional solenoid valve according to the required oil pressure of each clutch in the shift control strategy. According to the physical parameters of the key components in the main oil circuit regulation subsystem and the actuator, the dynamic simulation HCD model parameters are set.

[0052] The clutch engagement process can be divided into three stages, namely, the friction plate free clearance elimination stage, the sliding friction stage, and the pressing stage. Analysis shows that the piston assembly is affected by inertia force, fluid force, spring force, piston seal ring friction resistance, and piston viscous friction resistance. The dynamic equilibrium equation of the clutch piston assembly is:

[0053]

[0054] Where M L is the mass of the piston and one third of the spring, kg; x L is the piston displacement, m; P L is the internal pressure of the clutch cylinder, Pa; d1 is the outer diameter of the clutch, m; d2 is the inner diameter of the clutch, m; K LS is the return spring stiffness, N / m; x Lo is the initial compression of the spring, m; α is the damping coefficient of the sealing ring; b is the width of the sealing ring, m; B Lc is the viscous damping coefficient, N·s / m.

[0055] When the clutch is disengaged and engaged, the oil cylinder is in the oil discharge and oil filling stages respectively. Considering the compressibility of the oil, the oil volume changes differently during oil filling and oil discharge. Assuming there is no oil leakage, the flow rates during the oil filling and oil discharge stages are:

[0056]

[0057] In the formula, C = d 2 / (32μl), where d is the diameter of the throttle hole; μ is the viscosity of the oil; l is the length of the throttle hole; A is the area of ​​the flow cross section of the throttle hole, m 2 ; V L is the initial volume of the oil cylinder, m 3 ; S L is the piston action area, m 2 .

[0058] The torque transmitted by the clutch is different in the normal engagement state with the gear fixed and during the gear shifting process. The torque transmitted by the clutch under the two different working conditions is:

[0059]

[0060] Where, T c The clutch transmits torque, N·m; T load is the load torque, N·m, i.e. the required torque of the vehicle; the second formula is the torque transmitted by the clutch during the clutch shifting process, n is the number of friction pairs; r is the working radius of the friction plate, m; F LS is the spring force.

[0061] (2) The parameters that affect the dynamic response characteristics of the automatic transmission hydraulic system are mainly divided into two categories: one is the artificially designed internal parameters such as spring stiffness, initial spring compression, valve core mass and damping hole diameter; the other is the external factors that change with working conditions such as hydraulic oil temperature and viscosity. The dynamic response characteristics of the automatic transmission hydraulic system are studied by different design parameters and control parameters, such as Figure 2 As shown, it provides a reference for the optimal design of hydraulic system components and the control of pressure and flow. The analysis results of dynamic response characteristics are as follows:

[0062] ① The influence of the spring parameters of the proportional solenoid valve on the dynamic response characteristics of the hydraulic system pressure: The spring mainly plays the role of adjusting the valve core position, thereby changing the valve port size, and finally obtaining the target pressure or target flow. Considering the error in the actual measurement data, the spring stiffness k and the initial spring compression x of the proportional solenoid valve in the hydraulic system are analyzed in a suitable range. o Impact on the dynamic response characteristics of the hydraulic system. As the spring stiffness increases, the dynamic response and stable value of pressure remain almost unchanged, but the response time of the oil pressure is significantly delayed. The effect of the initial compression of the spring on the pressure response is similar to that of the spring stiffness. As the initial compression of the spring increases, the greater the spring force, the dynamic response and stable value of pressure remain almost unchanged, but the response time of the oil pressure is significantly delayed. It can be seen that the initial compression of the spring has a more obvious effect on the hysteresis of the oil pressure of the solenoid valve than the spring stiffness.

[0063] ② The influence of the valve core mass of the proportional solenoid valve on the dynamic response characteristics of the hydraulic system pressure: The inertia of an object is related to its mass and has an impact on the movement of the object. When the valve core mass increases from 0.015Kg to 0.035Kg, the dynamic response characteristics of the clutch control oil pressure change very little.

