CN118082840A

CN118082840A - Transfer case control method and system and vehicle

Info

Publication number: CN118082840A
Application number: CN202410379805.5A
Authority: CN
Inventors: 王泽兴; 李红超
Original assignee: Great Wall Motor Co Ltd
Current assignee: Great Wall Motor Co Ltd
Priority date: 2024-03-29
Filing date: 2024-03-29
Publication date: 2024-05-28

Abstract

The application provides a transfer case control method, a transfer case control system and a vehicle, and belongs to the technical field of vehicles, wherein the transfer case control method comprises the following steps: responding to a switching instruction of a driving mode, acquiring a current driving mode and a first driving speed of a vehicle, wherein the driving mode comprises a high-speed four-wheel-drive mode, a low-speed four-wheel-drive mode and a timely four-wheel-drive mode; switching the current running mode based on the switching instruction and the first vehicle speed; acquiring the states of friction plates of the transfer case in real time, wherein the states of the friction plates comprise a sliding state and a static state; determining an anti-skid control strategy based on the switched running mode and the friction plate state; executing the anti-slip control strategy. The technical scheme of the application can reduce the loading and disconnecting frequency of the transfer case, thereby realizing the technical effect of avoiding the friction plate sliding grinding of the transfer case while meeting the torque transmission requirement between the main driving shaft and the auxiliary driving shaft of the vehicle.

Description

Transfer case control method and system and vehicle

Technical Field

The application relates to the technical field of vehicles, in particular to a transfer case control method and system and a vehicle.

Background

The four-wheel drive vehicle is a vehicle in which four wheels are all driving wheels. The four-wheel drive vehicle includes different four-wheel drive modes, such as a high-speed four-wheel drive mode applied under a high-speed running condition and a low-speed four-wheel drive mode applied under a low-speed running condition. On a four-drive vehicle equipped with a transfer case, conversion between the four-drive mode and the two-drive mode can be achieved by controlling engagement and disengagement of transfer case friction plates.

In the related art, the engagement torque of the transfer case is calculated based on the engine output torque, the gear signal, and the like. However, when the vehicle runs under the complex road conditions such as sand, the engagement torque is calculated through the technical scheme in the related technology, so that the transfer case is frequently loaded or disconnected, and further the friction plate of the transfer case is subjected to sliding abrasion in the loading and disconnecting processes.

Disclosure of Invention

Based on the method, the system and the vehicle for controlling the transfer case, the application provides a transfer case control method, a transfer case control system and a vehicle, so that the problem of how to avoid sliding and grinding of friction plates of the transfer case is solved.

In a first aspect of an embodiment of the present application, there is provided a transfer case control method, including:

Responding to a switching instruction of a driving mode, acquiring a current driving mode and a first driving speed of a vehicle, wherein the driving mode comprises a high-speed four-wheel-drive mode, a low-speed four-wheel-drive mode and a timely four-wheel-drive mode;

switching the current running mode based on the switching instruction and the first vehicle speed;

Acquiring the states of friction plates of the transfer case in real time, wherein the states of the friction plates comprise a sliding state and a static state;

determining an anti-skid control strategy based on the switched running mode and the friction plate state;

Executing the anti-slip control strategy;

The anti-slip control strategy comprises controlling the transfer case to be in preset engagement torque and controlling the actual engagement torque of the transfer case to be reduced along with the increase of a second vehicle speed of the vehicle in the switched running mode.

Optionally, the preset engagement torque is a maximum engagement torque of the transfer case, and the determining an anti-slip control strategy based on the switched running mode and the friction plate state includes:

determining the slip control strategy to control the transfer case at the maximum engagement torque with the friction plate state being the slip state;

and determining the anti-slip control strategy based on the switched running mode when the friction plate state is the stationary state.

Optionally, the determining the anti-slip control strategy based on the switched driving mode includes:

If the switched running mode is the high-speed four-wheel drive mode, determining that the anti-skid control strategy is to control the actual engagement torque of the transfer case, wherein the actual engagement torque is reduced along with the increase of the second vehicle speed of the vehicle in the switched running mode;

and if the switched running mode is the low-speed four-wheel drive mode, determining the anti-skid control strategy to control the transfer case to be in the maximum engagement torque.

Optionally, the controlling the actual engagement torque of the transfer case to decrease with an increase in the second vehicle speed of the vehicle in the switched travel mode includes:

determining a target speed section in which the second vehicle speed is located from a plurality of speed sections; wherein each speed segment corresponds to a torque adjustment coefficient, and a higher speed segment corresponds to a smaller torque adjustment coefficient, the torque adjustment coefficient being used to adjust the actual engagement torque;

And controlling the actual engagement torque of the vehicle based on the torque adjustment coefficient corresponding to the target speed segment and the maximum engagement torque of the transfer case.

Optionally, before determining the target speed segment in which the second vehicle speed is located from the plurality of speed segments, the method further includes:

Acquiring running parameters of the vehicle, wherein the running parameters comprise the load of the whole vehicle and/or the output torque of a power assembly;

Determining a torque adjustment coefficient corresponding to the speed segment based on the driving parameter; and the corresponding torque adjustment coefficients of the same speed section are different under different running parameters.

