Cvt transmission speed overshoot control method and device, vehicle and storage medium

Abstract

The application relates to the technical field of continuously variable transmission (CVT) control, in particular to a CVT gearbox speed overshoot control method and device, a vehicle and a storage medium, the method comprising the following steps: when a vehicle appears a speed overshoot risk, determining a CVT target allowable speed according to an actual throttle opening degree and a vehicle speed; after a difference value between a current speed and the target allowable speed reaches a gear shifting threshold, selecting a target virtual gear position through the actual vehicle speed, calculating a final speed ratio through a pulley simulation speed ratio of the gear position, controlling a master-slave pulley oil pressure locking speed ratio according to the final speed ratio, sending an instruction by a gearbox controller to adjust an engine output torque, and restraining the speed to a safety range, so that the CVT speed overshoot is inhibited. Therefore, the problems in the prior art that the engine is prone to overspeed operation, power output drops, the acceleration stability of the vehicle under a full-load working condition cannot be guaranteed, and the vehicle power experience and NVH performance are reduced are solved.

Description

Technical Field

[0001] This application relates to the field of continuously variable transmission (CVT) control technology, and in particular to a CVT (Continuously Variable Transmission) transmission speed overshoot control method, device, vehicle, and storage medium. Background Technology

[0002] In related technologies, in the control of continuously variable transmissions (CVTs), the target speed, i.e., the shift point, corresponds to the target gear ratio. The CVT adjusts the gear ratio by controlling the hydraulic pressure. During the transmission control process, due to issues with hydraulic system pressure control and response, the actual gear ratio cannot perfectly follow the target gear ratio, resulting in a slight difference and a certain deviation between the actual and target speeds. This is more pronounced at high speeds, causing engine overspeed, reduced output torque, impaired acceleration performance, and accompanied by significant engine noise.

[0003] Therefore, the relevant technologies are prone to causing abnormal overspeeding of the engine, with the engine operating conditions deviating from the optimal torque range and the power output continuously decreasing. It is impossible to achieve synchronous adjustment of the actual gear ratio of the transmission to follow the target gear ratio under full-speed and full-load acceleration conditions, making it difficult to stably control the engine operating speed. This significantly reduces the vehicle's acceleration response performance and cabin quietness, affecting the user's driving experience, and urgently needs to be solved. Summary of the Invention

[0004] This application provides a CVT transmission speed overshoot control method, device, vehicle, and storage medium to solve problems in related technologies, such as easy engine overspeeding, power output decline, inability to guarantee vehicle acceleration stability under full load conditions, and reduced vehicle power experience and NVH (Noise, Vibration, Harshness) performance.

[0005] The first aspect of this application provides a CVT transmission speed overshoot control method, comprising the following steps: when a target vehicle is in a risky condition of transmission speed overshoot, determining the target permissible speed of the CVT of the target vehicle based on the actual accelerator pedal opening and the actual vehicle speed; responding to the speed difference between the current speed of the CVT and the target permissible speed satisfying the target gear shifting condition, determining the target virtual gear of the CVT using the actual vehicle speed; determining the final gear ratio of the CVT using the simulated speed ratio of the pulleys of the CVT corresponding to the target virtual gear; controlling the working oil pressure of the input pulley and output pulley of the CVT to maintain a target lock-up state based on the final gear ratio; and adjusting the engine output torque of the target vehicle based on the torque control command issued by the transmission controller of the target vehicle to obtain an engine speed that meets a preset safety state, thereby controlling the overshoot of the CVT transmission speed.

[0006] Optionally, in one embodiment of this application, determining the target permissible speed of the continuously variable transmission (CVT) of the target vehicle based on the actual accelerator pedal opening and the actual vehicle speed includes: generating a shift speed map of the CVT based on multiple accelerator pedal opening parameters and vehicle speed parameters; and determining the target permissible speed of the CVT based on the shift speed map using the actual accelerator pedal opening and the actual vehicle speed.

[0007] Optionally, in one embodiment of this application, determining the target virtual gear of the CVT using the actual vehicle speed includes: calculating the speed difference based on the current speed of the CVT and the target allowable speed; when the speed difference is detected to be greater than or equal to a preset threshold, determining that the target gear shifting condition is met, and using the actual vehicle speed to match a pre-set CVT virtual gear table to determine the target virtual gear of the CVT.