[0064] ③ The influence of damping hole size on the dynamic response characteristics of hydraulic system pressure: There are many damping holes in the actual object and schematic diagram of the automatic transmission hydraulic system, which can buffer and suppress the fluctuations of pressure and flow, and play a vital role in the stability and safety of the entire hydraulic system. In general, different damping hole sizes have a certain influence on the dynamic response characteristics of the shift oil pressure. With the increase of the damping hole diameter, the system output pressure response tends to become faster, and the larger the diameter, the weaker the trend of faster response, but the pressure fluctuation intensifies. The damping hole size at both ends of the solenoid valve mainly affects the response time of the friction plate free clearance stage, and the right end damping hole size has a greater impact, and it will also cause pressure fluctuations in the clutch clamping stage; the damping hole size of the clutch actuator mainly affects the time of the clutch clamping stage.

[0065] ④ The influence of piston outer diameter / piston action area on the dynamic response characteristics of hydraulic system pressure: Considering that the piston inner diameter is limited by the automatic transmission shaft, changing the piston action area can only be achieved by changing the clutch outer diameter. Analyze the clutch piston action area (piston outer diameter d p ) on the dynamic response characteristics of the hydraulic system. As the outer diameter of the clutch increases, the oil pressure in the oil chamber decreases, and the pressure response speed slows down. This is mainly because as the outer diameter of the clutch increases, the volume of the oil cylinder chamber increases, the time required to fill the oil chamber becomes longer, and the pressure response slows down accordingly.

[0066] ⑤ The influence of clutch return spring on the dynamic response characteristics of hydraulic system pressure: return spring preload (return spring stiffness k c and initial compression x c ) has a certain influence on the clutch idle stroke and sliding friction stage, and analyzes the influence of the return spring preload on the dynamic response characteristics of the hydraulic system within a reasonable range. The greater the clutch return spring stiffness and initial compression, the greater the corresponding return spring preload, the more delayed the piston movement, and the slower the increase in the cylinder volume, so the pressure value of the hydraulic oil in the oil chamber is larger. It can be seen that the return spring stiffness has a more significant effect on the piston hydraulic oil pressure boost stage relative to the initial compression.

[0067] ⑥ The influence of clutch piston mass on the dynamic response characteristics of hydraulic system pressure: The influence of clutch piston mass m on the dynamic response characteristics of hydraulic system is analyzed within a reasonable range. The clutch piston mass has almost no effect on the dynamic characteristics of the hydraulic system. This is because the inertia force of the piston is very small compared to the preload force of the clutch return spring. Therefore, the influence of the clutch piston mass on the pressure response of the hydraulic system can be ignored.

[0068] ⑦ Considering that the working temperature of the automatic transmission hydraulic system is 60-90℃, the hydraulic oil temperature in the range of 40-60℃ has a significant impact on the response time. The higher the temperature, the lower the viscosity, the faster the response time of the oil pressure step response, but the longer the step response time. Therefore, considering only the oil pressure response speed, the oil temperature should be controlled at a lower level as much as possible.

[0069] (3) Considering the differences in the selection of parameter feature ranges, the selected feature vectors are normalized based on the sensitivity analysis method, and the influence of the standardized internal and external parameters on the efficiency of the automatic transmission hydraulic system is explored. Figure 3 As shown in the figure, the design parameters that have a significant impact on the efficiency of the hydraulic system are ranked in order of influence: clutch return spring stiffness, damping hole at the right end of the solenoid valve, and clutch action area. And as the return spring and spring preload increase (increase in spring stiffness and initial compression), the clutch action area becomes smaller (the clutch outer diameter becomes smaller), and the damping hole size becomes smaller, the hydraulic system efficiency becomes higher.

[0070] Normalization formula:

[0071]

[0072] 2. Parameter optimization design of automatic transmission actuator based on genetic algorithm

[0073] A PID controller is designed to track the pressure of the hydraulic system. The tracked reference oil pressure is the change of oil pressure under the actual vehicle shifting condition. The output oil pressure of the clutch pressure regulation system is basically consistent with the clutch oil chamber oil pressure collected under the actual shifting condition.

