JP2003019953A - Antiskid control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain a shortage of braking force by excessive pressure reduction at antiskid control time in low speed travel. SOLUTION: In antiskid control, either of a pressure reducing mode and a holding mode is determined according to a control map on the basis of a wheel speed (S7), and when set in a pulse pressure increasing mode (S11), pressure is gently increased after suddenly increasing pressure. When the pulse pressure increasing mode is selected and a vehicle traveling speed is a preset speed or less (S15), sudden pressure increase time is lengthened (S16), and a pressure increase gradient by leveling a sudden pressure increase and a gentle pressure increase is steepened thereby, and the shortage of the braking force caused by the excessive pressure reduction at antiskid control time in the low speed travel can be restrained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-skid device, and more particularly to avoiding insufficient braking force due to excessive pressure reduction during low speed running.

[0002]

2. Description of the Related Art An antiskid device is generally constructed as follows. (A) hydraulic pressure source, (b) reservoir,
(C) An increase that is provided between the hydraulic pressure source and the reservoir and the brake cylinder of the brake device that suppresses rotation of the wheels of the vehicle, and at least increases the hydraulic pressure of the brake cylinder by communicating the brake cylinder with the hydraulic pressure source. A hydraulic pressure control valve device that switches between a pressure state and a depressurized state in which the brake cylinder is connected to the reservoir to reduce the hydraulic pressure in the brake cylinder; and (d) a wheel speed acquisition unit that acquires the speed of the wheel, e) traveling speed acquisition means for acquiring the traveling speed of the vehicle; and (f) switching the hydraulic control valve device based on the wheel speed and the traveling speed acquired by the wheel speed acquisition means and the traveling speed acquisition means, respectively. And a control means for controlling the slip of the wheels within an appropriate range.

In such an anti-skid device, there is a tendency that the pressure is excessively reduced when the vehicle runs at a low speed and the braking force becomes insufficient. There are various causes, but for example, in the anti-skid device described in Japanese Patent Laid-Open No. 3-292247, the fact that the traveling speed is acquired from the wheel speed causes the excessive decompression. When the traveling speed is acquired from the wheel speed, it is acquired based on the fastest wheel speed of the four wheel speeds and the deceleration detected by the longitudinal acceleration sensor. Wheel speeds fluctuate due to pressure fluctuations,
Along with that, the traveling speed also changes considerably. Then, if the traveling speed and the wheel speed become low, the influence of these fluctuations greatly appears and the slip ratio greatly fluctuates, and it is judged that the slip ratio actually exceeds the proper range, but it is judged that the slip rate is reduced. Therefore, the pressure tends to be excessively reduced. Therefore, in the anti-skid device described in the above publication, when the traveling speed is equal to or lower than the set value, based on the deceleration detected by the longitudinal acceleration sensor when the traveling speed is equal to or lower than the set value, The traveling speed is configured to be acquired regardless of the wheel speed, and the pressure is not excessively reduced.

[0004]

However, there are various causes other than the cause described in the above publication as the cause of excessive decompression during low speed traveling. For example, one of the causes is that the wheel speed is acquired based on the detection result of the pulse rotation sensor. The pulse-type rotation sensor rotates with a wheel and has a rotor having a large number of teeth on its periphery, a coil and a permanent magnet attached to the vehicle body, and converts an AC voltage generated in the coil as the rotor rotates into a pulse signal. With a waveform shaper, the wheel speed can be calculated from the cycle of the pulse signal. However, as will be described later in detail in the section of Examples, as the traveling speed becomes lower, the pulse period becomes longer and the delay in detecting the wheel speed becomes larger,
This contributes to excessive depressurization.

Excessive pressure reduction by using this pulse type rotation sensor cannot be prevented by the means described in the above publication. This is because even if the acquisition of the traveling speed based on the wheel speed is stopped, if the wheel speed is acquired based on the detection result of the pulse type rotation sensor, the excessive decompression due to the delay in the detection of the wheel speed cannot be avoided. The present invention is
It is an object of the present invention to provide an anti-skid device capable of avoiding insufficient braking force as much as possible regardless of the cause of excessive decompression during low-speed traveling.

