Central differential dynamic adjustment method based on torque distribution optimization

Abstract

The invention relates to the technical field of central differential adjustment, in particular to a torque distribution optimization-based central differential dynamic adjustment method, which comprises the following steps of: predicting a driving state based on a vehicle dynamics model and generating a feedforward torque distribution reference instruction; monitoring the rotating speed difference of front and rear drive axles in real time and generating a feedback torque correction instruction; the feedforward instruction and the feedback instruction are superposed to generate a total torque distribution instruction, and a central differential mechanism is controlled to execute inter-axle torque distribution; when it is detected that an individual wheel slips, the control system cooperates with an electronic stability program controller to work, and a total torque distribution instruction is dynamically adjusted by interacting a cooperation request and braking state information so as to achieve accurate distribution of driving torque to the best attached wheel; and meanwhile, the temperature of the multiple clutches is monitored in real time, predictive thermal management control or system protection strategies are executed in a graded mode according to temperature threshold values, and the reliability and durability of system work are ensured.

Description

Technical Field

[0001] This invention relates to the field of central differential adjustment technology, and in particular to a dynamic adjustment method for a central differential based on torque distribution optimization. Background Technology

[0002] Four-wheel drive technology aims to improve a vehicle's traction, off-road capability, and driving stability. The center differential, as the core component of the four-wheel drive system, functions to distribute power appropriately between the front and rear drive axles. Currently, most mainstream active center differential systems based on multi-plate clutches employ a feedback control strategy. This involves real-time monitoring of the speed difference between the front and rear axles; only when slippage is detected in one axle will the multi-plate clutch be engaged to redistribute torque. This sense-response control mode provides an effective solution to fundamental problems related to wheel slippage and power transmission.

[0003] However, this feedback control mechanism, which relies on post-event remediation, has inherent flaws. The most prominent problem is the delay in system response, which makes the traction and stability control of the vehicle in complex conditions not timely and smooth enough. Specifically, there is a significant time lag from the occurrence of slippage to its detection and the completion of torque redistribution. When accelerating rapidly on low-traction surfaces or cornering at high speeds, this delay may lead to instantaneous power interruption, continuous wheel spinning, and even affect the dynamic stability of the vehicle body. In addition, the system usually operates independently and does not coordinate well with other electronic control systems of the vehicle (such as electronic stability program), making it difficult to achieve optimal utilization of adhesion at the vehicle level. Summary of the Invention

[0004] To overcome the above shortcomings, the present invention provides an image recognition method, which aims to improve the problem that the system response delay in the prior art leads to insufficient and untimely control of traction and stability of vehicles under complex working conditions.

[0005] In a first aspect, the present invention provides the following technical solution: a dynamic adjustment method for a central differential based on torque distribution optimization, comprising the following steps:

[0006] The system collects the vehicle's drive demand signal, vehicle dynamic signal, and wheel dynamic signal. Based on the drive demand signal, vehicle dynamic signal, and wheel dynamic signal, it uses a preset vehicle dynamics model to predict the vehicle's driving state trend and the load change trend of the front and rear drive axles at the next moment, and obtains and outputs the feedforward torque distribution reference command.

[0007] Based on wheel dynamic signals, the actual speed difference between the front and rear drive axles is calculated in real time, and the actual speed difference is compared with a preset speed difference threshold to generate a feedback torque correction command.

[0008] The feedforward torque distribution reference command and the feedback torque correction command are superimposed to generate the final total torque distribution command, and the total torque distribution command is sent to the actuator of the central differential to control the clamping force of the multi-plate clutch of the central differential and perform inter-shaft torque distribution.

[0009] It can detect in real time whether individual wheels are slipping. If it does, it sends a wheel-to-wheel slip limiting coordination request to the electronic stability program controller.

[0010] The system receives wheel braking status information from the electronic stability program controller in response to the wheel-to-wheel limited-slip coordination request, and maintains or adjusts the total torque distribution command based on this information to coordinate the direction of drive torque to the wheel with the best traction conditions.

[0011] The system monitors and estimates the real-time temperature of the multi-plate clutch in the central differential under slipping conditions. The real-time temperature is compared with a preset first temperature threshold and a higher second temperature threshold. If the real-time temperature is higher than the first temperature threshold but lower than the second temperature threshold, predictive thermal management control is executed. If the real-time temperature reaches or exceeds the second temperature threshold, a system protection strategy is executed.

[0012] Preferably, the process for obtaining the feedforward torque distribution reference command includes:

[0013] The driving demand signal, vehicle dynamic signal and wheel dynamic signal are acquired in real time, and the signals are filtered and validated to obtain the vehicle state parameter set at the current moment.

[0014] The current vehicle state parameter set is input into the preset vehicle dynamics model. By calculating the vehicle's longitudinal and lateral dynamic equations, the longitudinal acceleration, lateral acceleration, and yaw rate trends of the vehicle in the next sampling period are predicted.

[0015] Based on the predicted longitudinal acceleration and lateral acceleration trends, and combined with preset vehicle mass parameters and wheelbase and track parameters, the dynamic load transfer of the front and rear drive axles caused by the inertial force generated by vehicle acceleration and deceleration and the centrifugal force generated by vehicle steering is calculated.

[0016] Based on the dynamic load transfer amount and according to the principle that the drive axle with increased load can obtain greater drive torque, a feedforward torque distribution reference command for optimizing vehicle traction and stability at the next moment is calculated.

[0017] Preferably, the prediction process for the longitudinal acceleration change trend, the lateral acceleration change trend, and the yaw rate change trend includes:

[0018] Based on the throttle opening and current vehicle speed in the drive demand signal, the expected driving force of the vehicle is calculated using a preset engine torque MAP and transmission system model.

[0019] Based on the current vehicle speed and the preset vehicle driving resistance model, the driving resistance experienced by the vehicle is calculated.

[0020] Based on the difference between the expected driving force and the driving resistance, combined with the preset vehicle mass, the longitudinal acceleration change trend in the next sampling period is estimated by calculating using Newton's second law.

[0021] Based on the steering wheel angle in the vehicle dynamic signal, the lateral force acting on the front wheels of the vehicle is calculated using a preset steering system transmission ratio and a vehicle tire lateral slip characteristic model.

[0022] Based on the lateral force of the front wheel, the current vehicle speed, and the preset vehicle center of gravity position and moment of inertia parameters, the lateral acceleration and yaw rate trends in the next sampling period are simultaneously estimated using a two-degree-of-freedom bicycle model.

[0023] Preferably, the process for generating the feedback torque correction command includes:

[0024] Based on the collected wheel dynamic signals, the average speed of the front drive axle and the average speed of the rear drive axle are calculated respectively.

[0025] The actual speed difference between the front and rear drive axles is calculated based on the average speed of the front drive axle and the average speed of the rear drive axle.

[0026] The calculated actual speed difference is compared with a preset speed difference threshold. If the actual speed difference is less than or equal to the speed difference threshold, the vehicle is determined to be in a stable driving state, and a feedback torque correction command with a value of zero is generated. If the actual speed difference is greater than the speed difference threshold, it is determined that the drive axle is slipping, and the feedback correction amount calculation process is entered.

