JP3238482B2 - Anti-skid brake system for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle anti-skid brake device.

[0002]

2. Description of the Related Art Conventionally, to prevent the occurrence of a so-called skid state in which the wheels are locked when the vehicle is suddenly braked and the slip of the wheels on the road surface becomes excessive and the deceleration or vehicle stability of the vehicle is impaired. As one means, an anti-skid brake device has been proposed in which the braking force on the wheels is controlled to cope with this. As shown in FIG. 4, the basic idea of this anti-skid brake device is that when the wheel approaches a locked state and the slip amount with respect to the road surface becomes a predetermined value or more (that is, the difference between the vehicle speed and the wheel speed becomes a predetermined value). In this case, the vehicle is decelerated by periodically performing an operation of reducing the brake hydraulic pressure of the hydraulic brake provided on the wheel to reduce the braking force.

On the other hand, in the case of such a brake control, on a normal road where the friction coefficients of the road surfaces on the left and right wheels are substantially equal, the left and right hydraulic brakes operate in the same manner, so that the vehicle becomes unstable. Although it rarely occurs, on a so-called split road where the friction coefficient of the road surface of each of the left and right wheels is greatly different, the slip of the wheels tends to occur on the low friction coefficient (hereinafter referred to as low μ) side. Is started and the braking force is reduced by the operation of reducing the brake oil pressure.
On the other hand, since the wheel slip is small, the brake control is not performed and a relatively high braking force is maintained, and as a result, the tendency of the vehicle to rotate around the wheel on the high μ side becomes stronger.

[0004] As a method for preventing the occurrence of spin during such brake control, for example, Japanese Patent Laid-Open No. 2-254 is disclosed.
Japanese Unexamined Patent Publication No. 051 discloses that when it is determined that the road is a split road, apart from the brake control that periodically repeats the normal pressure reduction and pressure increase, the brake hydraulic pressure on the side corresponding to the high μ road surface is reduced and the brake pressure is reduced. Techniques have been proposed for suppressing the generation of spin by reducing the force.

[0005]

However, spin occurs on a split road having a difference in μ value on the road surface on both the left and right wheels as described above, but the degree of occurrence is not uniform, for example, vehicle speed or the like. Since it varies depending on the degree of the split road (i.e., the pressure difference between the brake oil pressure of the left and right wheels), the brake oil pressure on the high μ side is uniformly reduced when it is determined that the road is a split road as in the above-mentioned known example. In the method, there is a limitation in suppressing the spin.

Accordingly, the present invention has been made to provide an anti-skid brake device for a vehicle that can more reliably prevent the occurrence of spin on a split road and ensure the directional stability of the vehicle.

[0007]

According to the present invention, as specific means for solving the above-mentioned problems, in the invention according to claim 1, wheel speed detecting means for detecting rotation speeds of right and left wheels, respectively, , A hydraulic pressure adjusting means for adjusting the braking force by increasing or decreasing the brake hydraulic pressure in each of the brake means, and a brake hydraulic pressure cycle based on each wheel speed detected by the wheel speed detecting means. The anti-skid brake device for a vehicle, comprising: a control unit that operates the hydraulic pressure adjusting unit so as to increase and decrease the pressure, and a split road determination unit that determines a split road based on brake hydraulic pressures of the left and right wheels. When the split road determination unit determines that the road is a split road, the brake unit corresponding to the wheel on the high μ road surface side shakes. Together to decompress the key hydraulic, the high-μ side pressure reduction amount, while set to the difference between the vehicle speed is high nearly as且 one lateral pressure reduction amount of the wheel side brake hydraulic pressure is increased larger, the pressure reduction control of the first Above high μ decompression
Increase the initial value of the amount and decompress the high μ side after the first time
The amount is set to be smaller than the initial value .

[0008] In the invention 請 Motomeko 2 wherein, in the anti-skid braking system for a vehicle according to claim 1, the high-μ side brake hydraulic pressure of the pressure reduction control when it is determined that the split road, the turning operation of the vehicle The feature is to prohibit this.

[0009]

In each invention of the present application, the following effects can be obtained by adopting such a configuration.

According to the first aspect of the present invention, when it is determined that the road is a split road, and the brake oil pressure on the high μ road surface side is reduced to suppress the occurrence of spin, the higher μ μ side pressure reduction amount is set as the vehicle speed increases. In addition, since the larger the difference between the pressure reduction amounts of the brake hydraulic pressures on the left and right wheels, that is, the higher the probability of occurrence of spin, the larger the difference, the higher the spin suppression effect corresponding to the current running state of the vehicle is expected. You can do it . In addition to this , the high μ-side pressure reduction amount in the split road is increased by increasing the initial value of the pressure reduction control, and thereafter the pressure is reduced by a value smaller than the initial value. In a certain initial pressure reduction control, the braking force on the high μ side is quickly reduced to the required braking force, and an efficient spin suppression action is achieved.

