Smoothness optimization control method for AMT clutch disengagement rate

Abstract

The present application relates to the technical field of automatic transmission control of vehicles, and discloses a smoothness optimization control method for AMT clutch separation rate. The method acquires input signals such as current engine speed, engine idle speed, current engine torque, clutch feedback torque, engine speed change rate, slope, turning radius, current gear, theoretically calculated starting gear, brake signal and clutch target torque, respectively calculates a first separation rate based on the slope and the turning radius and a second separation rate based on the current engine torque and the clutch feedback torque, takes the smaller value of the two as the initial output separation rate in the low-speed driving condition, and determines the final separation rate in combination with anti-reverse drag protection, anti-flameout protection, neutral gear condition control and separation stroke end control, so as to improve the jerk and reverse drag impact of the AMT vehicle in the low-speed non-gear shifting condition and improve the driving smoothness and comfort.

Description

Technical Field

[0001] This invention relates to the field of vehicle automatic transmission control technology, and in particular to a method for optimizing the smoothness of clutch disengagement rate in low-speed, non-shifting conditions of an electromechanical automatic transmission (AMT). Background Technology

[0002] Electromechanical automatic transmissions (AMTs) combine the high transmission efficiency of manual transmissions with the convenience of automatic control, and have been widely used in the commercial vehicle sector. As the demands for low-speed drivability, smoothness, and comfort in vehicles continue to increase, the control quality of AMTs in non-shifting conditions such as urban congestion, low-speed crawling, coasting, and deceleration after releasing the accelerator pedal is gradually becoming a crucial factor affecting user experience and overall vehicle dynamics. Under these conditions, the vehicle's kinetic energy is low, the system inertia is relatively small, and the torsional elasticity and torque fluctuations of the transmission system are more easily transmitted to the entire vehicle. When the driver releases the accelerator pedal to coast or decelerate, if the clutch disengagement is not properly controlled, the transition from engagement to disengagement of the powertrain can easily become uneven, resulting in problems such as vehicle jerking, increased impact, abrupt deceleration, or significant engine drag.

[0003] In existing technologies, clutch control for low-speed driving conditions generally falls into two categories. One is a closed-loop control method based on clutch torque transmission. By setting upper and lower torque limits, the clutch is maintained within a certain semi-engaged range, thus controlling engagement or disengagement. While this approach can address torque transmission needs at low speeds to some extent, its core focus is on maintaining the semi-engaged state rather than precisely calculating the clutch disengagement rate. Therefore, when faced with scenarios involving multiple coupled factors such as inclines, steering, engine deceleration changes, and the risk of back-dragging, it often struggles to accurately output a disengagement rate better suited to the current situation. The other approach emphasizes condition identification and strategy switching. It identifies the current vehicle situation using information such as engine speed, torque, throttle signal, braking signal, and shift requests, and then selects the appropriate strategy from several preset disengagement strategies. Such solutions can cover a variety of operating conditions, but they usually remain at the macro-control level of identifying operating conditions and selecting strategies. The specific adjustments made to the clutch disengagement rate under specific operating conditions based on parameters such as slope, turning radius, feedback torque, engine speed difference, and engine speed change rate are not disclosed in sufficient depth.

[0004] Furthermore, existing engineering control methods commonly employ a pre-calibrated fixed clutch disengagement rate. While simple to implement, this method has limited adaptability to complex operating conditions. At low gears, low speeds, and low inertia, due to the large transmission ratio and significant torque amplification effect, the powertrain is more sensitive to clutch disengagement. If the disengagement rate is set too high, it can easily lead to abrupt powertrain engagement and disengagement, causing vehicle impact and jerking. Conversely, if the disengagement rate is set too low, or the engagement time is too long, the engine's reverse torque will be transmitted to the wheels more quickly, causing rapid vehicle deceleration, and in severe cases, even causing the engine speed to drop too quickly or stall. Therefore, current technology still lacks a control method for low-speed, non-shifting conditions that can comprehensively consider external environmental factors, powertrain status, protection boundaries, and disengagement end control requirements, and output a refined clutch disengagement rate. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a smoothness optimization control method for the clutch disengagement rate of an AMT vehicle, so as to solve the problems of jerking, back drag shock and increased risk of stalling caused by improper clutch disengagement rate control in AMT vehicles under low-speed non-shifting conditions.

[0006] To solve the above problems, the present invention adopts the following technical solution:

[0007] The method for optimizing the smoothness control of AMT clutch disengagement rate includes the following steps:

[0008] S1. Obtain the input signals required for clutch disengagement rate control. The input signals include at least the current engine speed, engine idle speed, current engine torque, clutch feedback torque, engine speed change rate, slope, turning radius, current gear, theoretically calculated starting gear, braking signal, and clutch target torque.

[0009] S2. Determine the basic clutch disengagement rate based on the slope and turning radius, and correct the basic clutch disengagement rate based on the initial clutch feedback torque. Then, combine the anti-drag protection, anti-stalling protection and neutral mode control in sequence to obtain the first disengagement rate.

