A method and apparatus for ratio control of a continuously variable transmission

Abstract

The embodiment of the application discloses a speed ratio control method and device of a continuously variable transmission, the method comprising the following steps: firstly, obtaining the current speed ratio change rate, the current steady speed ratio clamping force and the current variable speed ratio clamping force of a target vehicle; then, obtaining the current steel belt stress value of the target vehicle according to the current steady speed ratio clamping force and the current variable speed ratio clamping force; and then, if the current steel belt stress value is greater than a steel belt stress threshold value, obtaining the current speed ratio change rate threshold value of the target vehicle; and if the absolute value of the current speed ratio change rate is greater than the current speed ratio change rate threshold value, adjusting the absolute value of the current speed ratio change rate to be not greater than the current speed ratio change rate threshold value. Through the above method, when the steel belt has a relatively large fatigue damage, the variable speed ratio clamping force on the steel belt can be adjusted by adjusting the numerical value of the current speed ratio change rate, thereby reducing the corresponding steel belt stress value, and the purpose of reducing the fatigue durability damage of the steel belt and increasing the durability life of the steel belt is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of vehicles, in particular to a speed ratio control method and device of a continuously variable transmission. BACKGROUND

[0002] In the field of vehicles, the traditional manual transmission and automatic transmission cannot currently achieve continuous change of transmission ratio, and thus it is difficult to maintain the optimal matching of the powertrain and engine of the vehicle. As a new type of power shift transmission, the continuously variable transmission (CVT) uses a transmission belt and primary and secondary driving wheels with variable diameters to cooperate to transmit power, and can achieve continuous change of transmission ratio, and thus the powertrain and engine of the vehicle can be matched with each other.

[0003] The current speed ratio control method of the continuously variable transmission is as follows: first, the target engine speed of the vehicle is determined according to the accelerator opening degree and vehicle speed of the vehicle, then the target speed ratio of the continuously variable transmission of the vehicle is calculated according to the target engine speed of the vehicle, and finally the current speed ratio of the continuously variable transmission is adjusted according to the target speed ratio of the continuously variable transmission. Although the current speed ratio control method of the continuously variable transmission can achieve the mutual matching of the continuously variable transmission and the engine, when the vehicle is running, various complex working conditions occur, and the steel belt of the continuously variable transmission has a large clamping force in large load and other working conditions. The large clamping force of the steel belt increases the fatigue and durability damage of the steel belt and reduces the durability life of the steel belt. SUMMARY

[0004] The embodiments of the present application provide a speed ratio control method and device of a continuously variable transmission, which can control the clamping force of the steel belt in large load and other working conditions, reduce the fatigue and durability damage of the steel belt, and increase the durability life of the steel belt.

[0005] Therefore, the first aspect of the embodiments of the present application provides a speed ratio control method of a continuously variable transmission, which comprises the following steps:

[0006] obtaining the current speed ratio change rate, the current steady speed ratio clamping force and the current variable speed ratio clamping force of a target vehicle; the current steady speed ratio clamping force represents the clamping force required by the steel belt of the continuously variable transmission of the target vehicle to maintain the current speed ratio, and the current variable speed ratio clamping force represents the clamping force required by the steel belt of the continuously variable transmission of the target vehicle due to the current speed ratio change rate;

[0007] obtaining the current steel belt stress value of the target vehicle according to the current steady speed ratio clamping force and the current variable speed ratio clamping force;

[0008] if the current steel belt stress value is greater than a steel belt stress threshold value, obtaining the current speed ratio change rate threshold value of the target vehicle; the steel belt stress threshold value represents the stress value corresponding to the durability strength of the steel belt of the vehicle.

[0009] if the absolute value of the current speed ratio change rate is greater than the current speed ratio change rate threshold, adjusting the absolute value of the current speed ratio change rate to be not greater than the current speed ratio change rate threshold.

[0010] The second aspect of the embodiment of the present application provides a speed ratio control device of a continuously variable transmission, and the device comprises:

[0011] The first obtaining unit is configured to obtain a current speed ratio change rate, a current steady speed ratio clamping force and a current variable speed ratio clamping force of a target vehicle; the current steady speed ratio clamping force represents a clamping force required by a steel belt of a continuously variable transmission of the target vehicle to maintain a current speed ratio, and the current variable speed ratio clamping force represents a clamping force required by the steel belt of the continuously variable transmission of the target vehicle due to the current speed ratio change rate;

[0012] The second obtaining unit is configured to obtain a current steel belt stress value of the target vehicle according to the current steady speed ratio clamping force and the current variable speed ratio clamping force;

[0013] The first judging unit is configured to obtain a current speed ratio change rate threshold of the target vehicle if the current steel belt stress value is greater than a steel belt stress threshold; the steel belt stress threshold represents a stress value corresponding to a durability strength of a steel belt of a vehicle;

[0014] The second judging unit is configured to adjust the absolute value of the current speed ratio change rate to be not greater than the current speed ratio change rate threshold if the absolute value of the current speed ratio change rate is greater than the current speed ratio change rate threshold.

[0015] The third aspect of the embodiment of the present application provides an electronic device, which comprises:

[0016] The memory is configured to store executable instructions;

[0017] The processor is configured to execute the executable instructions stored in the memory, and implement the speed ratio control method of the continuously variable transmission provided by the embodiment of the present application.

