Control device for four-wheel drive vehicle and control method thereof

Abstract

Disclosed are a control device for a four-wheel drive vehicle and a control method thereof. The present embodiment can implement an optimal driving condition in various situations occurring in vehicles equipped with different types of tires.

Description

Control device for a four-wheel drive vehicle and its control method

[0001] The present invention relates to the driving stability of a vehicle equipped with different types of tires, and more specifically, to a control device for a four-wheel drive vehicle and a control method thereof.

[0002] Generally, a four-wheel drive vehicle is a vehicle that can drive all four wheels, unlike a two-wheel drive vehicle that drives only the front or rear wheels.

[0003] Compared to two-wheel drive vehicles, it has superior propulsion power because all four wheels are driven simultaneously, and it is characterized by excellent driving performance on rough roads such as unpaved roads, roads with very steep slopes, and roads with slippery surfaces.

[0004] However, the above four-wheel drive vehicle had problems such as poor fuel efficiency and high noise when driven on general roads that do not apply a lot of load during normal driving.

[0005] Therefore, four-wheel drive vehicles are generally driven by two wheels during normal driving, but are driven by four wheels on rough roads, slippery surfaces, and sections requiring high propulsion power, thereby improving fuel efficiency and reducing noise and vibration.

[0006] In this way, in the past, the distribution of driving force in the above four-wheel drive vehicle was limited to switching from four-wheel drive to two-wheel drive, and this was also done mechanically by the driver's operation.

[0007] However, recently, the distribution of driving force in these four-wheel drive vehicles is done electronically, and not only can it change from four-wheel drive to two-wheel drive, but it can also change the ratio of driving force distribution between the front and rear wheels depending on the situation, and in particular, when wheel slip occurs, the distribution of driving force can be controlled to vary depending on the degree of slip.

[0008] There's a problem with four-wheel drive systems: if one of the front or rear wheels is fitted with a tire of a different type, with a relatively smaller radius, the other wheel rotates faster than the wheel with the different tire. This causes the propeller shaft and the rear axle of a front-wheel-drive vehicle to rotate at different speeds, causing persistent slippage in the clutch within the coupling that controls the transmission of driving force from the propeller shaft to the rear axle.

[0009] When the vehicle is driven in two-wheel drive, the clutch remains in a non-contact state, so the coupling does not overheat. However, when different types of tires are installed on the vehicle and the wheel speeds of the front and rear wheels are different, the vehicle determines that slip has occurred between the current tires and the road surface and enters four-wheel drive mode, causing the clutch to come into frictional contact, and slipping of the clutch occurs in the frictional contact state due to different rotational speeds between the propeller shaft and the rear axle shaft.

[0010] If the clutch inside the coupling is in friction contact and the driving power is transmitted to the rear wheels for a short period of time when the vehicle is in 4-wheel drive mode, there may not be a major problem. However, in the case of long-term constant-speed driving such as on the highway, the clutch is in a state of friction contact continuously, causing the clutch to slip for a long time, overheating the clutch, and the torque is continuously transmitted excessively, which eventually causes the coupling and surrounding driving parts to overheat and be damaged.

[0011] In addition, since the conditions for detecting different types of tires were not clear in the past, it was difficult to identify the cause of the slip phenomenon, and thus a solution was needed.

[0012] Embodiments of the present invention aim to provide a control device for a four-wheel drive vehicle and a control method thereof capable of calculating the amount of slip to realize an optimal driving state even when slip occurs due to the influence of a road surface or harsh driving, or due to the installation of different types of tires or driving road surface conditions.

[0013] A control device for a four-wheel drive vehicle according to one embodiment of the present invention includes a driving state detection control unit (100) that detects the current driving state of the vehicle and determines whether different types of tires are mounted; a slip determination control unit (200) that determines a slip state of the different types of tires when it is determined that the vehicle is mounted with different types of tires; a level selection control unit (300) that sets the level of the different types of tires according to slip amount data calculated by the slip determination control unit; a driving distance calculation control unit (400) that calculates a driving distance according to the level of the different types of tires; and a torque control unit (500) that controls torque output to a driving shaft according to the level of the different types of tires.