[0027] Based on the amount by which the actual speed difference exceeds the speed difference threshold, a feedback torque correction amount for eliminating the speed difference is calculated using a preset proportional-integral control algorithm, and the feedback torque correction amount is assigned to the feedback torque correction command.

[0028] Preferably, the process for generating the final total torque distribution command includes:

[0029] The signal validity of the feedforward torque distribution reference command and the feedback torque correction command is verified.

[0030] The effective feedforward torque distribution reference command and the feedback torque correction command are respectively subjected to amplitude limiting processing based on a preset output range;

[0031] The feedforward torque distribution reference command after amplitude limiting is algebraically added to the feedback torque correction command to obtain an initial total torque distribution command.

[0032] The initial total torque distribution command is input to a first-order low-pass filter for smoothing to suppress high-frequency jitter in the command.

[0033] The smoothed command is used as the final total torque distribution command and sent to the actuator of the center differential.

[0034] Preferably, the process for sending the inter-wheel limited-slip coordination request includes:

[0035] Based on the collected wheel dynamic signals, the wheel speed difference between two wheels on the same drive axle is calculated in real time and compared with a first preset threshold. At the same time, the slip ratio of a single wheel is calculated and compared with a second preset threshold.

[0036] If the wheel speed difference continues to exceed the first preset threshold, and / or the slip ratio continues to exceed the second preset threshold and reaches a preset duration, then it is determined that individual wheels on the drive axle are slipping.

[0037] When a slippage is detected by comprehensive assessment, the identification of the slipping wheel is determined as the target slipping wheel identification, and the intervention request level is determined based on the magnitude of the slippage rate.

[0038] Based on the target slipping wheel identifier and the requested intervention level obtained from the slipping state parameterization, an inter-wheel slip limiting coordination request is generated.

[0039] The generated inter-wheel limited-slip coordination request is sent to the electronic stability program controller via the controller area network bus.

[0040] Preferably, the process for maintaining or adjusting the total torque distribution command includes:

[0041] Analyze the wheel braking status information to obtain the actual braking pressure of the braked wheel;

[0042] The actual braking pressure is compared with the requested intervention level in the wheel-to-wheel limited-slip coordination request to evaluate the actual braking intervention effect of the electronic stability program controller.

[0043] If the evaluation results indicate that the actual braking intervention effect has met expectations, the current total torque distribution command is maintained. If the evaluation results indicate that the actual braking intervention effect has not met expectations, the total torque distribution command is modified based on the difference between the actual braking pressure and the expected braking pressure.

[0044] The maintained or modified total torque distribution command is used as the new control reference and output to the actuator of the center differential.

[0045] Preferably, the execution flow of the predictive thermal management control includes:

[0046] Based on the total torque distribution command, the clamping force of the multi-plate clutch, and the actual speed difference between the front and rear drive axles, calculate the slipping power consumed by the multi-plate clutch in the slipping state;

[0047] Based on the real-time temperature and the slippage power of the multi-plate clutch, the temperature rise trend is predicted.

[0048] Based on how close the temperature rise trend is to the first temperature threshold, an engine torque limit is calculated.

[0049] Send a torque limit request containing the engine torque limit amount to the engine controller to reduce the input torque transmitted to the center differential from the source;

[0050] With engine torque limited, the total torque distribution command is simultaneously optimized to reduce the torque distribution ratio to the drive axle that is currently slipping, thereby further reducing the slippage work of the multi-plate clutch.

[0051] The real-time temperature is continuously monitored. If the real-time temperature drops below the first temperature threshold and stabilizes, the torque limiting request is released and the normal torque distribution logic is restored.

[0052] Preferably, the execution process of the system protection strategy includes:

[0053] A forced command is generated and sent to the actuator of the central differential to reduce the clamping force of the multi-plate clutch to a preset minimum safety value, so as to cut off or significantly reduce the power transmission to the rear drive axle and put the vehicle into front-wheel drive mode.

[0054] A high temperature fault alarm signal is generated, and visual and / or auditory warning information is output to the driver through the instrument cluster, indicating that the four-wheel drive system is temporarily limited in function due to overheating.

[0055] The control state of the central differential is locked in the front-wheel drive mode, and the real-time temperature is continuously monitored until the real-time temperature drops below a preset third temperature recovery threshold.

[0056] When the real-time temperature drops below the third temperature recovery threshold, the system state lock is released, and the clamping force of the multi-plate clutch and the normal torque distribution control logic are gradually restored according to the preset recovery rate.

[0057] Secondly, the present invention provides the following technical solution: a dynamic adjustment system for a central differential based on torque distribution optimization, comprising the following modules:

[0058] The state perception and prediction module is used to collect the vehicle's driving demand signal, vehicle dynamic signal and wheel dynamic signal. Based on the driving demand signal, vehicle dynamic signal and wheel dynamic signal, the module predicts the driving state trend of the vehicle and the load change trend of the front and rear drive axles at the next moment through a preset vehicle dynamics model, and obtains and outputs the feedforward torque distribution reference command.

[0059] The feedback correction module is used to calculate the actual speed difference between the front and rear drive axles in real time based on the wheel dynamic signal, compare the actual speed difference with a preset speed difference threshold, and generate a feedback torque correction command.

[0060] The torque distribution synthesis module is used to superimpose the feedforward torque distribution reference command and the feedback torque correction command to generate the final total torque distribution command, and send the total torque distribution command to the actuator of the central differential to control the clamping force of the multi-plate clutch of the central differential and perform inter-shaft torque distribution.

[0061] The wheel-to-wheel coordination decision module is used to determine in real time whether individual wheels are slipping. If the determination is yes, it sends a wheel-to-wheel limited-slip coordination request to the electronic stability program controller.

[0062] The inter-wheel coordination execution module is used to receive wheel braking status information from the electronic stability program controller in response to the inter-wheel limited slip coordination request, and maintain or adjust the total torque distribution command based on the information to coordinate the drive torque to the wheel with the best adhesion conditions.

[0063] The thermal management protection module is used to monitor and estimate the real-time temperature of the multi-plate clutch in the central differential under slipping conditions. The real-time temperature is compared with a preset first temperature threshold and a higher second temperature threshold. If the real-time temperature is higher than the first temperature threshold but lower than the second temperature threshold, predictive thermal management control is executed. If the real-time temperature reaches or exceeds the second temperature threshold, a system protection strategy is executed.

[0064] The present invention has the following beneficial effects:

[0065] 1. In this invention, by introducing a pre-set vehicle dynamics model, based on the driving demand signal and vehicle dynamic signal, it can proactively predict the vehicle's driving state and front and rear axle load changes at the next moment. Based on this, the generated feedforward torque distribution reference command can pre-adjust the torque distribution of the central differential before the wheel slippage trend occurs, thereby reducing the sense of power interruption caused by the detection and execution delay of traditional feedback control. This makes the power output and vehicle attitude change seamlessly connected. Especially in dynamic conditions such as rapid acceleration and cornering acceleration, the system response is more rapid, which not only improves traction efficiency, but also greatly enhances driving smoothness and driver confidence.

