JPH07165050A - Antiskid control device - Google Patents

Abstract

PURPOSE:To accurately judge the coefficient of friction of a road surface even in the case of judgment based on the wheel speed of the driving wheel of a vehicle. CONSTITUTION:Wheel acceleration is computed on wheel speed, and the quantity of integration slip DELTAn is computed by integrating a difference between wheel speed VW in the case where the wheel speed is less than reference speed and the reference speed VB (steps 330, 335), and moreover the vibration period Tn of the wheel acceleration DVW is computed (step 350). The coefficient of friction is judged on the quantity of integration slip DELTAn and the vibration period Tn, and braking pressure is increased or decreased on the wheel speed VW and the wheel acceleration DVW and the braking pressure is controlled according to the coefficient of friction of a road surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antiskid control device for preventing wheel lock during braking.
The present invention relates to a device for controlling an increase amount of brake pressure according to a friction coefficient of a road surface determined based on a wheel speed, a reference speed and the like.

[0002]

2. Description of the Related Art Conventionally, an anti-skid control device controls the amount of increase in brake pressure according to the friction coefficient of the road surface, and the friction coefficient of the road surface is determined based on wheel speed, reference speed, etc. There is. As a method for determining the friction coefficient of the road surface, for example, the one described in Japanese Patent Laid-Open No. 61-9365 is proposed.

In this apparatus, the difference between the reference speed and the wheel speed is extracted from the depressurization start point at every constant sampling time and integrated, and the integrated value within a certain specific time is compared with a predetermined standard value. The friction coefficient of the road surface was determined according to the comparison result.

[0004]

However, when braking while traveling on a road surface having a low coefficient of friction, the wheel speed may vibrate due to an increase or decrease in the brake pressure, which causes the driving wheels of the vehicle to combine with the driving force from the internal combustion engine. is there. In such a conventional one, when integrated based on the wheel speeds of the drive wheels of such a vehicle, the wheel vibration state of the drive wheels generated on the road surface having a low friction coefficient and the wheel state on the road surface having a high friction coefficient are The integrated values may be almost the same. In such a case, there is a problem that the friction coefficient of the road surface may not be correctly determined.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above problems and to prevent wheel lock by correctly determining the friction coefficient of the road surface even when it is based on the wheel speed of the drive wheels of the vehicle. It is to provide a control device.

[0006]

In order to achieve such an object, the present invention has the following constitution as means for solving the problem. That is, as illustrated in FIG. 1, a wheel speed sensor M1 for detecting a wheel speed, an acceleration calculating means M2 for calculating a wheel acceleration based on the wheel speed, and a brake pressure based on the wheel speed and the wheel acceleration. In the anti-skid control device including the brake pressure control means M3 for controlling the brake pressure according to the friction coefficient of the road surface, the wheel speed when the wheel speed is lower than the reference speed and the reference speed. A slip amount calculating means M4 for calculating an integrated slip amount obtained by integrating the difference between
A cycle calculating means M5 for calculating a vibration cycle of the wheel acceleration, and a friction coefficient judging means M6 for judging the friction coefficient based on the integrated slip amount and the vibration cycle. That is the configuration of the anti-skid controller.

[0007]

The antiskid control device having the above-mentioned structure is
The wheel speed sensor M1 detects the wheel speed, and the acceleration calculation means M2 calculates the wheel acceleration based on the wheel speed. Then, the slip amount calculating means M4 calculates the integrated slip amount obtained by integrating the difference between the wheel speed and the reference speed when the wheel speed is smaller than the reference speed, and the cycle calculating means M5 calculates the vibration cycle of the wheel acceleration. The friction coefficient determination means M6 determines the friction coefficient based on the integrated slip amount and the vibration cycle, and the brake pressure control means M3 increases or decreases the brake pressure based on the wheel speed and the wheel acceleration, and according to the friction coefficient of the road surface. Control the brake pressure.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 2 is a schematic configuration diagram of an anti-skid control device that is an embodiment of the present invention. 1 to 4 are wheels of the vehicle, 1 is a right front wheel, 2 is a left front wheel, 3 is a right rear wheel, and 4 is a left rear wheel. In this embodiment, the driving force of the internal combustion engine 6 is transmitted to the left and right front wheels 1 and 2 via the transmission 8 and the drive shaft 10, and is transmitted to the left and right rear wheels 3 and 4 via the transmission 8 and the drive shaft 12. It is applied to a four-wheel drive vehicle having a configuration.
The present invention is not limited to a four-wheel drive vehicle, but can be applied to a front two-wheel drive vehicle and a rear two-wheel drive vehicle.

