JP2009168079A - Vehicle motion control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle motion control system, capable of restricting deterioration of durability of drive force distribution control when traction control is carried out by drive force distribution control under such a situation that the wheel speed difference between the right and the left drive wheels tends to be large. <P>SOLUTION: The vehicle motion control system 1 is provided with a drive force distribution control device 2 to provide drive force to the right and the left drive wheels 11RR and 11RL, and control drive force distribution to the right and the left drive wheels 11RR and 11RL, and a brake force control device 3 to separately control brake force to the respective drive wheels 11RR and 11RL. In the vehicle motion control system 1, traction control is carried out to restrict slipping of the drive wheels 11RR and 11RL. When wheel speed difference between the right and the left drive wheels 11RR and 11RL is less than a specified threshold value, traction control by the drive force distribution control is carried out. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vehicle motion control system, and more particularly, durability of driving force distribution control when traction control by driving force distribution control is performed in a situation where a wheel speed difference between left and right driving wheels tends to be large. The present invention relates to a vehicle motion control system that can suppress deterioration of the vehicle.

  Recent vehicle motion control systems include a driving force distribution control device that can control the driving force distribution to the left and right drive wheels. This drive force distribution control device has a control differential, and controls the drive force distribution to the left and right drive wheels by actively providing a left-right difference in the differential output shaft speed (drive force distribution control).

  As a conventional vehicle motion control system related to this problem, a technique described in Patent Document 1 is known. A conventional vehicle motion control system (a vehicle left / right driving force adjusting device) transfers the driving force between the left and right rotating shafts between the left wheel rotating shaft and the right wheel rotating shaft in the vehicle. A driving force transmission control mechanism capable of adjusting the driving force of the left and right wheels is provided, and the driving force transmission control mechanism is connected to one of the left and right rotating shafts and is connected to the one rotating shaft side. Is interposed between the other rotating shaft side of the left and right rotating shafts and the output part side of the shifting mechanism. A transmission capacity variable control torque transmission mechanism capable of transmitting a driving force between the left and right rotating shafts when engaged, and a control means for controlling the engagement state of the transmission capacity variable control torque transmission mechanism. The rotational speed ratio of the left and right wheels is When the rotation speed on the output side of the speed mechanism and the rotation speed on the other rotating shaft side become larger than the changing boundary value, the engagement of the transmission capacity variable control type torque transmission mechanism is released. Control stop means for stopping the driving force transmission control is provided.

Japanese Patent No. 2848126

  Also, in recent vehicle motion control systems, control is performed to prevent tire slip when starting or accelerating the vehicle (traction control). In particular, when starting on a straddle road (running roads with different friction coefficients of the road surfaces contacting the tires of the left and right drive wheels 11RR and 11RL), control for suppressing wheel slip on the road surface side having a low friction coefficient (Straddle traction control). Such control is realized by the driving force distribution control device performing the driving force distribution control.

  However, in straddle traction control, since the driving force distribution control is performed when the wheel applied to the road surface side having a low friction coefficient slips, the wheel speed difference between the left and right driving wheels tends to increase. Then, when torque movement is performed in the driving force distribution control, the load on the driving force distribution control device becomes excessive, the durability of the driving force distribution control device deteriorates, and the driving force distribution control device is damaged. (Such as clutch wear or seizure).

  For this reason, in the conventional vehicle motion control system, traction control by the driving force distribution control is not performed in a situation where the wheel speed difference between the left and right driving wheels tends to be large, such as when starting on a crossing road.

  Therefore, the present invention has been made in view of the above, and the driving force distribution control is performed when the traction control by the driving force distribution control is performed in a situation where the wheel speed difference between the left and right driving wheels tends to increase. An object of the present invention is to provide a vehicle motion control system capable of suppressing deterioration in durability of the vehicle.

  In order to achieve the above object, the vehicle motion control system according to the present invention can apply driving force to the left and right driving wheels and control the driving force distribution to the left and right driving wheels (hereinafter referred to as driving force distribution control). A driving force distribution control device and a braking force control device capable of independently controlling the braking force of each driving wheel (hereinafter referred to as braking force control), and traction control for suppressing slippage of the driving wheel. In the vehicle motion control system to be performed, traction control by driving force distribution control is performed when a wheel speed difference between the left and right driving wheels is equal to or less than a predetermined threshold value.

  In this vehicle motion control system, when the wheel speed difference between the left and right drive wheels is equal to or less than a predetermined threshold, the drive wheel traction control (straddle traction control, hereinafter simply referred to as traction control) is performed. Is called. In such a configuration, the traction control is performed by the driving force distribution control in a situation where the wheel speed difference between the left and right driving wheels tends to be large, so that suitable vehicle motion control (for example, smooth start of the vehicle on a crossing road) There is an advantage that is realized. Further, since the driving force distribution control is performed when the wheel speed difference between the left and right driving wheels is equal to or less than a predetermined threshold value, there is an advantage that deterioration of the durability of the driving force distribution control device due to the wheel speed difference is suppressed. . For example, if the driving force distribution control (torque movement) is performed when the wheel speed difference exceeds a predetermined threshold (high differential), the durability of the driving force distribution control device may deteriorate.

