JP6387675B2 - Vehicle traction control device - Google Patents

Description

  The present invention relates to a traction control device for a vehicle that suppresses slippage of a drive wheel by performing braking traction control for controlling a braking force applied to the drive wheel.

  Conventionally, for example, an apparatus described in Patent Document 1 has been proposed as a traction control apparatus for this type of vehicle. In this traction control device, two slip state thresholds (a first slip state threshold and a second slip state threshold) having different sizes are prepared. Prior to the start of braking traction control, for example, the first slip state threshold is selected as the right drive wheel threshold, and the second slip state threshold is selected as the left drive wheel threshold. At the start of braking traction control, the braking force for the right drive wheel is adjusted according to the first slip state threshold, and the braking force for the left drive wheel is adjusted according to the second slip state threshold.

  In the above traction control device, the threshold value for the right driving wheel is changed from the first slip state threshold value to the second slip state threshold value during the execution of the braking traction control, and the threshold value for the left driving wheel is set to the second threshold value. The slip state threshold value is changed to the first slip state threshold value. Then, the braking force for the right driving wheel is adjusted according to the second slip state threshold, and the braking force for the left driving wheel is adjusted according to the first slip state threshold. In this way, the threshold value for the right driving wheel and the threshold value for the left driving wheel are alternately switched.

JP-A-8-72689

  By the way, when the braking traction control is performed, the driving force transmitted from the power source of the vehicle to the driving wheels is canceled by the braking force. Therefore, if there are many opportunities for execution of braking traction control, the energy efficiency of the vehicle will be reduced.

  An object of the present invention is to provide a traction control device for a vehicle that can increase the energy efficiency of the vehicle by reducing the opportunity to perform braking traction control.

  A vehicle traction control device for solving the above-described problem starts braking traction control that applies a braking force to a driving wheel when the slip amount of the driving wheel of the vehicle becomes equal to or greater than a braking control start threshold, A device that adjusts the slip amount of the wheel is assumed. And this apparatus is provided with the start threshold value determination part which determines the brake control start threshold value to the value according to the driving state of the vehicle.

  According to the above configuration, the braking control start threshold is variable according to the running state of the vehicle. Therefore, when it can be estimated that the necessity of the braking traction control is low based on the traveling state of the vehicle, the braking control start threshold value can be increased to make it difficult to start the braking traction control. And the energy efficiency of a vehicle can be raised now by reducing the implementation opportunity of braking traction control.

  In the vehicle traction control device, the start threshold value determination unit determines whether or not a condition for changing the braking control start threshold value is satisfied based on a running state of the vehicle, and the change is performed when the change condition is satisfied. The braking control start threshold value may be made larger than when the condition is not satisfied. In this case, the necessity for braking traction control is low, and when the change condition is satisfied, the necessity for braking traction control is high, and the braking control start threshold is made larger than when the change condition is not satisfied. Braking traction control is less likely to be performed.

  For example, when the driving wheel is slowly accelerating, the slip amount of the driving wheel, which is a difference obtained by subtracting the vehicle body speed from the wheel speed of the driving wheel, is difficult to increase. Therefore, it is possible to appropriately adjust the slip amount of the driving wheel by performing the driving traction control having lower responsiveness than the braking traction control and reducing the driving force transmitted from the power source of the vehicle to the driving wheel. Therefore, it can be estimated that the necessity of brake traction control is low. Therefore, the vehicle traction control device may include an acceleration calculation unit that calculates the wheel acceleration, which is the acceleration of the driving wheel, as the traveling state of the vehicle. In this case, it is preferable that the change condition includes that the wheel acceleration calculated by the acceleration calculation unit is less than the acceleration determination value.

  According to the above configuration, when the wheel acceleration of the drive wheel is less than the acceleration determination value, it can be estimated that the wheel acceleration is small. Therefore, when the change condition including that the wheel acceleration of the drive wheel is less than the acceleration determination value is satisfied, the braking control start threshold is set larger than when the change condition is not satisfied, and the braking traction control is started. It becomes difficult. Thus, by making it difficult to start the braking traction control only when it is estimated that the necessity of the braking traction control is low, the opportunity to perform the braking traction control can be appropriately reduced.

