JP3145141B2 - Vehicle slip control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates, to slip degree of the wheel
The present invention relates to a vehicle slip control device that controls a brake pressure to increase or decrease based on a related value (hereinafter, referred to as a slip degree relation value) to suppress an excessive braking force during braking.

[0002] In the present invention, the degree of wheel slip
The joint relation value is a value calculated as : slip degree relation value = (wheel speed / pseudo vehicle speed) × 100 [%] (1) .

[0003]

2. Description of the Related Art Conventionally, for example, Japanese Patent Application Laid-Open No. Sho 62-218257.
As disclosed in Japanese Patent Application Laid-Open Publication No. H10-157, there is known a vehicle slip control device that performs anti-skid brake control for the purpose of preventing the occurrence of a wheel lock or skid state during braking.

When the deceleration of the wheel speed falls below a predetermined threshold value, the slip control device of the vehicle starts anti-skid brake control and firstly holds the increased brake pressure so as not to increase. . Subsequently, when the slip ratio of the wheel in a holding control of the brake pressure falls below a preset threshold, subjected to vacuum control of the brake pressure, while restoring the wheel speed, the slip rate in the pressure reducing control of the brake pressure Is restored to a value equal to or higher than a preset threshold, brake pressure increase control is performed again to reduce the wheel speed. Then, the vehicle speed is reduced according to a predetermined gradient by repeating the above-described brake pressure increasing control for several cycles.

Since the occurrence of wheel lock and slip differs depending on the friction coefficient of the road surface, the threshold value of the deceleration and the threshold value of the slip ratio in the above anti-skid brake control depend on the vehicle speed in consideration of the friction coefficient of the road surface. It is desirable to set a threshold value.

However, the conventional vehicle slip control device estimates the friction coefficient of the road surface from the acceleration and deceleration of the wheel speed in the previous cycle, and in the first cycle immediately after the start of the anti-skid brake control, It has become difficult to estimate the friction coefficient of the tire. Therefore, the first
In the cycle, the road surface condition is set to an appropriate friction coefficient irrespective of the actual road surface condition, and the increase / decrease control of the brake pressure is performed by the threshold value of the deceleration or the threshold value of the slip ratio for the set friction coefficient.

[0007]

In [0007] Slip control system for the conventional vehicles, and sets the road surface condition of the first cycle of anti-skid brake control appropriately, the threshold value or slip ratio of the deceleration relative to the road surface state of its Is set, the following inconvenience occurs in the control of increasing or decreasing the brake pressure. For example, the road surface condition when it is set to a low μ road (a low coefficient of friction road surface), the threshold of the wheel deceleration is set to a relatively large value, the deceleration of the wheel is below the threshold a slight decrease Drop,
Unnecessarily, anti-skid brake control is performed.

On the other hand, the road surface condition is changed to a high μ road (a high friction coefficient).
When the road surface is set to ( road surface) , the above problem is reduced, but the threshold value of the slip ratio is set to a relatively small value, and the timing of the brake pressure reduction control is delayed. In this case, the locked state of the wheels becomes deep, and there is an inconvenience that the wheel speed is not quickly recovered even if the pressure reduction control of the brake pressure is started.

The present invention has been made in view of the above problems, and is more preferable by setting a threshold value of a vehicle deceleration and a threshold value of a slip ratio in a first cycle in consideration of friction coefficients of different road surfaces. It is an object of the present invention to provide a vehicle slip control device capable of performing effective anti-skid brake control.

[0010]