[0008] Optionally, in one embodiment of this application, the step of controlling the working oil pressure of the input pulley and output pulley of the CVT to maintain a target lock-up state according to the final speed ratio includes: determining the target lock-up oil pressure corresponding to the input pulley and output pulley according to the final speed ratio; and allocating the corresponding target lock-up oil pressure to the input pulley and output pulley so that the working oil pressure of the input pulley and output pulley maintains a target lock-up state.

[0009] Optionally, in one embodiment of this application, after controlling the overshoot of the CVT transmission speed, the method further includes: after detecting that the engine speed of the target vehicle has been adjusted to a preset safe speed range, removing the working oil pressure of the input pulley and output pulley from the locked state, and restoring the continuously variable transmission adjustment of the CVT.

[0010] A second aspect of this application provides a CVT transmission speed overshoot control device, comprising: a first determining module, configured to determine the target permissible speed of the continuously variable transmission (CVT) of the target vehicle based on the actual accelerator pedal opening and the actual vehicle speed when the target vehicle is in a risky condition of transmission speed overshoot; a second determining module, configured to determine the target virtual gear of the CVT using the actual vehicle speed in response to the speed difference between the current speed of the CVT and the target permissible speed satisfying the target gear shifting condition; and a control module, configured to determine the final gear ratio of the CVT using the simulated speed ratio of the pulleys of the CVT corresponding to the target virtual gear, control the working oil pressure of the input pulley and output pulley of the CVT to maintain a target lock-up state according to the final gear ratio, and adjust the engine output torque of the target vehicle based on the torque control command issued by the transmission controller of the target vehicle to obtain an engine speed that meets a preset safety state, so as to control the overshoot of the CVT transmission speed.

[0011] Optionally, in one embodiment of this application, the first determining module includes: a generating unit, configured to generate a shift speed map of the CVT based on multiple accelerator pedal opening parameters and vehicle speed parameters; and a first determining unit, configured to determine the target permissible speed of the continuously variable transmission (CVT) based on the shift speed map, using the actual accelerator pedal opening and the actual vehicle speed.

[0012] Optionally, in one embodiment of this application, the second determining module includes: a calculation unit, configured to calculate the speed difference based on the current speed of the CVT and the target allowable speed; and a second determining unit, configured to determine that the target gear shifting condition is met when the speed difference is detected to be greater than or equal to a preset threshold, and to determine the target virtual gear of the CVT by matching the actual vehicle speed with a pre-set CVT virtual gear table.

[0013] Optionally, in one embodiment of this application, the control module includes: a third determining unit, configured to determine the target locking oil pressure corresponding to the input pulley and the output pulley based on the final speed ratio; and a control unit, configured to allocate the corresponding target locking oil pressure to the input pulley and the output pulley, so that the working oil pressure of the input pulley and the output pulley remains in the target locking state.

[0014] Optionally, in one embodiment of this application, the device further includes: a detection module, used to detect that after the overshoot of the CVT transmission speed is controlled, the engine speed of the target vehicle is adjusted to a preset safe speed range, and then the working oil pressure of the input pulley and the output pulley is released from the locked state to restore the continuously variable transmission adjustment of the CVT.

[0015] A third aspect of this application provides a vehicle, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the CVT transmission speed overshoot control method as described in the above embodiments.

[0016] A fourth aspect of this application provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described CVT transmission speed overshoot control method.

[0017] A fifth aspect of this application provides a computer program product, including a computer program that, when executed, is used to implement the CVT transmission speed overshoot control method described above.

[0018] This embodiment of the application can determine the target permissible speed of the CVT based on the actual throttle opening and vehicle speed when the vehicle is at risk of speed overshoot. Once the difference between the current speed and the target permissible speed reaches the shift threshold, a target virtual gear is selected based on the actual vehicle speed. The final gear ratio is calculated based on the simulated speed ratio of the pulleys in that gear, and the hydraulic lock-up ratio of the driving and driven pulleys is controlled accordingly. Simultaneously, the transmission controller sends commands to adjust the engine output torque, constraining the speed to a safe range, thus suppressing CVT speed overshoot and effectively improving the vehicle's power experience and NVH performance. This solves the problems in related technologies that easily lead to engine overspeeding, reduced power output, inability to guarantee vehicle acceleration stability under full load conditions, and decreased vehicle power experience and NVH performance.

