Patent Description:
The present invention relates to the field of vehicle technology, and in particular to a method and system for intelligent four-wheel drive control, and a vehicle.

With a four-wheel drive system of a vehicle, engine power of the vehicle may be delivered, based on road conditions and vehicle conditions, to any wheel in demand, in order to maximize four-wheel adhesive force, and improve passability, maneuverability and acceleration performance of the vehicle. An intelligent four-wheel drive system can automatically adjust a four-wheel drive mode, so as to realize a four-wheel drive performance while ensuring good driving experience.

In a conventional intelligent four-wheel drive control system, it is usually necessary to monitor a temperature of a friction plate clutch to prevent the friction plate from being ablated and sintered, or prevent an early failure of the four-wheel drive system. In a conventional method for temperature monitoring, the temperature of oil where the friction plate is disposed is measured and monitored by using a temperature sensor, and the temperature of the friction plate is inferred. <CIT> discloses a clutch unit comprising a wet friction clutch for controllable transmission of a torque from an input element to an output element, oil for cooling the friction clutch, and an actuator for actuating the friction clutch.

However, in the conventional method for temperature monitoring, since the temperature of the monitored friction plate is inferred from the temperature of the oil, there are problems of monitoring lag and poor reliability. Due to the poor reliability of the friction plate temperature, there is no method of correcting an output torque based on the friction plate temperature.

In view of the above, an objective of the present invention is to provide a method and a system for intelligent four-wheel drive control, and a vehicle, in order to solve the problems of lag in monitoring a friction plate temperature, poor reliability of the friction plate temperature, and inability to correcting an output torque.

To achieve the objective, technical solutions of the present invention are provided according to the independent claims. Further embodiments are specified in the dependent claims.

According to the invention, a method for intelligent four-wheel drive control is provided, including:.

Further according to the invention, the step of calculating a temperature of the friction plate of the vehicle based on the front wheel speed, the rear wheel speed and the calculated output torque includes:.

Further according to the invention, the step of calculating the temperature of the friction plate of the vehicle based on the front-rear shaft speed difference and the calculated output torque includes:.

calculating a friction plate heat generation of the vehicle based on the front-rear shaft speed difference and the calculated output torque;.

In a further embodiment, the vehicle condition information further includes vehicle speed and ambient temperature, and after the step of calculating the temperature of the friction plate based on the friction plate heat generation and the friction plate heat dissipation, the method further includes:.

In a further embodiment, the step of correcting the calculated output torque based on the temperature of the friction plate, to obtain an actual output torque includes:.

Advantages of the method for intelligent four-wheel drive control in the present invention in comparison with the conventional technology are described as follows.

In the method for intelligent four-wheel drive control according to the present invention, a calculated output torque is calculated for a vehicle based on acquired vehicle condition information of the vehicle; then a temperature of the friction plate of the vehicle is calculated based on a front wheel speed, a rear wheel speed and the calculated output torque; and an actual output torque is obtained by correcting the calculated output torque based on the temperature of the friction plate, and a friction clutch of the vehicle is controlled to output the actual output torque. In the method for intelligent four-wheel drive control according to the present invention, the temperature of the friction plate is directly obtained based on real-time vehicle condition information, and thereby has higher accuracy; in addition, the calculated output torque is corrected by using the temperature of the friction plate, which improves control accuracy for the output torque, thereby improving maneuverability of the vehicle and an ability of the vehicle to get out of trouble, and reducing probability of ablation damage to the friction plate.

Another objective of the present invention is to provide a system for intelligent four-wheel drive control, in order to solve the problems of lag in monitoring a friction plate temperature, poor reliability of the friction plate temperature, and inability to correcting an output torque.

To achieve the objective, technical solutions of the present invention are provided as follows.

According to the invention, a system for intelligent four-wheel drive control is provided, including an acquisition module, a torque calculation module, a temperature calculation module and a torque control module.

The acquisition module is connected to the torque calculation module and the temperature calculation module, and the torque calculation module is connected to the temperature calculation module and the torque control module.

The acquisition module is configured to acquire vehicle condition information of a vehicle, where the vehicle condition information includes a front wheel speed and a rear wheel speed.

The torque calculation module is configured to calculate a calculated output torque based on the vehicle condition information.

The temperature calculation module is configured to calculate a temperature of a friction plate of the vehicle based on the front wheel speed, the rear wheel speed and the calculated output torque.

