A control method and device for a continuously variable transmission

Abstract

This application discloses a control method and apparatus for a continuously variable transmission (CVT). The method includes: determining a base value for the current clamping force of the target vehicle based on the current road surface roughness level and the correspondence between the road surface roughness level and the base value of the clamping force of the steel belt; calculating the required value of the current clamping force of the target vehicle based on the current impact load of the target vehicle; then, obtaining the maximum value between the base value and the required value of the current clamping force; and finally, setting the current clamping force of the steel belt of the CVT of the target vehicle based on the maximum value of the current clamping force. This method can reduce the risk of steel belt slippage while lowering vehicle fuel consumption, improving vehicle economy and steel belt safety, and is beneficial for vehicle operation on complex road surfaces.

Description

Technical Field

[0001] This application relates to the field of vehicles, specifically to a control method and device for a continuously variable transmission (CVT). Background Technology

[0002] In the automotive field, traditional manual and automatic transmissions currently cannot achieve continuous changes in gear ratio, making it difficult to maintain the optimal match between the vehicle's drivetrain and engine. Continuously Variable Transmission (CVT), as a new type of power-shifting transmission, uses a drive belt and variable-diameter pulleys to transmit power, enabling continuous changes in gear ratio. This maintains the optimal match between the vehicle's drivetrain and engine, ensuring the engine always operates in its high-efficiency range and maximizing its potential.

[0003] Currently, the clamping force control method for the steel belt in continuously variable transmissions (CVTs) in vehicles works as follows: when the vehicle is traveling on different road surfaces, it generally operates with the clamping force set before protection is activated. If the road surface is identified as a severe condition, the clamping force is then increased according to a pre-set standard for severe conditions. However, this simple clamping force control method is difficult to adapt to complex road conditions, which can lead to higher fuel consumption or the risk of steel belt slippage, resulting in low vehicle economy and low steel belt safety. Summary of the Invention

[0004] This application provides a control method and device for a continuously variable transmission (CVT) that can adapt to complex road conditions, reduce vehicle fuel consumption, and prevent steel belt slippage, thereby improving vehicle economy and steel belt safety.

[0005] In view of this, the first aspect of the present application provides a control method for a continuously variable transmission (CVT), the method comprising:

[0006] Based on the current road surface roughness level of the target vehicle and the correspondence between the road surface roughness level of the target vehicle and the basic value of the clamping force of the steel belt, the current clamping force of the target vehicle is determined; wherein, the road surface roughness level is a set of multiple levels that represent the degree of road surface roughness when the vehicle is traveling, and the correspondence is obtained in advance by fitting the actual torque value transmitted by the steel belt when the vehicle is traveling on the road surface corresponding to different road surface roughness levels.

[0007] Based on the current impact load of the target vehicle, the required current clamping force of the target vehicle is calculated.

[0008] Obtain the maximum value of the current clamping force between the current base value and the current required value of the current clamping force;

[0009] Based on the maximum value of the current clamping force, the current clamping force of the steel belt of the continuously variable transmission of the target vehicle is set.

[0010] A second aspect of this application provides a control device for a continuously variable transmission (CVT), the device comprising:

[0011] The current clamping force base value calculation unit is used to determine the current clamping force base value of the target vehicle based on the current road surface bump level of the target vehicle and the correspondence between the road surface bump level of the target vehicle and the clamping force base value of the steel belt; wherein, the road surface bump level is a set of multiple preset levels representing the degree of road surface bumps when the vehicle is traveling, and the correspondence is pre-fitted based on the actual torque value transmitted by the steel belt when the vehicle is traveling on the road surface corresponding to different road surface bump levels.

[0012] The current clamping force required value calculation unit is used to calculate the current clamping force required value of the target vehicle based on the current impact load of the target vehicle;

[0013] The maximum value acquisition unit for current clamping force is used to acquire the maximum value of clamping force between the current basic value of clamping force and the current required value of clamping force.

[0014] The current clamping force setting unit is used to set the current clamping force of the steel belt of the continuously variable transmission of the target vehicle based on the maximum value of the current clamping force.

[0015] A third aspect of this application provides an electronic device, including:

[0016] Memory, used to store executable instructions;

[0017] The processor, when executing executable instructions stored in the memory, implements a continuously variable transmission (CVT) control method provided in the embodiments of this application.

[0018] A fourth aspect of this application provides a computer-readable medium storing executable instructions for implementing a continuously variable transmission (CVT) control method provided in this application when executed by a processor.

