JPH03284463A - Anti-skid controller - Google Patents

Abstract

PURPOSE:To carry out appropriate anti-skid control according to various road conditions at the time of deceleration of a vehicle by constituting a road condition judging means so that either of reference value in a comparison means or vehicle acceleration may be compensated according to computed result of a vehicle speed variation ratio computing means. CONSTITUTION:There is provided a road condition judging means M4 which judges a driving road condition according to how many times vehicle acceleration computed from vehicle speed by a wheel acceleration computing means M3 exceeds a prescribed reference value within a prescribed period, and brake fluid pressure is controlled by a pressure control means M5 according to output from the road condition judging means M4, a wheel speed detecting means M1, the wheel acceleration computing means M3, and an estimated vehicle speed computing means M2. With this constitution, there are provided a vehicle speed variation ratio computing means M41 which computes variation ratio of an estimated vehicle speed for a certain period, and a comparison means M42 which compensates either of wheel acceleration or a prescribed reference value according to variation ratio of an estimated vehicle speed for comparison in the road condition judging means M4, which is constituted so as to judge a driving road condition according to the compared result within a prescribed period.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an anti-skid control device that controls the braking force on the wheels and prevents the wheels from locking when braking a vehicle.

[Prior Art] It is well known that when the wheels of a vehicle lock during sudden braking, the vehicle may run unstable or lose steering performance depending on the road surface conditions. For this reason, anti-skid control devices are known that control the braking force by reducing, increasing, or maintaining the brake fluid pressure to the wheel cylinders so that the wheels do not lock during sudden braking.

In anti-skid control devices, in consideration of the fact that when the brake fluid pressure to the wheel cylinders is increased, the wheel speed suddenly decreases just before the friction coefficient μ for the wheels reaches its maximum, acceleration (unless otherwise specified, deceleration) is (including the same hereinafter), and the braking force is controlled so that the slip rate of the wheels becomes around 20%, that is, the maximum friction coefficient is obtained.

In this type of braking force control, when a wheel lock condition is detected, the brake fluid pressure in the wheel cylinder is controlled to be reduced, but when driving on a rough road with uneven roads, depending on the road surface condition. It may be determined that the wheels are showing a tendency to lock, and the brake fluid pressure in the wheel cylinders may be reduced accordingly and the braking distance may be extended. In order to solve this problem, for example, Japanese Patent Application Laid-Open No. 60-2254
Publication No. 8 discloses an anti-pressure sensor that lowers the pressure reduction output sensitivity and increases the pressure increase output sensitivity depending on the level of unevenness of the road surface, such as a good road with gentle unevenness or a bad road with severe unevenness. Skid control devices have been proposed.

[Problems to be Solved by the Invention] However, the above-mentioned conventional device is premised on counting the number of times the wheel acceleration exceeds a certain unevenness level determination reference acceleration. Therefore, if the above reference acceleration is set while the vehicle is running at a constant speed, for example, if the vehicle is decelerating, the level of the reference acceleration will be relatively high depending on the rate of change in vehicle speed, that is, the deceleration. As a result, the number of times exceeding this limit decreases or disappears, making it impossible to accurately judge rough roads.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to enable anti-skid control to be performed accurately in accordance with road surface conditions even when a vehicle is in a decelerating state.

[i! ! Means for Solving the Problem] In order to achieve the above object, the anti-skid control device of the present invention has a configuration that is as shown in FIG.
A wheel cylinder 51 attached to the wheel cylinder 51 to apply braking force, and a wheel speed detection means M1 to detect the wheel speed of the wheel FR.
An estimated vehicle speed calculation means M2 that calculates an estimated vehicle speed based on the wheel speed; a wheel acceleration calculation means M3 that calculates a wheel acceleration from the wheel speed; road surface condition determining means M4, which determines the state of the road surface on which the road is being traveled; and pressure control means M5 for controlling the brake fluid pressure supplied to the brake fluid pressure. The road surface condition determination means M4 includes a vehicle speed change rate calculating means M41 that calculates a change rate of the estimated vehicle speed within a certain period of time, and a change in estimated vehicle speed that calculates either one of the wheel acceleration and a predetermined reference value. It is provided with a comparing means M42 that performs correction and comparison according to the ratio, and determines the state of the road surface on which the vehicle is traveling according to the comparison result of the comparing means M42 within a predetermined time.