Each wheel 1 to 4 is provided with an electromagnetic pickup type or photoelectric conversion type wheel speed sensor 14 to 17 for detecting the respective rotation speed. Further, hydraulic brakes 18 to 21 for braking the rotation of the wheels 1 to 4 are arranged corresponding to the wheels 1 to 4, respectively.

A master cylinder 24, which generates a brake oil pressure in response to a depression operation of a brake pedal 22, is connected to the hydraulic brakes 18 to 21 via respective control valves 26 to 29, and the pressure oil from the master cylinder 24 is connected to the master cylinder 24. Is supplied to the hydraulic brakes 18 and 21 of the right front wheel 1 and the left rear wheel 4, and to the hydraulic brakes 19 and 20 of the left front wheel 2 and the right rear wheel 3.
It is composed of a system.

Each of the control valves 26 to 29 is a three-position valve having the same structure. Each of the control valves 26 to 29 has a pressure increasing position for connecting the master cylinder 24 and the hydraulic brakes 18 to 21, the master cylinder 24 and the hydraulic pressure. A holding position that blocks the brakes 18 to 21, the hydraulic brakes 18 to 21, and the reservoir 3
The pressure reducing position for connecting 0 and 32 can be switched according to a control signal. Reservoir 3
The brake fluid stored in 0, 32 is pumped by pumps 34, 36.
Is driven to return to the master cylinder 24 side.

When the hydraulic pressure of the master cylinder 24 reaches a predetermined value, the control valves 28, 29 and the hydraulic brakes 20, 21 corresponding to the left and right rear wheels 3, 4 have the following pressures. They are connected via proportioning valves 38 and 40 having a well-known structure that prevent the left and right rear wheels 3 and 4 from being locked by reducing the rate of rise.

Further, a brake switch 42 for detecting depression of the brake pedal 22 is provided. The brake switch 42 and the wheel speed sensor 1 are provided.
The control valves 4 to 17 and the control valves 26 to 29 are connected to the electronic control circuit 50. The electronic control circuit 50 includes a well-known CPU 52,
An input / output circuit, here an input circuit 58 and an output circuit 60, which are configured as a logical operation circuit centering on the ROM 54, the RAM 56, etc. and which perform input and output with the outside, are mutually connected via a common bus 62.

The CPU 52 has the wheel speed sensors 14-1.
7, input signal from the brake switch 42 input circuit 5
8 and inputs these signals and ROM 54, RA
Based on the data in M56 and the control program stored in advance, the CPU 52 controls the control valve 26 via the output circuit 60.
Output a signal to ~ 29.

Next, the anti-skid control processing performed in the electronic control circuit 50 described above will be described with reference to the flowchart of FIG. First, it is determined whether it is the anti-skid control start timing (step 1
00). The conditions for starting the anti-skid control are, for example, that the brake switch 42 is on, the wheel speed VW becomes a predetermined speed smaller than a reference speed VB described later, and the wheel acceleration DVW becomes smaller than a preset reference deceleration. For example.

When it is not the start timing, the process waits, and when it is determined that it is the start timing, a process for estimating the road surface friction coefficient μ, which will be described later, is executed (step 110).
Then, the wheel slip amount (= VB-VW) obtained by subtracting the wheel speed VW from the reference speed VB is calculated, and the magnitude of the wheel slip amount is determined (step 120).

When the amount of wheel slip is large, it is determined that slip has occurred, and whether the wheel acceleration DVW is positive or negative is determined (step 130). When the wheel acceleration DVW is negative, the wheels 1 to 4 are locked. When it is determined that there is a risk, the control valves 26 to 29 are switched to the depressurizing position, the hydraulic brakes 18 to 21 are connected to the reservoirs 30 and 32, and the depressurizing mode process for depressurizing the brake hydraulic pressure is executed (step 140).

On the other hand, when the drop of the wheel acceleration DVW stops and the slip of the wheels 1 to 4 tends to recover, the control valves 26 to 29 are switched to the holding position, and the hydraulic brakes 18 to 21 and the master cylinder 24 are blocked. Then, the holding mode process for holding the brake hydraulic pressure is executed (step 150).