[0019] As can be seen from the above technical solutions, the embodiments of this application have the following advantages:

[0020] This application discloses a control method and apparatus for a continuously variable transmission (CVT). The method includes: determining a base value for the current clamping force of the target vehicle based on the current road surface roughness level of the target vehicle and the correspondence between the road surface roughness level and the base value of the clamping force of the steel belt. The road surface roughness level is a pre-set set of multiple levels representing the degree of road surface roughness when the vehicle is driving. The correspondence is pre-fitted based on the actual torque values ​​transmitted by the steel belt when driving on roads corresponding to multiple different road surface roughness levels. Since pre-setting multiple road surface roughness levels can cover a variety of road conditions as much as possible, the base value of the current clamping force determined based on the current road surface roughness level can be very close to the actual required clamping force value, thereby reducing the fuel consumption required by the vehicle due to providing excessive clamping force; calculating the required current clamping force value of the target vehicle based on the current impact load of the target vehicle; then, obtaining the maximum value between the base value of the current clamping force and the required current clamping force value; finally, setting the current clamping force of the steel belt of the CVT of the target vehicle based on the maximum value of the current clamping force value. Since the current clamping force, set according to the maximum value, meets the vehicle's actual clamping requirements, the risk of slippage due to insufficient clamping force is reduced. This method reduces the risk of steel belt slippage while improving fuel economy and steel belt safety, thus benefiting vehicle operation on complex road surfaces. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0022] Figure 1 The target speed ratio determination diagram of the continuously variable transmission (CVT) provided in the embodiments of this application;

[0023] Figure 2 The diagram illustrates the effect of the control method for continuously variable transmissions (CVTs) currently used in this application.

[0024] Figure 3 This is a working scenario diagram of a continuously variable transmission (CVT) provided in an embodiment of this application;

[0025] Figure 4 A flowchart illustrating a control method for a continuously variable transmission (CVT) provided in this application embodiment;

[0026] Figure 5 A flowchart illustrating another control method for a continuously variable transmission (CVT) provided in another embodiment of this application;

[0027] Figure 6 The diagram illustrates the effect of the control method for a continuously variable transmission (CVT) provided in the embodiments of this application.

[0028] Figure 7 This is a schematic diagram of a control device for a continuously variable transmission (CVT) provided in another embodiment of this application. Detailed Implementation

[0029] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0030] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0031] Before providing a further detailed description of the embodiments of this application, the nouns and terms involved in the embodiments of this application will be explained, and the nouns and terms involved in the embodiments of this application shall be interpreted as follows.

[0032] A continuously variable transmission (CVT) is a new type of power shift transmission that uses a steel belt and variable diameter primary and driven pulleys to transmit power, enabling continuous changes in the speed ratio and thus achieving optimal matching between the transmission system and engine operating conditions.

[0033] See Figure 1 , Figure 1The target gear ratio determination diagram for continuously variable transmissions (CVTs) provided in the embodiments of this application describes a current method for determining the target gear ratio of a CVT. This method involves first determining the current target engine speed based on the throttle opening and vehicle speed, and then calculating the current CVT target gear ratio based on the current target engine speed. This method ensures that the vehicle's engine operates in the optimal fuel economy zone, significantly reducing fuel consumption.

[0034] Currently, the clamping force control method for the steel belt in continuously variable transmissions (CVTs) used in vehicles involves the following: when the vehicle is traveling on different road surfaces, it generally operates with the clamping force set before protection is activated. If the road surface is identified as a severe condition, the clamping force is then increased according to a pre-set severe condition standard. The applicant has found that this simple clamping force control method is difficult to adapt to complex road conditions. Specifically, see [link to relevant documentation]. Figure 2 , Figure 2 The diagram illustrates the effect of the control method for the continuously variable transmission (CVT) currently used in this application. Area 201 shows the case where protection is not activated; area 203 shows the case where protection is activated under adverse operating conditions; area 202 shows the case where even slightly bumpy roads are identified as adverse operating conditions, where the target torque transmitted on the belt is significantly greater than the actual transmitted torque, resulting in redundant belt clamping force and high vehicle fuel consumption; area 204 shows the case where, under severely bumpy roads, the actual impact load is large, and the actual torque transmitted on the belt is significantly greater than the target transmitted torque, resulting in insufficient belt clamping force and a risk of belt slippage. In other words, the applicant found that the current control method for CVTs is difficult to adapt to complex road conditions. Protection can only be effectively activated when the pre-set adverse operating conditions precisely match the actual road conditions, resulting in high fuel consumption and the risk of belt slippage, leading to low vehicle economy and safety.

[0035] In view of this, this application provides a control method for a continuously variable transmission (CVT). The method includes: determining a current clamping force base value for the target vehicle based on the current road surface roughness level of the target vehicle and the correspondence between the road surface roughness level and the clamping force base value of the steel belt. The road surface roughness level is a pre-set set of multiple levels representing the degree of road surface roughness when the vehicle is driving. The correspondence is pre-fitted based on the actual torque values ​​transmitted by the steel belt when driving on roads corresponding to multiple different road surface roughness levels. Since pre-setting multiple road surface roughness levels can cover a variety of road conditions as much as possible, the current clamping force base value determined based on the current road surface roughness level can be very close to the actual required clamping force value, thereby reducing the fuel consumption required by the vehicle due to providing excessive clamping force; calculating the required current clamping force value for the target vehicle based on the current impact load; then, obtaining the maximum value between the current clamping force base value and the current clamping force required value; finally, setting the current clamping force of the steel belt of the CVT of the target vehicle based on the maximum value of the current clamping force value. Since the current clamping force, set according to the maximum value, meets the vehicle's actual clamping requirements, the risk of slippage due to insufficient clamping force is reduced. This method reduces the risk of steel belt slippage while improving fuel economy and steel belt safety, thus benefiting vehicle operation on complex road surfaces.

