Speed ratio control method and device of continuously variable transmission, storage medium and electronic equipment

Abstract

The application provides a speed ratio control method and device of a continuously variable transmission (CVT), a storage medium and an electronic device, and the method comprises the following steps: acquiring a current target rotating speed of the CVT, and determining whether the CVT meets a speed ratio control condition based on the target rotating speed; when the condition is met, determining a current target speed ratio of the CVT; determining a target speed ratio change rate of the target speed ratio, periodically adjusting a change rate of the target speed ratio change rate based on a speed ratio limiting strategy, and adjusting the speed ratio of the CVT according to a limited speed ratio change rate obtained after the adjustment until the speed ratio of the CVT reaches the target speed ratio. According to the speed ratio limiting strategy, the change rate of the target speed ratio change rate is periodically adjusted, and the speed ratio of the CVT is adjusted according to the limited speed ratio change rate after the adjustment, so that the speed ratio of the CVT can be smoothly switched to the target speed ratio, thereby effectively reducing the flow fluctuation of the system, delaying the aging of the CVT and prolonging the service life.

Description

Technical Field

[0001] This invention relates to the field of engine technology, and in particular to a method and apparatus for controlling the speed ratio of a continuously variable transmission (CVT), a storage medium, and electronic equipment. Background Technology

[0002] As a new type of power shift transmission, the continuously variable transmission (CVT) boasts advantages such as driving comfort, low emissions, good fuel economy, and stepless shifting, making it a promising market prospect. In particular, the CVT achieves a dynamic and optimal match between vehicle driving resistance and engine load through continuous changes in the speed ratio, ensuring the engine always operates in its high-efficiency range and maximizing its potential according to the driver's intended operation.

[0003] When controlling the speed ratio of a continuously variable transmission (CVT) using traditional control methods, there is a situation where the CVT speed ratio changes drastically. When the CVT speed ratio changes rapidly, it is prone to sharp flow fluctuations, which can accelerate the aging of the CVT and reduce its service life. Summary of the Invention

[0004] In view of this, the present invention provides a speed ratio control method and device, storage medium and electronic device for a continuously variable transmission (CVT). By adjusting the rate of change of the target speed ratio, the speed ratio of the CVT can be smoothly adjusted to the target speed ratio, reducing flow fluctuations, delaying CVT aging, and extending the service life of the CVT.

[0005] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0006] The first aspect of this application discloses a speed ratio control method for a continuously variable transmission (CVT), comprising:

[0007] Obtain the current target speed of the continuously variable transmission (CVT), and based on the target speed, determine whether the CVT meets the preset speed ratio control conditions;

[0008] When it is determined that the continuously variable transmission (CVT) meets the preset speed ratio control conditions, the current target speed ratio of the CVT is determined.

[0009] The target speed ratio change rate is determined, and based on a preset speed ratio limiting strategy, the change rate of the target speed ratio change rate is periodically adjusted. The speed ratio of the continuously variable transmission is then adjusted according to the adjusted limiting speed ratio change rate until the speed ratio of the continuously variable transmission reaches the target speed ratio.

[0010] Optionally, in the above method, obtaining the current target speed of the continuously variable transmission includes:

[0011] Obtain the current throttle opening and vehicle speed of the vehicle to which the continuously variable transmission belongs;

[0012] The throttle opening and vehicle speed of the vehicle are processed to obtain the target speed of the continuously variable transmission (CVT).

[0013] Optionally, in the above method, determining whether the continuously variable transmission (CVT) meets the preset speed ratio control conditions based on the target speed includes:

[0014] Obtain the current input shaft speed of the continuously variable transmission;

[0015] Determine the speed difference between the input shaft speed and the target speed;

[0016] Determine whether the speed difference is greater than or equal to a preset difference;

[0017] When the speed difference is greater than or equal to the preset difference, the continuously variable transmission is determined to meet the preset speed ratio control conditions.

[0018] Optionally, in the above method, determining the current target speed ratio of the continuously variable transmission includes:

[0019] The target speed and the input shaft speed are processed to obtain the current target speed ratio of the continuously variable transmission.

[0020] Optionally, the above method includes periodically adjusting the rate of change of the target speed ratio change based on a preset speed ratio limiting strategy, and adjusting the speed ratio of the continuously variable transmission (CVT) according to the adjusted limiting speed ratio change rate until the speed ratio of the CVT reaches the target speed ratio, comprising:

[0021] Determine the initial control period, and designate the initial control period as the first control period;

[0022] Obtain each first control parameter corresponding to the first control cycle;

[0023] Based on each of the first control parameters, a first limit range of the rate of change of the target speed ratio corresponding to the first control cycle is obtained;

[0024] A first limiting parameter corresponding to the first control cycle is determined, and based on the first limiting parameter and the first limiting range, a first limiting value for the rate of change of the target speed ratio corresponding to the first control cycle is determined.

[0025] Determine the first limit speed ratio change rate corresponding to the first limit value, and based on the first limit speed ratio change rate, control the continuously variable transmission to output the first speed ratio corresponding to the first control cycle;

[0026] Determine whether the first speed ratio is equal to the target speed ratio;

[0027] If the first speed ratio is not equal to the target speed ratio, then determine whether the difference between the first limited speed ratio change rate and the target speed ratio change rate is zero;

[0028] If it is determined that the difference between the first restricted speed ratio change rate and the target speed ratio change rate is not zero, then the next control cycle is determined, and the next control cycle is used as the new first control cycle. Then, the process returns to the step of obtaining each first control parameter corresponding to the first control cycle.

[0029] If it is determined that the difference between the first restricted speed ratio change rate and the target speed ratio change rate is zero, then it is determined whether the difference between the first speed ratio and the target speed ratio is greater than a preset first threshold.

[0030] If the difference between the first speed ratio and the target speed ratio is greater than the first threshold, then the next control cycle is determined and the next control cycle is defined as the second control cycle;

[0031] Based on the target speed ratio change rate, the continuously variable transmission is controlled to output a second speed ratio corresponding to the second control cycle;

[0032] Determine whether the difference between the second speed ratio and the target speed ratio is greater than the first threshold.

[0033] If the difference between the second speed ratio and the target speed ratio is greater than the first threshold, then the next control cycle is determined, and the next control cycle is determined as the new second control cycle. Then, the process of controlling the continuously variable transmission to output the second speed ratio corresponding to the second control cycle based on the target speed ratio change rate is returned.

[0034] If the difference between the second speed ratio and the target speed ratio is not greater than the first threshold, then the next control cycle is determined and the next control cycle is defined as the third control cycle;

[0035] Obtain the second control parameters corresponding to the third control cycle;

[0036] Based on each of the second control parameters, a second limit range for the rate of change of the target speed ratio corresponding to the third control cycle is determined;

[0037] Determine a second limiting parameter corresponding to the third control cycle, and based on the second limiting parameter and the second limiting range, determine a second limiting value for the rate of change of the target speed ratio corresponding to the third control cycle;

[0038] Determine the third limit speed ratio change rate corresponding to the third limit value, and based on the third limit speed ratio change rate, control the continuously variable transmission to output the third speed ratio corresponding to the third control cycle;

[0039] Determine whether the third speed ratio is equal to the target speed ratio;

[0040] If the third speed ratio is not equal to the target speed ratio, then the next control cycle is determined, and the next control cycle is set as the new third control cycle. Then, the operation of obtaining each second control parameter corresponding to the third control cycle is returned.