[0066] 2. In this invention, a closed-loop coordination mechanism is established between the central differential and the electronic stability program. When the system determines that individual wheels are slipping, it not only sends a coordination request, but also dynamically maintains or adjusts the inter-axle torque distribution based on the braking status information fed back by ESC. This linkage between inter-axle distribution and inter-wheel braking constitutes global torque optimization, which can accurately guide the driving torque to the only wheel with traction. This effectively solves the problem of power being wasted by the spinning wheel in harsh road conditions such as cross-axle situations in traditional systems. At the same time, this coordination mechanism can actively correct understeer or oversteer tendencies during aggressive driving, thereby improving the handling limits.

[0067] 3. In this invention, not only is the temperature monitored in real time, but the temperature rise trend is also predicted by calculating the sliding power. When the temperature reaches the first threshold, it actively coordinates with the engine management system to limit the input torque from the source and simultaneously optimize the torque distribution to reduce the heat source, thus realizing predictive thermal management control. This active cooling intervention, compared with the traditional passive protection of cutting off after overheating, can effectively avoid the sudden decline of system performance, ensure the continuity and reliability of the four-wheel drive system under long-term high-load conditions, and improve the robustness of the system and user experience. Attached Figure Description

[0068] Figure 1 This is a flowchart illustrating a dynamic adjustment method for a central differential based on torque distribution optimization proposed in this invention.

[0069] Figure 2 This is a schematic diagram of the architecture of a dynamic adjustment system for a central differential based on torque distribution optimization proposed in this invention. Detailed Implementation

[0070] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0071] Example 1:

[0072] In a first embodiment of the present invention, the present invention provides a method for dynamic adjustment of a central differential based on torque distribution optimization, such as... Figure 1 As shown, it includes the following steps:

[0073] The system collects the vehicle's drive demand signal, vehicle dynamic signal, and wheel dynamic signal. Based on these signals, and using a pre-set vehicle dynamics model, it predicts the vehicle's driving state trend and the load change trend of the front and rear drive axles at the next moment, and obtains and outputs the feedforward torque distribution reference command.

[0074] Furthermore, the process for obtaining the feedforward torque distribution reference command includes:

[0075] The system acquires driving demand signals, vehicle dynamic signals, and wheel dynamic signals in real time, and filters and verifies the rationality of the signals to obtain the vehicle state parameter set at the current moment.

[0076] The current vehicle state parameter set is input into the preset vehicle dynamics model. By calculating the vehicle's longitudinal and lateral dynamic equations, the longitudinal acceleration, lateral acceleration, and yaw rate trends of the vehicle in the next sampling period are predicted.

[0077] Based on the predicted longitudinal and lateral acceleration trends, and combined with preset vehicle mass parameters and wheelbase and track parameters, the dynamic load transfer of the front and rear drive axles caused by the inertial force generated by vehicle acceleration and deceleration and the centrifugal force generated by vehicle steering is calculated.

[0078] Based on the dynamic load transfer amount and the principle that the drive axle with increased load can obtain greater drive torque, a feedforward torque distribution reference command for optimizing vehicle traction and stability in the next moment is calculated.

[0079] Furthermore, the prediction process for the trends of longitudinal acceleration, lateral acceleration, and yaw rate includes:

[0080] Based on the throttle opening and current vehicle speed in the drive demand signal, the expected driving force of the vehicle is calculated through a preset engine torque MAP and transmission system model.

[0081] Based on the current vehicle speed and the preset vehicle driving resistance model, the driving resistance experienced by the vehicle is calculated.

[0082] Based on the difference between the expected driving force and the driving resistance, combined with the preset vehicle mass, the longitudinal acceleration change trend in the next sampling period is estimated by calculating using Newton's second law.

[0083] Based on the steering wheel angle in the vehicle dynamic signal, the lateral force acting on the front wheels of the vehicle is calculated by using a preset steering system transmission ratio and a vehicle tire side slip characteristic model.

[0084] Based on the lateral force of the front wheel, the current vehicle speed, and the preset parameters of the vehicle's center of gravity and moment of inertia, the lateral acceleration and yaw rate trends in the next sampling period are simultaneously predicted using a two-degree-of-freedom bicycle model.

[0085] Specifically, the driving demand signals include, but are not limited to, throttle opening and its rate of change; vehicle dynamic signals include, but are not limited to, steering wheel angle, yaw rate, lateral acceleration and longitudinal acceleration; and wheel dynamic signals include the real-time rotational speed of the four wheels. These signals are provided by existing sensors on the vehicle (such as throttle position sensor, steering angle sensor, inertial measurement unit IMU, wheel speed sensor). The system first filters (e.g., uses a low-pass filter to remove high-frequency noise) and performs rationality checks (e.g., determines whether the signal value is within the physically possible range) on the above raw signals to obtain a reliable set of vehicle state parameters at the current moment.

[0086] The processed vehicle state parameter set is input into a pre-set vehicle dynamics model. This model calculates longitudinal and lateral dynamics in parallel, predicts the motion trend of the next sampling period, queries a pre-calibrated engine torque MAP based on throttle opening and current vehicle speed, and calculates the expected driving force F transmitted to the drive wheels by combining the transmission ratio and mechanical efficiency of the transmission system. drive Based on the current vehicle speed, the total driving resistance F experienced by the vehicle is calculated using a pre-set driving resistance model. resist This resistance typically includes air resistance, rolling resistance, and slope resistance. According to Newton's second law, the predicted longitudinal acceleration a... x-pred It can be calculated using the following formula:

[0087]

[0088] Where m is the preset vehicle mass;

[0089] Based on steering wheel angle δ sw and the preset steering system gear ratio i s Calculate the average front wheel steering angle δ = δ sw / i s Based on vehicle speed v and a preset tire lateral characteristic model (which can usually be simplified to a linear model, i.e., lateral stiffness C), f The lateral force F of the front wheel was calculated. yf =C f • δ (under the assumption of small turning angle);

[0090] The lateral force F on the front wheel yf Current vehicle speed v and preset vehicle center of gravity position (wheelbase L, distance from center of gravity to front axle a), and vehicle moment of inertia I about the Z-axis. z As input, a simplified version of a classic four-wheeled vehicle model, such as a linear two-degree-of-freedom bicycle model, can be used. By solving the following set of dynamic equations, the lateral acceleration *a* can be simultaneously predicted. y-pred With yaw rate

[0091]

[0092] Among them, F yf This is the lateral force on the rear axle, a function of vehicle state parameters. Let γ be the yaw acceleration. γ can be obtained through numerical integration and other methods. pred ;

[0093] Based on the estimated longitudinal acceleration a x-pred With lateral acceleration a y-pred Based on the vehicle mass m, wheelbase L, track width T, and center of gravity height h, the dynamic load transfer and the increase in dynamic load ΔF of the rear axle caused by longitudinal acceleration are calculated. z_long It can be estimated as follows:

[0094]

[0095] The calculation of load transfer on the left and right wheels caused by lateral acceleration follows a similar principle. The calculation is a well-known technique in the field, and the formula will not be repeated here. By combining longitudinal and lateral load transfer, the dynamic load transfer amount of the front and rear drive axles can be obtained.