The torque calculation module is further configured to correct the calculated output torque based on the temperature of the friction plate to obtain an actual output torque.

The torque control module is configured to control a friction clutch to output the actual output torque.

Further according to the invention, the temperature calculation module is specifically configured to:.

In a further embodiment, the vehicle condition information further includes vehicle speed and ambient temperature, and the system further includes an overheat protection module.

The overheat protection module is connected to the temperature calculation module/.

The temperature calculation module is further configured to calculate, based on the friction plate heat dissipation, the vehicle speed and ambient temperature, a current oil temperature of the oil where the friction plate is disposed.

The overheat protection module is configured to transmit an overheat protection signal to the vehicle when the temperature of the friction plate meets a first preset condition and /or when the current oil temperature meets a second preset condition.

In a further embodiment, the torque calculation module is further configured to:
calculate a temperature correction coefficient based on the temperature of the friction plate; obtain a temperature-compensated output torque based on the calculated output torque and the temperature correction coefficient; calculate a drag torque based on the front-rear shaft speed difference; and obtain the actual output torque based on the drag torque and the temperature-compensated output torque.

Advantageous of the system for intelligent four-wheel drive control over the conventional technology are the same as those of the method for intelligent four-wheel drive control, which are not repeated herein.

Another objective of the present invention is to provide a vehicle, in order to solve the problems of lag in monitoring a friction plate temperature, poor reliability of the friction plate temperature, and inability to correcting an output torque.

To achieve the objective, a technical solution of the present invention is provided as follows.

According to the invention, a vehicle is provided, including the above-mentioned system for intelligent four-wheel drive control.

Advantageous of the vehicle over the conventional technology, are the same as those of the system for intelligent four-wheel drive control, which are not repeated herein. According to the invention, a computer program is provided, comprising computer readable codes, which, when being executed on a computing device, cause the computing device to perform the above-mentioned method for intelligent four-wheel drive control.

According to the invention, a computer-readable medium is provided, storing the above-mentioned computer program.

The technical solutions of the present application are briefly described above. For understanding the technical means of the present invention better and practicing the present invention, and for better understanding of the above and other objectives, features and advantages of the present invention, specific embodiments of the present invention are described below.

For a clearer illustration of the embodiments of the present invention or the technical solutions in the conventional technology, accompanying drawings required in the description of the embodiments or the conventional technology are introduced briefly below. Apparently, the drawings constituting a part of the present invention are intended to provide a further understanding of the present invention. Exemplary embodiments of the present invention and descriptions thereof are intended to explain the present invention, and do not constitute an undue limitation to the present invention. In the drawings:.

Reference numbers in the drawings are listed as follows.

It should be noted that, the embodiments of the present invention and features in the embodiments may be combined with each other as long as there is no conflict.

The present invention is described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

<FIG> is a flow chart of a method for intelligent four-wheel drive control according to an embodiment of the present invention.

The method for intelligent four-wheel drive control provided in the embodiment of the present invention is applicable to a vehicle. The method may include steps <NUM> to <NUM>.

In step <NUM>, vehicle condition information of a vehicle is acquired, where the vehicle condition information includes a front wheel speed and a rear wheel speed of the vehicle.

The method for intelligent four-wheel drive control provided in the embodiments of the present invention is mainly applied to an intelligent four-wheel drive system of a vehicle. The intelligent four-wheel drive system includes an electronic control unit and an electronically controlled torque manager. The electronically controlled torque manager includes a group of friction clutches. The electronically controlled torque manager may control a torque transmitted from a friction clutch in real time in response to an electronic control signal sent from the electronic control unit. The electronic control unit includes multiple modules for automatically controlling the four-wheel drive system based on different road conditions and vehicle condition information, so as to not only ensure passability, maneuverability, and acceleration performance of the vehicle, but also eliminate phenomena such as steering braking and vibration, realizing a balance between driving experience and four-wheel drive performance.

Specifically in an embodiment of the present invention, the vehicle condition information includes real-time condition information of the vehicle and basic information of the vehicle. The real-time condition information may include: vehicle speed, wheel speed, steering wheel angle signal, gear signal, engine torque, ambient temperature, shutdown time, and the like. The basic information may include: gear ratios of gearbox, rolling radius, wheelbase, ratio of turning angle, and the like.

In step <NUM>, a calculated output torque is calculated based on the vehicle condition information.