Optionally, the driving parameters include a load of the whole vehicle, and the torque adjustment parameters corresponding to the same speed section increase along with the increase of the load of the whole vehicle;

the running parameters include the output torque, and the torque adjustment parameters corresponding to the same speed segment are increased as the output torque increases.

Optionally, the current running mode is the high-speed four-wheel drive mode, and the switching the current running mode based on the switching instruction and the first vehicle speed includes:

Under the condition that the switching instruction indicates that the current running mode is switched to the timely four-wheel-drive mode, based on the first vehicle speed, a monitoring parameter and a target threshold value corresponding to the monitoring parameter are obtained, wherein the monitoring parameter comprises an accelerator pedal opening degree and/or a steering angle;

Executing the switching instruction under the condition that the monitoring parameter is smaller than the target threshold value;

And outputting prompt information when the monitoring parameter is greater than or equal to the target threshold, wherein the prompt information is used for prompting a user that the vehicle is currently forbidden to be switched from the high-speed four-wheel-drive mode to the timely four-wheel-drive mode.

Optionally, the acquiring the monitoring parameter and the target threshold corresponding to the monitoring parameter based on the first vehicle speed includes:

Acquiring the accelerator pedal opening and a first target threshold corresponding to the accelerator pedal opening under the condition that the first vehicle speed is smaller than a preset speed; wherein the first target threshold value increases with an increase in the first vehicle speed;

acquiring the accelerator pedal opening, the steering angle, the first target threshold value and a second target threshold value corresponding to the steering angle under the condition that the first vehicle speed is greater than or equal to the preset speed; wherein the second target threshold decreases as the first vehicle speed increases.

In a second aspect of the embodiment of the present application, there is provided a transfer case control system, an acquisition module, configured to acquire a current running mode of a vehicle, and a maximum engagement torque of the transfer case;

The first acquisition module is used for responding to a switching instruction of a driving mode, acquiring a current driving mode and a first driving speed of the vehicle, wherein the driving mode comprises a high-speed four-wheel-drive mode, a low-speed four-wheel-drive mode and a timely four-wheel-drive mode;

the mode switching module is used for switching the current running mode based on the switching instruction and the first vehicle speed;

The second acquisition module is used for acquiring the friction plate state of the transfer case in real time, wherein the friction plate state comprises a sliding state and a static state;

the strategy determining module is used for determining an anti-skid control strategy based on the switched running mode and the friction plate state;

the execution module is used for executing the anti-skid control strategy;

According to a third aspect of the embodiment of the present application, a vehicle is provided, which includes the transfer case control system according to the second aspect of the embodiment of the present application, or includes a control module, where the control module is configured to implement the steps of the transfer case control method according to the first aspect of the application embodiment.

The application provides a transfer case control method, a transfer case control system and a vehicle, wherein the transfer case control method comprises the following steps: responding to a switching instruction of a driving mode, acquiring a current driving mode and a first driving speed of a vehicle, wherein the driving mode comprises a high-speed four-wheel-drive mode, a low-speed four-wheel-drive mode and a timely four-wheel-drive mode; switching the current running mode based on the switching instruction and the first vehicle speed; acquiring the states of friction plates of the transfer case in real time, wherein the states of the friction plates comprise a sliding state and a static state; determining an anti-skid control strategy based on the switched running mode and the friction plate state; executing the anti-slip control strategy; the anti-slip control strategy comprises controlling the transfer case to be in preset engagement torque and controlling the actual engagement torque of the transfer case to be reduced along with the increase of a second vehicle speed of the vehicle in the switched running mode.

According to the application, different engagement torque is adopted to determine an anti-skid control strategy according to different running modes and differences between different friction plate states. The anti-skid control strategy specifically comprises the steps of controlling the transfer case to be in preset engagement torque and controlling the actual engagement torque of the transfer case to be reduced along with the increase of the second vehicle speed after the vehicle is switched. The technical scheme of the application can reduce the loading and disconnecting frequency of the transfer case, thereby realizing the technical effect of avoiding the friction plate sliding grinding of the transfer case while meeting the torque transmission requirement between the main driving shaft and the auxiliary driving shaft of the vehicle.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments of the present application will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a step diagram of a transfer case control method provided by an embodiment of the present application;

FIG. 2 is a diagram of steps in a method for determining a torque adjustment coefficient based on a speed segment according to an embodiment of the present application;

FIG. 3 is a diagram of steps in a method for determining a torque adjustment coefficient based on a driving parameter according to an embodiment of the present application;

FIG. 4 is a step diagram of a driving mode switching control method according to an embodiment of the present application;

FIG. 5 is a flow chart of a transfer case control method provided by an embodiment of the present application;

Fig. 6 is a schematic structural diagram of a transfer case control system according to an embodiment of the present application.

