AMT clutch friction point self-learning intermediate shaft brake control method and device

Abstract

The embodiment of the invention discloses an AMT clutch friction point self-learning intermediate shaft brake control method and device. The control method comprises the steps that the oil temperature of a transmission and the target speed reduction rate of an intermediate shaft brake are obtained; according to the transmission oil temperature and the target speed reduction rate, based on the target inflation time array, the inflation duration of the intermediate shaft brake is determined; and according to the inflation duration, the intermediate shaft brake is inflated. According to the technical scheme provided by the embodiment of the invention, the problem of overlong braking time or excessive braking of the intermediate shaft brake can be solved by controlling the inflation duration of the intermediate shaft brake.

Description

Technical Field

[0001] This invention relates to the field of automatic transmission control technology, and in particular to a control method and device for an intermediate shaft brake with self-learning friction point of an AMT clutch. Background Technology

[0002] In an Automated Manual Transmission (AMT), the clutch's function is to regulate the connection between the engine's power output and the transmission, cut off transient power transmission between them, and achieve smooth vehicle start-up and coordinated gear shifting through overload protection and other functions, thereby minimizing gear impact and extending the service life of the transmission system. However, during use, the clutch's torque transmission capability changes due to increased wear of friction elements and thermal expansion of the friction plates. Therefore, performing clutch friction point self-learning at appropriate times can ensure its torque transmission accuracy.

[0003] The function of the intermediate shaft brake is to lock the intermediate shaft during gear shifting, enabling it to quickly reduce to the target speed for the next gear. Because the intermediate shaft brake is pneumatically controlled, it exhibits a significant time lag. During clutch self-learning, if the intermediate shaft deceleration time is too long, the intermediate shaft brake protection mechanism will be triggered. Existing AMTs (Automated Manual Transmission systems) suffer from problems with excessively long braking times or over-braking in their intermediate shaft brakes during operation. Summary of the Invention

[0004] This invention provides a control method and device for an intermediate shaft brake with self-learning friction point of an AMT clutch, in order to solve the problem of excessive braking time or over-braking caused by unreasonable inflation time setting of the intermediate shaft brake.

[0005] To address the aforementioned technical problems, the present invention adopts the following technical solution:

[0006] In a first aspect, embodiments of the present invention provide a control method for an intermediate shaft brake with self-learning friction point of an AMT clutch, comprising:

[0007] Obtain the transmission oil temperature and the target deceleration rate of the intermediate shaft brake;

[0008] Based on the transmission oil temperature and the target deceleration rate, and using the target inflation time array, the inflation duration of the intermediate shaft brake is determined.

[0009] The intermediate shaft brake is inflated according to the inflation duration.

[0010] Optionally, before obtaining the transmission oil temperature and the target deceleration rate of the intermediate shaft brake, the method further includes:

[0011] Under the clutch self-learning state, the intermediate shaft brake at the moment of braking start is obtained as follows: front auxiliary gearbox gear position, intermediate shaft speed, output shaft speed, front auxiliary gearbox speed ratio, and target gear ratio.

[0012] Based on the intermediate shaft speed and the gear position of the front auxiliary gearbox at the moment of braking start, determine the basic value of the target deceleration rate of the intermediate shaft brake;

[0013] The target deceleration rate compensation value of the intermediate shaft is determined based on the output shaft speed of the intermediate shaft brake, the speed ratio of the front auxiliary gearbox, and the target gear ratio.

[0014] The target deceleration rate of the intermediate shaft brake is determined based on the sum of the base value of the target deceleration rate of the intermediate shaft brake and the compensation value of the target deceleration rate of the intermediate shaft brake.

[0015] Optionally, determining the target deceleration rate compensation value of the intermediate shaft based on the output shaft speed of the intermediate shaft brake, the front auxiliary gearbox speed ratio, and the target gear ratio includes:

[0016] The input shaft speed is determined based on the ratio of the output shaft speed of the intermediate shaft brake to the target gear ratio;

[0017] The target deceleration rate compensation value of the intermediate shaft is determined based on the ratio of the input shaft speed to the front auxiliary gearbox speed ratio.

[0018] Optionally, determining the inflation duration of the intermediate shaft brake based on the transmission oil temperature and the target deceleration rate, using a target inflation time array, includes:

[0019] Based on the target inflation time array, the inflation time of the intermediate shaft brake is determined by looking up a table according to the transmission oil temperature and the target deceleration rate.

[0020] Optionally, inflating the intermediate shaft brake according to the inflation duration includes:

[0021] Close the exhaust valve of the intermediate shaft brake;

[0022] Open the air intake valve of the intermediate shaft brake and keep the air intake valve in the open state according to the inflation duration to inflate the intermediate shaft brake.

[0023] Optionally, before determining the inflation duration of the intermediate shaft brake based on the transmission oil temperature and the target deceleration rate, and using a target inflation time array, the method further includes:

[0024] The vehicle engine is kept at idle speed, the transmission is in neutral, and the vehicle air pressure reaches the set value.

[0025] Obtain the vehicle self-learning request. When the vehicle self-learning request is for parking clutch self-learning, obtain the input shaft speed value.

[0026] When the input shaft speed is greater than the preset input shaft speed for the clutch friction point self-learning start, the target inflation time array of the intermediate shaft brake is determined according to the input shaft speed and the clutch friction point self-learning process.

[0027] Control the clutch to disengage to the fully disengaged position and activate the intermediate shaft brake to reduce the speed of the intermediate shaft.