[0036] To illustrate the control method of the continuously variable transmission (CVT) provided in the embodiments of this application, optionally, the embodiments of this application provide a working scenario of the CVT, such as... Figure 3 As shown, Figure 3 The continuously variable transmission (CVT) working scenario diagram provided in the embodiments of this application includes:

[0037] Engine 301, traction control system 302, clutch 303, drive pulley 304, driven pulley 305, drive cylinder 306, and driven cylinder 307.

[0038] An engine is a machine that converts other forms of energy into mechanical energy to power other devices.

[0039] The function of the traction control system (TC) is to ensure that the vehicle obtains optimal traction under various driving conditions.

[0040] A clutch (DR Clutch) is a common component in mechanical transmissions, allowing the transmission system to be separated or engaged at any time. Specifically, during vehicle operation, the driver can depress or release the clutch pedal as needed to temporarily separate and gradually engage the engine and transmission, cutting off or transmitting power from the engine to the transmission.

[0041] In a continuously variable transmission (CVT), the working diameters of the driving and driven pulleys are variable, allowing them to work together to achieve continuous changes in the transmission ratio.

[0042] The pressure value of the active cylinder can be determined based on the target speed ratio of the continuously variable transmission (CVT) and the oil pressure of the driven cylinder. The target speed ratio is calculated based on the engine speed. The active cylinder is used to ensure that the actual speed ratio of the CVT follows the target speed ratio, that is, the active cylinder is responsible for speed ratio control.

[0043] The driven cylinder determines its pressure based on the torque transmitted by the steel belt and the actual speed ratio, which can be used to ensure that the steel belt can safely transmit torque, that is, the driven cylinder is responsible for the clamping force.

[0044] The control method of the continuously variable transmission (CVT) provided in this application will be described below through method embodiments, such as... Figure 4 As shown, Figure 4 A flowchart illustrating a control method for a continuously variable transmission (CVT) provided in this application embodiment is shown. The control method for a CVT provided in this application embodiment includes the following steps:

[0045] 401. Determine the current clamping force base value of the target vehicle based on the current road surface roughness level of the target vehicle and the correspondence between the road surface roughness level of the target vehicle and the base value of the clamping force of the steel belt; wherein, the road surface roughness level is a set of multiple levels that represent the degree of road surface roughness when the vehicle is traveling, and the correspondence is obtained in advance by fitting the actual torque value transmitted by the steel belt when the vehicle is traveling on the road surface corresponding to different road surface roughness levels.

[0046] Specifically, based on the target vehicle's current road surface roughness level and the correspondence between the target vehicle's road surface roughness level and the base value of the steel belt clamping force, the base value of the target vehicle's current clamping force can be determined. The road surface roughness level is a pre-set set of multiple levels representing the degree of road surface roughness experienced by the vehicle. Multiple levels can cover various road conditions; the more levels, the closer the current road surface roughness level is to the actual road surface roughness. The number of levels can be set according to the requirements of the administrator and is not limited here. Meanwhile, since the actual clamping force required by the steel belt can be determined by the actual torque value transmitted by the steel belt, this correspondence can be pre-fitted based on the actual torque value transmitted by the steel belt when the vehicle travels on roads corresponding to different road surface roughness levels. The fitting method can be either conducting experiments on the target vehicle under different road surface conditions or simulating the target vehicle and different road surface conditions.

[0047] By pre-setting multiple road bump levels, when the current clamping force base value is less than the actual clamping force required by the steel belt, the clamping force redundancy of the steel belt is reduced, the pressure of the steel belt system is reduced, and thus the fuel consumption required by the vehicle due to providing excessive clamping force is reduced, thereby improving fuel economy.

[0048] Optionally, the current road surface roughness level can be determined by the target vehicle's current torque, or by obtaining the vehicle's current vertical acceleration through the vehicle's suspension system.

[0049] Optionally, the current road surface bump level can be obtained in the following ways: Figure 5 As shown, Figure 5 A flowchart of another control method for a continuously variable transmission (CVT) provided in another embodiment of this application includes:

[0050] 501. Obtain and save the left drive wheel speed change rate and the right drive wheel speed change rate of the target vehicle in the current collection period; calculate the average wheel speed change rate of the target vehicle's drive wheels in the current collection period based on the average of the left drive wheel speed change rate and the right drive wheel speed change rate.

[0051] 502. Perform rolling average filtering on the left drive wheel speed change rate, right drive wheel speed change rate, and average drive wheel speed change rate within the current acquisition period to obtain the average left wheel speed change rate, the average right wheel speed change rate, and the average average wheel speed change rate. The rolling average filtering is performed by calculating the corresponding rolling arithmetic average based on the values ​​within the current acquisition period and the values ​​within at least one historical acquisition period.