[0019] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0020] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a flowchart of a CVT transmission speed overshoot control method according to an embodiment of this application; Figure 2 This is a structural diagram of a CVT transmission according to a specific embodiment of this application; Figure 3 This is a schematic diagram of the CVT transmission speed overshoot control principle according to a specific embodiment of this application; Figure 4 This is a schematic diagram of the engine power and torque curve of a specific embodiment of this application; Figure 5 This is a schematic diagram of a CVT transmission speed overshoot control device according to an embodiment of this application; Figure 6 This is a structural schematic diagram of a vehicle provided according to an embodiment of this application. Detailed Implementation

[0021] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0022] The following description, with reference to the accompanying drawings, outlines a CVT transmission speed overshoot control method, apparatus, vehicle, and storage medium according to embodiments of this application. Addressing the issues mentioned in the background section regarding the potential for engine overspeeding, reduced power output, and inability to guarantee vehicle acceleration stability under full load conditions, thus lowering vehicle power experience and NVH performance, this application provides a CVT transmission speed overshoot control method. In this method, when a vehicle experiences speed overshoot risk, a target permissible CVT speed is determined based on the actual throttle opening and vehicle speed. Once the difference between the current speed and the target permissible speed reaches a shift threshold, a target virtual gear is selected based on the actual vehicle speed. The final gear ratio is calculated using the simulated pulley speed ratio of that gear, and the hydraulic lock-up ratio of the driving and driven pulleys is controlled accordingly. Simultaneously, the transmission controller sends commands to adjust the engine output torque, constraining the speed to a safe range, thereby suppressing CVT speed overshoot and effectively improving vehicle power experience and NVH performance. This solves the problems in the related technologies, such as engine overspeeding, reduced power output, inability to guarantee vehicle acceleration stability under full load conditions, and lower vehicle power experience and NVH performance.

[0023] Specifically, Figure 1 This is a flowchart illustrating a CVT transmission speed overshoot control method provided in an embodiment of this application.

[0024] like Figure 1 As shown, the CVT transmission speed overshoot control method includes the following steps: In step S101, when the target vehicle is in a risky condition of transmission speed overshoot, the target permissible speed of the continuously variable transmission (CVT) of the target vehicle is determined based on the actual accelerator pedal opening and the actual vehicle speed.

[0025] In this embodiment, the transmission speed overshoot risk condition is the risk that the engine speed will exceed the limit when the vehicle accelerates rapidly at full throttle, due to the lag in hydraulic regulation.

[0026] It is understood that, in this embodiment of the application, after the vehicle enters a high-throttle rapid acceleration risk condition, the real-time accelerator pedal opening and vehicle speed are collected, and the pre-stored shift MAP is retrieved for lookup table calculation in the following steps to determine the target allowable speed corresponding to the CVT under the current condition. Thus, this embodiment of the application can accurately define the safe upper limit of the speed and improve the accuracy of condition identification and speed setting.

[0027] In one embodiment of this application, determining the target permissible speed of the continuously variable transmission (CVT) of the target vehicle based on the actual accelerator pedal opening and actual vehicle speed includes: generating a shift speed map table of the CVT based on multiple accelerator pedal opening parameters and vehicle speed parameters; and determining the target permissible speed of the CVT based on the shift speed map table using the actual accelerator pedal opening and actual vehicle speed.

[0028] In actual implementation, this embodiment can pre-collect multiple sets of different accelerator pedal opening parameters and corresponding vehicle speed parameters across the entire operating range. Combined with vehicle power calibration data, a CVT-specific shift speed map is generated. This map uses accelerator pedal opening as the horizontal index and vehicle speed as the vertical index, with the corresponding target speed pre-stored at the intersection of each index. During vehicle operation, the actual accelerator pedal opening and actual vehicle speed are collected in real time. By matching the index position, the corresponding calibration value in the shift speed map is retrieved to determine the target allowable speed of the CVT under the current operating condition. Thus, through the above-mentioned table lookup calibration method, rapid and accurate matching of the target allowable speed under different driving conditions can be achieved, improving the real-time performance of the target speed value and the accuracy of operating condition adaptation.