[0028] Optionally, after inflating the intermediate shaft brake according to the inflation duration, the method further includes:

[0029] Obtain the current rotational speed of the intermediate shaft brake;

[0030] The inflation state of the intermediate shaft brake is controlled based on the difference between the current rotational speed and the target deceleration rate.

[0031] Optionally, after controlling the inflation state of the intermediate shaft brake based on the difference between the current rotational speed and the target deceleration rate, the method further includes:

[0032] Control the clutch to engage at a preset speed;

[0033] Obtain the input shaft deceleration rate, the equivalent moment of inertia of the input shaft, and the input shaft acceleration rate of the transmission.

[0034] The torque value transmitted during the clutch engagement process is determined by summing the product of the input shaft deceleration rate and the equivalent moment of inertia of the input shaft with the product of the equivalent moment of inertia of the input shaft and the acceleration rate of the transmission input shaft.

[0035] The clutch position is determined based on the difference between the torque value transmitted by the clutch and the set torque value transmitted by the clutch at the friction point.

[0036] Optionally, determining the clutch position based on the difference between the clutch's transmitted torque value and the clutch's transmitted torque set value at the friction point includes:

[0037] When the clutch transmission torque is greater than or equal to the set value of the clutch transmission torque at the friction point, record the current clutch position and increment the friction point self-learning count by 1.

[0038] Control the clutch to engage at a preset speed until it is fully engaged;

[0039] When the number of self-learning times of the clutch friction point exceeds the set value, the arithmetic mean of the multiple recorded clutch positions is taken as the clutch friction point.

[0040] Secondly, embodiments of the present invention provide a control device for an intermediate shaft brake with self-learning friction point of an AMT clutch, comprising:

[0041] The acquisition module is used to acquire the transmission oil temperature and the target deceleration rate of the intermediate shaft brake.

[0042] The determination module is used to determine the inflation duration of the intermediate shaft brake based on the transmission oil temperature and the target deceleration rate, and on a target inflation time array.

[0043] An inflation module is used to inflate the intermediate shaft brake according to the inflation duration.

[0044] This invention pre-defines a target inflation time array suitable for the self-learning scenario of the AMT clutch friction point. Then, using a pre-stored MAP1 table corresponding to the transmission oil temperature, brake system air pressure, and inflation time arrays, the required target inflation time array for this scenario is selected. Finally, by detecting the transmission oil temperature and the target deceleration rate, the inflation duration adapted to the current operating condition is matched, achieving refined control of the intermediate shaft brake. This method solves the problems of excessive braking time or over-braking caused by the time lag in pneumatic control of the intermediate shaft brake and unreasonable pneumatic dual-valve control. It avoids situations where the brake protection mechanism is triggered due to slow deceleration of the intermediate shaft during clutch self-learning, or where over-braking affects the self-learning accuracy. This invention achieves the beneficial effect of ensuring that the intermediate shaft quickly and smoothly decelerates to the target speed, improving the accuracy and efficiency of clutch friction point self-learning, while reducing shift delays caused by improper brake control. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of the present invention and these drawings without creative effort.

[0046] Figure 1 This is a flowchart of a control method for an intermediate shaft brake with self-learning friction point of an AMT clutch provided in an embodiment of the present invention;

[0047] Figure 2 This is a flowchart of another control method for an intermediate shaft brake with self-learning friction point of an AMT clutch provided in an embodiment of the present invention;

[0048] Figure 3This invention provides a control device for an intermediate shaft brake with self-learning friction point of an AMT clutch. Detailed Implementation

[0049] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0050] Figure 1 This is a flowchart illustrating a control method for an intermediate shaft brake in an AMT clutch friction point self-learning process, provided by an embodiment of the present invention. This embodiment is applicable to situations where the intermediate shaft brake is controlled during the AMT clutch friction point self-learning process. This method can be executed by a control device for the intermediate shaft brake in an AMT clutch friction point self-learning process. This control device can be implemented in hardware and / or software and can be configured in the transmission control unit (TCU). Figure 1 As shown, the method includes the following steps:

[0051] S110: Obtain the transmission oil temperature and the target deceleration rate of the intermediate shaft brake.

[0052] Specifically, transmission oil temperature affects the braking force of the intermediate shaft brake. When the oil temperature is too low, the elasticity of the seals inside the brake cylinder decreases, the air resistance increases, and the compressed air filling speed slows down, resulting in a weaker braking force from the intermediate shaft brake. When the oil temperature is too high, the seals inside the brake cylinder expand, improving the air circuit sealing and causing the filling pressure to rise faster, resulting in a stronger braking force from the intermediate shaft brake. The target deceleration rate is the rate at which the intermediate shaft speed decreases to meet the requirements of the clutch friction point self-learning mechanism during intermediate shaft brake operation.

[0053] S120. Based on the transmission oil temperature and the target deceleration rate, determine the inflation duration of the intermediate shaft brake according to the target inflation time array.

[0054] Specifically, the TCU pre-stores two inflation time arrays: a first array for normal driving and a second array for self-learning when the vehicle is stationary. When the TCU determines that the vehicle is stationary and initiates the self-learning program, it selects the second array as the target inflation time array based on the pre-stored MAP1 table corresponding to the transmission fluid temperature, brake system air pressure, and inflation time arrays. The MAP1 table is a two-dimensional parameter lookup table pre-stored in the TCU. The horizontal parameter of the MAP1 table is the transmission fluid temperature, and the vertical parameter is the brake system air pressure. The data in the table corresponds to the inflation time array for each combination of fluid temperature and air pressure. Then, the TCU matches the most suitable inflation time from the target inflation time array based on the detected transmission fluid temperature and the target deceleration rate. At the same fluid temperature, a higher target deceleration rate requires a longer inflation time; conversely, at the same target deceleration rate, a lower fluid temperature requires a longer inflation time.