[0052] Specifically, during vehicle operation, the wheel speed change rate of the left and right drive wheels can be obtained according to the data collection period. In order to ensure the reliability of the current road surface bump level determined based on the wheel speed change rate of the left and right drive wheels during actual vehicle operation, a rolling average filtering process can be performed on the obtained wheel speed change rate of the left and right drive wheels and the average wheel speed change rate to obtain the corresponding average value and determine the current road surface bump level. The rolling average filtering process is a method of calculating the arithmetic average of the values ​​obtained in the current data collection period and the values ​​obtained in at least one historical data collection period. The average wheel speed change rate obtained by performing rolling average filtering on the wheel speed change rate in the current data collection period can more reliably reflect the current road surface bump level and reduce the deviation of the values ​​caused by randomness.

[0053] The data acquisition period can be preset according to the user's requirements. Provided the machine can handle it, a shorter acquisition period will better reflect the vehicle's current driving status based on the acquired rate of change of drive wheel speed. For example, the acquisition period can be set to 10 milliseconds. The number of historical acquisition periods can also be preset according to the user's requirements; for example, two historical acquisition periods can be set.

[0054] 503. Obtain the maximum value of the wheel speed change rate among the average left wheel speed change rate, the average right wheel speed change rate, and the average wheel speed change rate;

[0055] 504. Based on the maximum value of the wheel speed change rate and the wheel speed change rate ranges corresponding to multiple road surface bump levels, determine the target wheel speed change rate range and determine the road surface bump level corresponding to the target wheel speed change rate range as the current road surface bump level.

[0056] It should be noted that obtaining the maximum value of the wheel speed change rate and determining the current road surface roughness level based on this value is to ensure that the current clamping force baseline value determined based on the current road surface roughness level can meet the actual clamping force required by the vehicle. Since subsequent steps require comparing the current clamping force baseline value with the current clamping force required value, if the current clamping force baseline value is too small, the current clamping force maximum value may be frequently determined as the current clamping force required value. The current clamping force required value reflects the actual clamping force required based on the current impact load, meaning that the current clamping force required value is a fluctuating value. This will cause the current clamping force of the steel belt to fluctuate frequently, thus affecting the life of the steel belt.

[0057] Furthermore, determining the current road surface bump level by the wheel speed change rate has less lag and is more accurate than methods such as torque and vertical acceleration.

[0058] 402. Based on the current impact load of the target vehicle, calculate the required value of the current clamping force of the target vehicle.

[0059] Specifically, the required clamping force for the target vehicle can be calculated from the current impact load. Since the clamping force required by the vehicle's steel belt is used to ensure the safe transmission of torque, the actual torque transmitted by the steel belt will change due to the change in impact load on the vehicle when driving on different road surfaces. Therefore, the required clamping force reflects the actual clamping force required at present, which is calculated from the current impact load.

[0060] Optionally, the current impact load of the target vehicle can be calculated based on the current driven pulley speed, the current difference in speed between the front and rear wheels, and the current difference in speed between the left and right wheels.

[0061] Specifically, the current impact load can be calculated using the rate of change of the current driven pulley speed, the rate of change of the current front and rear wheel speeds, and the rate of change of the current left and right wheel speeds. Since the bottom of a car is a surface, not a point, the current impact load calculated using these parameters can fully reflect the impact load on the surface of the vehicle's bottom, thus improving the accuracy of the current impact load.

[0062] Optionally, the current impact load can be obtained in the following ways:

[0063] The current speed of the drive pulley can be obtained using the following formula.

[0064]

[0065] Where ω1 is the current speed of the driving pulley, ω sec Δv is the current speed of the driven pulley. FR The difference in rotational speed between the front and rear wheels, Δv LR i represents the current difference in rotational speed between the left and right wheels. act For the steel belt pulley speed ratio, i0 is the main reducer pulley speed ratio, and r is the speed ratio of the main reducer pulley. wheel The radius of the wheel;

[0066] The current impact load is obtained using the following formula.

[0067]

[0068] Among them, T ofst Let k be the impact load. 2 It is the square of the ratio of the rate of change of the generator wheel speed to the rate of change of the turbine wheel speed. J is the square of the clutch speed ratio. eng For engine inertia, J lmpeller J is the pump impeller inertia. turb J is the turbine inertia. clch J is the inertia of the clutch driving end. planet J is the moment of inertia of the clutch driven end. pri ω1 is the moment of inertia of the active pulley, and ω1 is the current speed of the active pulley.

[0069] Specifically, the current driving pulley speed is first calculated based on the current driven pulley speed change rate, the current front and rear wheel speed change rate, and the current left and right wheel speed change rate. Among these, the current driven pulley speed, the current front and rear wheel speed difference, and the current left and right wheel speed difference need to be obtained in real time, while the steel belt pulley speed ratio, the main reducer wheel speed ratio, and the wheel radius can be measured in advance.