[0029] Table 1 is a shift point speed map, where the X-axis represents pedal opening, the Y-axis represents vehicle speed, and the center axis represents the shift point engine speed. See Table 1 for details: Table 1

[0030] For example, embodiments of this application can be implemented using... Figure 2 The CVT transmission structure is described using the example of a CVT transmission. The CVT transmission includes a hydraulic torque converter 1, an input shaft 2, an input pulley (driving pulley) assembly 3, an output shaft 4, an output pulley (driven pulley) assembly 5, a steel belt 6, a pulley transmission gear 7, and a speed reducer assembly 8.

[0031] The actual speed ratio is the ratio of the input pulley speed to the output pulley speed in the pulley system (3 to 5). The oil pressure is calculated and adjusted in real time according to the input torque TCU of the gearbox. The target speed ratio is calculated based on the shift speed map table in Table 1. Combination Figure 2 and Figure 3 As shown, with the increase of engine speed, during the 0km / h to 100km / h acceleration test, under full speed and full load conditions, when the engine speed reaches the shift point in Table 1, the larger oil pressure applied by the transmission hydraulic control system to the input pulley 3 and output pulley 5 increases the difficulty of gear shifting, causing a small deviation in the gear ratio during shifting. This results in the actual gear ratio deviating from the target gear ratio, leading to a higher input shaft 2 speed. Since the input shaft 2 is directly connected to the engine through the hydraulic torque converter 1, this will cause the engine speed to exceed the shift point speed. Figure 4 The engine power-torque curve is derived from... Figure 4 It is known that when the engine torque increases to a certain extent, the engine torque gradually decreases as the engine speed increases, resulting in a decline in acceleration performance. Therefore, in the embodiments of this application, a simulated shifting function can be developed through the TCU (Transmission Control Unit) in the following steps. The fixed simulated speed ratio corresponding to the virtual gear is matched according to the vehicle speed, the working oil pressure of the input pulley and output pulley is locked, and the CVT transmission speed ratio is fixed, thereby improving the engine speed overshoot problem caused by hydraulic speed regulation lag.

[0032] In step S102, in response to the speed difference between the current speed of the CVT and the target allowable speed satisfying the target gear shifting condition, the target virtual gear of the CVT is determined using the actual vehicle speed.

[0033] In this embodiment of the application, the target gear shifting condition is the condition that the current speed exceeds a certain threshold of the target allowable speed.

[0034] It is understood that the embodiments of this application can collect the current actual speed of the CVT input shaft in real time and perform a difference calculation with it and the target allowable speed in the above steps. When the calculated speed difference is greater than a certain threshold, for example, if the preset safety threshold is set to 300 r / min, and the target allowable speed under the current operating condition is found to be 4200 r / min according to the table, and the current speed of the input shaft is collected in real time to reach 4520 r / min, the speed difference between the two is 320 r / min > 300 r / min, which meets the threshold requirement. The system determines that the gear shifting condition is met and enters the target virtual gear matching process. It determines that the target gear shifting condition is met, retrieves the simulated speed ratio table corresponding to the pre-stored virtual gear, and performs a table lookup index based on the actual vehicle speed collected in real time to match the CVT target virtual gear corresponding to the current operating condition. This can improve the reliability and control timeliness of gear switching under overshoot conditions.

[0035] Table 2 is the simulated speed ratio table, as detailed below: Table 2

[0036] Specifically, this application embodiment can simulate the fixed gears of a traditional geared transmission in a continuously variable transmission (CVT) or other transmission without fixed gears through an electronic control unit (TCU) and software algorithms. The CVT transmission itself achieves continuous, stepless changes in the transmission ratio through conical pulleys and a steel belt. The simulated shifting function does not physically add gears, but rather, through TCU control, divides the continuous transmission ratio range into several preset intervals (e.g., this application sets 9 gear intervals), each interval corresponding to a "virtual gear." When the vehicle speed and throttle opening meet the shifting requirements, the ECU will issue a command to the transmission to lock the transmission ratio or quickly jump to the target interval.

[0037] In one embodiment of this application, determining the target virtual gear of the CVT using the actual vehicle speed includes: calculating the speed difference between the current speed of the CVT and the target allowable speed; when the speed difference is detected to be greater than or equal to a preset threshold, determining that the target gear shifting condition is met, and using the actual vehicle speed to match a pre-set CVT virtual gear table to determine the target virtual gear of the CVT.