[0055] S130. Inflate the intermediate shaft brake according to the inflation time.

[0056] Specifically, insufficient inflation time leads to inadequate braking force, resulting in a slow deceleration process for the intermediate shaft, or even preventing it from coming to a complete stop. Conversely, excessive inflation time generates excessive braking force, leading to over-braking. By determining the inflation time through the above steps, the inflation operation on the intermediate shaft brake can be precisely matched to the actual braking time requirement of the intermediate shaft brake, thereby avoiding excessively long or short braking times and achieving precise control over the braking time of the intermediate shaft brake.

[0057] This invention pre-defines a target inflation time array suitable for the self-learning scenario of the AMT clutch friction point. Then, using a pre-stored MAP1 table corresponding to the transmission oil temperature, brake system air pressure, and inflation time arrays, the required target inflation time array for this scenario is selected. Finally, by detecting the transmission oil temperature and the target deceleration rate, the inflation duration adapted to the current operating condition is matched, achieving refined control of the intermediate shaft brake. This method solves the problems of excessive braking time or over-braking caused by the time lag in pneumatic control of the intermediate shaft brake and unreasonable pneumatic dual-valve control. It avoids situations where the brake protection mechanism is triggered due to slow deceleration of the intermediate shaft during clutch self-learning, or where over-braking affects the self-learning accuracy. This invention achieves the beneficial effect of ensuring that the intermediate shaft quickly and smoothly decelerates to the target speed, improving the accuracy and efficiency of clutch friction point self-learning, while reducing shift delays caused by improper brake control.

[0058] Optionally, based on the above embodiments, before S110, the following may also be included:

[0059] Step 1: Under the clutch self-learning state, obtain the front auxiliary gearbox gear position, intermediate shaft speed, output shaft speed, front auxiliary gearbox speed ratio, and target gear ratio of the intermediate shaft brake at the moment of braking start.

[0060] Specifically, the front auxiliary gearbox position refers to the gear in which the auxiliary gearbox is located; the intermediate shaft speed is the real-time speed of the intermediate shaft at the start of braking; the output shaft speed is the speed of the shaft connecting the wheels, reflecting the actual vehicle speed; the front auxiliary gearbox ratio is the transmission ratio of the current gear in the front auxiliary gearbox; and the target gear ratio is the transmission ratio of the target gear during the self-learning process. These parameters are obtained in the clutch self-learning state. Clutch self-learning is a preset, controllable operating condition. Obtaining parameters in this state ensures that they are collected under ideal conditions, possessing consistency and comparability. Obtaining these parameters while the vehicle is in motion would cause the parameters to fluctuate dynamically, making it impossible to form a stable calculation basis.

[0061] Step 2: Determine the base value of the target deceleration rate of the intermediate shaft brake based on the intermediate shaft speed and the gear position of the front auxiliary gearbox at the moment of braking.

[0062] Specifically, the target deceleration rate base value depends on the current speed of the intermediate shaft and the gear position of the front and auxiliary gearboxes. A higher intermediate shaft speed results in greater initial kinetic energy, requiring stronger braking force, i.e., a higher target deceleration rate base value for a quick stop; a lower intermediate shaft speed results in less initial kinetic energy, requiring less braking force, i.e., a lower target deceleration rate base value. Different gear positions result in different transmission system inertia, thus requiring different base deceleration rates. The TCU has a preset MAP2 table. Based on the intermediate shaft speed and the gear position of the front and auxiliary gearboxes at the start of braking, the base deceleration rate value is obtained by looking up the table. The MAP2 table is a two-dimensional parameter lookup table. The horizontal parameter of the MAP2 table is the intermediate shaft speed at the start of braking, the vertical parameter is the gear position of the front and auxiliary gearboxes at the start of braking, and the data in the table is the base deceleration rate value under the current operating conditions. Using the pre-stored MAP2 table in the TCU, the system can match the optimal target deceleration rate base value according to the current operating conditions of the intermediate shaft speed and the gear position of the front and auxiliary gearboxes at the start of braking. This process allows the braking force of the intermediate shaft brake to be output according to the actual operating conditions.

[0063] Step 3: Determine the target deceleration rate compensation value of the intermediate shaft based on the output shaft speed of the intermediate shaft brake, the speed ratio of the front auxiliary gearbox, and the target gear ratio.

[0064] Specifically, the target deceleration rate compensation value is to compensate for the effects of minor vehicle vibrations. The ideal self-learning state is when the vehicle is completely stationary, i.e., the output shaft speed is 0. However, if the vehicle is stopped on a slope or experiences slight movement, additional inertia will be generated, affecting braking performance. Determining the intermediate shaft target deceleration rate compensation value ensures that the final deceleration after each self-learning process accurately matches the current actual operating conditions. Regardless of fluctuations in the output shaft speed or deviations in the front and auxiliary gear ratios, the target deceleration rate compensation value will dynamically adjust with these parameters, ensuring that the final speed after each intermediate shaft deceleration matches the actual value expected under the current operating conditions. This avoids a decrease in self-learning accuracy due to fluctuations in operating conditions.

[0065] Step 4: Determine the target deceleration rate of the intermediate shaft brake based on the sum of the base value of the target deceleration rate of the intermediate shaft brake and the target deceleration compensation value of the intermediate shaft brake.