[0041] If the third speed ratio is equal to the target speed ratio, then the speed ratio control of the continuously variable transmission is completed.

[0042] The second aspect of this application discloses a speed ratio control device for a continuously variable transmission (CVT), comprising:

[0043] The acquisition unit is used to acquire the current target speed of the continuously variable transmission (CVT) and, based on the target speed, determine whether the CVT meets the preset speed ratio control conditions.

[0044] The determining unit is used to determine the current target speed ratio of the continuously variable transmission when it is determined that the continuously variable transmission meets the preset speed ratio control conditions;

[0045] An adjustment unit is used to determine the target speed ratio change rate of the target speed ratio, and periodically adjust the change rate of the target speed ratio change rate based on a preset speed ratio limiting strategy, and adjust the speed ratio of the continuously variable transmission according to the adjusted limiting speed ratio change rate until the speed ratio of the continuously variable transmission reaches the target speed ratio.

[0046] Optionally, the acquisition unit in the aforementioned apparatus includes:

[0047] The first acquisition subunit is used to acquire the current throttle opening and vehicle speed of the vehicle to which the continuously variable transmission belongs;

[0048] The first processing subunit is used to process the throttle opening and the vehicle speed of the vehicle to obtain the target speed of the continuously variable transmission.

[0049] Optionally, the acquisition unit in the aforementioned apparatus includes:

[0050] The second acquisition subunit is used to acquire the current input shaft speed of the continuously variable transmission;

[0051] The first determining subunit is used to determine the speed difference between the input shaft speed and the target speed;

[0052] The second determining subunit is used to determine whether the speed difference is greater than or equal to a preset difference.

[0053] The third determining subunit is used to determine that the continuously variable transmission meets the preset speed ratio control conditions when the speed difference is greater than or equal to the preset difference.

[0054] Optionally, the determining unit in the aforementioned apparatus includes:

[0055] The second processing subunit is used to process the target speed and the input shaft speed to obtain the current target speed ratio of the continuously variable transmission.

[0056] Optionally, the adjustment unit in the aforementioned device includes:

[0057] The fourth determining subunit is used to determine the initial control cycle and set the initial control cycle as the first control cycle;

[0058] The third acquisition subunit is used to acquire each of the first control parameters corresponding to the first control cycle;

[0059] The fourth acquisition subunit is used to obtain a first limit range of the rate of change of the target speed ratio corresponding to the first control cycle based on each of the first control parameters.

[0060] The fifth determining subunit is used to determine the first limiting parameter corresponding to the first control cycle, and based on the first limiting parameter and the first limiting range, to determine the first limiting value of the rate of change of the target speed ratio corresponding to the first control cycle;

[0061] The first control subunit is used to determine the first limit speed ratio change rate corresponding to the first limit value, and based on the first limit speed ratio change rate, control the continuously variable transmission to output the first speed ratio corresponding to the first control cycle;

[0062] The first judgment subunit is used to determine whether the first speed ratio is equal to the target speed ratio;

[0063] The sixth determining subunit is used to determine whether the difference between the first limited speed ratio change rate and the target speed ratio change rate is zero if the first speed ratio is not equal to the target speed ratio.

[0064] The seventh determining subunit is used to determine the next control cycle if it is determined that the difference between the first limited speed ratio change rate and the target speed ratio change rate is not zero, and to take the next control cycle as the new first control cycle, and return to the step of obtaining each first control parameter corresponding to the first control cycle.

[0065] The eighth determining subunit is used to determine whether the difference between the first speed ratio and the target speed ratio is greater than a preset first threshold if the difference between the first speed ratio and the target speed ratio is determined to be zero.

[0066] The ninth determining subunit is used to determine the next control cycle if the difference between the first speed ratio and the target speed ratio is greater than the first threshold, and to determine the next control cycle as the second control cycle.

[0067] The second control subunit is used to control the continuously variable transmission to output a second speed ratio corresponding to the second control cycle based on the target speed ratio change rate.

[0068] The second judgment subunit is used to determine whether the difference between the second speed ratio and the target speed ratio is greater than the first threshold.

[0069] The tenth determining subunit is used to determine the next control cycle if the difference between the second speed ratio and the target speed ratio is greater than the first threshold, and to determine the next control cycle as a new second control cycle, and return to the step of controlling the continuously variable transmission to output the second speed ratio corresponding to the second control cycle based on the target speed ratio change rate;

[0070] The eleventh determining subunit is used to determine the next control cycle if the difference between the second speed ratio and the target speed ratio is not greater than the first threshold, and to determine the next control cycle as the third control cycle.

[0071] The fifth acquisition subunit is used to acquire each of the second control parameters corresponding to the third control cycle;

[0072] The twelfth determining subunit is used to determine a second limiting range of the rate of change of the target speed ratio corresponding to the third control cycle based on each of the second control parameters;

[0073] The thirteenth determining subunit is used to determine the second limiting parameter corresponding to the third control cycle, and based on the second limiting parameter and the second limiting range, to determine the second limiting value of the rate of change of the target speed ratio corresponding to the third control cycle;

[0074] The third control subunit is used to determine the third limit speed ratio change rate corresponding to the third limit value, and based on the third limit speed ratio change rate, control the continuously variable transmission to output the third speed ratio corresponding to the third control cycle;

[0075] The third judgment subunit is used to determine whether the third speed ratio is equal to the target speed ratio;

[0076] The fourteenth determining subunit is used to determine the next control cycle if the third speed ratio is not equal to the target speed ratio, and to determine the next control cycle as a new third control cycle, and return to execute the operation of obtaining each second control parameter corresponding to the third control cycle;

[0077] The completion subunit is used to control the speed ratio of the continuously variable transmission if the third speed ratio is equal to the target speed ratio.

[0078] A third aspect of this application discloses a storage medium comprising stored instructions, wherein, when the instructions are executed, the device in which the storage medium is located executes the continuously variable transmission (CVT) speed ratio control method described above.

[0079] The fourth aspect of this application discloses an electronic device, including a memory and one or more instructions, wherein one or more instructions are stored in the memory and configured to be executed by one or more processors as described above for the speed ratio control method of a continuously variable transmission.

