JPH0550912A - Slip control device for vehicle - Google Patents

Abstract

PURPOSE:To provide accurate judgment for a road by braking when a difference in slip quantities of right and left driving wheels becomes above a fixed quantity, and judging the road to be the split road when a difference in the lock tendency of right and left driven wheels is large, and the driving and the driven wheel having larger slip quantity are positioned on the same side. CONSTITUTION:Signals given by a wheel speed sensors S1-S4, an acceleration switch S5, and brake switches S6, S7 are inputted into a control means 51, which controls an engine output regulating means 9, hydraulic regulating valves 15L-15R and a cut-off poppet valve 38. In this case, the engine output regulating means 9 changes over each control pattern fitted to running on an ordinary road or the split road on the output of a control pattern changing means 52 to receive a signal issued from a split road judging means 53 for controlling the car. The split road judging means 53 brakes the car when a difference in the slip quantity of right and left driving wheels becomes above a fixed value, and judges the road to be the split road when a difference in the lock tendency of right and left driven wheels is large, and the driving and the driven wheel having the larger slip quantity are positioned on the same side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle slip control device.

[0002]

2. Description of the Related Art A slip control device (traction control device) for a vehicle is designed to prevent the drive wheel from slipping due to excessive driving torque and declining the acceleration performance when the vehicle accelerates. Is detected, and the engine output and the braking force of the driving wheels are controlled so that the slip amount of the driving wheels becomes a target value (the engine output is reduced,
It is generally known to increase the braking force).

By the way, when the road surface on which a vehicle is traveling is viewed, the friction coefficient of the road surface is not constant over the entire surface,
A so-called split road may be a so-called split road in which one of the left and right wheels has a high friction coefficient on one side road surface portion and the other wheel has a low friction coefficient on the opposite side road surface portion.

In contrast to such a split road, in the technical field of the anti-skid brake system, when the difference between the braking forces applied to the left and right wheels exceeds a predetermined value, the split road is determined and the split road is judged. There is a proposal to carry out control suitable for running (Japanese Patent Publication No. 57-
53218). That is, this proposal limits the increase in the higher braking force when the difference between the braking forces applied to the left and right wheels exceeds a predetermined value.

[0005]

On the split road as described above, the control mode different from the normal road (the normal road in which the friction coefficients of the rolling road surface portions of the left and right wheels are substantially equal) is adopted. Also in the field of the slip control device, it is desirable to adopt it from the viewpoint of improving the running stability and acceleration of the vehicle. However, in such a change of the control mode, it is necessary to be able to accurately determine whether or not the road is a split road, and if not, the change of the control mode will cause a decrease in acceleration. easy.

That is, an object of the present invention is to make it possible to change the control mode after easily and accurately determining whether the road is a split road or not.

[0007]

In order to solve the above problems, the present invention applies a braking force to the driven wheels during slip control, and determines whether or not the road is a split road based on the magnitude of the locking tendency. Is to do.

That is, the first means for solving the above-mentioned problems is to apply a driving force to each of the two drive wheels so that the drive force is applied to the both drive wheels so that the slip amount of the left and right drive wheels with respect to the road surface becomes a target value. A control mode suitable for running on a normal road in which the friction coefficients of rolling road surfaces are substantially equal to each other, and a control mode suitable for running on a split road in which the friction coefficients of the rolling road surfaces of the two drive wheels are different from each other. A slip control device for a vehicle, comprising a control means that can be switched between and controlled, wherein a braking force is applied to the left and right driven wheels during operation of the control means, and a difference in locking tendency between the left and right driven wheels is generated. When the value is large, the split road determination means determines that the vehicle is traveling on the split road, and when the split road determination means determines that the vehicle is traveling on the split road, the control mode of the control means is split. And it is characterized in that a control mode changing means for changing the manner suitable for the accomplishment of bets path.

