阅读说明：本技术 变速箱保护方法和车辆 (Gearbox protection method and vehicle ) 是由 陈才 卜健 蔡铖翔 东永启 李昌波 于 2021-07-30 设计创作，主要内容包括：本发明提出一种变速箱保护方法和车辆,方法包括：获取后车轮加速度和前车轮加速度；根据后车轮加速度与零的比较结果选择车辆工况所在坐标轴的象限,坐标轴的横坐标为后车轮加速度标定值,纵坐标为前车轮加速度标定值,坐标轴的象限内设有不同车辆工况对应的加速度标定曲线；在多个加速度标定曲线上分别找到与后车轮加速度相等的后车轮加速度标定值对应的前车轮加速度标定值；将前车轮加速度分别与不同加速度标定曲线对应的前车轮加速度标定值做差得到多个差值。本发明解决了现有技术中当轮速降低幅度过大,直接脱档并提示变速箱发生故障的方式进行解决所造成的车辆走行过程中动力中断,影响车辆行驶安全的技术问题。(The invention provides a gearbox protection method and a vehicle, wherein the method comprises the following steps: acquiring the acceleration of a rear wheel and the acceleration of a front wheel; selecting a quadrant of a coordinate axis where the vehicle working condition is located according to a comparison result of the acceleration of the rear wheel and zero, wherein the abscissa of the coordinate axis is a rear wheel acceleration calibration value, the ordinate is a front wheel acceleration calibration value, and acceleration calibration curves corresponding to different vehicle working conditions are arranged in the quadrant of the coordinate axis; respectively finding front wheel acceleration calibration values corresponding to rear wheel acceleration calibration values equal to the rear wheel acceleration on the acceleration calibration curves; and respectively differentiating the acceleration of the front wheel with the acceleration calibration values of the front wheel corresponding to different acceleration calibration curves to obtain a plurality of differential values. The invention solves the technical problems that in the prior art, when the wheel speed is reduced by too large amplitude, the power is interrupted in the running process of the vehicle and the running safety of the vehicle is influenced in a mode of directly disengaging and prompting the fault of a gearbox.)

1. A transmission protection method, comprising:

acquiring the acceleration of a rear wheel and the acceleration of a front wheel;

selecting a quadrant of a coordinate axis where the vehicle working condition is located according to a comparison result of the acceleration of the rear wheel and zero, wherein the abscissa of the coordinate axis is a rear wheel acceleration calibration value, the ordinate is a front wheel acceleration calibration value, and acceleration calibration curves corresponding to different vehicle working conditions are arranged in the quadrant of the coordinate axis;

respectively finding front wheel acceleration calibration values corresponding to rear wheel acceleration calibration values equal to the rear wheel acceleration on the acceleration calibration curves;

respectively differentiating the acceleration of the front wheel with the acceleration calibration values of the front wheel corresponding to different acceleration calibration curves to obtain a plurality of differential values;

obtaining the working condition type of the vehicle according to the comparison result of the plurality of difference values and zero;

and adjusting the protection strategy of the gearbox according to the type of the working condition.

2. The transmission protection method of claim 1,

the acceleration calibration curve comprises: the calibration curve calibration method comprises the following steps that a first calibration curve and a second calibration curve which are positioned in a first quadrant, and a third calibration curve and a fourth calibration curve which are positioned in a third quadrant are obtained;

the first calibration curve and the second calibration curve correspond to a low-attachment high-attachment working condition;

the third calibration curve and the fourth calibration curve correspond to the emergency braking working condition.

3. The transmission protection method according to claim 2,

if the acceleration of the rear wheel is larger than zero, the difference between the acceleration of the front wheel and the acceleration calibration value of the front wheel corresponding to the first calibration curve is smaller than zero, and the difference between the acceleration of the front wheel and the acceleration calibration value of the front wheel corresponding to the second calibration curve is larger than zero, the working condition type of the vehicle is judged to be a first working condition, and the first working condition is as follows: the vehicle is in a driving state and the degree of slip of the front wheels is low.

4. The transmission protection method of claim 3,

the protection strategy for adjusting the gearbox according to the working condition type comprises the following steps: and if the working condition type of the vehicle is the first working condition, the oil pressure of the driving pulley and the driven pulley of the gearbox is increased.