[0080] Compared with the prior art, the present invention has the following advantages:

[0081] This invention provides a speed ratio control method, apparatus, storage medium, and electronic device for a continuously variable transmission (CVT). The method includes: acquiring the current target speed of the CVT and determining whether the CVT meets preset speed ratio control conditions based on the target speed; when it is determined that the CVT meets the preset speed ratio control conditions, determining the current target speed ratio of the CVT; determining the target speed ratio change rate, and periodically adjusting the change rate of the target speed ratio change rate based on a preset speed ratio limiting strategy, and adjusting the speed ratio of the CVT according to the adjusted limiting speed ratio change rate until the speed ratio of the CVT reaches the target speed ratio. When it is determined that the CVT meets the speed ratio control conditions, the periodic adjustment of the change rate of the target speed ratio change rate according to the preset speed ratio limiting strategy, and the adjustment of the CVT speed ratio according to the adjusted limiting speed ratio change rate, allows the CVT speed ratio to smoothly switch to the target speed ratio, thereby effectively mitigating system flow fluctuations, delaying CVT aging, and extending CVT lifespan. Attached Figure Description

[0082] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0083] Figure 1 This is an example diagram of a CVT gear shifting system;

[0084] Figure 2 This is a schematic diagram of a CVT master-slave hydraulic cylinder;

[0085] Figure 3 Example graphs showing various vehicle parameters when the speed ratio of a continuously variable transmission (CVT) is controlled using conventional methods.

[0086] Figure 4 A flowchart of a continuously variable transmission (CVT) speed ratio control method provided in an embodiment of the present invention;

[0087] Figure 5 Another flowchart of a continuously variable transmission (CVT) speed ratio control method provided in this embodiment of the invention;

[0088] Figure 6 A flowchart illustrating another method for speed ratio control of a continuously variable transmission (CVT) provided in an embodiment of the present invention;

[0089] Figure 7 Example curves of various indicators of a vehicle after applying the present invention, provided for embodiments of the present invention;

[0090] Figure 8 Example diagrams of various speed ratio curves provided in embodiments of the present invention;

[0091] Figure 9 A schematic diagram of the speed ratio control device for a continuously variable transmission (CVT) provided in an embodiment of the present invention;

[0092] Figure 10 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0093] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0094] In this application, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0095] As a new type of power shift transmission, the continuously variable transmission (CVT) boasts advantages such as driving comfort, low emissions, good fuel economy, and stepless shifting, making it a promising market prospect. In particular, the CVT achieves a dynamic and optimal match between vehicle driving resistance and engine load through continuous changes in the speed ratio, ensuring the engine always operates in its high-efficiency range and maximizing its potential according to the driver's intended operation.

[0096] The traditional continuously variable transmission (CVT) control method is as follows: The target engine speed is determined based on the throttle opening and vehicle speed. The CVT then calculates its target gear ratio based on this target engine speed. Figure 1 The diagram shown illustrates the CVT shifting when controlling the speed ratio of a continuously variable transmission (CVT) using conventional methods. (Reference) Figure 2 The diagram shows the CVT master and slave cylinders. The traditional working condition of the CVT master and slave levers is as follows:

[0097] (1) The driven cylinder determines its pressure based on the torque transmitted by the steel belt and the actual speed ratio, so as to ensure that the steel belt can safely transmit torque, that is, the driven cylinder is responsible for clamping force.

[0098] (2) The driving cylinder determines its pressure based on the target speed ratio and the oil pressure of the driven cylinder to ensure that the actual speed ratio follows the target speed ratio. That is, the driving cylinder is responsible for speed ratio control.

[0099] At a certain vehicle speed, when the driver increases the throttle, the target speed and target speed ratio of the input shaft also increase accordingly, such as... Figure 3The graph shows curves illustrating various vehicle parameters when controlling the gear ratio of a continuously variable transmission (CVT) using traditional methods. As the graph shows, when the gear ratio changes from a near-steady-speed condition to rapid shifting, the overall system flow increases dramatically. The valves of the master and slave cylinders need to adjust from a low-flow equilibrium state to a new high-flow equilibrium state, which takes time. This causes a hydraulic dip (hydraulic depression), resulting in insufficient clamping force and the risk of belt slippage. When the actual speed reaches the target speed, the target gear ratio changes from rapid shifting to slow shifting. At this point, the overall system flow decreases dramatically. The valves of the master and slave cylinders need to adjust from a high-flow equilibrium state to a new low-flow equilibrium state, which also takes time. This causes an overshoot (hydraulic bulge), resulting in excessive clamping force, increased belt stress, accelerated belt fatigue and aging, and a reduced CVT lifespan.

[0100] This invention aims to provide a novel speed ratio control method to solve the problem that hydraulic slippage and hydraulic overshoot caused by the response delay of the hydraulic system when the CVT speed ratio change rate changes drastically, leading to accelerated aging of the CVT and shortened service life.

[0101] This invention provides a speed ratio control method for a continuously variable transmission (CVT), which can be applied to a vehicle control system. This control system consists of a computer terminal or a distributed computing device, such as a microcomputer, a central processor, and other intelligent devices with data processing capabilities.

[0102] Reference Figure 4 The following is a detailed description of the method flow for a continuously variable transmission (CVT) speed ratio control method provided in an embodiment of the present invention:

[0103] S101. Obtain the current target speed of the continuously variable transmission (CVT), and based on the target speed, determine whether the CVT meets the preset speed ratio control conditions.

[0104] Preferably, the continuously variable transmission (CVT) is a steel belt type or a chain type CVT. The specific process for obtaining the current target speed of the CVT is as follows:

[0105] The current throttle opening and vehicle speed of the vehicle to which the continuously variable transmission (CVT) belongs can be obtained. It should be noted that the current throttle opening and vehicle speed of the vehicle can be obtained through a dedicated sensor.

[0106] The throttle opening and vehicle speed of the vehicle are processed to obtain the target speed of the continuously variable transmission (CVT); the target speed is the speed that the CVT should actually reach.

[0107] By processing the current throttle opening and vehicle speed of the vehicle to which the continuously variable transmission (CVT) belongs, the current target speed of the CVT can be obtained.

[0108] Furthermore, the current target speed of the continuously variable transmission (CVT) is determined in real time. Preferably, the current target speed of the CVT changes when the throttle opening of the vehicle changes.

[0109] Reference Figure 5 The flowchart of the method for determining whether a continuously variable transmission (CVT) currently meets the preset speed ratio control conditions is described in detail below:

[0110] S201. Obtain the current input shaft speed of the continuously variable transmission (CVT).

[0111] The current input shaft speed of the continuously variable transmission (CVT) can be obtained using a sensor that acquires the input shaft speed. The current input shaft speed of the CVT is the actual current speed of the CVT.

[0112] S202. Determine the speed difference between the input shaft speed and the target speed.

[0113] The speed difference is an absolute value, meaning it is a positive number; in other words, the speed difference is the absolute value of the difference between the output shaft and the target speed.

[0114] S203. Determine whether the speed difference is greater than or equal to the preset difference; when the speed difference is greater than or equal to the preset difference, execute S204; when the speed difference is not greater than or equal to the preset difference, execute S205.

[0115] The speed difference is compared with the preset difference to determine whether the speed difference is greater than or equal to the preset difference.

[0116] The preset difference value is a pre-set value that can be set according to actual needs. It is usually a reasonable value obtained after analyzing a large amount of data, and the value is positive.

[0117] S204. Determine that the continuously variable transmission (CVT) meets the preset speed ratio control conditions.