[Operation] In the anti-skid control device configured as described above, the rotational speed of the wheel PR, that is, the wheel speed is detected by the wheel speed detection means M1.
detected by. Based on this wheel speed, the estimated vehicle speed calculation means M2 calculates the estimated vehicle speed, and the wheel acceleration calculation means M3 calculates the wheel acceleration.

The calculation result of the wheel acceleration calculation means M3 is supplied to the road surface condition determination means M4, where it is compared with a predetermined reference value, and the condition of the road surface is determined depending on the number of times that this value is exceeded. and,
According to the road surface condition as a result of this determination, and the locked state of the wheel FR determined based on the outputs of the wheel speed detection means M1, estimated vehicle body speed calculation means M2, and wheel acceleration calculation means M3, the pressure control means M5 The brake fluid pressure supplied to the cylinder 51 is controlled. For example, the brake fluid pressure in the wheel cylinder 51 is reduced by the pressure control means M5, and the wheels FR are prevented from being locked.

In the road surface condition determination means M4, the estimated vehicle speed change rate calculation means M2
Based on the output of , a rate of change in the estimated vehicle speed corresponding to the rate of change in the vehicle speed, such as vehicle deceleration, is calculated. Either the wheel acceleration or the reference value is corrected according to the rate of change in the estimated vehicle speed. Then, the two are compared based on this corrected value, and the comparison result within a predetermined time is outputted to the pressure control means as a determination result of the road surface condition.

For example, the above change rate from the reference value (e.g. vehicle deceleration)
The value from which is subtracted is set as the new reference value, so
The number of times the wheel acceleration exceeds this value is calculated under the same conditions as when the vehicle is running at a constant speed.

[Embodiment] Hereinafter, as an embodiment of the present invention, a vehicle equipped with the above-mentioned anti-skid control device will be specifically described.

FIG. 2 shows an anti-skid control device according to an embodiment of the present invention, which includes a mask cylinder 2a and a booster 2b, a hydraulic pressure generating device 2 driven by a brake pedal 3, and wheels FR, FL.

Wheel cylinders 51 to 5 arranged in RR and RL
Pumps 21, 22, reservoirs 23, 24, and electromagnetic valves 31 to 38 are interposed in the hydraulic pressure path connected to 4. Note that the wheel FR indicates the front right wheel as seen from the driver's seat, the wheel FL indicates the front left wheel, the wheel RR indicates the rear right wheel, and the wheel RL indicates the rear left wheel. Diagonal piping is configured.

A solenoid valve 3 is provided in each hydraulic pressure path connecting one output boat of the mask cylinder 2a and each of the wheel cylinders 51 and 54.
1.32 and solenoid valves 33, 34 are interposed, and a pump 21 is interposed between these and the mask cylinder 2a. Similarly, a solenoid valve 35, 36 and solenoid valves 37, 38 are interposed in the hydraulic passages connecting the other output boat of the mask cylinder 2a and each of the wheel cylinders 52, 53, respectively.
A pump 22 is interposed between these and the mask cylinder 2a. The pumps 21 and 22 are driven by the electric motor 20, and brake fluid boosted to a predetermined pressure is supplied to these hydraulic pressure paths.

Therefore, these hydraulic pressure paths are connected to the normally open t-magnetic valve 3133.35.
．． This is the brake fluid pressure supply side for 37. The discharge side hydraulic pressure paths of the normally closed solenoid valves 32 and 34 are connected to the pump 21 via the reservoir 23, and are connected to the normally closed solenoid valve 36.
．． 38 is connected to the pump 2 via the reservoir 24.
Connected to 2. The reservoirs 23 and 24 are each equipped with a piston and a spring, and are connected to solenoid valves 32, 34 and 36.
．． It accommodates the brake fluid that is returned from the pump 38 via the discharge side hydraulic pressure path, and supplies the brake fluid to the pumps 21 and 22 when they are operated.