[0038] As one possible implementation method, this application embodiment can collect the current operating speed of the CVT input shaft in real time, retrieve the target allowable speed obtained from the previous calibration step, perform a difference calculation on the two sets of speed data to obtain the real-time speed deviation value; continuously monitor the calculation results, and when the speed difference is detected to be greater than or equal to the system overshoot judgment threshold, it is determined that the current operating condition meets the target gear shifting condition; subsequently, the real-time actual vehicle speed is collected, and the vehicle speed is used as the lookup table index parameter to retrieve the pre-calibrated CVT virtual gear table, and the corresponding gear parameter is found through index matching to finally determine the target virtual gear of the CVT under the current operating condition. For example, the vehicle speed range corresponding to the 9 gears can be: 1st gear: 0-25km / h, 2nd gear: 25-50km / h, 3rd gear: 50-75km / h, 4th gear: 75-100km / h, 5th gear: 100-125km / h, 6th gear: 125-150km / h, 7th gear: 150-175km / h, 8th gear: 9th gear, 1st gear: 100-125km / h, 1st gear: 125-150km / h, 1st gear: 150-175km / h, 8th gear: 100-125km / h, 9th ... Gear 1: 175-200 km / h, Gear 9: 200-225 km / h. Assuming the gear shift condition is triggered, the actual vehicle speed is 68 km / h, falling within the 50-75 km / h range. The target virtual gear (Gear 3) is matched, and its fixed simulated speed ratio is retrieved. This allows for precise control of the virtual gear activation timing based on the engine speed deviation threshold. Combined with vehicle speed lookup table selection, this improves the accuracy of target virtual gear selection under overshoot conditions.

[0039] In step S103, the final speed ratio of the CVT is determined by using the simulated speed ratio of the pulleys of the CVT corresponding to the target virtual gear. Based on the final speed ratio, the working oil pressure of the input pulley and the output pulley of the CVT is controlled to maintain the target lock-up state. Based on the torque control command issued by the transmission controller of the target vehicle, the engine output torque of the target vehicle is adjusted to obtain the engine speed that meets the preset safety state, so as to control the overshoot of the CVT transmission speed.

[0040] In this embodiment, the preset safety state is when the actual engine speed drops and stabilizes within a reasonable range near the target allowable speed, the speed overshoot phenomenon is eliminated, and the speed no longer fluctuates excessively high.

[0041] It is understood that the embodiments of this application can retrieve the simulated speed ratio of the pulley corresponding to the determined target virtual gear, and determine the final speed ratio of the CVT based on the simulated speed ratio of the pulley; the TCU calculates the required oil pressure values ​​of the input and output pulleys based on the final speed ratio, and precisely controls the clamping oil pressure of the input pulley and output pulley, so that the distance between the driving and driven pulleys is fixed and the working radius of the steel belt no longer changes, thereby achieving speed ratio lock-up; at the same time, the transmission controller sends a torque control command to the engine electronic control unit, and reduces the engine output torque as needed, limiting the maximum engine speed to not exceed the shift point speed, preventing overspeed, and constraining the engine to return to the safe speed range, thereby suppressing the problem of CVT input shaft and engine speed overshoot under rapid acceleration conditions; for example, Figure 2 As shown in the embodiment of this application, a simulated speed ratio table similar to Table 2 can be developed using TCU software. The simulated speed ratio function is integrated into the TCU software to control the rotational speeds of the input pulley 3 and the output pulley 5. When the shift line speed is reached, the TCU issues a torque reduction request. The engine ECU responds to the TCU's torque reduction request, reducing the engine speed and limiting the maximum engine speed to no more than the shift point speed to prevent overspeeding. Thus, by coordinating the locking pulley hydraulic pressure with engine torque adjustment, the lag defect of hydraulic dynamic speed regulation is avoided, and the engine speed overshoot suppression effect is improved.

[0042] In one embodiment of this application, controlling the working oil pressure of the input pulley and output pulley of the CVT to maintain a target lock-up state according to the final speed ratio includes: determining the target lock-up oil pressure corresponding to the input pulley and output pulley according to the final speed ratio; and allocating the corresponding target lock-up oil pressure to the input pulley and output pulley so that the working oil pressure of the input pulley and output pulley maintains the target lock-up state.