Detailed Description

The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

The four-wheel drive vehicle is a vehicle in which four wheels are all driving wheels. The four-wheel drive vehicle includes different four-wheel drive modes, such as a high-speed four-wheel drive mode applied under a high-speed running condition and a low-speed four-wheel drive mode applied under a low-speed running condition. A transfer case refers to a device connected between a main drive shaft and a secondary drive shaft for transmitting torque between the main drive shaft and the secondary drive shaft. On a four-drive vehicle equipped with a transfer case, conversion between the four-drive mode and the two-drive mode can be achieved by controlling engagement and disengagement of transfer case friction plates.

In the related art, no matter the vehicle is in a timely four-wheel drive mode, a high-speed four-wheel drive mode or a low-speed four-wheel drive mode, the transfer case controller calculates the torque required by the front axle of the vehicle in real time by identifying an engine output torque signal, a gear signal and the like, and further determines the engagement torque of the transfer case according to the torque required by the front axle of the vehicle when the friction plate of the transfer case is or is about to be slipped.

The joint torque determining method in the related art runs on a flat road condition without problems, but under off-road conditions with large fluctuation of road surfaces such as sand, the output torque of a power system such as an engine is large, the road conditions are complex, and the difference between front wheel speed and rear wheel speed is large, so that when the joint torque determining method in the related art is applied to the off-road conditions, the situation that the joint torque is frequently loaded and disconnected can occur, frequent sliding and grinding of friction plates can be caused, finally, the transfer case is overheated due to heat, and then the transfer case is returned to a two-drive mode, the off-road trafficability of a vehicle is affected, and the off-road performance of the vehicle is reduced. Meanwhile, the vehicle provided with the transfer case has no central mechanical lock, so that the high-strength off-road and crossing cannot be carried out on the off-road condition according to the joint torque control strategy in the related technology, and the four-wheel drive stability is poor.

The slipping mill refers to a state that the relative position between two mutually-engaged friction plates of the transfer case changes.

When the friction plates in the joint state are subjected to sliding friction, a large amount of friction heat is generated on the surfaces of the friction plates, so that the transfer case is overheated to disconnect the joint of the friction plates, and the vehicle is automatically switched from the four-wheel drive mode to the two-wheel drive mode. Therefore, the sliding friction plate of the transfer case affects the stability of the four-wheel drive mode, and has serious negative effects on the running of the vehicle.

Based on the above, in order to solve the problem of how to avoid slipping and grinding of friction plates of a transfer case, the application provides a transfer case control method, a transfer case control system and a vehicle, wherein different engagement torque is adopted to determine an anti-slip control strategy according to different driving modes and differences between different friction plate states. The anti-skid control strategy specifically comprises the steps of controlling the transfer case to be in preset engagement torque and controlling the actual engagement torque of the transfer case to be reduced along with the increase of the second vehicle speed after the vehicle is switched. The technical scheme of the application can reduce the loading and disconnecting frequency of the transfer case, thereby realizing the technical effect of avoiding the friction plate sliding grinding of the transfer case while meeting the torque transmission requirement between the main driving shaft and the auxiliary driving shaft of the vehicle. The specific method comprises the following steps:

the first aspect of the present application proposes an embodiment, as shown in a step diagram of a transfer case control method shown in fig. 1, where the method is applied to a vehicle, and specifically applied to a transfer case controller of the vehicle, and the main steps include:

Step S101, in response to a switching instruction of the running mode, acquiring a current running mode of the vehicle and a first vehicle speed.

The driving mode comprises a high-speed four-wheel-drive mode, a low-speed four-wheel-drive mode and a timely four-wheel-drive mode.

Step S102, switching the current running mode based on the switching command and the first vehicle speed.

Step S103, the states of friction plates of the transfer case are obtained in real time.

The friction plate states include a skid state and a rest state.

Step S104, determining an anti-slip control strategy based on the switched running mode and the friction plate state.

Step S105, executing the anti-slip control strategy.

The driving modes of the vehicle comprise a high-speed four-wheel drive mode, a low-speed four-wheel drive mode and a timely four-wheel drive mode. The high-speed four-wheel drive mode is generally applied to a scene with relatively flat road conditions such as an expressway or an asphalt road surface, the low-speed four-wheel drive mode is generally applied to a scene with relatively complex road conditions such as a climbing, a cross-country, a crossing of a desert, a muddy road surface, and the like, and the timely four-wheel drive mode is a mode of converting into four-wheel drive only when the driving is proper, and still being two-wheel drive under other conditions.

The high-speed four-wheel-drive mode and the low-speed four-wheel-drive mode can be determined according to the transmission ratio of the vehicle, and when the transmission ratio is higher than a preset threshold value, the driving mode can be determined to be the high-speed four-wheel-drive mode; when the gear ratio is lower than the preset threshold, the running mode can be determined to be a low-speed four-wheel drive mode.

The switching instruction is a control instruction for instructing the vehicle to switch from one driving mode to another driving mode, and may be triggered by a user through an entity or a virtual key on the vehicle, or triggered by the vehicle controller based on other driving parameters of the vehicle.

The friction plate states of the transfer case include a stationary state and a slip state. In the stationary state, the friction plates of the transfer case are relatively stationary, and in the slip state, there is a relative displacement between the friction plates of the transfer case.