[0066] Specifically, the target deceleration rate is obtained by adding the base value of the target deceleration rate to the compensation value of the target deceleration rate. For example, if the base value of the target deceleration rate is 150 rpm / s and the compensation value of the target deceleration rate is 20 rpm / s, the final target deceleration rate is 170 rpm / s, which means that the intermediate shaft needs to reduce its speed by 170 rpm per second to reach the target speed within the expected time.

[0067] This invention provides a two-step calculation process: a base value for the target deceleration rate to ensure basic requirements and a compensation value for the target deceleration rate to adapt to actual differences. The resulting target deceleration rate satisfies the clutch self-learning requirements for deceleration speed and adapts to specific operating conditions such as the current gear and speed. This avoids problems of deceleration being too fast or too slow, provides a reliable basis for precise control of inflation time, and improves the stability and accuracy of the self-learning process.

[0068] Optionally, based on the above embodiments, step three, determining the intermediate shaft target deceleration rate compensation value according to the output shaft speed of the intermediate shaft brake, the front auxiliary gearbox speed ratio, and the target gear ratio, may include:

[0069] First, the input shaft speed is determined based on the ratio of the output shaft speed of the intermediate shaft brake to the target gear speed ratio.

[0070] Specifically, the input shaft connects the engine and the clutch. The input shaft speed needs to be correlated with the intermediate shaft speed through the target gear ratio to achieve power transmission. However, the input shaft speed cannot be directly measured and must be derived from the output shaft speed and the target gear ratio.

[0071] Secondly, the target deceleration rate compensation value of the intermediate shaft is determined based on the ratio of the input shaft speed to the front auxiliary gearbox speed.

[0072] Specifically, the intermediate shaft speed and the input shaft speed are correlated through the front auxiliary gearbox speed. The calculation of the target deceleration rate compensation value essentially quantifies the additional workload on the intermediate shaft brake caused by vehicle vibration. When the vehicle tends to vibrate forward, the target deceleration rate compensation value is positive, meaning the brake needs to provide stronger braking force, i.e., a higher target deceleration rate, to offset the interference of forward vibration on the intermediate shaft speed. When the vehicle tends to vibrate backward, the compensation value is negative, indicating that it is not necessary to maintain the original braking force intensity; the braking force of the brake can be appropriately reduced, which can still ensure that the intermediate shaft speed stably drops to the target value. For example, if the output shaft speed is 50 rpm and the target gear ratio is 2.0 (i.e., the input shaft rotates 1 revolution for the output shaft to rotate 2 revolutions), then the input shaft speed in the target gear = 50 rpm / 2.0 = 25 rpm, meaning that when the input shaft rotates 25 rpm, the output shaft rotates 50 rpm. If the speed ratio of the front and auxiliary gearboxes is 1.2, that is, the input shaft rotates 1.2 times for every 1 revolution of the intermediate shaft, then the target deceleration rate compensation value = 25rpm / 1.2≈20.8rpm.

[0073] This compensation mechanism design can effectively adapt to different parking scenarios. Whether the vehicle is parked on flat ground or on a slope, the target deceleration rate compensation value can be dynamically adjusted to correct the interference of vehicle vibration on the braking process, ensuring that the intermediate axle can always brake smoothly according to the expected target deceleration rate.

[0074] Optionally, based on any of the above embodiments, S120 includes:

[0075] Based on the target inflation time array, the inflation time of the intermediate shaft brake is determined by looking up a table according to the transmission oil temperature and the target deceleration rate.

[0076] The target inflation time array is essentially a two-dimensional lookup table. The rows and columns of the table correspond to the transmission oil temperature and the target deceleration rate, respectively, while each cell in the table represents the optimal inflation time determined in advance through experiments. The advantage of determining the inflation time by looking up the table is that it eliminates the need for real-time calculations of complex formulas; it directly matches the parameters to the values, thus meeting the real-time requirements of vehicle control.

[0077] Optionally, based on any of the above embodiments, S130 includes:

[0078] Close the exhaust valve of the intermediate shaft brake.

[0079] Open the air inlet valve of the intermediate shaft brake and keep the air inlet valve open for the duration of inflation to inflate the intermediate shaft brake.

[0080] The exhaust valve's function is to release compressed air from the brake chamber into the atmosphere when braking is needed, allowing the brake to return to its original position under spring pressure and release the brake. Before inflation begins, the exhaust valve must be completely closed. If the exhaust valve is open, compressed air will enter the brake cylinder through the intake port and then leak out through the exhaust port, failing to build pressure in the brake chamber, resulting in inflation failure and the brake failing to generate braking force. The intake valve is the valve that allows compressed air to enter the brake chamber. After opening the intake valve, compressed air flows into the brake cylinder through the air passage, the cylinder pressure begins to rise, and the brake begins to generate braking force. The TCU then controls the opening time of the intake valve according to the previously calculated inflation duration. If the inflation duration is too short, the inflation volume is insufficient, the brake cylinder pressure is insufficient, the braking force is weak, and the intermediate shaft decelerates slowly; if the inflation duration is too long, the inflation volume is excessive, the brake cylinder pressure is too high, the braking force is too large, and over-braking is likely. In this embodiment of the invention, the exhaust valve is closed first, which solves the problem of air leakage during inflation and ensures that the air pressure can be effectively established; then the intake valve is opened according to the inflation time, which solves the problem of inaccurate inflation volume and ensures that the braking force is just matched with the target deceleration requirement.