[0006]

In order to solve the above-mentioned problems, the invention according to claim 1 is, as shown in FIG. 1, a hydraulic pressure source 1, (b) reservoir 2, (c). Control means for anti-skid device including hydraulic pressure control valve device 3, (d) wheel speed acquisition means 4, (e) traveling speed acquisition means 5 and (f) control means 6 for controlling hydraulic pressure in the brake cylinder of the brake device 6, (1) means for controlling pressure increase by rapidly increasing the hydraulic pressure of the brake cylinder and then gradually increasing it,
(2) When the traveling speed is less than or equal to the set value, the time for the rapid pressure increase is made longer than when the traveling speed exceeds the set value, so that the pressure increase gradient that equalizes the sudden pressure increase and the slow pressure increase is set. The purpose of the present invention is to include a pressure increasing control means 7 for low speed traveling which is made steeper than when the value exceeds the set value. Further, according to the invention of claim 2, the low speed traveling control means sets the pressure increasing gradient of the hydraulic pressure of the brake cylinder such that the traveling speed is equal to or less than a set value and the previous depressurizing time of the hydraulic pressure of the brake cylinder is set. The gist of the invention is to make it steeper when the time is longer than the time, and the invention of claim 3 is a means for controlling the low-speed traveling time to make the pressure increase gradient of the hydraulic pressure of the brake cylinder steeper as the decompression time becomes longer. The main point is to include.

The pressure increasing gradient of the hydraulic pressure of the brake cylinder is set, for example, so that the pressure increasing time for each time is set long when the pressure increasing is performed by switching between the pressure increasing state and the pressure reducing state of the hydraulic pressure control valve device 3. Alternatively, the depressurization time for each time may be set short, or the pressure may be increased only by increasing the pressure. Further, the pressure increase gradient may be made steep continuously while increasing the brake cylinder pressure, or may be made steep only when the pressure increase is started. The same applies to the case where the hydraulic pressure control valve device 3 is a device capable of switching between a pressure increasing state, a holding state and a pressure reducing state, and the pressure increasing is performed by switching between the pressure increasing state and the holding state. Further, when the pressure increase is performed by the rapid pressure increase and the slow pressure increase, it is possible to substantially abruptly increase the rapid pressure increase time and shorten the gentle pressure increase time. By doing so, the gradient of the entire pressure increase consisting of the rapid pressure increase and the slow pressure increase is substantially increased.

[0008]

In this way, when the traveling speed is equal to or lower than the set value, if the pressure increase gradient of the hydraulic pressure in the brake cylinder is made steep, even if the pressure is excessively reduced, the excessive decrease in the brake cylinder pressure is promptly recovered. be able to.

When the wheel speed becomes equal to or lower than the set value, it is possible to make the pressure increasing gradient steep in the pressure increasing state to compensate for the excessive decrease of the brake cylinder pressure. The running speed usually decreases as soon as the braking is started and then begins to decrease. After the running speed reaches the set value or less, the pressure increase gradient is steep until the anti-skid control is released. . On the other hand, since the wheel speed increases and decreases due to fluctuations in the brake cylinder pressure, the wheel speed may once drop below the set value and then exceed the set value again. In that case, the control for making the pressure increase gradient steep is stopped. However, eventually, the wheel speed does not exceed the set value, and the control for making the pressure increase gradient steep continues. Therefore, it is also within the technical scope of the present invention to make the pressure increase gradient steep when the wheel speed is equal to or lower than the set value.

[0010]

As described above, according to the present invention, even if the pressure is excessively reduced during low-speed traveling, the excessive decrease in the brake cylinder pressure is rapidly recovered by the steep pressure increase gradient. The shortage of the braking force is small, the extension of the braking distance can be suppressed, and the vehicle can be stopped satisfactorily. Further, since the present invention compensates for the shortage of the brake cylinder pressure by making the pressure increase gradient steep, the cause of the excessive reduction of the brake cylinder pressure is the wheel speed and the traveling speed as described in the above publication. Insufficient braking force can be avoided even if there is a change in speed or if there is a delay in obtaining wheel speed due to the use of a pulse rotation sensor.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an anti-skid device for a hydraulic brake device for a four-wheeled vehicle will be described in detail below with reference to the drawings. In FIG. 2, 10 is a tandem master cylinder as a hydraulic pressure source. A brake pedal 1 is provided to the master cylinder 10 via a booster 12.
4 are connected, and hydraulic pressures of the same height are generated in the two independent pressurizing chambers of the master cylinder 10 in response to the depression operation of the brake pedal 14. Reference numeral 16 is a reservoir that is attached to the master cylinder 10 and supplies brake fluid to the master cylinder 10.