  In the vehicle motion control system according to the present invention, when the wheel speed difference between the left and right drive wheels exceeds a predetermined threshold, traction control by drive force distribution control is prohibited.

  In this vehicle motion control system, there is an advantage that the deterioration of the durability of the driving force distribution control device due to the wheel speed difference of the driving wheels is suppressed.

  Further, the vehicle motion control system according to the present invention provides a wheel speed difference between the left and right drive wheels based on a wheel speed ratio between the left and right drive wheels and a predetermined numerical value relating to durability of the drive force distribution control device. Is less than or equal to a predetermined threshold.

  This vehicle motion control system has an advantage that it is properly determined whether or not the traction control by the driving force distribution control can be performed without deteriorating the durability of the driving force distribution control device.

  The vehicle motion control system according to the present invention is configured such that when the traction control by the driving force distribution control is performed and the wheel speed difference between the left and right driving wheels exceeds a predetermined threshold, the traction control by the driving force distribution control is performed. It is prohibited and switched to traction control by braking force control.

  In this vehicle motion control system, there is an advantage that the deterioration of the durability of the driving force distribution control device due to the wheel speed difference of the driving wheel is suppressed, and the advantage that the slip of the driving wheel is suppressed by the braking force distribution control. There is.

  Further, the vehicle motion control system according to the present invention provides a wheel speed difference between the left and right drive wheels based on a wheel speed ratio between the left and right drive wheels and a predetermined numerical value relating to durability of the drive force distribution control device. It is determined whether or not has exceeded a predetermined threshold.

  This vehicle motion control system has an advantage that it is properly determined whether or not the traction control by the driving force distribution control can be performed without deteriorating the durability of the driving force distribution control device.

  In the vehicle motion control system according to the present invention, both the driving force distribution control and the braking force distribution control are performed in parallel, and the traction control is performed.

  In this vehicle motion control system, there is an advantage that the motion of the vehicle can be controlled more suitably compared to a configuration in which traction control is performed by either driving force distribution control or braking force control.

  In addition, the vehicle motion control system according to the present invention drives the traction control when it is predicted that the wheel speed difference between the left and right driving wheels exceeds a predetermined threshold when the traction control by the driving force distribution control is performed. The traction control can be switched to both force distribution control and braking force distribution control.

  In this vehicle motion control system, if it is predicted that the wheel speed difference between the left and right drive wheels will exceed a predetermined threshold when traction control is performed only by driving force distribution control, traction control by only driving force distribution control is performed. A stepwise transition to traction control by braking force control is performed. In such a configuration, the traction control is more suitably performed as compared with the configuration in which the current traction control is directly switched to the traction control based only on the braking force control when the traction control based only on the driving force distribution control is performed. Thereby, there exists an advantage by which a smooth vehicle start is implement | achieved.

  In the vehicle motion control system according to the present invention, whether or not there is a large difference in the estimated value of the friction coefficient of the road surface contacting the left and right driving wheel tires, or the command output value to the engine is greater than a predetermined threshold value. It is foreseen whether or not the wheel speed difference between the left and right drive wheels exceeds a predetermined threshold based on the determination result of whether or not is greater.

  This vehicle motion control system has an advantage that traction control is suitably performed.

  In the vehicle motion control system according to the present invention, the command output value to the driving force distribution control device is gradually reduced by the traction control by both the driving force distribution control and the braking force distribution control, and the braking force control device The command output value gradually increases.

  This vehicle motion control system has an advantage that a gradual transition from traction control based only on driving force distribution control to traction control based on braking force control can be satisfactorily realized.

  Further, the vehicle motion control system according to the present invention is configured such that when the wheel speed difference between the left and right drive wheels exceeds a predetermined threshold when performing traction control by both driving force distribution control and braking force distribution control, The driving force distribution control is prohibited and switched to traction control by braking force distribution control.

  In this vehicle motion control system, even when a gradual transition from traction control based only on driving force distribution control to traction control based on braking force control is performed, the wheel speed difference between the left and right drive wheels is a predetermined value. When the threshold value is exceeded, the driving force distribution control is immediately prohibited. Thereby, there exists an advantage by which the deterioration of the durability of the driving force distribution control apparatus resulting from the wheel speed difference of a driving wheel is suppressed.