[0070] The current impact load is then calculated based on the current speed of the drive pulley. The square of the ratio of the generator pulley speed change rate to the turbine pulley speed change rate, the square of the clutch speed ratio, the engine inertia, pump wheel inertia, turbine inertia, clutch drive end inertia, clutch driven end inertia, and drive pulley inertia can all be measured in advance.

[0071] It should be noted that a vehicle is usually not subjected to impact loads at a single point during operation. The current driving pulley speed, calculated using the current driven pulley speed change rate, the current front and rear wheel speed change rate, and the current left and right wheel speed change rate, can fully reflect the impact load on the vehicle's underside. For example, when the road surface conditions on the left side of the vehicle differ from those on the right side, the current left and right wheel speed change rate will change accordingly. That is, the current left and right wheel speed change rate can reflect the impact load on the left and right sides of the vehicle in real time. Similarly, the current front and rear wheel speed change rate can reflect the impact load on the front and rear of the vehicle in real time. The driven pulley speed change rate can reflect the overall impact load on the vehicle.

[0072] The current driving pulley speed is obtained by comparing the calculated values ​​of the current driven pulley speed change rate, the current front and rear wheel speed change rate, and the current left and right wheel speed change rate, and taking the larger value. The current impact load is calculated using the current driving pulley speed to ensure that the current clamping force required by the calculated impact load is not less than the actual clamping force required by the steel belt, thereby reducing the risk of the vehicle's steel belt slipping due to insufficient clamping force.

[0073] In summary, the above method can accurately obtain the current impact load during vehicle operation, and thus accurately obtain the required current clamping force of the vehicle's steel belt, providing a theoretical basis for ensuring that the current clamping force of the vehicle's steel belt meets the actual clamping force required by the steel belt.

[0074] 403. Obtain the maximum value of the current clamping force between the current clamping force base value and the current clamping force required value.

[0075] 404. Based on the current maximum clamping force value, set the current clamping force of the steel belt of the continuously variable transmission of the target vehicle.

[0076] It should be noted that the required current clamping force is calculated based on the current impact load and reflects the actual clamping force needed by the steel strip. By taking the larger of the baseline current clamping force and the required current clamping force as the current clamping force, the following can be achieved: when the baseline current clamping force is greater than the required current clamping force (i.e., under most road conditions), the current clamping force meets the actual clamping force required by the steel strip, reducing the risk of slippage, and also considering the road surface roughness level. Multiple clamping forces can reduce the redundancy of the steel belt clamping force, thereby reducing vehicle fuel consumption. Even when the required clamping force exceeds the baseline clamping force, i.e., under extremely rough road conditions, the required clamping force calculated based on the current impact load can still meet the actual clamping force needed by the steel belt, reducing the risk of slippage. However, since the required clamping force is typically a fluctuating value, consistently using the required clamping force as the current clamping force would result in a fluctuating clamping force, reducing the lifespan of the steel belt. In summary, this embodiment of the application, while reducing vehicle fuel consumption, can achieve clamping force protection for the steel belt under different road conditions, preventing slippage and ensuring the safety of the vehicle's steel belt.

[0077] Optionally, the pressure values ​​of the drive pulley and driven pulley of the continuously variable transmission (CVT) of the target vehicle can be set according to the current clamping force of the steel belt.

[0078] Specifically, a continuously variable transmission (CVT) includes a driving cylinder and a driven cylinder. The driving cylinder can determine its pressure value based on the target speed ratio of the CVT and the oil pressure of the driven cylinder. The driving cylinder can be used to ensure that the actual speed ratio of the CVT follows the target speed ratio. In other words, the driving cylinder is responsible for speed ratio control, and the pressure value of the driving cylinder is the pressure value of the driving wheel.

[0079] The driven cylinder determines its pressure based on the torque transmitted by the steel belt and the actual speed ratio. It can be used to ensure that the steel belt can safely transmit torque. That is, the driven cylinder is responsible for the clamping force, and the pressure value of the driven cylinder is the pressure value of the driven wheel.

[0080] The required pressure values ​​for the driving and driven pulleys can be determined by the current clamping force of the steel belt.

[0081] Optionally, when the current road surface bump level indicates no bumps, the pressure values ​​of the driving and driven wheels can be maintained until the end of the delay period; where the delay period is a preset safety period. The pressure values ​​of the driving and driven wheels are then reduced according to the rate of pressure decrease.

[0082] Specifically, when the current road surface roughness level indicates no roughness, the current clamping force needs to be reduced from the historical current clamping force to the baseline clamping force value corresponding to a roughness-free road surface. To prevent clamping force redundancy, this baseline clamping force value is obviously too small. If an additional impact occurs on the road surface at this time, it may cause the vehicle's steel belt to slip, reducing the safety of the vehicle's steel belt. By maintaining the pressure values ​​of the driving and driven pulleys until the end of the delay period, and reducing the pressure values ​​of the driving and driven pulleys according to the rate of pressure decrease, the risk of slippage caused by additional impacts when the current road surface roughness level is no roughness can be reduced, thus providing a protective function.