[0043] In some embodiments, this application embodiment can determine the target lock-up oil pressure required for the input pulley and output pulley based on the corresponding parameter relationship between the simulated speed ratio of each virtual gear and the pulley lock-up oil pressure, according to the final speed ratio. The TCU outputs a control signal to the transmission hydraulic valve body, which delivers corresponding pressure oil to the input pulley cylinder and the output pulley cylinder respectively, accurately distributing the target lock-up oil pressure on both sides, fixing the axial position of the cone disc and the wrapping radius of the steel belt so that the input pulley and output pulley maintain the target lock-up state for a long time, and the CVT transmission speed ratio no longer deviates with hydraulic fluctuations. For example, after the vehicle triggers gear shifting and matches the M3 gear, it can be found from the table that the simulated speed ratio of the M3 pulley is 1.15, the final reduction ratio is fixed at 6.1, and the calculated final speed ratio is 7.015. Based on this final speed ratio, the preset calibration parameters are retrieved to determine the target lock-up oil pressure corresponding to the input and output pulleys. The hydraulic system continuously outputs the corresponding oil pressure to lock the pulleys, and the CVT transmission speed ratio is fixed at 7.015 and no longer changes dynamically. This allows for pulley locking by using a speed ratio calibration matching method based on hydraulic pressure, thereby improving the matching accuracy of locking hydraulic pressure and the stability of speed ratio fixation.

[0044] Optionally, in one embodiment of this application, after controlling the overshoot of the CVT transmission speed, the method further includes: after detecting that the engine speed of the target vehicle has been adjusted to a preset safe speed range, removing the working oil pressure of the input pulley and output pulley from the locked state, and restoring the CVT's continuously variable transmission adjustment.

[0045] In some embodiments, this application can continuously collect the actual engine speed in real time via TCU and compare it with the safe speed range for monitoring. When the engine speed is detected to drop and stabilize within the safe speed range, eliminating the speed overshoot risk, the control hydraulic valve group gradually removes the locking oil pressure of the input pulley and output pulley, releases the position lock of the driving and driven pulley cones, and the steel belt can readjust its working winding radius according to the oil pressure change. The CVT exits the fixed speed ratio mode and restores the original conventional control logic of continuously variable transmission based on the shift speed map to dynamically adjust the oil pressure. For example, if the M3 gear and final speed ratio of 7.015 were locked in the overshoot condition, after the engine speed drops from 4520 r / min to the target allowable speed of 4200 r / min and stabilizes, the hydraulic pressure is released to release the lock, and the transmission returns to continuously variable transmission. This allows for timely unlocking and restoration of continuously variable control after the overshoot risk is eliminated, balancing the advantages of overshoot prevention in extreme conditions and continuously variable transmission in normal driving, thus improving the overall driving smoothness of the vehicle.

[0046] The CVT transmission speed overshoot control method proposed in this application can determine the target allowable CVT speed based on the actual throttle opening and vehicle speed when the vehicle is at risk of speed overshoot. Once the difference between the current speed and the target allowable speed reaches the shift threshold, a target virtual gear is selected based on the actual vehicle speed. The final gear ratio is calculated using the simulated pulley speed ratio of that gear, and the hydraulic lock-up ratio of the driving and driven pulleys is controlled accordingly. Simultaneously, the transmission controller sends commands to adjust the engine output torque, constraining the speed to a safe range, thus suppressing CVT speed overshoot and effectively improving vehicle power experience and NVH performance. This solves the problems in related technologies that easily cause engine overspeeding, power output decline, inability to guarantee vehicle acceleration stability under full load conditions, and reduced vehicle power experience and NVH performance.

[0047] Next, with reference to the accompanying drawings, a CVT transmission speed overshoot control device according to an embodiment of this application is described.

[0048] Figure 5 This is a block diagram of the CVT transmission speed overshoot control device according to an embodiment of this application.

[0049] like Figure 5 As shown, the CVT transmission speed overshoot control device 10 includes: a first determining module 100, a second determining module 200, and a control module 300.

[0050] Specifically, the first determining module 100 is used to determine the target permissible speed of the continuously variable transmission (CVT) of the target vehicle based on the actual accelerator pedal opening and the actual vehicle speed when the target vehicle is in a risky condition of transmission speed overshoot.

[0051] The second determining module 200 is used to determine the target virtual gear of the CVT based on the actual vehicle speed, in response to the speed difference between the current speed of the CVT and the target allowable speed satisfying the target gear shifting condition.

