An at transmission power downshift shift control method, system and apparatus
By calculating the overspeed risk index and constructing a dynamic synchronization protection band, the system achieves predictive and corrective torque reduction during the downshifting process of the AT transmission, solving the problems of engine speed instability and excessive slippage work, and improving the smoothness and stability of gear shifting.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- FAW QI NEW POWER (CHANGCHUN) TECHNOLOGY CO LTD
- Filing Date
- 2026-04-29
- Publication Date
- 2026-06-09
AI Technical Summary
In existing automatic transmissions, engine speed is prone to instability during downshifting, resulting in a significant increase in slippage work and large fluctuations in shift shock. Existing control methods have failed to effectively solve the speed synchronization problem.
By calculating the overspeed risk index, predicting and correcting torque reduction requests, and constructing a dynamic synchronous protection zone, the engine torque can be adjusted in multiple dimensions and the speed can be actively corrected, forming a closed-loop control, reducing slippage work and heat load, and improving shift smoothness.
It effectively reduces speed overshoot, lowers clutch slippage work, and improves shift smoothness and stability, especially performing excellently in complex scenarios such as high torque and low adhesion.
Smart Images
Figure CN122170226A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of automatic transmission control technology, and particularly relates to a method, system and device for power downshifting control of an AT transmission. Background Technology
[0002] When an AT transmission is downshifting, the shifting process requires torque exchange and speed synchronization. Existing engine speed control generally adopts a fixed torque reduction strategy, which sets a fixed torque reduction value only based on the shift type, target gear and current gear, without considering the real-time torque fluctuation of the engine. Speed synchronization is achieved solely through closed-loop control of clutch pressure.
[0003] The above control method has obvious defects: when the actual engine torque fluctuation exceeds the set value, the speed is prone to instability, i.e., speed runaway; the clutch needs to passively compensate for the speed difference, resulting in a significant increase in slippage work; the shift shock fluctuation is greatly affected by the engine torque control accuracy, resulting in poor shift smoothness.
[0004] Therefore, there is an urgent need for an AT transmission power downshift engine torque reduction control method that can intervene in advance, adjust in multiple dimensions, and actively correct for speed spikes, in order to solve the problems of speed instability, large slippage work, and obvious shift shock in the existing technology. Summary of the Invention
[0005] To address the shortcomings of existing technologies, this invention proposes a power downshift control method, system, and device for automatic transmissions, which enables early intervention of engine torque, multi-dimensional torque reduction calculation, active correction of overspeed, and smooth recovery, thereby improving shift quality.
[0006] The objective of this invention is achieved through the following technical solution:
[0007] In one aspect, the present invention provides a power downshift control method for an automatic transmission, comprising:
[0008] The speed-off risk index is calculated based on the deviation between the real-time engine speed and the current gear clutch speed, the deviation between the change in engine speed and the change in the current gear clutch speed, and the change in engine torque.
[0009] Before shifting gears into the speed regulation phase, it is determined whether the speed risk index has reached the prediction trigger threshold. If so, a prediction torque reduction request is generated based on the speed risk index and the prediction trigger threshold.
[0010] After entering the gear shifting and speed adjustment stage, the basic torque reduction request is determined based on multi-dimensional parameters, and a synchronous protection zone is constructed based on the real-time changes of the current gear clutch speed and the target gear clutch speed.
[0011] Determine whether the engine speed exceeds the upper boundary of the synchronization protection band, or whether the overspeed risk index reaches the correction trigger threshold. If so, generate a correction torque reduction request.
[0012] The minimum value among the basic torque reduction request, the predicted torque reduction request, and the corrected torque reduction request is selected as the engine torque limiting request, and the engine output torque is controlled according to the engine torque limiting request; when the predicted torque reduction request or the corrected torque reduction request exits, a recovery hysteresis condition is set, and when the recovery hysteresis condition is met, the system returns to the basic torque reduction request.
[0013] Optionally, the recovery hysteresis condition includes: the engine speed falls within the synchronization protection zone, and the speed risk index is not greater than the release threshold, and the duration is not less than the preset holding time.