[0083] Optionally, before setting the current clamping force of the steel belt of the continuously variable transmission (CVT) of the target vehicle based on the maximum value of the current clamping force, a preliminary current clamping force of the steel belt of the CVT of the target vehicle can be set based on the current base value of the clamping force.

[0084] Specifically, this application's embodiments calculate the current clamping force base value and the current clamping force required value. The current clamping force base value is determined based on the current road surface roughness level, which does not change frequently during vehicle operation. The current clamping force required value, however, is determined based on the current impact load, which typically fluctuates during vehicle operation. Therefore, the clamping force can be adjusted in advance based on the current clamping force base value, i.e., a pre-set current clamping force for the steel belt can be established. If the current clamping force base value is determined to be the maximum current clamping force value, i.e., the pre-set current clamping force is equivalent to the current clamping force, thus providing advance protection for the vehicle's steel belt. If the current clamping force required value is determined to be the maximum current clamping force value, i.e., the pre-set current clamping force differs from the current clamping force, the current clamping force is still set based on the maximum current clamping force value. This is equivalent to setting the current clamping force of the steel belt in two separate steps, also achieving advance protection for the vehicle's steel belt. In summary, by pre-setting the current clamping force of the continuously variable transmission (CVT) belt of the target vehicle based on the current clamping force baseline value, the steel belt of the vehicle can be protected in advance.

[0085] The continuously variable transmission (CVT) control method provided in this application can adapt to complex road conditions. Specifically, see [link to relevant documentation]. Figure 6 , Figure 6 The diagram shows the effect of the continuously variable transmission (CVT) control method provided in the embodiments of this application. Area 601 shows the situation where the protection is not activated when the target vehicle starts driving. Areas 602, 603 and 604 show that under different road conditions, the CVT control method provided in the embodiments of this application can achieve the target transmission torque of the steel belt to meet the actual transmission torque requirement, that is, the clamping force activation protection, and at this time there will be no large amount of clamping force redundancy.

[0086] In addition, area 605 shows that when the current road surface bump level of the target vehicle is displayed as no bumps, the pressure values ​​of the driving wheel and driven wheel are reduced according to the rate of pressure value decrease. This can reduce the risk of slippage caused by additional impacts when the current road surface bump level is no bumps, thus playing a protective role.

[0087] This application discloses a control method for a continuously variable transmission (CVT). The method includes: determining a base value for the current clamping force of the target vehicle based on the current road surface roughness level and the correspondence between the road surface roughness level and the base value of the clamping force of the steel belt. The road surface roughness level is a pre-set set of multiple levels representing the degree of road surface roughness when the vehicle is driving. The correspondence is pre-fitted based on the actual torque values ​​transmitted by the steel belt when driving on roads corresponding to multiple different road surface roughness levels. Since pre-setting multiple road surface roughness levels can cover a variety of road conditions as much as possible, the base value of the current clamping force determined based on the current road surface roughness level can be very close to the actual required clamping force value, thereby reducing the fuel consumption required by the vehicle due to providing excessive clamping force; calculating the required current clamping force value of the target vehicle based on the current impact load of the target vehicle; then, obtaining the maximum value between the base value of the current clamping force and the required current clamping force value; finally, setting the current clamping force of the steel belt of the CVT of the target vehicle based on the maximum value of the current clamping force value. Since the current clamping force, set according to the maximum value, meets the vehicle's actual clamping requirements, the risk of slippage due to insufficient clamping force is reduced. This method reduces the risk of steel belt slippage while improving fuel economy and steel belt safety, thus benefiting vehicle operation on complex road surfaces.

[0088] Another embodiment of this application provides a control device for a wireless transmission, such as... Figure 7 As shown, Figure 7 A schematic diagram of a control device for a continuously variable transmission (CVT) according to another embodiment of this application is provided. The device includes:

[0089] The current clamping force base value calculation unit 701 is used to determine the current clamping force base value of the target vehicle based on the current road surface bump level of the target vehicle and the correspondence between the road surface bump level of the target vehicle and the clamping force base value of the steel belt; wherein, the road surface bump level is a set of multiple pre-set levels representing the degree of road surface bumps when the vehicle is traveling, and the correspondence is pre-fitted based on the actual torque value transmitted by the steel belt when the vehicle is traveling on the road surface corresponding to different road surface bump levels.

[0090] The current clamping force required value calculation unit 702 is used to calculate the current clamping force required value of the target vehicle based on the current impact load of the target vehicle;

[0091] The maximum value acquisition unit 703 for current clamping force is used to acquire the maximum value of clamping force between the current basic value of clamping force and the current required value of clamping force.

[0092] The current clamping force setting unit 704 is used to set the current clamping force of the steel belt of the continuously variable transmission of the target vehicle based on the maximum value of the current clamping force.