[0052] The control module 300 is used to determine the final speed ratio of the CVT by simulating the speed ratio of the pulleys of the CVT corresponding to the target virtual gear. Based on the final speed ratio, it controls the working oil pressure of the input pulley and the output pulley of the CVT to maintain the target lock-up state. Based on the torque control command issued by the transmission controller of the target vehicle, it adjusts the engine output torque of the target vehicle to obtain the engine speed that meets the preset safety state, so as to control the overshoot of the CVT transmission speed.

[0053] Optionally, in one embodiment of this application, the first determining module 100 includes a generating unit and a first determining unit.

[0054] The generation unit is used to generate a CVT shift speed map based on multiple accelerator pedal opening parameters and vehicle speed parameters.

[0055] The first determining unit is used to determine the target permissible speed of the continuously variable transmission (CVT) based on the shift speed map table, using the actual accelerator pedal opening and the actual vehicle speed.

[0056] Optionally, in one embodiment of this application, the second determining module 200 includes: a calculation unit and a second determining unit.

[0057] The calculation unit is used to calculate the speed difference based on the current speed of the CVT and the target allowable speed.

[0058] The second determining unit is used to determine that the target gear shifting condition is met when the detected speed difference is greater than or equal to a preset threshold, and to determine the target virtual gear of the CVT by matching the actual vehicle speed with a pre-set CVT virtual gear table.

[0059] Optionally, in one embodiment of this application, the control module 300 includes a third determining unit and a control unit.

[0060] The third determining unit is used to determine the target lock-up oil pressure corresponding to the input pulley and the output pulley based on the final speed ratio.

[0061] The control unit is used to distribute the corresponding target locking oil pressure to the input pulley and the output pulley, so that the working oil pressure of the input pulley and the output pulley remains in the target locking state.

[0062] Optionally, in one embodiment of this application, the apparatus 10 of this application embodiment further includes a detection module.

[0063] The detection module is used to control the overshoot of the CVT transmission speed, detect when the engine speed of the target vehicle is adjusted to the preset safe speed range, and then release the working oil pressure of the input pulley and output pulley from the locked state to restore the CVT's continuously variable transmission adjustment.

[0064] It should be noted that the foregoing explanation of the CVT transmission speed overshoot control method embodiment also applies to the CVT transmission speed overshoot control device of this embodiment, and will not be repeated here.

[0065] The CVT transmission speed overshoot control device proposed in this application can determine the target allowable CVT speed based on the actual throttle opening and vehicle speed when the vehicle is at risk of speed overshoot. Once the difference between the current speed and the target allowable speed reaches the shift threshold, a target virtual gear is selected based on the actual vehicle speed. The final gear ratio is calculated based on the simulated speed ratio of the pulleys in that gear, and the hydraulic lock-up ratio of the driving and driven pulleys is controlled accordingly. Simultaneously, the transmission controller sends commands to adjust the engine output torque, constraining the speed to a safe range, thus suppressing CVT speed overshoot and effectively improving vehicle power experience and NVH performance. This solves the problems in related technologies that easily cause engine overspeeding, power output decline, inability to guarantee vehicle acceleration stability under full load conditions, and reduced vehicle power experience and NVH performance.

[0066] Figure 6 A schematic diagram of the structure of a vehicle provided in an embodiment of this application. The vehicle may include: The memory 601, the processor 602, and the computer program stored on the memory 601 and capable of running on the processor 602.

[0067] When the processor 602 executes the program, it implements the CVT transmission speed overshoot control method provided in the above embodiments.

[0068] Furthermore, the vehicle also includes: Communication interface 603 is used for communication between memory 601 and processor 602.

[0069] The memory 601 is used to store computer programs that can run on the processor 602.

[0070] The memory 601 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk storage device.

[0071] If the memory 601, processor 602, and communication interface 603 are implemented independently, then the communication interface 603, memory 601, and processor 602 can be interconnected via a bus to complete communication between them. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. The bus can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 6The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0072] Optionally, in a specific implementation, if the memory 601, processor 602, and communication interface 603 are integrated on a single chip, then the memory 601, processor 602, and communication interface 603 can communicate with each other through an internal interface.

[0073] The processor 602 may be a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this application.

[0074] This embodiment also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described CVT transmission speed overshoot control method.

[0075] This embodiment also provides a computer program product, including a computer program, which, when executed, is used to implement the CVT transmission speed overshoot control method described above.