[0014] Optionally, the calculation of the high-speed rotation risk index includes:
[0015] The difference between the engine speed and the clutch speed of the current gear is weighted and normalized to obtain the first component;
[0016] The difference between the engine speed change and the clutch speed change in the current gear is weighted and normalized to obtain the second component.
[0017] The engine torque variation is weighted and normalized to obtain the third component;
[0018] The first component, the second component, and the third component are summed to determine the speed risk index.
[0019] Optionally, generating the predicted torque reduction request based on the high-speed risk index and the predicted trigger threshold includes:
[0020] Calculate the difference between the speed-up risk index and the predicted trigger threshold;
[0021] Based on the product of the difference and the first calibration coefficient, and the product of the engine target torque and the second calibration coefficient, the predicted torque reduction is calculated, and a predicted torque reduction request is generated.
[0022] Optionally, the multidimensional parameters include engine speed, clutch speed, engine target torque, and shift type.
[0023] Optionally, the construction of the synchronization protection band includes:
[0024] Calculate the sum of the clutch speed of the current gear and the speed difference between the target gear and the current gear, multiply it by the first proportional coefficient, and determine the difference between it and the first correction amount, which is defined as the lower boundary of the synchronous protection band;
[0025] Calculate the difference between the target gear speed and the current gear speed, multiply it by the second proportional coefficient, and then add it to the second correction amount to obtain the upper boundary of the synchronous protection zone;
[0026] Wherein, the first proportional coefficient is greater than 0 and less than the second proportional coefficient, and the second proportional coefficient is less than 1.
[0027] Optionally, generating the torque reduction correction request includes: calculating the product of the amount by which the engine speed exceeds the upper boundary of the protection zone and a first correction coefficient, multiplying the difference between the engine speed change and the reference speed change by a second correction coefficient, and adding the engine target torque multiplied by a third correction coefficient to calculate the torque reduction correction and generate the torque reduction correction request.
[0028] Optionally, the method further includes: before shifting gears to enter the speed regulation phase, performing torque increase rate limit control: when the change in engine torque exceeds a preset increase rate limit, each control cycle only allows the torque to increase by a preset allowable increment.
[0029] In another aspect, the present invention provides an automatic transmission power downshift control system, the system comprising:
[0030] The risk index calculation module is used to calculate the speed risk index based on the deviation between the engine speed and the current gear clutch speed, the deviation between the change in engine speed and the change in the current gear clutch speed, and the change in engine torque.
[0031] The torque reduction prediction module is used to determine whether the high speed risk index has reached the prediction trigger threshold before shifting to the speed regulation stage. If so, a torque reduction prediction request is generated based on the high speed risk index and the prediction trigger threshold.
[0032] The protective belt construction module is used to determine the basic torque reduction request based on multi-dimensional parameters after entering the gear shifting and speed adjustment stage, and to construct a synchronous protective belt based on the real-time changes of the current gear clutch speed and the target gear clutch speed.
[0033] The torque reduction correction module is used to determine whether the engine speed exceeds the upper boundary of the synchronization protection band, or whether the speed risk index reaches the correction trigger threshold. If so, a torque reduction correction request is generated.
[0034] The recovery control module is used to select the minimum value among the basic torque reduction request, the predicted torque reduction request, and the corrected torque reduction request as the engine torque limiting request, and control the engine output torque according to the engine torque limiting request; when the predicted torque reduction request or the corrected torque reduction request exits, a recovery hysteresis condition is set, and when the recovery hysteresis condition is met, the system recovers to the basic torque reduction request.
[0035] A third aspect of the present invention provides an electronic device including a memory and a processor, wherein the memory stores a computer program that, when executed by the processor, causes the processor to perform the steps of the method as described in any one of the first aspects.
[0036] Compared with the closest prior art, the present invention has the following beneficial effects:
[0037] The present invention provides an AT transmission power downshift control method, system and equipment, which uses the overspeed risk index to predict trends and intervenes before the speed soars, fundamentally reducing the peak value of speed overshoot and making the speed adjustment process smoother.