[0093] Optionally, in another embodiment of the wireless transmission control device provided in this application, the following further includes:

[0094] The current road surface bumpiness level determination unit is used to acquire and save the left and right drive wheel speed change rates of the target vehicle in the current acquisition period; calculate the average wheel speed change rate of the target vehicle's drive wheels in the current acquisition period by averaging the left and right drive wheel speed change rates; perform rolling average filtering on the left, right, and average drive wheel speed change rates in the current acquisition period to obtain the average left wheel speed change rate, the average right wheel speed change rate, and the average wheel speed change rate; the rolling average filtering process calculates the corresponding rolling arithmetic average based on the values ​​in the current acquisition period and the values ​​in at least one historical acquisition period; obtain the maximum wheel speed change rate value among the average left wheel speed change rate, the average right wheel speed change rate, and the average wheel speed change rate; determine the target wheel speed change rate value range based on the maximum wheel speed change rate value and the wheel speed change rate value ranges corresponding to multiple road surface bumpiness levels, and determine the road surface bumpiness level corresponding to the target wheel speed change rate value range as the current road surface bumpiness level.

[0095] Optionally, in another embodiment of the wireless transmission control device provided in this application, the following further includes:

[0096] The first unit for calculating the current impact load is used to calculate the current impact load of the target vehicle based on the current driven pulley speed, the current difference in speed between the front and rear wheels, and the current difference in speed between the left and right wheels.

[0097] Optionally, in another embodiment of the wireless transmission control device provided in this application, the following further includes:

[0098] The second unit for calculating the current impact load is used to obtain the current speed of the driving pulley using the following formula.

[0099]

[0100] Where ω1 is the current speed of the driving pulley, ω sec Δv is the current speed of the driven pulley. FR The difference in rotational speed between the front and rear wheels, Δv LRi represents the current difference in rotational speed between the left and right wheels. act For the steel belt pulley speed ratio, i0 is the main reducer pulley speed ratio, and r is the speed ratio of the main reducer pulley. wheel The radius of the wheel;

[0101] The current impact load is obtained using the following formula.

[0102]

[0103] Among them, T ofst For impact load, k 2 It is the square of the ratio of the rate of change of the generator wheel speed to the rate of change of the turbine wheel speed. J is the square of the clutch speed ratio. eng For engine inertia, J lmpeller J is the pump impeller inertia. turb J is the turbine inertia. clch J is the inertia of the clutch driving end. planet J is the moment of inertia of the clutch driven end. pri ω1 is the moment of inertia of the active pulley, and ω1 is the current speed of the active pulley.

[0104] Optionally, in another embodiment of the wireless transmission control device provided in this application, the following further includes:

[0105] The driving and driven pulley pressure value determination unit is used to set the pressure values ​​of the driving pulley and driven pulley of the continuously variable transmission of the target vehicle based on the current clamping force of the steel belt.

[0106] Optionally, in another embodiment of the wireless transmission control device provided in this application, the following further includes:

[0107] The descent control unit is used to maintain the pressure values ​​of the driving wheel and the driven wheel until the end of the delay period when the current road surface bump level indicates no bumps; wherein the delay period is a preset safety period; and to reduce the pressure values ​​of the driving wheel and the driven wheel according to the pressure value descent rate.

[0108] Optionally, in another embodiment of the wireless transmission control device provided in this application, the following further includes:

[0109] The pre-current clamping force determination unit is used to set the pre-current clamping force of the steel belt of the continuously variable transmission of the target vehicle based on the current clamping force base value.

[0110] It should be noted that the specific working process of each module provided in the above embodiments of this application can be referred to the corresponding implementation methods in the above method embodiments, and will not be repeated here.

[0111] Another embodiment of this application provides an electronic device, including:

[0112] Memory, used to store executable instructions;

[0113] When a processor executes executable instructions stored in memory, it implements the continuously variable transmission control method described in the embodiments of this application.

[0114] Another embodiment of this application provides a computer-readable storage medium storing executable instructions for implementing the continuously variable transmission control method described above in the embodiments of this application when executed by a processor.

[0115] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0116] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control method of a continuously variable transmission, characterized by, The method includes: Based on the current road surface roughness level of the target vehicle and the correspondence between the road surface roughness level of the target vehicle and the basic value of the clamping force of the steel belt, the current clamping force of the target vehicle is determined; wherein, the road surface roughness level is a set of multiple levels that represent the degree of road surface roughness when the vehicle is traveling, and the correspondence is obtained in advance by fitting the actual torque value transmitted by the steel belt when the vehicle is traveling on the road surface corresponding to different road surface roughness levels. Based on the current driven pulley speed, the current difference in speed between the front and rear wheels, and the current difference in speed between the left and right wheels of the target vehicle, the current impact load of the target vehicle is calculated. The current speed of the drive pulley is obtained using the following formula. =MAX{ , , }; in, The current speed of the drive pulley, The current speed of the driven pulley. This represents the current difference in speed between the front and rear wheels. This represents the current difference in rotational speed between the left and right wheels. For the steel belt pulley speed ratio, The main reducer wheel speed ratio, The radius of the wheel; The current impact load is obtained using the following formula. =[ ( + )+ ( + )+ + ] ； in, The current impact load, It is the square of the ratio of the rate of change of the generator wheel speed to the rate of change of the turbine wheel speed. It is the square of the clutch speed ratio. For engine inertia, For pump wheel inertia, For turbine inertia, The moment of inertia of the clutch driving end. The moment of inertia of the driven end of the clutch. For the inertia of the active pulley, The current speed of the driving pulley; Based on the current impact load of the target vehicle, the required current clamping force of the target vehicle is calculated. Obtain the maximum value of the current clamping force between the current base value and the current required value of the current clamping force; Based on the maximum value of the current clamping force, the current clamping force of the steel belt of the continuously variable transmission of the target vehicle is set.

