JP2001071887A - Antiskid brake control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To change a pressure releasing start timing for a brake fluid pressure when a vehicle presents a nose dive on a road with a high μ. SOLUTION: This device is provided with a wheel speed calculating mean 91 detecting a wheel rotation speed to calculate a wheel speed, chassis deceleration detecting means 92, 93 detecting a chassis deceleration, a chassis deceleration change calculating mean 94 calculating a change in the chassis deceleration, a nose dive determining mean 95a determining a nose dive of a vehicle during braking, and a brake pressure control mean 96 changing a pressure releasing start condition toward a pressure releasing direction for front wheels. This prevents a driver from feeling a decreased braking force due to an excessive pressure releasing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-skid brake control device for changing a pressure reduction control of a brake hydraulic pressure when it is determined that a vehicle has nose-dive on a high μ road during braking.

[0002]

2. Description of the Related Art Conventionally, as this kind of technology, there is an "anti-skid brake device for a vehicle" disclosed in Japanese Patent Application Laid-Open No. Hei 6-32224. If the friction coefficient (μ value) of the road surface is high and the wheel speed is close to the vehicle speed for more than a set time, the device determines that the road surface state is a high μ road. Under such conditions, in a direction in which the decompression control is more difficult to execute than in other cases, by correcting a threshold that is a criterion for determining whether or not the decompression control is possible,
A reduction in brake pressure due to execution of pressure reduction control is suppressed.

[0003]

In the conventional apparatus, when it is determined that the road is a high μ road, a threshold value (wheel deceleration setting value) serving as a criterion for judging whether or not to perform the pressure reduction control in a direction in which the pressure reduction control is difficult to be executed. ), Pressure reduction control is performed so that the start point of pressure reduction during anti-skid control is delayed.

[0004] Due to the characteristics of the vehicle, when the load shifts from the rear wheel to the front wheel during braking on a high μ road, or when the load on the rear wheel is significantly smaller than that of the front wheel even in a normal state, the high μ A nose dive (a phenomenon in which the vehicle body leans forward) occurs in that the load applied to the front wheels during braking on the road is larger and the load applied to the rear wheels is smaller.

Thus, when braking on a high μ road,
As the brake fluid pressure increases, the braking force increases, and the vehicle deceleration increases, the load on the front wheels increases, and the occurrence of a state in which the wheels tend to lock tends to be delayed.

However, the brake fluid pressure eventually exceeds the road surface reaction force, and the front wheels tend to lock, so that pressure reduction starts. Due to this pressure reduction, the increased braking force is reduced and the load transfer to the front wheels is released, so that the front wheels are more likely to lock.

Further, there is a problem in that the brake fluid pressure is further reduced in order to cancel the locking tendency, so that the driver feels that the braking force is lost due to excessive pressure reduction.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. Even if a nose dive occurs during braking on a high μ road, pressure reduction control is performed on the front wheels before the front wheels enter a locking tendency. An object of the present invention is to provide an anti-skid brake control device that can prevent a driver from feeling that braking force is lost due to excessive pressure reduction.

[0009]

An anti-skid brake control device according to the first aspect of the present invention is an anti-skid brake control device for preventing locking of a wheel that occurs during braking of a vehicle. A wheel speed calculating means for calculating a wheel speed, a vehicle deceleration detecting means for detecting a vehicle deceleration, a vehicle deceleration change amount calculating means for calculating a change amount of the vehicle deceleration, and a nose dive during vehicle braking. An anti-skid brake control device comprising: a nose dive determining means for determining; and a brake pressure control means for changing a pressure reduction start condition in a pressure reducing direction for a front wheel when the nose dive is determined.

An anti-skid brake control device according to a second aspect of the present invention is an anti-skid brake control device for preventing locking of a wheel that occurs during braking of a vehicle.
In an anti-skid brake control device for adjusting a wheel slip generated when a vehicle is braked, a wheel speed calculating means for detecting a rotation speed of each wheel to calculate a wheel speed, and a vehicle deceleration detecting means for detecting a vehicle deceleration Nose dive determining means for determining nose dive during vehicle braking,
Brake pressure control means for reducing the pressure of the front wheels when determining at least one of the occurrence of rear wheel slip and the wheel deceleration based on the wheel speed calculated by the wheel speed calculation means at the time of the nose dive determination. It is provided with.