[0038] In this invention, the engine side actively assumes the primary responsibility for mitigating synchronization risks, preventing the clutch from passively increasing transmitted torque due to catching up with synchronization. This effectively reduces slippage work and thermal load, extending clutch life. The use of a dynamic synchronization protection band and recovery hysteresis mechanism allows the control boundary to adaptively adjust with operating conditions and avoids frequent switching of control quantities near critical states, significantly improving the consistency of shift quality, making it particularly suitable for complex scenarios such as high torque and low adhesion.
[0039] This invention establishes a new mode of "engine-clutch" coordinated control, forming a complete control closed loop from limiting torque increase, predicting torque decrease, correcting torque decrease to hysteresis recovery, which has significant inventiveness. Attached Figure Description
[0040] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.
[0041] Figure 1 A flowchart of an AT transmission power downshift control method provided by the present invention;
[0042] Figure 2 The present invention provides a flowchart for preventing engine torque from rising too quickly and causing engine speed to spike.
[0043] Figure 3 This is a schematic diagram of the control method provided by the present invention to prevent the engine speed from skyrocketing due to excessively rapid increase in engine torque;
[0044] Figure 4 A flowchart of the torque reduction request process in the engine speed regulation process provided by the present invention;
[0045] Figure 5 This is a schematic diagram illustrating a torque reduction request during engine speed regulation when a runaway engine occurs, as provided by the present invention.
[0046] Figure 6 A schematic diagram of the structure of an AT transmission power downshift control system provided by the present invention;
[0047] Figure 7 This is a schematic diagram of the electronic device structure used to implement the methods and system embodiments of this application. Detailed Implementation
[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0049] Example 1: Example 1 of this invention proposes a power downshift control method for an automatic transmission (AT), specifically involving a method for controlling engine output torque during power downshifting in an AT transmission. By constructing a closed-loop control link of "pre-prediction - in-process correction - post-smooth recovery," the engine actively assumes synchronization risks, significantly suppresses speed overshoot, reduces clutch slippage work, and improves shift smoothness and control stability. Figure 1 As shown, the method specifically includes the following steps:
[0050] Step S101: Calculate the overspeed risk index based on the real-time deviation between the engine speed and the current gear clutch speed, the deviation between the engine speed change and the current gear clutch speed change, and the engine torque change.
[0051] Step S102: Before shifting gears into the speed regulation stage, determine whether the high speed risk index has reached the prediction trigger threshold. If so, generate a prediction torque reduction request based on the high speed risk index and the prediction trigger threshold.
[0052] Step S103: After entering the gear shifting and speed adjustment stage, the basic torque reduction request is determined according to the multi-dimensional parameters, and a synchronous protection band is constructed based on the real-time changes of the current gear clutch speed and the target gear clutch speed.
[0053] Step S104: Determine whether the engine speed exceeds the upper boundary of the synchronization protection band, or whether the speed risk index reaches the correction trigger threshold. If so, generate a correction torque reduction request.
[0054] Step S105: Select the minimum value among the basic torque reduction request, the predicted torque reduction request, and the corrected torque reduction request as the engine torque limiting request, and control the engine output torque according to the engine torque limiting request; when the predicted torque reduction request or the corrected torque reduction request exits, set a recovery hysteresis condition, and when the recovery hysteresis condition is met, return to the basic torque reduction request.
[0055] In step S101 above, calculating the speed-up risk index includes:
[0056] The difference between the engine speed and the clutch speed of the current gear is weighted and normalized to obtain the first component;
[0057] The difference between the engine speed change and the clutch speed change in the current gear is weighted and normalized to obtain the second component.
[0058] The engine torque variation is weighted and normalized to obtain the third component;
[0059] The first component, the second component, and the third component are summed to determine the speed risk index.
[0060] In step S102 above, generating a predicted torque reduction request based on the high-speed risk index and the predicted trigger threshold includes:
[0061] Calculate the difference between the speed-up risk index and the predicted trigger threshold;
[0062] Based on the product of the difference and the first calibration coefficient, and the product of the engine target torque and the second calibration coefficient, the predicted torque reduction is calculated, and a predicted torque reduction request is generated.
[0063] In step S103 above, the multidimensional parameters include engine speed, clutch speed, engine target torque, and shift type.