[0014] The above driving state detection control unit (100) includes a first driving state detection unit (110) that detects the driving environment of different types of tires; a second driving state detection unit (120) that detects whether the driver is currently driving stably; and a third driving state detection unit (130) that detects the lateral movement safety state of the vehicle.

[0015] The above first driving status detection unit (110) detects the wheel speed change amount of each wheel, wheel speed for each driving mode, lateral acceleration, vehicle driving distance, and transmission output torque.

[0016] The above second driving state detection unit (120) detects the steering angle speed and acceleration amount.

[0017] The third driving state detection unit (130) detects the steering angle and yaw rate.

[0018] The above driving status detection unit (100) determines whether a different type of tire is installed only when the data detected by the first to third driving status detection units (110, 120, 130) satisfies the reference value.

[0019] The above slip judgment control unit (200) calculates the average slip amount of the left and right wheel slip amounts of the front and rear wheels, and the average wheel slip amount of the front and rear wheels, respectively.

[0020] The above level selection control unit (300) calculates the slip amount for a predetermined period of time, and selects different levels depending on the degree of error in the driving system rotation axis caused by different tires or road conditions.

[0021] The above level selection control unit (300) classifies the levels of different tires from level zero (LV 0) to level 1 (LV 1), level 2 (LV 2), and level 3 (LV 3).

[0022] The above level zero (LV 0) corresponds to a case where the slip amount is less than the first limit value.

[0023] The above level 1 (LV 1) is characterized in that the slip amount is between the second limit value and the third limit value.

[0024] The above level 2 (LV 2) corresponds to a slip amount between the third limit value and the fourth limit value.

[0025] The above level 3 (LV 3) applies when the average slip amount is greater than the fourth limit value.

[0026] The above level selection control unit (300) compares and determines the slip amount of different types of tires detected while the actual vehicle is driving with the slip amount of different types of tires stored in the memory unit, and then calculates the slip amount occurring in the clutch by considering the drivetrain gear ratio.

[0027] The above torque control unit (500) controls the drive system 4-wheel drive torque output to 100% when level zero (LV 0) is present.

[0028] The above torque control unit (500) controls the drive system 4-wheel drive torque output to the first output value when at level 1 (LV 1).

[0029] The above torque control unit (500) controls the drive system 4-wheel drive torque output to a second output value when at level 2 (LV 2).

[0030] The above torque control unit (500) controls the drive system to release the four-wheel drive when at level 3 (LV 3) and controls the fault code or warning light to turn on.

[0031]

[0032] A control method for a four-wheel drive vehicle according to one embodiment of the present invention includes a first step (ST100) of detecting a current driving state of the vehicle and determining whether different types of tires are mounted; a second step (ST200) of determining a slip state of the different types of tires when it is determined that the vehicle is mounted with different types of tires; a third step (ST300) of setting a level of the different types of tires according to slip amount data calculated by the slip determination control unit; a fourth step (ST400) of calculating a driving distance according to the level of the different types of tires; and a fifth step (ST500) of controlling torque output for a driving shaft according to the level of the different types of tires.

[0033] The above first step (ST100) includes a first driving state detection step (ST110) for detecting whether driving status information satisfies a reference value; a second driving state detection step (ST120) for detecting whether the current driver is driving stably; and a third driving state detection step (ST130) for detecting the lateral movement safety status of the vehicle.

[0034] The above first step (ST100) determines whether a different type of tire is installed only when all of the above first to third driving status detection steps (ST110, ST120, ST130) are satisfied.

[0035] Embodiments of the present invention can maintain optimal driving conditions even when slipping occurs in a vehicle equipped with different types of tires.

[0036] Embodiments of the present invention can prevent problems caused by deformation and wear of drivetrain components in advance by calculating the slip amount of different tires using the relative speed of each wheel equipped on the vehicle, thereby stably maintaining durability and preventing failures caused by breakage.

[0037] FIG. 1 is a drawing showing the configuration of a control device of a four-wheel drive vehicle according to the present embodiment.

[0038] Fig. 2 is a drawing showing a detailed configuration of a driving state detection control unit according to the present embodiment.

[0039] Fig. 3 is a drawing showing a detailed configuration of a slip judgment control unit according to the present embodiment.

[0040] Fig. 4 is a diagram illustrating a state of calculating the clutch slip amount according to the present embodiment.