The application scenes of different running modes of the vehicle are different, the emphasis of the conversion of the output power of the vehicle engine into the output rotating speed or the output torque is different, and the change rule of the torque transmitted by the main driving shaft to the auxiliary driving shaft is also different. Meanwhile, the different states of the friction plates of the transfer case also determine the different torque transmission efficiency of the main drive shaft and the auxiliary drive shaft. Therefore, it is necessary to determine the slip control strategy in combination with the running mode after the vehicle is switched and the friction plate state at the same time.

Optionally, the preset engagement torque is the maximum engagement torque of the transfer case, and the determining the anti-slip control strategy in step S104 based on the switched running mode and the friction plate state includes the following two cases:

In case one, the slip control strategy is determined to control the transfer case at the maximum engagement torque in the case where the friction plate state is the slip state.

And secondly, when the friction plate state is the static state, determining the anti-skid control strategy based on the switched running mode.

The maximum engagement torque of the transfer case is the maximum value of engagement torque which can be realized by the transfer case, the maximum engagement torque of the transfer case is determined by the mechanical structure of the transfer case, the maximum engagement torque of the transfer case can be determined based on parameters such as type or model, and the like, and the maximum engagement torque is preset in a storage unit connected with a transfer case controller, so that the transfer case obtains the maximum engagement torque from the storage unit.

When the friction plates are in a sliding friction state, the relative displacement exists between the friction plates of the transfer case, the efficiency of transmitting torque by the main driving shaft to the auxiliary driving shaft is reduced, and meanwhile friction heat generation starts between the friction plates of the transfer case. At this time, in order to improve the efficiency of torque transmission from the main drive shaft to the auxiliary drive shaft and to avoid overheating of the friction plates of the transfer case, the transfer case should be controlled at the maximum engagement torque.

When the friction plates are in a static state, the friction plates of the transfer case are relatively static, the efficiency of transmitting torque from the main driving shaft to the auxiliary driving shaft is high, and meanwhile, no friction heat is generated between the friction plates of the transfer case. At this time, in order to avoid the friction plate state from being shifted from the stationary state to the slip state, the slip control strategy should be determined further based on the running mode.

Optionally, in the second case, when the friction plate state is the stationary state, the anti-slip control strategy is determined based on the switched running mode, and the method further includes the following two sub-cases:

Sub-case one: and if the switched running mode is the high-speed four-wheel drive mode, determining that the anti-skid control strategy is to control the actual engagement torque of the transfer case, wherein the actual engagement torque is reduced along with the increase of the second speed of the vehicle in the switched running mode.

Sub-case two: and if the switched running mode is the low-speed four-wheel drive mode, determining the anti-skid control strategy to control the transfer case to be in the maximum engagement torque.

When the running mode is the high-speed four-wheel drive mode, the output power of the vehicle engine is converted more into the output rotational speed and less into the output torque, and the smaller the engine output torque is, the smaller the torque transmitted from the main drive shaft to the sub-drive shaft is. Meanwhile, the high-speed four-wheel drive mode is generally applied to scenes with relatively flat road conditions such as expressways or asphalt roads, and torque fluctuation transmitted by the main drive shaft to the auxiliary drive shaft is relatively small. Thus, the slip control strategy may be determined to control the actual engagement torque of the transfer case to decrease with increasing second vehicle speed.

Because the low-speed four-wheel drive mode is generally applied to scenes with complex road conditions such as climbing, cross-country, passing through desert, muddy road and the like, the torque fluctuation transmitted by the main driving shaft to the auxiliary driving shaft is larger. To avoid peak torque transfer from the primary drive shaft to the secondary drive shaft, the transfer case friction plates are caused to slip, so the transfer case should be controlled to be at maximum engagement torque.

According to the embodiment, different engagement torque determination strategies are adopted for the two modes according to the difference between application scenes of the high-speed four-wheel drive mode and the low-speed four-wheel drive mode. In the high-speed four-wheel drive mode, the engagement torque is determined based on the current second vehicle speed of the vehicle, the engagement torque is controlled to be increased or unchanged along with the increase of the second vehicle speed, and the engagement torque of the transfer case is controlled to be the maximum engagement torque in the low-speed four-wheel drive mode, so that the engagement torque of the transfer case can meet the torque transmission requirement between a main driving shaft and a secondary driving shaft of the vehicle, and the technical effect of avoiding friction plate slipping of the transfer case is realized.

Optionally, referring to a method step diagram for determining a torque adjustment coefficient based on a speed segment shown in fig. 2, the actual engagement torque of the transfer case is controlled to decrease with an increase in the second vehicle speed of the vehicle in the switched running mode, specifically comprising the steps of:

And S11, determining a target speed section in which the second vehicle speed is located from a plurality of speed sections.

Wherein each speed segment corresponds to a torque adjustment coefficient, and a higher speed segment corresponds to a smaller torque adjustment coefficient for adjusting the actual engagement torque.

And step S12, controlling the actual engagement torque of the vehicle based on the torque adjustment coefficient corresponding to the target speed section and the maximum engagement torque of the transfer case.