A second means for solving the above-mentioned problem is that the split road determination means is operated when the control means is in operation and the slip amount difference between the left and right driving wheels is equal to or more than a predetermined value. A braking force is applied to the driven wheels, and the difference between the left and right driven wheels has a large difference in locking tendency and the drive wheel with the larger slip amount and the driven wheel with the larger locking tendency are located on the same side of the left and right sides. Sometimes, the judgment is made while traveling on a split road.

A third means for solving the above problem is that the control means controls the engine output so as to reduce the engine output so that the slip amount of the drive wheels with respect to the road surface becomes a target value, and the drive wheel with respect to the road surface. A brake control system that controls the braking force applied to the drive wheels so that the slip amount reaches a target value, and the control mode changing means determines that the engine control system is operating when the vehicle is traveling on a split road. The target value of is set higher than that when traveling on a normal road.

[0011]

In the first means, when the braking force is applied to the left and right driven wheels during the operation of the control means, the large difference in the locking tendency between the left and right driven wheels means that the locking tendency is larger. It means that the driven wheel rolls on a road surface having a low friction coefficient (hereinafter referred to as “μ”), and the driven wheel having a small locking tendency is rolling on a high μ road surface. That is, by observing the difference in the magnitude of the lock tendency,
It is possible to determine whether or not the road surface on which the vehicle is traveling is a split road. Then, when it is determined that the vehicle is traveling on the split road, the control mode of the control unit is changed by the control mode changing unit, which facilitates running on the split road.

In the second means, the split road judging means applies a braking force to the left and right driven wheels when the difference between the slip amounts of the left and right driving wheels is a predetermined value or more, and the slip amount of the left and right driving wheels is increased. Since it is determined whether or not the road is a split road in consideration of the difference, the content of the determination becomes more accurate.

That is, when the difference between the slip amounts of the left and right drive wheels is equal to or greater than the predetermined value, it can be considered that the drive wheel with the larger slip amount is rolling on the low μ road surface. When the drive wheel with the larger slip amount and the driven wheel with the larger locking tendency are located on the same side of the left and right, both the front wheels and the rear wheels roll on the low μ road surface, This means that both the front wheels and the rear wheels located on the opposite side are rolling on the high μ road surface, and there is a high possibility that the road is a split road. In other words, in the case of the first means,
Even if it is not actually a split road, the split road is determined even when one of the left and right driven wheels temporarily rolls on the low μ road surface. Since both the driven wheels are viewed, it is possible to prevent the erroneous determination that the vehicle is traveling on the split road due to the temporary rolling of the low μ road surface.

In the case of performing engine control and brake control for adjusting the slip amount of the drive wheels, the engine output reduction control is performed based on the slip of the drive wheels on the low μ road surface side during traveling on a split road. At the same time, the braking force is applied to the drive wheels on the low μ road surface side. As a result, the drive wheels on the low μ road surface side are prevented from slipping, but the drive wheels on the high μ road surface side do not originally require engine control and brake control. On the other hand, in the third means, the target value for engine control is set to a higher value when traveling on a split road than when traveling on a normal road, and the reduction in engine output is restricted. Therefore, although the slip amount of the drive wheels on the low μ road surface side is mainly adjusted by the brake control, the engine output itself can be increased by reflecting the driver's intention. That is, while suppressing the slip of the drive wheels on the low μ road surface side by the brake control, a high engine output can be given to the drive wheels on the high μ road surface side, which is unlikely to cause the slip, so that the acceleration of the vehicle can be obtained. In other words, if the target value for engine control is the same when traveling on a slip road and when traveling on a normal road, an increase in engine output is restricted by the slip of the drive wheels on the low μ road surface side. However, in the case of the above-mentioned third means, the drive wheels on the high μ road surface side are effectively used for accelerating the vehicle by changing the target value of the engine control. Is what you can do.

[0015]

Therefore, according to the first means, the braking force is applied to the left and right driven wheels during the operation of the control means, and when the difference in the locking tendency between the left and right driven wheels is large, the vehicle is on the split road. And a split road determination means for determining that the vehicle is traveling, and a control mode for changing the control mode of the control means to a mode suitable for running on a split road when the split road determination means determines that the split road is traveling. Since the change means is provided, it is possible to easily and accurately determine whether or not the vehicle is on the split road with a relatively high probability, and to easily drive the vehicle on the split road.