[0118] S205. It is determined that the continuously variable transmission does not meet the preset speed ratio control conditions.

[0119] Furthermore, when it is determined that the continuously variable transmission (CVT) meets the preset speed ratio control conditions, the next process can be initiated. When it is determined that the CVT does not meet the preset speed ratio control conditions, a new target speed for the CVT can be obtained, and based on the new target speed, it can be determined again whether the CVT meets the preset speed ratio control conditions.

[0120] It should be noted that when the continuously variable transmission (CVT) meets the preset speed ratio control conditions, it can be determined that the speed ratio of the CVT has changed by a step, and it is necessary to control the actual speed ratio of the CVT to gradually switch to the target speed ratio.

[0121] S102. When it is determined that the continuously variable transmission (CVT) meets the preset speed ratio control conditions, the current target speed ratio of the CVT is determined.

[0122] When determining the target speed ratio of a continuously variable transmission (CVT), it can be determined by the target speed and the input shaft speed. Specifically, the target speed can be divided by the input shaft speed to obtain the current target speed ratio of the CVT.

[0123] S103. Determine the target speed ratio change rate of the target speed ratio, and periodically adjust the change rate of the target speed ratio change rate based on a preset speed ratio limiting strategy, and adjust the speed ratio of the continuously variable transmission according to the adjusted limiting speed ratio change rate until the speed ratio of the continuously variable transmission reaches the target speed ratio.

[0124] In the method provided by this invention, the target rate of change of the target speed ratio can be obtained by taking the first derivative of the speed ratio.

[0125] After obtaining the target speed ratio change rate, it is necessary to periodically adjust the change rate of the target speed ratio based on the speed ratio limiting strategy and the response characteristics of the hydraulic system. Each adjustment of the target speed ratio change rate yields a corresponding limiting speed ratio change rate. The speed ratio of the continuously variable transmission (CVT) is adjusted according to the limiting speed ratio change rate to obtain the speed ratio corresponding to the limiting speed ratio change rate. The speed ratio corresponding to the limiting speed ratio change rate is compared with the target speed ratio. When the speed ratio corresponding to the limiting speed ratio change rate matches the target speed ratio, the adjustment of the target speed ratio change rate can be stopped to complete the control of the CVT speed ratio. When the speed ratio corresponding to the limiting speed ratio change rate does not match the target speed ratio, the adjustment of the target speed ratio change rate continues.

[0126] In the method provided by the embodiments of the present invention, when adjusting the rate of change of the target speed ratio, it can be obtained by taking the second derivative of the speed ratio. By adjusting the rate of change of the target speed ratio, the speed ratio of the continuously variable transmission can be gradually and smoothly switched to the target speed ratio in a curved manner during the process of gradually adjusting the speed ratio to the target speed ratio, ensuring the smoothness of the speed ratio switching process and improving the drivability of the vehicle.

[0127] In the method provided by this invention, the current target speed of the continuously variable transmission (CVT) is obtained, and based on the target speed, it is determined whether the CVT meets a preset speed ratio control condition. When it is determined that the CVT meets the preset speed ratio control condition, the current target speed ratio of the CVT is determined. The target speed ratio change rate is determined, and based on a preset speed ratio limiting strategy, the change rate of the target speed ratio change rate is periodically adjusted. The speed ratio of the CVT is then adjusted according to the adjusted limiting speed ratio change rate until the speed ratio of the CVT reaches the target speed ratio. When it is determined that the CVT meets the speed ratio control condition, the change rate of the target speed ratio change rate is periodically adjusted according to the preset speed ratio limiting strategy, and the speed ratio of the CVT is adjusted according to the adjusted limiting speed ratio change rate. This allows the speed ratio of the CVT to smoothly switch to the target speed ratio, thereby effectively mitigating system flow fluctuations, delaying CVT aging, and extending CVT lifespan.

[0128] The method provided in this embodiment of the invention describes the process of periodically adjusting the rate of change of the target speed ratio and controlling the speed ratio of the continuously variable transmission (CVT) according to the adjusted limit rate of change until the speed ratio of the CVT reaches the target speed ratio. The specific process is described below. Figure 6 As shown, the specific explanation is as follows:

[0129] S301. Determine the initial control period and set the initial control period as the first control period.

[0130] When determining the initial control cycle, it can be determined based on the preset time step. For example, if the time step is 0.01 seconds, then the duration of the initial control cycle is 0.01 seconds.

[0131] The initial control cycle is the first cycle for adjusting the rate of change of the target speed ratio, and also the first cycle for adjusting the speed ratio of the continuously variable transmission.

[0132] S302. Obtain the first control parameters corresponding to the first control cycle.

[0133] The first control parameters include, but are not limited to, the oil temperature of the hydraulic system and the current actual output speed ratio of the continuously variable transmission; furthermore, the first control parameters may also include the current driven cylinder pressure and driving cylinder pressure of the hydraulic system.

[0134] S303. Based on each first control parameter, obtain the first limit range of the rate of change of the target speed ratio corresponding to the first control cycle.

[0135] Based on each of the first control parameters, by performing a derivative operation, the first limit range of the rate of change of the target speed ratio corresponding to the first control cycle can be obtained, where the first limit range is the range within which the rate of change of the target speed ratio can be adjusted.

[0136] S304. Determine the first limiting parameter corresponding to the first control cycle, and based on the first limiting parameter and the first limiting range, determine the first limiting value of the rate of change of the target speed ratio corresponding to the first control cycle.

[0137] It should be noted that when the first control cycle is the initial control cycle, the first limit parameter is empty; when the first control cycle is not the initial control cycle, the first limit parameter is the limit value of the rate of change of the target speed ratio in the previous control cycle; the specific value of the determined first limit value is within the first limit range.

[0138] S305. Determine the first limit speed ratio change rate corresponding to the first limit value, and based on the first limit speed ratio change rate, control the continuously variable transmission output to the first speed ratio corresponding to the first control cycle.

[0139] After determining the first limit value, the first limit speed ratio change rate can be determined based on the first limit value, and the continuously variable transmission (CVT) output can be controlled according to the first limit speed ratio change rate to correspond to the first speed ratio of the first control cycle; wherein, the first speed ratio is the speed ratio output by the CVT within the first control cycle controlled according to the first limit speed ratio change rate. The first speed ratio is the actual output speed ratio of the CVT.

[0140] S306. Determine whether the first speed ratio is equal to the target speed ratio; if it is determined that the first speed ratio is not equal to the target speed ratio, then execute S307; if it is determined that the first speed ratio is equal to the target speed ratio, then execute S321.

[0141] By comparing the first gear ratio with the target gear ratio, it can be determined whether the first gear ratio is equal to the target gear ratio.

[0142] S307. Determine whether the difference between the first limit speed ratio change rate and the target speed ratio change rate is zero; if it is determined that the difference between the first limit speed ratio change rate and the target speed ratio change rate is not zero, then execute S308; if it is determined that the difference between the first limit speed ratio change rate and the target speed ratio change rate is zero, then execute S309.

[0143] S308. Determine the next control cycle, set the next control cycle as the new first control cycle, and return to execute S302.