An anti-skid brake control device according to a third aspect of the present invention is an anti-skid brake control device for preventing a wheel from locking when a vehicle is braked.
Wheel speed calculating means for calculating the wheel speed by detecting the number of rotations of each wheel, vehicle body deceleration detecting means for detecting vehicle body deceleration,
Nose dive determining means for determining a nose dive during vehicle braking, and brake pressure control means for changing a condition for starting pressure reduction of rear wheel brake pressure when the calculated vehicle deceleration is equal to or greater than a predetermined value during the nose dive determination It is provided with.

The nose dive determining means of the anti-skid brake control device according to the present invention determines the nose dive when the variation of the vehicle body deceleration is within a predetermined range and the vehicle body deceleration is larger than a predetermined value. Is what you do.

The nose dive determining means of the anti-skid brake control device according to the fifth aspect of the present invention determines nose dive when the rear wheel slips more than the front wheel based on the wheel speed calculation result.

The nose dive determining means of the anti-skid brake control device according to the invention of claim 6 determines a nose dive when the wheel deceleration continues to be larger than the vehicle body deceleration.

The nose dive judging means of the anti-skid brake control device according to the invention of claim 7 is configured to determine whether the rear wheel is slipping more continuously than the front wheel based on the calculation result of the wheel speed, or the wheel deceleration is continued due to the deceleration of the vehicle body. The nose dive is determined when either one of the values becomes larger and the change amount of the vehicle body deceleration is within a predetermined range.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, the operation of the anti-skid brake control device according to the first embodiment will be described with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing a configuration of an anti-skid brake control device according to the present invention.
As shown in FIG. 1, a right front wheel (FR wheel) 1, a left front wheel (FL wheel) 2, a left rear wheel (RL wheel) 3, and a right rear wheel (RR)
Known wheel speed sensors 5 to 8 are arranged on each of the wheels 4, and a pulse signal is generated in accordance with the rotation of each of the wheels 1 to 4 and input to an electronic control unit (ECU) 9.

Wheel cylinders 11 to 14 are disposed on the wheels 1 to 4, respectively, and brake hydraulic pressure is sent from the hydraulic circuit H to the wheel cylinders 11 to 14 via a hydraulic distribution path. In the hydraulic circuit H, a brake fluid pressure is generated by depressing the brake pedal BP, and the depressed state of the brake pedal BP is detected by the stop switch SS, and a detection signal is transmitted to the ECU 9.

The ECU 9 for inputting the pulse signal and the detection signal is a known microcomputer having a CPU 10, a ROM, a RAM, and an I / O. The ECU 9 controls the brake fluid pressure in the hydraulic circuit H based on the signals. Occurs. This control signal is composed of a pressure increasing signal, a holding signal, and a pressure reducing signal generated for each of the wheels 1 to 4.

FIG. 2 is a block diagram showing means for realizing the function performed by the CPU 10 of the ECU 9 in the anti-skid brake control device according to the first embodiment. In FIG. 2, reference numeral 91 denotes a wheel speed V of each wheel 1-4 based on a pulse signal input from each wheel speed sensor 5-8.
w is a wheel speed detecting means for detecting w, 92 is a vehicle speed calculating means for estimating and calculating a vehicle speed Vv based on each wheel speed Vw,
93 is a vehicle deceleration calculating means for calculating a vehicle deceleration Va during brake control by differentiating the vehicle speed Vv, and 94 is a vehicle body for calculating a change amount of the vehicle deceleration from a difference per unit time of the vehicle deceleration Va. Deceleration change amount calculating means 95a is a nose dive determining means for determining nose dive when the vehicle body deceleration change amount is within a predetermined range; 96 is a nose dive determining means for nose dive determination; When the vehicle deceleration calculated by the deceleration calculating means 93 is larger than a predetermined value, that is, when it is determined that braking is being performed on a high μ road, the pressure reducing start condition is set so that the hydraulic circuit H is easily reduced in pressure. This is a brake control unit to be set.

As conditions for the pressure reduction, for example, the slip condition of the front wheels is eliminated, and only the wheel deceleration is set as a condition.
Alternatively, the slip and wheel deceleration conditions are changed in the direction of pressure reduction. Excessive decompression is prevented by changing the decompression condition and performing the decompression start timing earlier. Vehicle speed calculation means 9
2 and the vehicle body deceleration calculating means 93 represent a vehicle body deceleration detecting means. In addition to the method of calculating the vehicle body deceleration from the wheel speed by calculation, it is also possible to directly detect the vehicle body deceleration using a G sensor.