5. The transmission protection method of claim 1,

if the acceleration of the rear wheel is larger than zero, and the difference between the acceleration of the front wheel and the calibrated value of the acceleration of the front wheel corresponding to the first calibrated curve is larger than or equal to zero, judging that the type of the working condition of the vehicle is a second working condition, wherein the second working condition is as follows: the vehicle is in a driving state and the level of slip of the front wheels is high.

6. The transmission protection method according to claim 5,

the protection strategy for adjusting the gearbox according to the working condition type comprises the following steps: and if the type of the working condition of the vehicle is the second working condition, the oil pressure of the driving belt wheel and the driven belt wheel of the gearbox is increased, and the hydraulic torque converter is opened at the same time.

7. The transmission protection method of claim 1,

if the acceleration of the rear wheel is smaller than zero, the difference between the absolute value of the acceleration of the front wheel and the absolute value of the acceleration calibration value of the front wheel corresponding to the third calibration curve is larger than or equal to zero, and the difference between the absolute value of the acceleration of the front wheel and the absolute value of the acceleration calibration value of the front wheel corresponding to the fourth calibration curve is smaller than zero, the type of the working condition of the vehicle is judged to be a third working condition, and the third working condition is that: the vehicle is in a braking state and the degree of braking of the front wheels is low.

8. The transmission protection method according to claim 7,

the protection strategy for adjusting the gearbox according to the working condition type comprises the following steps: and if the type of the working condition of the vehicle is the third working condition, the hydraulic torque converter is opened.

9. The transmission protection method of claim 1,

if the acceleration of the rear wheel is smaller than zero, and the difference between the absolute value of the acceleration of the front wheel and the absolute value of the calibration value of the acceleration of the front wheel corresponding to the fourth calibration curve is larger than or equal to zero, judging that the type of the working condition of the vehicle is a fourth working condition, wherein the fourth working condition is as follows: the vehicle is in a braking state and the level of braking of the front wheels is high.

10. The transmission protection method according to claim 9,

the protection strategy for adjusting the gearbox according to the working condition type comprises the following steps: and if the type of the working condition of the vehicle is the fourth working condition, opening the hydraulic torque converter and opening the forward gear clutch.

11. A vehicle comprising a transmission protection method according to any one of claims 1 to 10.

Technical Field

The invention relates to the field of vehicles, in particular to a gearbox protection method and a vehicle.

Background

When the front wheel of the vehicle suddenly drives from a low-friction road surface to a high-friction road surface in the running process of the vehicle, the rotating speed of the front wheel of the vehicle is suddenly reduced, so that large impact is caused to a gearbox; similarly, if emergency braking is performed when the vehicle is running at a high speed, the wheel speed of the front wheel is suddenly reduced, and large impact is also generated on the transmission, so that the service life of the transmission is shortened.

In the prior art, aiming at the condition that the gearbox is damaged due to the fact that the wheel speed of a front wheel is suddenly reduced, the problem is generally solved by directly jumping the neutral position of the gear, and the gearbox is prompted to break down; however, the mode easily causes power interruption in the running process of the vehicle, and the running safety of the vehicle is affected. Therefore, a completely new transmission protection method for the situation needs to be provided.

Disclosure of Invention

Based on the problems, the invention provides a gearbox protection method and a vehicle, and solves the technical problems that in the prior art, when the wheel speed is reduced too much, the gear is directly disengaged and the gearbox is prompted to break down, so that the problem that the driving safety of the vehicle is influenced due to the fact that the power is interrupted in the vehicle running process is solved, and the driving performance of the vehicle and the safety of the gearbox are difficult to balance by the single protection action. The transmission protection method provided by the invention can protect a front-mounted front-drive system of a vehicle, so that when a front wheel of the vehicle suddenly drives from a low-friction road surface to a high-friction road surface and the vehicle is emergently braked when running at a high speed, the damage to the transmission is reduced, a steel belt for transmitting power in the transmission is protected, the transmission is not broken, and the service life of the transmission is prolonged.

The invention provides a gearbox protection method, which comprises the following steps:

acquiring the acceleration of a rear wheel and the acceleration of a front wheel;

selecting a quadrant of a coordinate axis where the vehicle working condition is located according to a comparison result of the acceleration of the rear wheel and zero, wherein the abscissa of the coordinate axis is a rear wheel acceleration calibration value, the ordinate is a front wheel acceleration calibration value, and acceleration calibration curves corresponding to different vehicle working conditions are arranged in the quadrant of the coordinate axis;

respectively finding front wheel acceleration calibration values corresponding to rear wheel acceleration calibration values equal to the rear wheel acceleration on the acceleration calibration curves;

respectively differentiating the acceleration of the front wheel with the acceleration calibration values of the front wheel corresponding to different acceleration calibration curves to obtain a plurality of differential values;

obtaining the working condition type of the vehicle according to the comparison result of the plurality of difference values and zero;

and adjusting the protection strategy of the gearbox according to the type of the working condition.