[0064] The construction of the synchronous protection band includes:
[0065] Calculate the sum of the clutch speed of the current gear and the speed difference between the target gear and the current gear, multiply it by the first proportional coefficient, and determine the difference between it and the first correction amount, which is defined as the lower boundary of the synchronous protection band;
[0066] Calculate the difference between the target gear speed and the current gear speed, multiply it by the second proportional coefficient, and then add it to the second correction amount to obtain the upper boundary of the synchronous protection zone;
[0067] Wherein, the first proportional coefficient is greater than 0 and less than the second proportional coefficient, and the second proportional coefficient is less than 1.
[0068] In step S104 above, generating the torque reduction correction request includes: calculating the product of the amount by which the engine speed exceeds the upper boundary of the protection zone and the first correction coefficient, multiplying the difference between the engine speed change and the reference speed change by the second correction coefficient, and adding the engine target torque multiplied by the third correction coefficient to calculate the torque reduction correction and generate the torque reduction correction request.
[0069] In step S105 above, the recovery hysteresis condition includes: the engine speed falls within the synchronization protection zone, and the speed risk index is not greater than the release threshold, and the duration is not less than the preset holding time.
[0070] The method further includes: before shifting gears to enter the speed regulation stage, performing torque increase rate limit control: when the change in engine torque exceeds the preset increase rate limit, each control cycle only allows the torque to increase by a preset allowable increment.
[0071] Example 2: This example illustrates the situation where the vehicle is in a downshifting mode and the transmission shifts from the current gear (e.g., 4th gear) to the target gear (e.g., 3rd gear).
[0072] Step 1: Gear Shift Recognition and Preparation
[0073] The vehicle control unit (TCU) detects the driver's large throttle opening and determines that a downshift is required. The TCU issues a shift command and enters the preparation phase. First, it controls the disengaging clutch (the clutch that is disengaging) and engaging clutch (the clutch that will be engaged) to complete the lubrication process and eliminate the clutch free travel.
[0074] Step 2: First Stage—Pre-intervention Torque Control (e.g.) Figure 2 , Figure 3 )
[0075] After oil filling is complete, the torque exchange phase begins. At this time, engine torque starts to transfer from the disengaged clutch to the engaged clutch. To prevent the engine torque from rising too quickly, the controller performs pre-intervention control.
[0076] The controller acquires the actual engine torque T at fixed intervals (e.g., 10ms). eng (k), engine speed n eng (k) Current gear clutch speed n cur The torque change ΔT is calculated from signals such as (k) (i.e., the speed of the disengaged clutch drive disc) eng (k)=T eng (k)−T eng (k-1) If ΔT eng (k)>ΔT limi (For example, 50 Nm / cycle), then the torque limit increase control is activated, allowing only a torque increase of ΔT per cycle. allo(e.g., 5 Nm), to obtain the torque limit T. limit (k). For example... Figure 2 As shown, the engine torque is limited to a gently rising curve.
[0077] Simultaneously, the speed-up risk index is calculated in parallel. In this embodiment, the calibration parameters are as follows:
[0078] ω1=0.45, ω2=0.30, ω3=0.25; normalization coefficients N1=150rpm, N2=80rpm, N3=40.
[0079] Assuming the current period measures n eng (k)−n cur (k) = 80 rpm, Δn eng (k)−Δn cur (k) = 30 rpm, T eng (k) = 20 Nm, then the calculation yields:
[0080] R(k)=0.45×80 / 150+0.30×30 / 80+0.25×20 / 40=0.24+0.1125+0.125=0.4775
[0081] Let the prediction trigger threshold T be... pre (k)=K r ⋅(R(k)-R pre )+K t ⋅T target (k)
[0082] The request was sent to the Engine Management Unit (EMS) to impose stricter limits on the torque ramp-up rate in advance.
[0083] Step 3: Second Stage—Speed Regulation Stage and Dynamic Protection (corresponding to...) Figure 4 , Figure 5 )
[0084] With torque exchange complete, the gear shift enters the speed adjustment phase. At this point, the clutch engages, requiring the engine speed to be adjusted from the speed n corresponding to the current gear. cur (k) Synchronize to the speed n corresponding to the target gear. tar (k) (4th gear down to 3rd gear, n) tar (k)>n cur (k)); The controller first determines based on n clutch ,T target ,Shift_Type checks the preset calibration map to obtain the basic torque reduction request T base (k).