According to the first aspect of the present invention,
Wheel speed detecting means for detecting the rotational speed of the wheel, and a brake
Generates brake pressure according to the pedaling force,
From a brake means for braking the wheels with a rk pressure, and vehicle speed calculating means for calculating a vehicle speed of the vehicles on the basis of the detected wheel speed, the vehicle speed and the calculated detected wheel speed A slip degree relation value calculating means for calculating a value related to the slip degree of the wheel, based on the detected wheel speed
And acceleration calculating means for calculating the acceleration and deceleration of the wheel speed, when the brake pedal is depressed, the rise of the brake pressure based on the stepping force is stopped based on the deceleration of the wheel speed, then, Start decreasing the brake pressure based on the value related to the degree of slip, and stop decreasing the brake pressure based on the deceleration of the wheel speed. Thereafter, increase, hold, decrease and
The above brake to repeat a series of changes in holding multiple times
And a control means for controlling the pressure , the slip control device for a vehicle, at least corresponding to the road surface of high μ road and low μ road.
A first storage unit in which the wheel speed deceleration threshold value is stored in advance, and a characteristic that the threshold value decreases as the vehicle body speed decreases.
Of the value related to the slip degree corresponding to the low μ road
High μ having a threshold and a characteristic of a large decrease rate below this threshold
A second storage unit in which a threshold value of the value related to the degree of slip corresponding to the road is stored in advance, and the control unit performs the first stop increase control of the brake pressure immediately after the start of the braking. When the deceleration of the wheel speed calculated for the high μ road is read from the storage unit and the deceleration of the wheel speed calculated by the deceleration calculation unit is compared with the threshold, and the deceleration of the wheel speed falls below the threshold, Stop the increase in brake pressure,
In the first brake pressure decrease start control immediately after the start of braking,
The threshold value for the low μ road is read out from the second storage means, and the value related to the wheel slip degree calculated by the slip degree relation value calculation means is compared with the threshold value. When the pressure drops below, the brake pressure starts decreasing.

According to a second aspect of the present invention, in the vehicle slip control device, the acceleration / deceleration calculating means calculates
Road surface condition estimating means for estimating a road surface friction coefficient based on the output acceleration and deceleration of the wheel speed ;
The control means controls the brake pressure for the second and subsequent times.
In the previous cycle, the road surface condition estimation means
Calculated by the estimated road surface friction coefficient and the vehicle speed calculation means
From the second storage means on the basis of the determined vehicle speed.
Set the threshold of the value related to the degree of slip according to the state,
The start timing of brake pressure reduction is controlled using the threshold value.
Control .

[0012]

According to the first aspect of the present invention, a brake pedal is provided.
When the brake pedal is depressed, the brake means
The brake pressure is generated, and the braking of the wheels is started. Braking open
At first, the brake pressure responds to the depressed state of the brake pedal.
During the braking, the wheel speed is calculated by the deceleration calculating means.
Is calculated, and the deceleration is recorded in the first storage means.
Decrease below the deceleration threshold for the remembered high μ road
And the brake pressure of the brake means stops increasing,
It is held at the time of the brake pressure.

Subsequently, during the brake pressure holding period, slippage occurs.
A value related to the degree of slip of the wheel by the degree relation value calculation means
Is calculated, and the value is stored in the low μ stored in the second storage means.
It falls below the threshold value of the slip degree relation value for the road
Starts to decrease the brake pressure of the brake
The marking pressure decreases.

After that, the anti-skid brake
Key control, that is, the relationship between wheel speed deceleration and slip degree
Value to increase, hold, decrease and hold the brake pressure
Brake control that repeats a series of changes multiple times is performed
You.

The brake pedal is depressed to start braking.
Immediately after that using the threshold deceleration with respect to the high μ road shake
Since the increase in brake pressure is stopped, anti-skid
Key control start timing is delayed, and
Unnecessary if anti-skid brake control is not required
The control is not performed.

Thereafter, the degree of slip on a low μ road is calculated.
Brake pressure reduction is started using the threshold value of the relationship value
Therefore, the time required to reduce the increased and held brake pressure
Speeding up and the wheels locked due to road conditions
In that case, the lock is released relatively quickly.

According to the second aspect of the present invention, two times
In the control of the brake pressure after the
And the friction coefficient of the road surface estimated by the road surface
The second description is based on the vehicle speed calculated by the vehicle speed calculating means.
Threshold value of slip degree relation value according to road surface condition from storage means
Is set, and the threshold for the start of brake pressure reduction is
Imming is controlled.

That is, control of the brake pressure after the second time
For example, when the friction coefficient of the road surface is large,
When the road surface is estimated to be a high μ road)
The threshold value of the predetermined slip degree related value is set, and the road surface
When the friction coefficient is small (the actual road surface is estimated to be a low μ road)
), The predetermined degree of slip corresponding to the low μ road
The threshold value of the related value is set, and while the brake pressure is
Wheel slip degree related value set according to road surface condition
When the pressure drops below the threshold, the brake pressure starts decreasing.
You.

[0019]

FIG. 2 shows a vehicle provided with a slip control device according to the present invention.