In addition, the acceleration calibration curve includes: the calibration curve calibration method comprises the following steps that a first calibration curve and a second calibration curve which are positioned in a first quadrant, and a third calibration curve and a fourth calibration curve which are positioned in a third quadrant are obtained;

the first calibration curve and the second calibration curve correspond to a low-attachment high-attachment working condition;

the third calibration curve and the fourth calibration curve correspond to the emergency braking working condition.

In addition, if the acceleration of the rear wheel is greater than zero, and the difference between the acceleration of the front wheel and the calibrated value of the acceleration of the front wheel corresponding to the first calibrated curve is less than zero, and the difference between the acceleration of the front wheel and the calibrated value of the acceleration of the front wheel corresponding to the second calibrated curve is greater than zero, it is determined that the type of the working condition of the vehicle is a first working condition, and the first working condition is: the vehicle is in a driving state and the degree of slip of the front wheels is low.

In addition, the protection strategy for adjusting the gearbox according to the working condition type comprises the following steps: and if the working condition type of the vehicle is the first working condition, the oil pressure of the driving pulley and the driven pulley of the gearbox is increased.

In addition, if the acceleration of the rear wheel is greater than zero, and the difference between the acceleration of the front wheel and the calibrated value of the acceleration of the front wheel corresponding to the first calibrated curve is greater than or equal to zero, the type of the working condition of the vehicle is judged to be a second working condition, and the second working condition is as follows: the vehicle is in a driving state and the level of slip of the front wheels is high.

In addition, the protection strategy for adjusting the gearbox according to the working condition type comprises the following steps: and if the type of the working condition of the vehicle is the second working condition, the oil pressure of the driving belt wheel and the driven belt wheel of the gearbox is increased, and the hydraulic torque converter is opened at the same time.

In addition, if the acceleration of the rear wheel is less than zero, the difference between the absolute value of the acceleration of the front wheel and the absolute value of the calibration value of the acceleration of the front wheel corresponding to the third calibration curve is greater than or equal to zero, and the difference between the absolute value of the acceleration of the front wheel and the absolute value of the calibration value of the acceleration of the front wheel corresponding to the fourth calibration curve is less than zero, it is determined that the type of the working condition of the vehicle is a third working condition, and the third working condition is: the vehicle is in a braking state and the degree of braking of the front wheels is low.

In addition, the protection strategy for adjusting the gearbox according to the working condition type comprises the following steps: and if the type of the working condition of the vehicle is the third working condition, the hydraulic torque converter is opened.

In addition, if the acceleration of the rear wheel is less than zero, and the difference between the absolute value of the acceleration of the front wheel and the absolute value of the calibration value of the acceleration of the front wheel corresponding to the fourth calibration curve is greater than or equal to zero, it is determined that the type of the working condition of the vehicle is a fourth working condition, and the fourth working condition is: the vehicle is in a braking state and the level of braking of the front wheels is high.

In addition, the protection strategy for adjusting the gearbox according to the working condition type comprises the following steps: and if the type of the working condition of the vehicle is the fourth working condition, opening the hydraulic torque converter and opening the forward gear clutch.

The invention also provides a vehicle comprising the gearbox protection method.

Through adopting above-mentioned technical scheme, have following beneficial effect:

the invention solves the technical problems that in the prior art, when the wheel speed is reduced by too large amplitude, the direct gear-disengaging and the gear-box failure prompting mode are adopted to solve the problems that the power interruption in the vehicle running process influences the vehicle running safety and the single protection action is difficult to balance the vehicle driving performance and the gear-box safety. The transmission protection method provided by the invention can protect a front-mounted front-drive system of a vehicle, so that when a front wheel of the vehicle suddenly drives from a low-friction road surface to a high-friction road surface and the vehicle is emergently braked when running at a high speed, the damage to the transmission is reduced, a steel belt for transmitting power in the transmission is protected, the transmission is not broken, and the service life of the transmission is prolonged.