  In the vehicle motion control system according to the present invention, when the wheel speed difference between the left and right drive wheels is equal to or less than a predetermined threshold value, the drive wheel traction control by the drive force distribution control (straddle traction control, hereinafter simply referred to as traction control). ) Is performed. In such a configuration, the traction control is performed by the driving force distribution control in a situation where the wheel speed difference between the left and right driving wheels tends to be large, so that suitable vehicle motion control (for example, smooth start of the vehicle on a crossing road) There is an advantage that is realized. Further, since the driving force distribution control is performed when the wheel speed difference between the left and right driving wheels is equal to or less than a predetermined threshold value, there is an advantage that deterioration of the durability of the driving force distribution control device due to the wheel speed difference is suppressed. . For example, if the driving force distribution control (torque movement) is performed when the wheel speed difference exceeds a predetermined threshold (high differential), the durability of the driving force distribution control device may deteriorate.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

  FIG. 1 is a block diagram showing a vehicle motion control system according to an embodiment of the present invention. FIG. 2 is a flowchart showing the operation of the vehicle motion control system shown in FIG.

[Vehicle motion control system]
The vehicle motion control system 1 controls the motion or behavior of the vehicle 10 (hereinafter referred to as vehicle motion control) to prevent the vehicle 10 from spinning, drifting out, wheel slipping, and the like. The vehicle motion control system 1 includes a driving force distribution control device 2, a braking force control device 3, and a control system 4 (see FIG. 1). In this embodiment, the left rear wheel 11RL and the right rear wheel 11RR of the vehicle 10 are drive wheels of the vehicle 10, and the left front wheel 11FL and the right front wheel 11FR are steering wheels of the vehicle 10.

  The driving force distribution control device 2 is a device that distributes the driving force to the left and right driving wheels 11 RR and 11 RL, and includes, for example, a control differential 21. In the driving force distribution control device 2, when the engine 12 generates driving force, the driving force is transmitted to the control differential 21 through the transmission (reduction gear) 13, the propeller shaft 14 and the viscous coupling 15. Then, this driving force is distributed to the left and right drive shafts 22RR, 22RL by the control differential 21, and transmitted to the drive wheels 11RR, 11RL. At this time, the distribution ratio of the driving force to the driving wheels 11RR and 11RL is controlled (driving force distribution control). In this embodiment, the driving force distribution control device 2 is disposed only on the rear wheels 11RR and 11RL of the vehicle 10. The vehicle motion control system 1 may be applied to a 2WD (two-wheel drive) vehicle or a 4WD (four-wheel drive) vehicle. For example, the driving force distribution control device 2 may be installed on the rear wheels of the 2WD vehicle (rear wheel drive), or the driving force distribution control device 2 may be installed only on the rear wheels of the 4WD vehicle.

  The braking force control device 3 is a device that controls the braking force applied to the wheels 11FR to 11RL, and includes a hydraulic circuit 31, wheel cylinders 32FR to 32RL, a brake pedal 33, and a master cylinder 34. The hydraulic circuit 31 includes a reservoir, an oil pump, various valves, and the like (not shown). The braking force control device 3 applies a braking force to the wheels 11FR to 11RL as follows. That is, (1) during normal operation, when the brake pedal 33 is depressed by the driver, the depression amount is transmitted to the hydraulic circuit 31 via the master cylinder 34. The hydraulic circuit 31 adjusts the hydraulic pressures of the wheel cylinders 32FR to 32RL, so that the wheel cylinders 32FR to 32RL are driven to apply a braking force (braking pressure) to the wheels 11FR to 11RL. On the other hand, at the time of (2) vehicle motion control, the target braking force for each wheel 11FR to 11RL is calculated based on the motion state of the vehicle, and the hydraulic circuit 31 is driven based on this target braking force, and each wheel cylinder 32FR to 32RL. Is controlled (braking force control).

  The control system 4 includes an ECU (Electronic Control Unit) 41, wheel speed sensors 42FR to 42RL that detect wheel speeds of the wheels 11FR to 11RL, a steering angle sensor 43 that detects a steering angle, and a yaw rate sensor that detects a yaw rate. 44, a longitudinal acceleration sensor 45 that detects longitudinal acceleration, a lateral acceleration sensor 46 that detects lateral acceleration, a vehicle speed sensor 47 that detects vehicle speed, an accelerator opening sensor 48, and a brake pedal force sensor 49. In the control system 4, the ECU 41 drives the engine 12, the driving force distribution control device 2, and the braking force control device 3 based on the detection results of the sensors 42 to 49. Thereby, total driving force control by the engine 12, driving force distribution control by the driving force distribution control device 2, and braking force control by the braking force control device 3 are performed, and vehicle motion control is performed.

[Vehicle motion control]
In this vehicle motion control system 1, the following vehicle motion control is performed in a situation where the wheel speed difference between the left and right drive wheels 11RR and 11RL is likely to increase (for example, when starting on a crossing road) (FIG. 2).