The hydraulic pressure generated in each pressurizing chamber of the master cylinder 10 is applied to the left and right front wheels 20, 22 and the left and right rear wheels 2, respectively.
It is supplied to the front brake cylinders 30 and 32 and the rear brake cylinders 34 and 36 of the brake devices provided in 4 and 26, respectively. The hydraulic brake device according to this embodiment is of a front / rear two-system type. Since the front and rear brake systems have almost the same basic configuration, the same reference numerals will be given to the front and rear systems for those that perform the same action, and the front wheel brake system will be mainly described, and the brakes for the rear wheels will be described below. The system will be supplemented as necessary.

In the middle of the main fluid passage that connects the master cylinder 10 and the front brake cylinders 30 and 32, there are provided two electromagnetic control valves 40 as hydraulic pressure control valve devices corresponding to the front brake cylinders 30 and 32, respectively. The main fluid passage is divided into a master cylinder side passage 42 and a brake cylinder side passage 44. In the brake system of the rear wheels 24, 26, the electromagnetic control valve 40 has the rear brake cylinder 34,
It is common to 36.

Each electromagnetic control valve 40 is a switching valve capable of switching among three states of a pressure increasing state, a holding state and a pressure reducing state. As shown in FIG. 2, the pressure-increased state is such that the master cylinder side passage 42 is connected to the corresponding brake cylinder side passage 44.
And the hydraulic pressure of the corresponding front brake cylinders 30, 32 is increased by the brake fluid supplied to the master cylinder side passage 42. The holding state is a state in which all of the master cylinder side passage 42, the brake cylinder side passage 44, and the reservoir passage 48 are shut off to keep the hydraulic pressure of the corresponding front brake cylinders 30, 32 constant. In the depressurized state, the corresponding brake cylinder side passages 44 are communicated with the common reservoir 50 via the reservoir passages 48, and the brake fluid flows out from the front brake cylinders 30, 32 to the reservoir 50 to cause the front brake cylinders 30, This is a state in which the hydraulic pressure of 32 is reduced.

The brake fluid contained in the reservoir 50 is pumped up by the pump 52. The pump 52 is driven by the motor 54, and the brake fluid in the reservoir 50 is relieved of pulsation by the accumulator 56 while the check valve 58 is being provided.
It is supplied to the master cylinder side passage 42 via a pump passage 60 provided with. A reservoir 50 is provided before and after the pump 52.
A pair of check valves 64 whose forward direction is from the accumulator 56 to the accumulator 56 are provided, and the brake fluid is stored in the reservoir 50.
It is designed not to flow back into.

Further, bypass passages 70 bypassing the respective electromagnetic control valves 40 are connected between the master cylinder side passage 42 and the brake cylinder side passage 44, and the front brake cylinders 30 are provided in the middle of the bypass passages 70. Check valves 72 whose forward direction is the direction from the 32, 32 side to the master cylinder 10 side are respectively provided. Therefore, when the depression of the brake pedal 14 is released and the master cylinder hydraulic pressure is reduced, the front brake cylinders 30 and 32 cause the electromagnetic control valves 4 to move.
Bypassing 0, the brake fluid is promptly returned to the master cylinder 10.