[0010] S3. Determine the second basic clutch disengagement rate based on the current engine torque and the clutch feedback torque, and perform dynamic feedback correction based on the speed difference between the current engine speed and the engine idle speed and the engine speed change rate to obtain the second disengagement rate;

[0011] S4. Determine whether the vehicle is in a low-speed driving condition based on the relationship between the current gear and the theoretically calculated starting gear. When in a low-speed driving condition, take the smaller value between the first separation rate and the second separation rate as the initial output separation rate. When not in a low-speed driving condition, take the first separation rate as the initial output separation rate.

[0012] S5. When the preset end control conditions are met, determine the final separation rate at the end of the clutch separation stroke based on the engine speed change rate;

[0013] If the preset end control conditions are not met, the initial output separation rate is taken as the final separation rate.

[0014] Furthermore, in step S1:

[0015] The input signals include CAN bus signals, external sensor signals, and TCU internal signals;

[0016] The CAN bus signals include the current engine speed, engine idle speed, relative wheel speed, and foot brake and handbrake signals.

[0017] The external sensor signals include clutch feedback torque, ramp and gear displacement;

[0018] The internal signals of the TCU include the clutch target torque, engine speed change rate, turning radius, current gear, and theoretically calculated starting gear.

[0019] Furthermore, in step S2, the basic clutch disengagement rate is corrected based on the initial clutch feedback torque, specifically as follows:

[0020] Compare the initial clutch feedback torque with a preset torque threshold;

[0021] When the initial clutch feedback torque is greater than the preset torque threshold, a positive correction value is used to correct the basic clutch disengagement rate, and the absolute value of the positive correction value increases as the initial clutch feedback torque increases.

[0022] When the initial clutch feedback torque is less than the preset torque threshold, a negative correction value is used to correct the basic clutch disengagement rate, and the absolute value of the negative correction value increases as the initial clutch feedback torque decreases.

[0023] Furthermore, the anti-reverse drag protection in step S2 includes:

[0024] When the engine speed change rate is less than the first speed change rate threshold, the speed difference between the current engine speed and the engine idle speed is less than the first speed difference threshold, and the current engine torque is less than the first torque threshold, the anti-reverse drag protection is triggered.

[0025] After the anti-reverse drag protection is triggered, the corrected separation rate is compared with the first protection separation rate, and the larger of the two values ​​is taken as the separation rate after the anti-reverse drag protection.

[0026] Furthermore, the anti-flare protection and neutral mode control in step S2 include:

[0027] When the speed difference between the current engine speed and the engine idle speed is less than the second speed difference threshold, the anti-stalling protection is triggered, and the separation rate after the anti-reverse drag protection is compared with the second protection separation rate. The larger of the two values ​​is taken as the separation rate after the anti-stalling protection, wherein the second protection separation rate is greater than the first protection separation rate.

[0028] When the current gear is neutral, the separation rate after the anti-stalling protection is compared with the neutral separation rate, and the larger of the two values ​​is taken as the first separation rate.

[0029] Furthermore, in step S3, when determining the second basic clutch disengagement rate based on the current engine torque and the clutch feedback torque, the following mapping relationship is satisfied:

[0030] The greater the clutch feedback torque, the greater the disengagement rate of the second basic clutch.

[0031] The lower the current torque of the engine, the greater the disengagement rate of the second basic clutch;

[0032] When the clutch feedback torque is less than the preset torque value, the second basic clutch disengagement rate remains at a small value and no longer changes with the current engine torque.

[0033] Furthermore, the dynamic feedback correction in step S3 includes:

[0034] A first speed change rate threshold, a second speed change rate threshold, and a third speed difference threshold are preset, wherein the second speed change rate threshold is greater than the first speed change rate threshold;

[0035] When the rate of change of engine speed is greater than the first rate of change of engine speed threshold, no dynamic feedback correction is performed;

[0036] When the difference between the current engine speed and the engine idle speed is greater than the third speed difference threshold, and the rate of change of engine speed is greater than the second rate of change of engine speed threshold, no dynamic feedback correction is performed.

[0037] In other cases, dynamic feedback correction is performed, and the dynamic feedback correction value increases as the speed difference decreases and as the rate of change of engine speed decreases.

[0038] Furthermore, in step S4:

[0039] The theoretically calculated starting gear is determined based on the slope and the vehicle's mass through a preset mapping relationship.

[0040] The gear difference between the current gear and the theoretically calculated starting gear is the gear number corresponding to the current gear minus the gear number corresponding to the theoretically calculated starting gear.

[0041] When the gear difference is less than the preset gear offset threshold, or when the current gear is reverse, the vehicle is determined to be in a low-speed driving condition.

[0042] Furthermore, the preset end-point control conditions in step S5 include at least:

[0043] Braking signals indicate that the vehicle has neither a handbrake nor a foot brake;

[0044] The current gear is equal to the theoretically calculated starting gear;

[0045] The difference between the current engine speed and the engine idle speed is greater than the fourth speed difference threshold.