Further, by the processing of step 120,
When it is determined that the wheel slip amount (= VB-VW) is small, the occurrence of slip is small, so the control valve 26-
A pressure increasing mode process for switching 29 to the pressure increasing position is executed (step 160). Then, steps 140 to 160
Is executed, it is determined whether it is the anti-skid control end timing (step 170). If it is not the end timing, the processing of step 110 and thereafter is repeatedly executed, and when the brake switch 42 is turned off, the end timing is executed. When it is determined that there is, the processing from step 100 onward is repeated.

In the pressure increasing mode process, as shown in FIG. 4, it is judged whether or not it is the initial pressure increasing output timing after the pressure reduction by executing the pressure reducing mode process (step 162).
When it is the initial pressure increase output timing, the wheel acceleration D
The pressure increase amount Pn is calculated by the following equation based on VW and the friction coefficient μ of the road surface, and the control valves 26-2 are operated according to the pressure increase amount Pn.
The time during which 9 is switched to the pressure increasing position is changed to change the degree of increase in brake pressure (step 164).

Pn = K * DVW where K is a pressure increase amount setting coefficient based on the estimated road surface friction coefficient μ. When it is determined that the road surface friction coefficient μ is high, a large value is used as the pressure increase amount. Is increased, and when it is determined that the friction coefficient μ is low, a small value is set to reduce the pressure increase amount.

On the other hand, when it is not the initial pressure increase output timing, the control valves 26 to 29 periodically switch between the pressure increasing position and the holding position to gradually increase the brake pressure of the hydraulic brakes 18 to 21 (step 166). . When the processing of steps 164 and 166 is completed, the original processing is returned to.

Next, the interrupt process for calculating the wheel speed VW, the wheel acceleration DVW, and the reference speed VB will be described with reference to the flowchart shown in FIG. In this interrupt process, first, the wheel speed VW is calculated by counting the pulse signals from the wheel speed sensors 14 to 17 (step 2).
00), and then the wheel speed VW is differentiated to calculate the wheel acceleration DVW (step 210). Next, in this embodiment, the reference speed VB is set so that the vehicle speed is estimated by using the maximum value of the wheel speeds VW of the wheels 1 to 4 (step 220). Then, after the process of step 220 is completed, the process returns to the original process. The reference speed VB is not limited to the maximum value, but may be such that the vehicle speed is estimated by using an intermediate value obtained by weighting the wheel speeds VW of the wheels 1 to 4.

Next, details of the road surface friction coefficient μ estimation processing (step 110) described above will be described with reference to the flowchart of FIG. First, it is judged whether or not the anti-skid control is being performed (step 300), and when the anti-skid control is not being performed, a time counter, a cycle counter n, a vibration period Tn, and an integrated slip amount Δ which will be described later.
n, the pressure increase amount Pn are respectively cleared, the time over flag and the road surface friction coefficient μ estimation completion flag are reset, and the vibration cycle / integrated slip amount calculation request flag is set (step 305).

When it is judged that the anti-skid control is started by the execution of this processing for the first time (point A in FIG. 11), the time counter for measuring the vibration cycle is incremented (step 310), and the road surface friction coefficient is calculated. It is determined whether or not the estimation is completed depending on whether or not the μ estimation completion flag is set (step 315). When the road surface friction coefficient μ estimation completion flag is set, the process returns to the original processing, and when it is not set, it is determined whether or not the vibration cycle / integrated slip amount calculation request is being made depending on whether or not the flag is set. (Step 320).

At the first time, since the flag is set by the processing of step 305, it is judged that the request is being made,
It is determined whether or not the time counter accumulated by repeatedly executing the process of step 310 has exceeded a preset time (step 325).

When not over, the wheel speed V
It is determined whether W is equal to or higher than the reference speed VB (step 33).
0), immediately after the start of the anti-skid control, since the wheel speed VW is smaller, the integrated slip amount Δn is added to the reference speed VW.
The difference between B and the wheel speed VW is added and again substituted for the integrated slip amount Δn (step 335).