The solenoid valves 31 to 38 are 2-point, 2-position 1tIifi switching valves, and when the solenoid coils are not energized, they are in the first position shown in FIG.
4 communicates with the hydraulic pressure generating device 2 and the pump 21 or 22. When the solenoid coil is energized, it is in the second position, and each wheel cylinder 51 to 54 is disconnected from the hydraulic pressure generator 2 and the pumps 21 and 22 and communicated with the reservoir 23 or 24. The check valve shown in FIG. 2 allows flow back from the wheel cylinders 51 to 54 and the reservoirs 23 and 24 to the hydraulic pressure generating device 2, and blocks flow in the opposite direction.

By controlling the energization and de-energization of the solenoid coils of these solenoid valves 31 to 38, the brake fluid pressure in the wheel cylinders 51 to 54 can be increased or decreased. That is, when the solenoid coils of the solenoid valves 31 to 38 are de-energized, brake fluid pressure is supplied to the wheel cylinders 51 to 54 from the hydraulic pressure generator 2 and the pump 21 or 22 to increase the pressure, and when energized, the brake fluid pressure is communicated to the reservoir 23 or 24 side. Depressurize.

The electromagnetic valves 31 to 38 are connected to an electronic control device 10, and energization and de-energization of each solenoid coil is controlled. T! I] The motor 20 is also connected to the electronic control device 10 and is driven and controlled thereby. Wheels FR, FL, R
Wheel speed sensors 41 to 44, which are wheel speed detection means according to the present invention, are respectively arranged at R and RL, and these are connected to the electronic control device 10, so that the rotational speed of each wheel, that is, the wheel speed signal, is electronically transmitted. It is configured to be manually operated by the control device 10. The wheel speed sensors 41 to 44 are well-known electric tin induction type sensors consisting of a toothed rotor that rotates as each wheel rotates, and a pickup provided opposite the teeth of this rotor. It outputs a voltage with a frequency proportional to the rotation speed of the motor. Note that instead of this, a Hall IC, optical sensor, etc. may be used.

The electronic control device 10 includes a CPU 14 as shown in FIG.
, a ROM 15, a RAM 16, etc., and is connected to an input port 12 and an output port 13 via a common bus to perform external input/output.
1. The output signals of the wheel speed sensors 41 to 44 are input from the input boat 12 to the CPU 14 via the amplifying circuits 1a to 17d, respectively. Further, a control signal is output from the output port 13 to the electric motor 20 via the drive circuit IBm, and control signals are output to the electromagnetic valves 31 to 38 via the drive circuits 18b to 18i, respectively.

A series of processes for anti-skid control are performed in the electronic control device 10, which will be explained below with reference to FIG. This figure is a flowchart showing the control of one embodiment of the anti-skid control device of the present invention, which is repeatedly executed at predetermined time intervals.

When the power is turned on and the routine is started, first, in step 100, the estimated vehicle speed Vs, which represents the vehicle speed, is initialized.
The wheel speed Vw and wheel acceleration DVw of each wheel are set to zero. Then, in step 102, the wheel speed sensor 4
The wheel speed Vw of each wheel is calculated from the output signals 1 to 44, and the process proceeds to step 104, where the wheel acceleration DV is calculated from this value.
w is calculated. The above estimated vehicle speed Vs is set as the vehicle speed assuming that the vehicle speed is decelerated at a predetermined deceleration based on the wheel speed during braking, and if any of the four wheels exceeds this value, the vehicle speed The value obtained when the vehicle is decelerated again at a predetermined deceleration is set as the vehicle speed.