The switching of the electromagnetic control valve 40 is performed by the control device 80.
Done by The control device 80 is mainly composed of a microcomputer, and includes the left front wheel 20 and the right front wheel 2.
The slip states of the wheels 20, 22, 24, 26 are estimated from the output signals of the rotation sensor 82 that detects the respective rotation speeds of 2 and the average rotation speeds of the left and right rear wheels 24, 26, respectively, and the electromagnetic control valves 40 By controlling the amount of current supplied to the solenoid 84, the electromagnetic control valve 40 is controlled to the above-mentioned three.
By switching between the two states, the slip ratios of the left front wheel 20 and the right front wheel 22 and the average slip ratios of the left and right rear wheels 24, 26 are controlled to appropriate values. The rotation sensor 82 is a pulse type rotation sensor, and the number of pulses corresponding to the wheel speed is supplied to the control device 80. Further, a brake switch 86 that detects the depression of the brake pedal 14 is connected to the control device 80.

As shown in FIG. 3, a flag F and a counter 92 are provided together with a working memory in the RAM of the microcomputer which is the main body of the controller 80. Further, the control mode selection map for anti-skid control shown in FIG. 4 is stored in the ROM of the microcomputer. This control mode selection map is a pressure reduction or a pressure increase depending on whether the wheel speed V _W is larger than the control reference speeds V _SN and V _{SH and} whether the wheel acceleration V _W ′ is larger than the reference accelerations G ₁ and G ₂ . This is a map for selecting whether to hold. The control reference speed V _SH and the control reference speed V _SN are calculated by multiplying the traveling speed of the vehicle by a certain ratio, and the control reference speed V _SH is set to a value lower than V _SN .
Further, the reference acceleration G ₂ is a positive value, and the reference acceleration G ₁
Is a negative value, and these are preset to constant values.

In the control mode selection map, the pressure reducing mode is a mode in which the brake cylinder pressure is rapidly reduced by keeping the electromagnetic control valve 40 switched to the pressure reducing state. The holding mode is the holding state of the electromagnetic control valve 40. In this state, the brake cylinder pressure is maintained at a constant height. The pulse increasing mode is a mode in which the brake cylinder pressure is gradually increased by alternately switching the electromagnetic control valve 40 between the pressure increasing state and the holding state, and the time between the pressure increasing state and the holding state is set in advance. Has been done.

Further, the ROM stores an anti-skid control routine shown by the flowchart in FIG. Hereinafter, the anti-skid control will be described based on this flowchart.

First, in step 1 (hereinafter abbreviated as S1; other steps are the same), the detected value of the rotation sensor 82 is read, and the wheel speed (wheel peripheral speed) V _W , wheel acceleration V _W ′, The traveling speed Vs, the vehicle deceleration and the control reference speeds V _SN and V _SH are calculated. The running speed Vs is always estimated to be the fastest speed among the four wheel speeds, and after the deceleration of the fastest wheel exceeds a preset upper limit value, the deceleration is set to the upper limit value. The traveling speed Vs is fixedly calculated. Next, S2 is executed and it is determined whether or not the flag F is set. The determination result is NO, and it is determined in S3 whether or not the antiskid control start condition is satisfied.

In this embodiment, the antiskid control start condition is that the brake pedal 14 is depressed.
That is, the wheel speed V _W is equal to or lower than the control reference speed V _SN , and the wheel acceleration V _W ′ is equal to or lower than the reference acceleration G ₁ . If these anti-skid control start conditions are not satisfied, the determination result in S3 is NO, the flag is reset in S6, the counter 92 is cleared, the electromagnetic control valve 40 is switched to the pressure increasing state, and the routine is executed. Ends.

If the anti-skid control start condition is satisfied, the determination result in S3 is YES, and the flag F is determined in S4.
After is set, S5 is executed and it is determined whether or not the antiskid control termination condition is satisfied. The anti-skid control termination condition is that the depression of the brake pedal 14 is released. If the termination condition is satisfied, the determination result of S5 is YES, and after the execution of S6, the execution of the routine is terminated.

If the anti-skid control start condition is satisfied and the anti-skid control end condition is not satisfied, S7 is executed and the control mode is selected. The control mode is selected according to the control mode selection map shown in FIG. 4 based on the wheel speed V _W and the wheel acceleration V _W ′ calculated in S1.