By repeating the processing of steps 300, 310 to 335, as shown by hatching in FIG. 11, the difference (VB) between the wheel speed VW and the reference speed VB when the wheel speed VW is smaller than the reference speed VB. -VW) is integrated to calculate an integrated slip amount Δn. Hereinafter, the calculated integrated slip amount when the wheel speed VW is smaller than the reference speed VB by the first execution of this processing is indicated by Δ1.

When the wheel speed VW becomes equal to or higher than the reference speed VB by executing the processing of step 330, it is determined whether or not the wheel acceleration DVW calculated by the previous processing is 0G or more (step 337). Then, it is determined whether or not the wheel acceleration DVW calculated in this processing is smaller than zero G (step 340).

That is, as shown in FIG. 11, step 33
By the processing of 7,340, steps 325, 330, 337, 340 until the wheel acceleration DVW changes from positive to negative.
When the process of is repeated and changes from positive to negative, the vibration cycle Tn
The time count value counted by the process of step 310 is substituted into. As a result, the vibration cycle T1 between points A and C shown in FIG. 11 is calculated (step 35).
0).

On the other hand, if the wheel speed VW does not exceed the reference speed VB (step 330) or the wheel acceleration DVW does not change from positive to negative by the time when a preset set time elapses (step 325) (337). , 34
In (0), it is determined that the set time has expired by executing the process of step 325, and the time-over flag is set (step 345). Also in this case, the vibration cycle T
The time count value counted by the process of step 310 is substituted for n (step 350).

Next, the cycle counter n for measuring the vibration cycle is incremented (step 355). The cycle counter n is a number counter, and corresponds to the integrated slip amount Δn and the subscripts n and n of the vibration cycle Tn. Then, clear the time counter (step 360),
Since the calculation of the cumulative slip amount Δ1 and the vibration cycle T1 for the first time (n = 1) is completed, the vibration cycle / cumulative slip quantity calculation request flag is reset (step 365).

Since the request flag has been reset, this control process is repeatedly executed, and in the process of step 320, it is determined that the vibration cycle / integrated slip amount calculation request is not being made. Next, as shown in FIG. , Accumulated slip amount △ 1
Is greater than or equal to a preset threshold value, it is determined whether or not the integrated slip amount Δ1 is large (step 40).
0). When it is determined that the integrated slip amount Δ1 is large, it is determined whether or not the vibration cycle T1 is large depending on whether or not the vibration cycle T1 is equal to or more than a threshold value (step 405).

When the integrated slip amount Δ1 is large and the vibration period T1 is also large, slip is likely to occur and the drop of the wheel speed VW is large, so that FIG.
As shown in, the road friction coefficient μ is estimated to be low (step 410). Then, since the estimation of the road surface friction coefficient μ is completed, the road surface friction coefficient μ estimation completion flag is set (step 415). In addition, the above-described processing is performed for each wheel 1
The friction coefficient μ is estimated for each of the wheels 1 to 4.

When it is determined that the vibration cycle T1 is small by executing the processing of step 405, it is determined whether or not the cycle counter n is 1 (step 420). (Step 425) is executed. In this storage processing, as shown in FIG.
It is determined whether or not the wheel speed VW is lower than the reference speed VB (step 426). When the wheel speed VW is lower than the reference speed VB, the pressure increase amount Pn output in the execution of the current cycle is stored (step 426). 427).

Next, the vibration cycle / accumulated slip amount calculation request flag is set (step 428), the time-over flag is reset, and the vibration cycle Tn and the accumulated slip amount Δn are cleared (step 429). Then, the processes of steps 325 to 365 described above are repeated to calculate the vibration cycle T2 and the integrated slip amount Δ2 when the cycle counter n is 2.

That is, as shown in FIG. 12, although the first integrated slip amount Δ1 is large and the drop in the wheel speed VW is large, the vibration cycle T1 is small. It is judged from the influences that the wheels 1 to 4 are in a vibrating state and it is not possible to properly estimate the friction coefficient μ of the road surface, and the processes of steps 325 to 365 are executed again to calculate the vibration period T2 and the integrated slip amount Δ2. To do.

When it is determined in step 426 that the wheel speed VW is equal to or higher than the reference speed VB, the original processing is returned to and the above-described processing is repeated. on the other hand,
When it is determined that the first integrated slip amount Δ1 is small by executing the process of step 400, it is determined whether or not the vibration cycle T1 is large (step 430). When the vibration cycle T1 is large, it is judged whether or not the cycle counter n is 1 (step 435), and since it is the first time,
As shown in FIG. 12, it is estimated that the road friction coefficient μ is low (step 440).