  In addition, when the road surface on which the vehicle travels is not a different left and right μ road where the μ value of the road surface on which the right driving wheel contacts and the μ value of the road surface on which the left driving wheel contacts the ground, the road surface is a different left and right μ road. Since the vehicle behavior is less likely to become unstable, it can be estimated that the necessity of braking traction control is low. Therefore, it is preferable that the change condition includes that the road surface on which the vehicle travels is not a different left and right μ road in which the μ value of the road surface on which the right driving wheel contacts the ground and the μ value of the road surface on which the left driving wheel contacts the ground.

  According to the above configuration, when the road surface is not the left and right different μ roads, the braking control start threshold is increased, so that it is difficult to start the braking traction control. Thus, it becomes difficult to start the braking traction control only when it is estimated that the necessity of the braking traction control is low, so that the opportunity to perform the braking traction control can be appropriately reduced.

  Further, when the driving force transmitted to the driving wheel is small, or when it is predicted that the driving force is difficult to increase, the slip amount of the driving wheel is difficult to increase. Therefore, it is possible to appropriately adjust the slip amount of the driving wheel by performing the driving traction control having lower responsiveness than the braking traction control and reducing the driving force transmitted from the power source of the vehicle to the driving wheel. Therefore, it can be estimated that the necessity of brake traction control is low. Therefore, the vehicle traction control device may include a correlation value calculation unit that calculates a driving force correlation value that correlates with the driving force transmitted from the power source of the vehicle to the driving wheels as the traveling state of the vehicle. In this case, it is preferable that the change condition includes that the driving force correlation value calculated by the correlation value calculation unit is less than the driving force correlation value determination value.

  According to the above configuration, when the driving force correlation value is less than the driving force correlation value determination value, it can be estimated that the driving force transmitted to the driving wheel is small or the driving force is hardly increased. Therefore, when the change condition including that the driving force correlation value is less than the driving force correlation value determination value is satisfied, the braking control start threshold is set larger than when the change condition is not satisfied, and the braking traction control is performed. It becomes difficult to start. Thus, it becomes difficult to start the braking traction control only when it is estimated that the necessity of the braking traction control is low, so that the opportunity to perform the braking traction control can be appropriately reduced.

  Here, when the braking traction control is performed, the braking force with respect to the driving wheel may be controlled so that the slip amount of the driving wheel approaches the target slip amount smaller than the braking control start threshold value. In this case, the vehicle traction control device preferably includes a target slip amount determination unit that increases the target slip amount as the braking control start threshold value increases.

  According to the above configuration, the target slip amount is changed according to the braking control start threshold value. Therefore, the difference between the braking control start threshold and the target slip amount is less likely to be larger than when the target slip amount is fixed to a predetermined value. For this reason, the braking force applied to the drive wheels due to the execution of the braking traction control is suppressed from being excessive. Therefore, during the execution of the braking traction control, the slip amount of the drive wheel can be appropriately adjusted by making the target slip amount variable according to the braking control start threshold value.

The schematic block diagram which shows a vehicle provided with the control apparatus which is one Embodiment of the traction control apparatus of a vehicle. The graph showing the driving | running | working area | region of the vehicle estimated that the necessity of braking traction control is low. The flowchart explaining the processing routine performed in order to determine the start timing of drive traction control and braking traction control. The flowchart explaining the process routine performed in order to determine a braking control start threshold value and target slip amount. FIG. 4 is a timing chart in a case where a change condition is satisfied during travel of the vehicle, where (a) shows the change in accelerator opening, (b) shows the change in wheel acceleration of the drive wheel, and (c) shows The transition of the slip amount of the drive wheel is shown. It is a timing chart when change conditions are not satisfied in the middle of running of vehicles, (a) shows change of accelerator opening, (b) shows change of wheel acceleration of a drive wheel, and (c). The transition of the slip amount of the drive wheel is shown.