[0144] The first stage is the process of adjusting the speed ratio of the continuously variable transmission (CVT) based on the first control cycle. In this stage, the rate of change of the target speed ratio can be gradually adjusted so that the rate of change of the CVT can smoothly transition to the target speed ratio in the form of a curve. This allows the CVT speed ratio to be adjusted in a curve, which can reduce flow fluctuations, thus enabling good tracking of hydraulic pressure, delaying CVT aging, and extending the CVT's service life.

[0145] S309. Determine whether the difference between the first speed ratio and the target speed ratio is greater than a preset first threshold; if the difference between the first speed ratio and the target speed ratio is greater than the first threshold, then execute S310; if the difference between the first speed ratio and the target speed ratio is not greater than the first threshold, then execute S314.

[0146] S310. Determine the next control cycle and designate the next control cycle as the second control cycle.

[0147] When the next control cycle is determined as the second control cycle, it indicates that the rate of change of the continuously variable transmission (CVT) speed ratio has entered the constant speed change stage. At this time, the output speed ratio of the CVT can be directly controlled according to the target speed ratio change.

[0148] S311. Based on the target speed ratio change rate, control the output of the continuously variable transmission to the second speed ratio corresponding to the second control cycle.

[0149] The process of adjusting the rate of change of the target speed ratio is the second stage, in which the speed ratio of the continuously variable transmission changes at a steady speed.

[0150] S312. Determine whether the difference between the second speed ratio and the target speed ratio is greater than the first threshold. If the difference between the second speed ratio and the target speed ratio is greater than the first threshold, then execute S313. If the difference between the second speed ratio and the target speed ratio is not greater than the first threshold, then execute S314.

[0151] S313. Determine the next control cycle, set the next control cycle as the new second control cycle, and return to execute S311.

[0152] S314. Determine the next control cycle and designate the next control cycle as the third control cycle.

[0153] It should be noted that when the next control cycle is determined as the third control cycle, the adjustment of the continuously variable transmission (CVT) speed ratio can be determined to enter the third stage. In this stage, by adjusting the rate of change of the target speed ratio, the CVT speed ratio can be smoothly transitioned to the target speed ratio, effectively reducing flow fluctuations, improving the working performance of the CVT, delaying the aging of the CVT, and extending the service life of the CVT.

[0154] It should be noted that when the next control cycle is determined to be the third control cycle, the time for entering the third stage of adjusting the gear ratio of the continuously variable transmission (CVT) has already been determined. At this time, the gear ratio of the CVT has not yet reached the target gear ratio.

[0155] S315. Obtain the second control parameters corresponding to the third control cycle.

[0156] The second control parameters include, but are not limited to, oil temperature, speed ratio response time to the spool valve, driven cylinder pressure and driving cylinder pressure, the current output speed ratio of the continuously variable transmission, and the output speed ratio of the previous cycle.

[0157] S316. Based on each second control parameter, determine the second limit range of the rate of change of the target speed ratio corresponding to the third control cycle.

[0158] Based on each of the second control parameters, a derivative operation is performed to determine the second limit range of the rate of change of the target speed ratio corresponding to the third control cycle.

[0159] S317. Determine the second limiting parameter corresponding to the third control cycle, and based on the second limiting parameter and the second limiting range, determine the second limiting value of the rate of change of the target speed ratio corresponding to the third control cycle.

[0160] The second limiting parameter is the limit value of the rate of change of the speed ratio of the continuously variable transmission in the previous control cycle, and the specific value of the second limiting parameter is within the second limiting range.

[0161] S318. Determine the third limit speed ratio change rate corresponding to the third limit value, and based on the third limit speed ratio change rate, control the continuously variable transmission output to the third speed ratio corresponding to the third control cycle.

[0162] S319. Determine whether the third gear ratio is equal to the target gear ratio; if it is determined that the third gear ratio is not equal to the target gear ratio, then execute S320; if it is determined that the third gear ratio is equal to the target gear ratio, then execute S321.

[0163] S320. Determine the next control cycle, set the next control cycle as the new third control cycle, and return to execute S315.

[0164] S321, Complete the control of the speed ratio of the continuously variable transmission.

[0165] This invention, by taking into account the response delay characteristics of hydraulic systems, increases the adjustment of the rate of change of speed ratio, avoids sudden changes in system flow, ensures normal tracking of actual hydraulic pressure, delays CVT aging, and extends the service life of CVT.

[0166] This invention adjusts the rate of change of the speed ratio in three stages. The first stage is the transition from a steady speed to a rapid speed change. In this stage, the rate of change of the speed ratio is adjusted based on the influence of oil temperature and the response time of the spool valve. The second stage is the steady speed change stage, where the rate of change of the speed ratio is adjusted to 0. In this stage, the speed ratio of the continuously variable transmission (CVT) can be adjusted based on the original rate of change of the speed ratio (i.e., the target rate of change of the speed ratio). The third stage is the transition from a rapid speed change to a steady speed stage. Before entering this stage, the entry time needs to be determined, which is based on the second stage. Furthermore, the entry time into the third stage is the end time of the second stage. After entering the third stage, the rate of change of the speed ratio can be adjusted based on the influence of oil temperature and the delay time of the spool valve, so that the speed ratio of the CVT gradually switches to the target speed ratio.

[0167] For example, Figure 7 The figure shows the change curves of various vehicle parameters after adjusting the gear ratio of a continuously variable transmission (CVT) using this invention. The curves include those for throttle, vehicle speed, input shaft speed, gear ratio, driven cylinder pressure, driving cylinder pressure, and gear ratio change rate. As shown, applying this invention to adjust the gear ratio of the CVT allows the actual gear ratio to smoothly transition to the target gear ratio. It also allows for real-time tracking of the driving and driven cylinder pressures, thus preventing sudden changes in system flow and delaying CVT aging, extending the CVT's lifespan.

[0168] For example, Figure 8 Examples of various speed ratio curves are shown, including speed ratio curves that adjust the speed ratio of a continuously variable transmission (CVT) using different control methods. The figures include the original target speed ratio curve, the target speed ratio curve after limiting the rate of change of speed ratio, and the target speed ratio curve after limiting the change of the rate of change of speed ratio.

[0169] The original target speed ratio curve does not pass through the speed ratio curve that limits the rate of change of speed ratio. As can be seen from the curve, the speed ratio of the continuously variable transmission directly switches to the speed ratio with a large difference, resulting in a speed ratio step, which can easily cause sudden changes in the flow of the system.

[0170] The target curve after limiting the rate of change of the gear ratio is the gear ratio curve after limiting the rate of change of the gear ratio. As can be seen from the curve, the continuously variable transmission adjusts the gear ratio according to the limited rate of change, so that the gear ratio gradually switches to the target curve. The limited rate of change is the rate of change of the gear ratio, which can be obtained by differentiating the original target gear ratio. Although limiting the rate of change can make the gear ratio of the continuously variable transmission gradually switch to the target curve, as can be seen from the curve, there are still abrupt changes from the beginning of the adjustment to the point where the target gear ratio is reached.