[0018] The fourth aspect of the embodiment of the present application provides a computer readable medium, which stores executable instructions, and is configured to be executed by a processor to implement the speed ratio control method of the continuously variable transmission provided by the embodiment of the present application.

[0019] As can be seen from the above technical solutions, the embodiment of the present application has the following advantages:

[0020] The embodiment of the present application discloses a kind of continuously variable transmission speed ratio control method and device, the method comprises: first, the current speed ratio change rate of target vehicle, current steady speed ratio clamping force and current speed ratio clamping force are obtained;Wherein, current steady speed ratio clamping force indicates the clamping force required for the steel band of the continuously variable transmission of target vehicle to maintain current speed ratio, current speed ratio clamping force indicates the clamping force required for the steel band of the continuously variable transmission of target vehicle due to current speed ratio change rate;Then, according to current steady speed ratio clamping force and current speed ratio clamping force, the current steel band stress value of target vehicle is obtained, the greater the clamping force of steel band, the greater the corresponding steel band stress value, the steel band stress value of the steel band of the continuously variable transmission in vehicle can be obtained by steady speed ratio clamping force and speed ratio clamping force;Then, if current steel band stress value is greater than steel band stress threshold value, the current speed ratio change rate threshold value of target vehicle is obtained;Wherein, steel band stress threshold value indicates the stress value corresponding to the endurance strength of the steel band of vehicle, when the above-mentioned current steel band stress value is greater than steel band stress threshold value, it indicates that the steel band will have greater fatigue damage at this time;If the absolute value of current speed ratio change rate is greater than current speed ratio change rate threshold value, adjust the absolute value of current speed ratio change rate to not greater than current speed ratio change rate threshold value, by adjusting the absolute value of current speed ratio change rate, the speed ratio clamping force on the steel band can be reduced, and then the current steel band stress value is reduced.Through the above method, when the current steel band stress value of steel band is greater than steel band stress threshold value and the absolute value of current speed ratio change rate is greater than current speed ratio change rate threshold value, i.e. when the steel band has greater fatigue damage in large load condition, the speed ratio clamping force on the steel band is adjusted by adjusting the value of current speed ratio change rate, and then the corresponding steel band stress value is reduced, to reduce the fatigue endurance damage of steel band and increase the endurance life of steel band. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on the provided drawings.

[0022] Figure 1 The stress-based Walter fatigue curve diagram provided by the embodiment of the present application;

[0023] Figure 2 The steel band stress value and clamping force and speed ratio relationship diagram provided by the embodiment of the present application;

[0024] Figure 3 The influence diagram of current speed ratio control method under large load condition provided by the embodiment of the present application;

[0025] Figure 4A flow chart of a speed ratio control method of a continuously variable transmission according to an embodiment of the present application is provided.

[0026] Figure 5 A flow chart of another speed ratio control method of a continuously variable transmission according to another embodiment of the present application is provided.

[0027] Figure 6 A flow chart of another speed ratio control method of a continuously variable transmission according to another embodiment of the present application is provided.

[0028] Figure 7 A speed ratio control effect diagram of a continuously variable transmission according to an embodiment of the present application is provided.

[0029] Figure 8 A schematic diagram of a speed ratio control device of a continuously variable transmission according to another embodiment of the present application is provided. DETAILED DESCRIPTION

[0030] In order to enable persons skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by persons skilled in the art without creative work fall within the scope of protection of the present application.

[0031] The terms "first", "second", "third", "fourth" and the like (if any) in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or a chronological sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in other than the order illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device that includes a list of steps or units does not necessarily limit to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to such processes, methods, products or devices.

[0032] Before the embodiments of the present application are further described in detail, the terms and phrases involved in the embodiments of the present application are explained, which are applicable to the following explanations.

[0033] Continuously Variable Transmission (CVT) is a new type of power shift transmission, which uses steel belt and main and driven wheels with variable working diameter to transmit power, so as to realize continuous change of speed ratio and optimal matching of transmission system and engine working condition.

[0034] Speed ratio, also known as transmitting ratio of motor, is the ratio of rotational speed of front and rear transmission mechanisms of vehicle transmission device. The speed ratio of CVT can be obtained by dividing input rotational speed of steel belt by output rotational speed of steel belt.

[0035] The current speed ratio control method of CVT is as follows: first, the engine target rotational speed of vehicle is determined according to the throttle opening and vehicle speed, then the target speed ratio of CVT of vehicle is calculated according to the engine target rotational speed of vehicle, and finally the current speed ratio of CVT is adjusted according to the target speed ratio of CVT. Although the current speed ratio control method of CVT can realize mutual matching of CVT and engine, when the vehicle is running, various complex working conditions will occur, and the steel belt of CVT will have large clamping force in large load working condition, so that the large clamping force of steel belt will increase fatigue damage of steel belt and reduce fatigue life of steel belt.

[0036] Specifically, first, referring to Figure 1 , Figure 1 a stress-based Walser fatigue curve provided by the embodiment of the application is shown. As can be seen from Figure 1 , at the same number of load cycles, the larger the load amplitude of steel belt, the higher the failure probability. That is, the fatigue life of steel belt depends on the load amplitude of steel belt, that is, the stress value of steel belt.