The speed segment may be referred to as a speed range or a speed interval, and may be specifically represented by an inequality sign or an interval. For example, the speed section may be [0km/h,20km/h ].

The speed segment has a plurality of speed segments. For example, the plurality of velocity bands may be respectively (0 km/h,30km/h ], (30 km/h,50km/h ], (50 km/h,70km/h ], (70 km/h,100 km/h), (100 km/h, + -infinity) if the second vehicle speed is 45km/h, the target speed section at which the second vehicle speed is located may be determined to be (30 km/h,50 km/h).

Reference is made to a table of correspondence between speed segments and torque adjustment coefficients as shown in table one.

Table one:

vehicle speed section	Torque adjustment coefficient
		(0km/h,30km/h]	100％
(30km/h,50km/h]	85％
		(50km/h,70km/h]	60％
(70km/h,100km/h]	50％
		(100km/h,+∞)	40％

Since the torque adjustment coefficient corresponding to the speed section (30 km/h,50 km/h) shown in table one is 85%, it can be determined that the corresponding torque adjustment coefficient is 85% when the second vehicle speed is 45 km/h.

After determining the torque adjustment coefficient corresponding to the target speed segment, in an alternative embodiment, the actual engagement torque may be determined as the product between the torque adjustment coefficient corresponding to the target speed segment and the maximum engagement torque.

In the embodiment, the plurality of speed sections and the torque adjustment coefficient corresponding to each speed section are arranged, and the actual engagement torque is determined through the torque adjustment coefficient corresponding to the target speed section where the second vehicle speed is located, so that the information processing flow of the transfer case controller can be effectively simplified. Meanwhile, under the condition that the vehicle speed frequently fluctuates, the actual engagement torque is prevented from being stirred along with the vehicle speed, the stability of the engagement torque of the transfer case is ensured, and the sliding grinding of the friction plate of the transfer case is further prevented.

Optionally, referring to a method step chart for determining a torque adjustment coefficient based on a driving parameter shown in fig. 3, before the step S11 of determining a target speed segment in which the second vehicle speed is located from a plurality of speed segments, specific steps include:

step S13, acquiring the running parameters of the vehicle.

The driving parameters comprise the load of the whole vehicle and/or the output torque of the power assembly.

And step S14, determining a torque adjustment coefficient corresponding to the speed section based on the running parameter.

And the corresponding torque adjustment coefficients of the same speed section are different under different running parameters.

The driving parameters of the vehicle may include the load of the whole vehicle, or include the output torque of the powertrain, or include the load of the whole vehicle and the output torque. The powertrain may be an engine assembly in a conventional powered vehicle or a drive motor assembly in an electrically driven vehicle, or an engine assembly and a drive motor assembly in a hybrid vehicle.

The load of the whole vehicle is the load borne by the vehicle, and can be obtained by a weight sensor arranged on a suspension. The output torque of the powertrain can be obtained by a dynamic torque sensor.

The different running parameters determine that the vehicle keeps the same running speed, the output torque output by the power assembly is controlled to be different, and the torque transmitted by the main driving shaft to the auxiliary driving shaft is further determined according to the different output torques of the power assembly. Therefore, according to the driving parameters, the torque adjustment coefficients corresponding to the same speed section are required to be adjusted, so that the transfer case is suitable for different requirements of the vehicle on the actual engagement torque under the same speed section.

For example, in the case of a speed section of (30 km/h,50 km/h), the corresponding torque adjustment coefficient is 80% when the vehicle load is 1800kg, and the corresponding torque adjustment coefficient is 90% when the vehicle load is 2000 kg.

When determining the actual engagement torque, the embodiment also considers the influence of the load of the whole vehicle and the output torque of the power assembly on the engagement torque, thereby improving the fit degree of the actual engagement torque and the state of the vehicle and ensuring the accuracy of the actual engagement torque.

Optionally, the driving parameters include a load of the whole vehicle, and the torque adjustment parameters corresponding to the same speed segment increase with the increase of the load of the whole vehicle.

The output power of the powertrain is equal to the product between the output torque and the output rotational speed, which determines the speed of the vehicle. Therefore, when the load of the whole vehicle increases, the output power of the power train needs to be increased in order to maintain the same running speed, and the output torque increases with the increase of the load of the whole vehicle because the running speed of the vehicle is unchanged and the output rotation speed is unchanged.

Because the output torque is increased, the torque transmitted by the main driving shaft and the auxiliary driving shaft is increased, under the same speed section, the torque adjustment coefficient is required to be increased along with the increase of the load of the whole vehicle and the output torque, so that the adaptation of the actual engagement torque and the current state of the vehicle is ensured, and the accuracy of the actual engagement torque is ensured.

Optionally, referring to a step diagram of a driving mode switching control method shown in fig. 4, the current driving mode is the high-speed four-wheel driving mode, and the step S102 of switching the current driving mode based on the switching command and the first vehicle speed further includes the following steps:

Step S1021, when the switching instruction indicates to switch the current running mode to the timely four-wheel-drive mode, acquiring a monitoring parameter and a target threshold corresponding to the monitoring parameter based on the first vehicle speed.