This vehicle has left and right front wheels 1, 1
2 and left and right rear wheels 3 and 4 serving as drive wheels, and the driving force of the engine 5 is transmitted through the automatic transmission 6, the propeller shaft 7, the differential 8 and the left and right axles 9 and 10. It is configured to be transmitted to.

Each of the wheels 1 to 4 has a brake device 11 to 14 comprising a disk 11a to 14a rotating integrally with the wheel and a caliper for controlling the rotation of the disk 11a to 14a by receiving a supply of braking pressure. These brake devices 11 to 14 are driven and controlled by a brake control system 15 described later.

The brake control system 15 has a booster 17 for increasing the depressing force of a brake pedal 16 and a master cylinder 18 for generating a brake hydraulic pressure according to the depressing force increased by the boosting device 17. The front-wheel braking pressure supply line 19 guided from the master cylinder 18 is branched into two paths, and these front-wheel branch braking pressure lines 19a and 19b are connected to the brake devices 11 and 12 of the left and right front wheels 1 and 2, respectively. from together are connected to the caliper 11 b, 12 b, on one front wheel branch brake pressure lines 19a leading to Bureki 11 of the left front wheel 1, and the opening and closing valve 20a of the electromagnetic, the relief valve 20b of an electromagnetic type comprising a first valve unit 20 is arranged, also on the other front wheel branch brake pressure lines 19b leading to the brake device 12 of the right front wheel 2, the on-off valve 21 a similarly electromagnetic and the first valve unit 20 And a second valve unit 21 which is also comprised of an electromagnetic relief valve 21b.

On the other hand, like the first and second valve units 20, 21, an electromagnetic on-off valve 23a is connected to the rear wheel braking pressure supply line 22 led from the master cylinder 18.
And a third valve unit 23 also comprising an electromagnetic relief valve 23b, and the rear wheel braking pressure supply line 22 is connected to the third valve unit 2
The branching pressure lines 22a, 22b for the rear wheels are connected to the calipers 13b, 14b of the brake devices 13, 14 in the left and right rear wheels 3, 4 , respectively.

The relief valves 20b, 21b, 2
The brake oil discharged from 3b is returned to the reservoir tank 18a of the master cylinder 18 via a drain line (not shown).

The first to third valve units 2
The drive units 0, 21, and 23 are independently driven and controlled by the control unit UTR, and the brake device 1 of the left front wheel 1 is operated by the operation of the first and second valve units 20 and 21.
1 and the braking force of the brake device 12 of the right front wheel 2 is variably controlled, and the actuation of the third valve unit 23 variably controls the braking force of the brake devices 13 and 14 of the left and right rear wheels 3 and 4. ing.

The control unit UTR receives a detection signal of a brake switch 25 for detecting whether the brake pedal 16 is depressed and detection signals of wheel speed sensors 26 to 29 for detecting the rotation speed of each wheel. The control unit UTR generates a control signal for anti-skid brake control based on these detection signals, and transmits the control signal to the first to third valve units 2.
0, 21 and 23 to control the braking of the left and right front wheels 1 and 2 and the rear wheels 3 and 4 from slipping.
Perform in parallel for each valve unit.

FIG. 1 is a diagram showing a block configuration in the control unit UTR.

In the figure, reference numeral 30 denotes a vehicle speed calculating means for calculating the vehicle speed during braking. Since the vehicle speed when the wheels 1 to 4 are slipping cannot be accurately detected, the vehicle speed calculating means 30 calculates the pseudo vehicle speed based on the wheel speed Vw obtained from the detection signals of the wheel speed sensors 26 to 29. Calculate Vr. Reference numeral 31 denotes a slip degree for calculating a slip degree relation value of the wheels 1 to 4 defined by the above equation (1).
Ru relationship value calculation means der. Slip degree relation value calculation means
Is calculated using the wheel speed Vw and the pseudo vehicle speed vr.
The slip degree relation value S is calculated by the equation (1) .

Reference numeral 32 denotes acceleration / deceleration calculating means for calculating the acceleration and deceleration of the wheel speed Vw. The acceleration / deceleration calculation means 32 calculates the acceleration AW and the deceleration DW of the wheel speed Vw by converting the result of dividing the difference between the previous value and the current value of the wheel speed Vw by the sampling period Δt (for example, 7 ms) into gravitational acceleration. I do. 33 is a road surface condition estimating means for estimating the friction coefficient of the road surface. The road surface condition estimating means 33 estimates the road surface friction coefficient from the acceleration AW and the deceleration DW of the wheel speed Vw in accordance with the flowchart shown in FIG.