[0171] The target speed ratio curve after limiting the rate of change of the speed ratio is the derivative of the target speed ratio curve after limiting the rate of change of the speed ratio. That is, the target speed ratio curve after limiting the rate of change of the speed ratio is the curve obtained by taking the second derivative of the original target speed ratio curve. As can be seen from the curve, after limiting the rate of change of the speed ratio, the continuously variable transmission (CVT) switches to the target speed ratio in a curved manner, thus achieving a smooth transition to the target curve and mitigating flow fluctuations. The current slope k1 in the figure can be interpreted as the rate of change of the target speed ratio after limiting the rate of change of the speed ratio. ), can also be understood as the rate of change of the speed ratio obtained based on the rate of change of the limit speed ratio; the final slope k0 can be understood as the target speed ratio rate of change, or as the final speed ratio rate of change when reaching the target speed ratio. ), , The target speed ratio; The speed ratio is obtained based on the limited rate of change of the speed ratio.

[0172] It should be noted that the rate of change of the constraint in the figure is the rate of change of the target speed ratio, where, This represents the rate of change of the speed ratio, which can also be understood as the target rate of change of the speed ratio. The rate of change of the speed ratio is obtained by taking the first derivative of the steel belt speed ratio. This refers to the speed ratio of the steel belt.

[0173] ;

[0174] in, The change over one period of time, i.e. Time and The time difference at any given moment is the amount of time change over one cycle; The change in the steel belt speed ratio over one cycle, i.e. Speed ​​ratio at each time point ( )and Speed ​​ratio at each time point ( The difference between ); therefore, When the speed ratio changes Within a certain range, when the period is fixed, the variable range of the rate of change of the speed ratio at a certain moment depends on the speed ratio value and the range of the rate of change of the speed ratio at the previous moment.

[0175] Here, the rate of change of the limiting rate of change can be understood as the rate of change of the limiting target speed ratio. ,in, This represents the rate of change of the target speed ratio. Furthermore, the rate of change of the target speed ratio is obtained by taking the second derivative with respect to the speed ratio of the steel belt. This represents the change in the rate of change of the steel belt speed ratio over one cycle, i.e. Time to Rate of change of speed ratio during the process at time step and Time to Rate of change of speed ratio during the process at time step The difference; Time and The time difference between moments is one period. , Time and The time difference between moments is also a period. ;therefore, When the rate of change of the target speed ratio Within a certain range, when the period is fixed, the variable range of the speed ratio at a certain moment depends on the speed ratio value of the previous period, the speed ratio value of the period before that, and the range of the change rate of the speed ratio.

[0176] This invention fully considers the response characteristics of the hydraulic system, ensuring good tracking of the actual hydraulic pressure during gear ratio changes, avoiding actual hydraulic pressure slippage and overshoot, ensuring real-time clamping of the steel belt, and improving the fatigue life of the steel belt. The rate of change of the actual rotational speed is equivalent to the magnitude of the moment of inertia. After applying this invention, the switching of the rate of change of the actual rotational speed becomes smoother, that is, the change of the moment of inertia is also smoother, and thus the change of the driving force at the wheel end is also smoother, ensuring smoothness during gear ratio changes and improving the overall drivability of the vehicle.

[0177] and Figure 4 Corresponding to the method shown, this embodiment of the invention provides a speed ratio control device for a continuously variable transmission (CVT), used to support... Figure 4 The method shown can be applied in real life. The device provided in this embodiment of the invention can be installed in the vehicle control system. The structural schematic diagram of the device is shown below. Figure 9 As shown, the specific explanation is as follows:

[0178] The acquisition unit 401 is used to acquire the current target speed of the continuously variable transmission (CVT) and determine whether the CVT meets the preset speed ratio control conditions based on the target speed.

[0179] The determining unit 402 is used to determine the current target speed ratio of the continuously variable transmission when it is determined that the continuously variable transmission meets the preset speed ratio control conditions;

[0180] The adjustment unit 403 is used to determine the target speed ratio change rate of the target speed ratio, and periodically adjust the change rate of the target speed ratio change rate based on a preset speed ratio limiting strategy, and adjust the speed ratio of the continuously variable transmission according to the limited speed ratio change rate obtained after adjustment, until the speed ratio of the continuously variable transmission reaches the target speed ratio.

[0181] In the apparatus provided by this invention, the current target speed of the continuously variable transmission (CVT) is acquired, and based on the target speed, it is determined whether the CVT meets preset speed ratio control conditions. When it is determined that the CVT meets the preset speed ratio control conditions, the current target speed ratio of the CVT is determined. The target speed ratio change rate is determined, and based on a preset speed ratio limiting strategy, the change rate of the target speed ratio change rate is periodically adjusted. The speed ratio of the CVT is then adjusted according to the adjusted limiting speed ratio change rate until the speed ratio of the CVT reaches the target speed ratio. When it is determined that the CVT meets the speed ratio control conditions, the change rate of the target speed ratio change rate is periodically adjusted according to the preset speed ratio limiting strategy, and the speed ratio of the CVT is adjusted according to the adjusted limiting speed ratio change rate. This allows the speed ratio of the CVT to smoothly switch to the target speed ratio, thereby effectively mitigating system flow fluctuations, delaying CVT aging, and extending CVT lifespan.

[0182] In the apparatus provided in this embodiment of the invention, the acquisition unit 401 can be configured as follows:

[0183] The first acquisition subunit is used to acquire the current throttle opening and vehicle speed of the vehicle to which the continuously variable transmission belongs;

[0184] The first processing subunit is used to process the throttle opening and the vehicle speed of the vehicle to obtain the target speed of the continuously variable transmission.

[0185] In the apparatus provided in this embodiment of the invention, the acquisition unit 401 can be configured as follows:

[0186] The second acquisition subunit is used to acquire the current input shaft speed of the continuously variable transmission;

[0187] The first determining subunit is used to determine the speed difference between the input shaft speed and the target speed;

[0188] The second determining subunit is used to determine whether the speed difference is greater than or equal to a preset difference.

[0189] The third determining subunit is used to determine that the continuously variable transmission meets the preset speed ratio control conditions when the speed difference is greater than or equal to the preset difference.

[0190] In the apparatus provided in this embodiment of the invention, the determining unit 402 can be configured as follows:

[0191] The second processing subunit is used to process the target speed and the input shaft speed to obtain the current target speed ratio of the continuously variable transmission.

[0192] In the apparatus provided in this embodiment of the invention, the adjustment unit 403 can be configured as follows:

[0193] The fourth determining subunit is used to determine the initial control cycle and set the initial control cycle as the first control cycle;

[0194] The third acquisition subunit is used to acquire each of the first control parameters corresponding to the first control cycle;

[0195] The fourth acquisition subunit is used to obtain a first limit range of the rate of change of the target speed ratio corresponding to the first control cycle based on each of the first control parameters.

