JPH04362456A - Slip control device for vehicle - Google Patents

Abstract

PURPOSE:To lower the slip value of each driving wheel at the time of starting initial slip while brake fluid pressure is being prevented from being frequently switched by shifting control from pressure increasing/decreasing phase to pressure increasing one when the acceleration of each driving wheel is higher than reference acceleration, and thereby executing the differential control of brake fluid. CONSTITUTION:A device is provided with a braking force control means 51 controlling the braking force of each driving wheel with brake fluid controlled, an acceleration detecting means 52 detecting the acceleration of each driving wheel, and with a judging means 53 judging whether or not acceleration detected by the acceleration detecting means 52 is higher than reference acceleration set in advance. When it is judged by the judging means 53 that the acceleration of each driving wheel is higher than reference acceleration in a state that pressure increasing/decreasing phase control is assumed by the braking force control means 51, the braking force control means 51 is allowed to be shifted in control from pressure increasing/decreasing phase to pressure increasing phase.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slip control device for a vehicle that prevents the drive wheels from slipping significantly during acceleration of the vehicle by controlling the torque applied to the drive wheels.

0002

[Prior Art] Conventionally, for example, Japanese Patent Application Laid-Open No. 62-101571
As shown in the publication, in order to prevent the driving wheels from slipping significantly due to excessive driving force acting on the vehicle during acceleration, etc., and reducing acceleration performance, the slip value of the driving wheels is detected. When this slip value exceeds a preset reference value, the engine output is reduced and braking force is applied to the drive wheels to reduce the drive torque of the drive wheels and restore grip. things are being done.

[0003] The braking force control means for controlling the braking force applied to the drive wheels suddenly increases the brake fluid pressure of the drive wheels when the acceleration of the drive wheels exceeds a predetermined value on the acceleration side. The brake fluid pressure is increased and held at a predetermined increased position, and when the acceleration of the driving wheels decreases to a predetermined value, the brake fluid pressure is gradually reduced to terminate braking force control.

0004

[Problem to be Solved by the Invention] When the braking force control means for controlling the braking force applied to the driving wheels is provided with a pressure increasing phase in which the brake fluid pressure is rapidly increased as described above, it is possible to perform slip control. There is an advantage that the brake fluid pressure of the driving wheels can be quickly increased to quickly reduce the slip value of the driving wheels when an initial spin occurs at the start of the process. After the braking force control state is shifted from the pressure increase phase to the pressure reduction phase at the time when the braking force decreases, when the slip value of the driving wheels starts to increase again, the control state of the braking force control means changes from the pressure reduction phase to the pressure increase phase. Move to phase. Therefore, there is a problem in that the control state of the brake fluid pressure changes frequently, such as when the brake fluid pressure changes from a reduced pressure state to an increased pressure state.

[0005] In order to prevent the control state of the brake fluid pressure from frequently changing, the pressure increase phase is limited to the time point when an initial spin occurs, and after that, the control state of the brake force control means is increased. It may be possible to restrict the slip value of the drive wheels so as not to shift to the pressure phase, but with this configuration, if the slip value of the drive wheels suddenly increases due to changes in the running road surface after the initial spin converges, this The problem is that it is not possible to reduce the amount quickly.

The present invention has been made to solve the above-mentioned problems, and it is possible to prevent the brake fluid pressure control state from frequently changing, and to quickly adjust the slip value of the drive wheels when an initial spin occurs. It is an object of the present invention to provide a vehicle slip control device that can reduce the braking force and perform appropriate braking force control corresponding to changes in the running path after the initial spin has converged.

[0007]

[Means for Solving the Problems] As shown in FIG. 1, the present invention increases the brake fluid pressure of the driving wheels when an initial spin occurs when the slip value of the driving wheels exceeds a preset reference value. A slip control device for a vehicle having a pressure increase phase and a pressure increase/decrease phase in which the brake fluid pressure is increased or decreased in accordance with a slip value of a driving wheel after the initial spin converges, the brake fluid pressure being controlled. a braking force control means 51 for applying braking force to the drive wheels; an acceleration detection means 52 for detecting the acceleration of the drive wheels; and a braking force control means 51 for applying braking force to the drive wheels; and determining means 53 for determining whether the acceleration of the drive wheel is greater than the reference acceleration while the braking force control means 51 is executing control of the pressure increase/decrease phase. The braking force control means 51 is configured to shift from the pressure increase/decrease phase control state to the pressure increase phase control state when it is determined by the means.