[0085] Simultaneously, a dynamic synchronous protection band is constructed. Let α = 0.35, β = 0.75, B1 = 20 rpm, B2 = 30 rpm; then: ;
[0086] The protective band dynamically shifts to the right as the synchronization process progresses, providing an "allowable fluctuation range" for engine speed.
[0087] Suppose that during the mid-speed adjustment range, due to some disturbance, the engine speed rapidly increases, and n is detected. eng (k) = 2800 rpm, and the calculated n high (k) = 2750 rpm. At this time, n eng (k)>n high (k) satisfies, or even if it does not exceed the upper boundary but R(k)≥R corr (Let R) corr If the value is 0.65, then the torque reduction control is immediately triggered. Calculate the torque reduction amount: ;
[0088] This torque reduction acts directly on the engine, forcibly reducing torque output, such as Figure 4 As shown, the upward trend of engine speed was quickly contained and began to decline.
[0089] Step 4: Final Request Generation
[0090] In each control cycle, the controller calculates T base (k), T pre (k), T coor (k), and take the minimum of the three as the final request. In this example, T coor (k) is the smallest, so the engine performs torque reduction according to this strong constraint.
[0091] Step 5: Hysteresis Recovery and Smooth Transition
[0092] When the engine speed drops, n is satisfied. eng (k)∈[n high (k),n low [(k)], and the risk index R(k)≤R rel (e.g. R) rel =0.3), and after a period of time, the hysteresis condition is met. The controller does not immediately switch back to the basic torque reduction, but instead enters the recovery phase. The torque is smoothly released according to the following formula: ;
[0093] Let Δ rec If the torque is reduced to 5Nm, the torque recovery in each cycle will not exceed 5Nm, effectively preventing a second speed rebound caused by excessively rapid torque recovery. Ultimately, the engine torque smoothly returns to the base torque reduction value until the speed adjustment is complete and the gear shift ends.
[0094] Through the above process, the present invention achieves full-chain active control of engine torque reduction, namely "trend prediction - dynamic range correction - smooth recovery", which significantly improves the shifting quality of power downshifting.
[0095] Example 3: Based on the same technical concept as the above method, Example 3 of the present invention provides an AT transmission power downshift control system, which includes: a risk index calculation module 210, a torque reduction prediction module 220, a protection band construction module 230, a torque reduction correction module 240, and a recovery control module 250 connected in sequence. Each module can be deployed on the same computing device or distributed, communicating via a network interface. Figure 6 As shown, the connections between the modules are illustrated.
[0096] Specifically, the system includes:
[0097] The risk index calculation module 210 is used to calculate the speed risk index based on the deviation between the engine speed and the current gear clutch speed, the deviation between the change in engine speed and the change in the current gear clutch speed, and the change in engine torque.
[0098] The torque reduction prediction module 220 is used to determine whether the high speed risk index has reached the prediction trigger threshold before shifting to the speed regulation stage. If so, it generates a predicted torque reduction request based on the high speed risk index and the prediction trigger threshold.
[0099] The protection belt construction module 230 is used to determine the basic torque reduction request based on multi-dimensional parameters after entering the gear shifting and speed adjustment stage, and to construct a synchronous protection belt based on the real-time changes of the current gear clutch speed and the target gear clutch speed.
[0100] The torque reduction correction module 240 is used to determine whether the engine speed exceeds the upper boundary of the synchronization protection band, or whether the speed risk index reaches the correction trigger threshold. If so, a torque reduction correction request is generated.
[0101] The recovery control module 250 is used to select the minimum value among the basic torque reduction request, the predicted torque reduction request, and the corrected torque reduction request as the engine torque limiting request, and control the engine output torque according to the engine torque limiting request; when the predicted torque reduction request or the corrected torque reduction request exits, a recovery hysteresis condition is set, and when the recovery hysteresis condition is met, the system returns to the basic torque reduction request.