Drawings

FIG. 1 is a flow chart of a transmission protection method provided by one embodiment of the present invention;

FIG. 2 is a schematic diagram of the operation of a transmission provided in accordance with an embodiment of the present invention;

FIG. 3 is a diagram of a transmission provided in accordance with one embodiment of the present invention in connection with other components;

FIG. 4 is a schematic illustration of a vehicle operating condition provided by one embodiment of the present invention;

FIG. 5 is a schematic illustration of a vehicle operating condition provided by one embodiment of the present invention;

FIG. 6 is a schematic diagram of an acceleration calibration curve provided by an embodiment of the present invention;

FIG. 7 is a flow chart of a transmission protection method provided by one embodiment of the present invention.

Detailed Description

The present invention is described in further detail below with reference to specific embodiments and the attached drawings. It is intended that the present invention not be limited to the particular embodiments disclosed, but that the present invention be limited only by the appended claims.

Referring to fig. 1, the present invention provides a transmission protection method, including:

step S001, acquiring the acceleration of a rear wheel and the acceleration of a front wheel;

s002, selecting a quadrant of a coordinate axis where the vehicle working condition is located according to a comparison result of the acceleration of the rear wheel and zero, wherein the abscissa of the coordinate axis is a rear wheel acceleration calibration value, the ordinate is a front wheel acceleration calibration value, and acceleration calibration curves corresponding to different vehicle working conditions are arranged in the quadrant of the coordinate axis;

step S003, respectively finding front wheel acceleration calibration values corresponding to rear wheel acceleration calibration values equal to the rear wheel acceleration on the plurality of acceleration calibration curves;

step S004, the acceleration of the front wheel is respectively differenced with the acceleration calibration values of the front wheel corresponding to different acceleration calibration curves to obtain a plurality of difference values;

step S005, obtaining the working condition type of the vehicle according to the comparison result of the plurality of difference values and zero;

and step S006, adjusting a protection strategy of the gearbox according to the working condition type.

Fig. 4 is a schematic diagram of a vehicle from a low-friction road surface to a high-friction road surface, namely a low-adhesion to high-adhesion scene, and fig. 5 is a schematic diagram of a scene that the vehicle suddenly brakes high on the low-friction road surface (low-adhesion road surface).

In the prior art, aiming at the condition that the wheel speed is reduced by too large amplitude, a mode of directly disengaging gear and prompting the gearbox to break down is selected for solving, the mode easily causes power interruption in the running process of a vehicle, after the power of an engine is interrupted, the vehicle is easy to go out of a pit, refueling is needed after the vehicle is restarted, the running safety of the vehicle is affected, and the driving performance of the vehicle and the safety of the gearbox are difficult to balance by the single protection action. It is therefore necessary to identify such conditions and implement a protection strategy for the transmission when the vehicle encounters such conditions.

In the present embodiment, in step S001, the rear wheel acceleration and the front wheel acceleration are acquired, and the rear wheel acceleration and the front wheel acceleration are acquired from the control system of the vehicle.

In step S002, a quadrant of the coordinate axis where the vehicle operating condition is located is selected according to the comparison result between the rear wheel acceleration and zero, and in fig. 6, in the coordinate system, acceleration calibration curves are provided in the first quadrant and the third quadrant, which correspond to different operating condition types.

In step S003, the front wheel acceleration calibration values corresponding to the rear wheel acceleration calibration values equal to the rear wheel acceleration are found on the plurality of acceleration calibration curves, respectively.

And finding a rear wheel acceleration calibration value equal to the rear wheel acceleration on the abscissa of the coordinate axis, drawing a vertical line passing through the point, wherein a value of a vertical coordinate corresponding to the intersection point of the vertical line and the acceleration calibration curve is the front wheel acceleration calibration value.

In step S004, the acceleration of the front wheel is respectively differenced with the acceleration calibration values of the front wheel corresponding to the different acceleration calibration curves to obtain a plurality of difference values;

in step S005, the specific operating mode type is obtained according to the comparison result between the plurality of differences and zero.

And step S006, adjusting a protection strategy of the gearbox according to the working condition type. For example, when the operating mode is that the vehicle is in a driving state and the slip degree of the front wheels is low, the oil pressure of the driving pulley and the driven pulley of the gearbox needs to be increased.