[0008]

[Operation] According to the present invention having the above configuration, after the initial spin converges, proportional control of the brake fluid pressure is performed in principle by the pressure increase/decrease phase, and the acceleration of the drive wheel is determined by the preset standard in the determination means. When it is confirmed that the brake fluid pressure is larger than the acceleration, the control state of the braking force control means shifts from the pressure increase/decrease phase to the pressure increase phase, and differential control of the brake fluid pressure is executed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Overview of Vehicle Configuration FIG. 2 shows a system diagram of a hydraulic circuit for controlling the engine and wheel brakes of a vehicle to which the vehicle slip control device according to the present invention is applied. This vehicle has left and right front wheels 1L and 1R that serve as driven wheels, left and right rear wheels 2L that serve as driving wheels,
2R, and the driving force of the engine 3 is transmitted to rear wheels 2L, 2R via an automatic transmission 4, a propeller shaft 5, a differential 6, and left and right axles 7L, 7R.

Structure of Automatic Transmission The automatic transmission 4 includes a torque converter 8 as is known in the art.
and a multi-speed gear mechanism 9, and a plurality of solenoids 10 incorporated in the hydraulic circuit of the multi-speed gear mechanism 9.
Shifting is performed by changing the combination of excitation and demagnetization. Further, the torque converter 8 has a hydraulically operated lock-up clutch 11, and is engaged and disengaged by switching between excitation and demagnetization of a solenoid 12 incorporated in the hydraulic circuit. ing.

The solenoids 10 and 12 are controlled in accordance with control signals output from a control unit (not shown) for speed change control. This control unit for speed change control is
The control signals for executing predetermined shift control and lock-up control based on preset shift characteristics and lock-up characteristics as well as detection signals output from the throttle opening sensor and vehicle speed sensor are described above. It is configured to output to solenoids 10 and 12.

Structure of Brake Fluid Pressure Adjustment Mechanism Further, the front wheels 1L, 1R and the rear wheels 2L, 2R are provided with brakes 15a to 15d, respectively.
Brake pressure supply pipes 17a to 17d are connected to the calipers 16a to 16d. The depression force of the brake pedal 18 is then boosted by a hydraulic pressure booster 19 and transmitted to the master cylinder 20, from the first discharge port 21a of the master cylinder 20 through the pipe 17a to the caliper of the left front wheel 1L. Brake fluid pressure is supplied to the caliper 16a, and the brake fluid pressure is supplied from the second discharge port 21b of the master cylinder 20 to the caliper 16b of the right front wheel 1R via the pipe 17b.

The booster 19 is supplied with hydraulic pressure from a pump 23 via a pipe 22, and the excess hydraulic pressure is returned to a reserve tank 25 via a return pipe 24. Branch pipe 2 branched from the above pipe 22
2a is connected to a confluence G with a pipe 27, which will be described later, and an electromagnetic on-off valve 26 is provided in the branch pipe 22a. Further, the boosting hydraulic pressure generated in the booster 19 is supplied to the confluence section G via a pipe 27, and this pipe 27 is provided with an electromagnetic on-off valve 28. There is. A one-way valve 29 is provided in the pipe 27 in parallel with the electromagnetic on-off valve 28, which allows the brake oil to flow toward the confluence G side and prevents the flow in the opposite direction.

Brake pipes 17c and 17d for the left and right rear wheels 2L and 2R are connected to the merging portion G, and this pipe 1
7c and 17d are provided with electromagnetic on-off valves 29A and 30A. A relief passage 31L having an electromagnetic on-off valve 29B is provided downstream of the installation part of the electromagnetic on-off valve 29A, and a relief passage 31L having an electromagnetic on-off valve 29B is provided downstream of the installation part of the electromagnetic on-off valve 30A. A relief passage 31R having a diameter of 30B is provided.