Hereinafter, an embodiment of a vehicle traction control device will be described with reference to FIGS.
FIG. 1 illustrates an example of a vehicle including a control device 100 that is a traction control device for a vehicle according to the present embodiment. As shown in FIG. 1, the vehicle is a vehicle in which the rear wheels RL and RR function as drive wheels and the front wheels FL and FR function as driven wheels. Such a vehicle is provided with an engine 12 that is driven in accordance with an accelerator opening degree AC that is an operation amount of an accelerator pedal 11 by a driver. The driving force output from the engine 12 is transmitted to the rear wheels RL and RR through the automatic transmission 13 and the differential gear 14.

  The vehicle braking device 20 includes a hydraulic pressure generating device 22 to which a brake pedal 21 is drivingly connected, and a brake mechanism 30a, 30b, 30c, 30d provided for each wheel FL, FR, RL, RR. And a brake actuator 23 that adjusts the wheel cylinder pressure, which is the hydraulic pressure. Further, the brake device 20 is provided with a brake switch 210 that detects whether or not the brake pedal 21 is operated.

  The brake actuator 23 is configured to apply a braking force to each wheel FL, FR, RL, RR even when the driver is not operating the brake pedal 21. For example, the brake actuator 23 includes a differential pressure adjusting valve for generating a differential pressure between the brake hydraulic pressure in the master cylinder constituting the hydraulic pressure generating device 22 and the wheel cylinder pressure, and the brake fluid in the wheel cylinder. And an electric pump. The brake actuator 23 is provided with various valves for adjusting the wheel cylinder pressure for each of the wheels FL, FR, RL, and RR. That is, the brake actuator 23 can individually adjust the braking force for each wheel FL, FR, RL, RR.

  In addition to the brake switch 210, an accelerator opening sensor 220, a throttle opening sensor 230, and a wheel speed sensor 240 are electrically connected to the control device 100. The accelerator opening sensor 220 outputs a signal corresponding to the accelerator opening AC. The throttle opening sensor 230 outputs a signal corresponding to the opening SC of the electronic throttle provided in the intake passage of the engine 12. The wheel speed sensor 240 is provided for each individually corresponding wheel FL, FR, RL, RR, and outputs a signal corresponding to the wheel speed VW that correlates with the rotational speed of the corresponding wheel.

  The control device 100 includes an engine ECU 110 that controls the engine 12 and a brake ECU 120 that controls the brake actuator 23. Each of these ECUs 110 and 120 has a microcomputer constructed by a CPU, a ROM, a RAM, and the like. The control device 100 estimates the behavior of the vehicle based on information detected by a detection system such as various sensors and switches, and appropriately controls the engine 12, the brake actuator 23, and the like. Note that “ECU” means “Electronic Control Unit”.

  By the way, when the vehicle equipped with such a control device 100 is traveling, the drive traction control for adjusting the drive force applied to the drive wheels in the slip state, and the brake traction for adjusting the brake force for the drive wheels in the slip state. Control may be implemented. In order to suppress an increase in the fuel consumption of the vehicle and increase the energy efficiency of the vehicle, it is preferable to execute the drive traction control preferentially over the braking traction control.

  However, in the drive traction control, the output of the engine 12 is adjusted, so that the responsiveness is lower than that in the brake traction control. Therefore, when the slip amount Slp of the drive wheel is large and when the increase rate of the slip amount Slp is large, it is preferable to start the braking traction control early in order to ensure the stability of the vehicle behavior.

  Therefore, in the present embodiment, the braking control start threshold value SlpTh2 serving as a reference for starting the braking traction control is determined according to the wheel acceleration DVW obtained by time differentiation of the wheel speed VW of the driving wheel and the accelerator opening degree AC. That is, the driving force output from the engine 12 basically increases as the accelerator opening degree AC increases. Therefore, when the accelerator opening degree AC is less than the accelerator opening degree determination value ACTh, the driving force transmitted from the engine 12 to the driving wheel is difficult to increase, so that the slip amount Slp of the driving wheel is difficult to increase or the slip amount. It can be determined that the increase rate of Slp is small. Therefore, the control device 100 can use the accelerator opening degree AC as an example of a “driving force correlation value” that correlates with the driving force transmitted from the engine 12 to the driving wheels. In this case, the accelerator opening determination value ACTh corresponds to an example of a “driving force correlation value determination value”.