In an embodiment of the present invention, on the basis of step <NUM>, a calculated output torque of a friction clutch is calculated based on the acquired vehicle condition information, such as wheel speed, engine torque, gear signal and angle signal.

The embodiment of the present invention further includes step <NUM>.

In step <NUM>, a temperature of a friction plate of the vehicle is calculated based on the front wheel speed, the rear wheel speed and the calculated output torque.

In an embodiment of the present invention, the front wheel speed and the rear wheel speed mainly determine a front-rear shaft speed difference of the vehicle, and the front-rear shaft speed difference determines a pressing force and displacement of the friction plate in the friction clutch. A friction plate heat generation is mainly caused by friction. When the front-rear shaft speed difference is <NUM>, a temperature of the friction plate is mainly caused by the heat generation when the friction plate stirs oil. By combining the calculated output torque with the front wheel speed and the rear wheel speed, the calculation of the temperature of the friction plate may be more comprehensively and more accurate.

In step <NUM>, an actual output torque is obtained by correcting the calculated output torque based on the temperature of the friction plate.

In practical applications, a friction coefficient of the friction plate is affected by the temperature of the friction plate, where different temperatures correspond to different friction coefficients. The friction coefficient affects accuracy of the output torque. In the embodiment of the present invention, the calculated output torque is corrected based on the temperature of the friction plate. An actual output torque may be adjusted based on the temperature of the friction plate, so as to avoid excessive torque output when the temperature of the friction plate is high, thereby improving accuracy in controlling the actual output torque, reducing a probability of ablation of the friction plate, and improving the maneuverability of the vehicle and an ability of the vehicle to get out of trouble.

In step <NUM>, a friction clutch of the vehicle is controlled to output the actual output torque.

In the embodiment of the present invention, on the basis of step <NUM>, the torque control module in the electronic control unit obtains, based on the calculated actual output torque, a current required for the friction clutch; and controls, by using the current, the friction clutch to output the actual output torque. In this way, the probability of ablation damage to the friction plate is reduced while meeting actual needs of the vehicle.

In summary, the method for intelligent four-wheel drive control according to the embodiment of the present invention has at least the following advantages.

With the method for intelligent four-wheel drive control described in the embodiment of the present invention, a calculated output torque of a vehicle may be calculated based on acquired vehicle condition information of the vehicle; then a temperature of the friction plate of the vehicle may be calculated based on a front wheel speed, a rear wheel speed and the calculated output torque; and an actual output torque is obtained by correcting the calculated output torque based on the temperature of the friction plate, and a friction clutch of the vehicle is controlled to output the actual output torque. In the method for intelligent four-wheel drive control provided in the embodiments of the present invention, the temperature of the friction plate is directly obtained based on real-time vehicle condition information, and thereby has higher accuracy; in addition, the calculated output torque is corrected based on the temperature of the friction plate, which improves accuracy in controlling the output torque, thereby improving maneuverability of the vehicle and an ability of the vehicle to get out of trouble, and reducing probability of ablation damage to the friction plate.

<FIG> is a flow chart of a method for intelligent four-wheel drive control according to another embodiment of the present invention.

For a specific implementation of step <NUM>, reference may be made to step <NUM> in embodiment <NUM>.

In step <NUM>, a front-rear shaft speed difference is calculated based on the front wheel speed and the rear wheel speed.

The front-rear shaft speed difference indicates a difference between an average value of the front wheel speed and an average value of the rear wheel speed. The front-rear shaft speed difference is not only a main factor for friction plate heat generation, but also a main parameter in calculating a drag torque. The drag torque is a part of the actual output torque. In the embodiment of the present invention, the front-rear shaft speed difference and the drag torque are introduced in order to improve accuracy in calculating the temperature of the friction plate and improve accuracy of the actual output torque.

In step <NUM>, a friction plate heat generation of the vehicle is calculated based on the front-rear shaft speed difference and the calculated output torque.

In the embodiment of the present invention, the front-rear shaft speed difference and the calculated output torque are mainly used for calculating a work done by sliding friction on the friction plate. The work done by sliding friction is a main source of a temperature rise on the friction plate, and the friction plate heat generation may be calculated from the work done by sliding friction.

In step <NUM>, a historical temperature of oil where the friction plate is disposed is acquired.