[0015] Each of the on-off valves 26, 28, 29A, 29B
, 30A, 30B constitute a braking force control means 32 for the rear wheels 2L, 2R, and are controlled by a control unit UTR for slip control. When slip control is not performed, as shown in the figure, the on-off valve 26 is closed, the on-off valve 28 is opened, and the on-off valves 29A and 30A are opened. As a result, when the brake pedal 18 is depressed, the boosted hydraulic pressure from the hydraulic pressure booster 19 is applied to the rear wheel brakes 15c and 15d as brake hydraulic pressure through the piping 2.
7. Further, brake fluid pressure is supplied from the master cylinder 20 to the brakes 15a and 15b for the front wheels 1L and 1R.

When performing slip control on the rear wheels 2L and 2R, the on-off valve 28 is closed and the on-off valve 26 is opened in response to a control signal from the control unit UTR. And on-off valves 29A, 29B and 30A
, 30B, the brake fluid pressure is maintained, increased, and decreased by controlling the duty of each brake fluid. That is, the brake fluid pressure is maintained when the on-off valve 26 is open and the on-off valves 29A, 29B, 30A, and 30B are closed. In addition, the on-off valve 29A,
30A is open and the on-off valves 29B and 30B are closed, the brake fluid pressure is increased, and the on-off valves 29A and 30B are closed.
30A is closed and the on-off valves 29B and 30B are open, the brake fluid pressure is in a reduced pressure state. And branch pipe 22a
The brake fluid pressure that has passed through is prevented from acting as a reaction force on the brake pedal 18 due to the bypass action of the one-way valve 29.

Note that when the brake pedal 18 is depressed while slip control is being executed by the braking force control means 32, the brake fluid pressure from the booster 19 is applied to the one-way valve 29 in accordance with the depression of the brake pedal 18. It is supplied to rear wheel brakes 15c and 15d via.

Structure of Engine Generated Torque Adjustment Mechanism The slip control control unit UTR applies braking force to the rear wheels 2L and 2R as described above in order to reduce the torque applied to the rear wheels 2L and 2R when a slip occurs. is applied to execute braking force control, and output control for reducing the driving torque of the engine 3 is executed. This output control is performed by a sub-throttle opening adjustment mechanism 34 disposed in the intake passage 33 of the engine 3. This sub-throttle opening adjustment mechanism 34 consists of a sub-throttle valve 37 disposed upstream of a main throttle valve 36 that is opened and closed by an accelerator pedal 35, and an actuator 38 that drives this sub-throttle valve 37. There is. When a slip occurs, the output of the engine 3 is controlled by opening and closing the sub-throttle valve 37 in response to a control signal output from the control unit UTR to the actuator 38.

Structure of control unit for slip control The control unit UTR for slip control includes a 1L unit for each wheel.
, 1R, 2L, and 2R, the throttle valve sensor 40 detects the opening of the main throttle valve 36, the vehicle speed sensor 41 detects the vehicle speed, and the opening of the sub-throttle valve 37. A sub-throttle valve sensor 42 for detection, a steering angle sensor 43 for detecting the steering wheel angle, a switch 44 used for manually setting the driving mode, etc., and a brake pedal 1.
An output signal from a brake sensor 45 that detects that the brake pedal 8 is depressed is input.

[0020] Depending on the contents of the slip control and each of the above output signals, the control unit UTR
, the slip values of the rear wheels 2L and 2R are calculated, and according to the calculation results, slip control consisting of braking force control of the rear wheels 2L and 2R and output control of the engine 3 is executed as shown in FIG. Ru. In FIG. 3, SET indicates a reference value of the slip value which is a criterion for determining whether or not to start slip control of the rear wheels 2L and 2R. When the vehicle is accelerating, the sub-throttle valve 37 is maintained at the maximum open state in the region up to point A when the slip values of the rear wheels 2L and 2R increase above the reference value SET.
The opening degree Tn of the intake passage 33 is set according to the opening degree of the main throttle valve 36. That is, the accelerator pedal 35
The opening degree Tn of the intake passage 33 is set according to the opening degree TH·B of the main throttle valve 36, which is opened and closed in response to the amount of depression of the main throttle valve 36, and the output control of the engine 3 is executed.