  Further, the increasing speed of the slip amount Slp of the drive wheel tends to increase as the wheel acceleration DVW increases. Therefore, when the wheel acceleration DVW is less than the acceleration determination value DVWTh, it can be determined that the slip amount Slp of the drive wheel is difficult to increase.

  Therefore, as shown in FIG. 2, when both the accelerator opening AC is less than the accelerator opening determination value ACTh and the wheel acceleration DVW is less than the acceleration determination value DVWTh, It can be estimated that the necessity of braking traction control is low. Therefore, the braking control start threshold SlpTh2 for determining the start timing of the braking traction control is increased. As a result, when it is estimated that the necessity of the braking traction control is low, the opportunity for performing the braking traction control can be reduced.

  However, when the vehicle is traveling on different left and right μ roads where the μ value of the road surface on which the left rear wheel RL is grounded and the μ value of the road surface on which the right rear wheel RR is grounded differ greatly, The behavior tends to be unstable. Therefore, in such a case, it is preferable not to increase the braking control start threshold SlpTh2 even when the above two conditions are satisfied.

That is, in the present embodiment, the braking control start threshold SlpTh2 is increased when a change condition including the following three conditions is satisfied. On the other hand, if at least one of the three conditions is not satisfied, it is determined that the change condition is not satisfied, and the braking control start threshold SlpTh2 is not increased.
(First condition) The accelerator opening AC is less than the accelerator opening determination value ACTh.
(Second condition) The wheel acceleration DVW is less than the acceleration determination value DVWTh.
(Third condition) The road surface on which the vehicle travels is not a different μ road.

  Next, a processing routine executed by the brake ECU 120 of the control device 100 in order to determine the start timing of the drive traction control and the brake traction control will be described with reference to FIG. This processing routine is a routine executed every preset control cycle.

  As shown in FIG. 3, in this processing routine, the brake ECU 120 subtracts the vehicle body speed VS from the wheel speed VW of the driving wheel, and sets the difference as the slip amount Slp of the driving wheel (step S11). The vehicle body speed VS is a value calculated based on at least one wheel speed of the wheel speeds VW of the wheels FL, FR, RR, RL, and the moving speed of the vehicle forward (or rearward) is determined by the wheel speed. It corresponds to the value converted into the rotation speed.

  Subsequently, the brake ECU 120 determines whether or not the calculated slip amount Slp of the drive wheel is equal to or greater than the drive control start threshold SlpTh1 (step S12). This drive control start threshold SlpTh1 is a reference for determining the start timing of drive traction control. If the slip amount Slp is equal to or greater than the drive control start threshold SlpTh1 (step S12: YES), the brake ECU 120 instructs the engine ECU 110 to start drive traction control (step S13), and then the process is performed to the next step. The process proceeds to S14. The engine ECU 110 that has received such an instruction starts drive traction control.

  On the other hand, when the slip amount Slp is less than the drive control start threshold value SlpTh1 (step S12: NO), the brake ECU 120 proceeds to the next step S14 without instructing the engine ECU 110 to start drive traction control. .

  In step S14, the brake ECU 120 determines whether or not the calculated slip amount Slp of the drive wheel is equal to or greater than the braking control start threshold value SlpTh2. If the slip amount Slp is greater than or equal to the braking control start threshold SlpTh2 (step S14: YES), the brake ECU 120 starts braking traction control (step S15). Thereafter, the brake ECU 120 once ends this processing routine. On the other hand, when the slip amount Slp is less than the braking control start threshold value SlpTh2 (step S14: NO), the brake ECU 120 ends this processing routine without performing the processing of step S15.