[0041] Fig. 5 is a drawing showing a detailed configuration of a level selection control unit according to the present embodiment.

[0042] Fig. 6 is a diagram showing a control state according to a different tire level by a torque control unit according to the present embodiment.

[0043] Fig. 7 is a flowchart illustrating a control method of a four-wheel drive vehicle according to the present embodiment.

[0044] The advantages and features of the present disclosure, and methods for achieving them, will become clearer with reference to the embodiments described below in detail with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below, but may be implemented in various different forms. These embodiments are provided solely to ensure that the disclosure is complete and to fully inform those skilled in the art of the scope of the disclosure, and the present disclosure is defined solely by the scope of the claims. Like reference numerals designate like elements throughout the specification.

[0045] When one component is referred to as being "connected to" or "coupled to" another component, it includes both cases where it is directly connected or coupled to the other component, or where there is another component intervening therebetween. Conversely, when one component is referred to as being "directly connected to" or "directly coupled to" another component, it indicates that there is no other component intervening therebetween. "And / or" includes each and any combination of one or more of the mentioned items.

[0046] The terminology used herein is for the purpose of describing embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular includes the plural unless the context clearly dictates otherwise. As used herein, the terms "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components, steps, operations, and / or elements.

[0047] Although terms like "first," "second," etc. are used to describe various components, these components are not limited by these terms. These terms are used only to distinguish one component from another.

[0048]

[0049] A control device for a four-wheel drive vehicle according to an embodiment of the present invention will be described with reference to the drawings. The attached FIG. 1 is a drawing showing the configuration of the control device for a four-wheel drive vehicle according to the embodiment, FIG. 2 is a drawing showing the detailed configuration of a driving state detection control unit according to the embodiment, FIG. 3 is a drawing showing the detailed configuration of a slip determination control unit according to the embodiment, and FIG. 4 is a drawing showing a state of calculating a clutch slip amount according to the embodiment.

[0050]

[0051] Referring to the attached drawings 1 to 4, a control device of a four-wheel drive vehicle according to the present embodiment is used to accurately determine the amount of slip in a vehicle when different tires having different radii are installed on either the front or rear wheels, and to prevent a failure due to clutch overheating or continuous excessive torque in the drivetrain system.

[0052] To this end, the present embodiment includes a driving state detection control unit (100) that detects the current driving state of a vehicle and determines whether a different type of tire is mounted, a slip determination control unit (200) that determines the slip state of the different type of tire when it is determined that the vehicle is mounted with a different type of tire, a level selection control unit (300) that sets the level of the different type of tire according to slip amount data calculated by the slip determination control unit, a driving distance calculation control unit (400) that calculates a driving distance according to the level of the different type of tire, and a torque control unit (500) for controlling torque output to a driving shaft according to the level of the different type of tire.

[0053]

[0054] The above driving state detection control unit (100) includes a first driving state detection unit (110) that detects the driving environment of different types of tires, a second driving state detection unit (120) that detects whether the current driver is driving stably, and a third driving state detection unit (130) that detects the lateral movement safety state of the vehicle.

[0055] The above driving state detection control unit (100) controls detection of different types of tires to occur only when all data detected by the first to third driving state detection units (110, 120, 130) satisfy the reference value.

[0056] If any of the data detected by the first to third driving state detection units (110, 120, 130) is unsatisfactory, the data is repeatedly detected again until all meet the standard value, thereby making an accurate judgment on whether or not different types of tires are installed.

[0057]

[0058] The above first driving state detection unit (110) detects the amount of change in wheel speed of each wheel, and detects whether the wheel speed for each driving mode satisfies a reference value, whether the lateral acceleration satisfies a reference value, whether the vehicle driving distance satisfies a reference value, and whether the transmission output torque satisfies a reference value. In this embodiment, the above-described data is required for stable driving of the vehicle when changing from two-wheel drive to four-wheel drive.

[0059] For example, when a vehicle is driven at a constant speed for extended periods, such as on a highway, the wheel speed of each wheel is detected within a certain range. Furthermore, unlike city driving, the vehicle's lateral acceleration remains constant without abrupt changes when driving steadily in a specific lane for extended periods.

[0060] In addition, since the above driving distance is a long-distance drive on a highway rather than a short distance, data is needed to determine whether different types of tires are installed.