  First, it is determined whether or not traction control (TRC) is necessary (ST1). In this determination step ST1, a difference Vx−V between the wheel speed Vx and the vehicle body speed V is calculated for each drive wheel 11RR, 11RL, and the wheel speed Vx applied to any one of the drive wheels 11RR (11RL) and the vehicle body speed V are calculated. When the difference Vx−V exceeds a predetermined threshold (for example, 1.5 [m / s]), it is determined that traction control is necessary. The traction control generally refers to control for preventing tire slip when starting or accelerating the vehicle.

  If it is determined in this determination step ST1 that traction control is not necessary, the processing is terminated as it is.

  On the other hand, when it is determined in the determination step ST1 that traction control is necessary, it is determined whether or not the traction control is performed (ST2). In this determination step ST2, when the difference | VwRR−VwRL | between the wheel speeds VxRR and VxRL of the left and right drive wheels 11RR and 11RL exceeds a predetermined threshold (for example, 1.5 [m / s]), straddle traction It is determined that control is necessary. The straddle traction control refers to traction control that is performed on travel roads (straddle roads) having different friction coefficients of road surfaces that contact the tires of the left and right drive wheels 11RR and 11RL. In particular, in this embodiment, when the vehicle 10 starts, the traction control is performed, so that the slip of the drive wheels 11RR (11RL) contacting the road surface with a low coefficient of friction is suppressed, and the left and right drive wheels 11RR, The acceleration performance of the vehicle is improved by providing a difference in the driving force of 11RL.

  If it is determined in this determination step ST2 that straddle traction control is not necessary, traction control only by braking force control is performed (ST3). Specifically, traction control is performed by the braking force control device 3 controlling the braking force applied to the left and right drive wheels 11RR and 11RL. This prevents slipping of the drive wheels 11RR and 11RL. An existing technique can be adopted for traction control only by braking force control.

On the other hand, when it is determined in the determination step ST2 that the straddle traction control is necessary, it is determined whether or not the straddle traction control can be performed by the driving force distribution control (ST4). That is, it is determined whether or not the traction control by the driving force distribution control can be performed without deteriorating the durability of the driving force distribution control device 2. In this determination, the wheel speeds VxRR and VxRL ratio VxRR / VxRL and differential values ∇VxRR and ∇VxRL of the left and right drive wheels 11RR and 11RL are used. Note that the difference between the wheel speed at the previous control and the current wheel speed may be used as the differential values 車輪 VxRR and 前 回 VxRL of the wheel speed. This determination is performed as follows, for example. That is, when VxRR> VxRL, it is determined that the straddle traction control is performed by the driving force distribution control when the following formulas (1) and (2) are satisfied.

(VxRR + ∇VxRR) / (VxRL + ∇VxRL) <k1 (1)

VxRR / VxRL <k2 (2)

When VxRR <VxRL, it is determined that the straddle traction control is performed by the driving force distribution control when the following formulas (3) and (4) are satisfied.

(VxRL + ∇VxRL) / (VxRR + ∇VxRR) <k1 (3)

VxRL / VxRR <k2 (4)

K1 is a design numerical value (a numerical value defined by the durability of the clutch) of the driving force distribution control device 2 (control differential 21). Further, k2 is smaller than k1 (k1> k2), and is determined based on predetermined experimental data as a value for preventing early wear of the clutch.

  In this determination step ST4, when it is determined that the straddling traction control is not performed by the driving force distribution control, the straddling traction control only by the braking force control is performed (ST3).

  On the other hand, in the determination step ST4, when it is determined that the straddle traction control is performed by the driving force distribution control, the driving force distribution control device 2 performs the driving force distribution control and executes the traction control (ST5). ).

Specifically, first, (a) the force conversion values Fx_car and Fy_car are calculated based on the longitudinal acceleration Gx and the lateral acceleration Gy of the vehicle 10. Further, the command output value targetFx_low_μ of the drive wheel 11RR (11RL) on the road surface side having a low friction coefficient is calculated by the following equation (5). In Equation (5), N is the number of driving wheels (N = 2 in this embodiment).

targetFx_low_μ = SQRT (Fx_car ^ 2 + Fy_car ^ 2) / N (5)

Further, a command output value targetFx_high_μ to the drive wheels 11RL (11RR) on the road surface side having a high friction coefficient is calculated by the following equation (6).

targetFx_high_μ = targetFx_low_μ + AT + K (6)

At this time, the command output value targetFx_diff to the control differential 21 is represented by the following formula (7).

targetFx_diff = targetFx_high_μ−targetFx_low_μ = AT + K (7)

T is time. A is a constant for determining the speed at which the driving force difference is applied, and is calculated according to a predetermined matching condition. K is an allowable drive wheel difference at the time of executing the traction control, and is determined based on predetermined experimental data.