[0081] Optionally, based on any of the above embodiments, before S120, the method further includes:

[0082] The vehicle engine is kept at idle speed, the transmission is in neutral, and the vehicle air pressure reaches the set value.

[0083] Obtain the vehicle self-learning request. When the vehicle self-learning request is for parking clutch self-learning, obtain the input shaft speed value.

[0084] When the input shaft speed is greater than the preset input shaft speed value for clutch friction point self-learning startup, the target inflation time array of the intermediate shaft brake is determined based on the input shaft speed and the clutch friction point self-learning process.

[0085] Control the clutch to disengage to the fully disengaged position and activate the intermediate shaft brake to reduce the speed of the intermediate shaft.

[0086] Specifically, keeping the vehicle engine at idle speed ensures it maintains a minimum stable speed, preventing speed fluctuations from affecting power transmission stability. The transmission is in neutral to disconnect the engine from the drive wheels, ensuring the intermediate shaft deceleration is unaffected by driving resistance. Maintaining the vehicle's air pressure at a set value ensures the braking system has sufficient air pressure to drive the intermediate shaft brakes. Insufficient air pressure will prevent the brakes from generating sufficient braking force, causing the self-learning process to fail.

[0087] Vehicles have multiple self-learning modes, such as gear shift self-learning and clutch self-learning. Obtaining a vehicle-wide self-learning request is to confirm that the current mode is parking clutch self-learning, i.e., learning the clutch friction point while the vehicle is stationary. Once the self-learning type is determined, the TCU begins acquiring the input shaft speed value. The preset input shaft speed value is a pre-set speed threshold by the TCU to determine whether the input shaft state meets the self-learning activation conditions.

[0088] When the input shaft speed exceeds the preset value, it indicates that the clutch is engaged. Only in this state will the system initiate the clutch friction point self-learning program. At this time, the TCU selects the corresponding target inflation time array from the pre-stored array based on the current input shaft speed and the self-learning progress. Controlling the clutch to fully disengage is to cut off the power transmission between the engine and the transmission, preventing engine power from interfering with the intermediate shaft deceleration and ensuring that the intermediate shaft speed change is controlled only by the brake. Activating the intermediate shaft brake initiates the braking process. Only then will the TCU determine the inflation duration and control the intake valve to start inflation braking based on the preset inflation time array, transmission oil temperature, target deceleration rate, etc. It should be noted that the intermediate shaft deceleration time is the deceleration process of the intermediate shaft when there is no power transmission from the engine to the transmission input shaft and the transmission is in neutral. The above embodiment ensures that the self-learning process is initiated under the correct scenario.

[0089] Optionally, based on any of the above embodiments, after S130, the method further includes:

[0090] Get the current rotational speed of the intermediate shaft brake.

[0091] The inflation status of the intermediate shaft brake is controlled based on the difference between the current rotational speed and the target deceleration rate.

[0092] The acquisition of the current rotational speed of the intermediate shaft brake is crucial for obtaining real-time feedback signals. Without these signals, the system cannot determine the status of the braking command execution. Controlling the inflation state of the intermediate shaft brake based on the difference between the current rotational speed and the target deceleration rate involves the TCU comparing the real-time acquired current rotational speed with the expected rotational speed corresponding to the target deceleration rate, calculating the deviation, and adjusting the inflation state accordingly. If the current rotational speed of the intermediate shaft brake drops to the target deceleration rate, the intermediate shaft brake intake valve is closed, while the intermediate shaft brake exhaust valve is opened. If the current rotational speed of the intermediate shaft brake does not reach the target deceleration rate, the intake valve opening time is extended to increase braking force and accelerate deceleration. If the current rotational speed of the intermediate shaft brake decreases as expected, the current inflation state is maintained until the target rotational speed is reached. This embodiment of the invention, through a mechanism of real-time monitoring and differential adjustment, enables the system to flexibly adjust the inflation state according to the actual deceleration effect, ensuring that the intermediate shaft can quickly reach the target rotational speed without experiencing a sudden drop in rotational speed or component wear due to over-braking.

[0093] Optionally, after controlling the inflation state of the intermediate shaft brake based on the difference between the current rotational speed and the target deceleration rate, the method further includes:

[0094] Control the clutch to engage at a preset speed.

[0095] Obtain the input shaft deceleration rate, the equivalent moment of inertia of the input shaft, and the input shaft acceleration rate of the transmission.

[0096] The torque value transmitted during clutch engagement is determined by summing the product of the input shaft deceleration rate and the equivalent moment of inertia of the input shaft with the product of the equivalent moment of inertia of the input shaft and the acceleration rate of the transmission input shaft.

[0097] The clutch position is determined based on the difference between the clutch's transmitted torque value and the clutch's transmitted torque setting value at the friction point.

[0098] The preset speed refers to the mechanical movement speed of the clutch during engagement, pre-set by the TCU. It is a calibrated fixed value used to regulate the clutch's movement rhythm from complete disengagement to gradual engagement. Controlling the clutch to engage at the preset speed ensures consistent clutch engagement rhythm during each self-learning process, eliminates the interference of speed fluctuations on torque transmission characteristics, and makes the input shaft speed increase / decrease process smoother. The input shaft deceleration rate refers to the rate at which the input shaft speed decreases due to braking by the intermediate shaft during the initial clutch engagement. The equivalent moment of inertia of the input shaft is a pre-calibrated value stored within the TCU, representing the total moment of inertia of the entire rotating component on the braked side, translated to the input shaft. The transmission input shaft acceleration rate refers to the acceleration generated during clutch engagement as the clutch transmits torque, attempting to rotate the input shaft.