[0196] The fifth determining subunit is used to determine the first limiting parameter corresponding to the first control cycle, and based on the first limiting parameter and the first limiting range, to determine the first limiting value of the rate of change of the target speed ratio corresponding to the first control cycle;

[0197] The first control subunit is used to determine the first limit speed ratio change rate corresponding to the first limit value, and based on the first limit speed ratio change rate, control the continuously variable transmission to output the first speed ratio corresponding to the first control cycle;

[0198] The first judgment subunit is used to determine whether the first speed ratio is equal to the target speed ratio;

[0199] The sixth determining subunit is used to determine whether the difference between the first limited speed ratio change rate and the target speed ratio change rate is zero if the first speed ratio is not equal to the target speed ratio.

[0200] The seventh determining subunit is used to determine the next control cycle if it is determined that the difference between the first limited speed ratio change rate and the target speed ratio change rate is not zero, and to take the next control cycle as the new first control cycle, and return to the step of obtaining each first control parameter corresponding to the first control cycle.

[0201] The eighth determining subunit is used to determine whether the difference between the first speed ratio and the target speed ratio is greater than a preset first threshold if the difference between the first speed ratio and the target speed ratio is determined to be zero.

[0202] The ninth determining subunit is used to determine the next control cycle if the difference between the first speed ratio and the target speed ratio is greater than the first threshold, and to determine the next control cycle as the second control cycle.

[0203] The second control subunit is used to control the continuously variable transmission to output a second speed ratio corresponding to the second control cycle based on the target speed ratio change rate.

[0204] The second judgment subunit is used to determine whether the difference between the second speed ratio and the target speed ratio is greater than the first threshold.

[0205] The tenth determining subunit is used to determine the next control cycle if the difference between the second speed ratio and the target speed ratio is greater than the first threshold, and to determine the next control cycle as a new second control cycle, and return to the step of controlling the continuously variable transmission to output the second speed ratio corresponding to the second control cycle based on the target speed ratio change rate;

[0206] The eleventh determining subunit is used to determine the next control cycle if the difference between the second speed ratio and the target speed ratio is not greater than the first threshold, and to determine the next control cycle as the third control cycle.

[0207] The fifth acquisition subunit is used to acquire each of the second control parameters corresponding to the third control cycle;

[0208] The twelfth determining subunit is used to determine a second limiting range of the rate of change of the target speed ratio corresponding to the third control cycle based on each of the second control parameters;

[0209] The thirteenth determining subunit is used to determine the second limiting parameter corresponding to the third control cycle, and based on the second limiting parameter and the second limiting range, to determine the second limiting value of the rate of change of the target speed ratio corresponding to the third control cycle;

[0210] The third control subunit is used to determine the third limit speed ratio change rate corresponding to the third limit value, and based on the third limit speed ratio change rate, control the continuously variable transmission to output the third speed ratio corresponding to the third control cycle;

[0211] The third judgment subunit is used to determine whether the third speed ratio is equal to the target speed ratio;

[0212] The fourteenth determining subunit is used to determine the next control cycle if the third speed ratio is not equal to the target speed ratio, and to determine the next control cycle as a new third control cycle, and return to execute the operation of obtaining each second control parameter corresponding to the third control cycle;

[0213] The completion subunit is used to control the speed ratio of the continuously variable transmission if the third speed ratio is equal to the target speed ratio.

[0214] This invention also provides a storage medium, which includes stored instructions, wherein when the instructions are executed, the device containing the storage medium is controlled to perform the speed ratio control method of the continuously variable transmission described above.

[0215] This invention also provides an electronic device, the structural schematic of which is shown below. Figure 10 As shown, it specifically includes a memory 601 and one or more instructions 602, wherein one or more instructions 602 are stored in the memory 601 and configured to be executed by one or more processors 603 in the above-described continuously variable transmission speed ratio control method.

[0216] The specific implementation processes and derivative methods of the above embodiments are all within the protection scope of this invention.

[0217] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple, and relevant parts can be referred to the descriptions in the method embodiments. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0218] 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 implementations should not be considered beyond the scope of this invention.

[0219] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. 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 the invention. Therefore, the invention 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 speed ratio control method of a continuously variable transmission, characterized by, The method comprises: acquiring a current target speed of the continuously variable transmission, and determining whether the continuously variable transmission meets a preset speed ratio control condition based on the target speed; when it is determined that the continuously variable transmission meets the preset speed ratio control condition, determining a current target speed ratio of the continuously variable transmission; determining a target speed ratio change rate of the target speed ratio, periodically adjusting a change rate of the target speed ratio change rate based on a preset speed ratio limiting strategy, and adjusting the speed ratio of the continuously variable transmission according to a limited speed ratio change rate obtained after the adjustment until the speed ratio of the continuously variable transmission reaches the target speed ratio; wherein the periodically adjusting of the change rate of the target speed ratio change rate based on the preset speed ratio limiting strategy and the adjusting of the speed ratio of the continuously variable transmission according to the limited speed ratio change rate until the speed ratio of the continuously variable transmission reaches the target speed ratio comprises: determining an initial control period and determining the initial control period as a first control period; acquiring each first control parameter corresponding to the first control period; based on each first control parameter, obtaining a first limiting range of a change rate of a target speed ratio change rate corresponding to the first control period; determining a first limiting parameter corresponding to the first control period, and determining a first limiting value of a change rate of a target speed ratio change rate corresponding to the first control period based on the first limiting parameter and the first limiting range; determining a first limited speed ratio change rate corresponding to the first limiting value, and controlling the continuously variable transmission to output a first speed ratio corresponding to the first control period based on the first limited speed ratio change rate; determining whether the first speed ratio is equal to the target speed ratio; if the first speed ratio is not equal to the target speed ratio, determining whether a difference between the first limited speed ratio change rate and the target speed ratio change rate is zero; if it is determined that the difference between the first limited speed ratio change rate and the target speed ratio change rate is not zero, determining a next control period and taking the next control period as a new first control period, and returning to execute the step of acquiring each first control parameter corresponding to the first control period; if it is determined that the difference between the first limited speed ratio change rate and the target speed ratio change rate is zero, determining whether a difference between the first speed ratio and the target speed ratio is greater than a preset first threshold value; if the difference between the first speed ratio and the target speed ratio is greater than the first threshold value, determining a next control period and taking the next control period as a second control period; controlling the continuously variable transmission to output a second speed ratio corresponding to the second control period based on the target speed ratio change rate; determining whether a difference between the second speed ratio and the target speed ratio is greater than the first threshold value; if the difference between the second speed ratio and the target speed ratio is greater than the first threshold value, determining a next control period, taking the next control period as a new second control period, and returning to execute the step of controlling the continuously variable transmission to output a second speed ratio corresponding to the second control period based on the target speed ratio change rate; If the difference between the second speed ratio and the target speed ratio is not greater than the first threshold value, a next control period is determined, and the next control period is determined as a third control period; obtaining each second control parameter corresponding to the third control period; determining a second limit range of a change rate of the target speed ratio change rate corresponding to the third control period based on each second control parameter; determining a second limit parameter corresponding to the third control period, and determining a second limit value of the change rate of the target speed ratio change rate corresponding to the third control period based on the second limit parameter and the second limit range; determining a third limit speed ratio change rate corresponding to the second limit value, and controlling the continuously variable transmission to output a third speed ratio corresponding to the third control period based on the third limit speed ratio change rate; determining whether the third speed ratio is equal to the target speed ratio; If the third speed ratio is not equal to the target speed ratio, a next control period is determined, and the next control period is determined as a new third control period, and the operation of obtaining each second control parameter corresponding to the third control period is executed again; If the third speed ratio is equal to the target speed ratio, the control of the speed ratio of the continuously variable transmission is completed.