[0102] Example 4: This embodiment of the invention also provides an electronic device corresponding to Example 1. The electronic device includes a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it causes the processor to perform the steps of any one of the methods described in S101-S105.
[0103] like Figure 7 As shown, the electronic device may include: at least one processor 31, at least one network interface 35, user interface 34, memory 36, and at least one communication bus 32.
[0104] The communication bus 32 is used to enable communication between these components.
[0105] The user interface 34 may include a display screen and a camera. Optionally, the user interface 34 may also include a standard wired interface and a wireless interface.
[0106] The network interface 35 may optionally include a standard wired interface or a wireless interface (such as a WIFI interface).
[0107] The processor 31 may include one or more processing cores. The processor 31 connects to various parts of the server using various interfaces and lines, and performs various server functions and processes data by running or executing instructions, programs, code sets, or instruction sets stored in the memory 36, and by calling data stored in the memory 36. Optionally, the processor 31 may be implemented using at least one hardware form of Digital Signal Processing (DSP), Field-Programmable Gate Array (FPGA), or Programmable Logic Array (PLA). The processor 31 may integrate one or a combination of several of the following: Central Processing Unit (CPU), Graphics Processing Unit (GPU), and modem. The CPU primarily handles the operating system, user interface, and applications; the GPU is responsible for rendering and drawing the content required for display; and the modem handles wireless communication. It is understood that the modem may also not be integrated into the processor 31 and may be implemented as a separate chip.
[0108] The memory 36 may include random access memory (RAM) or read-only memory. Optionally, the memory 36 may include a non-transitory computer-readable storage medium. The memory 36 can be used to store instructions, programs, code, code sets, or instruction sets. The memory 36 may include a program storage area and a data storage area, wherein the program storage area may store instructions for implementing an operating system, instructions for at least one function (such as touch function, sound playback function, image playback function, etc.), instructions for implementing the above-described method embodiments, etc.; the data storage area may store data involved in the above-described method embodiments, etc. Optionally, the memory 36 may also be at least one storage device located remotely from the aforementioned processor 31. Figure 7 As shown, the memory 36, which serves as a computer storage medium, may include an operating system, a network communication module, a user interface module, and an AT transmission power downshift control method and system.
[0109] exist Figure 7 In the electronic device shown, the user interface 34 is mainly used to provide an input interface for the user and to obtain the user input data; while the processor 31 can be used to call the application program of an AT transmission power downshift control method stored in the memory 36. When executed by one or more processors 31, the electronic device executes one or more of the AT transmission power downshift control methods described in steps S101-S105 of the above embodiments.
[0110] Those skilled in the art will clearly understand that the technical solutions of this application can be implemented using software and / or hardware. In this specification, "module" refers to software and / or hardware capable of independently performing or cooperating with other components to perform a specific function. Hardware may include, for example, a Field-Programmable Gate Array (FPGA), an Integrated Circuit (IC), etc.
[0111] Specifically, the processor can be a Central Processing Unit (CPU), but it can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor.
[0112] The code of the computer program can be in the form of source code, object code, executable file, or some intermediate form.
[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.
Claims
1. A method for controlling downshifting in an automatic transmission (AT), characterized in that, The method includes: The speed-off risk index is calculated based on the deviation between the real-time engine speed and the current gear clutch speed, the deviation between the change in engine speed and the change in the current gear clutch speed, and the change in engine torque. Before shifting gears into the speed regulation phase, it is determined whether the speed risk index has reached the prediction trigger threshold. If so, a prediction torque reduction request is generated based on the speed risk index and the prediction trigger threshold. After entering the gear shifting and speed adjustment stage, the basic torque reduction request is determined based on multi-dimensional parameters, and a synchronous protection zone is constructed based on the real-time changes of the current gear clutch speed and the target gear clutch speed. Determine whether the engine speed exceeds the upper boundary of the synchronization protection band, or whether the overspeed risk index reaches the correction trigger threshold. If so, generate a correction torque reduction request. The minimum value among the basic torque reduction request, the predicted torque reduction request, and the corrected torque reduction request is selected as the engine torque limiting request, and the engine output torque is controlled according to the engine torque limiting request; when the predicted torque reduction request or the corrected torque reduction request exits, a recovery hysteresis condition is set, and when the recovery hysteresis condition is met, the system returns to the basic torque reduction request.