[0096] Based on the principle that a drive axle with increased load can obtain greater drive torque to optimize traction, the calculated dynamic load transfer amount is used as the basis for feedforward control. For example, if the calculation shows that the increase in rear axle load is ΔF... z-rear The system then calculates the corresponding feedforward torque distribution reference command T according to the preset mapping relationship. bias-ff The command can be a proportional value (such as the rear axle torque percentage) or a target clamping force command. Its core is to match the torque distribution with the predicted load distribution, so as to make better use of the ground adhesion in the next moment.

[0097] Based on wheel dynamic signals, the actual speed difference between the front and rear drive axles is calculated in real time, and the actual speed difference is compared with a preset speed difference threshold to generate a feedback torque correction command.

[0098] Furthermore, the process for generating feedback torque correction commands includes:

[0099] Based on the collected wheel dynamic signals, the average speed of the front drive axle and the average speed of the rear drive axle are calculated respectively.

[0100] The actual speed difference between the front and rear drive axles is calculated based on the average speed of the front drive axle and the average speed of the rear drive axle.

[0101] The calculated actual speed difference is compared with the preset speed difference threshold. If the actual speed difference is less than or equal to the speed difference threshold, the vehicle is determined to be in a stable driving state, and a feedback torque correction command with a value of zero is generated. If the actual speed difference is greater than the speed difference threshold, it is determined that the drive axle is slipping, and the feedback correction amount calculation process is entered.

[0102] Based on the amount by which the actual speed difference exceeds the speed difference threshold, a preset proportional-integral control algorithm is used to calculate the feedback torque correction amount used to eliminate the speed difference, and the feedback torque correction amount is assigned to the feedback torque correction command.

[0103] Specifically, by continuously collecting wheel dynamic signals from four wheel speed sensors, the average rotational speeds of the front and rear drive axles are calculated, specifically the average rotational speed n of the front drive axle. front The speed n of the left front wheel fl With the right front wheel speed n fr The average speed n of the rear drive axle was calculated. rear The speed n of the left rear wheel rl With the right rear wheel speed n rr The calculation is as follows:

[0104]

[0105] Then, the actual speed difference Δn between the front and rear drive axles is calculated:

[0106] Δn=|n front -n rear |;

[0107] This speed difference Δn is the direct basis for judging whether there is relative slippage between the front and rear axles;

[0108] Then, the calculated actual speed difference Δn is compared with a preset speed difference threshold Δn. threshold The comparison is performed, and the threshold is determined by calibration. Its value must be able to effectively distinguish between the small speed difference during normal turning and the large speed difference caused by slippage.

[0109] If Δn≤Δn threshold If the vehicle is in a stable driving state, no feedback correction is needed. In this case, the system generates a feedback torque correction command T with a value of zero. corr_fb That is, T corr_fb=0, which means that the final torque distribution will be entirely determined by the aforementioned feedforward command;

[0110] If Δn>Δn threshold If slippage is detected, it is determined that a drive axle is slipping (for example, the average speed of the front axle is significantly higher than that of the rear axle, indicating insufficient adhesion of the front axle). At this time, the system immediately enters the feedback correction calculation process to calculate the excess amount e of the actual speed difference exceeding the threshold.

[0111] e = Δn - Δn threshold ;

[0112] This excess amount e is used as the control deviation and input to a preset proportional-integral controller. The goal of this controller is to make the control deviation e approach zero, that is, to eliminate the abnormal speed difference.

[0113] The calculation formula for the proportional-integral control algorithm is:

[0114] T corr_fb =K p e+K i ·∫e dt;

[0115] Among them, K p The proportional gain determines how quickly the system responds to the current deviation, K. i ∫e dt is the integral gain, used to eliminate steady-state error and ensure that the speed difference can be completely corrected; ∫e dt is the integral of the control deviation over time.

[0116] The calculated T corr_fb This refers to the feedback torque correction amount. The physical meaning of this correction amount is usually the proportion of torque or equivalent pressure that needs to be additionally allocated to the low-speed drive axle (or reduced from the high-speed drive axle). Ultimately, this T... corr_fb Assign the value to the feedback torque correction command.

[0117] The feedforward torque distribution reference command and the feedback torque correction command are superimposed to generate the final total torque distribution command. The total torque distribution command is then sent to the actuator of the central differential to control the clamping force of the multi-plate clutch of the central differential and execute the inter-shaft torque distribution.

[0118] Furthermore, the final process for generating the total torque distribution command includes:

[0119] Verify the signal validity of the feedforward torque distribution reference command and the feedback torque correction command;

[0120] Both the effective feedforward torque distribution reference command and the feedback torque correction command are subjected to amplitude limiting processing based on a preset output range.

[0121] The feedforward torque distribution reference command after the amplitude limiting process is algebraically added to the feedback torque correction command to obtain an initial total torque distribution command.

[0122] The initial total torque distribution command is input to a first-order low-pass filter for smoothing to suppress high-frequency jitter in the command.

[0123] The smoothed command is used as the final total torque distribution command and sent to the actuator of the center differential.

[0124] Specifically, it receives the feedforward torque distribution reference command T from the feedforward channel. bias-ff and feedback torque correction command T from the feedback channel corr_fb To ensure the robustness of the system, the validity of the two input commands is first checked. This check includes, but is not limited to, checking whether the signal value is within the physically possible range, checking whether the signal has changed, and determining whether the signal source has reported a communication failure. If either command is determined to be invalid, the system can adopt a safety strategy, such as using the valid value from the previous moment or using a default safe value as a substitute.

[0125] Subsequently, the commands that passed the validity check were subjected to amplitude limiting based on a preset output range. Feedforward torque distribution reference command T bias-ff Limited to a preset range [T] ff-min ,T ff-max Within, feedback torque correction command T corr_fb Limited to a preset range [T] fb-min ,T fb-max Within this step, the aim is to prevent the final instruction from exceeding the physical actuation capability of the actuator due to a calculation anomaly in any single channel. The calculation formula is as follows:

[0126] T bias_ff_limited =min(max(T) bias_ff ,T ff_min ),T ff_max );

[0127] T corr_fb_limited =min(max(T) corr_fb ,T fb_min ),T fb_max );

[0128] After the amplitude limiting is completed, the two processed commands are algebraically added to obtain an initial total torque distribution command T. bias_initial :

[0129] T bias_initial =T bias_ff_limited +T corr_fb_limited ;

[0130] Subsequently, the initial total torque distribution command T will be executed. bias_initial The input is smoothed by a first-order low-pass filter. The discretization formula for this filter can be expressed as:

[0131] T bias_final (k)=α·T bias_initial (k)+(1-α)·T bias_final (k-1);

[0132] Among them, T bias_initial (k) is the final output instruction at time k, T bias_final (k-1) is the final output command at the previous moment, and α is the filter coefficient (0<α≤1), the value of which is determined according to the required filter cutoff frequency and system sampling time. This filtering process can effectively suppress high-frequency command jitter caused by road excitation or sensor noise, avoid frequent operation of the multi-plate clutch and its actuator of the central differential, thereby improving smoothness, durability and reducing noise;

[0133] Finally, the smoothed T bias_final As the final total torque distribution command, it is sent to the actuator of the central differential via the vehicle bus (such as the CAN bus). The actuator (usually an electro-hydraulic valve or motor) linearly adjusts the clamping force of the multi-plate clutch according to the received command value, thereby precisely controlling the torque ratio distributed between the front and rear drive axles and realizing intelligent dynamic distribution of torque between the axles.