That is, the first integrated slip amount Δ1 is small, and it seems that the road surface does not easily slip from the integrated slip amount Δ1, but the degree of recovery of the wheel speed VW is slow and the vibration cycle T1 is large. Therefore, the road surface and wheels 1 to 4
It is determined that a slip has occurred during the period and the influence of the driving force of the internal combustion engine 6 or the like is exerted, and the friction coefficient μ of the road surface is estimated to be low.

If it is determined by the processing of step 430 that the vibration period T1 is small, the friction coefficient μ of the road surface is estimated to be high (step 445). In other words, the road surface friction coefficient μ is estimated to be high because the integrated slip amount Δ1 is small and it is considered that the road surface is less likely to slip, and the vibration period T1 is small and the wheel speed VW recovers quickly. Thus, when the estimation of the road surface friction coefficient μ is completed by executing the processing of steps 440 and 445, the road surface friction coefficient μ estimation completion flag is set (step 415).

On the other hand, steps 400, 405 and 42 described above.
It is determined that the friction coefficient μ of the road surface cannot be properly estimated by the first integrated slip amount Δ1 and the vibration cycle T1 by the processing of 0,425, and the second processing of steps 325 to 365 is performed again. When the integrated slip amount Δ2 and the vibration cycle T2 are calculated, the processing from step 400 onward is repeatedly executed.

When the integrated slip amount Δ2 is large and the vibration cycle T2 is also large (steps 400, 40)
5), as shown in FIG. 13, it is estimated that the friction coefficient μ of the road surface is low (step 410). Also, the total slip amount △
2 is large, but the vibration period T2 is small (step 40
0,405) and the cycle counter n is 2 (step 420), it is determined whether or not the pressure increase amount Pn-1 stored by the previous process of step 427 is large (step 447).

When the pressure increase amount Pn-1 is large, the wheels 1 to
No. 4 judges that it is in a vibrating state, and judges whether the cycle counter n is 3 (step 450), executes the processing of step 425 described above, and again steps 325 to 36.
The process of step 5 is executed to calculate the third integrated slip amount Δ3 and the vibration cycle T3. When the pressure increase amount Pn-1 is small, the wheels 1 to 4 are vibrating irrespective of the control oil pressure, so that the friction coefficient μ of the road surface is estimated to be low (step 4).
55).

On the other hand, when the integrated slip amount Δ2 is small and the vibration period T2 is large (steps 400 and 430), the cycle counter n is 2 (step 43).
5) It is determined whether the time-over flag is set (step 460). When the time-over flag is not set by the processing of step 345, it is estimated that the road surface is similar to that at the time of executing the processing of step 440, and the friction coefficient μ of the road surface is low, as shown in FIG. 13 (step 465).

When it is determined that the time-over flag is set (step 460), it is estimated that the wheel speed VW is rapidly decreasing and the friction coefficient μ of the road surface is high, as shown in FIG. Yes (step 47)
0). Further, if the integrated slip amount Δ2 is small and the vibration period T2 is also small (steps 400 and 430), it is estimated that the road surface friction coefficient μ is high as described above (step 445).

On the other hand, if the friction coefficient μ of the road surface cannot be estimated from the second integrated slip amount Δ2 and the vibration period T2, the processes of steps 325 to 365 are executed again and the third integrated operation is performed. The slip amount Δ3 and the vibration cycle T3 are calculated. Based on the third integrated slip amount Δ3 and the vibration period T3, the steps 410, 445, 455 and
By executing the processing of 465 and 470, the friction coefficient μ of the road surface is estimated as shown in FIG.

Also at the third time, the accumulated slip amount Δ
3 is large, the vibration cycle T3 is small, and the previous pressure increase amount Pn-
If 1 is large, it is determined in step 450 that the cycle counter n is 3 or more, and the estimation process is executed (step 480). In the estimation process, as shown in FIG. 9, the friction coefficient μ is estimated based on the estimation results of the other wheels 1 to 4.

First, it is determined whether or not the friction coefficient μ of the road surface has already been estimated by executing the above-described processing for the other wheels on the same side of the vehicle body (step 481). If the estimation has already been completed, , It is determined whether or not the cycle counter n of the other wheel on the same side is less than 3 (step 482).