[0046] The clutch target torque is less than the preset first clutch target torque threshold.

[0047] Furthermore, in step S5, when determining the final disengagement rate at the end of the clutch disengagement stroke based on the engine speed change rate, the following relationship is satisfied:

[0048] The smaller the rate of change of engine speed, the greater the final separation rate;

[0049] Furthermore, the maximum value of the final separation rate is less than the initial output separation rate.

[0050] Compared to existing technologies, this invention does not merely maintain a semi-engaged state through a single torque closed loop, nor does it simply switch macroscopic strategies after identifying operating conditions. Instead, it starts with the specific solution process of the clutch disengagement rate, establishing two parallel calculation paths: an environmental path based on slope and turning radius, and a power path based on the engine's current torque and the clutch feedback torque. Under low-speed conditions, it forms a more stable initial output disengagement rate by taking the smaller of the two values. Simultaneously, through anti-drag protection, anti-stalling protection, neutral mode control, and end-of-disengagement re-control, the disengagement action possesses a clear hierarchical and well-constrained rate adjustment mechanism under different risk boundaries. Therefore, on the one hand, the power interruption process is smoother, reducing the impact and jerking during low-speed creep, following other vehicles, and deceleration by releasing the accelerator; on the other hand, it reduces the risk of reverse drag during sudden deceleration and stalling, and further considers slip control under neutral conditions and a delicate transition at the end of the disengagement stage, thereby improving the overall driving smoothness, comfort, and dynamic quality of the vehicle at low speeds. Attached Figure Description

[0051] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0052] Figure 1 A logic flowchart of a smoothness optimization control method for AMT clutch disengagement rate provided in an embodiment of the present invention;

[0053] Figure 2 The graph shows the changes of relevant parameters such as clutch target torque and throttle opening over time under test conditions provided in this embodiment of the invention. Detailed Implementation

[0054] To make the technical solution, implementation process, and achievable effects of this application clearer, the application will be further described below with reference to the accompanying drawings. It should be understood that the following embodiments are only used to illustrate the technical solution of this application and should not be construed as limiting the scope of protection. Where there is no conflict, the technical features in the various embodiments of this application can be combined with each other. For the controller hardware platform, bus communication architecture, sensor installation method, actuator driving method, lookup program calling method, and data exchange method between the vehicle controller and the transmission controller, those skilled in the art can use existing technologies to implement these aspects, as long as they can meet the control requirements of input signal acquisition, logical judgment, and separation rate output described in this application.

[0055] like Figure 1 As shown, the AMT clutch disengagement rate smoothness optimization control method provided in this embodiment does not directly control clutch disengagement using a single path or a fixed rate. Instead, it constrains external environmental factors and power chain state through two parallel paths, selects the results of the two paths under specific operating conditions, and finally refines the control at the end of disengagement, thereby making the entire process of clutch transitioning from the engaged state to the disengaged state more continuous.

[0056] In this embodiment, step S1 is first executed, which involves acquiring the input signals required for clutch disengagement rate control. These input signals include at least the current engine speed, engine idle speed, current engine torque, clutch feedback torque, engine speed change rate, slope, turning radius, current gear, theoretically calculated starting gear, braking signal, and clutch target torque. Further, the input signals can be categorized into CAN bus signals, external sensor signals, and TCU internal signals. The CAN bus signals may include the current engine speed, engine idle speed, relative wheel speeds, and foot and handbrake signals; the external sensor signals may include clutch feedback torque, slope, and gear displacement; and the TCU internal signals may include clutch target torque, engine speed change rate, turning radius, current gear, and theoretically calculated starting gear.

[0057] The relative wheel speed can be used to calculate the turning radius, gear displacement can be used to identify the current gear, and the theoretical starting gear can be obtained based on the slope and vehicle mass through a preset mapping relationship. The acquisition of the slope value, estimation of the vehicle mass, calculation of the turning radius, identification of the current gear, and calculation of the engine speed change rate can be achieved using existing technologies such as sensor detection, bus reading, filtering estimation, or internal controller algorithms; this embodiment does not limit these methods. The purpose of this setup is to enable the control system to simultaneously obtain external road condition information, powertrain status information, driver braking intention information, and clutch control target information before starting to calculate the separation rate, thereby providing a common data foundation for the subsequent two rate calculation paths.

[0058] After acquiring the input signal, this embodiment proceeds to the first separation rate calculation path. This first separation rate calculation path primarily reflects the influence of the vehicle's environment on the clutch disengagement action; therefore, it can be understood as an environmental constraint path. First, the slope value of the current incline of the vehicle is acquired. and the turning radius corresponding to the vehicle's current turning state. The basic clutch disengagement rate is determined based on a preset mapping relationship. The preset mapping relationship is preferably implemented using a two-dimensional lookup table, but can also be implemented using existing technologies such as partition mapping or calibration surfaces. Since the response characteristics of different vehicle models, different vehicle calibration platforms, and different clutch actuators are not entirely the same, the specific calibration values ​​in the two-dimensional lookup table can be set according to the target vehicle model. This embodiment does not limit the specific values ​​in the table one by one. It should be noted that when the slope is large or the turning radius is small, the powertrain is more sensitive to the clutch disengagement action; therefore, the basic clutch disengagement rate... It is not fixed, but varies with the slope value. and turning radius It changes with the external operating conditions. Through this step, a basic starting speed that is more in line with the current driving environment can be given from the perspective of external operating conditions.