  In the brake traction control, the brake ECU 120 controls the brake actuator 23 so that the slip amount Slp of the drive wheel approaches the target slip amount SlpTr. At this time, the brake ECU 120 causes the slip amount Slp to approach the target slip amount SlpTr by feedback control. Therefore, immediately after the start of the braking traction control, the undershoot increases as the difference between the slip amount Slp at the start of the control and the target slip amount SlpTr, that is, the difference between the braking control start threshold SlpTh2 and the target slip amount SlpTr increases. Is likely to occur.

  Next, a processing routine executed by the brake ECU 120 to determine the braking control start threshold value SlpTh2 and the target slip amount SlpTr will be described with reference to FIG. This processing routine is a routine that is executed every predetermined control cycle when the braking traction control is not performed.

  As shown in FIG. 4, the brake ECU 120 calculates the accelerator opening AC based on the signal output from the accelerator opening sensor 220, and determines whether or not the accelerator opening AC is less than the accelerator opening determination value ACTh. Is determined (step S21). In other words, in the present embodiment, the brake ECU 120 also functions as a “correlation value calculation unit” that calculates the accelerator opening degree AC as the vehicle running state.

  If the accelerator opening degree AC is less than the accelerator opening degree determination value ACTh (step S21: YES), the brake ECU 120 calculates the wheel acceleration DVW of the drive wheel, and the wheel acceleration DVW is less than the acceleration determination value DVWTh. It is determined whether or not (step S22). In other words, in the present embodiment, the brake ECU 120 also functions as an “acceleration calculation unit” that calculates the wheel acceleration DVW of the drive wheels as the vehicle running state.

  When the wheel acceleration DVW is less than the acceleration determination value DVWTh (step S22: YES), the brake ECU 120 determines whether or not the road surface on which the vehicle is traveling is a different μ road on the left and right (step S23). For example, the brake ECU 120 determines that the road surface is a different μ road when the difference between the slip amount Slp of the right rear wheel RR that is the drive wheel and the slip amount Slp of the left rear wheel RL is greater than or equal to a determination value. be able to.

  If the road surface is not a different μ road (step S23: NO), the brake ECU 120 proceeds to step S25 described later. That is, when all of the first condition, the second condition, and the third condition are satisfied, that is, when the change condition is satisfied, the brake ECU 120 performs the process of step S25.

  On the other hand, if at least one of the determination result of step S21 is negative (NO), the determination result of step S22 is negative (NO), and the determination result of step S23 is positive (YES), the brake ECU 120 Shifts the processing to the next step S24. That is, when the change condition is not satisfied, the brake ECU 120 performs the process of step S24.

  In step S24, the brake ECU 120 sets the braking control start threshold value SlpTh2 to the normal first start threshold value SlpTh21, and sets the target slip amount SlpTr to the normal first target value SlpTr1. Thereafter, the brake ECU 120 once ends this processing routine.

  In step S25, the brake ECU 120 sets the braking control start threshold SlpTh2 to a second start threshold SlpTh22 that is larger than the first start threshold SlpTh21. Further, the brake ECU 120 sets the target slip amount SlpTr to a second target value SlpTr2 that is larger than the first target value SlpTr1. Thereafter, the brake ECU 120 once ends this processing routine. Therefore, in the present embodiment, the brake ECU 120 determines the braking control start threshold value SlpTh2 according to the traveling state of the vehicle such as the accelerator opening degree AC, the wheel acceleration DVW of the driving wheel, and whether the road surface is a different μ road. It also functions as a “start threshold value determination unit”. The brake ECU 120 also functions as a “target slip amount determination unit” that increases the target slip amount SlpTr as the braking control start threshold SlpTh2 increases.

Next, an effect | action at the time of a vehicle provided with the control apparatus 100 of this embodiment driving | running | working the road surface which is not different μ right and left will be described.
First, the case where the change condition is satisfied will be described with reference to the timing chart shown in FIG.