[0037] Then, referring to Figure 2 , Figure 2 a diagram showing the relationship between the stress value of steel belt and clamping force and speed ratio is provided by the embodiment of the application. As can be seen from Figure 2 , at the same speed ratio, the larger the clamping force of steel belt, the larger the stress value of steel belt, and the larger the fatigue damage of steel belt; at the same clamping force, small or large speed ratio will lead to large stress value of steel belt, and further increase fatigue damage of steel belt. That is, the stress value of steel belt is related to clamping force and speed ratio.

[0038] Finally, referring to Figure 3 , Figure 3 a diagram showing the influence of the current speed ratio control method in large load working condition is provided by the embodiment of the application. When the CVT is in full throttle, traction control system (TCS), high torque and other large load working conditions, the steel belt will have large fatigue damage, and Figure 3It can be seen that in the current speed ratio control method of the continuously variable transmission, in the large throttle starting working condition, the vehicle speed will naturally increase, and the output speed of the steel belt will also naturally increase. The input speed is the input speed of the steel belt, and the steel belt of the continuously variable transmission is usually connected with the engine through the main reducer. The input speed is related to the target speed of the main reducer and the engine of the vehicle. After starting with large throttle, the input speed will be increased to reach the corresponding target input speed. Since the speed ratio value is equal to the above-mentioned input speed value divided by the above-mentioned output speed value, in the large throttle starting working condition, the speed ratio will decrease with the increase of the vehicle speed, and since the input speed will remain unchanged after reaching the target input speed, the absolute value of the speed ratio change rate will be larger at this time, that is, the required speed ratio clamping force of the speed ratio change rate will be larger, and finally the steel belt stress value will be larger, increasing the fatigue durability damage of the steel belt.

[0039] Figure 3 b is a schematic diagram of related data of the vehicle when the traction control system (TCS) is working. When the vehicle is running, there will be a phenomenon of slipping. When the vehicle slips, the TCS system of the vehicle will be activated. At this time, since the vehicle speed will increase instantaneously when the vehicle slips, the driver will usually reduce the vehicle speed by reducing the throttle data for safety reasons, so the vehicle speed will first increase and then decrease, and the output speed of the steel belt will also first increase and then decrease. With the reduction of the throttle data, the target speed of the engine will also decrease, and the target input speed of the steel belt will also decrease. Since the speed ratio value is equal to the above-mentioned input speed value divided by the above-mentioned output speed value, the speed ratio will first decrease and then increase, and the speed ratio change rate will first be a larger negative value. The required speed ratio clamping force of the speed ratio change rate will be larger, and finally the steel belt stress value will be larger, increasing the fatigue durability damage of the steel belt.

[0040] In summary, since the larger the speed ratio change rate is, the larger the corresponding clamping force of the speed ratio is, in the full throttle, TCS, high torque and other large load working conditions, there is a speed change demand, and the speed ratio clamping force of the steel belt will be larger, that is, the steel belt stress value will be larger, increasing the fatigue durability damage of the steel belt and reducing the fatigue durability life of the steel belt.

[0041] In view of this, this application discloses a speed ratio control method and apparatus for a continuously variable transmission (CVT). The method includes: first, acquiring the current speed ratio change rate, the current steady-state ratio clamping force, and the current gear ratio clamping force of the target vehicle; wherein, the current steady-state ratio clamping force represents the clamping force required by the CVT steel belt of the target vehicle to maintain the current speed ratio, and the current gear ratio clamping force represents the clamping force required by the CVT steel belt of the target vehicle due to the current speed ratio change rate; then, based on the current steady-state ratio clamping force and the current gear ratio clamping force, obtaining the current steel belt stress value of the target vehicle, wherein the greater the clamping force of the steel belt, the greater the corresponding steel belt stress value; and controlling the speed ratio by adjusting the steady-state ratio clamping force and the gear ratio clamping force. The clamping force can be used to obtain the stress value of the steel belt in the continuously variable transmission (CVT) of the vehicle. Then, if the current steel belt stress value is greater than the steel belt stress threshold, the current speed ratio change rate threshold of the target vehicle is obtained. Here, the steel belt stress threshold represents the stress value corresponding to the durability strength of the vehicle's steel belt. When the current steel belt stress value is greater than the steel belt stress threshold, it indicates that the steel belt will have significant fatigue damage. If the absolute value of the current speed ratio change rate is greater than the current speed ratio change rate threshold, the absolute value of the current speed ratio change rate is adjusted to be no greater than the current speed ratio change rate threshold. By adjusting the absolute value of the current speed ratio change rate, the gear ratio clamping force on the steel belt can be reduced, thereby reducing the current steel belt stress value. By using the above method, when the current steel belt stress value is greater than the steel belt stress threshold and the absolute value of the current speed ratio change rate is greater than the current speed ratio change rate threshold, that is, when the steel belt will have significant fatigue damage under heavy load and other working conditions, the speed ratio clamping force on the steel belt can be adjusted by adjusting the value of the current speed ratio change rate, thereby reducing the corresponding steel belt stress value, achieving the purpose of reducing steel belt fatigue durability damage and increasing steel belt durability life.