According to the second means, the split road judging means brakes the left and right driven wheels when the control means is in operation and the slip amount difference between the left and right driving wheels is a predetermined value or more. When a force is applied and the difference between the left and right driven wheels in the locking tendency is large and the slip amount is larger and the driven wheel in the larger locking tendency is located on the same side of the left and right sides, the split Since it is determined that the vehicle is traveling on a road, it can be more accurately determined whether or not the vehicle is on a split road.

According to the third means, in the engine control and the brake control for adjusting the slip amount of the drive wheels, the target value of the engine control is made higher during the split road traveling than during the normal road traveling. The engine output is regulated by setting the low μ, so it is possible to suppress slipping of the drive wheels on the low μ road surface side while suppressing high slippage.
It is possible to enhance the acceleration of the vehicle by using the drive wheels on the road surface side.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, 1FL is a left front wheel, 1FR is a right front wheel, 1RL is a left rear wheel, and 1RR is a right rear wheel. The engine 2 is mounted horizontally on the front part of the vehicle body, and the torque generated by the engine 2 is transmitted to the clutch 3, the transmission 4, and the differential gear 5, and then the left front wheel 1FL is passed through the left drive shaft 6L. To the right front wheel 1FR via the right drive shaft 6R. In this way, the vehicle has front wheels 1F.
L and 1FR are the driving wheels, and the rear wheels 1RL and 1RR are the driven wheels, which are the driven wheels.

Brake 7FL to 7R mounted on each wheel
R is a hydraulic disc brake.
In addition, the master cylinder 8 as a brake fluid pressure generation source
Is a tandem type having two discharge ports 8a and 8b. The brake pipe 13 extending from one discharge port 8a of the master cylinder 8 is branched into two in the middle,
The branch pipe 13F is connected to the left front wheel brake 7FL (the wheel cylinder mounted inside the caliper), and the branch pipe 13R is connected to the right rear wheel brake 7RR.
The branch pipe 14 extending from the other discharge port 8b of the master cylinder 8 is also branched into two, the branch pipe 14F is connected to the right front wheel brake 7FR, and the branch pipe 14R is connected to the left rear wheel brake 7RL. ..

Branch pipe 13 for front wheels, that is, for drive wheels
Electromagnetic hydraulic pressure adjusting valves 15L and 15R are connected to F and 14F for brake control of driving wheels. The hydraulic pressure adjusting valves 15L, 15R supply the brake hydraulic pressure from the master cylinder 8 to the brakes 7FL, 7FR and release the brake hydraulic pressure of the brakes 7FL, 7FR to the reservoir tanks 22L, 22R via the pipes 21L, 21R. The mode to be performed is switched. The brake fluid in the reservoir tank 21L is piped to the check valve 24L by the pump 23L.
The brake fluid in the reservoir tank 22R is returned to the pipe 14 via the pipe 25R to which the check valve 24R is connected, by the pump 23R.

Branch pipe 13 for rear wheels, that is, for driven wheels
Electromagnetic hydraulic pressure adjusting valves 16L and 16R, which are similar to those on the drive wheel side, are connected to R and 14R for split road determination. The hydraulic pressure adjusting valves 16L and 16R are used to release brake hydraulic pressure. A pipe having a reservoir tank, a pump and the like similar to the drive wheel side is connected (not shown).

The stepping force on the brake pedal 12 is
It is transmitted to the master cylinder 8 via a booster or brake booster 11. This booster 11 is basically the same as a known vacuum booster, but during slip control, as will be described later, it performs a boosting action even if the brake pedal is not depressed. Is configured.