[0134] It can detect in real time whether individual wheels are slipping. If it does, it sends a wheel-to-wheel slip limiting coordination request to the electronic stability program controller.

[0135] Furthermore, the process for sending the inter-wheel limited-slip coordination request includes:

[0136] Based on the collected wheel dynamic signals, the wheel speed difference between two wheels on the same drive axle is calculated in real time and compared with a first preset threshold. At the same time, the slip ratio of a single wheel is calculated and compared with a second preset threshold.

[0137] If the wheel speed difference continues to exceed the first preset threshold, and / or the slip ratio continues to exceed the second preset threshold and reaches a preset duration, then it is determined that individual wheels on the drive axle are slipping.

[0138] When a comprehensive assessment indicates slippage, the identification of the slipping wheel is used as the target slipping wheel identification, and the intervention request level is determined based on the magnitude of the slippage rate.

[0139] Based on the target slipping wheel identifier and the requested intervention level obtained from the slipping state parameterization, an inter-wheel slip limiting coordination request is generated.

[0140] The generated inter-wheel limited-slip coordination request is sent to the electronic stability program controller via the controller area network bus.

[0141] Specifically, by continuously monitoring wheel dynamic signals and performing real-time diagnosis based on dual criteria, the system accurately identifies individual wheel slippage. For two wheels on the same drive axle, the wheel speed difference is calculated; for example, for the front drive axle, the wheel speed difference Δn... wheel The calculation formula is: Δn wheel =|n fl -n fr |;

[0142] Where, n fl and n fr Let the rotational speeds of the left and right front wheels be the values, and calculate the speed difference Δn between these wheels. wheel With a preset first threshold Δn wheel,th The threshold is used to identify whether there is a significant difference in rotational speed between the wheels on both sides of the same axle.

[0143] Simultaneously, the system calculates the slip ratio s of a single wheel. The formula for calculating the slip ratio s is:

[0144]

[0145] Among them, v vehicle For reference vehicle speed, ω can be estimated from the speed of non-driving wheels or information from inertial sensors. wheel Let r be the angular velocity of the wheel. dynamic Given the dynamic rolling radius of the wheel, the calculated slip ratio s is compared with a preset second threshold s. th This threshold is used to determine whether the degree of slippage of a single wheel relative to the ground has exceeded the normal range.

[0146] To prevent momentary misjudgments caused by road bumps or sensor noise, a persistence condition is introduced, which applies only when the aforementioned wheel speed difference Δn is reached. wheel The slip ratio s continuously exceeds a first preset threshold and / or continuously exceeds a second preset threshold, and this exceeding state is maintained for a preset duration T. hold (For example, after 200 milliseconds), the system makes a comprehensive judgment that individual wheels on the drive axle have indeed slipped;

[0147] When a slippage is detected by the comprehensive assessment, the system immediately parameterizes the slippage state to provide accurate information for subsequent coordinated control. The system identifies the wheel that generates the maximum slip ratio or causes a difference in wheel speed, and determines its identity (such as the left front wheel or the right rear wheel) as the target slipping wheel identifier. Based on the calculated slip ratio s, it maps it to a predefined request intervention level, which can be set as follows:

[0148] Low-level intervention, when s th <When s ≤ s1, medium-level intervention; when s1 < s ≤ s2, high-level intervention; when s > s2, the intervention level can correspond to the target braking torque range required by the ESC system. Subsequently, the above parameterized results, namely the target slipping wheel identifier and the requested intervention level, are encapsulated into a structured inter-wheel limited-slip cooperation request message, and then, through the controller area network bus, the generated inter-wheel limited-slip cooperation request message is sent to the electronic stability program controller, and this message triggers the ESC controller to enter the cooperation working mode to prepare for subsequent precise braking intervention on the specified wheel.

[0149] Receive the wheel braking state information fed back by the electronic stability program controller for the inter-wheel limited-slip cooperation request, and based on this information, maintain or adjust the total torque distribution instruction to cooperate in guiding the driving torque to the wheel with the best adhesion conditions.

[0150] Furthermore, the process of maintaining or adjusting the total torque distribution instruction includes:

[0151] Analyze the wheel braking state information to obtain the actual braking pressure of the braked wheel;

[0152] Compare the actual braking pressure with the requested intervention level in the inter-wheel limited-slip cooperation request to evaluate the actual braking intervention effect of the electronic stability program controller;

[0153] If the evaluation result shows that the actual braking intervention effect has reached the expectation, maintain the current total torque distribution instruction; if the evaluation result shows that the actual braking intervention effect has not reached the expectation, then correct the total torque distribution instruction based on the difference between the actual braking pressure and the expected braking pressure;

[0154] Take the maintained or corrected total torque distribution instruction as the new control reference and output it to the actuator of the central differential.

[0155] After sending the inter-wheel limited-slip cooperation request to the electronic stability program controller, the system continuously monitors the controller area network bus, waits for and receives the feedback information from the ESC controller, that is, the wheel braking state information. This information is usually a data frame, which contains the actual braking wheel cylinder pressure value P of the requested braked wheel brake_actual , and by analyzing this data frame, obtain the actual braking pressure P of the braked wheel brake_actual , and then conduct an evaluation of the braking intervention effect. This process compares the actual braking effect with the expected effect. Specifically, according to the previously sent requested intervention level, query a pre-set mapping table to obtain a corresponding expected braking pressure range [P expected_min , P expected_maxFor example, a low-level intervention may correspond to a lower range of expected stress, while a high-level intervention may correspond to a higher range of expected stress.

[0156] If the evaluation results indicate that the actual braking intervention effect has met the expectations, then the condition is satisfied:

[0157] P brake_actual ≥P expected_min ;

[0158] This indicates that the ESC system has effectively braked the slipping wheel, creating sufficient driving conditions for the wheel with traction on its coaxial side. At this point, the system determines that the current inter-axle torque distribution is effective, and therefore decides to maintain the current total torque distribution command. If the evaluation results indicate that the actual braking intervention effect does not meet the expectations, then the condition is satisfied.

[0159] P brake_actual <P expected_min ;

[0160] This indicates that, for some reason (such as a delayed braking system response or hydraulic limitation), the ESC failed to provide sufficient braking force to completely suppress the slipping wheels. At this point, the system determines that the central differential needs to provide stronger compensation, and therefore decides to modify the total torque distribution command.