Next, the operation of the first embodiment will be described with reference to FIGS. The wheel speed detecting means 91 detects the wheel speed Vw of each of the wheels 1 to 4 based on the pulse signals indicating the wheel speed input from the wheel speed sensors 5 to 8. This wheel speed Vw is input to the vehicle speed calculating means 92 and the wheel speed Vw
From w, for example, the vehicle speed (pseudo vehicle speed) Vv is estimated and calculated from the average value of the four wheel speeds. As described above, when the vehicle body speed Vv is calculated, the vehicle body deceleration calculating means 9
3 calculates the vehicle body deceleration Va by differentiating the vehicle body speed Vv.

The vehicle body deceleration change amount calculating means 94 calculates the time T1 during which the deceleration changes from α to β as shown in FIG.
When the time T1 is first longer than the reference time a and smaller than the second reference time b, that is, in a predetermined time range, the brake that promotes the nose dive is suddenly applied. It is determined that the player has stepped strongly. In particular, in a vehicle in which the loads on the front and rear wheels are largely different from each other and the front wheel side is heavier than the rear wheel side, if the brake is suddenly and strongly depressed, the front wheel is heavily loaded, resulting in a nose dive.

However, even in a vehicle with a large load movement, when the panic brake is depressed, the brake pressure on the front wheels increases before the load moves to the front wheels (prior to nose dive), and the vehicle tends to lock. The high μ road braking control is started as usual. In this case, the nose dive determination and the pressure reduction change control are not performed.

FIG. 3B shows that the change time T2 is T1.
It is probable that the brake pedal was depressed gently because it was longer than. Then, since an excessive load is not applied to the front wheels, the pressure reduction of the front wheels can be dealt with at the normal pressure reduction start point (when the front wheels tend to lock), and the early operation of the pressure reduction can be prevented.

If a nose dive is determined here, the brake pressure control section 96 changes the pressure reduction start condition so that the brake pressure on the front wheels can be easily reduced early. That is, as shown in FIG. 4, when the slip amount becomes a small threshold value changed from the conventional threshold value, the pressure reduction of the front wheel brake is started, thereby returning the front wheel speed to the vehicle body speed.

As a result, the decompression start condition is different from the conventional decompression start condition that a slip (difference between the vehicle speed and the front wheel speed) occurs between the vehicle speed and the front wheel speed. Excessiveness is prevented.

Embodiment 2 of Embodiment In the above-described first embodiment, the nose dive is determined when the change amount of the vehicle body deceleration is within the predetermined range. However, when the slip state in which the front wheel speed is higher than the rear wheel speed continues for a predetermined time, the nose dive is determined. Is also good.

FIG. 5 is a block diagram showing a schematic configuration of the anti-skid brake control device according to the second embodiment.
In the drawing, the same reference numerals as those in FIG. 2 indicate the same or corresponding parts. In the figure, reference numeral 95b denotes nose dive determining means for determining the slip of the rear wheel from the difference between the rear wheel speed and the front wheel speed input from the wheel speed detecting means 91, and determining the nose dive when the slip continues. .

That is, when a nose dive occurs on a high μ road, a load is applied to the front wheels and the load is released to the rear wheels, so that the road surface reaction force is high for the front wheels and low for the rear wheels. Therefore, the rear wheels tend to lock more than the front wheels. If this state is determined from the fact that the rear wheel speed is lower than the front wheel speed as shown in FIG. 6, it is determined that there is a nose dive tendency. Is determined.

At the time of a nose dive, since the road surface reaction force of the front wheels becomes large, the front wheels are unlikely to have a locking tendency, and it is difficult to establish conditions for starting pressure reduction for preventing the locking tendency. Conversely, the rear wheels tend to lock because the road surface reaction force is reduced. Therefore, as shown in FIG. 7, if the brake control unit 96 determines that the occurrence of rear wheel slip and the rear wheel deceleration due to the locking tendency that can be determined from the difference between the vehicle speed and the rear wheel speed are constant values, For example, the pressure of the front wheels is started and the front wheel speed is adjusted to the vehicle speed.

Embodiment 3 In the third embodiment, the nose dive is determined by comparing the vehicle body deceleration with the wheel deceleration. FIG. 8 is a block diagram illustrating a schematic configuration of the anti-skid brake control device according to the third embodiment. In the drawings, the same reference numerals as those in FIGS. 1 and 2 indicate the same or corresponding parts.