As the rotational speed of the rear wheels 2L and 2R increases, when the slip value exceeds the reference value SET at point A, the actuator 38 is actuated to adjust the opening degree of the sub-throttle valve 37 to that of the vehicle. Feedford control is executed to reduce the initial setting value SM set according to the driving state. As a result, the opening degree of the sub-throttle valve 37 becomes smaller than the opening degree of the main throttle valve 36, and the opening degree Tn of the intake passage 33 is set according to the opening degree of the sub-throttle valve 37. After that, the rear wheel 2L
, 2R according to the slip state of the sub-throttle valve 3.
By feedback-controlling the opening degrees TH and 7, output control of the engine 3 is executed to cause the slip values of the rear wheels 2L and 2R to converge to the target value for slip control consisting of the reference value SET.

Furthermore, from the start point A of the slip control, the slip values of the rear wheels 2L, 2R further increase, and at a point B, when the slip values of the rear wheels 2L, 2R exceed a target value SBT for braking force control, which will be described later, the brakes 15c of the rear wheels 2L, 2R are applied. , 15d, and the brake fluid is supplied to the rear wheels 2L and 15d until the slip value of the rear wheels 2L and 2R becomes equal to or less than the target value SBT.
, 2R are feedback-controlled.

Details of Slip Control Next, details of the slip control by the control unit UTR will be explained based on the flowchart shown in FIG. When the control operation starts, first in step S1, each data is input based on signals from each sensor and switch. Next, in step S2, the slip value S of the rear wheels 2L, 2R is calculated by subtracting the rotational speed VJ of the front wheels 1L, 1R, which are driven wheels, from the rotational speed VK of the rear wheels 2L, 2R, which are driving wheels. When calculating this slip value S, the average value of the rotation speeds of the left and right front wheels 1L and 1R is used as the rotation speed VJ for the driven wheels. In addition, as the rotational speed VK for the drive wheels, the left and right rear wheels 2L, 2
The larger value of the rotational speed of R, or the left and right rear wheels 2
The individual rotational speeds of L and 2R are used.

Next, in step S3, it is determined whether the accelerator is fully closed. If it is confirmed that the accelerator is not in a fully closed state but in a predetermined acceleration state, in step S4, it is determined whether the slip flag SF is 1, that is, whether slip control is currently being executed. Determine whether As a result of this determination, if it is confirmed that slip control is not being executed, a reference value SET for determining whether to start slip control is set in step S5.

That is, as shown by the solid line in FIG. 5, the basic slip value STAO corresponding to the current driving condition is determined from the map of basic slip values STAO for engine output control stored using the maximum friction coefficient μmax of the road surface as a parameter.
Read the value of The map of the gain coefficient VG with vehicle speed as a parameter shown in FIG. 6, the map of the gain coefficient ACPG with the accelerator opening as a parameter shown in FIG. 7, and the map and diagram of the gain coefficient STRG with the steering angle as a parameter shown in FIG. By reading out each gain coefficient from the table of gain coefficients MODEG corresponding to the driving mode selected according to the driver's switch operation shown in 9, and multiplying these values by the above-mentioned basic slip value STAO, the slip control start Find the reference value SET.

Next, in step S6, the rear wheels 2L, 2
It is determined whether the slip value S of R is larger than the reference value SET. If the determination in step S6 is YES, the slip flag SF is set to 1 in step S7, and the output control of the engine 3 is executed in step S8.
In this step, braking force control for the rear wheels 2L and 2R is executed.

If the determination in step S4 is YES and it is confirmed that slip control is currently being executed, the process directly proceeds to step S8 to continue slip control. Further, in step S3, it is determined that the accelerator is fully closed, or in step S6, it is determined that the slip value S of the rear wheels 2L and 2R is less than or equal to the reference value SET for starting slip control, and slip control is executed. If it is confirmed that there is no need, the slip flag SF is set to 0 in step S10, and then the process returns.

Next, the output control of the engine 3 is shown in FIG.
The explanation will be based on the flowchart shown in . First, in step S11, the current slip flag SF
It is determined whether or not the value has changed from 0 to 1, that is, whether or not the present moment is the slip control starting point A shown in FIG. If this determination result is YES, in step S12, as shown in FIG. 11, the initial setting value of the sub-throttle valve 37 is determined from a map set using the vehicle speed and the maximum friction coefficient μmax of the road surface as parameters, that is, the initial setting value at the start of slip control. After reading out the sudden decrease SM of the sub-throttle opening, in step S13, the actuator 38 is operated according to the initial setting value SM, and the sub-throttle valve 3 is
7 to control the opening Tn of the intake passage 33.