[0059] After obtaining the basic clutch disengagement rate Subsequently, this embodiment continues to adjust the basic clutch disengagement rate based on the initial clutch feedback torque. After correction, the separation rate after initial feedback torque correction is obtained. Specifically, the initial clutch feedback torque can be set as follows: And set the preset torque threshold as the torque threshold. The correction value can be obtained using a lookup table method, as is currently known. Correction values ​​can also be obtained using calibration curves or piecewise assignment methods. As an optional embodiment, the torque threshold For example, 400 can be taken; when the initial clutch feedback torque... Greater than the torque threshold At that time, the correction value It is a positive value, and the correction value is... The absolute value varies with the initial clutch feedback torque. Increase and increase; when the initial clutch feedback torque increases Less than the torque threshold At that time, the correction value It is a negative value, and the correction value is... The absolute value varies with the initial clutch feedback torque. Decrease and increase. That is, when the initial clutch load is high, the system appropriately increases the disengagement rate; when the initial clutch load is low, the system appropriately decreases the disengagement rate, to avoid significantly faster or slower disengagement actions before the protection logic is considered. The resulting corrected disengagement rate... It is no longer a basic value determined solely by the environment, but rather a result that takes into account the current stress state of the clutch.

[0060] The corrected separation rate Subsequently, this embodiment continues to implement Level 1 protection to suppress the risk of reverse drag. For ease of explanation, let the speed difference between the current engine speed and the engine idle speed be denoted as the speed difference. Assume the rate of change of engine speed is Assume the current engine torque is Furthermore, a first speed change rate threshold, a first speed difference threshold, and a first torque threshold can be preset. When the engine speed change rate... Less than the first speed change rate threshold, speed difference Less than the first speed difference threshold, and the engine's current torque When the torque is less than the first torque threshold, a significant reverse drag trend is determined, triggering Level 1 protection. After Level 1 protection is triggered, the corrected separation rate will be adjusted. Separation rate from the first protection The larger of the two values ​​is taken as the separation rate after the first-level protection. The control method that uses the larger value is to ensure that the separation rate is not lower than the minimum safety boundary required by the anti-drag protection. In other words, when the separation rate calculated conventionally... When the value is large enough, the result can be directly retained; when the separation rate is obtained through conventional calculation... If the value is too small, then the first protection separation rate will be used. Increase the separation speed to more quickly reduce the engine's drag. For the first protective separation rate... The specific calibration method can be achieved using existing technologies such as discrete calibration or lookup table calibration.

[0061] Following the primary protection, this embodiment further implements secondary protection to suppress the risk of engine stalling. Preferably, a second speed difference threshold can be preset; when the speed difference... When the speed difference is less than the second speed difference threshold, it indicates that the engine's current speed is approaching a higher risk boundary, thus triggering the second-level protection. After the second-level protection is triggered, the second protection separation rate is set. And satisfy the second protection separation rate Greater than the first protection separation rate Subsequently, the separation rate after primary protection was... Separation rate with second protection The larger of the two values ​​is taken as the separation rate after secondary protection. This tiered protection structure allows for the separate handling of anti-towing risks and engine stall risks:

[0062] Level 1 protection primarily ensures that the vehicle will not experience significant sudden deceleration or impact due to engine backdraft;

[0063] The secondary protection further increases the separation rate threshold when the engine speed continues to drop, in order to prevent the engine from being dragged into the shutdown boundary.

[0064] Due to the second protection separation rate Higher than the first protection separation rate Therefore, the effectiveness of secondary protection is higher than that of primary protection. With this setting, the first separation rate path has already undergone four levels of constraints—basic lookup table, feedback torque correction, primary protection, and secondary protection—before reaching neutral control.

[0065] Following the secondary protection, this embodiment also provides separate processing for the neutral gear condition. When the system identifies the current gear as neutral, a neutral disengagement rate is set. and the separation rate after secondary protection Disengagement rate with neutral gear The two values ​​are compared, and the larger value is taken as the first separation rate. The reason for this setting is that if the clutch disengages too slowly in neutral, it can cause the clutch to continuously slip and rub unnecessarily, which is detrimental to the life of the friction plates and thermal management. Therefore, a lower limit for the disengagement rate in neutral is required. For neutral state recognition itself, existing technologies such as gear position displacement recognition, gear position sensor recognition, or internal controller state quantity recognition can be used. At this point, the calculation path for the first disengagement rate is complete, and the system obtains the first disengagement rate. The separation rate This reflects the combined constraints of the vehicle's external environment, the current load state of the clutch, and the safety protection boundary on the clutch disengagement action.