In the embodiment of the present invention, after the friction plate heat generation is calculated in step <NUM>, a friction plate heat dissipation is further considered. In practical applications, heat on the friction plate is dissipated through the oil where the friction plate is disposed.

In step <NUM>, a friction plate heat dissipation is calculated based on the historical temperature.

In the embodiment of the present invention, a real-time oil temperature is obtained based on the friction plate heat dissipation, and the friction plate heat dissipation is calculated by using the historical temperature of the oil.

In step <NUM>, the temperature of the friction plate is calculated based on the friction plate heat generation and the friction plate heat dissipation.

In the embodiment of the present invention, a variation in the temperature of the friction plate may be calculated by subtracting the friction plate heat dissipation from the friction plate heat generation, and then integration may be performed on the variation to obtain the temperature of the friction plate.

In the method for calculating the temperature of the friction plate according to the embodiment of the present invention, an influence of the front-rear shaft speed difference on the temperature of the friction plate is considered, and accuracy in calculating the temperature of the friction plate is improved, which leads to lower cost, better real-time performance, and a lightweight characteristic, in comparison with an indirect calculation of the temperature of the friction plate through a temperature sensor.

In step <NUM>, a current oil temperature of the oil where the friction plate is disposed is calculated based on the friction plate heat dissipation, the vehicle speed and the ambient temperature.

In the embodiment of the present invention, a current oil temperature of the oil where the friction plate is disposed may be calculated accurately based on the friction plate heat dissipation in combination with a vehicle speed and ambient temperature. The friction plate heat dissipation is a main heat source for the oil. In addition, the vehicle speed and ambient temperature have a certain influence on heat dissipation of the oil. With the method for calculating the current oil temperature according to the embodiment of the present invention, calculation is simplified and cost is reduced while ensuring accuracy in calculating the current oil temperature.

In step <NUM>, an overheat protection signal is transmitted to the vehicle when the temperature of the friction plate meets a first preset condition and /or when the current oil temperature meets a second preset condition.

In the embodiment of the present invention, an overheat protection may be applied to the vehicle if the temperature of the friction plate is excessively high or the current oil temperature is excessively high, that is, when the temperature of the friction plate meets a first preset condition and /or when the current oil temperature meets a second preset condition. In this way, a driver may be reminded to decelerate the vehicle when the temperature of the friction plate is excessively high or the current oil temperature is excessively high, so as to reduce probability of ablation damage to the friction plate.

In an example, the first preset condition may be that the temperature of the friction plate is greater than <NUM>, and the second preset condition may be that the current oil temperature is greater than <NUM>. Either the temperature of the friction plate meeting the first preset condition or the current oil temperature meeting the second preset condition may trigger the overheat protection signal to the vehicle, reminding the driver that the four-wheel drive system is overheat and the vehicle should be decelerated. The transmission of the overheat protection signal is terminated when the temperature of the friction plate does not meet the first preset condition and the current oil temperature does not meet the second preset condition.

In a practical application, the overheat protection signal may be a piece of text information displayed on an instrument screen of the vehicle, or may be an overheat alert.

In the embodiment of the present invention, based on the temperature of the friction plate calculated in step <NUM>, the method further includes step <NUM>.

In step <NUM>, a temperature correction coefficient is calculated based on the temperature of the friction plate.

In a practical application, there is a correspondence between a friction coefficient of the friction plate and the temperature of the friction plate. Calculating the temperature correction coefficient based on the temperature of the friction plate may improve accuracy in calculating the output torque. The temperature correction coefficient may be calibrated based on an actual vehicle condition, so as to improve accuracy of the temperature correction coefficient.

In step <NUM>, a temperature-compensated output torque is obtained based on the calculated output torque and the temperature correction coefficient.

In a practical application, the temperature-compensated output torque may be obtained by multiplying the calculated output torque by the temperature correction coefficient. Compared to the calculated output torque, the temperature-compensated output torque considers the influence of the temperature of the friction plate on the actual output torque, so that accuracy in calculating the actual output torque is improved, and the cases of excessive or inadequate output torque for the vehicle may be avoided.

In step <NUM>, a drag torque is calculated based on the front-rear shaft speed difference.

In a practical application, the actual output torque further includes a drag torque caused by the front-rear shaft speed difference. Taking the drag torque into account may further improve the accuracy in calculating the actual output torque and improve accuracy in controlling the vehicle.