[0161] The system calculates the difference ΔP between the actual braking pressure and the expected lower limit of the braking pressure:

[0162] ΔP=P expected-min -P brake -actual ;

[0163] Based on this difference ΔP, a torque distribution correction increment ΔT is calculated using a preset compensation strategy (such as a proportional relationship or a lookup table method). bias The direction of this correction increment is to further reduce the torque distribution ratio to the drive axle containing the slipping wheel. For example, if the front axle wheels are slipping and there is insufficient braking, then ΔT bias A negative value means that more torque needs to be distributed to the rear axle; the corrected total torque distribution command T bias_corrected for:

[0164] T bias_corrected =T bias_final +ΔT bias ;

[0165] Finally, the system will maintain T bias_final or modified T bias_correctedAs a new control benchmark, the actuator output to the central differential achieves closed-loop coordination with the ESC controller through dynamic adjustment based on the actual braking effect of ESC. Together, they ensure that the drive torque can bypass the slip point and be forcibly guided to the wheel with the best adhesion, thus achieving true global torque optimization.

[0166] The system monitors and estimates the real-time temperature of the multi-plate clutch in the central differential under slipping conditions. It compares the real-time temperature with a preset first temperature threshold and a higher second temperature threshold. If the real-time temperature is higher than the first temperature threshold but lower than the second temperature threshold, predictive thermal management control is executed. If the real-time temperature reaches or exceeds the second temperature threshold, a system protection strategy is executed.

[0167] Furthermore, the execution process of predictive thermal management control includes:

[0168] Based on the total torque distribution command, the clamping force of the multi-plate clutch, and the actual speed difference between the front and rear drive axles, the slipping power consumed by the multi-plate clutch in the slipping state is calculated.

[0169] Based on real-time temperature and the slippage power of the multi-plate clutch, the temperature rise trend is predicted.

[0170] An engine torque limit is calculated based on how close the temperature rise trend is to the first temperature threshold.

[0171] Send a torque limit request containing the engine torque limit amount to the engine controller to reduce the input torque delivered to the center differential at the source;

[0172] With engine torque limited, the total torque distribution command is simultaneously optimized to reduce the torque distribution ratio to the drive axle that is currently slipping, thereby further reducing the slippage work of the multi-plate clutch.

[0173] The system continuously monitors the real-time temperature. If the real-time temperature drops below the first temperature threshold and stabilizes, the torque limiting request is released and the normal torque distribution logic is restored.

[0174] Furthermore, the execution process of the system protection strategy includes:

[0175] A forced command is generated and sent to the actuator of the central differential to reduce the clamping force of the multi-plate clutch to a preset minimum safety value, so as to cut off or significantly reduce the power transmission to the rear drive axle and put the vehicle into front-wheel drive mode.

[0176] A high temperature fault alarm signal is generated, and visual and / or auditory warning information is output to the driver through the instrument cluster, indicating that the four-wheel drive system is temporarily limited in function due to overheating.

[0177] Lock the control state of the central differential in the front-wheel drive mode and continuously monitor the real-time temperature until the real-time temperature drops below a preset third temperature recovery threshold;

[0178] When the real-time temperature drops below the third temperature recovery threshold,解除系统状态锁定,并按照预设的恢复速率,逐步恢复多片离合器的压紧力与正常的扭矩分配控制逻辑。

[0179] Specifically, through a preset temperature model or a direct temperature sensor signal, continuously monitor and estimate the real-time temperature T of the multi-plate clutch in the central differential under the slip state clutch , compare this real-time temperature with two preset temperature thresholds, the first temperature threshold T1 (warning threshold) and the higher second temperature threshold T2 (protection threshold);

[0180] When it is determined that T1 < T clutch < T2, it indicates that the clutch temperature is already relatively high and there is a risk of overheating. The system immediately executes predictive thermal management control. Specifically, based on the current total torque distribution command T bias_final (which reflects the torque to be transmitted), the current pressing force F of the multi-plate clutch clamp and

[0181] the actual rotational speed difference Δn between the front and rear drive axles, calculate the slip power P consumed by the multi-plate clutch slip , and its calculation formula is:

[0182] P slip = k·min(F clamp ·μ, T bias_final );

[0183] where k is a proportionality coefficient and μ is the friction coefficient, and this power directly reflects the heat generation;

[0184] Based on the current real-time temperature T clutch and the calculated slip power P slip , predict the temperature rise trend ΔT of the clutch in the next short period through a simplified thermal model (for example, considering the heat capacity and heat dissipation capacity of the clutch) pred , according to the predicted temperature rise trend ΔT pred and its proximity to the first temperature threshold T1, calculate an engine torque limit T engine_limit , and the calculation logic is that the faster the predicted temperature rise and the higher the current temperature, the greater the requested torque limit, aiming to reduce the energy input from the source;

[0185] The system sends T engine_limitThe torque limit request, synchronously, the system optimizes the total torque distribution instruction, strategically reducing the torque distribution ratio to the drive axle that is currently in a slipping state. For example, if the front axle slips, the instruction is more biased towards rear-wheel drive, thus directly reducing the torque and sliding friction work that the multi-plate clutch needs to transmit, reducing the heat load from within the system, by continuously monitoring T clutch , when T clutch drops below T1 and remains stable, it is considered that the heat risk has been lifted, and then the torque limit request sent to the engine controller is lifted, and the normal torque distribution control logic is restored;

[0186] When it is determined that T clutch ≥T2, it indicates that the clutch is in a severely overheated state. The system immediately executes the highest-level system protection strategy. Specifically, the system generates and sends a forced instruction to the actuator of the central differential, ordering it to reduce the pressing force F clamp of the multi-plate clutch to a preset minimum safety value F min . This operation aims to cut off or significantly reduce the power transmission to the rear drive axle, making the vehicle substantially enter the front-wheel drive mode, thus completely stopping the heat generation due to the sliding friction of the multi-plate clutch;

[0187] At the same time, the system generates a high-temperature fault warning signal and sends it to the combination meter via the CAN bus. The meter outputs visual and / or audible warning information to the driver by lighting a specific warning light and / or displaying a prompt message, clearly indicating that the four-wheel drive system is temporarily functionally limited due to overheating. The system locks the control state of the central differential in the front-wheel drive mode, preventing the clutch from being re-engaged due to the intervention of other control logics during this period. At the same time, continuously monitor T clutch , until it drops below a preset third temperature recovery threshold T3 to ensure that the clutch is fully cooled. When T clutch <T3, the system releases the state lock. Subsequently, instead of immediately restoring full functionality, it gradually increases the pressing force of the multi-plate clutch at a preset, slow recovery rate and synchronously restores the normal torque distribution control logic. This progressive recovery avoids a rapid resurgence of temperature and ensures the durability of the system.