[0066] Parallel to the first separation rate path is the second separation rate calculation path. This path primarily determines the clutch separation rate suitable for the current operating conditions based on the powertrain state, and therefore can be understood as a dynamic constraint path. First, it calculates the clutch separation rate based on the current engine torque. and clutch feedback torque The disengagement rate of the second basic clutch is determined based on a preset mapping relationship. The preset mapping relationship is preferably a two-dimensional lookup table, but it can also be implemented using existing multi-segment function mapping or the controller's internal calibration matrix. In this mapping relationship, the clutch feedback torque... The larger the value, the faster the second basic clutch disengages. The larger; the higher the current engine torque The smaller the value, the faster the second basic clutch disengages. The larger the torque, the better; when the clutch feedback torque is greater. When the torque value is less than the preset value, the disengagement rate of the second basic clutch is... Maintain a small value and no longer change with the current engine torque. The purpose of this setting is that when the clutch is still under a large torque and the engine's output torque is relatively small, the powertrain is more likely to experience a dragging or sluggish tendency, so the disengagement rate should be increased; while when the clutch feedback torque is already small and the powertrain coupling effect is not strong, the necessity to make large adjustments based on the current engine torque decreases, and maintaining a smaller disengagement rate is more conducive to a smooth transition.

[0067] After obtaining the second basic clutch disengagement rate Subsequently, this embodiment continues to perform dynamic feedback correction based on the difference between the current engine speed and the engine idle speed, as well as the engine speed change rate, to obtain the separation rate after dynamic feedback correction. Preferably, the difference between the current engine speed and the engine idle speed is defined as the speed difference. Assume the rate of change of engine speed is Furthermore, a first speed change rate threshold is preset. Second speed change rate threshold and the third speed difference threshold The second speed change rate threshold Greater than the first speed change threshold .

[0068] When the engine speed change rate Greater than the first speed change rate threshold At that time, no dynamic feedback correction is performed;

[0069] When the speed difference Greater than the third speed difference threshold And the rate of change of engine speed Greater than the second speed change rate threshold At the same time, no dynamic feedback correction is performed;

[0070] In all other cases, dynamic feedback correction is performed, and the dynamic feedback correction value is adjusted accordingly. With speed difference Decrease and increase, while also changing with the rate of change of engine speed. Decrease and increase. In other words, when the engine's current speed gets closer to idle, or when the engine deceleration increases, the system will actively increase the dynamic feedback correction value. This improves the corrected separation rate. Through this dynamic feedback correction process, the second separation rate path can reflect the real-time trend of whether the powertrain is becoming more dangerous, rather than just reflecting the static torque magnitude at a certain moment. Ultimately, the second separation rate... Take the separation rate after dynamic feedback correction .

[0071] First separation rate Second separation rate After all calculations are completed, this embodiment enters the low-speed operating condition judgment and output separation rate selection stage. Specifically, the theoretically calculated starting gear can be determined based on the slope and vehicle mass through a preset mapping relationship. The gear difference between the current gear and the theoretically calculated starting gear is defined as the gear number corresponding to the current gear minus the gear number corresponding to the theoretically calculated starting gear. When the gear difference is less than a preset gear offset threshold, or when the current gear is reverse, the vehicle is determined to be in a low-speed driving condition. Mature solutions already exist in the field for determining the theoretically calculated starting gear, estimating the vehicle mass, and mapping gear numbers, and can be implemented using existing technologies. As an optional embodiment, the preset gear offset threshold can be, for example, 2.

[0072] When the system determines that the vehicle is in a low-speed driving condition, the first separation rate is taken. With the second separation rate The smaller value in the range is used as the initial output separation rate. ;

[0073] If the system does not determine that the vehicle is in a low-speed driving condition, the first separation rate is directly taken. As the initial output separation rate .

[0074] The reason for using a smaller value under low-speed conditions is that the transmission ratio is larger in low gears, resulting in a significant torque amplification effect. Furthermore, the inertia of the vehicle and transmission system is lower at low speeds, making them more sensitive to shocks from powertrain engagement and disengagement. Therefore, it is necessary to consider the limitations of both the environmental path and the power path, selecting the more conservative result to reduce the risk of jerking. Under non-low-speed sensitive conditions, the environmental path provides the first separation rate. Usually, the control requirements can be met, and the first separation rate can be used directly.

[0075] After obtaining the initial output separation rate Furthermore, this embodiment further performs separate re-control at the end of the clutch disengagement stroke to obtain the final disengagement rate. Specifically, it is preferable to set the braking signal as a braking signal. Among them, the braking signal A value of 0 indicates that the vehicle currently has no handbrake or foot brake, and therefore no braking signal. A value of 1 indicates that the vehicle currently has either the handbrake or foot brake engaged; let the theoretically calculated starting gear be the theoretical starting gear. Let the difference between the current engine speed and the engine idle speed be the speed difference. Let the target torque of the clutch be the target torque of the clutch. Let the preset first clutch target torque threshold be the clutch target torque threshold. .