In step <NUM>, the actual output torque is obtained based on the drag torque and the temperature-compensated output torque.

Based on the above steps, the actual output torque with high accuracy may be obtained as a sum of the drag torque and the temperature-compensated output torque, which improves accuracy in controlling the output torque by the vehicle.

With the method for intelligent four-wheel drive control described in the embodiment of the present invention, a temperature of the friction plate and a drag torque may be calculated based on the front-rear shaft speed difference; a temperature-compensated output torque is obtained based on the temperature of the friction plate; an actual output torque is obtained based on the drag torque and the temperature-compensated output torque. In this way, the actual output torque is obtained by compensating the calculated output torque according to the temperature of the friction plate and then combining with the drag torque, and therefore control accuracy of the actual output torque is improved, providing maneuverability of the vehicle and an ability of the vehicle to get out of trouble. In addition, by transmitting an overheat protection signal to the vehicle, probability of ablation damage to the friction plate is reduced, and a service life of the friction clutch is increased.

It should be noted that, for purpose of description, the method embodiments are expressed as a series of actions. However, those skilled in the art should appreciate that the present invention is not limited to the described order of the actions, and according to the present invention, some steps may be performed in another sequence or performed simultaneously. In addition, those skilled in the art should also understand that embodiments described in the specification are preferred embodiments, and the described actions are not necessitated for the embodiments of the present invention.

<FIG> is a structural block diagram of a system for intelligent four-wheel drive control according to an embodiment of the present invention. As shown in <FIG>, the system for intelligent four-wheel drive control is mainly applied to a vehicle, and includes an acquisition module <NUM>, a torque calculation module <NUM>, a temperature calculation module <NUM> and a torque control module <NUM>. The acquisition module <NUM> is connected to the torque calculation module <NUM> and the temperature calculation module <NUM>. The torque calculation module <NUM> is connected to the temperature calculation module <NUM> and the torque control module <NUM>.

<FIG> is a schematic diagram of a control process of a system for intelligent four-wheel drive control according to an embodiment of the present invention. As shown in <FIG>, the acquisition module <NUM> is configured to acquire vehicle condition information <NUM> of a vehicle, where the vehicle condition information <NUM> includes a front wheel speed and a rear wheel speed. In a practical application, the vehicle condition information <NUM> further includes vehicle speed, steering wheel angle signal, gear signal, engine torque, ambient temperature, shutdown time, gear ratios of gearbox, rolling radius, wheelbase, ratio of turning angle, and the like.

The torque calculation module <NUM> is configured to calculate a calculated output torque <NUM> based on the vehicle condition information <NUM>. In an example, the torque calculation module <NUM> may be configured to calculate the calculated output torque <NUM> based on the wheel speed, engine torque, gear signal and angle signal, and the like, of the vehicle.

The temperature calculation module <NUM> is configured to calculate a temperature <NUM> of the friction plate of the vehicle based on the front wheel speed, the rear wheel speed and the calculated output torque <NUM>.

In an example, the temperature calculation module <NUM> is configured to calculate a front-rear shaft speed difference <NUM> based on the front wheel speed and the rear wheel speed, and calculate a friction plate heat generation <NUM> of the vehicle based on the front-rear shaft speed difference <NUM> and the calculated output torque <NUM>. In a practical application, the friction plate heat generation <NUM> is related to not only the calculated output torque <NUM>, but also friction plate heat generation cause by the front-rear shaft speed difference <NUM>. In the embodiment of the present invention, the front-rear shaft speed difference <NUM> is considered when calculating the friction plate heat generation <NUM>, so that accuracy in calculating the temperature <NUM> of the friction plate is improved.

In the embodiment of the present invention, a friction plate heat dissipation <NUM> is calculated based on the friction plate heat generation <NUM>. In an example, the temperature calculation module <NUM> is further configured to acquire a historical temperature of oil where the friction plate is disposed, calculate the friction plate heat dissipation <NUM> based on the historical temperature, and calculate the temperature <NUM> of the friction plate based on the friction plate heat generation <NUM> and the friction plate heat dissipation <NUM>.