That is, when the control operation for estimating the friction coefficient starts, first, after reading various data, the current anti-skid brake control is performed based on the flag Fabs indicating that the anti-skid brake control is being performed. It is determined whether it is medium or not (# 10, # 11). If the determination result is NO and it is confirmed that the anti-skid brake control is not currently being performed, “3” indicating a high μ road is set to the friction coefficient value MU (# 12).

On the other hand, if it is confirmed in step # 11 that the anti-skid brake control is currently being performed, then in steps # 13, # 14, and # 16,
Deceleration DW or acceleration A of the previous times control the time of the wheel speed Vw
Based on W, road surface conditions are classified into high μ road, medium μ road, and low μ road, and a friction coefficient value MU according to each road surface condition is set.

That is, it is determined whether or not the deceleration DW is smaller than a preset reference deceleration "-20G", and the acceleration AW is set to a preset first reference acceleration "10G" and a second reference acceleration "10G". It is determined whether the acceleration is greater than “20G”. When it is confirmed that the deceleration DW is smaller than the reference deceleration “−20 G”, “1” indicating a low μ road is set to the friction coefficient value MU (# 15), When the acceleration AW is equal to the reference acceleration “20”
If it is confirmed that the value is larger than “G”, “3” indicating a high μ road is set to the friction coefficient value MU (# 17), and
When it is confirmed that the acceleration AW is in the range of “10 to 20 G”, “2” indicating the middle μ road is set to the friction coefficient value MU (# 18).

Returning to FIG. 1, reference numeral 34 denotes a threshold value storage means to be described later.
The threshold value reading means reads out the threshold value of the slip degree relation value and the threshold value of the deceleration from the map stored in 35 . The threshold readout unit 34 controls the threshold value of the slip degree relation value and the threshold value of the deceleration described later based on the determination result from the control cycle determination unit 36 described later, the estimation result from the road surface state estimation unit 33, and the pseudo vehicle speed Vr. Read to means 37. 35 is a map of a threshold value of the wheel speed deceleration for determining the start timing of the anti-skid brake control described later and a map of a threshold value of the slip degree relation value for determining the start timing of the pressure reduction control of the brake pressure. The stored threshold value storage means.

The above-described map of the threshold values of the wheel speed decelerations indicates that the wheel 1 to the wheel 1 in each of the high μ road, middle μ road and low μ road surface conditions.
4 is obtained in advance by experiment or the like as a value at which locking occurs. In the present embodiment, for example, (high μ road threshold, middle μ road threshold, low μ road threshold) = (− 3.0 G, −2. 0G,
-1.5G).

The threshold value map of the slip degree relation value is applied to the first map applied to the brake pressure reduction control in the first cycle and to the brake pressure reduction control in the second and subsequent cycles. The second map is composed of two types of maps. As shown in FIG. 4, the slip degree relation value is set to decrease as the vehicle speed decreases, and the rate of decrease of the threshold value with respect to the vehicle speed in the first map is set smaller than that in the second map. . Further, the second map has a threshold for a plurality of vehicle speed where the friction coefficient of the road surface as a parameter as shown in FIG. 5, each
The threshold value of the slip degree relation value with respect to the vehicle speed is the friction of the road surface
The larger the coefficient (ie, the higher the road surface μ), the smaller the coefficient .

Note that the threshold value of the slip degree relation value in the first map is set at the first cycle immediately after the start of the anti-skid brake control. Is not set as a parameter. However, as a threshold value of the slip degree relation value in the first cycle, a threshold value considering a low μ road has been experimentally obtained in advance, and the rate of decrease of the threshold value with respect to the vehicle body speed is determined by the low μ value of the second map. It is substantially the same as or lower than the rate of decrease of the threshold value on the road. Note that the threshold value on the low μ road of the second map may be used as the first map.

Returning to FIG. 1, reference numeral 36 denotes control cycle determining means for determining whether the anti-skid brake control is in the first cycle. The determination result is input to the threshold reading unit 34, and the threshold reading unit 34 reads a threshold value map of the first or second slip degree relation value from the threshold storage unit 35 based on the determination result.