[0076] Furthermore, a braking signal is triggered when the following four conditions are met, i.e., condition one. The condition is that the current gear is equal to the theoretical starting gear, which is 0. Condition 3 is the speed difference. The torque is greater than the fourth speed difference threshold, and the fourth condition is the clutch target torque. Less than the clutch target torque threshold The system is based on the rate of change of engine speed. The final separation rate is determined based on a preset mapping relationship. The preset mapping relationship is preferably a one-dimensional lookup table, but it can also be implemented using a calibration function in the prior art, while satisfying the engine speed change rate. The smaller the value, the higher the final separation rate. The larger the trend, the more it needs to meet the final separation rate requirements. The maximum value is less than the initial output separation rate. If the above four conditions cannot be met simultaneously, the final separation rate will be... Take the initial output separation rate directly The significance of this setup is that, during the phase where the clutch is nearly fully open, the system no longer simply uses the rate results from the initial and middle stages, but instead performs a separate end-stage shaping. This ensures that the final decoupling action is as smooth as possible, while preventing the end-stage separation from being too slow and affecting control stability. The specific values ​​for the one-dimensional lookup table, the filtering algorithm, and the actuator drive parameters can be implemented using existing calibration methods.

[0077] like Figure 2 As shown, in a low-speed, non-shifting control scenario, after the throttle opening decreases, the clutch target torque gradually decreases according to the control target. Simultaneously, the changes in engine speed, transmission input shaft speed, and vehicle speed are relatively continuous, without significant drastic fluctuations. This indicates that, under the method of this embodiment, the change trend of the clutch target torque can be well coordinated with the changes in engine speed, transmission input shaft speed, and vehicle speed, thus maintaining good continuity in the power interruption process. It also demonstrates that the dual-path parallel calculation, low-speed condition optimal selection, and end-point individual shaping in this embodiment are not isolated logical steps, but rather a control chain that can collectively act on the actual operation of the vehicle.

[0078] Scene 1:

[0079] This embodiment can be used for low-speed coasting in urban congestion. At this time, the driver releases the accelerator pedal, the vehicle does not request a gear shift, and the vehicle is in a low gear. The system first acquires all input signals according to step S1, and then, based on the slope value... and turning radius Obtain the basic clutch disengagement rate And combined with the initial clutch feedback torque The corrected separation rate was obtained. ;

[0080] If the engine speed change rate Speed ​​difference and the current engine torque If the first-level protection conditions are met, the separation rate will be further increased to a level no lower than the first-level protection separation rate. If the speed difference If the separation rate is further reduced to meet the secondary protection conditions, then the separation rate is increased to a level not lower than the second protection separation rate. .

[0081] At the same time, the system also adjusts the engine's current torque. and clutch feedback torque Calculate the disengagement rate of the second basic clutch And based on the speed difference and engine speed change rate Dynamic feedback correction is performed to obtain the second separation rate. .

[0082] If the difference between the current gear and the theoretically calculated starting gear is less than the preset gear offset threshold, the system determines that the vehicle is in a low-speed driving condition and takes the first separation rate. With the second separation rate The smaller value in the range is used as the initial output separation rate. When the clutch target torque When the speed continues to decrease and the end-of-line control condition is met, the system will then adjust the engine speed according to the rate of change. Obtain the final separation rate Through this continuous control process, the transition of the clutch from engagement to disengagement will not exhibit the abrupt changes common under single fixed-rate control.

[0083] In low-speed coasting scenarios, this embodiment restricts clutch disengagement through both environmental and power paths, and further reshapes the execution speed at the end, thereby helping to reduce powertrain impact and vehicle speed fluctuations.

[0084] Scene 2:

[0085] This embodiment can be used in low-speed uphill or low-speed turning scenarios. Compared to the aforementioned low-speed coasting process, changes in the vehicle's external environment are more sensitive to clutch disengagement in this situation. For example, on steep inclines, the vehicle requires higher driving force; on narrow turning radii, the vehicle is more sensitive to attitude changes caused by sudden torque fluctuations. In this case, the system first determines the clutch disengagement action based on the incline value. and turning radius The basic clutch disengagement rate is obtained by referring to the table. Combined with the initial clutch feedback torque Determine the corrected separation rate .

[0086] If the initial clutch feedback torque If it is higher, then the correction value is higher. A positive value indicates that the system tends to increase the separation rate;

[0087] If the initial clutch feedback torque If it is lower, then the correction value is lower. A negative value indicates that the system tends to reduce the separation rate in order to keep the process smooth.

[0088] Subsequently, if the engine speed change rate Speed ​​difference and the current engine torque Upon entering the protection zone simultaneously, the primary and secondary protection mechanisms will activate sequentially to ensure that the separation rate is at least not lower than the protection boundary. During this process, the second separation rate path will continue to adjust based on the current engine torque. Clutch feedback torque Speed ​​difference and engine speed change rate For the second separation rate Calculations are performed to create real-time supplementary constraints for the environmental path output.