Further, (b) when executing the traction control, a difference VxRL-V (VxRR-V) between the wheel speed VxRL (VxRR) applied to the drive wheel 11RL (11RR) on the road surface side having a high friction coefficient and the vehicle body speed V is obtained. When a predetermined threshold value (for example, 1.5 [m / s]) is exceeded, the command output value targetFx_high_μ to the drive wheels 11RL (11RR) is fixed. Further, the command output value targetFx_diff to the control differential 21 is represented by the following formula (8).

targetFx_diff = targetFx_high_μ−targetFx_low_μ (8)

In both cases (a) and (b), the command output value targetFx_eng to the engine 12 is expressed by the following formula (9). In Equation (9), D is a reduction ratio in the control differential 21.

targetFx_eng = (targetFx_high_μ−targetFx_low_μ) / D (9)

  Next, when the traction control (ST5) based on the driving force distribution control is performed, the difference between the wheel speeds VxRR and VxRL of the left and right driving wheels 11RR and 11RL | VwRR−VwRL | affects the durability of the control differential 21. A plurality of prediction determinations are made (forecast determination steps ST6 and ST7).

First, in the first preview determination step ST6, it is determined whether or not the following condition (p) is satisfied. That is, when (p) VxRR> VxRL, the following formulas (10) and (11) are satisfied, or when VxRR <VxRL, the following formulas (12) and (13) are satisfied. Whether or not is satisfied is determined.

VxRR / VxRL> k3 (10)

(VxRR + ∇VxRR) / (VxRL + ∇VxRL) <k2 (11)

VxRL / VxRR> k3 (12)

(VxRL + ∇VxRL) / (VxRR + ∇VxRR) <k2 (13)

In Equations (10) to (13), k2 is the same as the numerical values used in Equations (2) and (4). Further, k3 is a value smaller than k2, and is set as a suitable value that does not terminate the driving force distribution control early.

  When this condition (p) is satisfied, it is considered that the difference | VwRR−VwRL | between the actual wheel speeds VxRR and VxRL is excessive. Therefore, the driving force distribution control (ST5) is immediately stopped, and straddle traction control is performed only by the braking force control (ST3). That is, the transition from the driving force distribution control to the braking force control is performed immediately. Thereby, deterioration of the durability of the control differential 21 due to the difference between the left and right wheel speeds is suppressed.

  On the other hand, when the condition (p) is not satisfied, the second preview determination step ST7 is performed. In this prediction determination step ST7, it is determined whether or not the next condition (q) or (r) is satisfied.

  In the determination of the condition (q), it is determined whether or not the command output value targetFx_diff to the control differential 21 is larger than a predetermined threshold value Fx_max_diff (targetFx_diff> Fx_max_diff). When this condition (q) is satisfied, the difference between the estimated values of the friction coefficients of the road surfaces in contact with the tires of the left and right drive wheels 11RR and 11RL is large, so the wheel speed VxRR when the drive wheels 11RR and 11RL slip. , VxRL difference | VwRR−VwRL | is considered to increase.

  On the other hand, in the determination of the condition (r), it is determined whether or not the command output value targetFx_eng to the engine 12 is larger than a predetermined threshold value Fx_max_eng (targetFx_eng> Fx_max_eng). When the condition (r) is satisfied, the command output value targetFx_eng to the engine 12 is large, so that the difference between the wheel speeds VxRR and VxRL when the drive wheels 11RR and 11RL slip | VwRR−VwRL | increases. It is done.

  If at least one of the above condition (p) or condition (q) is satisfied, there is currently a margin in the difference | VwRR−VwRL | between the wheel speeds VxRR and VxRL (the influence on the durability of the control differential 21 is affected). However, it is predicted that the difference | VwRR−VwRL | between the wheel speeds VxRR and VxRL will become excessive with time. Therefore, in such a case, a stepwise transition from straddling traction control based only on driving force distribution control to straddling traction control based on braking force control is performed (ST8). Therefore, the straddle traction control is more suitably performed as compared with the configuration in which the current straddle traction control (strand traction control only by driving force distribution control) is directly switched to straddle traction control only by braking force control. Thereby, a smooth vehicle start is realized.

Here, the stepwise transition (ST8) from the driving force distribution control to the braking force control can be performed in a plurality of steps or steplessly. For example, in this embodiment, the transition from the driving force distribution control to the braking force control is performed as follows. First, the command output values targetFx_low_μ and targetFx_high_μ to the drive wheels 11RR and 11RL when at least one of the condition (p) or the condition (q) is satisfied are set as targetFx ^* _low_μ and targetFx ^* _high_μ. Then, these command output values targetFx ^* _low_μ, targetFx ^* _high_μ and the following formulas (15) to (17) are used, the command output value targetFx_diff to the control differential 21, the command output value targetFx_eng to the engine 12, Further, a command output value targetFx_brake_low_μ to the wheel cylinder 32RR (32RL) of the drive wheel 11RR (11RL) on the road surface side having a low friction coefficient is calculated. In Expressions (14) to (16), B is a constant for determining the intervention speed of the braking force and is determined by adaptation.