The booster 11 has a case 31 fixed to the vehicle body and the master cylinder 8, and the inside of the case 31 is
Diaphragm 32 and valve body 33 fixed to this
Define a first chamber 34 and a second chamber 35. Negative pressure (for example, intake negative pressure of the engine 2) is constantly supplied to the first chamber 34, and when the brake pedal is not depressed, the second chamber 35 communicates with the first chamber 34 and the booster 11 Is deactivated. When the brake pedal 12 is depressed, the atmospheric pressure is supplied to the second chamber 35, which causes the diaphragm 32 to move.
Is displaced forward together with the valve body 33 to perform a boosting function.

The switching between the negative pressure supply and the atmospheric pressure supply to the second chamber 35 is basically performed by a valve device mounted inside the valve body 33. This valve body 33
The part will be described with reference to FIG.

First, the valve body 33 has a power piston 41 fixed to the diaphragm 32, and a reaction disc 42 and a base end portion of the output shaft 43 are provided in a recess 41a formed in the power piston 41. It is fitted. The output shaft 43 serves as an input shaft of the master cylinder 8. Further, a valve plunger 45 is attached inside the valve body 33 at the tip of the input shaft 44 connected to the brake pedal 12. A vacuum valve 46 is disposed behind the valve plunger 45.

The power piston 41 has a pressure introducing passage 50.
The pressure introducing passage 50 is always communicated with the space X formed around the valve plunger 45. This space X is always in communication with the second chamber 35. A valve seat 47 on which the vacuum valve 46 is seated is formed at the opening end of the pressure introducing passage 50 toward the space X. Further, the vacuum valve 46 is a valve plunger 45.
The valve seat 45a formed at the rear end is also seated on and off.

In the above structure, it is assumed that a negative pressure is being introduced into the pressure introducing passage 50. In this state, if the brake pedal 12 is not operated, the vacuum valve 46 is seated on the valve seat 45a by the urging force of the springs 48 and 49 in the state of FIG.
It is separated from 7. Therefore, the pressure introducing passage 50
Negative pressure from is introduced into the second chamber 35 through the space X,
There is no boosting effect.

When the brake pedal 12 is depressed,
The input shaft 44 and hence the valve plunger 45 are moved forward (moved leftward in the drawing). During this forward movement, the vacuum valve 46
Is first seated on the valve seat 47, and the space X and the pressure introducing passage 50 are
Communication with the vacuum valve 46 and then the valve seat 45
a is separated. By separating the vacuum valve 46 and the valve seat 45a, the atmospheric pressure from the rear of the valve body 33 is introduced into the space X, and the second chamber 35 becomes the atmospheric pressure. As a result, the diaphragm 32 is displaced forward together with the valve body 33, and as a result, the output shaft 43 moves forward and a boosting action is performed. The brake reaction force from the master cylinder 8 is transmitted to the valve plunger 45 and thus the brake pedal 12 via the reaction disc 42.
When the depression operation force of the brake pedal 12 is released, the return spring 36 (see FIG. 1) returns to the state of FIG. 2 to prepare for the next boosting action.

The part described above is the same as that of the known vacuum booster, but in this embodiment, for the slip control and the split path determination, the negative pressure of the first chamber 34 is set to the pressure introducing passage 50. The state where pressure is introduced and the state where atmospheric pressure is introduced are switched. That is, the first chamber 3
4 and the pressure introducing passage 50 are connected via a pipe 37,
A three-way electromagnetic switching valve 38 (see FIG. 1) is connected to the pipe 37. This switching valve 38 is provided in the pressure introducing passage 5 during demagnetization.
0 is communicated with the first chamber 34, and the pressure introducing passage 50
Introduce atmospheric pressure to. When the switching valve 38 is excited and the atmospheric pressure is introduced into the pressure introducing passage 50, the space X and therefore the second chamber 35 becomes the atmospheric pressure even if the brake pedal 12 is not depressed, and as a result, A brake fluid pressure is generated in the master cylinder 8 by a boosting action.

<Control System> Next, the control system will be described.
The control system is configured by using a microcomputer, and in FIG. 1, 51 is a control means for performing engine control and brake control. The control means 51 includes:
The signals from the sensors or switches S1 to S7 and the signal from the control mode changing means 52 are input. A signal from the split road judging means 53 is inputted to the control mode changing means 52.