When it is less than 3, since the friction coefficient μ is estimated without being greatly affected by the wheel vibration, it is estimated that the estimation result of the other wheel on the same side has a low road friction coefficient μ. (Step 483),
If it is estimated that the road surface friction coefficient μ is low, it is estimated that the road surface friction coefficient μ is low (step 484).

When the estimation of the friction coefficient μ of the road surface of the other wheel on the same side is not completed (step 481), the cycle counter n of the other wheel on the same side is 3 or more (step 482), the same. When it is estimated that the road side frictional coefficient μ is not low (step 483), the other driving wheels 1 to
It is determined whether or not the estimation of the road surface friction coefficient μ of all four (the other three wheels) has been completed (step 485).

When the estimation of the road surface friction coefficient μ of all the other driving wheels 1 to 4 is not completed, it is estimated that the road surface friction coefficient μ is high (step 486) and all the estimations are completed. In this case, all of the other driving wheels 1 to 4 determine whether the cycle counter n is 3 or more (step 48).
7).

If it is 3 or more, it means that the road surface has a low friction coefficient μ, which is likely to cause wheel vibration.
It is estimated that the friction coefficient μ of all road surfaces is low (step 48
8) If all are not 3 or more, the road surface friction coefficient μ
Is estimated to be high (step 486). When the processes of steps 484, 486, 488 are executed, the flag is set because the estimation of the friction coefficient μ of the road surface is completed (step 489), and the process returns to the original process.

On the other hand, each wheel 1 to
The friction coefficient μ of the road surface is estimated for every 4 wheels.
An example of processing for determining the friction coefficient μ of the road surface used for controlling the brake hydraulic pressure based on the friction coefficient μ of the road surface obtained from the estimation for each of the four will be described with reference to the flowchart of FIG.

First, it is determined whether or not the anti-skid control is being performed (step 500). If the control is not being performed, it is determined that the friction coefficient μ of the road surface is high and the friction coefficient μ determination completion flag is reset (step). 510). On the other hand, when it is determined that the control is being performed, all the wheels 1 to 4 have road friction coefficient μ.
(Step 52)
0), if the estimation is not completed for all the wheels 1 to 4, the original processing is temporarily returned, and if the estimation is completed, it is determined whether or not the determination of the friction coefficient μ is completed (step 5
30). When the flag is set by the processing of steps 550 and 570, which will be described later, it is determined to be completed, the original processing is returned to, and the brake hydraulic pressure is controlled according to the determination result.

If not completed, it is determined whether the front two wheels 1 and 2 are both determined to have a low road friction coefficient μ (step 540), and as shown in FIG.
Regardless of the determination of the rear two wheels 3 and 4, it is determined that the road surface friction coefficient μ is low, and the road surface friction coefficient μ completion flag is set (step 550).

If it is determined that at least one of the front two wheels 1 and 2 has a high road surface friction coefficient μ, the front two
It is determined whether or not both the wheels 1 and 2 are determined to have a high road surface friction coefficient μ (step 560). When both are high, the road surface friction coefficient is determined regardless of the determination of the rear two wheels 3 and 4. It is determined that μ is high, and the road surface friction coefficient μ completion flag is set (step 570).

On the other hand, when the two front wheels 1 and 2 are judged differently (steps 540 and 560), as shown in FIG.
It is determined whether the rear two wheels 3 and 4 are both determined to have a low road surface friction coefficient μ (step 580). After 2
If it is determined that both wheels 3 and 4 are low, it is determined that the friction coefficient μ of the road surface is low, and the friction coefficient μ determination completion flag is set (step 550).

When the determinations of the rear two wheels 3 and 4 are different, for example, it is determined that the vehicle is traveling on a straddling road where the left and right wheels 1 to 4 have different road surface friction coefficients μ, and the road surface friction coefficient μ is determined.
Is determined to be high, and a road surface friction coefficient μ completion flag is set (step 570). As described above, according to the anti-skid control device of the present embodiment, the friction coefficient μ of the road surface is determined based on the integrated slip amount Δn and the vibration period Tn, not only on the integrated slip amount Δn. Even with the wheel speed VW of the driving wheels 1 to 4 where vibration may occur, the friction coefficient μ of the road surface can be appropriately determined. Therefore, even in the case of a four-wheel drive vehicle in which wheel vibrations may occur in the wheels 1 to 4, the friction coefficient μ of the road surface can be determined. Further, even in the case of a front two-wheel drive vehicle or a rear two-wheel drive vehicle, the friction coefficient μ of the road surface can be determined based on the drive wheels, so the determination accuracy is improved.