After the selection, S8 is executed and it is determined whether the selected control mode is the pressure reducing mode. If the pressure reducing mode is selected, the determination result of S8 is YES and S9
After the count value C of the counter 92 is increased by 1, the pressure reduction command signal is output in S10, whereby the electromagnetic control valve 40 is switched to the pressure reduction state, the brake cylinder pressure is reduced, and the wheel slip is reduced. To be made. While the decompression mode is selected, S1, S2, S
5, S7 to S10 are repeatedly executed, and the counter 92 measures the depressurization time.

When the wheel rotation is restored and the pulse increasing mode or the holding mode is selected, the determination result of S8 is NO and S11 is executed to determine whether or not the pulse increasing mode is selected. . If it is not the pulse increasing mode, it is the holding mode, and the determination result of S11 is NO,
In S12, the hold command signal is output and the electromagnetic control valve 4
0 is switched to the holding state.

On the other hand, if the selected control mode is the pulse increasing mode, the determination result of S11 is YES,
S13 is executed and the rapid pressure increase time at the start of pressure increase is calculated. As described above, the pressure increase is performed gently by repeatedly switching the electromagnetic control valve 40 between the pressure increase state and the holding state, but at the start of the pressure increase, the holding time is made shorter than the preset time, As shown by the solid line in FIG. 8 (c), the pressure increase gradient is made steep, and the rise of pressure increase is improved. In the figure, the increase of the brake cylinder pressure is shown by one straight line, but the switching between the pressure increasing state and the holding state is repeated, and the brake cylinder pressure is actually increased stepwise. To be The calculation of the pressure increase time in S13 is the calculation of the rapid pressure increase time due to the shortening of the holding time at the start of the pressure increase, and the rapid pressure increase time is the pressure reduction time represented by the count value C of the counter 92 (hereinafter, C Is expressed). The sudden pressure increase time becomes longer as the pressure decrease time C becomes longer.

After the calculation of the rapid pressure increase time, S14 is executed,
It is determined whether the depressurization time C is equal to or longer than the set time C _A. If the depressurization is performed for the set time C _A or more, S1
The determination result of 4 is YES, and in S15, it is determined whether or not the traveling speed of the vehicle is equal to or less than the set value (15 km / h in this embodiment). If it is less than the set value, S
The determination result of 15 is YES, and in S16, S13
A constant value α is added to the rapid pressure increase time calculated in step S3 to obtain the rapid pressure increase time during low speed traveling.
2 is cleared.

If the depressurization is performed for a time shorter than the set time C _A, the determination result of S14 is NO, and if the traveling speed is greater than the set value even after the depressurization is performed for the set time C _A or more, S15. The determination result of is NO, and S16,
S17 is not executed. Therefore, if either S14 or S15 is NO, the pressure increase command signal and the rapid pressure increase time obtained in S13 are output in S18, whereby the electromagnetic control valve 40 is switched to the pressure increase state and At the start of pressure, the brake cylinder pressure is increased as shown by the solid line in FIG. Also, S14, S
If all the determination results of 15 are YES and the rapid pressure increase time during low speed traveling is obtained in S16, S18 is executed.
In step S16, the pressure increase command signal and the rapid pressure increase time during low speed traveling obtained in step S16 are output, whereby the electromagnetic control valve 40 is switched to the pressure increase state. Figure 8 (c)
The brake cylinder pressure is increased as indicated by the chain double-dashed line.

As described above, the reason why the rapid pressure increase time at the start of pressure increase is lengthened by the constant value α when the traveling speed of the vehicle is less than the set value is that the pulse from the rotation sensor 82 is generated when the traveling speed is low. This is because the cycle of the signal is long and the detection of the wheel speed may be delayed, so that the brake cylinder pressure may be excessively reduced. The average delay T of this detection time can be calculated by the following equation. T = ΔT / 2 + wheel speed calculation cycle / 2, where ΔT: time interval when the pulse of the rotation sensor 82 falls when the speed is Akm / h

The wheel speed is calculated on the basis of the falling edge of the pulse signal, and the wheel speed is calculated at timings a, c, and f during the calculation timings a to f shown in FIG. While the wheel speed changes every moment during the fall, the wheel speed obtained by the calculation is the average value of the wheel speed between successive falls,
And, it is good to think that the wheel speed at the time of half of the trailing edge time interval of the pulse signal is the average speed.
There will be a delay of ΔT / 2 with respect to the latest fall. Further, a minimum 0 and a maximum calculation cycle are deviated between the trailing edge of the pulse signal and the calculation timing, and it can be considered that the delay based on the calculation cycle is equal to half the calculation cycle on average. The calculation delay of may occur at the time when these are combined. For example, if the rotor is provided with 48 teeth, the pulse generation interval is 13 ms at a speed of 10 km / h, and if the calculation cycle of the wheel speed is 5 ms, the average is 9 ms (minimum 6.5 ms, maximum 11.
5 ms) delay occurs.