targetFx_diff = MAX (targetFx ^* _high_μ−targetFx ^* _low_μ−BT, 0) (14)

targetFx_eng = MAX (targetFx ^* _high_μ + targetFx ^* _low_μ−BT, 2 ^* targetFx ^* _high_μ) (15)

targetFx_brake_low_μ = MAX (BT, targetFx ^* _high_μ−targetFx ^* _low_μ) (16)

  In such a configuration, the driving force distribution control is gradually stopped (relaxed) by using the command output value targetFx_diff to the control differential 21 according to Expression (14). Further, the engine output is gradually increased by using the command output value targetFx_eng to the engine 12 according to Expression (15). Further, the braking force control gradually intervenes by using the command output value targetFx_brake_low_μ to the wheel cylinder 32RR (32RL) according to Expression (16). Thereby, the smooth vehicle start by the driving force distribution control is realized, and the deterioration of the durability of the control differential 21 due to the difference between the left and right wheel speeds is suppressed.

  Next, when it is determined (ST7) that neither the condition (p) nor the condition (q) is satisfied, or stepwise transition (ST8) from driving force distribution control to braking force control is performed. When it is being performed, it is determined whether or not the slip of each of the drive wheels 11RR and 11RL is settled (ST9). In this determination step ST9, when the difference | VwRR−VwRL | between the wheel speeds VxRR and VxRL of the left and right drive wheels 11RR and 11RL is within a predetermined threshold (for example, 1.5 [m / s]) It is determined that the slip of the drive wheels 11RR and 11RL is settled. When the slip is not settled, the prediction determination steps ST6 and ST7 are performed again, and an immediate transition (ST3) from the driving force distribution control to the braking force control (ST3) or stepwise transition ( ST8) is performed. On the other hand, when the slip is settled, straddle traction control is terminated.

[effect]
As described above, in the vehicle motion control system 1, when the wheel speed difference between the left and right drive wheels 11RR and 11RL is equal to or less than a predetermined threshold value, the traction control (straddle traction) of the drive wheels 11RR and 11RL by the drive force distribution control is performed. (Hereinafter referred to simply as traction control). In such a configuration, the traction control is performed by the driving force distribution control in a situation where the wheel speed difference between the left and right driving wheels tends to be large, so that suitable vehicle motion control (for example, smooth start of the vehicle 10 on the crossing road) ) Is realized. Further, since the driving force distribution control is performed when the wheel speed difference between the left and right driving wheels 11RR and 11RL is equal to or less than a predetermined threshold value, the deterioration of the durability of the driving force distribution control device 2 due to the wheel speed difference is suppressed. There are advantages. For example, if the driving force distribution control (torque movement) is performed when the wheel speed difference exceeds a predetermined threshold (high differential), the durability of the driving force distribution control device may deteriorate.

  In the above configuration, when the wheel speed difference between the left and right drive wheels 11RR and 11RL is equal to or greater than a predetermined threshold, traction control by the drive force distribution control is prohibited. Thereby, there exists an advantage by which the deterioration of the durability of the driving force distribution control apparatus 2 resulting from the wheel speed difference of the driving wheels 11RR and 11RL is suppressed.

  Further, in the above configuration, the wheel speed difference between the left and right drive wheels 11RR and 11RL is based on the wheel speed ratio between the left and right drive wheels 11RR and 11RL and a predetermined numerical value relating to the durability of the drive force distribution control device 2. It is determined whether or not it is equal to or less than a predetermined threshold (ST4) (see FIG. 2). Accordingly, there is an advantage that it is appropriately determined whether or not the traction control by the driving force distribution control can be performed without deteriorating the durability of the driving force distribution control device 2.

  For example, in this embodiment, the wheel speeds VxRR and VxRL ratio VxRR / VxRL and the differential values ∇VxRR and ∇VxRL of the left and right drive wheels 11RR and 11RL are calculated, and these and a predetermined value related to the durability of the driving force distribution control device 2 The numerical values k1 and k2 are used to make the determination (ST4) (see FIG. 2 and equations (1) to (4)). And based on this determination result, either traction control (ST5) by driving force distribution control or traction control (ST3) by braking force distribution control is selected and executed. Specifically, when it is determined that the wheel speed difference between the left and right drive wheels 11RR and 11RL is within the design range of the drive force distribution control device 2 (below a predetermined threshold), the drive force distribution control is performed. Traction control (ST5) is selected. If it is determined that the wheel speed difference between the left and right driving wheels 11RR and 11RL is outside the design range of the driving force distribution control device 2 (exceeds a predetermined threshold), the traction control by the braking force distribution control is performed. (ST3) is selected. Thereby, the selection of the traction control (ST5) by the driving force distribution control or the traction control (ST3) by the braking force distribution control is appropriately performed according to the wheel speed difference between the left and right driving wheels 11RR and 11RL.