The monitored parameters include accelerator pedal opening and/or steering angle.

Executing the step S1022 in case the monitoring parameter is smaller than the target threshold; in the case where the monitoring parameter is greater than or equal to the target threshold, the step S1023 is performed.

Step S1022, executing the switching instruction.

Step S1023, outputting prompt information.

The prompt information is used for prompting a user that the vehicle is forbidden to be switched from the high-speed four-wheel drive mode to the timely four-wheel drive mode currently.

The timely four-wheel drive mode is a mode that the transfer case controller calculates the engagement torque in real time according to the opening signal of the accelerator pedal, the gear signal, the steering wheel angle signal and other whole vehicle signals so as to ensure that the vehicle has good traction and control performance on a flat road surface.

Since there is a steep drop in engagement torque of the transfer case when switching from the high-speed four-drive mode to the timely four-drive mode with the same vehicle speed. At this time, if the vehicle continues to accelerate, the friction plates of the transfer case are slipped. Based on this, when a switching instruction to switch from the high-speed four-wheel drive mode to the timely four-wheel drive mode is received, a monitoring parameter to be monitored for executing the switching instruction should be determined based on the first vehicle speed of the vehicle.

In an alternative manner, the switching command may be triggered based on a triggering action of a user, or may be sent to the transfer case controller by the whole vehicle controller based on a current running condition of the vehicle.

The monitored parameters may include an accelerator pedal opening, or include a steering angle, or include an accelerator pedal opening and a steering angle. When the monitoring parameter is smaller than the target threshold, the transfer case with the reduced engagement torque still can meet the requirement of the main drive shaft for transmitting torque to the auxiliary drive shaft if the high-speed four-drive mode is switched to the timely four-drive mode, and at the moment, a switching instruction can be executed.

When the monitored parameter is greater than or equal to the target threshold, the transfer case with reduced engagement torque cannot meet the requirement of the primary drive shaft to the secondary drive shaft for transmitting torque if the high-speed four-drive mode is switched to the timely four-drive mode. At this time, if the torque switching is forcibly performed, the transfer case is subjected to friction plate slipping. A prompt message should be output to the user to prompt the user that the vehicle is currently prohibited from switching from the high-speed four-wheel drive mode to the timely four-wheel drive mode.

In an alternative embodiment, the prompt information may be voice information, text information, or image information. Taking voice information as an example, the prompt information may be "do not use timely four-drive mode currently".

In the embodiment, in response to the triggering of the switching instruction, the monitoring parameter to be monitored in the mode switching is determined through the first speed of the vehicle, and the switching instruction is executed under the condition that the monitoring parameter is smaller than the target threshold value, so that the friction plate slipping caused by the mode switching can be effectively avoided.

Optionally, in step S1021, based on the first vehicle speed of the vehicle, a monitoring parameter and a target threshold corresponding to the monitoring parameter are obtained based on the first vehicle speed, including the following two cases, namely, the following case one and the following case two, specifically:

in a first aspect, the accelerator opening and a first target threshold corresponding to the accelerator opening are obtained when the first vehicle speed is less than a preset speed. Wherein the first target threshold value increases with an increase in the first vehicle speed

And secondly, acquiring the accelerator pedal opening, the steering angle, the first target threshold value and a second target threshold value corresponding to the steering angle under the condition that the first vehicle speed is greater than or equal to the preset speed. Wherein the second target threshold decreases as the first vehicle speed increases.

When the first vehicle speed is smaller than the preset speed, the slipping of the friction plate is mainly determined by the opening degree of the accelerator pedal, so that only the opening degree of the accelerator pedal is acquired, and a first target threshold value of the opening degree of the accelerator pedal at the current first vehicle speed is acquired at the same time.

When the first vehicle speed is greater than or equal to the preset speed, the sliding abrasion of the friction plate is determined by the opening degree of the accelerator pedal and the steering angle at the same time, so that the opening degree of the accelerator pedal and the steering angle are acquired, and a first target threshold value at the current first vehicle speed and a second target threshold value of the steering angle are acquired at the same time.

In an alternative embodiment, the preset speed may be 40km/h, or set by the user himself.

Since the output power of the powertrain will be converted into an output rotational speed more as the running speed of the vehicle is greater, the torque transmitted from the main drive shaft to the sub-drive shaft through the transfer case increases less as the running speed is greater with the same accelerator pedal opening. It follows that the first target threshold value should be increased as the first vehicle speed increases.

Meanwhile, since the auxiliary drive shaft is usually a steering shaft, a certain rotation speed drop occurs to the auxiliary drive shaft due to partial running resistance when the vehicle turns, and the larger the steering angle is, the larger the rotation speed drop amplitude of the auxiliary drive shaft is, so that the possibility of slipping and grinding of the transfer case is increased. Therefore, the second target threshold should decrease with an increase in the first vehicle speed.

In an alternative embodiment, the steering angle may in particular be a steering wheel angle or a steering wheel deflection angle, which may be detected by a steering wheel angle sensor.