[0076] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0077] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0078] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or N executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0079] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0080] It should be understood that the various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0081] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0082] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0083] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. A method for controlling speed overshoot in a CVT transmission, characterized in that, Includes the following steps: When the target vehicle is in a condition where the transmission speed is at risk of overshoot, the target permissible speed of the continuously variable transmission (CVT) of the target vehicle is determined based on the actual accelerator pedal opening and the actual vehicle speed. In response to the fact that the speed difference between the current speed of the CVT and the target allowable speed meets the target gear shifting conditions, the target virtual gear of the CVT is determined using the actual vehicle speed; The final speed ratio of the CVT is determined by using the simulated speed ratio of the pulleys corresponding to the target virtual gear. Based on the final speed ratio, the working oil pressure of the input pulley and output pulley of the CVT is controlled to maintain the target lock-up state. Based on the torque control command issued by the transmission controller of the target vehicle, the engine output torque of the target vehicle is adjusted to obtain the engine speed that meets the preset safety state, so as to control the overshoot of the CVT transmission speed.

2. The method according to claim 1, characterized in that, The step of determining the target permissible speed of the continuously variable transmission (CVT) of the target vehicle based on the actual accelerator pedal opening and actual vehicle speed includes: A shift speed map table for the CVT is generated based on multiple accelerator pedal opening parameters and vehicle speed parameters; Based on the shift speed map, the target permissible speed of the continuously variable transmission (CVT) is determined using the actual accelerator pedal opening and the actual vehicle speed.

3. The method according to claim 1, characterized in that, Determining the target virtual gear of the CVT using the actual vehicle speed includes: The speed difference is calculated based on the current speed of the CVT and the target allowable speed. When the speed difference is detected to be greater than or equal to a preset threshold, it is determined that the target gear shifting condition is met, and the target virtual gear of the CVT is determined by matching the actual vehicle speed with a pre-set CVT virtual gear table.

4. The method according to claim 1, characterized in that, The step of controlling the working hydraulic pressure of the input pulley and output pulley of the CVT to maintain the target lock-up state according to the final speed ratio includes: The target lock-up hydraulic pressure corresponding to the input pulley and the output pulley is determined based on the final speed ratio. The input pulley and output pulley are assigned corresponding target locking oil pressures so that the working oil pressures of the input pulley and output pulley remain in the target locking state.

5. The method according to claim 1, characterized in that, After controlling the overshoot of the CVT transmission speed, the method further includes: After the engine speed of the target vehicle is adjusted to the preset safe speed range, the working oil pressure of the input pulley and output pulley is released from the locked state, and the CVT's continuously variable transmission adjustment is restored.

6. A CVT transmission speed overshoot control device, characterized in that, include: The first determining module is used to determine the target permissible speed of the continuously variable transmission (CVT) of the target vehicle based on the actual accelerator pedal opening and the actual vehicle speed when the target vehicle is in a risky condition of transmission speed overshoot. The second determining module is used to determine the target virtual gear of the CVT in response to the speed difference between the current speed of the CVT and the target allowable speed satisfying the target gear shifting condition, using the actual vehicle speed. The control module is used to determine the final speed ratio of the CVT by using the simulated speed ratio of the pulleys of the CVT corresponding to the target virtual gear, control the working oil pressure of the input pulley and output pulley of the CVT to maintain the target lock-up state according to the final speed ratio, and adjust the engine output torque of the target vehicle based on the torque control command issued by the transmission controller of the target vehicle to obtain the engine speed that meets the preset safety state, so as to control the overshoot of the CVT transmission speed.

7. The apparatus according to claim 6, characterized in that, The first determining module includes: The generation unit is used to generate a shift speed map table of the CVT based on multiple accelerator pedal opening parameters and vehicle speed parameters; The first determining unit is used to determine the target permissible speed of the continuously variable transmission (CVT) based on the shift speed map table, using the actual accelerator pedal opening and the actual vehicle speed.

8. A vehicle, characterized in that, include: The system includes a memory, a processor, and a computer program stored in the memory and capable of running on the processor, wherein the processor executes the program to implement the CVT transmission speed overshoot control method as described in any one of claims 1-5.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, The program is executed by the processor to implement the CVT transmission speed overshoot control method as described in any one of claims 1-5.

10. A computer program product, comprising a computer program, characterized in that, The computer program is executed by a processor to implement the CVT transmission speed overshoot control method as described in any one of claims 1-5.

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