[0074] In AMEsim software, Figure 4 The vehicle dynamics model reflecting the shifting quality of the loader shown is mainly composed of sub-models such as the engine power input module 1, the mechanical transmission system 3 and the shift clutch module 2, and the vehicle body and road surface module 4.

[0075] The smoothness and speed of the vehicle shifting process are a pair of contradictory attributes. In practical applications, the two attributes need to be balanced by combining the evaluation criteria of the shifting performance. The methods for evaluating the shifting quality mainly include the shifting shock J, the sliding friction work W of the friction pair, and the shifting time t.

[0076] The shift shock J is expressed as the derivative of the vehicle's driving acceleration a. It can show the smoothness of the vehicle during the shift process and is not affected by factors such as road surface differences, sudden changes in working conditions, and driver manipulation. It can better and quantitatively evaluate the vehicle's driving state and torque fluctuation during the shift process. Considering that the shift process is relatively short, it is approximately assumed that T d is a constant, the impact degree is simplified to:

[0077]

[0078] In the formula, w d represents the driving wheel speed, w t represents the transmission output shaft speed, i0 represents the transmission ratio of the drive axle, r is the radius of the drive wheel, J t It represents the moment of inertia of the part connected to the transmission output shaft, and v represents the vehicle's speed.

[0079] The sliding friction work W of the friction pair is the work done by the friction torque of the master and driven plates during the clutch sliding stage. During the shifting process, the sliding friction work generated by the engagement and separation of the clutch will be converted into heat energy. The rapid temperature rise of the clutch friction plate and other components will lead to the deterioration of their operating environment and accelerated wear, which in turn affects the service life of the clutch, which is particularly obvious and critical in the field of engineering machinery. Therefore, the sliding friction work can be regarded as an evaluation indicator of the life of the friction components. The value of the sliding friction work should be as small as possible, and the longer the life of the shifting execution component. However, there is a certain degree of contradiction between the sliding friction work and the impact degree, so it is necessary to adjust through the control method to ensure that both are within a reasonable range.

[0080] The shift time t is the time from when the shift signal is sent to when the new gear is stable, which can indicate the rapidity of the shift. Its value has different degrees of influence on various vehicle performances (such as power, ride comfort, etc.) and component characteristics (such as clutch torque transmission characteristics and service life).

[0081] In order to unify the smoothness and rapidity of gear shifting, the friction work W and impact J of the friction pair are set as optimization targets; the gear shift time t is set as a constraint. For the optimization of multi-objective functions, the linear weighted method can be used to construct the objective function. However, the friction work and impact of the friction pair are two quantities of different nature and have different orders of magnitude. The objective function needs to be normalized. The normalized objective function is:

[0082]

[0083] Where W is the current friction work of the clutch, W0 is the final friction work of the clutch, J is the current impact degree, J0 is the maximum impact degree, and ω is the weighting coefficient. Considering that the research object is a loader and there is ablation of the clutch friction plate, ω is taken as 0.8.

[0084] The three parameters with significant influence on the dynamic response characteristics, namely the clutch return spring preload, the damping hole at the right end of the solenoid valve, and the clutch action area (outer diameter), are used as optimization variables and the optimization range is set. The target parameter value changes with the increase of the evolutionary generation, until the parameter value basically stabilizes after the evolutionary generation is greater than 500.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A method for optimizing the parameters of an automatic transmission actuator based on sensitivity analysis and genetic algorithm, characterized in that: A dynamic model of the automatic transmission actuator considering the electromechanical and hydraulic characteristics is established, including the dynamic models of the gear pump, proportional solenoid valve and clutch; the dynamic response characteristics of the automatic transmission hydraulic system and actuator under different design parameters and control parameters are analyzed, and the sensitivity analysis method is used to explore the influence of internal and external parameters on the pressure and efficiency of the hydraulic system, and the main optimization variables of the hydraulic system are determined; according to the required oil pressure of each solenoid valve and clutch in the shift control strategy, a controller is designed to track the pressure of the hydraulic system; with the shift shock degree and the sliding friction work of the friction pair as the optimization goals, and the shift time as the constraint condition, the genetic algorithm is used to optimize the main optimization variables of the hydraulic system within the range allowed by the parameters, and the shift quality improvement and forward optimization design of the automatic transmission actuator are completed.