The execution of the processing of step 210 functions as the acceleration calculation means M2, the execution of the processing of steps 120 to 160 functions as the brake pressure control means M3, and the execution of the processing of steps 330 and 335 performs the slip amount calculation means M4.
Work as. In addition, steps 310 to 330, 337,
The execution of the processing of 340 and 350 functions as the cycle calculating means M5, and the execution of the processing of steps 400 to 570 functions as the friction coefficient determining means M6.

The present invention is not limited to the embodiments as described above, and can be carried out in various modes without departing from the scope of the present invention.

[0061]

As described in detail above, the anti-skid control device of the present invention determines the friction coefficient of the road surface based on the integrated slip amount and the vibration period, and therefore the wheels of the drive wheels that may cause wheel vibrations. Even from the speed, the friction coefficient of the road surface can be appropriately determined. Therefore, even in the case of a four-wheel drive vehicle, the friction coefficient μ of the road surface can be determined, and in the case of a two-wheel drive vehicle, the determination accuracy is improved.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a basic configuration of an anti-skid control device of the present invention.

FIG. 2 is a schematic configuration diagram of an anti-skid control device of the present embodiment.

FIG. 3 is a flowchart showing an example of anti-skid control processing performed in the electronic control circuit of the present embodiment.

FIG. 4 is a flowchart showing an example of pressure increasing mode processing of the present embodiment.

FIG. 5 is a flowchart showing an example of an interrupt process for calculating a wheel speed, a wheel acceleration, and a reference speed in this embodiment.

FIG. 6 is a flowchart showing an example of road surface friction coefficient estimation processing according to the present embodiment.

FIG. 7 is a flowchart showing a part of an example of road surface friction coefficient estimation processing according to the present embodiment.

FIG. 8 is a flowchart showing an example of a storage process of this embodiment.

FIG. 9 is a flowchart showing an example of an estimation process of the present embodiment.

FIG. 10 is a flowchart illustrating an example of determination processing according to the present exemplary embodiment.

FIG. 11 is a time chart of the control signal, wheel acceleration, and wheel speed of the control valve during the anti-skid control of this embodiment.

FIG. 12 is an explanatory diagram illustrating estimation of a friction coefficient of a road surface based on a first integrated slip amount and a vibration period according to the present embodiment.

FIG. 13 is an explanatory diagram illustrating estimation of a friction coefficient of a road surface based on second and third integrated slip amounts and a vibration cycle according to the present embodiment.

FIG. 14 is an explanatory diagram illustrating determination of a friction coefficient of a road surface according to the present embodiment.

[Explanation of symbols]

M1, 14 to 17 ... Wheel speed sensor M2 ...
Acceleration calculation means M3 ... Brake pressure control means M4 ...
Slip amount calculating means M5 ... Cycle calculating means M6 ...
Friction coefficient determination means 1-4 ... Wheel 6 ... Internal combustion engine 18-
21 ... Hydraulic brake 24 ... Master cylinder 26-29 ... Control valve 50 ...
Electronic control circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiro Matsuura 1-1-1, Showa-cho, Kariya city, Aichi prefecture Nihon Denso Co., Ltd.

Claims (1)

[Claims] 1. A wheel speed sensor for detecting a wheel speed, an acceleration calculating means for calculating a wheel acceleration based on the wheel speed, a brake pressure increasing / decreasing based on the wheel speed and the wheel acceleration, and a road surface. In an anti-skid control device including a brake pressure control unit that controls the brake pressure according to the friction coefficient of, the integrated value obtained by integrating the difference between the wheel speed and the reference speed when the wheel speed is lower than the reference speed. A slip amount calculating means for calculating a slip amount, a cycle calculating means for calculating a vibration cycle of the wheel acceleration, and a friction coefficient determining means for determining the friction coefficient based on the integrated slip amount and the vibration cycle, An anti-skid control device characterized by being provided.