2. The method according to claim 1, characterized in that, The method further includes: Acquire and save the left drive wheel speed change rate and the right drive wheel speed change rate of the target vehicle in the current acquisition period; calculate the average wheel speed change rate of the target vehicle's drive wheels in the current acquisition period based on the average of the left drive wheel speed change rate and the right drive wheel speed change rate; The rolling average filtering process is applied to the left drive wheel speed change rate, the right drive wheel speed change rate, and the average drive wheel speed change rate within the current acquisition period to obtain the average left wheel speed change rate, the average right wheel speed change rate, and the average average wheel speed change rate. The rolling average filtering process is calculated based on the values ​​within the current acquisition period and the values ​​within at least one historical acquisition period to obtain the corresponding rolling arithmetic average. Obtain the maximum value of the wheel speed change rate among the average left wheel speed change rate, the average right wheel speed change rate, and the average wheel speed change rate; Based on the maximum value of the wheel speed change rate and the wheel speed change rate ranges corresponding to the multiple road surface bump levels, a target wheel speed change rate range is determined, and the road surface bump level corresponding to the target wheel speed change rate range is determined as the current road surface bump level.

3. The method according to claim 1, characterized in that, The method further includes: Based on the current clamping force of the steel belt, the pressure values ​​of the driving wheel and driven wheel of the continuously variable transmission of the target vehicle are set.

4. The method according to claim 3, characterized in that, When the current road surface bump level indicates no bumps, the method further includes: The pressure values ​​of the driving wheel and the driven wheel are maintained until the end of the delay period; wherein, the delay period is a preset safety period; Based on the rate of decrease in pressure value, reduce the pressure value of the driving wheel and the pressure value of the driven wheel.

5. The method according to claim 1, characterized in that, Before setting the current clamping force of the steel belt of the continuously variable transmission (CVT) of the target vehicle based on the maximum value of the current clamping force, the method further includes: Based on the current clamping force baseline value, the pre-current clamping force of the steel belt of the continuously variable transmission of the target vehicle is set.

6. A control device for a continuously variable transmission (CVT), characterized in that, The device includes: The current clamping force base value calculation unit is used to determine the current clamping force base value of the target vehicle based on the current road surface bump level of the target vehicle and the correspondence between the road surface bump level of the target vehicle and the clamping force base value of the steel belt; wherein, the road surface bump level is a set of multiple preset levels representing the degree of road surface bumps when the vehicle is traveling, and the correspondence is pre-fitted based on the actual torque value transmitted by the steel belt when the vehicle is traveling on the road surface corresponding to different road surface bump levels. The first unit for calculating the current impact load is used to calculate the current impact load of the target vehicle based on the current driven pulley speed, the current difference in speed between the front and rear wheels, and the current difference in speed between the left and right wheels. The second unit for calculating the current impact load is used to obtain the current speed of the driving pulley using the following formula. =MAX{ , , }; in, The current speed of the drive pulley, The current speed of the driven pulley. This represents the current difference in speed between the front and rear wheels. This represents the current difference in rotational speed between the left and right wheels. For the steel belt pulley speed ratio, The main reducer wheel speed ratio, The radius of the wheel; The current impact load is obtained using the following formula. =[ ( + )+ ( + )+ + ] ； in, The current impact load, It is the square of the ratio of the rate of change of the generator wheel speed to the rate of change of the turbine wheel speed. It is the square of the clutch speed ratio. For engine inertia, For pump wheel inertia, For turbine inertia, The moment of inertia of the clutch driving end. The moment of inertia of the driven end of the clutch. For the inertia of the active pulley, The current speed of the driving pulley; The current clamping force required value calculation unit is used to calculate the current clamping force required value of the target vehicle based on the current impact load of the target vehicle; The maximum value acquisition unit for current clamping force is used to acquire the maximum value of clamping force between the current basic value of clamping force and the current required value of clamping force. The current clamping force setting unit is used to set the current clamping force of the steel belt of the continuously variable transmission of the target vehicle based on the maximum value of the current clamping force.

7. An electronic device, characterized in that, include: Memory, used to store executable instructions; A processor, when executing executable instructions stored in the memory, implements the control method of the continuously variable transmission according to any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that, It stores executable instructions for implementing the control method of the continuously variable transmission as described in any one of claims 1 to 5 when executed by a processor.

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