[0188] Example 2:

[0189] Existing technologies relying on reactive feedback control mechanisms have inherent flaws. The most prominent problem is the system response delay, leading to insufficiently timely and smooth traction and stability control under complex conditions. Specifically, there is a significant time lag from the occurrence of slippage to its detection and the completion of torque redistribution. During rapid acceleration or high-speed cornering on low-traction surfaces, this delay can cause momentary power interruption, continuous wheel spin, and even affect vehicle dynamic stability. Furthermore, this system typically operates independently, lacking sufficient coordination with other vehicle electronic control systems (such as electronic stability programs), making it difficult to achieve optimal utilization of traction at the vehicle level. To address these issues, this invention provides a dynamic adjustment system for the central differential based on torque distribution optimization, the structure of which is as follows: Figure 2 As shown. The specific implementation process of this system is as follows:

[0190] The state perception and prediction module is used to collect the vehicle's drive demand signal, vehicle dynamic signal and wheel dynamic signal. Based on the drive demand signal, vehicle dynamic signal and wheel dynamic signal, it predicts the vehicle's driving state trend and the load change trend of the front and rear drive axles at the next moment through a preset vehicle dynamics model, and obtains and outputs the feedforward torque distribution reference command.

[0191] The feedback correction module is used to calculate the actual speed difference between the front and rear drive axles in real time based on the wheel dynamic signals, compare the actual speed difference with the preset speed difference threshold, and generate feedback torque correction commands.

[0192] The torque distribution synthesis module is used to superimpose the feedforward torque distribution reference command and the feedback torque correction command to generate the final total torque distribution command, and send the total torque distribution command to the actuator of the central differential to control the clamping force of the multi-plate clutch of the central differential and execute the inter-shaft torque distribution.

[0193] The wheel-to-wheel coordination decision module is used to determine in real time whether individual wheels are slipping. If the determination is yes, it sends a wheel-to-wheel limited-slip coordination request to the electronic stability program controller.

[0194] The wheel-to-wheel coordination execution module is used to receive wheel braking status information from the electronic stability program controller in response to the wheel-to-wheel limited-slip coordination request, and based on this information, maintain or adjust the total torque distribution command to coordinate the drive torque to the wheel with the best adhesion conditions.

[0195] The thermal management protection module is used to monitor and estimate the real-time temperature of the multi-plate clutch in the central differential under slipping conditions. It compares the real-time temperature with a preset first temperature threshold and a higher second temperature threshold. If the real-time temperature is higher than the first temperature threshold but lower than the second temperature threshold, predictive thermal management control is executed. If the real-time temperature reaches or exceeds the second temperature threshold, a system protection strategy is executed.

[0196] Specifically, the state perception and prediction module predicts vehicle state and inter-axle load changes through the vehicle dynamics model and outputs a feedforward torque distribution baseline command. At the same time, the feedback correction module monitors the inter-axle speed difference in real time and generates a feedback torque correction command accordingly. Subsequently, the torque distribution synthesis module integrates and optimizes the above feedforward and feedback commands to generate the final total torque distribution command, which drives the central differential actuator to complete the basic inter-axle torque distribution. If the wheel coordination decision module detects individual wheel slippage, it immediately sends a coordination request to the electronic stability program controller, and the wheel coordination execution module dynamically adjusts the total torque distribution command based on the braking state information it receives, thereby achieving global torque optimization for inter-axle and wheel coordination. The thermal management protection module monitors the multi-plate clutch temperature in real time and executes predictive thermal management or system protection strategies in stages to ensure that the system has extremely high reliability and durability while operating efficiently.

[0197] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A dynamic adjustment method for a central differential based on torque distribution optimization, characterized in that, Includes the following steps: The system collects the vehicle's drive demand signal, vehicle dynamic signal, and wheel dynamic signal. Based on the drive demand signal, vehicle dynamic signal, and wheel dynamic signal, it uses a preset vehicle dynamics model to predict the vehicle's driving state trend and the load change trend of the front and rear drive axles at the next moment, and obtains and outputs the feedforward torque distribution reference command. Based on wheel dynamic signals, the actual speed difference between the front and rear drive axles is calculated in real time, and the actual speed difference is compared with a preset speed difference threshold to generate a feedback torque correction command. The feedforward torque distribution reference command and the feedback torque correction command are superimposed to generate the final total torque distribution command, and the total torque distribution command is sent to the actuator of the central differential to control the clamping force of the multi-plate clutch of the central differential and perform inter-shaft torque distribution. It can detect in real time whether individual wheels are slipping. If it does, it sends a wheel-to-wheel slip limiting coordination request to the electronic stability program controller. The system receives wheel braking status information from the electronic stability program controller in response to the wheel-to-wheel limited-slip coordination request, and maintains or adjusts the total torque distribution command based on this information to coordinate the direction of drive torque to the wheel with the best traction conditions. The system monitors and estimates the real-time temperature of the multi-plate clutch in the central differential under slipping conditions. The real-time temperature is compared with a preset first temperature threshold and a higher second temperature threshold. If the real-time temperature is higher than the first temperature threshold but lower than the second temperature threshold, predictive thermal management control is executed. If the real-time temperature reaches or exceeds the second temperature threshold, a system protection strategy is executed.

2. The method for dynamic adjustment of a central differential based on torque distribution optimization according to claim 1, characterized in that, The process for obtaining the feedforward torque distribution reference command includes: The driving demand signal, vehicle dynamic signal and wheel dynamic signal are acquired in real time, and the signals are filtered and validated to obtain the vehicle state parameter set at the current moment. The current vehicle state parameter set is input into the preset vehicle dynamics model. By calculating the vehicle's longitudinal and lateral dynamic equations, the longitudinal acceleration, lateral acceleration, and yaw rate trends of the vehicle in the next sampling period are predicted. Based on the predicted longitudinal acceleration and lateral acceleration trends, and combined with preset vehicle mass parameters and wheelbase and track parameters, the dynamic load transfer of the front and rear drive axles caused by the inertial force generated by vehicle acceleration and deceleration and the centrifugal force generated by vehicle steering is calculated. Based on the dynamic load transfer amount and according to the principle that the drive axle with increased load can obtain greater drive torque, a feedforward torque distribution reference command for optimizing vehicle traction and stability at the next moment is calculated.

3. The method for dynamic adjustment of a central differential based on torque distribution optimization according to claim 2, characterized in that, The prediction process for the longitudinal acceleration change trend, lateral acceleration change trend, and yaw rate change trend includes: Based on the throttle opening and current vehicle speed in the drive demand signal, the expected driving force of the vehicle is calculated using a preset engine torque MAP and transmission system model. Based on the current vehicle speed and the preset vehicle driving resistance model, the driving resistance experienced by the vehicle is calculated. Based on the difference between the expected driving force and the driving resistance, combined with the preset vehicle mass, the longitudinal acceleration change trend in the next sampling period is estimated by calculating using Newton's second law. Based on the steering wheel angle in the vehicle dynamic signal, the lateral force acting on the front wheels of the vehicle is calculated using a preset steering system transmission ratio and a vehicle tire lateral slip characteristic model. Based on the lateral force of the front wheel, the current vehicle speed, and the preset vehicle center of gravity position and moment of inertia parameters, the lateral acceleration and yaw rate trends in the next sampling period are simultaneously estimated using a two-degree-of-freedom bicycle model.