In the calculation timings shown in FIG. 6, at timings b, d, and e, there is no trailing edge of the pulse signal from the previous calculation timing. In this case, the wheel speed is the previously calculated wheel speed. And estimated based on the vehicle body acceleration when the wheel speed is obtained.

If there is a delay in the detection of the wheel speed, the pressure is excessively reduced. If a delay occurs in the detection of the wheel speed and there is a delay of Δt time in ending the pressure increase as shown in FIG. 7 (a), the brake cylinder pressure increases by the delay. Further, as shown in FIG. 7B, when there is a delay of Δt time in ending the pressure reduction, the pressure reduction is additionally performed by the delay. The pressure increase end delay and the pressure decrease end delay occur with the same probability, but since the pressure decrease is performed by the sudden pressure decrease and the pressure increase is performed by the slow pressure increase, the pressure decrease is larger and the brake cylinder pressure is excessively decreased. .

Further, when there is a delay in the termination of the pressure increase, the slip progresses even if the brake cylinder pressure is not too large, so that the large slip is reduced as shown in FIG. 7 (c). A large amount of decompression
This also leads to excessive reduced pressure. Even if there is a delay in the termination of pressure increase, the brake cylinder pressure increases slightly due to the slow pressure increase, but the pressure is excessively reduced due to the large pressure reduction. These FIG. 7 (a), (b),
The phenomena shown in (c) occur in whole or in part, and the brake cylinder pressure is excessively reduced.

When the traveling speed is low as described above, the brake cylinder pressure may be excessively reduced due to the detection delay of the wheel speed. However, even if the detection delay of the wheel speed occurs, the friction coefficient of the road surface increases. For example, the wheel speed may be recovered quickly and the decompression may be completed early, or the decompression may not be excessively performed due to a relatively small delay in detecting the wheel speed. In such a case, if the time for which the brake cylinder pressure is rapidly increased is lengthened, the wheel speed and the wheel acceleration rapidly decrease and the slip increases as shown by the chain double-dashed line in FIG. In the example, the decompression time is measured, and whether the decompression time actually exceeds the set value is determined by whether or not the decompression time exceeds the set value. Since the determination result in S14 is NO, the rapid pressure increase time is not lengthened, so that the brake cylinder pressure is excessively increased and the slip is prevented from proceeding.

As described above, in the present embodiment, the wheel speed is detected by the pulse type rotation sensor 82, the detection of the wheel speed is delayed during low speed running, and there is a tendency that the pressure is excessively reduced. However, when the pressure is increased thereafter, the brake cylinder pressure is increased steeply so that the braking force is not insufficient and the vehicle can be stopped without extending the braking distance.

As is apparent from the above description, in the present embodiment, the rotation speed sensor 82, the area for storing S1 in the ROM, and the portion for executing S1 in the CPU constitute the wheel speed acquisition means 4, and the vehicle also travels. It constitutes the speed acquisition means 5. In addition, ROM S2 to S8, S10 to S12, S
The area for storing 18 and the portion of the CPU that executes these steps constitute the control means 6, and are S9 and S1 of the ROM.
Area for storing 3 to S17, CPU and RAM
The portion for executing these steps constitutes the pressure increase control means 7 during low speed traveling.

In the above embodiment, α added to the rapid pressure increase time at the start of pressure increase in order to calculate the rapid pressure increase time at low speed traveling is set to a constant value, but when the pressure decrease time is long, α is increased. It is also possible to change α according to the situation.

Further, in the above embodiment, the traveling speed of the vehicle is calculated based on the wheel speed, but it may be acquired by the Doppler type ground speed sensor regardless of the wheel speed. .