<FIG> is a schematic diagram of a calculation model for calculating a temperature of the friction plate, included in the temperature calculation module, according to an embodiment of the present invention. As shown in <FIG>, the front-rear shaft speed difference <NUM> and the calculated output torque <NUM> are inputted. A correction coefficient is obtained based on the front-rear shaft speed difference <NUM> through a functional calculation. For example, the correction coefficient is selected by applying the <NUM>-D lookup table function in Matlab (known as a registered trademark for a software). The correction coefficient is multiplied by the calculated output torque <NUM> to obtain a friction plate input torque that actually acts on the friction plate. The friction plate input torque is multiplied with the front-rear shaft speed difference <NUM> to obtain a work done by sliding friction, which is a main source of the friction plate heat generation <NUM>. The friction plate heat dissipation <NUM> is then subtracted from the work done by sliding friction to obtain a variation of the temperature <NUM> of the friction plate. The temperature <NUM> of the friction plate may be obtained by performing integration on the variation.

After the temperature <NUM> of the friction plate is obtained, according to the embodiment of the present invention, the torque calculation module <NUM> is further configured to correct the calculated output torque <NUM> according to the temperature <NUM> of the friction plate to obtain an actual output torque <NUM>.

In an example, the torque calculation module <NUM> is further configured to: calculate a temperature correction coefficient based on the temperature <NUM> of the friction plate; obtain a temperature-compensated output torque <NUM> based on the calculated output torque <NUM> and the temperature correction coefficient; calculate a drag torque <NUM> based on the front-rear shaft speed difference <NUM>; and obtain the actual output torque <NUM> based on the drag torque <NUM> and the temperature-compensated output torque <NUM>.

In a practical application, <FIG> is a schematic diagram of a calculation model in a torque calculation module according to an embodiment of the present invention. As shown in <FIG>, the torque calculation module <NUM> includes two portions: a correction on the output torque calculation value <NUM> according to the temperature <NUM> of the friction plate; and a calculation of the drag torque <NUM> according to the front-rear shaft speed difference <NUM>. The temperature <NUM> of the friction plate and the front-rear shaft speed difference <NUM> are inputted into the torque calculation module <NUM>. A temperature correction coefficient is obtained through a functional calculation on the temperature <NUM> of the friction plate. For example, the temperature correction coefficient is selected by applying the <NUM>-D lookup table function in Matlab (known as a registered trademark for a software). The temperature correction coefficient may be calibrated based on an actual condition of the vehicle, so as to improve accuracy of the temperature correction coefficient. The temperature-compensated output torque <NUM> may be obtained by multiplying the calculated output torque <NUM> by the temperature correction coefficient. A sum of the temperature-compensated output torque <NUM> and the drag torque <NUM> is taken as the actual output torque <NUM>.

In a practical application, the front-rear shaft speed difference <NUM> needed for the torque calculation module <NUM> may be obtained by recalling the front-rear shaft speed difference <NUM> calculated in the temperature calculation module <NUM>, or may be calculated based on the front wheel speed and the rear wheel speed, which is not limited herein.

In the embodiment of the present invention, a Proportion-Integral-Differential (PID) feedback is established between the actual output torque <NUM> and the calculated output torque <NUM> to adjust magnitude of the input signal, so as to improve accuracy of the output torque of the system for intelligent four-wheel drive control, and improve maneuverability of the vehicle, an ability of the vehicle to get out of trouble, and a Noise-Vibration-Harshness (NVH ) performance.

In the embodiment of the present invention, the torque control module <NUM> is configured to control a friction clutch to output the actual output torque <NUM>, to meet an actual need of the vehicle. In an example, the torque control module <NUM> may be configured to: obtain, based on the calculated actual output torque <NUM>, a current required for the friction clutch; and control, by using the current, the friction clutch to output the actual output torque <NUM>. In this way, probability of ablation damage to the friction plate is reduced while meeting the actual needs of the vehicle.

In the embodiment of the present invention, based on that the temperature <NUM> of the friction plate is obtained, the temperature calculation module <NUM> is further configured to calculate, based on the friction plate heat dissipation <NUM>, the vehicle speed and the ambient temperature, a current oil temperature <NUM> of the oil where the friction plate is disposed.

In an example, the friction plate heat dissipation <NUM> is used for calculating an oil-absorbed temperature <NUM>; and the vehicle speed and the ambient temperature are used for calculating an oil heat dissipation <NUM>. The current oil temperature <NUM> is obtained by subtracting the oil heat dissipation <NUM> from the oil-absorbed temperature <NUM>.