  As shown in FIGS. 5A, 5 </ b> B, and 5 </ b> C, when the driver starts operating the accelerator pedal 11 at the first timing t <b> 11 while the vehicle is stopped, the accelerator opening degree AC gradually increases. In this case, the accelerator opening AC is less than the accelerator opening determination value ACTh (step S21: Yes), the wheel acceleration DVW is less than the acceleration determination value DVWTh (step S22: Yes), and the road surface on which the vehicle travels. Are not different left and right μ roads (step S23: NO). Therefore, the braking control start threshold SlpTh2 is determined to be a second start threshold SlpTh22 that is larger than the first start threshold SlpTh21, and the target slip amount SlpTr is set to a second target value SlpTr2 that is larger than the first target value SlpTr1. It is determined (step S25).

  Therefore, the braking traction control is not started at the second timing t12 when the slip amount Slp of the drive wheel reaches the first start threshold value SlpTh21 (step S14: NO). In this case, the drive force transmitted to the drive wheels is reduced by the subsequent drive traction control, so that the slip amount Slp of the drive wheels is appropriately adjusted (step S13).

  If the road surface is a different μ road (step S22: NO), the accelerator opening AC is less than the accelerator opening determination value ACTh (step S21: Yes), and the wheel acceleration DVW is the acceleration determination value DVWTh. Even if both of them are satisfied (step S22: Yes), the change condition is not established. Therefore, the braking control start threshold SlpTh2 is determined as the first start threshold SlpTh21, and the target slip amount SlpTr is determined as the first target value SlpTr1 (step S25). Then, in this case, since the slip amount Slp of the drive wheel reaches the braking control start threshold value SlpTh2 (= SlpTh21) at the second timing t12 (step S14: Yes), the braking traction control is started (step S15).

Next, with reference to the timing chart shown in FIG. 6, a case where the change condition is not satisfied during the traveling of the vehicle will be described.
As shown in FIGS. 6A, 6 </ b> B, and 6 </ b> C, when the driver starts operating the accelerator pedal 11 at the first timing t <b> 21 while the vehicle is stopped, the accelerator opening degree AC gradually increases. In the initial stage of starting the vehicle, the accelerator opening AC is less than the accelerator opening determination value ACTh (step S21: Yes), the wheel acceleration DVW is less than the acceleration determination value DVWTh (step S22: Yes), In addition, all that the road surface on which the vehicle travels is not the left and right μ roads (step S23: NO) is established. Therefore, the braking control start threshold SlpTh2 is determined to be a second start threshold SlpTh22 that is larger than the first start threshold SlpTh21, and the target slip amount SlpTr is set to a second target value SlpTr2 that is larger than the first target value SlpTr1. It is determined (step S25). Therefore, the braking traction control is not started at the second timing t22 when the slip amount Slp of the drive wheel reaches the first start threshold value SlpTh21.

  Thereafter, the wheel acceleration DVW of the drive wheel increases as the accelerator opening degree AC increases. When the wheel acceleration DVW of the driving wheel reaches the acceleration determination value DVWTh at the third timing t23 (step S22: NO), the change condition is not satisfied. Therefore, the braking control start threshold value SlpTh2 is returned from the second start threshold value SlpTh22 to the first start threshold value SlpTh21, and the target slip amount SlpTr is returned from the second target value SlpTr2 to the first target value SlpTr1 (step). S24).

  In addition, before the wheel acceleration DVW of the drive wheel reaches the acceleration determination value DVWTh, the accelerator opening AC may be equal to or greater than the accelerator opening determination value ACTh (step S21: NO). Even in this case, the braking control start threshold SlpTh2 is returned from the second start threshold SlpTh22 to the first start threshold SlpTh21, and the target slip amount SlpTr is changed from the second target value SlpTr2 to the first target value SlpTr1. (Step S24).

  At the third timing t23 when the braking control start threshold value SlpTh2 is returned to the first starting threshold value SlpTh21 in this way, the slip amount Slp of the drive wheel is greater than or equal to the braking control start threshold value SlpTh2 (step S14: YES). Braking traction control is started (step S15). Then, the braking force on the driving wheel is controlled by executing the braking traction control, so that the slip amount Slp of the driving wheel is adjusted to approach the target slip amount SlpTr (= first target value SlpTr1).