Next, in step 106, it is first determined whether or not anti-skid control is being performed for the wheels FR, for example. If the anti-skid control is being performed, the process jumps to step 110, and if not, anti-skid*Ja is started in step 108. It is determined whether or not the anti-skid control has started, and if the anti-skid control has started, the process advances to step 110. If the anti-skid control has not started, the process directly jumps to step 120. In step 110, the road surface condition, such as a good road or a bad road, is determined according to a value BNb stored in a frequency buffer, which will be described later. Note that the method for determining the road surface condition is the same as the conventional method, so a description thereof will be omitted. and,
Proceeding to step 112, at least one of pressure reduction and pressure increase is performed depending on the braking situation determined based on the wheel speed Vw, wheel acceleration DVw, and estimated vehicle speed Vs, and the road surface condition that is the determination result of step 110. Set to control mode. In step 114, it is determined whether the control mode is a pressure increase mode or a pressure decrease mode. If the control mode is the pressure increase mode, the process proceeds to step 116 and a pressure increase signal is output. If the control mode is the pressure decrease mode, the process proceeds to step 118 and a pressure decrease signal is output. be done.

There are various control modes, such as dividing the pressure increase mode into a rapid pressure increase mode and a slow pressure increase mode, and any of the control modes may be combined.

The above control mode setting, increase, and pressure reduction signals are output from the wheel cylinders 52 to 5 of the remaining wheels FL, RR, and RL.
The same process is carried out for each of the four wheels FR and FL at step 120.

It is determined whether or not the processing has been performed for all of the RR and RL, and the above routine is repeated until the processing for the four wheels is completed. When this is completed, a new estimated vehicle speed Vs is calculated in step 122, and then in step 1
After the absolute value DVso of the vehicle body deceleration is calculated in step 24, the process returns to step 102. Furthermore, the absolute value DVso of the vehicle body deceleration
is the rate of change of the estimated vehicle speed Vs in a deceleration state within a certain period of time, and is determined as the differential value of the difference between the previous estimated vehicle speed V S (n-11) and the current estimated vehicle speed Vs.

FIG. 5 shows a part of the road surface determination process in step 110 of FIG. 4. First, in step 200, the timer value T is incremented, and in step 202, it is determined whether or not it has exceeded the reference time Tb. Ru. This reference time Tb is a wheel acceleration reference value GB for rough road determination, which will be described later.
(hereinafter simply referred to as reference value GB) is a reference time for counting the number of times the wheel acceleration DVw exceeds the reference value GB, and is set to 0.3 to 0.5 seconds. When it is determined that the timer value exceeds the reference time Tb, the value Nb of the number counter that counts the number of times the wheel acceleration DVw exceeds the reference value GB is stored in step 204 as the value BNb of the number buffer, and step 206 The timer value T is reset at . In step 202, the timer value T is set to the reference time Tb.
If it is determined that the
Proceed to step 8.

In step 208, it is determined whether the count permission flag FNb is set.

The count permission flag FNb is used to enable or prohibit counting for the number counter. When set, it becomes "permitted", and when reset, it becomes "prohibited", and is set according to the determination result of step 216, which will be described later. be done. If the count permission flag FNb is set, proceed to step 210; if not set, proceed to step 2.
Jump to 16. In step 210, a value obtained by adding the absolute value DVso of the vehicle body deceleration to the wheel acceleration DVw is compared with a reference value GB. If this value is less than the reference value GB, the process jumps to step 216. If it is a dog than the reference value GB, the process advances to step 212 and the value N of the number counter is determined.
After b is incremented and the count permission flag FNb is reset in step 214, the process proceeds to step 216. Then, in step 216, (DVw+DVs
It is determined whether the value of o) has fallen below the OG, that is, the acceleration O level, and if it is below, the count permission flag FNb is set, and it is determined whether the value of (DVw+DVsO) exceeds the reference value GB in the next calculation cycle. be done. Wheel acceleration DVw
If is 00 or more, the count permission flag FNb is not set and the process returns to the road surface determination process.

Therefore, in steps 208 to 218, the reference time T
The number of times the value of (DVw+DVso) exceeds the reference value GB during period b is counted. That is, since the wheel acceleration DVw is added by the absolute value DVso of the vehicle deceleration and compared with the reference value GB, even when the vehicle speed calculated as the estimated vehicle speed Vs is on a decreasing trend, the wheel acceleration DVw is It can be correctly compared with a predetermined reference value GB without being influenced by Incidentally, in step 210, the absolute value DVso of the vehicle body deceleration is added to the wheel acceleration DVw and compared with the reference value GB, but the value obtained by subtracting the absolute value DVso of the vehicle body deceleration from the reference value GB and the wheel acceleration DVw It is also possible to compare.