The sensors S1 to S4 are connected to the wheels 1FL to 1FL, respectively.
The rotation speed of 1RR is detected. Switch S5
Is an accelerator switch that is turned on when the accelerator pedal 10 is fully closed. The switches S6 and S7 are operated when the brake pedal 12 is depressed, and for example, one switch is a normally open type switch,
The other is a normally closed type. Further, from the control means 51, an engine output adjusting means 9 for engine control, a hydraulic pressure adjusting valve 15 for brake control or split road determination.
Control signals are output to the L, 15R, 16L, 16R and the switching valve 38. The engine output adjusting means 9 adjusts the generated torque by combining the number of fuel cut cylinders and the ignition timing adjustment.

The control means 51 will be described in detail. The control means 51 is a slip determination threshold value setting means, a road surface μ detecting means, a slip amount detecting means, a slip determining means, a control target value setting means, a control amount calculating means, Also, output means for controlling the engine output and the brake are provided, and based on the output from the control mode changing means 52, μ of the rolling road surface portion of each of the left and right drive wheels 1FL, 1FR is substantially. Both drive wheels 1FL are switched by switching between a control mode suitable for running on the same normal road and a control mode suitable for running on a split road in which μ of rolling road surface portions of the both drive wheels 1FL, 1FR are different from each other. , 1FR to control the driving force applied.

[Setting of Slip Determination Threshold, Detection of Road Surface μ] This slip determination threshold is for determining whether or not slip control is required, and there are a control start threshold and a control continuation threshold. .. These thresholds (unit: km / h)
Is calculated based on the vehicle body acceleration VG and the road surface μ.

To calculate the vehicle body acceleration VG, a timer A (1
00 msec count) and timer B (500 msec count). That is, the vehicle body acceleration VG is a vehicle body speed Vr of 100 msec for every 100 msec (in the case of this example, the two wheel speeds of the driven wheels 1RL and 1RR) until 500 msec has elapsed (the vehicle body acceleration is not sufficiently large) from the start of slip control. Based on the change of the faster wheel speed, unit; km / h), it is calculated by the following equation (1), and after 500 msec has elapsed (vehicle body acceleration has sufficiently developed), the change in vehicle body speed Vr for 500 msec every 100 msec. It is calculated by the following equation (2).

-(1) Expression-VG = Gk1 * {Vr (k) -Vr (k-100)}-(2) Expression-VG = Gk2 * {Vr (k) -Vr (k-500)} Above Gk1 and Gk2 are coefficients. Also, Vr (k) is present, Vr (k-100) is 100 msec ago, and Vr (k-500) is 50
Each vehicle speed is 0 msec before.

Then, from the vehicle body acceleration VG and the vehicle body speed Vr calculated as described above, the road surface μ is obtained by three-dimensional interpolation according to the following Table 1. The road surface μ is set to 3.0 when the slip control is not being performed.

[0037]

[Table 1]

The control start threshold value is shown in Table 2 below.
The control continuation threshold value is calculated by three-dimensional interpolation according to Table 3 below.

[0039]

[Table 2]

[0040]

[Table 3]

In this case, the engine control is started immediately after the slip amount, which will be described later, exceeds the control start threshold value, but the brake control is started with a predetermined delay time. The control is terminated when the slip amount is below the control continuation threshold value for 1000 msec.

[Slip amount calculation] Left and right drive wheels 1FL, 1
The vehicle body speed Vr is subtracted from the FR wheel speeds VFL and VFR to obtain the slip amounts SL and SR of the two wheels, and the average slip amount SAv is calculated based on the slip amounts SL and SR. The higher slip amount of the slip amounts SL and SR is determined as the maximum slip amount SHi. SHi is used in engine control, and SL and SR are used to independently control the braking force applied to the left and right drive wheels in brake control.

[Setting of control target value] This control target value (unit: km / h) is a target value as the slip amount of the drive wheels 1FL and 1FR, and the engine control target value SET
Is calculated based on the vehicle speed Vr and the road surface friction coefficient μ by three-dimensionally interpolating according to Table 4 below.