[0099] The formula for calculating the transmitted torque value is: Transmitted Torque Value = 2π * (Input Shaft Deceleration Rate * Input Shaft Equivalent Moment of Inertia + Transmission Input Shaft Acceleration Rate * Input Shaft Equivalent Moment of Inertia). The transmitted torque setting value refers to the preset torque value of the clutch at the friction point within the TCU. This is a calibrated target torque value, representing the magnitude of the torque that the clutch should transmit at the friction point. The TCU continuously compares the calculated transmitted torque value with this setting value to determine the clutch position.

[0100] Optionally, the clutch position is determined based on the difference between the clutch's transmitted torque value and the clutch's transmitted torque set value at the friction point, including:

[0101] When the torque transmitted by the clutch is greater than or equal to the set value of the torque transmitted by the clutch at the friction point, the current clutch position is recorded, and the self-learning count of the friction point is incremented by 1.

[0102] Control the clutch to engage at a preset speed until it is fully engaged.

[0103] When the number of self-learning times of the clutch friction point exceeds the set value, the arithmetic mean of the multiple recorded clutch positions is taken as the clutch friction point.

[0104] In this process, when the clutch transmission torque is greater than or equal to the set value of the clutch transmission torque at the friction point, the current clutch position is recorded and stored in temporary memory. This recorded position is the clutch friction point position that the self-learning process is looking for under the current operating condition. After recording the previous position, the clutch control does not stop, but continues to smoothly engage at a preset speed until a fully engaged position is reached. The fully engaged position means that the clutch friction plates are in contact with the engine, and the clutch can fully transmit torque in this position. The set value is a pre-calibrated number representing the minimum number of learning iterations required to obtain reliable results. Once the required number of successful learning iterations is met, the TCU reads the three recorded clutch positions from the temporary memory and then calculates the arithmetic mean of these three positions. A single learning iteration may be affected by random factors, leading to deviations in the measurement value. Taking the average value can effectively smooth out these random errors, making the final result closer to the true value. This embodiment of the invention compensates for changes in the friction point caused by clutch wear and thermal expansion, ensuring the accuracy of clutch transmission torque, while optimizing the intermediate shaft braking logic and shortening the clutch self-learning time.

[0105] An alternative implementation method, Figure 2 This is a flowchart of another control method for an intermediate shaft brake with self-learning friction point of an AMT clutch provided in an embodiment of the present invention. See also Figure 2 Based on the above embodiments, the fault diagnosis method may optionally include the following steps:

[0106] S210, The vehicle engine is idling, the transmission is in neutral, and the vehicle air pressure has reached the set value.

[0107] S220, Obtain the vehicle self-learning request.

[0108] S230. Determine whether the vehicle self-learning request is for parking clutch self-learning; if yes, execute S240; otherwise, execute S210.

[0109] S240: Obtain the real-time input shaft speed value.

[0110] S250: Determine whether the input shaft speed is greater than the preset value of the input shaft speed; if yes, proceed to S260; otherwise, proceed to S240.

[0111] S260. Determine the target inflation time array for the intermediate shaft brake based on the input shaft speed and the self-learning process of the clutch friction point.

[0112] S270, Control the clutch to disengage to the fully disengaged position.

[0113] S280: Obtain the transmission oil temperature, front auxiliary gear, intermediate shaft speed, output shaft speed, and target gear ratio under the current clutch self-learning state.

[0114] S290. Determine the base value of the intermediate shaft target deceleration rate and the compensation value of the intermediate shaft target deceleration rate.

[0115] S310, Determine the target deceleration rate of the intermediate shaft.

[0116] S320: Obtain the intermediate shaft brake inflation time array based on the transmission oil temperature and the intermediate shaft target deceleration rate.

[0117] S330, Open the intake valve of the intermediate shaft brake and close the exhaust valve at the same time.

[0118] S340: Determine if the intermediate shaft speed has dropped to the target value; if yes, execute S350; otherwise, execute S330.

[0119] S350, Close the intake valve of the intermediate shaft brake and open the exhaust valve at the same time.

[0120] S360: Control the clutch to engage at a preset speed.

[0121] S370: Obtain the deceleration rate of the transmission input shaft, the equivalent moment of inertia of the input shaft, and the acceleration rate of the transmission input shaft to determine the transmitted torque value during the clutch engagement process.

[0122] S380: Determine whether the torque transmitted by the clutch is greater than or equal to the set value of the torque transmitted by the clutch at the friction point; if yes, execute S390; otherwise, execute S370.

[0123] S390, Friction point self-learning count +1.

[0124] S410: Control the clutch to engage to the fully engaged position at a preset speed.

[0125] S420: Determine if the number of learning attempts is greater than the set value; if yes, execute S430; otherwise, execute S220.

[0126] S430. The arithmetic mean of the clutch positions recorded multiple times is taken as the clutch friction point.

[0127] This invention, through identifying the clutch self-learning phase and the normal shifting phase and selecting the intermediate shaft brake inflation time, reduces the intermediate shaft deceleration time during the clutch self-learning phase, thus avoiding the delay in engaging the starting gear after stopping caused by the intermediate shaft brake protection mechanism. Furthermore, by performing clutch self-learning in a timely manner, it compensates for changes in friction points caused by clutch wear and thermal expansion, ensuring the accuracy of clutch torque transmission. In addition, by optimizing the intermediate shaft braking logic, the total time consumed by clutch self-learning is shortened.