[0061] The above transmission output torque is maintained for a long time while maintaining a specific gear on the highway, so if all of the detailed conditions above are satisfied, it is detected as a stable driving state.

[0062] The driving state detection control unit (100) determines that the vehicle is driving in a stable driving state when all data detected by the first driving state detection unit (110) satisfies the reference value.

[0063]

[0064] The second driving state detection unit (120) detects whether the steering angle speed satisfies a reference value and whether the acceleration amount satisfies a reference value to determine whether the driver is driving stably. If the steering angle changes excessively or the acceleration amount suddenly increases, it is defined as not driving stably.

[0065] The third driving state detection unit (130) determines that lateral stability is satisfied when the steering angle and yaw rate satisfy the reference values.

[0066] The above driving status detection unit (100) determines whether a different type of tire is installed only when the data detected by the first to third driving status detection units (110, 120, 130) satisfies the reference value.

[0067]

[0068] *

[0069] The above slip judgment control unit (200) calculates the average slip amount of the left and right wheel slip amounts of the front and rear wheels, and the average wheel slip amount of the front and rear wheels, respectively.

[0070] For example, the slip judgment control unit (200) receives data on the speed of the right wheel of the front wheel, the speed of the left wheel of the front wheel, the speed of the right wheel of the rear wheel, and the speed of the left wheel of the rear wheel, and calculates the average slip amount using the data on the slip of the left and right wheels of the front wheel and the slip of the left and right wheels of the rear wheel.

[0071] Additionally, the average slip of the front and rear wheels is calculated using the front wheel average wheel slip data and the rear wheel average wheel slip data.

[0072] The above slip determination control unit (200) can calculate the slip amount of different types of tires using the front wheel left and right and rear wheel left and right average slip data and the front wheel and rear wheel average slip data.

[0073]

[0074] Referring to the attached drawings 5 ​​and 6, the level selection control unit (300) according to the present embodiment calculates the slip amount when a different tire detection allowance signal is input for a predetermined period of time, and selects different levels depending on the degree of occurrence of a corresponding diameter error of the drivetrain rotation axis due to different tires or road surface conditions.

[0075] The above level selection control unit (300) classifies the levels of different tires from level zero (LV 0) to level 1 (LV 1), level 2 (LV 2), and level 3 (LV 3). It is defined that the slip amount increases as it goes from level zero (LV 0) to level 3 (LV 3).

[0076] The above level zero (LV 0) corresponds to a case where the amount of slip is less than the first limit value, a state in which almost no slip occurs in the awning, and a state in which the driver actually hardly feels it.

[0077] The above Level 1 (LV 1) corresponds to a state where the amount of slip is between the second limit value and the third limit value, and some slip occurs due to different tires while the vehicle is currently driving, and some drivers may perceive that the vehicle's behavior is not ideal.

[0078] The above Level 2 (LV 2) corresponds to a state in which the slip amount is between the third limit value and the fourth limit value, and the slip caused by different tires while the vehicle is currently driving is greater than Level 1, and most drivers can judge that the vehicle is driving unstably.

[0079] The above Level 3 (LV 3) corresponds to a situation where the average slip amount is greater than the fourth limit value, and the slip caused by different tires while the vehicle is currently driving is greater than Level 2. The above Level 3 may cause safety issues when the vehicle is driven for a long period of time.

[0080]

[0081] The above level selection control unit (300) compares and determines the slip amount of different types of tires detected while the actual vehicle is driving with the slip amount of different types of tires stored in the memory unit, and then calculates the slip amount occurring in the clutch by considering the drivetrain gear ratio.

[0082] The above clutch slip amount requires unit conversion before calculating the clutch slip amount.

[0083]

[0084] The above driving distance calculation control unit (400) performs calculation after maintaining the heterogeneous tire detection allowance time for a certain period of time.

[0085] For example, when the rotation axis radial error level changes, the driving distance before entering the level is set to be the same as the odometer driving distance.

[0086] When the above-mentioned heterogeneous tire level is changed to level 1, level 2, or level 3, the driving distance after entering the level is calculated by subtracting the driving distance before entering the level from the driving distance on the odometer while maintaining the level, and the final driving distance is calculated by subtracting the driving distance after entering the level from the accumulated driving distance of the level stored in the EEPROM.