2. The method according to claim 1, characterized in that, The recovery hysteresis conditions include: the engine speed falls within the synchronization protection zone, the overspeed risk index is not greater than the release threshold, and the duration is not less than the preset holding time.
3. The method according to claim 1, characterized in that, The calculation of the speed-flying risk index includes: The difference between the engine speed and the clutch speed of the current gear is weighted and normalized to obtain the first component; The difference between the engine speed change and the clutch speed change in the current gear is weighted and normalized to obtain the second component. The engine torque variation is weighted and normalized to obtain the third component; The first component, the second component, and the third component are summed to determine the speed risk index.
4. The method according to claim 3, characterized in that, The process of generating a predicted torque reduction request based on the high-speed risk index and the predicted trigger threshold includes: Calculate the difference between the speed-up risk index and the predicted trigger threshold; Based on the product of the difference and the first calibration coefficient, and the product of the engine target torque and the second calibration coefficient, the predicted torque reduction is calculated, and a predicted torque reduction request is generated.
5. The method according to claim 1, characterized in that, The multidimensional parameters include engine speed, clutch speed, engine target torque, and shift type.
6. The method according to claim 1, characterized in that, The construction of the synchronous protection band includes: Calculate the sum of the clutch speed of the current gear and the speed difference between the target gear and the current gear, multiply it by the first proportional coefficient, and determine the difference between it and the first correction amount, which is defined as the lower boundary of the synchronous protection band; Calculate the difference between the target gear speed and the current gear speed, multiply it by the second proportional coefficient, and then add it to the second correction amount to obtain the upper boundary of the synchronous protection zone; Wherein, the first proportional coefficient is greater than 0 and less than the second proportional coefficient, and the second proportional coefficient is less than 1.
7. The method according to claim 1, characterized in that, The process of generating a torque reduction correction request includes: calculating the product of the amount by which the engine speed exceeds the upper boundary of the protection zone and a first correction coefficient, multiplying the difference between the engine speed change and the reference speed change by a second correction coefficient, and adding the engine target torque multiplied by a third correction coefficient to obtain the torque reduction correction and generate the torque reduction correction request.
8. The method according to claim 1, characterized in that, The method further includes: before shifting gears to enter the speed regulation stage, performing torque increase rate limit control: when the change in engine torque exceeds the preset increase rate limit, each control cycle only allows the torque to increase by a preset allowable increment.
9. A power downshift control system for an automatic transmission, characterized in that, The system includes: The risk index calculation module is used to calculate the speed risk index based on the deviation between the engine speed and the current gear clutch speed, the deviation between the change in engine speed and the change in the current gear clutch speed, and the change in engine torque. The torque reduction prediction module is used to determine whether the high speed risk index has reached the prediction trigger threshold before shifting to the speed regulation stage. If so, a torque reduction prediction request is generated based on the high speed risk index and the prediction trigger threshold. The protective belt construction module is used to determine the basic torque reduction request based on multi-dimensional parameters after entering the gear shifting and speed adjustment stage, and to construct a synchronous protective belt based on the real-time changes of the current gear clutch speed and the target gear clutch speed. The torque reduction correction module is used to determine whether the engine speed exceeds the upper boundary of the synchronization protection band, or whether the speed risk index reaches the correction trigger threshold. If so, a torque reduction correction request is generated. The recovery control module is used to select the minimum value among the basic torque reduction request, the predicted torque reduction request, and the corrected torque reduction request as the engine torque limiting request, and control the engine output torque according to the engine torque limiting request; when the predicted torque reduction request or the corrected torque reduction request exits, a recovery hysteresis condition is set, and when the recovery hysteresis condition is met, the system recovers to the basic torque reduction request.
10. An electronic device, comprising a memory and a processor, characterized in that, The memory stores a computer program that, when executed by the processor, causes the processor to perform the steps of the method as described in any one of claims 1 to 8.