[0042] The speed ratio 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 speed ratio control method for a continuously variable transmission (CVT) provided in this application embodiment is shown. The speed ratio control method for a CVT provided in this application embodiment includes the following steps:

[0043] S401. Obtain the current speed ratio change rate, current steady speed ratio clamping force, and current gear ratio clamping force of the target vehicle; the current steady speed ratio clamping force represents the clamping force required by the steel belt of the continuously variable transmission (CVT) of the target vehicle to maintain the current speed ratio, and the current gear ratio clamping force represents the clamping force required by the steel belt of the CVT of the target vehicle due to the current speed ratio change rate.

[0044] S402. Based on the current steady speed ratio clamping force and the current gear ratio clamping force, obtain the current steel belt stress value of the target vehicle.

[0045] Specifically, the current steady ratio clamping force of the vehicle represents the clamping force required for the steel belt of the continuously variable transmission to maintain the current speed ratio when the vehicle is running, and the current speed ratio clamping force represents the clamping force required for the steel belt of the continuously variable transmission due to the current speed ratio change rate when the vehicle is running. Generally, the sum of the current steady ratio clamping force and the current speed ratio clamping force can represent the current steel belt stress value of the vehicle, and the service condition of the steel belt of the vehicle can be obtained by analyzing the current steel belt stress value of the vehicle.

[0046] S403, if the current steel belt stress value is greater than the steel belt stress threshold value, obtaining the current speed ratio change rate threshold value of the target vehicle; the steel belt stress threshold value represents the stress value corresponding to the endurance strength of the steel belt of the vehicle.

[0047] Specifically, when the above-mentioned current steel belt stress value is greater than the steel belt stress threshold value of the vehicle, that is, when the steel belt stress value of the vehicle is large, the steel belt of the vehicle has a large fatigue damage, and the current speed ratio change rate threshold value of the vehicle can be obtained.

[0048] It should be noted that since the speed ratio during the running of the vehicle will generally change, the corresponding steady ratio clamping force will also change, and the sum of the steady ratio clamping force and the speed ratio clamping force is generally the clamping force of the steel belt. When the steady ratio clamping force changes, the allowable speed ratio clamping force of the steel belt of the continuously variable transmission will also change, so the current speed ratio change rate threshold value of the vehicle will generally change.

[0049] Optionally, the current speed ratio change rate threshold value can be calculated according to the current steady ratio clamping force.

[0050] Specifically, since the sum of the steady ratio clamping force and the speed ratio clamping force of the vehicle is generally the clamping force of the steel belt, the clamping force of the steel belt is limited by the steel belt stress threshold value, and the speed ratio clamping force of the vehicle is related to the speed ratio change rate of the vehicle, so the current speed ratio change rate threshold value can be obtained according to the current steady ratio clamping force of the vehicle. For example, the corresponding fitting relationship between the steady ratio clamping force and the speed ratio change rate threshold value of the vehicle can be obtained by pre-experimenting multiple times.

[0051] Optionally, according to the current steady ratio clamping force, the current speed ratio change rate threshold value can be calculated in the following manner, as shown in Figure 5 , and Figure 5 Another flowchart of another continuously variable transmission speed ratio control method provided by another embodiment of the present application includes:

[0052] S501, obtaining the current speed ratio clamping force threshold value based on the current steady ratio clamping force and the speed ratio clamping force threshold table; the speed ratio clamping force threshold table represents the corresponding relationship between the steady ratio clamping force and the speed ratio clamping force threshold value of the target vehicle.

[0053] Specifically, since the sum of the steady speed ratio clamping force and the variable speed ratio clamping force of the vehicle is usually the clamping force of the steel belt, the clamping force of the steel belt is limited by the steel belt stress threshold, and therefore, the current variable speed ratio clamping force threshold of the vehicle, i.e., the variable speed ratio clamping force currently allowable by the vehicle, can be obtained through the current steady speed ratio clamping force and the variable speed ratio clamping force threshold table of the vehicle.

[0054] S502, obtaining a current variable speed ratio characteristic parameter according to the current variable speed ratio influence parameter of the target vehicle and a variable speed ratio characteristic parameter table; wherein the variable speed ratio influence parameter comprises a current oil temperature, a current torque, a current input speed and a current speed ratio of the target vehicle, and the variable speed ratio characteristic parameter table represents a corresponding relationship between the variable speed ratio influence parameter and the variable speed ratio characteristic parameter of the target vehicle.

[0055] Specifically, the variable speed ratio characteristic parameter of the vehicle represents the relationship between the variable speed ratio clamping force and the speed ratio change rate of the vehicle, and is related to the oil temperature, the torque, the input speed and the speed ratio of the vehicle. The current variable speed ratio characteristic parameter can be obtained through the current oil temperature, the current torque, the current input speed, the current speed ratio of the vehicle and the variable speed ratio characteristic parameter table.

[0056] S503, dividing the current variable speed ratio clamping force threshold by the current variable speed ratio characteristic parameter to obtain a current speed ratio change rate threshold.

[0057] Specifically, the current speed ratio change rate threshold can be accurately obtained by dividing the current variable speed ratio clamping force threshold by the current variable speed ratio characteristic parameter, thereby improving the reliability of the subsequent steps.