As mentioned above, according to the said structure and effect | action, the effect shown below can be acquired.
(1) The braking control start threshold value SlpTh2 is varied according to the traveling state of the vehicle. Therefore, when it can be estimated that the necessity of the braking traction control is low based on the traveling state of the vehicle, the braking control start threshold SlpTh2 can be increased to make it difficult to start the braking traction control. As a result, the opportunity for executing the braking traction control is reduced, and the energy efficiency of the vehicle can be increased.

  (2) In the present embodiment, when all of the above three conditions are satisfied, it can be estimated that the necessity of braking traction control is low. Therefore, the braking control start threshold SlpTh2 is larger than the first start threshold SlpTh21. A start threshold value SlpTh22 of 2 is determined. Therefore, when it is estimated that the necessity of the braking traction control is low, the opportunity for performing the braking traction control can be appropriately reduced.

  (3) On the other hand, when at least one of the above three conditions is not satisfied, it can be estimated that the necessity of the braking traction control is high. Therefore, the braking control start threshold value SlpTh2 is determined as the first starting threshold value SlpTh21. The Thereby, when it can be estimated that the necessity of the braking traction control is high, the braking traction control can be started early as in the conventional case. Therefore, the braking traction control can be appropriately performed when the braking traction control is required while reducing the fuel consumption of the vehicle.

  (4) In the present embodiment, the target slip amount SlpTr is changed according to the braking control start threshold SlpTh2. Therefore, the difference between the braking control start threshold SlpTh2 and the target slip amount SlpTr is less likely to be larger than when the target slip amount SlpTr is fixed to a predetermined value. For this reason, the braking force applied to the drive wheels due to the execution of the braking traction control is suppressed from being excessive. Therefore, during the braking traction control, the slip amount Slp of the driving wheel can be adjusted appropriately.

The above embodiment may be changed to another embodiment as described below.
As long as the target slip amount SlpTr can be varied according to the braking control start threshold value SlpTh2, the target slip amount SlpTr may be changed by another method different from the above method. For example, a value obtained by subtracting a specified value from the braking control start threshold SlpTh2 may be set as the target slip amount SlpTr. Even in this case, the target slip amount SlpTr can be increased when the braking control start threshold SlpTh2 is large, and can be decreased when the braking control start threshold SlpTh2 is small. Therefore, an effect equivalent to the effect (4) can be obtained.

  The braking control start threshold SlpTh2 may be gradually changed in accordance with the change in the accelerator opening degree AC or the change in the wheel acceleration DVW of the driving wheel. For example, the reference threshold value is “X”, the first correction value that is increased as the accelerator opening AC is smaller is “α”, and the second correction value that is increased as the wheel acceleration DVW of the drive wheel is smaller is “ When “β” is set, the braking control start threshold value SlpTh2 may be the sum of the reference threshold value X, the first correction value α, and the second correction value β. Even in this case, the braking control start threshold SlpTh2 can be set to a value according to the traveling state of the vehicle. As a result, the same effect as the effect (1) can be obtained.

  When at least one of the three conditions is satisfied, it may be determined that the change condition is satisfied, and the braking control start threshold SlpTh2 and the target slip amount SlpTr may be increased. Even in this case, the same effect as the effect (1) can be obtained.

  If the change condition includes that the accelerator opening degree AC is less than the accelerator opening degree determination value ACTh, the wheel acceleration DVW is less than the acceleration determination value DVWTh, and the road surface on which the vehicle travels is different μ It may not include that it is not a road.

  If the change condition includes that the wheel acceleration DVW is less than the acceleration determination value DVWTh, the accelerator opening degree AC is less than the accelerator opening determination value ACTh, and the road surface on which the vehicle travels is different from right to left μ. It may not include that it is not a road.

  If the change condition includes that the road surface on which the vehicle is traveling is not a different μ road, the wheel acceleration DVW is less than the acceleration determination value DVWTh, and the accelerator opening AC is the accelerator opening determination value ACTh It is not necessary to include that it is less than.