[0087]

[0088] The torque control unit (500) according to this embodiment controls the four-wheel drive torque output to 100% when level zero (LV 0) is reached, and no separate failure signal is generated.

[0089] The above torque control unit (500) controls the drive system 4-wheel drive torque output to a first output value when at level 1 (LV 1), and controls the drive system 4-wheel drive torque output to a second output value when at level 2 (LV 2).

[0090] The above torque control unit (500) can control the four-wheel drive to be released from the drive system when at level 3 (LV 3), and control the fault code or warning light to be turned on so that the driver can recognize it, thereby promoting safe driving.

[0091]

[0092] A method for controlling a four-wheel drive vehicle according to one embodiment of the present invention will be described with reference to drawings.

[0093] Referring to the attached drawing 7, the present embodiment includes a first step (ST100) of detecting the current driving state of a vehicle to determine whether a different type of tire is mounted, a second step (ST200) of determining a slip state of the different type of tire if it is determined that the vehicle is mounted with a different type of tire, a third step (ST300) of setting the level of the different type of tire according to slip amount data calculated by the slip determination control unit, a fourth step (ST400) of calculating a driving distance according to the level of the different type of tire, and a fifth step (ST500) of controlling torque output for a driving shaft according to the level of the different type of tire.

[0094] The above first step (ST100) includes a first driving status detection step (ST110) for detecting whether driving status information satisfies a reference value, a second driving status detection step (ST120) for detecting whether the current driver is driving stably, and a third driving status detection step (ST130) for detecting the lateral movement safety status of the vehicle.

[0095]

[0096] The above first driving state detection step (ST110) detects the amount of change in wheel speed of each wheel, and detects whether the wheel speed for each driving mode satisfies a reference value, whether the lateral acceleration satisfies a reference value, whether the vehicle driving distance satisfies a reference value, and whether the transmission output torque satisfies a reference value. In this embodiment, the above-mentioned data is required for stable driving of the vehicle when changing from two-wheel drive to four-wheel drive.

[0097] For example, when a vehicle is driven at a constant speed for extended periods, such as on a highway, the wheel speed of each wheel is detected within a certain range. Furthermore, unlike city driving, the vehicle's lateral acceleration remains constant without abrupt changes when driving steadily in a specific lane for extended periods.

[0098] In addition, since the above driving distance is a long-distance drive on a highway rather than a short distance, data is needed to determine whether different types of tires are installed.

[0099] The above transmission output torque is maintained for a long time while maintaining a specific gear on the highway, so if all of the detailed conditions above are satisfied, it is detected as a stable driving state.

[0100] The above first step (ST100) determines that the vehicle is driving in a stable driving state if all data detected in the above first driving state detection step (ST110) satisfies the reference value.

[0101]

[0102] The second driving condition detection step (ST120) detects whether the steering angle and acceleration meet a reference value to determine whether the driver is driving stably. If the steering angle changes excessively or the acceleration suddenly increases, stable driving is defined as not being achieved.

[0103] The third driving state detection step (ST130) above determines that lateral stability is satisfied when the steering angle and yaw rate satisfy the reference values.

[0104] The above first step (ST100) determines whether a different type of tire is installed only when all of the above first to third driving status detection steps (ST110, ST120, ST130) are satisfied.

[0105]

[0106] The above second step (ST200) calculates the average slip amount of the left and right wheels of the front and rear wheels, and the average slip amount within the wheels of the front and rear wheels, respectively.

[0107] For example, the data on the speed of the right front wheel, the speed of the left front wheel, the speed of the right rear wheel, and the speed of the left rear wheel are input, and the average slip amount is calculated using the data on the slip of the left and right front wheels and the slip of the left and right rear wheels.

[0108] Additionally, the average slip of the front and rear wheels is calculated using the front wheel average wheel slip data and the rear wheel average wheel slip data.

[0109] The above second step (ST200) can calculate the slip amount of different tires using the front wheel left and right average slip data and the front wheel and rear wheel average slip data described above.

[0110]

[0111] The above third step (ST300) calculates the slip amount when a different tire detection allowance signal is input for a predetermined period of time, and different levels are selected depending on the degree of error in the driving system rotation axis caused by different tires or road conditions.