2. The automatic transmission actuator parameter optimization design method according to claim 1, characterized in that: The dynamic model of the automatic transmission actuator considering the electromechanical and hydraulic characteristics is established, including: the hydraulic oil is taken out from the oil pool under the action of the mechanical gear pump and passes through the coarse filter and the fine filter, and is distributed to each proportional solenoid valve according to the required oil pressure of each clutch in the shift control strategy; according to the physical parameters of the main oil circuit regulation subsystem and the key components in the actuator, the dynamic simulation HCD model parameters are set; The clutch engagement process is divided into three stages, namely, the friction plate free clearance elimination stage, the sliding friction stage and the pressing stage. It is known from the analysis that the piston assembly is affected by inertia force, fluid force, spring force, piston sealing ring friction resistance and piston viscous friction resistance, and the dynamic equilibrium equation of the clutch piston assembly is: Where M L is the mass of the piston and one third of the spring; P L is the internal pressure of the clutch cylinder; d1 is the outer diameter of the clutch; d2 is the inner diameter of the clutch; K LS is the return spring stiffness; x L is the piston displacement; x Lo is the initial compression of the spring; α is the damping coefficient of the sealing ring; b is the width of the sealing ring; B Lc is the viscous damping coefficient; When the clutch is disengaged and engaged, the oil cylinder is in the oil discharge and oil filling stages respectively. Considering the compressibility of the oil, the oil volume changes differently during oil filling and oil discharge. Assuming there is no oil leakage, the flow rate Q in the oil filling and oil discharge stages is L They are: In the formula, C = d 2 / (32μl), where d is the diameter of the throttle hole; μ is the viscosity of the oil; l is the length of the throttle hole; A is the area of ​​the flow cross section of the throttle hole; V L is the initial volume of the oil cylinder; S L is the piston action area; The torque transmitted by the clutch is different in the normal engagement state with the gear fixed and during the gear shifting process. The torque transmitted by the clutch under the two different working conditions is: Where, T c Transmits torque to the clutch; T load is the load torque, i.e. the required torque of the vehicle; the second formula is the torque transmitted by the clutch during the clutch shifting process, n is the number of friction pairs; r is the working radius of the friction plate; F LS is the spring force.

3. The automatic transmission actuator parameter optimization design method according to claim 2, characterized in that: Analyze the dynamic response characteristics of the automatic transmission hydraulic system and actuator under different design parameters and control parameters, including: (1) The influence of the spring parameters of the proportional solenoid valve on the dynamic response characteristics of the hydraulic system pressure: The spring plays a role in adjusting the valve core position, thereby changing the valve port size and finally obtaining the target pressure or target flow. Considering the error in the actual measurement data, the spring stiffness k and the initial spring compression x of the proportional solenoid valve in the hydraulic system are analyzed within a suitable range. o Impact on the dynamic response characteristics of the hydraulic system; the initial compression of the spring has a more obvious effect on the oil pressure hysteresis of the solenoid valve than the spring stiffness; (2) The influence of the valve core mass of the proportional solenoid valve on the dynamic response characteristics of the hydraulic system pressure: The inertia of an object is related to its mass and has an impact on the movement of the object; when the valve core mass increases from 0.015Kg to 0.035Kg, the dynamic response characteristics of the clutch control oil pressure change very little; (3) The influence of damping hole size on the dynamic response characteristics of hydraulic system pressure: The damping hole size at both ends of the solenoid valve affects the response time of the friction plate free gap elimination stage, and the damping hole size at the right end has a greater impact, and it will also cause pressure fluctuations in the clutch clamping stage; the damping hole size of the clutch actuator affects the time of the clutch clamping stage; (4) The influence of piston outer diameter or piston action area on the dynamic response characteristics of hydraulic system pressure: As the outer diameter of the clutch increases, the oil pressure in the oil chamber decreases, and the pressure response speed slows down; (5) The influence of clutch return spring on the dynamic response characteristics of hydraulic system pressure: The return spring preload includes the return spring stiffness k c and initial compression x c It has an impact on the clutch idle stroke and slipping stage. The impact of the return spring preload on the dynamic response characteristics of the hydraulic system is analyzed within a reasonable range. The return spring stiffness has a more significant impact on the piston hydraulic oil pressure increase stage relative to the initial compression. (6) The influence of clutch piston mass on the dynamic response characteristics of hydraulic system pressure: The influence of clutch piston mass on the pressure response of hydraulic system can be ignored; (7) Considering that the operating temperature of the automatic transmission hydraulic system is 60-90°C, the hydraulic oil temperature in the range of 40-60°C has a significant impact on the response time. The higher the temperature, that is, the lower the viscosity, the faster the response time of the oil pressure step response, but the longer the step response time. Therefore, considering only the oil pressure response speed, the oil temperature should be controlled at a low level as much as possible.