[0058] S404, if the absolute value of the current speed ratio change rate is greater than the current speed ratio change rate threshold, adjusting the absolute value of the current speed ratio change rate to be not greater than the current speed ratio change rate threshold.

[0059] It should be noted that when the speed ratio decreases, the speed ratio change rate is negative; when the speed ratio increases, the speed ratio change rate is positive, and by comparing the absolute value of the current speed ratio change rate with the current speed ratio change rate threshold, the value of the current speed ratio change rate can be analyzed. When the absolute value of the current speed ratio change rate is greater than the current speed ratio change rate threshold, it can be judged that the value of the current speed ratio change rate is large at this time, and the absolute value, i.e., the value of the current speed ratio change rate, can be adjusted to be not greater than the current speed ratio change rate threshold.

[0060] By adjusting the current speed ratio change rate threshold, the corresponding variable speed ratio clamping force can be reduced, and thus the steel belt stress value of the steel belt can be reduced, so as to achieve the purpose of reducing the fatigue durability damage of the steel belt and increasing the durability life of the steel belt.

[0061] Optionally, the current input speed and current throttle data of the target vehicle can be obtained; based on the current throttle data, the current target input speed of the target vehicle can be obtained; the absolute value of the current speed ratio change rate can be adjusted to be no greater than the current speed ratio change rate threshold until the current input speed value is equal to the current target input speed value.

[0062] Specifically, based on the vehicle's throttle data, the target engine speed can be obtained, which in turn allows us to determine the target input speed of the vehicle's belt. Since the belt's input speed remains constant once the target speed is reached, and the vehicle speed typically remains constant or changes only slightly during normal, stable driving, the gear ratio will also remain constant or change only slightly, meaning the gear ratio change rate is zero or minimal. Therefore, when the current belt stress value exceeds the belt stress threshold and the absolute value of the current gear ratio change rate exceeds the current gear ratio change rate threshold, the current gear ratio change rate can be adjusted until the vehicle's current input speed equals the aforementioned target input speed value—that is, when the gear ratio change rate is zero or minimal. At this point, further adjustment of the current gear ratio change rate is unnecessary.

[0063] It should be noted that if the current steel strip stress value is greater than the steel strip stress threshold again and the absolute value of the current speed ratio change rate is greater than the current speed ratio change rate threshold again after not adjusting the current speed ratio change rate, the current speed ratio change rate should be adjusted again.

[0064] Optionally, before adjusting the current speed ratio change rate to no greater than the current speed ratio change rate threshold, the speed ratio of the continuously variable transmission (CVT) can be controlled in the following manner, see [reference]. Figure 6 , Figure 6 A flowchart of another continuously variable transmission (CVT) speed ratio control method provided in another embodiment of this application includes:

[0065] S601, Obtain the current speed ratio of the target vehicle.

[0066] S602. If the current speed ratio is greater than the preset speed ratio threshold, obtain the current vehicle speed and current throttle data of the target vehicle, and obtain the current vehicle speed threshold based on the current throttle data and the vehicle speed threshold table; the preset speed ratio threshold is preset based on the durability strength of the steel belt of the target vehicle, and the vehicle speed threshold table represents the correspondence between the throttle data of the target vehicle and the vehicle speed threshold.

[0067] Specifically, see Figure 2, the greater the speed ratio of the steel belt of the vehicle, the greater the clamping force of the steel belt. According to the endurance strength of the steel belt, a preset speed ratio threshold of the steel belt can be set, which represents the maximum allowable speed ratio of the steel belt of the vehicle. If the current speed ratio is greater than the preset speed ratio threshold, the current vehicle speed and the current throttle data of the vehicle can be obtained. Since the throttle data is related to the target speed of the engine of the vehicle, that is, the throttle data is related to the input speed of the steel belt of the vehicle, and the vehicle speed is related to the output speed of the steel belt, the input speed of the steel belt divided by the output speed is the speed ratio of the steel belt, which cannot be greater than the preset speed ratio threshold, so according to the current throttle data and the speed threshold table, the current speed threshold can be obtained, which represents the maximum allowable speed of the current vehicle under the current throttle data.

[0068] S603, if the current speed is greater than the current speed threshold, the current input speed change rate of the target vehicle is reduced.

[0069] Specifically, if the current speed is greater than the current speed threshold, that is, the vehicle speed is also greater than the maximum allowable speed of the vehicle under the current throttle data when the speed ratio is greater than the maximum allowable speed ratio, the current input speed change rate of the vehicle can be reduced to allow the vehicle to reach the target input speed of the vehicle at a smaller input speed change rate, so as to adjust the speed ratio change rate in advance.

[0070] It should be noted that the vehicle speed is also greater than the maximum allowable speed of the vehicle under the current throttle data when the speed ratio is greater than the maximum allowable speed ratio, which is usually a working condition that the clamping force of the steel belt can be estimated in advance, for example, the large throttle starting condition of the vehicle. In the working condition that the clamping force of the steel belt can be estimated in advance, in addition to directly adjusting the current speed ratio change rate, the vehicle can also reduce the input speed change rate of the steel belt of the vehicle to allow the vehicle to reach the target input speed of the vehicle at a smaller input speed change rate, thereby reducing the speed ratio change rate by reducing the input speed change rate.