2. The method of claim 1, wherein, The obtaining of the current target rotating speed of the continuously variable transmission comprises: obtaining a current accelerator opening degree and a vehicle speed of a vehicle to which the continuously variable transmission belongs; processing the accelerator opening degree and the vehicle speed of the vehicle to obtain the target rotating speed of the continuously variable transmission.

3. The method of claim 1, wherein, The determining of whether the continuously variable transmission satisfies a preset speed ratio control condition based on the target rotating speed comprises: obtaining a current input shaft rotating speed of the continuously variable transmission; determining a rotating speed difference between the input shaft rotating speed and the target rotating speed; determining whether the rotating speed difference is greater than or equal to a preset difference value; when the rotating speed difference is greater than or equal to the preset difference value, determining that the continuously variable transmission satisfies the preset speed ratio control condition.

4. The method of claim 3, wherein, The determining of the current target speed ratio of the continuously variable transmission comprises: processing the target rotating speed and the input shaft rotating speed to obtain the current target speed ratio of the continuously variable transmission.

5. A speed ratio control device for a continuously variable transmission, characterized by comprising: The method comprises: an obtaining unit, configured to obtain a current target rotating speed of a continuously variable transmission, and determine whether the continuously variable transmission satisfies a preset speed ratio control condition based on the target rotating speed; a determining unit, configured to, when it is determined that the continuously variable transmission satisfies the preset speed ratio control condition, determine a current target speed ratio of the continuously variable transmission; an adjusting unit, configured to determine a target speed ratio change rate of the target speed ratio, periodically adjust a change rate of the target speed ratio change rate based on a preset speed ratio limit strategy, and adjust a speed ratio of the continuously variable transmission according to a limit speed ratio change rate obtained after the adjustment, until the speed ratio of the continuously variable transmission reaches the target speed ratio; wherein the adjusting unit comprises: a fourth determining subunit, configured to determine an initial control period, and determine the initial control period as a first control period; a third obtaining subunit, configured to obtain each first control parameter corresponding to the first control period; the fourth obtaining sub-unit is configured to obtain a first limit range of a rate of change of the target speed ratio change rate corresponding to the first control period based on the first control parameters; the fifth determining sub-unit is configured to determine a first limit parameter corresponding to the first control period, and determine a first limit value of the rate of change of the target speed ratio change rate corresponding to the first control period based on the first limit parameter and the first limit range; the first control sub-unit is configured to determine a first limit speed ratio change rate corresponding to the first limit value, and control the continuously variable transmission to output a first speed ratio corresponding to the first control period based on the first limit speed ratio change rate; the first judging sub-unit is configured to judge whether the first speed ratio is equal to the target speed ratio; the sixth determining sub-unit is configured to determine whether a difference between the first limit speed ratio change rate and the target speed ratio change rate is zero if the first speed ratio is not equal to the target speed ratio; the seventh determining sub-unit is configured to determine a next control period and take the next control period as a new first control period, and return to execute the step of obtaining the first control parameters corresponding to the first control period if it is determined that the difference between the first limit speed ratio change rate and the target speed ratio change rate is not zero; the eighth determining sub-unit is configured to determine whether a difference between the first speed ratio and the target speed ratio is greater than a preset first threshold value if it is determined that the difference between the first limit speed ratio change rate and the target speed ratio change rate is zero; the ninth determining sub-unit is configured to determine a next control period and take the next control period as a second control period if the difference between the first speed ratio and the target speed ratio is greater than the first threshold value; the second control sub-unit is configured to control the continuously variable transmission to output a second speed ratio corresponding to the second control period based on the target speed ratio change rate; the second judging sub-unit is configured to judge whether the difference between the second speed ratio and the target speed ratio is greater than the first threshold value; the tenth determining sub-unit is configured to determine a next control period and take the next control period as a new second control period, and return to execute the step of controlling the continuously variable transmission to output the second speed ratio corresponding to the second control period based on the target speed ratio change rate if the difference between the second speed ratio and the target speed ratio is greater than the first threshold value; the eleventh determining sub-unit is configured to determine a next control period and take the next control period as a third control period if the difference between the second speed ratio and the target speed ratio is not greater than the first threshold value; the fifth obtaining sub-unit is configured to obtain second control parameters corresponding to the third control period; the twelfth determining sub-unit is configured to determine a second limit range of a rate of change of the target speed ratio change rate corresponding to the third control period based on the second control parameters; the thirteenth determining sub-unit is configured to determine a second limit parameter corresponding to the third control period, and determine a second limit value of the rate of change of the target speed ratio change rate corresponding to the third control period based on the second limit parameter and the second limit range; The third control subunit is configured to determine a third limit ratio change rate corresponding to the second limit value, and control the continuously variable transmission to output a third ratio corresponding to the third control period based on the third limit ratio change rate. The third determination subunit is configured to determine whether the third ratio is equal to the target ratio. The fourteenth determination subunit is configured to, if the third ratio is not equal to the target ratio, determine a next control period, determine the next control period as a new third control period, and return to perform the operation of obtaining each second control parameter corresponding to the third control period. The completion subunit is configured to, if the third ratio is equal to the target ratio, complete the control of the ratio of the continuously variable transmission.

6. The apparatus of claim 5, wherein, The obtaining unit comprises: The first obtaining subunit is configured to obtain a current accelerator opening degree and a vehicle speed of a vehicle to which the continuously variable transmission belongs. The first processing subunit is configured to process the accelerator opening degree and the vehicle speed of the vehicle to obtain a target rotational speed of the continuously variable transmission.

7. The apparatus of claim 5, wherein, The obtaining unit comprises: The second obtaining subunit is configured to obtain a current input shaft rotational speed of the continuously variable transmission. The first determination subunit is configured to determine a rotational speed difference between the input shaft rotational speed and the target rotational speed. The second determination subunit is configured to determine whether the rotational speed difference is greater than or equal to a preset difference value. The third determination subunit is configured to, if the rotational speed difference is greater than or equal to the preset difference value, determine that the continuously variable transmission satisfies a preset ratio control condition.

8. A storage medium, characterized by The storage medium comprises stored instructions, wherein the instructions, when executed, control a device in which the storage medium is located to perform the ratio control method of the continuously variable transmission according to any one of claims 1 to 4.

9. An electronic device, comprising: The computer program product comprises a memory and one or more instructions, wherein the one or more instructions are stored in the memory and configured to be executed by one or more processors to perform the ratio control method of the continuously variable transmission according to any one of claims 1 to 4.

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