[0112] The above third step (ST300) classifies the levels of the heterogeneous tires from level zero (LV 0) to level 1 (LV 1), level 2 (LV 2), and level 3 (LV 3). It is defined that the slip amount increases as it goes from level zero (LV 0) to level 3 (LV 3) (see Fig. 5).

[0113] The above level zero (LV 0) corresponds to a case where the amount of slip is less than the first limit value, a state in which almost no slip occurs in the awning, and a state in which the driver actually hardly feels it.

[0114] The above Level 1 (LV 1) corresponds to a state where the amount of slip is between the second limit value and the third limit value, and some slip occurs due to different tires while the vehicle is currently driving, and some drivers may perceive that the vehicle's behavior is not ideal.

[0115] The above Level 2 (LV 2) corresponds to a state in which the slip amount is between the third limit value and the fourth limit value, and the slip caused by different tires while the vehicle is currently driving is greater than Level 1, and most drivers can judge that the vehicle is driving unstably.

[0116] The above Level 3 (LV 3) corresponds to a situation where the average slip amount is greater than the fourth limit value, and the slip caused by different tires while the vehicle is currently driving is greater than Level 2. The above Level 3 may cause safety issues when the vehicle is driven for a long period of time.

[0117]

[0118] The third step (ST300) above compares and determines the slip amount of different tires detected while the actual vehicle is driving with the slip amount of different tires stored in the memory, and then calculates the slip amount occurring in the clutch by considering the drivetrain gear ratio.

[0119] The above clutch slip amount requires unit conversion before calculating the clutch slip amount.

[0120]

[0121] The above fourth step (ST400) performs calculations after maintaining the heterogeneous tire detection allowance time for a certain period of time.

[0122] For example, when the rotation axis radial error level changes, the driving distance before entering the level is set to be the same as the odometer driving distance.

[0123] When the above-mentioned heterogeneous tire level is changed to level 1, level 2, or level 3, the driving distance after entering the level is calculated by subtracting the driving distance before entering the level from the driving distance on the odometer while maintaining the level, and the final driving distance is calculated by subtracting the driving distance after entering the level from the accumulated driving distance of the level stored in the EEPROM.

[0124]

[0125] The fifth step (ST500) according to this embodiment controls the four-wheel drive torque output to 100% when level zero (LV 0) is reached, and no separate failure signal is generated.

[0126] The above torque control unit (500) controls the drive system 4-wheel drive torque output to a first output value when at level 1 (LV 1), and controls the drive system 4-wheel drive torque output to a second output value when at level 2 (LV 2).

[0127] The above torque control unit (500) can control the four-wheel drive to be released from the drive system when at level 3 (LV 3), and control the fault code or warning light to be turned on so that the driver can recognize it, thereby promoting safe driving.

[0128]

[0129] Above, one embodiment of the present invention has been described, but a person having ordinary skill in the art will be able to modify and change the present invention in various ways by adding, changing, deleting or adding components, etc., within the scope that does not depart from the spirit of the present invention described in the claims, and this will also be considered to be included within the scope of the rights of the present invention.

[0130] The present embodiments can realize stable vehicle driving when equipped with heterogeneous tires.

Claims

1. A driving status detection control unit (100) that detects the current driving status of the vehicle and determines whether different types of tires are installed; A slip determination control unit (200) that determines the slip state of the different type of tire when it is determined that the vehicle is equipped with different type of tire; A level selection control unit (300) that sets the level of the heterogeneous tire according to the slip amount data calculated by the slip judgment control unit; A driving distance calculation control unit (400) that calculates the driving distance according to the level of the above-mentioned heterogeneous tires; and A control device for a four-wheel drive vehicle including a torque control unit (500) for controlling torque output to a driving axle according to the level of the above-mentioned heterogeneous tires.

2. In paragraph 1, The above driving condition detection control unit (100) includes a first driving condition detection unit (110) that detects the driving environment of different types of tires; A second driving status detection unit (120) that detects whether the current driver is driving stably; A control device for a four-wheel drive vehicle including a third driving state detection unit (130) that detects a lateral behavior safety state of the vehicle.