[0128] Optionally, Figure 3 This invention provides a control device for an intermediate shaft brake with self-learning friction point of an AMT clutch, as described in an embodiment of the present invention. Based on the above embodiment, see [link to related documentation]. Figure 3 The control device 500 for the AMT clutch friction point self-learning intermediate shaft brake provided in this embodiment of the invention includes:

[0129] The acquisition module 510 is used to acquire the transmission oil temperature and the target deceleration rate of the intermediate shaft brake.

[0130] The determination module 520 is used to determine the inflation duration of the intermediate shaft brake based on the transmission oil temperature and the target deceleration rate, and on the target inflation time array.

[0131] The inflation module 530 is used to inflate the intermediate shaft brake according to the inflation duration.

[0132] Optionally, the acquisition module 510 includes:

[0133] The acquisition unit is used to acquire the front auxiliary gearbox gear position, intermediate shaft speed, output shaft speed, front auxiliary gearbox speed ratio, and target gear ratio of the intermediate shaft brake at the moment of braking start under clutch self-learning state.

[0134] The first lookup unit determines the base value of the target deceleration rate of the intermediate shaft brake based on the intermediate shaft speed and the gear position of the front auxiliary gearbox at the moment of braking.

[0135] The first calculation unit is used to determine the target deceleration rate compensation value of the intermediate shaft based on the output shaft speed of the intermediate shaft brake, the speed ratio of the front auxiliary gearbox, and the target gear ratio.

[0136] The second calculation unit is used to determine the target deceleration rate of the intermediate shaft brake based on the sum of the base value of the target deceleration rate of the intermediate shaft brake and the compensation value of the target deceleration rate of the intermediate shaft brake.

[0137] Optionally, the first computing unit includes:

[0138] The first determining unit is used to determine the input shaft speed based on the ratio of the output shaft speed of the intermediate shaft brake to the target gear speed ratio.

[0139] The second determining unit is used to determine the target deceleration rate compensation value of the intermediate shaft based on the ratio of the input shaft speed to the front auxiliary gearbox speed.

[0140] Optionally, the determining module 520 includes:

[0141] The second lookup unit is used to determine the inflation duration of the intermediate shaft brake by looking up the target inflation time array based on the transmission oil temperature and the target deceleration rate.

[0142] Optionally, the inflation module 530 includes:

[0143] The exhaust valve closing unit is used to close the exhaust valve of the intermediate shaft brake.

[0144] The intake valve opening unit is used to open the intake valve of the intermediate shaft brake and keep the intake valve in the open state according to the inflation duration to inflate the intermediate shaft brake.

[0145] Optionally, the control device 500 for the AMT clutch friction point self-learning intermediate shaft brake provided in this embodiment of the invention further includes:

[0146] The first control module is used to control the vehicle engine to idle, the transmission to be in neutral, and the vehicle air pressure to reach the set value.

[0147] The self-learning acquisition module is used to acquire the vehicle self-learning request. When the vehicle self-learning request is for parking clutch self-learning, the input shaft speed value is acquired.

[0148] The self-learning determination module is used to determine the target inflation time array of the intermediate shaft brake based on the input shaft speed and the self-learning process of the clutch friction point when the input shaft speed value is greater than the preset value of the input shaft speed at which the clutch friction point self-learning is started.

[0149] The second control module is used to control the clutch to disengage to the fully disengaged position and to activate the intermediate shaft brake to reduce the speed of the intermediate shaft.

[0150] Optionally, the control device 500 for the AMT clutch friction point self-learning intermediate shaft brake provided in this embodiment of the invention further includes:

[0151] The current speed acquisition module is used to acquire the current speed of the intermediate shaft brake.

[0152] The third control module is used to control the inflation status of the intermediate shaft brake based on the difference between the current rotational speed and the target deceleration rate.

[0153] Optionally, the control device 500 for the AMT clutch friction point self-learning intermediate shaft brake provided in this embodiment of the invention further includes:

[0154] The fourth control module is used to control the clutch to engage at a preset speed.

[0155] The torque acquisition module is used to acquire the input shaft deceleration rate, the equivalent moment of inertia of the input shaft, and the input shaft acceleration rate of the transmission.

[0156] The torque transmission determination module is used to determine the torque value transmitted during clutch engagement based on the sum of the product of the input shaft deceleration rate and the equivalent moment of inertia of the input shaft, and the product of the equivalent moment of inertia of the input shaft and the acceleration rate of the transmission input shaft.

[0157] The position determination module is used to determine the clutch position based on the difference between the clutch's transmitted torque value and the clutch's transmitted torque set value at the friction point.

[0158] Optionally, the control device 500 for the AMT clutch friction point self-learning intermediate shaft brake provided in this embodiment of the invention further includes:

[0159] The recording module is used to record the current clutch position and increment the friction point self-learning count by 1 when the clutch transmission torque is greater than or equal to the clutch transmission torque setting value at the friction point.

[0160] The fifth control module is used to control the clutch to engage to the fully engaged position at a preset speed;

[0161] The friction point determination module is used to take the arithmetic mean of the multiple recorded clutch positions as the clutch friction point when the number of self-learning times of the clutch friction point exceeds a set value.

[0162] The control device for the intermediate shaft brake of the AMT clutch friction point self-learning system provided in this invention achieves refined control of the intermediate shaft brake through modular design. The device acquires key parameters such as transmission oil temperature and intermediate shaft speed precisely through an acquisition module. Combined with a lookup table logic based on a target inflation time array, the determination module dynamically matches the inflation time. The inflation module then performs the inflation operation on the intermediate shaft brake. This process considers both the influence of oil temperature on braking response and the target deceleration rate requirement, effectively solving the problem of excessively long braking time or over-braking caused by time lag in traditional pneumatic control. It ensures that the intermediate shaft speed can smoothly decrease to the target value according to the self-learning requirements, providing a stable benchmark condition for friction point learning.