Further, if the determination in step S11 is NO and it is confirmed that the slip control has already started, then in step S14 the opening degree TH·M of the sub-throttle valve 37, that is, the rear wheel After reading out the operation amount of the actuator 38 necessary to make the slip value S of 2L and 2R equal to or less than the target value SET, step S
13, the actuator 38 is operated to control the opening degree Tn of the intake passage 33.

Next, in step S15, the rear wheel 2L
, 2R slip value S is the target value SET for slip control.
If it is determined whether the slip value S is still larger than the target value SET,
Return as is. Also, in step S15 above, Y
If it is determined as ES and it is confirmed that the slip value S of the rear wheels 2L and 2R has converged to the target value SET for slip control or less, in step S16, the slip flag SF is set to 0 and the engine 3 Terminate output control.

The braking force control for the rear wheels 2L and 2R is shown in FIG.
2, pressure increase phase control centered on proportional control (phase 0 control), pressure reduction control centered on differential control shown in Figure 13 (phase 1 control), and differential control and proportional control shown in Figure 14. It has three types of control modes including pressure increase/decrease phase control (phase 2 control) in combination with control. In the pressure increase phase shown in FIG. 12 above, Z
indicates a brake fluid pressure retention zone, and is set so that the brake fluid pressure is maintained when the acceleration G of the rear wheels 2L, 2R is on the deceleration side. In the pressure increase phase, Nn indicates the pressure increase zone of the brake fluid pressure, and the larger the absolute value of the acceleration G of the rear wheels 2L and 2R located on the pressure increase side (the larger the value of n), The brake fluid pressure is set to increase at a faster rate.

In addition, in the pressure reduction phase shown in FIG. 13, Pn is such that the larger the absolute value of the acceleration G of the rear wheels 2L, 2R located on the deceleration side (the larger the value of n), the faster the pressure reduction speed. This shows the brake fluid pressure depressurization zone set to Further, the pressure reduction phase is set in the holding zone Z so that the brake fluid pressure is maintained when the acceleration G of the rear wheels 2L, 2R is on the acceleration side.

The pressure increase/decrease phase shown in FIG. 14 includes a pressure increase zone Nn, a pressure decrease zone Pn, and a holding zone Z, and the brake fluid pressure control state is based on the acceleration G of the rear wheel 2L and the rear wheel 2L , 2R and the deviation speed EK are stored as a map set as parameters. The above deviation speed EK is the slip value S of the rear wheels 2L, 2R (rear wheels 2L, 2R).
This value is set based on the difference between the rotation speed VK of the front wheels 1R and the rotation speed VJ of the front wheels 1L and 1R) and the target value SET for slip control.

Braking force control consisting of a combination of the pressure increase phase, pressure decrease phase, and pressure increase/decrease phase is executed based on the flowchart shown in FIG. 15. The braking force control for the rear wheels 2L and 2R is performed independently on the left and right sides, but the contents are basically the same, so only the control operation for the left rear wheel 2L will be described below.

When the above control operation starts, first in step S21, a target value SBT for braking force control is determined. That is, as shown by the broken line in FIG. 5, the basic slip value STB0 for braking force control is determined from a map set using the vehicle speed and the maximum friction coefficient μmax of the road surface as parameters.
By reading out this value and multiplying this value by each gain coefficient shown in FIGS. 5 to 8, a target value SBT for braking force control is calculated.

Next, in step S22, the rear wheel 2L
It is determined whether the slip value S is larger than the target value SBT, and if it is determined as YES, step S2
In step 3, it is determined whether or not braking force control is currently being executed. That is, it is determined whether or not the current moment is in the braking force control state after time B in FIG.

If the determination in step S23 is NO and it is confirmed that the braking force control has not started yet, it is determined that the current time is the point B, and the process proceeds to step S.
At step 24, pressure increase control of phase 0 is started, initial spin convergence control is executed, and a flag indicating the phase state is set to 0 to indicate that the pressure increase phase state is in progress. After that, in step S25, the rear wheel 2
It is determined whether the slip value S of L has converged to the target value SBT for braking force control or less, and if it is determined to be YES, in step S26, a transition is made to the phase 2 pressure increase/decrease control state. , a flag indicating the phase state is set to 2 to indicate that the pressure increase/decrease phase state is present.