FIG. 6 is a time chart showing the operation in the road surface determination process, in which a reference time Tb is set in the timer value (T). Wheel acceleration DV indicated by a broken line in Fig. 6
The solid line indicates the value obtained by adding the absolute value DVso of the vehicle body deceleration to w. As mentioned above, when the vehicle is decelerating, a bias corresponding to the vehicle body deceleration is applied, so the wheel acceleration DVw may not exceed the reference value GB as shown by the dashed line with respect to the reference value GB shown by the - dotted chain line. If this continues, no judgment will be made to that effect even though the road is rough. In contrast, the solid line (DVw+DVso
) exceeds the standard value GB, and the wheel acceleration D when driving at a constant speed
The relationship is similar to the relationship between Vw and reference value GB. Then, the count permission flag FNb is reset (that is, set to "0") until the rear wheel acceleration DVw that exceeds the reference value GB falls below the OG level, and after falling below the reference value G
It is set (ie, set to "1") until it reaches B. In other words, counting is normally permitted, and once the value of (DVw+DVso) exceeds the reference value GB, it is prohibited, and when it falls below OG, it is permitted again. Then, when the count permission flag FNb is set, the value Nb of the number counter is incremented by 1 each time the reference value GB is exceeded, and the value Nb of the number counter within the reference time Tb is stored as the value BNb of the number buffer. (In the example of Fig. 6, it is "3"). This count result is then used for road surface determination.

In the above embodiment, the vehicle deceleration DVso is used as the rate of change of the estimated vehicle speed Vs within a certain period of time, but the same control may be performed during acceleration using the vehicle acceleration.

[Effects of the Invention] Since the present invention is configured as described above, it has the following effects.

That is, according to the anti-skid control device of the present invention, the road surface condition determination means corrects either the reference value or the wheel acceleration in the comparison means according to the calculation result of the vehicle speed change rate calculation means. Therefore, even when the vehicle is decelerating, for example, anti-skid control can be performed accurately in accordance with various road surface conditions with different unevenness.

can be done.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an overview of the anti-skid control device of the present invention, Fig. 2 is an overall configuration diagram of an embodiment of the anti-skid control device of the present invention, and Fig. 3 is a configuration of the electronic control device of Fig. 2. FIG. 4 is a flowchart showing processing for braking force control according to an embodiment of the present invention, and FIG.
The figure is a flowchart showing the process of road surface determination in one embodiment of the present invention, and FIG. 6 is a time chart for explaining the operation related to road surface determination. 2... Hydraulic pressure control device, 2a... Mask cylinder. 2b...Booster, 3...Brake pedal. 10...Electronic control device. 17a to 17d-・Amplification circuit. 18a-18i...drive circuit. 20...Electric motor, 21.22...Pump. 23.24... Reservoir, 31-38... Solenoid valve. 41 to 44...Wheel speed sensor (wheel speed detection means)
, 51-54...Wheel cylinder. FR, FL, RR, RL...wheels

Claims (1)

[Claims] (1) A wheel cylinder attached to a wheel to apply braking force, a wheel speed detection means for detecting the wheel speed of the wheel, an estimated vehicle speed calculation means for calculating an estimated vehicle speed based on the wheel speed, and the wheel Wheel acceleration calculating means for calculating wheel acceleration from speed; road surface condition determining means for determining the condition of a traveling road surface according to the number of times the wheel acceleration exceeds a predetermined reference value within a predetermined time; and the road surface condition determining means. and pressure control means for controlling the brake fluid pressure supplied to the wheel cylinders according to the determination results and the outputs of the wheel speed detection means, the wheel acceleration calculation means, and the estimated vehicle speed calculation means. In,
The road surface condition determining means is a vehicle speed change rate calculating means for calculating a change rate of the estimated vehicle speed within a certain period of time;
and a comparison means for correcting and comparing one of the wheel acceleration and the predetermined reference value according to the rate of change in the estimated vehicle speed, and according to the comparison result of the comparison means within a predetermined time. An anti-skid control device characterized by determining the condition of a running road surface.