Further, when the vehicle speed is 0km/h, since there is no torque transmission between the main drive shaft and the sub-drive shaft, the acquisition of the accelerator pedal and the steering angle can be stopped.

According to the embodiment, when the first vehicle speed is smaller than the preset speed, only the opening degree of the accelerator pedal is monitored, and when the first vehicle speed is larger than or equal to the preset speed, the opening degree of the accelerator pedal and the steering angle are monitored simultaneously, so that the calculation resources of the transfer case controller are saved, the sliding abrasion of the transfer case is effectively avoided, and the control precision of the engagement torque of the transfer case is improved.

Based on the above-described embodiments, an exemplary description will be made below regarding a transfer case control method according to the present application:

First, the transfer case control of the vehicle may store different torque adjustment coefficients corresponding to each of the plurality of speed segments under different running parameters in advance. Taking the running parameter as the whole load as an example, the transfer case control of the vehicle may store at least the following table two, the following table three, and the following table four in advance.

Wherein, the second table is different torque adjustment coefficients corresponding to each speed section when the load of the whole vehicle is 1800 kg; the third table is that when the load of the whole vehicle is 2000kg, different torque adjustment coefficients corresponding to each speed section are obtained;

table four shows the correspondence between the first vehicle speed and the first target threshold and the second target threshold, respectively.

And (II) table:

Table three:

vehicle speed section	Torque adjustment coefficient
		(0km/h,30km/h]	100％
(30km/h,50km/h]	95％
		(50km/h,70km/h]	75％
(70km/h,100km/h]	65％
		(100km/h,+∞)	55％

Table 5 four:

Referring to fig. 5, a flow chart of a transfer case engagement torque determination method is shown. The transfer case control method is applied to a vehicle, and is particularly applied to a transfer case controller of the vehicle. The method specifically comprises the following steps:

at the beginning of the method, first, a current running speed of the vehicle and a first vehicle speed are acquired in response to a switching instruction of a running mode.

Taking a preset speed of 40km/h as an example when the current running mode is a high-speed four-wheel-drive mode and the switching instruction indicates that the current running mode is switched to the timely four-wheel-drive mode, if the first vehicle speed is 30km/h, acquiring an accelerator pedal opening, and determining that a first target threshold value of the accelerator pedal opening is 10% when the first vehicle speed is 30 km/h. Based on this, if the accelerator pedal opening is less than 10%, executing a switching instruction; if the opening of the accelerator pedal is more than or equal to 10%, a prompt message is output to prompt a user that the current vehicle is forbidden to switch from the high-speed four-wheel drive mode to the timely four-wheel drive mode.

If the first vehicle speed is 60km/h, the accelerator pedal opening and the steering angle are obtained, and the first target threshold value of the accelerator pedal opening is 20% when the first vehicle speed is 60km/h and the second target threshold value of the steering angle is 120 ° when the first vehicle speed is 60km/h are determined. Based on this, if the accelerator pedal opening is less than 20% and the steering angle is less than 120 °, the switching instruction is instructed; if the opening of the accelerator pedal is larger than or equal to 20 percent or the steering angle is larger than or equal to 120 degrees, a prompt message is output to prompt a user that the current vehicle is forbidden to switch from the high-speed four-wheel drive mode to the timely four-wheel drive mode.

If the current running mode is not the high-speed four-wheel-drive mode or the switching instruction indicates that the current running mode is switched to the non-timely four-wheel-drive mode, responding to the switching instruction, and switching the current running mode to the running mode indicated by the switching instruction.

Subsequently, the friction plate state of the transfer case is acquired.

The transfer case is controlled to be at a maximum engagement torque in the case where the friction plate state is a slip state.

When the friction plate state is in the stationary state, if the traveling mode after switching is the low-speed four-wheel drive mode, the transfer case is controlled to be at the maximum engagement torque.

If the switched running mode is the high-speed four-wheel drive mode, the whole load of the vehicle is firstly obtained through a weight sensor arranged on a suspension. If the load of the whole vehicle is 1800kg, the target speed range is determined to be (30 km/h,50 km/h) when the second vehicle speed is 50km/h, and the further torque adjustment coefficient is the torque adjustment coefficient corresponding to (30 km/h,50 km/h) in table two, that is, 85%. Further, if the maximum engagement torque is 18000n·m, the actual engagement torque is determined to be 15300n·m, and the transfer case is controlled to be 15300n·m.

Based on the same inventive concept, the application also provides a transfer case control system, as shown in the structural schematic diagram of the transfer case control system shown in fig. 6, the system comprises:

the execution module is used for executing the anti-skid control strategy;

Optionally, the strategy determination module is further configured to determine the anti-slip control strategy to control the transfer case to be at the maximum engagement torque if the friction plate state is the slip state; and determining the anti-slip control strategy based on the switched running mode when the friction plate state is the stationary state.

Optionally, the strategy determining module is further configured to determine that the anti-slip control strategy is to control the actual engagement torque of the transfer case and decrease with an increase in the second vehicle speed of the vehicle in the switched driving mode if the switched driving mode is the high-speed four-wheel drive mode; and if the switched running mode is the low-speed four-wheel drive mode, determining the anti-skid control strategy to control the transfer case to be in the maximum engagement torque.