Reference numeral 37 denotes control means for controlling the increase and decrease of the brake pressure. The control means 37 controls the brake pedal 6
Is depressed, the deceleration of the wheel speed immediately after the start of braking is compared with the threshold value of the deceleration read by the threshold value reading means 34, and when the deceleration of the wheel speed falls below the threshold value, the brake after the pressure increase is increased. A control signal for maintaining the pressure is generated. In addition, the wheel slip degree relation value after increasing and holding the brake pressure is compared with the threshold value of the slip degree relation value read by the threshold value reading means 34, and the wheel slip degree relation value is determined. When it falls below the threshold value, a control signal for reducing the brake pressure is generated.

The control signal is supplied to the brake pressure calculating means 38.
The brake pressure calculating means 38 receives these control signals and generates a braking pressure control signal, and outputs the braking pressure control signal to the first to third valve units 20, 21, 23.
Respectively.

The first to third valve units 20, 2
1, 23 are open / close valves 20a, 2 based on the braking pressure control signal.
1a, 23a and the relief valves 20b, 21b, 23b are controlled to open and close by duty control, respectively, so that the braking force according to the slip state is controlled by the front wheels 1, 2 and the rear wheels 3, 3.
4 is generated.

When the anti-skid brake control is not performed, the first to third valve units 20,
The braking pressure control signal is not output to 21 and 23, and the on-off valves 20a, 21a and 23a are kept open, while the relief valves 20b, 21b and 23b are kept closed. As a result, the brake pressure generated in the master cylinder 18 according to the depression force of the brake pedal 16 is supplied to the brake devices 11 to 14 of the left and right front wheels 1 and 2 and the rear wheels 3 and 4 via the brake pressure supply lines 19 and 22. The braking pressure corresponding to the depression force of the brake pedal 16 is directly applied to the wheels 1-4.

Next, the control operation of the brake pressure of the slip control device according to the present invention will be described with reference to FIG. The control for increasing and decreasing the brake pressure is performed for each of the first to third valve units 20 , 21 , and 23. Here, the first valve unit 20 will be described as an example. Also, wheel speed Vw1, deceleration DW1, acceleration AW1
The number "1" in each code such as the slip degree relationship value S1 is on the left.
This indicates that the item relates to the front wheel 1.

When the brake pedal 16 is depressed at time To, the brake pressure generated by the master cylinder 18 gradually increases, and the braking force causes the wheel speed Vw1 of the left front wheel 1 to increase.
Decreases. The deceleration DW1 of the wheel speed Vw1 is calculated by the acceleration / deceleration calculating means 32, and the threshold reading means 34
Is compared with the deceleration threshold value -3G on the high μ road read out. Then, when the deceleration DW1 of the wheel speed Vw1 falls below the threshold value -3G, the phase shifts from phase 0, which is the non-control state of the anti-skid brake control, to phase 2, and the anti-skid brake control is started.

The anti-skid brake control is started from a phase 2 in which the brake pressure after the pressure increase is maintained.
The first cycle is completed through a phase 3 in which the brake pressure after the pressure increase / retention is reduced and a phase 4 in which the brake pressure after the pressure reduction is maintained. Subsequently, the second cycle is started from the phase 1 in which the brake pressure is increased again from the time Td, and thereafter, when the second cycle is completed through the above-described phases 2 to 4, the same as in the second cycle from the time Te The brake pressure increase / decrease control is repeated for several cycles.

As described above, in the first cycle of the anti-skid brake control, the threshold value of the high μ road is read as the threshold value of the wheel speed deceleration. this is,
Since the coefficient of friction of the road surface cannot be estimated in the first cycle, if the threshold value (−1.5 G) on the low μ road is used, even if the deceleration of the wheel speed slightly decreases, the wheel speed drops below the threshold value. This is for avoiding unnecessary start of the anti-skid brake control.