  Further, in this vehicle motion control system, when the traction control by the driving force distribution control is performed and the wheel speed difference between the left and right driving wheels 11RR and 11RL exceeds a predetermined threshold, the traction control by the driving force distribution control is prohibited. Then, the traction control by the braking force distribution control is switched (ST6) (see FIG. 2). Thereby, there is an advantage that the deterioration of the durability of the driving force distribution control device 2 due to the wheel speed difference between the driving wheels 11RR and 11RL is suppressed, and the slip of the driving wheels 11RR and 11RL is suppressed by the braking force distribution control. There are advantages to being.

  Further, in the above configuration, the wheel speed difference between the left and right drive wheels 11RR and 11RL is based on the wheel speed ratio between the left and right drive wheels 11RR and 11RL and a predetermined numerical value relating to the durability of the drive force distribution control device 2. It is determined whether or not a predetermined threshold is exceeded (ST6) (see FIG. 2). Accordingly, there is an advantage that it is appropriately determined whether or not the traction control by the driving force distribution control can be performed without deteriorating the durability of the driving force distribution control device 2.

  For example, in this embodiment, when the traction control (ST5) based on the driving force distribution control is performed, the prediction determination regarding the wheel speeds VxRR and VxRL of the left and right drive wheels 11RR and 11RL is performed in parallel (ST6) ( (See FIG. 2). In this prediction determination step ST6, (p) the ratio VxRR / VxRL of the wheel speeds VxRR and VxRL of the left and right drive wheels 11RR and 11RL and the differential values ∇VxRR and ∇VxRL are calculated, and these and the durability of the drive force distribution control device 2 are calculated. Determination is performed using predetermined numerical values k2 and k3 related to sex (see Expressions (10) to (13)). Based on the determination result, the traction control (ST5) by the driving force distribution control is continued, or the traction control (ST5) by the driving force distribution control is prohibited and the traction control (ST3) by the braking force distribution control is prohibited. ) Is selected. Specifically, when it is determined that the wheel speed difference between the left and right drive wheels 11RR and 11RL is within the design range of the drive force distribution control device 2 (below a predetermined threshold), the drive force distribution control is performed. Traction control (ST5) is continued as it is. On the other hand, if it is determined that the wheel speed difference between the left and right drive wheels 11RR and 11RL will eventually fall outside the design range of the drive force distribution control device 2 (exceeds a predetermined threshold), the traction control by the drive force distribution control ( ST5) is prohibited and switched to traction control (ST3) by braking force distribution control. As a result, even when the traction control (ST5) by the driving force distribution control is executed, appropriate control is performed so that the wheel speed difference between the left and right driving wheels 11RR and 11RL does not fall outside the design range of the driving force distribution control device 2. It has been broken.

  In the vehicle motion control system 1, traction control is performed by performing both driving force distribution control and braking force distribution control in parallel (ST8) (see FIG. 2). Accordingly, there is an advantage that the motion of the vehicle 10 can be more suitably controlled as compared with the configuration in which the traction control is performed by either the driving force distribution control or the braking force control.

  Further, in the vehicle motion control system 1, when it is predicted that the wheel speed difference between the left and right drive wheels 11RR and 11RL exceeds a predetermined threshold when the traction control by the driving force distribution control is performed, the current traction control is performed. Switching to traction control by both driving force distribution control and braking force distribution control (ST7 and ST8) (see FIG. 2). That is, when it is predicted that the wheel speed difference between the left and right drive wheels 11RR and 11RL exceeds a predetermined threshold when the traction control is performed only by the driving force distribution control, the braking force is changed from the traction control only by the driving force distribution control. A gradual transition to traction control by control is performed. In such a configuration, the traction control is more suitably performed as compared with the configuration in which the current traction control is directly switched to the traction control based only on the braking force control when the traction control based only on the driving force distribution control is performed. Thereby, there exists an advantage by which a smooth vehicle start is implement | achieved.

  For example, in this embodiment, when the traction control (ST5) based only on the driving force distribution control is performed, is (q) the difference in the estimated value of the friction coefficient of the road surface contacting the tires of the left and right driving wheels 11RR and 11RL large? And (r) whether or not the wheel speed difference between the left and right drive wheels 11RR and 11RL exceeds a predetermined threshold based on the determination result of whether or not the command output value targetFx_eng to the engine 12 is large (ST7). When either of these conditions is satisfied, a gradual transition from traction control based only on driving force distribution control to traction control based on braking force control is performed. Thereby, traction control is suitably performed.

  In this embodiment, the command output value targetFx_diff for the driving force distribution control device 2 gradually decreases and the command output for the braking force control device 3 is reduced by traction control by both the driving force distribution control and the braking force distribution control. The value targetFx_eng is set to gradually increase. At this time, the command output value targetFx_eng to the engine 12 (engine torque) is set to gradually increase. As a result, a gradual transition from traction control based only on driving force distribution control to traction control based on braking force control is successfully realized.