[0071] Optionally, the current target input speed of the target vehicle can be obtained according to the current throttle data; the current input speed of the target vehicle is obtained; the current input speed change rate of the target vehicle is reduced until the current input speed value is equal to the current target input speed value.

[0072] Specifically, when the speed ratio is greater than the maximum allowable speed ratio, the current input speed change rate of the vehicle can be reduced to allow the vehicle to reach the target input speed of the vehicle at a smaller input speed change rate, and when the current input speed of the vehicle reaches the target input speed, the current input speed change rate of the vehicle does not need to be adjusted.

[0073] Optionally, the clamping force of the target vehicle can be provided by the drive pulley cylinder or the driven pulley cylinder of the continuously variable transmission of the target vehicle.

[0074] Specifically, the clamping force of the target vehicle can be provided by the drive pulley cylinder or the driven pulley cylinder of the continuously variable transmission of the target vehicle. Generally, the drive pulley cylinder of the continuously variable transmission can provide the clamping force of the target vehicle. If the required clamping force of the target vehicle is less than the minimum driving force corresponding to the safe driving of the drive pulley cylinder, the driving force of the driven pulley cylinder can be increased and the driving force of the drive pulley cylinder can be correspondingly increased, so that the difference between the driving force of the drive pulley cylinder and the driving force of the driven pulley cylinder can provide the required clamping force of the target vehicle.

[0075] The speed ratio control method of the continuously variable transmission provided by the embodiments of the present application can reduce the fatigue damage of the vehicle by reducing the clamping force of the vehicle under heavy load conditions. Specifically, referring to Figure 7 , Figure 7 The speed ratio control effect diagram of the continuously variable transmission provided by the embodiments of the present application is shown in the figure. The conventional strategy is the conventional speed ratio control method currently adopted, and the new strategy is the speed ratio control method provided by the present application.

[0076] As shown in Figure 7 a, the speed ratio control method of the continuously variable transmission provided by the present application can control the absolute value of the speed ratio change rate of the steel belt of the continuously variable transmission of the vehicle to be less than the current speed ratio change rate threshold under the large throttle starting condition of the vehicle. The current speed ratio change rate is not a constant value that is fixed and unchanged. In order to facilitate understanding, the speed ratio change rate at different times is set to the same value in the diagram. As can be seen from the diagram, by adjusting the size of the absolute value of the speed ratio change rate, the size of the clamping force of the transmission ratio of the vehicle can be reduced.

[0077] It should be noted that Figure 7 The large throttle starting condition shown in a is usually a condition in which the vehicle has just started and the vehicle speed is small, i.e. the output speed of the steel belt is small. The speed ratio of the steel belt is equal to the input speed of the steel belt of the vehicle divided by the output speed of the steel belt. Therefore, the speed ratio of the steel belt of the vehicle is large, i.e. the current speed ratio of the vehicle is greater than the preset speed ratio threshold. If the vehicle speed increases to be greater than the current vehicle speed threshold at this time, the current input speed change rate of the vehicle can be reduced, as shown in Figure 7 a, the input speed reaches the target input speed at a relatively gentle change rate, so that the speed ratio change rate is adjusted in advance to reduce the adverse effect of the speed ratio change rate on drivability.

[0078] As shown in Figure 7As shown in FIG. 8B, the vehicle in the TCS activation condition adopts the speed ratio control method of the continuously variable transmission provided in the present application, and the absolute value of the speed ratio change rate of the steel belt of the continuously variable transmission of the vehicle can be controlled to be less than the current speed ratio change rate threshold. Wherein, since the speed ratio change rate of the speed ratio control method provided in the present application is less than the speed ratio change rate of the currently adopted speed ratio control method, the time for the speed ratio control method provided in the present application to reach the target speed ratio will be greater than the time for the currently adopted speed ratio control method to reach the target speed ratio, which will have certain influence on the drivability.

[0079] The embodiment of the present application discloses a speed ratio control method and device of a continuously variable transmission, which comprises the following steps: firstly, obtaining the current speed ratio change rate, the current steady speed ratio clamping force and the current variable speed ratio clamping force of a target vehicle; then, obtaining the current steel belt stress value of the target vehicle according to the current steady speed ratio clamping force and the current variable speed ratio clamping force; and then, if the current steel belt stress value is greater than the steel belt stress threshold, obtaining the current speed ratio change rate threshold of the target vehicle; and if the absolute value of the current speed ratio change rate is greater than the current speed ratio change rate threshold, adjusting the absolute value of the current speed ratio change rate to be not greater than the current speed ratio change rate threshold. Through the above method, when the steel belt has relatively large fatigue damage, the variable speed ratio clamping force on the steel belt can be adjusted by adjusting the value of the current speed ratio change rate, so as to reduce the corresponding steel belt stress value, thereby achieving the purpose of reducing the fatigue durability damage of the steel belt and increasing the durability life of the steel belt.