If the determination in step S25 is NO, then in step S27 the current rear wheel 2
Deviation EN of slip value S of L and slip deviation at peak time (difference between slip value S of rear wheel 2L at the peak of initial spin and target value SET for slip control) PEN
It is determined whether the ratio is smaller than 0.7. If the determination result in step S27 is NO and it is confirmed that the deviation EN of the current slip value S is a large value close to the slip deviation PEN at the peak, the process returns to step S24 and the phase 0 Continue pressure increase control.

On the other hand, the determination result in step S27 is Y.
ES, and it is confirmed that the deviation EN of the current slip value S is smaller than the slip deviation PEN at the peak time, the transition to the phase 1 decompression control state is made in step S28, and the phase state is changed to A flag indicating this is set to 1 to indicate the decompression phase state.

Next, in step S29, it is determined whether the deviation EN of the above slip value S has become larger than the slip deviation PEN at the peak time, and in step S30, the differential value of the above deviation EN, that is, the above slip deviation EN is determined. It is determined whether the rate of change DENRL of the slip value S of the wheel 2L is greater than 2.0G. And the above step S2
If YES is determined in steps 9 and 30, the process proceeds to step S26 and pressure increase/decrease control is executed.

Further, if the determination results in steps S29 and 30 are both NO, the current slip value S is set to the slip control target value SET in step S31.
If the determination is NO, the process returns to step S28 and the phase 1 pressure reduction control is continued. If the determination in step S31 is YES and it is confirmed that the slip value S has converged to an appropriate value, the braking force control is terminated in step S32.

If the determination in step S23 is YES and it is confirmed that braking force control is already being executed at the present time, then in step S33 the rate of change DEN of the slip value S of the rear wheels 2L is Whether or not the acceleration is greater than the preset standard acceleration of 3.0G, that is, the rear wheel 2
It is determined whether the slip value S of L is in a remarkable increasing tendency. Then, it is determined as YES in the above step S33,
If it is confirmed that the slip value S of the rear wheels 2L is in a marked increasing trend, the process returns to step S24, and phase 0 pressure increase/decrease control is executed.

If the determination in step S33 is NO and it is confirmed that the slip value S of the rear wheel 2L is not in a marked increasing tendency, step S34 determines that the deviation EN of the current slip value S is at the peak. It is determined whether the slip deviation has become larger than the slip deviation PEN. This judgment result is Y
ES, and if it is confirmed that the slip value S of the rear wheel 2L has increased again, the process returns to step S24,
Transition to phase 0 pressure increase control state.

If the determination in step S34 is NO and it is confirmed that the slip value S of the rear wheel 2L is not so large, the current slip value S is determined to be less than or equal to the target value SET for slip control in step S35. Determine whether or not. If the determination in step S35 is NO, the pressure increase/decrease control of phase 2 is continued in step S36. On the other hand, if the determination in step S35 is YES and it is confirmed that the slip value S has converged to an appropriate value, the process proceeds to step S32 and the braking force control is ended.

As described above, the pressure increasing phase of phase 0 and the pressure decreasing phase of phase 1 are used to differentially control the brake fluid pressure according to the slip condition of the rear wheel 2L, and the pressure increasing and decreasing phase of phase 2 is to proportionally control the brake fluid pressure. In a slip control device for a vehicle having a phase, when an initial spin occurs, the pressure increase control of phase 0 is executed to control the rear wheel 2L.
Since the brake fluid pressure is differentially controlled, the brake fluid pressure at the time of occurrence of the initial spin can be rapidly increased, and the slip value S of the rear wheel 2L can be quickly reduced.