[0044]

[Table 4]

The brake control target value SBT is also the same as the engine control target value SET and the vehicle speed Vr and the road surface μ
Based on and, the calculation is set. In this case, SBT> SET is set on the assumption that the vehicle is traveling on a normal road, but SET is changed to a higher setting when traveling on a slip road, as will be described later.

[Control amount calculation] The engine control amount is calculated based on the deviation EN of the average slip amount SAv from the control target value SET and the time change rate DEN of this deviation. However, at the start of control, an initial correction for forcibly increasing the control amount is added to achieve early convergence of slip.

Similarly to the engine control amount, the brake control amount is also the deviation of the slip amounts SL and SR from the control target value,
It is calculated based on the change rate of this deviation.

[Output control] Regarding the ignition timing, the retard amount is determined according to the engine control amount,
Will be output. The fuel injection is limited by controlling the number of cylinders to be used based on the engine control amount. The brake is performed by outputting a control signal according to the brake control amount (duty control).

<Split Road Judgment and Control Mode Change> First, the split road judgment means 53 will be described. The split road determination means 53 is operated when the control means 51 is in operation (during slip control, preferably brake control) and when the condition that the slip amount difference between the left and right driving wheels is a predetermined value or more is satisfied, It is determined whether or not the road is a split road. The slip amount difference between the left and right driving wheels is calculated by the slip amount calculating means, and the slip amount S between the left and right driving wheels is calculated.
It is calculated based on L and SR. The calculation of this slip amount difference requires whether or not only one driving wheel causes a large slip (it can be determined that only one driving wheel is rolling on a low μ road surface), that is, a split road judgment is required. This is for determining whether or not the state.

Thus, when the above condition is satisfied, the split road determination means 53 causes the driven wheel branch pipe 13R,
The hydraulic pressure control valves 16L and 16R of 14R are opened, a braking force is applied to the left and right driven wheels, and the difference in locking tendency between the left and right driven wheels is compared. This locking tendency is determined based on the magnitude of the deceleration of each driven wheel due to the application of the braking force, and when the difference between the deceleration of the left and right driven wheels is greater than or equal to a predetermined value, the locking tendency Judge that the difference is large. Then, when the driving wheel with the larger slip amount and the driven wheel with the larger locking tendency are located on the same side of the left and right sides, it is determined that the vehicle is traveling on the split road.

When the split road judging means 53 judges that the vehicle is traveling on the split road, the control mode changing means 52 corrects the engine control target value SET so as to increase by a predetermined amount while keeping the brake control target value SBT as it is. .. As a result, the control mode of the control means 51 is changed to the slip control centering on the brake control.

The control flow for the split road determination and control mode change is shown in FIG. That is, when the slip control is being performed and the absolute value | SL-SR | of the slip amount difference between the left and right driving wheels is equal to or larger than the predetermined value So, the braking force is applied to the left and right driven wheels (steps S1 to S1). S
3). The absolute value | DVL-DVR | of the difference between the decelerations DVL and DVR of the left and right driven wheels is equal to or greater than the predetermined value DVo, and the drive wheel with the larger slip amount and the driven wheel with the larger locking tendency are Is located on the same side of the left and right,
The split road is determined (steps S4 to S).
7). Then, when the split road is determined, the engine control target value SET is increased and corrected, and when the above determination is not made, the SET is not corrected and the control is executed as the normal road (step S8). , S9).

<Flow of Slip Control> FIG. 4 shows a flow of slip control during traveling on a split road. That is, when the slip amount of one of the left and right drive wheels (in this case, the left drive wheel) exceeds the control start threshold value due to split road traveling, engine control is started and brake control is started with a delay. Then, on the split road, only one driving wheel causes a large slip and the difference between the slip amounts of the left and right driving wheels is large, so that the braking force is applied to the left and right driven wheels. Then, when it is confirmed that there is a large difference in the locking tendency between the two driven wheels from the deceleration of both driven wheels, and the locking tendency of the left driven wheel is larger, the split road is determined (this In this case, the left side of the road surface is low μ), at which point the engine control target value SET is increased and corrected. Therefore, the engine control amount gradually decreases, and accordingly, the engine output becomes a value corresponding to the depression amount of the accelerator pedal by the driver. However, the brake control target value SBT is not changed.