[0080] Another embodiment of the present application provides a speed ratio control device of a continuously variable transmission, as shown in FIG. 9, Figure 8 Figure 8 FIG. 10 is a schematic diagram of a speed ratio control device of a continuously variable transmission provided in another embodiment of the present application, which comprises:

[0081] The first obtaining unit 801 is configured to obtain the current speed ratio change rate, the current steady speed ratio clamping force and the current variable speed ratio clamping force of a target vehicle; the current steady speed ratio clamping force represents the clamping force required by the steel belt of the continuously variable transmission of the target vehicle to maintain the current speed ratio, and the current variable speed ratio clamping force represents the clamping force required by the steel belt of the continuously variable transmission of the target vehicle due to the current speed ratio change rate;

[0082] The second obtaining unit 802 is configured to obtain the current steel belt stress value of the target vehicle according to the current steady speed ratio clamping force and the current variable speed ratio clamping force;

[0083] The first judging unit 803 is configured to obtain the current speed ratio change rate threshold of the target vehicle if the current steel belt stress value is greater than the steel belt stress threshold; the steel belt stress threshold represents the stress value corresponding to the durability strength of the steel belt of the vehicle;

[0084] ​The second judging unit 804 is configured to adjust the absolute value of the current speed ratio change rate to be not greater than the current speed ratio change rate threshold if the absolute value of the current speed ratio change rate is greater than the current speed ratio change rate threshold.

[0085] Optionally, in the speed ratio control device of the wireless transmission provided in another embodiment of the present application, the first judging unit is further configured to calculate the current speed ratio change rate threshold according to the current steady speed ratio clamping force.

[0086] Optionally, in the speed ratio control device of the wireless transmission provided in another embodiment of the present application, the first judging unit is further configured to obtain the current transmission ratio clamping force threshold based on the current steady speed ratio clamping force and a transmission ratio clamping force threshold table, the transmission ratio clamping force threshold table representing a corresponding relationship between the steady speed ratio clamping force of the target vehicle and the transmission ratio clamping force threshold; obtain the current transmission ratio characteristic parameter according to the current transmission ratio influencing parameter of the target vehicle and a transmission ratio characteristic parameter table, the transmission ratio influencing parameter including the current oil temperature, the current torque, the current input rotation speed and the current speed ratio of the target vehicle, the transmission ratio characteristic parameter table representing a corresponding relationship between the transmission ratio influencing parameter and the transmission ratio characteristic parameter of the target vehicle; and divide the current transmission ratio clamping force threshold by the current transmission ratio characteristic parameter to obtain the current speed ratio change rate threshold.

[0087] Optionally, in the speed ratio control device of the wireless transmission provided in another embodiment of the present application, the device further comprises:

[0088] The stopping unit is configured to obtain the current input rotation speed and the current throttle data of the target vehicle; and obtain the current target input rotation speed of the target vehicle based on the current throttle data.

[0089] The second judging unit is further configured to adjust the absolute value of the current speed ratio change rate to be not greater than the current speed ratio change rate threshold until the current input rotation speed value is equal to the current target input rotation speed value.

[0090] Optionally, in the speed ratio control device of the wireless transmission provided in another embodiment of the present application, the device further comprises:

[0091] The decreasing unit is configured to obtain the current speed ratio of the target vehicle; obtain the current vehicle speed and the current throttle data of the target vehicle if the current speed ratio is greater than a preset speed ratio threshold, and obtain the current vehicle speed threshold according to the current throttle data and a vehicle speed threshold table; the preset speed ratio threshold is preset according to the endurance strength of the steel belt of the target vehicle, and the vehicle speed threshold table represents a corresponding relationship between the throttle data and the vehicle speed threshold of the target vehicle; and decrease the current input rotation speed change rate of the target vehicle if the current vehicle speed is greater than the current vehicle speed threshold.

[0092] Optionally, in the speed ratio control device of the wireless transmission provided in another embodiment of the present application, the device further comprises:

[0093] The stopping unit is configured to obtain a current target input speed of the target vehicle according to the current throttle data, and obtain a current input speed of the target vehicle.

[0094] The second judging unit is further configured to reduce a current input speed change rate of the target vehicle until the current input speed value is equal to the current target input speed value.

[0095] Optionally, in the speed ratio control device of the wireless transmission provided by another embodiment of the present application, the device further comprises:

[0096] The providing unit is configured to provide the clamping force of the target vehicle through the driving pulley cylinder or the driven pulley cylinder of the continuously variable transmission of the target vehicle.

[0097] It should be noted that the specific working process of each module provided by the above embodiments of the present application can be correspondingly referred to the corresponding embodiments in the above method embodiments, which will not be described here.

[0098] Another embodiment of the present application provides an electronic device, comprising:

[0099] The memory is configured to store executable instructions;

[0100] The processor is configured to execute the executable instructions stored in the memory, and implement the continuously variable transmission speed ratio control method provided by the embodiments of the present application.

[0101] Another embodiment of the present application provides a computer readable storage medium, which stores executable instructions, and is configured to be executed by a processor to implement the continuously variable transmission speed ratio control method provided by the embodiments of the present application.