[0046] Subsequently, the slip degree relationship from the wheel speed Vw1 during Phase 2 in the slip degree relationship value calculating means 31
The value S1 is calculated and compared with the threshold value of the slip degree relation value corresponding to the vehicle speed read from the first map by the threshold value reading means 34. For example, when a threshold value of 90% at high speed is set as the threshold value of the slip degree relation value , the time Tb
When the slip degree relation value S1 falls to 90% or less, the phase shifts from phase 2 to phase 3 and the pressure reduction control of the brake pressure is started. The relief valve 20b of the first valve unit 20 is turned on / off according to a predetermined duty ratio, whereby the brake pressure decreases at a predetermined gradient, the braking force gradually decreases, and the rotational force of the left front wheel 1 recovers.

Subsequently, at time Tc, the wheel speed Vw of the left front wheel 1
When the deceleration DW1 of 1 and the acceleration AW1 become 0, respectively, the phase shifts from phase 3 to phase 4, the brake pressure is maintained at the level after deceleration, and during this phase 4, the wheel speed Vw1 increases again.

The wheel speed Vw1 recovered at time Td
Slip degree relation value S1 of again the slip degree relationship
When the threshold value of the value exceeds 90%, the phase 4 to the phase 1
The anti-skid brake control in the second cycle is started.

Immediately after the transition to the phase 1 of the second cycle, the open / close valve 20b of the first valve unit 20 is set to 100 for the initial rapid pressure increase time Tp2 set based on the duration of the phase 5 in the first cycle. %, And the brake pressure is increased at a steep gradient. Thereafter, the on-off valve 20b is opened and closed at a predetermined duty ratio, and the brake pressure is increased at a gentler gradient than the above gradient.

On the other hand, after the second cycle, the road surface state estimating means 33 uses the wheel speed Vw1 in the previous cycle.
From the deceleration DW1 and acceleration AW1 of the vehicle
Is estimated, and a threshold value of the deceleration and slip degree relation value is set based on the friction coefficient μ of the road surface and the vehicle speed Vr. That is, as the threshold value of the deceleration, a threshold value corresponding to the friction coefficient of the road surface is read from the map stored in the threshold value storage means 35, and the threshold value of the slip degree relation value is stored in the threshold value storage means 3.
A predetermined threshold value is read from the second map stored in 5 using the road surface friction coefficient μ and the vehicle speed Vr as parameters.

When the deceleration DW1 of the left front wheel 1 falls below the deceleration threshold value in the same manner as in the first cycle, the phase shifts from phase 1 to phase 2 to control the holding of the brake pressure after pressure increase. When the slip degree relation value S1 falls below the threshold value of the set slip degree relation value , the phase shifts from phase 2 to phase 3 and pressure reduction control of the brake pressure after pressure increase / holding is performed.

As described above, the threshold value of the deceleration is determined in advance by using the friction coefficient of the road surface as a parameter, and a relatively small threshold value on a high μ road is set as the threshold value for starting the anti-skid brake control. As a result, the deceleration of the wheel speed immediately after the start of braking does not easily fall below the threshold, and unnecessary anti-skid brake control is not performed.

Further, the threshold value of the slip degree relation value in the first cycle after the start of the anti-skid brake control is set to a relatively large threshold value on the low μ road, so that the brake pressure after the pressure increase / hold control is quickly reduced. Because it was
The locked state of the wheel is quickly released, and the lock of the wheel can be prevented from becoming deep even when the actual road surface state is a low μ road.

Also, after the start of braking, the friction coefficient of the road surface is estimated, and the threshold value of the slip degree relation value is set based on the estimated friction coefficient and the vehicle speed. Suitable anti-skid brake control can be performed. For example, when the vehicle body is running at a low speed, the threshold value of the slip degree relationship value becomes smaller as the vehicle travels on a high μ road, and the pressure reduction timing of the brake pressure is delayed, so that the locked state of the wheels becomes longer. It will be stopped in between.

In the above embodiment, the slip degree relation
Although the threshold value was continuously changed with respect to the vehicle speed,
The vehicle speed may be divided into regions, and the threshold value may be changed stepwise in each divided region.

[0056]

As described above, according to the present invention, among the threshold values of the wheel speed deceleration preset according to the friction coefficient of the road surface, the smaller threshold value on the high μ road is used to start the anti-skid brake control. Since the threshold value is set, the anti-skid brake control is not unnecessarily performed after the start of braking.