[0011] 2 in the second aspect of the invention, in addition to the action of the one described is obtained, at the time of turning of the vehicle μ value of the road surface for ground load of each wheel is variously changed compared to the straight running It is difficult to control the brakes in response to
In such a case, by stopping the pressure reduction control of the brake hydraulic pressure of the high- [mu] side wheel accompanying the split road determination, erroneous spin suppression control based on the erroneous determination of the split road is prevented beforehand.

[0012]

Therefore, according to the anti-skid brake device for a vehicle according to the present invention, the following effects can be obtained.

(A) According to the anti-skid brake device of the first aspect of the invention, the difference between the vehicle speed and the pressure reduction amount of the brake hydraulic pressure on both the left and right wheels (ie, the degree of the split road).
By setting the high μ-side decompression amount according to the above, the spin control corresponding to the actual vehicle condition becomes possible, and the directional stability of the vehicle on the split road is further enhanced . Further, by executing the effective depressurization at the first time of the depressurization control, the effective spin suppression effect is started from an earlier stage, and the spin suppression effect is further enhanced accordingly.

[0014] (b) According to the antiskid brake apparatus for a vehicle according to claim 2, in addition to the effect of (i), wherein in the difficult conditions precise split road determination of high μ side wheel brake By not performing the spin suppression control by reducing the hydraulic pressure, the effect of increasing the reliability of the brake control can be obtained.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an anti-skid brake device for a vehicle according to an embodiment of the present invention. In the figure, reference numeral 1FL denotes a left front wheel, 1FR denotes a right front wheel, 1RL denotes a left rear wheel, and 1RR denotes a right rear wheel. The engine 2 is mounted horizontally on the front of the vehicle body. The torque generated by the engine 2 is transmitted to the clutch 3, the transmission 4, and the differential gear 5, and then transmitted to the left front wheel 1FL via the left drive shaft 6L. To the right front wheel 1FR via the right drive shaft 6R. As described above, the vehicle in the present embodiment has the front wheel 1F.
L, 1FR is a drive wheel, and the rear wheels 1RL, 1RR are front wheel drive vehicles with driven wheels. In FIG. 1,
Symbols S1 to S4 are wheel speed sensors attached to each wheel, and the wheel speed sensors detect the wheel speed of each wheel.

[0016] Brakes 7FR to 7R mounted on each wheel
R is a hydraulic disc brake. Also,
The master cylinder 8 as a brake hydraulic pressure generating source is a tandem type having two discharge ports 8a and 8b. A brake pipe 13 extending from one discharge port 8a of the master cylinder 8 is branched into two on the way, and one of the branch pipes 13F is connected to the left front wheel brake 7FL (a wheel cylinder mounted in the caliber of the left front brake 7FL). The other branch pipe 13R is connected to the right rear wheel brake 7RR. Also, the other discharge port 8b of the master cylinder 8
Is also branched into two from the middle, one branch pipe 14F is connected to the right front wheel brake 7FR, and the other branch pipe 14R is connected to the left rear wheel brake 7RL. .

Branch pipe 13 for front wheels, that is, for drive wheels
F and 14F are provided with an electromagnetic hydraulic adjustment valve 15L or 1L.
5R is connected, and an electromagnetic on-off valve 16L or 16R is connected to the branch pipes 13R and 14R for the rear wheels. The hydraulic adjustment valves 15L and 15R are connected to the brake 7F.
Switching between the supply of the brake oil pressure from the master cylinder 8 to the L and 7FR and the release of the brake oil pressure of the brakes 7FL and 7FR to the reservoir tanks 22L and 22R via the pipes 21L and 21R is switched. The brake fluid in the reservoir tank 22L is returned to the pipe 13 by a pump 23L via a pipe 25L to which a check valve 24L is connected. Similarly, the brake fluid in the reservoir tank 22R is returned to the pump 23L.
By R, it is returned to the pipe 14 via the pipe 25R to which the check valve 24R is connected.

The stepping force on the brake pedal 12 is
The power is transmitted to the master cylinder 8 via a booster, that is, a brake booster 11. The booster 11 has a case 31 fixed to the vehicle body and the master cylinder 8,
The inside of the case 31 is divided into a first chamber 34 and a second chamber 3 by a diaphragm 32 and a valve body 33 fixed thereto.
5 and so on. The first chamber 34 is always supplied with a negative pressure (for example, the negative pressure of the intake air of the engine 2). When the brake pedal is not depressed, the second chamber 35 is communicated with the first chamber 34 and the booster 11 Is stopped. Then, when the brake pedal 12 is depressed, the atmospheric pressure is supplied to the second chamber 35, whereby the diaphragm 32 is displaced forward together with the valve body 33, and a boosting action is performed.