[0089] In scenarios involving low-speed uphill driving or low-speed turning, this embodiment does not simply increase the clutch disengagement rate. Instead, it adjusts the clutch disengagement action in a hierarchical manner under the combined effect of the environmental path and the power path, in order to balance the protection boundary and dynamic smoothness.

[0090] Scene 3:

[0091] This embodiment can be used in low-speed deceleration scenarios where engine speed drops rapidly and there is a significant risk of stalling. In this scenario, the engine's current speed gradually approaches its idle speed, and the speed difference... Significantly reduced, engine speed change rate This is also within a relatively small range, indicating a significant engine deceleration. At this point, on the one hand, the primary and secondary protection mechanisms in the first separation rate path can ensure that the separation rate is not lower than the first protection separation rate. Second protection separation rate On the other hand, the dynamic feedback correction in the second separation rate path also changes with the speed difference. Reduce and engine speed change rate Decrease and increase the dynamic feedback correction value This increases the second separation rate. .

[0092] Therefore, this embodiment does not rely on a single-point judgment for control in scenarios where the risk of engine stalling increases. Instead, it forms a dual constraint through graded protection in the environmental path and dynamic correction in the power path. After the engine stalling risk has been suppressed in the current and middle stages, if the vehicle further enters the stage where the clutch is almost fully open, the system will meet the following conditions: no braking, the current gear equals the theoretically calculated starting gear, and the speed difference... Greater than the fourth speed difference threshold and the clutch target torque Less than the clutch target torque threshold Under these conditions, and based on the engine speed change rate Re-determine the final separation rate This is to keep the decoupling action at the end smooth.

[0093] In low-speed deceleration scenarios where the risk of engine stalling is high, this embodiment can both increase the separation rate in time through the initial and middle stages of control, and reduce the abruptness of the final decoupling through the final stage of control.

[0094] Scene 4:

[0095] This embodiment can be used in neutral gear management mode or near neutral gear shift mode. In this scenario, after the system identifies the current gear as neutral, it will adjust the separation rate after secondary protection. Disengagement rate with neutral gear The two values ​​are compared, and the larger value is taken as the first separation rate. Because maintaining a low clutch disengagement rate for an extended period in neutral can easily lead to unnecessary slippage, it is necessary to control the clutch disengagement rate in neutral. An additional lower bound constraint is imposed on the first separation rate path.

[0096] For the identification of neutral state, the motion control of actuators, and related safety interlocking relationships, there are mature solutions in this field that can be implemented using existing technologies.

[0097] In special operating conditions such as neutral or near neutral, this embodiment sets the neutral disengagement rate. This avoids the clutch being in an adverse state for a long time under special operating conditions, so that the control logic of this application is applicable not only to normal low-speed driving conditions, but also to separation control under special conditions.

[0098] As can be seen from the aforementioned implementation scenarios, the control focus of this embodiment is not on setting a fixed disengagement speed for the clutch, but rather on establishing a complete control chain from input signal acquisition to final disengagement rate output throughout the entire clutch disengagement process. In this chain, the first disengagement rate path primarily handles external environmental constraints and hierarchical protection boundary control; the second disengagement rate path primarily handles real-time powertrain state constraints; the low-speed operating condition judgment module primarily handles target operating condition identification and output optimization; and the end-of-line re-control module primarily handles the refinement of the final decoupling process.

[0099] In addition, the specific calibration values ​​of the lookup table, the specific settings of the threshold parameters, the specific selection of the filter time constant, the speed conversion method of the actuator, and the control cycle settings can be conventionally selected and optimized by those skilled in the art using existing technologies according to different vehicle models and control platforms, as long as they do not deviate from the control logic defined in this application.

Claims

1. A method for optimizing the smoothness control of AMT clutch disengagement rate, characterized in that, Includes the following steps: S1. Obtain the input signals required for clutch disengagement rate control. The input signals include at least the current engine speed, engine idle speed, current engine torque, clutch feedback torque, engine speed change rate, slope, turning radius, current gear, theoretically calculated starting gear, braking signal, and clutch target torque. S2. Determine the basic clutch disengagement rate based on the slope and turning radius, and correct the basic clutch disengagement rate based on the initial clutch feedback torque. Then, combine the anti-drag protection, anti-stalling protection and neutral mode control in sequence to obtain the first disengagement rate. S3. Determine the second basic clutch disengagement rate based on the current engine torque and the clutch feedback torque, and perform dynamic feedback correction based on the speed difference between the current engine speed and the engine idle speed and the engine speed change rate to obtain the second disengagement rate; S4. Determine whether the vehicle is in a low-speed driving condition based on the relationship between the current gear and the theoretically calculated starting gear. When in a low-speed driving condition, take the smaller value between the first separation rate and the second separation rate as the initial output separation rate. When not in a low-speed driving condition, take the first separation rate as the initial output separation rate. S5. When the preset end control conditions are met, determine the final separation rate at the end of the clutch separation stroke based on the engine speed change rate; If the preset end control conditions are not met, the initial output separation rate is taken as the final separation rate.