Referring to fig. 2 and 3, the input end of the transmission controller inputs the speed of the left front wheel, the speed of the right front wheel, the speed of the left rear wheel, the speed of the right rear wheel, an accelerator pedal signal, a brake pedal signal and other brake signals, and the output end of the transmission controller is connected with the transmission. The whole algorithm is implemented in the gearbox controller.

The calculation method of the rear wheel acceleration comprises the following steps: a is_r＝(v′_n-v′_n-k）/(K×Δt)，a_rFor rear wheel acceleration, K is a periodic reference quantity, e.g. taking the value 20, v'_nIs a rear wheel speed value v 'at the nth time period'_n-kFor the rear wheel speed values at the n-k time period, Δ t is the time value for each period, e.g., 0.01 s. The rear wheel acceleration is calculated in real time or once per cycle at.

The method for calculating the acceleration of the front wheel comprises the following steps: a is_f＝(v_n-v_n-k)/(K×Δt)，a_fFor front wheel acceleration, K is a period scaling quantity, e.g. taking the values 20, v_nIs the value of the front wheel speed at the nth time period, v_n-kThe value of the front wheel speed at the n-k time period, Δ t, is the time value for each period, e.g., 0.01 s. The front wheel acceleration is calculated in real time or once per cycle at.

A reference value is obtained through calculation according to the strength of the steel belt, the vehicle weight and other parameter values, then the reference value is calibrated and adjusted to obtain an acceleration calibration curve, and the relation between the protection of the steel belt and the drivability is balanced in the calibration process of the acceleration calibration curve, so that the protection action on the gearbox needs to be timely involved to ensure that the steel belt is not damaged, and good driving experience of a vehicle needs to be ensured.

The embodiment solves the technical problems that in the prior art, when the wheel speed is too large in reduction range, the power interruption in the running process of the vehicle caused by direct gear disengagement and the failure prompt of the gearbox is solved, the running safety of the vehicle is influenced, and the driving performance of the vehicle and the safety of the gearbox are difficult to balance by the single protection action. By adopting the gearbox protection method provided by the embodiment, the front-mounted front-drive system of the vehicle can be protected, so that when the front wheels of the vehicle suddenly drive from a low-friction road surface to a high-friction road surface and the vehicle is emergently braked when running at high speed, the damage to the gearbox is reduced, a steel belt for transmitting power in the gearbox is protected, the steel belt is not broken, and the service life of the gearbox is prolonged.

Referring to FIG. 6, in one embodiment thereof, an acceleration calibration curve includes: the calibration curve calibration method comprises the following steps that a first calibration curve and a second calibration curve which are positioned in a first quadrant, and a third calibration curve and a fourth calibration curve which are positioned in a third quadrant are obtained;

the first calibration curve and the second calibration curve correspond to a low-attachment high-attachment working condition;

the third calibration curve and the fourth calibration curve correspond to the emergency braking working condition.

In the coordinate system of fig. 6, the first calibration curve and the second calibration curve in the first quadrant correspond to the low-adhesion to high-adhesion operating condition, and the low-adhesion to high-adhesion operating condition is the condition from the low-friction road surface to the high-friction road surface of the vehicle in fig. 4. Optionally, an area between the first calibration curve a and the second calibration curve B is a working condition area (first), an area between the first calibration curve a and the longitudinal axis is a working condition area (second), an area between the third calibration curve C and the fourth calibration curve D is a working condition area (third), an area between the fourth calibration curve D and the longitudinal axis is a working condition area (fourth), the working condition area (first) corresponds to a working condition with low adhesion and high adhesion with the working condition area (second), and the working condition area (third) corresponds to a working condition with low adhesion and sudden high braking on a road surface.

In this embodiment, two working conditions are respectively corresponding to different quadrants of a coordinate system, the first distinguishing is performed, and a mode of further refining the working conditions is provided by setting two calibration curves in each quadrant, so that the corresponding working conditions can be accurately identified, and a corresponding gearbox adjustment strategy is further refined, instead of singly and simply selecting a mode of directly disengaging and prompting that the gearbox breaks down as in the prior art, the solution of the prior art causes locking of an output wheel, power is continuously input from an engine input shaft, and the gearbox easily breaks a steel belt of transmission force.