In the figure, reference numeral 95c denotes a nose dive determining means. At the time of nose dive, the load on the rear wheel moves to the front wheel, so that the road surface reaction force on the rear wheel side becomes small and the vehicle tends to lock. This tendency is remarkably shown by the difference between the wheel speed and the vehicle speed as shown in FIG. Therefore, if the nose dive determining means 95c determines that the wheel deceleration is continuously greater than the vehicle body deceleration for a predetermined time, it determines that a nose dive.

In a nose dive, the rear wheel tends to lock due to a decrease in the road surface reaction force due to the load movement, and when the pressure reducing operation is performed, the pressure reduction becomes excessive as compared with the case of the original anti-skid control. Therefore, at the time of the nose dive determination, the condition is changed so that the start of the decompression becomes difficult as shown in FIG. For example, the rear wheel slip amount, which is the threshold value for the start of pressure reduction, is set large. Alternatively, the amount of reduced pressure may be suppressed at the time of nose dive determination.

Embodiment 4 As shown in FIG. 8, the nose dive determination means determines whether the vehicle body deceleration change amount is within a predetermined range or the rear wheels continuously slip from the front wheels at the wheel speeds of the front and rear wheels. A configuration may be adopted in which a nose dive is determined when detected.
As a result, the nose dive can be accurately determined.

Embodiment 5 FIG. As another embodiment of the nose dive determining means, as shown in FIG. 9, at the wheel speeds of the front and rear wheels, the rear wheels slip more continuously than the front wheels or the wheel deceleration continues more than the vehicle deceleration. May be detected, and when the vehicle body deceleration change amount is within a predetermined range, a nose dive may be determined. As a result, the nose dive can be accurately determined.

[0036]

According to the first aspect of the present invention, in an anti-skid brake control device for preventing locking of a wheel that occurs during braking of a vehicle, a wheel speed calculation for detecting a rotation speed of each wheel and calculating a wheel speed. Means, a vehicle deceleration detecting means for detecting a vehicle deceleration, a vehicle deceleration change amount calculating means for calculating a change amount of the vehicle deceleration, a nose dive determining means for determining a nose dive during vehicle braking, At the time of nose dive determination, the front wheels are provided with the brake pressure control means for changing the decompression start condition in the decompression direction, so that there is an effect that it is possible to prevent the driver from feeling too much decompression due to excessive decompression. .

According to a second aspect of the present invention, there is provided an anti-skid brake control device for preventing wheel lock generated during braking of a vehicle, and an anti-skid brake control device for adjusting wheel slip generated during vehicle braking. Wheel speed calculating means for calculating the wheel speed by detecting the rotation speed of each wheel; vehicle body deceleration detecting means for detecting vehicle deceleration; nose dive determining means for determining nose dive during vehicle braking; A brake pressure control means for reducing the pressure of the front wheels when determining at least one of the occurrence of slip of the rear wheel and the wheel deceleration based on the wheel speed calculated by the wheel speed calculation means at the time of dive determination. Therefore, there is an effect that the pressure reduction control can be easily determined.

According to the third aspect of the present invention, there is provided an anti-skid brake control device for preventing locking of a wheel which occurs during braking of a vehicle, a wheel speed calculating means for detecting a rotation speed of each wheel and calculating a wheel speed. A vehicle deceleration detecting means for detecting a vehicle deceleration, a nose dive determining means for determining a nose dive during braking of the vehicle, and a nose dive determination when the calculated vehicle deceleration is equal to or more than a predetermined value. The provision of the brake pressure control means for changing the condition for starting the reduction of the brake pressure of the wheels is provided, so that it is possible to prevent an excessive reduction in the pressure.

According to the fourth aspect of the present invention, the nose dive determining means determines the nose dive when the variation of the vehicle body deceleration is within a predetermined range and the vehicle body deceleration is larger than a predetermined value. There is an effect that determination of nose dive becomes easy.

According to the fifth aspect of the present invention, the nose dive determining means determines the nose dive when the rear wheel slips more than the front wheel based on the wheel speed calculation result, so that the nose dive can be easily determined. It has the effect of becoming.

According to the sixth aspect of the present invention, the nose dive determining means determines the nose dive when the wheel deceleration continues to be larger than the vehicle body deceleration, thereby facilitating the nose dive determination. effective.