  Further, in this vehicle motion control system 1, when the traction control (ST8) by both the driving force distribution control and the braking force distribution control is performed, the wheel speed difference between the left and right driving wheels 11RR and 11RL exceeds a predetermined threshold value. In addition, the driving force distribution control is prohibited and the traction control is switched to only the braking force distribution control (ST6) (see FIG. 2). That is, even when the gradual transition from the traction control only by the driving force distribution control to the traction control by the braking force control is performed, the wheel speed difference between the left and right driving wheels 11RR and 11RL has a predetermined threshold value. If it exceeds, driving force distribution control is immediately prohibited. Thereby, there exists an advantage by which the deterioration of the durability of the driving force distribution control apparatus 2 resulting from the wheel speed difference of the driving wheels 11RR and 11RL is suppressed.

  As described above, the vehicle motion control system according to the present invention provides durability of the driving force distribution control when the traction control by the driving force distribution control is performed in a situation where the wheel speed difference between the left and right driving wheels tends to be large. It is useful in that it can suppress the deterioration of sex.

It is a block diagram which shows the vehicle motion control system concerning the Example of this invention. It is a flowchart which shows the effect | action of the vehicle motion control system described in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle motion control system 2 Driving force distribution control apparatus 21 Control differential 22RR, 22RL Drive shaft 3 Braking force control apparatus 31 Hydraulic circuit 32FR-32RL Wheel cylinder 33 Brake pedal 34 Master cylinder 4 Control system 42FR-42RL Wheel speed sensor 43 Steering angle Sensor 44 Yaw rate sensor 45 Longitudinal acceleration sensor 46 Lateral acceleration sensor 47 Vehicle speed sensor 48 Accelerator opening sensor 49 Brake pedal force sensor 10 Vehicle 11FR to 11RL Wheel 11RR, 11RL Drive wheel 12 Engine 14 Propeller shaft 15 Viscous coupling

Claims (10)

A driving force distribution control device capable of applying driving force to the left and right driving wheels and controlling the driving force distribution to the left and right driving wheels (hereinafter referred to as driving force distribution control), and the braking force of each driving wheel independently. A vehicle motion control system including a braking force control device capable of controlling (hereinafter referred to as braking force control) and performing traction control for suppressing slippage of the drive wheel,
A vehicle motion control system, wherein traction control by drive force distribution control is performed when a wheel speed difference between the left and right drive wheels is equal to or less than a predetermined threshold value.   The vehicle motion control system according to claim 1, wherein traction control by driving force distribution control is prohibited when a wheel speed difference between the left and right drive wheels exceeds a predetermined threshold.   Based on the wheel speed ratio between the left and right drive wheels and a predetermined numerical value regarding the durability of the driving force distribution control device, it is determined whether or not the wheel speed difference between the left and right drive wheels is equal to or less than a predetermined threshold. The vehicle motion control system according to claim 1 or 2.   When the wheel speed difference between the left and right driving wheels exceeds a predetermined threshold during the traction control by the driving force distribution control, the traction control by the driving force distribution control is prohibited and switched to the traction control by the braking force control. The vehicle motion control system according to any one of claims 1 to 3.   Based on the wheel speed ratio between the left and right drive wheels and a predetermined numerical value relating to the durability of the drive force distribution control device, it is determined whether or not the wheel speed difference between the left and right drive wheels exceeds a predetermined threshold. The vehicle motion control system according to claim 4.   The vehicle motion control system according to any one of claims 1 to 5, wherein the traction control is performed by performing both the driving force distribution control and the braking force distribution control in parallel.   When it is predicted that the wheel speed difference between the left and right drive wheels will exceed a predetermined threshold when the traction control is performed by the driving force distribution control, the traction control is performed by both the driving force distribution control and the braking force distribution control. The vehicle motion control system according to any one of claims 1 to 5, wherein the vehicle motion control system is switched to control.   Based on the determination result whether or not the difference between the estimated values of the friction coefficient of the road surface contacting the tires of the left and right drive wheels is large, or whether the command output value to the engine is larger than a predetermined threshold, The vehicle motion control system according to claim 7, wherein whether or not the wheel speed difference between the left and right drive wheels exceeds a predetermined threshold is predicted.   The command output value for the driving force distribution control device gradually decreases and the command output value for the braking force control device gradually increases in the traction control by both the driving force distribution control and the braking force distribution control. The vehicle motion control system according to claim 8.   When the traction control by both the driving force distribution control and the braking force distribution control is performed and the wheel speed difference between the left and right driving wheels exceeds a predetermined threshold, the driving force distribution control is prohibited and the braking force distribution control is performed. The vehicle motion control system according to any one of claims 7 to 9, wherein the vehicle motion control system is switched to traction control according to claim 7.

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