4. The automatic transmission actuator parameter optimization design method according to claim 3, characterized in that: The sensitivity analysis method is used to explore the influence of internal and external parameters on the pressure and efficiency of the hydraulic system, and to determine the main optimization variables of the hydraulic system, including: based on the sensitivity analysis method, the selected characteristic vectors are normalized, and the influence of the standardized internal and external parameters on the efficiency of the automatic transmission hydraulic system is explored. The design parameters that have a significant impact on the efficiency of the hydraulic system are ranked in order of influence: clutch return spring stiffness, damping hole at the right end of the solenoid valve and clutch effective area; and with the increase of the return spring and spring preload, that is, the increase of the spring stiffness and the initial compression, the smaller the clutch effective area, that is, the smaller the clutch outer diameter, the smaller the damping hole size, and the higher the efficiency of the hydraulic system.

5. The automatic transmission actuator parameter optimization design method according to claim 1, characterized in that: Genetic algorithms are used to optimize the main optimization variables of the hydraulic system within the range allowed by parameters, including: designing a PID controller to track the pressure of the hydraulic system. The reference oil pressure tracked is the change of oil pressure under the actual vehicle shifting condition. The output oil pressure of the clutch pressure regulation system is basically fitted with the clutch oil chamber oil pressure collected under the actual shifting condition. A vehicle dynamics model that reflects the shifting quality of the loader is established in AMEsim software, including the engine power input module, the mechanical transmission system and shift clutch module, and the vehicle body and road surface module; Methods for evaluating shift quality include shift shock J, sliding friction work W of the friction pair, and shift time t; The shift shock J is expressed as the derivative of the vehicle's driving acceleration a. It can show the smoothness of the vehicle during the shift process and is not affected by road surface differences, sudden changes in working conditions, and driver manipulation. It can quantitatively evaluate the vehicle's driving state and torque fluctuation during the shift process. Considering the short shift process, it is approximately assumed that T d is a constant, the impact degree is simplified to: In the formula, w d represents the driving wheel speed, w t represents the transmission output shaft speed, i0 represents the transmission ratio of the drive axle, r is the radius of the drive wheel, J t represents the moment of inertia of the part connected to the transmission output shaft, and v represents the vehicle's speed; In order to unify the smoothness and rapidity of gear shifting, the friction work W and impact J of the friction pair are set as optimization targets; the shift time t is set as a constraint condition; for the optimization of multi-objective functions, the linear weighted method is used to construct the objective function. However, the friction work and impact of the friction pair are two quantities of different nature and have different orders of magnitude, so the objective function needs to be normalized. The normalized objective function is: Where, W is the current friction work of the clutch, W0 is the final friction work of the clutch; J is the current impact degree, J0 is the maximum impact degree; ω is the weighting coefficient; The three parameters with significant influence on the dynamic response characteristics, namely the clutch return spring preload, the damping hole at the right end of the solenoid valve and the clutch action area, are taken as optimization variables and the optimization range is set; the target parameter value changes with the increase of the evolutionary generation, and the parameter value basically tends to be stable after the evolutionary generation is greater than 500.

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