According to the seventh aspect of the present invention, the nose dive determination means determines whether the rear wheel is slipping more continuously than the front wheel based on the wheel speed calculation result or when the wheel deceleration is continuously larger than the vehicle deceleration. By determining the nose dive when any one of the above and the change amount of the vehicle body deceleration is within the predetermined range, the nose dive can be determined more accurately.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating the configuration of an anti-skid brake control device according to the present invention.

FIG. 2 is a block diagram illustrating functions of an ECU in the anti-skid brake control device according to the first embodiment.

FIG. 3 is a diagram for explaining determination of a nose dive in the first embodiment.

FIG. 4 is a diagram illustrating a control operation at the time of nose dive determination according to the first embodiment.

FIG. 5 is a block diagram showing functions of an ECU in the anti-skid brake control device according to the second embodiment.

FIG. 6 is a diagram for explaining determination of a nose dive in the second embodiment.

FIG. 7 is a diagram illustrating a control operation at the time of nose dive determination according to the second embodiment.

FIG. 8 is a block diagram showing functions of an ECU in the anti-skid brake control device according to the third embodiment.

FIG. 9 is a diagram for explaining nose dive determination in the third embodiment.

FIG. 10 is a diagram illustrating a control operation at the time of nose dive determination according to the third embodiment.

FIG. 11 is a block diagram showing functions of an ECU in the anti-skid brake control device according to the fourth embodiment.

FIG. 12 is a block diagram showing functions of an ECU in the anti-skid brake control device according to the fifth embodiment.

[Explanation of symbols]

9A to 9D ECU, 91 wheel speed detecting means, 92 vehicle body speed calculating means, 93 vehicle body deceleration calculating means, 94 vehicle body deceleration change amount calculating means, 95a to 95d no-diagram dive determining means, 96 brake pressure control section, 97, 97a Wheel deceleration calculating means.

Claims (7)

[Claims] An anti-skid brake control device for preventing locking of wheels generated during braking of a vehicle, a wheel speed calculating means for calculating a wheel speed by detecting a rotation speed of each wheel, and detecting a vehicle body deceleration. Vehicle body deceleration detecting means, vehicle body deceleration change amount calculating means for calculating a change amount of the vehicle body deceleration, nose dive determining means for determining a nose dive at the time of vehicle braking, and the front wheel is depressurized in the nose dive determination. An anti-skid brake control device, further comprising: a brake pressure control means for changing a pressure reduction start condition. 2. An anti-skid brake control device for preventing locking of wheels generated during braking of a vehicle, wherein the rotation speed of each wheel is detected in an anti-skid brake control device for adjusting slip of wheels generated during braking of a vehicle. Wheel speed calculating means for calculating the wheel speed, vehicle body deceleration detecting means for detecting vehicle deceleration, nose dive determining means for determining nose dive at the time of vehicle braking, A brake pressure control means for reducing the pressure of the front wheels when it is determined that at least one of the occurrence of slip and the wheel deceleration based on the wheel speed calculated by the wheel speed calculation means has reached a predetermined value. Skid brake control device. 3. An anti-skid brake control device for preventing locking of wheels generated during braking of a vehicle, a wheel speed calculating means for calculating a wheel speed by detecting a rotation speed of each wheel, and detecting a vehicle deceleration. Vehicle body deceleration detection means, nose dive determination means for determining nose dive during vehicle braking, and, when nose dive determination is performed, pressure reduction start conditions for rear wheel brake pressure when the calculated vehicle body deceleration is equal to or greater than a predetermined value. An anti-skid brake control device, comprising: brake pressure control means for changing the brake pressure. 4. The nose dive determining means determines a nose dive when the amount of change in the vehicle body deceleration is within a predetermined range and when the vehicle body deceleration is larger than a predetermined value. 3. The anti-skid brake control device according to any one of 3. 5. The nose dive determination unit according to claim 1, wherein the nose dive determination unit determines a nose dive when the rear wheel slips more continuously than the front wheel based on a wheel speed calculation result. Anti-skid brake control device. 6. The anti-skid device according to claim 1, wherein said nose dive determining means determines a nose dive when the wheel deceleration continuously becomes larger than the vehicle body deceleration. Brake control device. 7. The nose dive determining means determines whether the rear wheel is slipping more continuously than the front wheel based on the wheel speed calculation result, or the wheel deceleration is continuously larger than the vehicle deceleration, and 4. The anti-skid brake control device according to claim 1, wherein a nose dive is determined when a change amount of the vehicle body deceleration is within a predetermined range.