  In the above embodiment, the accelerator opening degree AC is used as the driving force correlation value that correlates with the driving force transmitted from the power source of the vehicle to the driving wheel. For example, a value other than the accelerator opening degree AC may be adopted. For example, as the driving force correlation value, an opening degree SC of an electronic throttle provided in the intake passage of the engine 12 can be cited. In this case, it is determined whether or not the opening degree SC of the electronic throttle is less than the opening degree determination value corresponding to the “driving force correlation value determination value”. By using the opening degree SC of the electronic throttle in this way, even when the vehicle travels without the accelerator pedal 11 (so-called automatic travel of the vehicle), the opportunity for performing the braking traction control is appropriately set. It can be reduced.

  The vehicle provided with the control device 100 may be a front wheel drive vehicle in which the front wheels FL and FR function as drive wheels and the rear wheels RL and RR function as driven wheels, or all the wheels FL, FR and RL. , RR may be a four-wheel drive vehicle that functions as drive wheels.

  -As a vehicle provided with the said control apparatus 100, the electric vehicle provided with a motor as a motive power source may be sufficient, and the hybrid vehicle provided with both an engine and a motor as a motive power source may be sufficient.

  DESCRIPTION OF SYMBOLS 12 ... Engine which is an example of motive power source, 100 ... Control apparatus which is an example of traction control apparatus of vehicle, 120 ... Brake which is an example of a start threshold value determination part, an acceleration calculating part, a correlation value calculating part, and a target slip amount calculating part ECU, FL, FR: front wheel as an example of driving wheel, RL, RR: rear wheel as an example of driving wheel, AC: accelerator opening as an example of driving force correlation value, ACTh: driving force correlation value determination value Accelerator opening determination value as an example, DVW ... wheel acceleration, DVWTh ... acceleration determination value, SC ... electronic throttle opening as an example of driving force correlation value, Slp ... slip amount, SlpTh2 ... braking control start threshold, SlpTr ... Target slip amount.

Claims (4)

In the traction control device for a vehicle that starts braking traction control for applying a braking force to the driving wheel when the slip amount of the driving wheel of the vehicle is equal to or greater than a braking control start threshold, and adjusts the slip amount of the driving wheel.
A start threshold value determining unit for determining the brake control start threshold value to a value according to the running state of the vehicle ;
An acceleration calculation unit that calculates wheel acceleration that is the acceleration of the driving wheel as a running state of the vehicle,
The start threshold value determining unit determines whether or not a condition for changing the braking control start threshold value is satisfied based on a running state of the vehicle, and the change condition is not satisfied when the change condition is satisfied. The brake control start threshold is set larger than when
The change condition includes a vehicle traction control device characterized in that the wheel acceleration calculated by the acceleration calculation unit is less than an acceleration determination value . In the traction control device for a vehicle that starts braking traction control for applying a braking force to the driving wheel when the slip amount of the driving wheel of the vehicle is equal to or greater than a braking control start threshold, and adjusts the slip amount of the driving wheel.
A start threshold value determining unit for determining the braking control start threshold value to a value according to the running state of the vehicle ;
The start threshold value determining unit determines whether or not a condition for changing the braking control start threshold value is satisfied based on a running state of the vehicle, and the change condition is not satisfied when the change condition is satisfied. The brake control start threshold is set larger than when
The change condition includes that the road surface on which the vehicle travels is not a different left and right μ road in which the μ value of the road surface on which the right driving wheel contacts and the μ value of the road surface on which the left driving wheel contacts the ground are different. Vehicle traction control device. As the running condition of the vehicles, comprising a correlation value calculation unit for calculating a driving force correlation value that is correlated with driving force transmitted to the drive wheels from the power source of the vehicle,
The change condition of the vehicle traction control system according to claim 1 or claim 2 comprising the driving force correlation value calculated by the correlation value calculation section is less than the driving force correlation value determination value. When performing the braking traction control, the braking force for the driving wheel is controlled so that the slip amount of the driving wheel approaches the target slip amount that is smaller than the braking control start threshold.
The traction control device for a vehicle according to any one of claims 1 to 3 , further comprising a target slip amount determination unit that increases the target slip amount as the braking control start threshold value increases.