In one embodiment, if the rear wheel acceleration is greater than zero, and the difference between the front wheel acceleration and the front wheel acceleration calibrated value corresponding to the first calibration curve is less than zero, and the difference between the front wheel acceleration and the front wheel acceleration calibrated value corresponding to the second calibration curve is greater than zero, it is determined that the type of the operating condition of the vehicle is a first operating condition, and the first operating condition is: the vehicle is in a driving state and the degree of slip of the front wheels is low. And judging which quadrant the working condition is located in according to the comparison of the acceleration of the rear wheel and zero, and if the difference between the acceleration of the front wheel and the acceleration calibrated value of the front wheel corresponding to the first calibrated curve is smaller than zero and the difference between the acceleration of the front wheel and the acceleration calibrated value of the front wheel corresponding to the second calibrated curve is larger than zero, judging that the type of the working condition of the vehicle is the first working condition, namely the vehicle is in a driving state and the slip degree grade of the front wheel is low. The first working condition is accurately judged by simultaneously meeting the three judgment conditions.

In one embodiment, adjusting the protection strategy of the gearbox according to the working condition type comprises: and if the working condition type of the vehicle is the first working condition, the oil pressure of the driving pulley and the driven pulley of the gearbox is increased. In the face of the condition that the vehicle is in a driving state and the slipping degree of the front wheels is low, the oil pressure of a driving pulley and a driven pulley of the gearbox is lifted to protect the gearbox, and a steel belt in the gearbox is protected.

In one embodiment, if the acceleration of the rear wheel is greater than zero and the difference between the acceleration of the front wheel and the calibrated value of the acceleration of the front wheel corresponding to the first calibration curve is greater than or equal to zero, it is determined that the type of the operating condition of the vehicle is a second operating condition, where the second operating condition is: the vehicle is in a driving state and the level of slip of the front wheels is high. By meeting the two conditions that the acceleration of the rear wheel is greater than zero and the difference between the acceleration of the front wheel and the calibrated value of the acceleration of the front wheel corresponding to the first calibrated curve is greater than or equal to zero, the working condition at the moment is accurately judged to be the second working condition, the vehicle is in a driving state, and the level of the slip degree of the front wheel is high.

In one embodiment, adjusting the protection strategy of the gearbox according to the working condition type comprises: and if the type of the working condition of the vehicle is the second working condition, the oil pressure of the driving belt wheel and the driven belt wheel of the gearbox is increased, and the hydraulic torque converter is opened at the same time. In the face of the second working condition: the vehicle is in a driving state and the level of the slip degree of the front wheels is high, at the moment, the oil pressure of a driving belt wheel and a driven belt wheel of the gearbox needs to be improved, and meanwhile, the hydraulic torque converter is opened, so that the gearbox is protected, and a steel belt in the gearbox is protected.

In one embodiment, if the rear wheel acceleration is less than zero, the difference between the absolute value of the front wheel acceleration and the absolute value of the front wheel acceleration calibrated value corresponding to the third calibration curve is greater than or equal to zero, and the difference between the absolute value of the front wheel acceleration and the absolute value of the front wheel acceleration calibrated value corresponding to the fourth calibration curve is less than zero, it is determined that the type of the operating condition of the vehicle is a third operating condition, where the third operating condition is: the vehicle is in a braking state and the degree of braking of the front wheels is low. If the acceleration of the rear wheel is less than zero, the difference between the absolute value of the acceleration of the front wheel and the absolute value of the acceleration calibration value of the front wheel corresponding to the third calibration curve is greater than or equal to zero, and the difference between the absolute value of the acceleration of the front wheel and the absolute value of the acceleration calibration value of the front wheel corresponding to the fourth calibration curve is less than zero, judging that the type of the working condition of the vehicle is a third working condition, and accurately judging whether the vehicle is in the third working condition by judging whether three conditions are simultaneously met: the vehicle is in a braking state and the degree of braking of the front wheels is low.

In one embodiment, adjusting the protection strategy of the gearbox according to the working condition type comprises: and if the type of the working condition of the vehicle is the third working condition, the hydraulic torque converter is opened. When the vehicle is in the third operating mode, the hydraulic torque converter is opened, and the gearbox and the steel belt in the gearbox are protected from being broken in this way.

In one embodiment, if the acceleration of the rear wheel is less than zero, and the difference between the absolute value of the acceleration of the front wheel and the absolute value of the calibrated value of the acceleration of the front wheel corresponding to the fourth calibration curve is greater than or equal to zero, it is determined that the working condition type of the vehicle is a fourth working condition, where the fourth working condition is: the vehicle is in a braking state and the level of braking of the front wheels is high. The vehicle is accurately judged to be in a fourth working condition by judging whether the conditions that the acceleration of the rear wheel is smaller than zero and the difference between the absolute value of the acceleration of the front wheel and the absolute value of the calibration value of the acceleration of the front wheel corresponding to the fourth calibration curve is larger than or equal to zero are met simultaneously: the vehicle is in a braking state and the level of braking of the front wheels is high.