Also, the control threshold value for the brake pressure reduction control immediately after the start of the anti-skid brake control is set to a relatively large threshold value for a low μ road among the threshold values of the slip degree relation value preset according to the road surface friction coefficient. Is set as the brake pressure reduction start threshold value immediately after the start of the anti-skid brake control, so that the locked state of the wheel is released quickly and the lock of the wheel can be prevented from becoming deep.

Also, two times of anti-skid brake control
In the subsequent brake control, the threshold value of the slip degree relation value according to the road surface friction coefficient is set, so that a suitable brake pressure reduction control can be performed according to the road surface friction coefficient.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a configuration of a vehicle provided with a slip control device according to the present invention.

FIG. 3 is a flowchart for estimating a friction coefficient of a road surface.

FIG. 4 is a diagram showing a threshold value of a slip degree relation value with respect to a vehicle speed;

FIG. 5 is a diagram showing a threshold value of a slip degree relation value with respect to a vehicle speed using a road surface friction coefficient as a parameter;

FIG. 6 is a diagram for explaining an operation of anti-skid brake control by the slip control device according to the present invention.

[Explanation of symbols]

1, 2 front wheel 3, 4 rear wheel 11 to 14 brake device (brake means) 15 brake control system 16 brake pedal 17 booster 18 master cylinder 19, 22 brake pressure supply line 20, 21, 23 valve unit 26 to 29 wheels Speed sensor 30 vehicle speed calculating means 31 slip degree relation value calculating means 32 acceleration / deceleration calculating means 33 road surface state estimating means 34 threshold reading means 35 threshold storing means 36 control cycle determining means 37 control means 38 brake pressure calculating means UTR control unit

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Fumio Kageyama 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Inside Mazda Co., Ltd. (56) References JP-A-62-241754 (JP, A) JP-A-1 -275255 (JP, A) JP-A-63-45370 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60T 8/00-8/96

Claims (2)

(57) [Claims] 1. A wheel speed detecting means for detecting a rotational speed of a wheel, and a brake pressure corresponding to a depression force of a brake pedal is generated.
Brakes that use the brake pressure to brake the wheels
Calculating a rk in unit, a vehicle speed calculating means for calculating a vehicle speed of the vehicles on the basis of the detected wheel speed, a value related from the vehicle speed and the calculated detected wheel speed to the slip degree of the wheel Means for calculating a slip degree relationship value to be detected and a detected vehicle
Acceleration / deceleration calculation means for calculating the acceleration and deceleration of the wheel speed based on the wheel speed, and the brake pedal is depressed.
If the brake pressure rises
Stop based on the deceleration of the wheel speed.
Reduce the brake pressure based on the value related to the degree of lip.
And start based on the above wheel speed deceleration.
To stop the decrease in the brake pressure, and thereafter increase,
Repeat a series of changes of hold, decrease and hold multiple times
To a slip control system for a vehicle and a control means for controlling the braking pressure, at least a high μ road and a low μ road
A first storage unit in which the threshold value of the wheel speed deceleration is stored in advance corresponding to the road surface; and the slip degree corresponding to a low μ road having a characteristic of decreasing with a decrease in the vehicle body speed.
The threshold of the value related to
Related to the above slip degree corresponding to high μ road
Bei the second storage means and the threshold value was is stored in advance
For example, the control means, the increase stop control of the first brake pressure immediately after the start of braking, the from the first storage means reads out the threshold deceleration with respect to a high μ road, a wheel speed calculated by the deceleration calculating means When the deceleration of the wheel speed falls below the threshold value by comparing the deceleration of the wheel speed with the threshold value, the brake pressure increase is stopped, and in the first brake pressure reduction start control immediately after the start of braking, the second The threshold value for the low μ road is read from the storage means, and the value related to the wheel slip degree calculated by the slip degree relation value calculation means is compared with the threshold value, and the value related to the slip degree falls below the threshold value. And a step of starting the reduction of the brake pressure. 2. The vehicle slip control device according to claim 1 , wherein said wheel calculated by said acceleration / deceleration calculation means.
Road condition estimating means for estimating a road surface friction coefficient based on the speed acceleration and deceleration ;
In the control of the brake pressure after the first time, the previous
Of the road surface estimated by the road surface condition estimation means
The coefficient of friction and the vehicle speed calculated by the vehicle speed calculating means
From the second storage means based on the road surface condition.
Set a threshold value for the value related to the
A vehicle slip control device for controlling a start timing of a brake pressure decrease .