Further, since the traveling speed is estimated from the wheel speed and the wheel acceleration, there is an advantage that the longitudinal acceleration sensor is unnecessary and the cost and weight are low. After the anti-skid control is started, the running speed may be estimated based on the running speed and the longitudinal acceleration at the start.

Further, in the above embodiment, when the pressure reducing time is shorter than the set time, the rapid pressure increasing time is not lengthened, and S9 and S14 in the ROM of the computer are set.
Although the area for storing S17 and S17, the CPU and the RAM constitute the excessive pressure increase preventing means, it is not essential to provide such means.

Furthermore, in the above embodiment, the hydraulic pressure control valve device is switched to the pressure increasing state, the holding state and the pressure reducing state, but it may be switched to only the pressure increasing state and the pressure reducing state.

In addition, the present invention can be carried out in various modified and improved modes based on the knowledge of those skilled in the art without departing from the scope of the claims.

[Brief description of drawings]

FIG. 1 is a block diagram conceptually showing the structure of the present invention.

FIG. 2 is a system diagram showing a hydraulic brake device for a four-wheel vehicle equipped with an anti-skid device according to an embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a RAM of a computer which is a main body of a control device of the anti-skid device.

FIG. 4 is a diagram showing a control mode selection map stored in a ROM of the computer.

FIG. 5 is a flowchart showing an anti-skid control routine stored in the ROM.

FIG. 6 is a diagram illustrating occurrence of a wheel speed detection delay.

FIG. 7 is a diagram illustrating excessive reduction of brake cylinder pressure that occurs when a wheel speed detection delay occurs.

FIG. 8 is a graph showing the relationship between time, wheel speed, wheel acceleration, and brake cylinder pressure when the brake cylinder pressure is controlled by the anti-skid device.

FIG. 9 is a diagram illustrating a problem in the case where the pressure increase gradient is made steep when the pressure reduction is not excessively performed in the anti-skid device.

[Explanation of symbols]

10 Master cylinder 16 reservoir 20 left front wheel 22 right front wheel 24 left rear wheel 26 right rear wheel 30, 32 Front brake cylinder 34,36 Rear brake cylinder 40 electromagnetic control valve 50 reservoir 80 controller 82 Rotation sensor

Claims (3)

[Claims] 1. A hydraulic pressure source, a reservoir, and a hydraulic pressure source, the reservoir, and a brake cylinder of a brake device that suppresses rotation of wheels of a vehicle.
At least, a pressure increasing state in which the brake cylinder is communicated with the hydraulic pressure source to increase the hydraulic pressure of the brake cylinder and a pressure reducing state in which the brake cylinder is communicated with the reservoir to reduce the hydraulic pressure of the brake cylinder are switched. Hydraulic control valve device, wheel speed acquisition means for acquiring the speed of the wheel, traveling speed acquisition means for acquiring the traveling speed of the vehicle, and wheels acquired by the wheel speed acquisition means and the traveling speed acquisition means, respectively. In the anti-skid device including the control means for switching the hydraulic pressure control valve device based on the speed and the traveling speed, and controlling the slip of the wheel in an appropriate range, the control means is (1) the liquid of the brake cylinder. A means for controlling pressure increase by rapidly increasing pressure and then gradually increasing pressure; and (2) when the traveling speed is equal to or lower than a set value, By making the travel time longer than when the travel speed exceeds the set value, the low speed travel in which the pressure increase gradient that equalizes the sudden pressure increase and the slow pressure increase is made steeper than when the travel speed exceeds the set value An anti-skid device comprising a temporal pressure increase control means. 2. The low-speed traveling control means sets a pressure increase gradient of the hydraulic pressure of the brake cylinder when the traveling speed is less than or equal to a set value and a previous depressurizing time of the hydraulic pressure of the brake cylinder is set. The anti-skid device according to claim 1, wherein the anti-skid device is used when the time is longer than the time. 3. The anti-skid device according to claim 1, wherein the low-speed running control means includes means for making the pressure increase gradient of the hydraulic pressure of the brake cylinder steeper as the previous depressurization time is longer.