In one embodiment, adjusting the protection strategy of the gearbox according to the working condition type comprises: and if the type of the working condition of the vehicle is the fourth working condition, opening the hydraulic torque converter and opening the forward gear clutch. When the vehicle is in the fourth working condition, the hydraulic torque converter is opened, and the forward gear clutch is opened, so that the gearbox and a steel belt in the gearbox are protected from being broken.

Referring to fig. 7, the present embodiment provides a transmission protection method, including:

firstly, calculating the acceleration of a rear wheel and the acceleration of a front wheel;

the calculation method of the rear wheel acceleration comprises the following steps: a is_r＝(v′_n-v′_n-k)/(K×Δt)，a_rFor rear wheel acceleration, K is a periodic reference quantity, e.g. taking the value 20, v'_nIs a rear wheel speed value v 'at the nth time period'_n-kFor the rear wheel speed values at the n-k time period, Δ t is the time value for each period, e.g., 0.01 s. The rear wheel acceleration is calculated in real time or once per cycle at.

The method for calculating the acceleration of the front wheel comprises the following steps: a is_f＝(v_n-v_n-k)/(K×Δt)，a_fFor front wheel acceleration, K is a period scaling quantity, e.g. taking the values 20, v_nIs the value of the front wheel speed at the nth time period, v_n-kThe value of the front wheel speed at the n-k time period, Δ t, is the time value for each period, e.g., 0.01 s. The front wheel acceleration is calculated in real time or once per cycle at.

Then, the next step is carried out according to whether the acceleration of the rear wheels is larger than zero, if so, the working condition of the vehicle is judged to be in the first quadrant, and a is calculated_rA corresponding to curve A_f1', calculating a_rA corresponding to curve B_f2If the working condition is less than or equal to zero, judging that the working condition of the vehicle is positioned in a third quadrant, and calculating a_rA corresponding to C curve_f3', calculating a_rA corresponding to D curve_f4′。

Secondly, when the working condition of the vehicle is positioned at a first quadrant, a is respectively calculated_f-a_f1’，a_f-a_f2' when the vehicle operating condition is in the third quadrant, a is respectively calculated_f-a_f3’，a_f-a_f4’。

When a is_f-a_f1’＜0&a_f-a_f2’≥0&a_rWhen the working condition of the vehicle is more than 0, judging that the working condition of the vehicle is a first working condition region between a first calibration curve A and a second calibration curve B; the protection action is to lift the oil pressure of the driving pulley and the driven pulley of the gearbox.

When a is_f-a_f1’≥0&a_rWhen the working condition of the vehicle is more than 0, judging that the working condition of the vehicle is a working condition area between the first calibration curve A and the longitudinal axis; and the protection action II is to lift the oil pressure of the driving belt wheel and the driven belt wheel of the gearbox and open the hydraulic torque converter at the same time.

When | a_f|-|a_f4’|＜0&|a_f|-|a_f3’|≥0&a_rWhen the vehicle working condition is less than 0, judging that the vehicle working condition is a working condition area (C) between the third calibration curve C and the fourth calibration curve D; the protection action is opening the hydraulic torque converter.

When | a_f|-|a_f4’|≥0&a_rWhen the vehicle working condition is less than 0, judging that the vehicle working condition is a working condition area between the fourth calibration curve D and the longitudinal axis; the protection action (iv) is to open the torque converter and open the forward clutch.

The gearbox protection method provided by the embodiment can accurately judge the working condition of the vehicle, so that different gearbox protection strategies are provided according to specific working conditions, and the service life of the gearbox is prolonged.

The invention provides a vehicle, which comprises the transmission protection method according to any one of the embodiments. The gearbox protection method provided by the invention can accurately judge the working condition of the vehicle, so that different gearbox protection strategies are provided according to specific working conditions, and the service life of the gearbox is prolonged.

The foregoing is considered as illustrative only of the principles and preferred embodiments of the invention. It should be noted that, for those skilled in the art, several other modifications can be made on the basis of the principle of the present invention, and the protection scope of the present invention should be regarded.