<FIG> is a schematic diagram of a calculation model for calculating a current oil temperature, included in a temperature calculation module, according to an embodiment of the present invention. As shown in <FIG>, an input signal for the temperature calculation module <NUM> includes the oil-absorbed temperature <NUM> and the vehicle condition information <NUM>. The vehicle condition information <NUM> specifically includes vehicle speed and ambient temperature. A correspondence between the vehicle speed and ambient temperature and the oil heat dissipation <NUM> is pre-stored in the temperature calculation module <NUM>. For example, the oil heat dissipation <NUM> corresponding to a present vehicle speed and ambient temperature may be obtained by applying a <NUM>-D lookup table function in Matlab (known as a registered trademark for a software); then a difference between the oil-absorbed temperature <NUM> and the oil heat dissipation <NUM> is calculated; the difference is divided by a specific heat capacity of the oil to obtain a variation of oil temperature; and the current oil temperature <NUM> is obtained by performing integration on the variation of the oil temperature.

In the embodiment of the present invention, the system for intelligent four-wheel drive control further includes an overheat protection module <NUM>. The overheat protection module <NUM> is connected to the temperature calculation module <NUM>. The overheat protection module <NUM> is configured to transmit an overheat protection signal to the vehicle when the temperature <NUM> of the friction plate meets a first preset condition and /or when the current oil temperature <NUM> meets a second preset condition.

Specific description of the first preset condition and the second preset condition is provided in detail in the second embodiment, and is not repeated herein.

<FIG> is a schematic diagram of a calculation model in an overheat protection module according to an embodiment of the present invention. As shown in <FIG>, an input signal for the overheat protection module <NUM> includes the temperature <NUM> of the friction plate and the current oil temperature <NUM>. The temperature <NUM> of the friction plate is compared with the first preset condition, and the current oil temperature <NUM> is compared with the second preset condition. An overheat protection signal is transmitted to the vehicle when the temperature of the friction plate <NUM> meets the first preset condition and /or when the current oil temperature <NUM> meets the second preset condition. The vehicle enters an overheat protection mode and sends an overheat signal to the vehicle. An instrument in the vehicle receives and displays the overheat protection signal, or, an indicator light in the vehicle issues an overheat protection warning, in order to remind a driver to decelerate the vehicle. The intelligent four-wheel drive system automatically terminates the overheat protection mode in case that the temperature of the friction plate <NUM> does not meet the first preset condition and the current oil temperature <NUM> does not meet the second preset condition.

With the overheat protection module in the embodiment of the present invention, an automatic protection capability of the intelligent four-wheel drive system when overloaded is improved, which extends a service life of the friction clutch.

In practical applications, the acquisition module <NUM>, the torque calculation module <NUM>, the temperature calculation module <NUM>, the torque control module <NUM> and the overheat protection module <NUM> are all integrated in an electronic control unit of the intelligent four-wheel drive system, and the multiple modules operate in parallel to improve calculation speed and reduce time consumed in calculation.

In summary, the system for intelligent four-wheel drive control according to the embodiment of the present invention has at least the following advantages.

With the system for intelligent four-wheel drive control described in the embodiment of the present invention, a calculated output torque of a vehicle may be calculated based on vehicle condition information of the vehicle; then a front-rear shaft speed difference is calculated based on a front wheel speed and a rear wheel speed; a temperature of the friction plate of the vehicle may be calculated based on the front-rear shaft speed difference and the calculated output torque; and an actual output torque is obtained by correcting the calculated output torque based on the temperature of the friction plate, and a friction clutch of the vehicle is controlled to output the actual output torque. In the system for intelligent four-wheel drive control provided in the embodiments of the present invention, the temperature of the friction plate is directly obtained based on real-time vehicle condition information, and thereby has higher accuracy; in addition, the calculated output torque is corrected according to the temperature of the friction plate, which improves accuracy in controlling the output torque, thereby improving maneuverability of the vehicle and an ability of the vehicle to get out of trouble, and reducing probability of ablation damage to the friction plate.

Device embodiments, which are similar to the method embodiments, are described briefly, and reference may be made to the description of the method embodiments.

A vehicle is further provided in the embodiments of the present invention. The vehicle includes the system for intelligent four-wheel drive control according to the embodiments. Specific structure and general principles of the system for intelligent four-wheel drive control are described in detail in the aforementioned embodiments, which are not repeated herein.