[0163] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A control method for an intermediate shaft brake with self-learning friction point of an AMT clutch, characterized in that, include: Obtain the transmission oil temperature and the target deceleration rate of the intermediate shaft brake; Based on the transmission oil temperature and the target deceleration rate, and using the target inflation time array, the inflation duration of the intermediate shaft brake is determined. The intermediate shaft brake is inflated according to the inflation duration.

2. The control method according to claim 1, characterized in that, Before obtaining the transmission oil temperature and the target deceleration rate of the intermediate shaft brake, the following steps are also included: Under the clutch self-learning state, the intermediate shaft brake at the moment of braking start is obtained as follows: front auxiliary gearbox gear position, intermediate shaft speed, output shaft speed, front auxiliary gearbox speed ratio, and target gear ratio. Based on the intermediate shaft speed and the gear position of the front auxiliary gearbox at the moment of braking start, determine the basic value of the target deceleration rate of the intermediate shaft brake; The target deceleration rate compensation value of the intermediate shaft is determined based on the output shaft speed of the intermediate shaft brake, the speed ratio of the front auxiliary gearbox, and the target gear ratio. The target deceleration rate of the intermediate shaft brake is determined based on the sum of the base value of the target deceleration rate of the intermediate shaft brake and the compensation value of the target deceleration rate of the intermediate shaft brake.

3. The control method according to claim 2, characterized in that, The step of determining the target deceleration rate compensation value of the intermediate shaft based on the output shaft speed of the intermediate shaft brake, the speed ratio of the front auxiliary gearbox, and the target gear ratio includes: The input shaft speed is determined based on the ratio of the output shaft speed of the intermediate shaft brake to the target gear ratio; The target deceleration rate compensation value of the intermediate shaft is determined based on the ratio of the input shaft speed to the front auxiliary gearbox speed ratio.

4. The control method according to any one of claims 1 to 3, characterized in that, The step of determining the inflation duration of the intermediate shaft brake based on the transmission oil temperature and the target deceleration rate, and using a target inflation time array, includes: Based on the target inflation time array, the inflation time of the intermediate shaft brake is determined by looking up a table according to the transmission oil temperature and the target deceleration rate.

5. The control method according to claim 1, characterized in that, The step of inflating the intermediate shaft brake according to the inflation duration includes: Close the exhaust valve of the intermediate shaft brake; Open the air intake valve of the intermediate shaft brake and keep the air intake valve in the open state according to the inflation duration to inflate the intermediate shaft brake.

6. The control method according to claim 2 or 3, characterized in that, Before determining the inflation duration of the intermediate shaft brake based on the transmission oil temperature and the target deceleration rate, and using a target inflation time array, the method further includes: The vehicle engine is kept at idle speed, the transmission is in neutral, and the vehicle air pressure reaches the set value. Obtain the vehicle self-learning request. When the vehicle self-learning request is for parking clutch self-learning, obtain the input shaft speed value. When the input shaft speed is greater than the preset input shaft speed for the clutch friction point self-learning start, the target inflation time array of the intermediate shaft brake is determined according to the input shaft speed and the clutch friction point self-learning process. Control the clutch to disengage to the fully disengaged position and activate the intermediate shaft brake to reduce the speed of the intermediate shaft.

7. The control method according to claim 1, characterized in that, After inflating the intermediate shaft brake according to the inflation duration, the method further includes: Obtain the current rotational speed of the intermediate shaft brake; The inflation state of the intermediate shaft brake is controlled based on the difference between the current rotational speed and the target deceleration rate.

8. The control method according to claim 7, characterized in that, After controlling the inflation state of the intermediate shaft brake based on the difference between the current rotational speed and the target deceleration rate, the method further includes: Control the clutch to engage at a preset speed; Obtain the input shaft deceleration rate, the equivalent moment of inertia of the input shaft, and the input shaft acceleration rate of the transmission. The torque value transmitted during the clutch engagement process is determined by summing the product of the input shaft deceleration rate and the equivalent moment of inertia of the input shaft with the product of the equivalent moment of inertia of the input shaft and the acceleration rate of the transmission input shaft. The clutch position is determined based on the difference between the torque value transmitted by the clutch and the set torque value transmitted by the clutch at the friction point.

9. The control method according to claim 8, characterized in that, Determining the clutch position based on the difference between the clutch's transmitted torque value and the clutch's set transmitted torque value at the friction point includes: When the clutch transmission torque is greater than or equal to the set value of the clutch transmission torque at the friction point, record the current clutch position and increment the friction point self-learning count by 1. Control the clutch to engage at a preset speed until it is fully engaged; When the number of self-learning times of the clutch friction point exceeds the set value, the arithmetic mean of the multiple recorded clutch positions is taken as the clutch friction point.

10. A control device for an intermediate shaft brake with self-learning friction point of an AMT clutch, characterized in that, include: The acquisition module is used to acquire the transmission oil temperature and the target deceleration rate of the intermediate shaft brake. The determination module is used to determine the inflation duration of the intermediate shaft brake based on the transmission oil temperature and the target deceleration rate, and on a target inflation time array. An inflation module is used to inflate the intermediate shaft brake according to the inflation duration.

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