Therefore, with respect to the left driving wheel rolling on the low μ road surface side, the slip is suppressed mainly by the brake control, but the engine output itself can be increased by reflecting the driver's intention. It will be possible. That is, a high engine output can be applied to the drive wheels on the high μ road surface side where slippage is unlikely to occur, and acceleration of the vehicle can be obtained.

When the vehicle shifts from the split road to a road where the entire road surface is frozen or a road where the entire road surface is exposed to asphalt pavement, the determination of the split road is eliminated, and the engine control target value SET is increased. Is canceled. Therefore, when the vehicle shifts to the frozen road, the engine control is also effectively used for adjusting the slip amount. Further, when the vehicle moves to a road where the asphalt pavement is exposed on the entire road surface, the slip amount of the left and right drive wheels is usually small, and the slip amount is below the control continuation threshold value. Then, if this lower state continues for 1000 msec, the control ends.

With respect to the change of the control mode, the engine control target value SET is changed in the above embodiment, but the engine control amount is changed (the control amount is reduced by correction or the control is changed without changing the SET). A control mode changing method of setting a quantity upper limit value) or a control mode changing method of stopping engine control may be adopted.

Further, regarding the determination of the split road, the lock tendency of the driven wheels may be determined by whether or not only one driven wheel is locked when a predetermined braking force is applied.

[Brief description of drawings]

 The drawings show embodiments of the invention.

FIG. 1 is an overall configuration diagram of a vehicle slip control device.

FIG. 2 is a sectional view of a brake booster.

FIG. 3 is a flowchart of split road determination and control mode change control.

FIG. 4 is a time chart of slip control.

[Explanation of symbols]

 1FL, 1FR Drive Wheel 2 Engine 7FL to 7FR Brake 8 Master Cylinder 9 Engine Output Adjusting Means 51 Control Means 52 Control Mode Changing Means 53 Split Road Judging Means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiaki Anan 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Motor Corporation

Claims (3)

[Claims] Claim: What is claimed is: 1. A driving force applied to both drive wheels such that the slip amounts of the left and right drive wheels with respect to the road surface become a target value.
A control mode suitable for running on a normal road in which the friction coefficients of the rolling road surface portions of the two drive wheels are substantially equal, and a split road in which the friction coefficients of the rolling road surface portions of the two drive wheels are different from each other. Is a slip control device for a vehicle, which is controllable by switching between a control mode suitable for running and running of the vehicle, and which applies a braking force to the left and right driven wheels during the operation of the control means. When the difference in the locking tendency of the driving wheel is large,
When the split road determination means determines that the vehicle is traveling on a split road, and when the split road determination means determines that the vehicle is traveling on the split road, the control mode of the control means is changed to a mode suitable for running on the split road. A slip control device for a vehicle, comprising: a control mode changing means for changing the control mode. 2. The split road determining means applies a braking force to the left and right driven wheels when the control means is in operation and the slip amount difference between the left and right driving wheels is equal to or more than a predetermined value. When the difference in locking tendency between the left and right driven wheels is large and the drive wheel with the larger slip amount and the driven wheel with the larger locking tendency are located on the same side of the left and right sides,
The vehicle slip control device according to claim 1, wherein the determination is made while the vehicle is traveling on a split road. 3. The engine control system for controlling the engine output so that the slip amount of the drive wheels with respect to the road surface has a target value, and the slip amount of the drive wheels with respect to the road surface has a target value. And a brake control system for controlling the braking force applied to the drive wheels, wherein the control mode changing means sets the target value of the engine control system to be lower than that during normal road traveling when it is determined that the vehicle is traveling on a split road. The vehicle slip control device according to claim 1, wherein the slip control device is also increased.