3. In paragraph 2, The above first driving state detection unit (110) is a control device of a four-wheel drive vehicle that detects the wheel speed change amount of each wheel, wheel speed by driving mode, lateral acceleration, vehicle driving distance, and transmission output torque.

4. In paragraph 2, The above second driving state detection unit (120) is a control device of a four-wheel drive vehicle that detects the steering angle speed and acceleration amount.

5. In paragraph 2, The above third driving state detection unit (130) is a control device of a four-wheel drive vehicle that detects the steering angle and yaw rate.

6. In paragraph 2, The above driving state detection unit (100) is a control device of a four-wheel drive vehicle that determines whether a different type of tire is installed only when the data detected by the first to third driving state detection units (110, 120, 130) satisfies a reference value.

7. In paragraph 1, The above slip judgment control unit (200) is a control device for a four-wheel drive vehicle that calculates the average slip amount of the left and right wheel slip amounts of the front and rear wheels, and the average slip amount within the wheels of the front and rear wheels, respectively.

8. In paragraph 1, The above level selection control unit (300) is a control device for a four-wheel drive vehicle that calculates the slip amount for a predetermined period of time and selects different levels depending on the degree of error in the driving system rotation axis caused by different tires or road conditions.

9. In paragraph 8, The above level selection control unit (300) is a control device of a four-wheel drive vehicle that classifies the levels of different tires from level zero (LV 0) to level 1 (LV 1), level 2 (LV 2), and level 3 (LV 3).

10. In paragraph 9, A control device for a four-wheel drive vehicle, characterized in that the above level zero (LV 0) corresponds to a case where the slip amount is less than a first limit value.

11. In paragraph 9, The above level 1 (LV 1) is a control device for a four-wheel drive vehicle, characterized in that the slip amount is between the second limit value and the third limit value.

12. In paragraph 9, The above level 2 (LV 2) is a control device for a four-wheel drive vehicle whose slip amount is between the third limit value and the fourth limit value.

13. In paragraph 9, The above Level 3 (LV 3) is a control device for a four-wheel drive vehicle that applies when the average slip amount is greater than the fourth limit value.

14. In paragraph 1, The above level selection control unit (300) is a control device for a four-wheel drive vehicle that calculates the slip amount occurring in the clutch by considering the drivetrain gear ratio after comparing and judging the slip amount of different tires detected while the vehicle is actually driving with the slip amount of different tires stored in the memory unit.

15. In paragraph 10, The above torque control unit (500) is a control device for a four-wheel drive vehicle that controls the four-wheel drive torque output of the drive system to 100% when the level is zero (LV 0).

16. In paragraph 11, The above torque control unit (500) is a control device of a four-wheel drive vehicle that controls the four-wheel drive torque output of the drive system to a first output value when it is at level 1 (LV 1).

17. In paragraph 12, The above torque control unit (500) is a control device of a four-wheel drive vehicle that controls the four-wheel drive torque output of the drive system to a second output value when at level 2 (LV 2).

18. In paragraph 13, The above torque control unit (500) is a control device of a four-wheel drive vehicle that controls the four-wheel drive to be disengaged from the drivetrain when at level 3 (LV 3) and controls a fault code or warning light to turn on.

19. The first step (ST100) detects the current driving status of the vehicle and determines whether different types of tires are installed; A second step (ST200) for determining the slip state of the different tires when it is determined that the vehicle is equipped with different tires; A third step (ST300) of setting the level of the different tires according to the slip amount data calculated in the above slip judgment control unit; Step 4 (ST400) for calculating the driving distance according to the level of the above-mentioned heterogeneous tires; and A control method for a four-wheel drive vehicle, comprising a fifth step (ST500) of controlling torque output to a driving axle according to the level of the above-mentioned heterogeneous tires.

20. In paragraph 19, The above first step (ST100) is a first driving status detection step (ST110) that detects whether the driving status information satisfies a reference value; The second driving status detection step (ST120) detects whether the current driver is driving stably; A control method for a four-wheel drive vehicle, comprising a third driving state detection step (ST130) for detecting a lateral behavior safety state of the vehicle.

21. In paragraph 20, A control method for a four-wheel drive vehicle in which the first step (ST100) determines whether different types of tires are installed only when all of the first to third driving state detection steps (ST110, ST120, ST130) are satisfied.

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