In the vehicle provided by the embodiment of the present invention, with the system for intelligent four-wheel drive control, a temperature of the friction plate may be directly obtained based on real-time vehicle condition information, and a calculated output torque may be corrected based on the temperature of the friction plate, so that accuracy in controlling the output torque is improved, and in turn maneuverability of the vehicle and an ability of the vehicle to get out of trouble are improved, and probability of ablation damage to the friction plate is reduced.

The device embodiments described above are merely illustrative. A unit described as a discrete component may be or may not be physically separated. Components shown as units may be or may not be physical units, that is, the components may be located in one place or may be distributed onto multiple networked units. All of or part of the units may be selected based on actual needs to implement the solutions according to the embodiments of the invention. Those skilled in the art may understand and practice the present invention without any creative effort.

Various component embodiments of the present invention may be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. Those skilled in the art should understand that a microprocessor or a digital signal processor (DSP) may be used in practice to implement some or all functions of some or all components in the computing device according to the embodiments of the present invention. The present invention may alternatively be implemented as a device or program (such as a computer program and computer program product) for performing part or all of the methods described herein. Such program for implementing the present invention may be stored on a computer-readable medium, or may be in a form of one or more signals. Such signals may be downloaded from Internet sites, or provided on carrier signals, or in any other form.

For example, <FIG> shows a computing device configured to perform the method according to the present invention. The computing device traditionally includes a processor <NUM> and a computer program product or computer readable medium in a form of a memory <NUM>. The memory <NUM> may be an electronic memory such as flash memory, Electrically Erasable Programmable Read Only Memory (EEPROM), Electrically Programmable Read-Only-Memory (EPROM), hard disk, or Read-Only-Memory (ROM). The memory <NUM> has storage space <NUM> for storing program codes <NUM> for performing any of the steps in the above method. For example, the storage space <NUM> for storing the program codes may include various program codes <NUM> for implementing various steps in the above methods. The program coded may be read from or written into one or more computer program products. The computer program product includes hard disk, compact disk (CD), memory card, floppy disk or other carriers for storing program codes. The computer program product is typically a portable storage unit or a fixed storage unit, as described with reference to <FIG>. The storage unit may have storage segments, storage spaces, and the like, arranged similarly to the memory <NUM> in the computing device in <FIG>. The program codes may be compressed in a suitable form, for example. Typically, the storage unit includes computer readable codes <NUM>', readable by a processor such as the processor <NUM>, for example. The codes, when being executed by a computing device, cause the computing device to perform the steps of the method described above.

As used herein, terms of "an embodiment," "embodiments" or "one or more embodiments" indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. In addition, it should be noted that instances of "in an embodiment" herein do not necessarily refer to a same embodiment.

Numerous specific details are set forth in the description provided herein. It should be understood, however, that embodiments of the present invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail in order to avoid obscuring understanding of the description.

Claim 1:
A method for intelligent four-wheel drive control, comprising:
acquiring (<NUM>, <NUM>) vehicle condition information of a vehicle, wherein the vehicle condition information comprises a front wheel speed of the vehicle and a rear wheel speed of the vehicle;
calculating (<NUM>, <NUM>), based on the vehicle condition information, a calculated output torque;
calculating (<NUM>), based on the front wheel speed, the rear wheel speed and the calculated output torque, a temperature of a friction plate of the vehicle;
correcting (<NUM>) the calculated output torque according to the temperature of the friction plate, to obtain an actual output torque; and
controlling (<NUM>, <NUM>) a friction clutch to output the actual output torque,
wherein the step of calculating (<NUM>), based on the front wheel speed, the rear wheel speed and the calculated output torque, a temperature of the friction plate of the vehicle comprises:
calculating (<NUM>) a front-rear shaft speed difference from the front wheel speed and the rear wheel speed; and
calculating the temperature of the friction plate of the vehicle based on the front-rear shaft speed difference and the calculated output torque,
characterized in that
the step of calculating the temperature of the friction plate of the vehicle based on the front-rear shaft speed difference and the calculated output torque comprises:
calculating (<NUM>) a friction plate heat generation of the vehicle based on the front-rear shaft speed difference and the calculated output torque;
acquiring (<NUM>) a historical temperature of oil where the friction plate is disposed;
calculating (<NUM>) a friction plate heat dissipation based on the historical temperature; and
calculating (<NUM>) the temperature of the friction plate based on the friction plate heat generation and the friction plate heat dissipation.