4. The method for dynamic adjustment of a central differential based on torque distribution optimization according to claim 1, characterized in that, The process for generating the feedback torque correction command includes: Based on the collected wheel dynamic signals, the average speed of the front drive axle and the average speed of the rear drive axle are calculated respectively. The actual speed difference between the front and rear drive axles is calculated based on the average speed of the front drive axle and the average speed of the rear drive axle. The calculated actual speed difference is compared with a preset speed difference threshold. If the actual speed difference is less than or equal to the speed difference threshold, the vehicle is determined to be in a stable driving state, and a feedback torque correction command with a value of zero is generated. If the actual speed difference is greater than the speed difference threshold, it is determined that the drive axle is slipping, and the feedback correction amount calculation process is entered. Based on the amount by which the actual speed difference exceeds the speed difference threshold, a feedback torque correction amount for eliminating the speed difference is calculated using a preset proportional-integral control algorithm, and the feedback torque correction amount is assigned to the feedback torque correction command.

5. The method for dynamic adjustment of a central differential based on torque distribution optimization according to claim 1, characterized in that, The process for generating the final total torque distribution command includes: The signal validity of the feedforward torque distribution reference command and the feedback torque correction command is verified. The effective feedforward torque distribution reference command and the feedback torque correction command are respectively subjected to amplitude limiting processing based on a preset output range; The feedforward torque distribution reference command after amplitude limiting is algebraically added to the feedback torque correction command to obtain an initial total torque distribution command. The initial total torque distribution command is input to a first-order low-pass filter for smoothing to suppress high-frequency jitter in the command. The smoothed command is used as the final total torque distribution command and sent to the actuator of the center differential.

6. The method for dynamic adjustment of a central differential based on torque distribution optimization according to claim 1, characterized in that, The process for sending the inter-wheel limited-slip coordination request includes: Based on the collected wheel dynamic signals, the wheel speed difference between two wheels on the same drive axle is calculated in real time and compared with a first preset threshold. At the same time, the slip ratio of a single wheel is calculated and compared with a second preset threshold. If the wheel speed difference continues to exceed the first preset threshold, and / or the slip ratio continues to exceed the second preset threshold and reaches a preset duration, then it is determined that individual wheels on the drive axle are slipping. When a slippage is detected by comprehensive assessment, the identification of the slipping wheel is determined as the target slipping wheel identification, and the intervention request level is determined based on the magnitude of the slippage rate. Based on the target slipping wheel identifier and the requested intervention level obtained from the slipping state parameterization, an inter-wheel slip limiting coordination request is generated. The generated inter-wheel limited-slip coordination request is sent to the electronic stability program controller via the controller area network bus.

7. The method for dynamic adjustment of a central differential based on torque distribution optimization according to claim 1, characterized in that, The process for maintaining or adjusting the total torque distribution command includes: Analyze the wheel braking status information to obtain the actual braking pressure of the braked wheel; The actual braking pressure is compared with the requested intervention level in the wheel-to-wheel limited-slip coordination request to evaluate the actual braking intervention effect of the electronic stability program controller. If the evaluation results indicate that the actual braking intervention effect has met expectations, the current total torque distribution command is maintained. If the evaluation results indicate that the actual braking intervention effect has not met expectations, the total torque distribution command is modified based on the difference between the actual braking pressure and the expected braking pressure. The maintained or modified total torque distribution command is used as the new control reference and output to the actuator of the center differential.

8. The method for dynamic adjustment of a central differential based on torque distribution optimization according to claim 1, characterized in that, The execution process of the predictive thermal management control includes: Based on the total torque distribution command, the clamping force of the multi-plate clutch, and the actual speed difference between the front and rear drive axles, calculate the slipping power consumed by the multi-plate clutch in the slipping state; Based on the real-time temperature and the slippage power of the multi-plate clutch, the temperature rise trend is predicted. Based on how close the temperature rise trend is to the first temperature threshold, an engine torque limit is calculated. Send a torque limit request containing the engine torque limit amount to the engine controller to reduce the input torque transmitted to the center differential from the source; With engine torque limited, the total torque distribution command is simultaneously optimized to reduce the torque distribution ratio to the drive axle that is currently slipping, thereby further reducing the slippage work of the multi-plate clutch. The real-time temperature is continuously monitored. If the real-time temperature drops below the first temperature threshold and stabilizes, the torque limiting request is released and the normal torque distribution logic is restored.

9. The method for dynamic adjustment of a central differential based on torque distribution optimization according to claim 1, characterized in that, The execution process of the system protection strategy includes: A forced command is generated and sent to the actuator of the central differential to reduce the clamping force of the multi-plate clutch to a preset minimum safety value, so as to cut off or significantly reduce the power transmission to the rear drive axle and put the vehicle into front-wheel drive mode. A high temperature fault alarm signal is generated, and visual and / or auditory warning information is output to the driver through the instrument cluster, indicating that the four-wheel drive system is temporarily limited in function due to overheating. The control state of the central differential is locked in the front-wheel drive mode, and the real-time temperature is continuously monitored until the real-time temperature drops below a preset third temperature recovery threshold. When the real-time temperature drops below the third temperature recovery threshold, the system state lock is released, and the clamping force of the multi-plate clutch and the normal torque distribution control logic are gradually restored according to the preset recovery rate.

10. A dynamic adjustment system for a central differential based on torque distribution optimization, characterized in that, A method for dynamic adjustment of a center differential based on torque distribution optimization as described in any one of claims 1-9, the system comprising the following modules: The state perception and prediction module is used to collect the vehicle's driving demand signal, vehicle dynamic signal and wheel dynamic signal. Based on the driving demand signal, vehicle dynamic signal and wheel dynamic signal, the module predicts the driving state trend of the vehicle and the load change trend of the front and rear drive axles at the next moment through a preset vehicle dynamics model, and obtains and outputs the feedforward torque distribution reference command. The feedback correction module is used to calculate the actual speed difference between the front and rear drive axles in real time based on the wheel dynamic signal, compare the actual speed difference with a preset speed difference threshold, and generate a feedback torque correction command. The torque distribution synthesis module is used to superimpose the feedforward torque distribution reference command and the feedback torque correction command to generate the final total torque distribution command, and send the total torque distribution command to the actuator of the central differential to control the clamping force of the multi-plate clutch of the central differential and perform inter-shaft torque distribution. The wheel-to-wheel coordination decision module is used to determine in real time whether individual wheels are slipping. If the determination is yes, it sends a wheel-to-wheel limited-slip coordination request to the electronic stability program controller. The inter-wheel coordination execution module is used to receive wheel braking status information from the electronic stability program controller in response to the inter-wheel limited slip coordination request, and maintain or adjust the total torque distribution command based on the information to coordinate the drive torque to the wheel with the best adhesion conditions. The thermal management protection module is used to monitor and estimate the real-time temperature of the multi-plate clutch in the central differential under slipping conditions. The real-time temperature is compared with a preset first temperature threshold and a higher second temperature threshold. If the real-time temperature is higher than the first temperature threshold but lower than the second temperature threshold, predictive thermal management control is executed. If the real-time temperature reaches or exceeds the second temperature threshold, a system protection strategy is executed.

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