After the initial spin converges, the pressure reduction control in phase 1 shifts to the pressure increase/decrease control state in phase 2, thereby proportionally controlling the brake fluid pressure and adjusting the slip value of the rear wheel 2L. Rate of change of S DEN
When the acceleration of the rear wheel 2L displayed by is equal to or higher than a preset reference acceleration (3.0G), the pressure increase control of phase 0 is exceptionally executed and the brake fluid pressure is differentially controlled. This configuration suppresses the occurrence of situations in which the brake fluid pressure frequently switches from a reduced pressure state to an increased pressure state, and also prevents the slip value S of the rear wheel 2L from becoming noticeable after the initial spin settles due to changes in the running road surface, etc. If there is a tendency for the slip value S to increase, it is possible to prevent the slip value S from increasing.

Further, in the above embodiment, when the deviation EN of the slip value S becomes larger than the peak slip deviation PEN after the initial spin converges, the pressure increase control of the phase 0 is executed. Since the brake fluid pressure is configured to be differentially controlled, the slip value S of the rear wheel 2L is
When it is confirmed that the slip deviation EN has gradually increased and the deviation EN has become larger than the slip deviation PEN at the peak,
By quickly increasing the brake fluid pressure through differential control, there is an advantage that the slip value S can be reduced appropriately and quickly.

[0048] In the above embodiment, the braking force control mode consists of three phases: a pressure increase phase in phase 0, a pressure decrease phase in phase 1, and a pressure increase and decrease phase in phase 2.
Although we have explained the case where the control mode is of the following types, after executing the phase 0 pressure increase control when the initial spin occurs,
The configuration of the present invention can also be adopted in a slip control device that directly shifts to the phase 2 pressure increase/decrease control state.

[0049]

As explained above, the present invention has a pressure increase phase in which the brake fluid pressure is differentially controlled according to the slip state of the driving wheels, and a pressure increase/decrease phase in which the brake fluid pressure is proportionally controlled. In a vehicle's slip control system, after the initial spin converges, the brake fluid pressure is controlled by a pressure increase/decrease phase that basically performs proportional control, and if the acceleration of the drive wheels becomes larger than a preset reference acceleration. Since the configuration is configured to shift to the pressure increase phase in which differential control is executed, it is possible to suppress the occurrence of frequent switching of brake fluid pressure from a reduced pressure state to an increased pressure state, and to prevent the running road surface from changing after the initial spin subsides. This has the advantage of being able to prevent the rear wheel slip value from increasing in advance.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a vehicle slip control device according to the present invention.

FIG. 2 is an overall system diagram of the slip control device.

FIG. 3 is a time chart showing the control operation of the slip control device.

FIG. 4 is a flowchart showing the main control operation of slip control.

FIG. 5 is a map showing the relationship between the basic set value of the control reference value and the maximum friction coefficient.

FIG. 6 is a map showing gain coefficients using vehicle speed as a parameter.

FIG. 7 is a map showing a gain coefficient using the accelerator opening degree as a parameter.

FIG. 8 is a map showing gain coefficients using steering angle as a parameter.

FIG. 9 is a chart showing gain coefficients corresponding to driving modes.

FIG. 10 is a flowchart showing an engine output control operation.

FIG. 11 is a map for determining the initial setting value of the subthrottle opening degree.

FIG. 12 is a map of the pressure increase phase.

FIG. 13 is a map of the depressurization phase.

FIG. 14 is a map of the pressure increase/decrease phase.

FIG. 15 is a flowchart showing a braking force control operation.

[Explanation of symbols] 2 Rear wheel (drive wheel) 51 Braking force control means 52 Acceleration detection means 53 Discrimination means

Claims (1)

[Claims] 1. A pressure increase phase in which the brake fluid pressure of the drive wheels is increased when an initial spin occurs when the slip value of the drive wheels exceeds a preset reference value, and the brake fluid pressure is increased after the initial spin has subsided. A slip control device for a vehicle having a pressure increase/decrease phase in which the pressure is increased or decreased depending on a slip value of the drive wheels, and a braking force control means that controls the brake fluid pressure to apply braking force to the drive wheels; The braking force comprises an acceleration detection means for detecting the acceleration of the drive wheel, and a determination means for determining whether the acceleration of the drive wheel detected by the acceleration detection means is larger than a preset reference acceleration. When the determining means determines that the acceleration of the drive wheel is larger than the reference acceleration while the control means is executing the pressure increase/decrease phase control, the braking force control means is changed from the pressure increase/decrease phase control state. A slip control device for a vehicle, characterized in that the device is configured to shift to a pressure increase phase control state.