[0102] The skilled person can further realize that the units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein can be realized by electronic hardware, computer software or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the components and steps of the examples have been described in general terms in the above description. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. The skilled person can use different methods to realize the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0103] The foregoing description of the disclosed embodiments enables a person skilled in the art to make or use the application. Modifications of these embodiments will occur to persons of skill in the art, and that the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Therefore, the present application is not intended 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 speed ratio control method of a continuously variable transmission, characterized by, The method comprises: obtaining a current speed ratio change rate, a current steady speed ratio clamping force and a current shift ratio clamping force of a target vehicle; the current steady speed ratio clamping force represents a clamping force required by a steel belt of a continuously variable transmission of the target vehicle to maintain a current speed ratio, and the current shift ratio clamping force represents a clamping force required by the steel belt of the continuously variable transmission of the target vehicle due to the current speed ratio change rate; obtaining a current steel belt stress value of the target vehicle according to the current steady speed ratio clamping force and the current shift ratio clamping force; if the current steel belt stress value is greater than a steel belt stress threshold value, obtaining a current speed ratio change rate threshold value of the target vehicle; the steel belt stress threshold value represents a stress value corresponding to a durability strength of a steel belt of a vehicle; if an absolute value of the current speed ratio change rate is greater than the current speed ratio change rate threshold value, adjusting the absolute value of the current speed ratio change rate to be not greater than the current speed ratio change rate threshold value.

2. The method of claim 1, wherein, The method further comprises: obtaining a current speed ratio change rate threshold value of the target vehicle according to the current steady speed ratio clamping force.

3. The method of claim 2, wherein, The method further comprises: obtaining a current shift ratio clamping force threshold value based on the current steady speed ratio clamping force and a shift ratio clamping force threshold value table; the shift ratio clamping force threshold value table represents a corresponding relationship between the steady speed ratio clamping force and the shift ratio clamping force threshold value of the target vehicle; obtaining a current shift ratio characteristic parameter according to a current shift ratio influencing parameter of the target vehicle and a shift ratio characteristic parameter table; the shift ratio influencing parameter comprises a current oil temperature, a current torque, a current input rotation speed and a current speed ratio of the target vehicle, and the shift ratio characteristic parameter table represents a corresponding relationship between the shift ratio influencing parameter and the shift ratio characteristic parameter of the target vehicle; dividing the current shift ratio clamping force threshold value by the current shift ratio characteristic parameter to obtain the current speed ratio change rate threshold value.

4. The method of claim 1, wherein, The method further comprises: obtaining current input rotation speed and current throttle data of the target vehicle; obtaining a current target input rotation speed of the target vehicle based on the current throttle data; The method further comprises: adjusting the absolute value of the current speed ratio change rate to be not greater than the current speed ratio change rate threshold value until a numerical value of the current input rotation speed is equal to a numerical value of the current target input rotation speed.

5. The method of claim 1, wherein, Before the adjusting the current speed ratio change rate to be not greater than the current speed ratio change rate threshold value, the method further comprises: obtaining a current speed ratio of the target vehicle; if the current speed ratio is greater than a preset speed ratio threshold value, obtaining current vehicle speed and current throttle data of the target vehicle, and obtaining a current vehicle speed threshold value according to the current throttle data and a vehicle speed threshold value table; the preset speed ratio threshold value is preset according to a durability strength of a steel belt of the target vehicle, and the vehicle speed threshold value table represents a corresponding relationship between the throttle data and the vehicle speed threshold value of the target vehicle; if the current vehicle speed is greater than the current vehicle speed threshold value, reducing a current input rotation speed change rate of the target vehicle.

6. The method of claim 5, wherein, The method further comprises: According to the current throttle data, a current target input speed of the target vehicle is obtained; A current input speed of the target vehicle is obtained; The current input speed variation rate of the target vehicle is reduced, comprising: The current input speed variation rate of the target vehicle is reduced until the value of the current input speed is equal to the value of the current target input speed.

7. The method of claim 1, wherein, The method further comprises: The clamping force of the target vehicle is provided through a driving pulley cylinder or a driven pulley cylinder of a continuously variable transmission of the target vehicle.

8. A speed ratio control device for a continuously variable transmission, characterized by comprising: The device comprises: A first obtaining unit is configured to obtain a current speed ratio variation rate, a current steady speed ratio clamping force and a current variable speed ratio clamping force of a target vehicle; the current steady speed ratio clamping force represents a clamping force required by a steel belt of a continuously variable transmission of the target vehicle to maintain a current speed ratio, and the current variable speed ratio clamping force represents a clamping force required by the steel belt of the continuously variable transmission of the target vehicle due to the current speed ratio variation rate; A second obtaining unit is configured to obtain a current steel belt stress value of the target vehicle according to the current steady speed ratio clamping force and the current variable speed ratio clamping force; A first judging unit is configured to obtain a current speed ratio variation rate threshold of the target vehicle if the current steel belt stress value is greater than a steel belt stress threshold; the steel belt stress threshold represents a stress value corresponding to a durability strength of the steel belt of the vehicle; A second judging unit is configured to adjust an absolute value of the current speed ratio variation rate to be not greater than the current speed ratio variation rate threshold if the absolute value of the current speed ratio variation rate is greater than the current speed ratio variation rate threshold.

9. An electronic device, comprising: The device comprises: A memory is configured to store executable instructions; A processor is configured to execute the executable instructions stored in the memory to implement the continuously variable transmission speed ratio control method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, Executable instructions are stored in the memory, and the executable instructions are configured to be executed by the processor to implement the continuously variable transmission speed ratio control method according to any one of claims 1 to 7.

Images