Optionally, the policy determining module is further configured to determine, from a plurality of speed segments, a target speed segment in which the second vehicle speed is located; each speed section corresponds to one torque adjustment coefficient, and the higher speed section corresponds to the smaller torque adjustment coefficient; and controlling the actual engagement torque of the vehicle based on the torque adjustment coefficient corresponding to the target speed segment and the maximum engagement torque of the transfer case.

Optionally, the strategy determining module is further configured to obtain a running parameter of the vehicle, where the running parameter includes a load of the whole vehicle and/or an output torque of the powertrain; determining a torque adjustment coefficient corresponding to the speed segment based on the driving parameter; and the corresponding torque adjustment coefficients of the same speed section are different under different running parameters.

Optionally, the driving parameters include a load of the whole vehicle, and the torque adjustment parameters corresponding to the same speed section increase along with the increase of the load of the whole vehicle; the running parameters include the output torque, and the torque adjustment parameters corresponding to the same speed segment are increased as the output torque increases.

Optionally, the mode switching module is further configured to, when the switching instruction indicates to switch the current running mode to the timely four-wheel-drive mode, obtain a monitoring parameter and a target threshold corresponding to the monitoring parameter based on the first vehicle speed, where the monitoring parameter includes an accelerator pedal opening and/or a steering angle; executing the switching instruction under the condition that the monitoring parameter is smaller than the target threshold value; and outputting prompt information when the monitoring parameter is greater than or equal to the target threshold, wherein the prompt information is used for prompting a user that the vehicle is currently forbidden to be switched from the high-speed four-wheel-drive mode to the timely four-wheel-drive mode.

Optionally, the mode switching module is further configured to obtain the accelerator pedal opening and a first target threshold corresponding to the accelerator pedal opening when the first vehicle speed is less than a preset speed; wherein the first target threshold value increases with an increase in the first vehicle speed; acquiring the accelerator pedal opening, the steering angle, the first target threshold value and a second target threshold value corresponding to the steering angle under the condition that the first vehicle speed is greater than or equal to the preset speed; wherein the second target threshold decreases as the first vehicle speed increases.

The embodiment of the application also provides a computer readable storage medium, on which a computer program/instruction is stored, which when executed by a processor, implements a transfer case control method as disclosed in the embodiment of the application.

The embodiment of the application also provides a vehicle, which comprises the transfer case control system or the control module, wherein the control module is used for realizing the steps of the transfer case control method.

In this specification, each embodiment is described in a progressive manner, and each embodiment is mainly described by differences from other embodiments, and identical and similar parts between the embodiments are all enough to be referred to each other.

Embodiments of the present application are described with reference to flowchart illustrations and/or block diagrams of methods, systems, electronic devices, and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing terminal device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal device, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

While preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiment and all such alterations and modifications as fall within the scope of the embodiments of the application.

Finally, it is further noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or terminal device that comprises the element.

The above detailed description of the method, system and vehicle for controlling the transfer case provided by the application applies specific examples to illustrate the principle and implementation of the application, and the above examples are only used to help understand the method and core idea of the application; meanwhile, as those skilled in the art will vary in the specific embodiments and application scope according to the idea of the present application, the present disclosure should not be construed as limiting the present application in summary.

Claims

1. A transfer case control method, the method comprising:

Executing the anti-slip control strategy;

2. The transfer case control method according to claim 1, wherein the preset engagement torque is a maximum engagement torque of the transfer case, the determining an anti-slip control strategy based on the switched running mode and the friction plate state includes:

3. The transfer case control method according to claim 2, characterized in that the determining the slip prevention control strategy based on the switched travel mode includes:

4. The transfer case control method according to claim 1, characterized in that said controlling the actual engagement torque of the transfer case to decrease with an increase in the second vehicle speed of the vehicle in the switched running mode includes:

5. The transfer case control method of claim 4, wherein prior to said determining a target speed segment from among a plurality of speed segments in which said second vehicle speed is located, said method further comprises:

6. The transfer case control method according to claim 5, wherein the running parameter includes a vehicle load, and the torque adjustment parameter corresponding to the same speed segment increases as the vehicle load increases;

7. The transfer case control method according to claim 1, wherein the current running mode is the high-speed four-wheel drive mode, and the switching of the current running mode based on the switching instruction and the first vehicle speed includes:

acquiring a monitoring parameter and a target threshold value corresponding to the monitoring parameter based on the first vehicle speed under the condition that the switching instruction indicates to switch from the current running mode to the timely four-wheel-drive mode, wherein the monitoring parameter comprises an accelerator pedal opening degree and/or a steering angle;

8. The transfer case control method according to claim 7, wherein the acquiring the monitoring parameter and the target threshold value corresponding to the monitoring parameter based on the first vehicle speed includes:

9. A transfer case control system, the system comprising:

the execution module is used for executing the anti-skid control strategy;

10. A vehicle comprising the transfer case control system of claim 9 or comprising a control module for implementing the steps of the transfer case control method of any one of claims 1-8.