2. The method for optimizing the smoothness control of the AMT clutch disengagement rate as described in claim 1, characterized in that, In step S1: The input signals include CAN bus signals, external sensor signals, and TCU internal signals; The CAN bus signals include the current engine speed, engine idle speed, relative wheel speed, and foot brake and handbrake signals. The external sensor signals include clutch feedback torque, ramp and gear displacement; The internal signals of the TCU include the clutch target torque, engine speed change rate, turning radius, current gear, and theoretically calculated starting gear.

3. The method for optimizing the smoothness control of the AMT clutch disengagement rate as described in claim 1, characterized in that, In step S2, the basic clutch disengagement rate is corrected based on the initial clutch feedback torque, specifically as follows: Compare the initial clutch feedback torque with a preset torque threshold; When the initial clutch feedback torque is greater than the preset torque threshold, a positive correction value is used to correct the basic clutch disengagement rate, and the absolute value of the positive correction value increases as the initial clutch feedback torque increases. When the initial clutch feedback torque is less than the preset torque threshold, a negative correction value is used to correct the basic clutch disengagement rate, and the absolute value of the negative correction value increases as the initial clutch feedback torque decreases.

4. The method for optimizing the smoothness control of the AMT clutch disengagement rate as described in claim 1, characterized in that, The anti-reverse drag protection in step S2 includes: When the engine speed change rate is less than the first speed change rate threshold, the speed difference between the current engine speed and the engine idle speed is less than the first speed difference threshold, and the current engine torque is less than the first torque threshold, the anti-reverse drag protection is triggered. After the anti-reverse drag protection is triggered, the corrected separation rate is compared with the first protection separation rate, and the larger of the two values ​​is taken as the separation rate after the anti-reverse drag protection.

5. The method for optimizing the smoothness control of the AMT clutch disengagement rate as described in claim 4, characterized in that, Step S2 includes flameout protection and neutral mode control, which include: When the speed difference between the current engine speed and the engine idle speed is less than the second speed difference threshold, the anti-stalling protection is triggered, and the separation rate after the anti-reverse drag protection is compared with the second protection separation rate. The larger of the two values ​​is taken as the separation rate after the anti-stalling protection, wherein the second protection separation rate is greater than the first protection separation rate. When the current gear is neutral, the separation rate after the anti-stalling protection is compared with the neutral separation rate, and the larger of the two values ​​is taken as the first separation rate.

6. The method for optimizing the smoothness control of the AMT clutch disengagement rate as described in claim 1, characterized in that, In step S3, when determining the second basic clutch disengagement rate based on the current engine torque and the clutch feedback torque, the following mapping relationship is satisfied: The greater the clutch feedback torque, the greater the disengagement rate of the second basic clutch. The lower the current torque of the engine, the greater the disengagement rate of the second basic clutch; When the clutch feedback torque is less than the preset torque value, the second basic clutch disengagement rate remains at a small value and no longer changes with the current engine torque.

7. The method for optimizing the smoothness control of the AMT clutch disengagement rate as described in claim 1, characterized in that, The dynamic feedback correction in step S3 includes: A first speed change rate threshold, a second speed change rate threshold, and a third speed difference threshold are preset, wherein the second speed change rate threshold is greater than the first speed change rate threshold; When the rate of change of engine speed is greater than the first rate of change of engine speed threshold, no dynamic feedback correction is performed; When the difference between the current engine speed and the engine idle speed is greater than the third speed difference threshold, and the rate of change of engine speed is greater than the second rate of change of engine speed threshold, no dynamic feedback correction is performed. In other cases, dynamic feedback correction is performed, and the dynamic feedback correction value increases as the speed difference decreases and as the rate of change of engine speed decreases.

8. The method for optimizing the smoothness control of the AMT clutch disengagement rate as described in claim 1, characterized in that, In step S4: The theoretically calculated starting gear is determined based on the slope and the vehicle's mass through a preset mapping relationship. The gear difference between the current gear and the theoretically calculated starting gear is the gear number corresponding to the current gear minus the gear number corresponding to the theoretically calculated starting gear. When the gear difference is less than the preset gear offset threshold, or when the current gear is reverse, the vehicle is determined to be in a low-speed driving condition.

9. The method for optimizing the smoothness control of the AMT clutch disengagement rate as described in claim 1, characterized in that, The preset end-point control conditions in step S5 include at least the following: Braking signals indicate that the vehicle has neither a handbrake nor a foot brake; The current gear is equal to the theoretically calculated starting gear; The difference between the current engine speed and the engine idle speed is greater than the fourth speed difference threshold. The clutch target torque is less than the preset first clutch target torque threshold.

10. The method for optimizing the smoothness control of the AMT clutch disengagement rate as described in claim 9, characterized in that, In step S5, when determining the final disengagement rate at the end of the clutch disengagement stroke based on the engine speed change rate, the following relationship is satisfied: The smaller the rate of change of engine speed, the greater the final separation rate; Furthermore, the maximum value of the final separation rate is less than the initial output separation rate.

Images