Anti-skid brake control (hereinafter referred to as ABS control) is performed using such a brake device. The ABS control is a control for preventing the wheels from being excessively slipped on the road surface during braking of the vehicle and the wheels being locked so that the braking performance is reduced and the directional stability of the vehicle is impaired. As shown in FIG. 3, when the slip of the wheel becomes equal to or more than a predetermined value at the time of braking (that is, when the difference between the vehicle body speed and the wheel speed becomes equal to or more than a predetermined value), the brake hydraulic pressure is once reduced to weaken the braking force, and This is to periodically and repeatedly perform hydraulic control such as preventing the lock and increasing the brake oil pressure again by increasing the brake oil pressure with the recovery of the wheel speed,
Since the control itself is publicly known, the description is omitted here.

The determination as to whether or not the traveling road surface is a split road is made based on the amount of pressure reduction of the brake hydraulic pressure on both the left and right wheels. The side having the larger amount is determined to be a low μ road surface), but this determination control is also known, and a description thereof will be omitted.

Therefore, the brake control for suppressing the spin after the road surface is determined to be a split road during the ABS control, which is the gist of the present invention, will be described with reference to the flowchart of FIG. It will be described with reference to FIG.

In the flowchart, it is first determined whether or not the ABS control is currently being performed (step S1). If the ABS control is not being performed, no brake control is performed, but the ABS is not performed. If the control is being performed, it is next determined whether or not the vehicle is currently turning (step S2). If the vehicle is turning, the brake control for suppressing the spin is not performed, and the normal brake control is performed. And sets the ABS control flag F to 0 (step S1).
0,11). Even if the vehicle is not turning, but not traveling on the split road, the normal brake control is performed similarly (steps S2, S3, S10, S11).

This is because the ground load of each wheel changes indefinitely during a turn as compared with the normal state (ie, during straight running), and thus under such conditions, the split road determination and the split road determination are performed. This is because accurate control cannot be ensured even if the spin suppression control is performed.

On the other hand, when it is determined that the vehicle is not turning and is currently traveling on the split road (step S2,
In 3), it is determined whether or not the ABS control flag F is 1 in step S4, that is, whether or not the first control has already been executed (in other words, whether or not the control is the second or later control). .

In the case of the first control, the next step S5
It is first determined whether or not the current vehicle speed (V) is higher than the set vehicle speed (Vt). If (V <Vt), the probability of occurrence of spin is considered to be low. of went by high μ side wheel brake fluid pressure of the pressure reduction time (t ₅₎ (step S7) after setting the ABS control flag F to 1 (step S8,9). On the other hand, when the vehicle speed (V) exceeds the set vehicle speed (Vt), the spin occurrence probability is higher than in the above case, and the spin occurrence probability increases as the degree of the split road increases (that is, both the left and right wheels). Therefore, the decompression time of the brake oil pressure of the high μ side wheel is appropriately changed and set according to the magnitude of the vehicle speed and the degree of the split road.

That is, in this embodiment, when the difference (Δt) between the pressure reduction times of the brake oil pressures on the left and right wheels exceeds the first set pressure reduction time (t ₁ ), the brake oil pressure Is set to the time (t ₃ ) (step S6,1).
3) The difference (Δt) between the decompression times is the first set decompression time.
(t ₁₎ second set decompression time beyond (t ₂₎ is less than the range
If (t ₁ <Δt <t ₂ ), the pressure reduction time of the brake oil pressure of the high μ-side wheel is set to time (t ₄ ) (step S ₄ ).
7,14), and when the difference (Δt) between the pressure reduction times is within a range (Δt <t ₂ ) smaller than the first set pressure reduction time (t ₂ ), the pressure reduction time of the brake oil pressure of the high μ-side wheel is set to time. (t ₅ ) is set (steps S7, S8).

On the other hand, as a result of the determination in step S4, AB
When the S control flag F = 1 (that is, when the control is performed for the second time or later), the pressure reduction time of the brake oil pressure of the high μ-side wheel is set to time (t ₆ ) (step S12).

The above set pressure reduction times (t ₁ , t ₂ ) are (t ₁
> T ₂ ), and each of the above decompression times
(t _{3 to} t ₆ ) are relatively set so that (t ₃ > t ₄ > t ₅ > t ₆ ). Accordingly, in this embodiment, the high μ in the spin suppression control when it is determined that the road is the split road is used.
The lower the amount of pressure reduction of the brake hydraulic pressure of the side wheels, the higher the vehicle speed, and the higher the degree of the split road, in other words,
The higher the probability of spin generation, the larger the value (time) is set, and the pressure reduction amount at the first time of the control having the largest spin suppression effect is set to be larger than the pressure reduction amount at the second and subsequent times. By adopting this pressure reduction amount setting method, the pressure reduction control of the brake oil pressure on the high μ-side wheel is performed most effectively in accordance with the spin occurrence probability, the spin is reliably prevented, and the directional stability of the vehicle is improved. Is guaranteed.

[Brief description of the drawings]

FIG. 1 is a system diagram of an anti-skid brake device for a vehicle according to an embodiment of the present invention.

FIG. 2 is a control flowchart in the anti-skid brake device of FIG.

FIG. 3 is a characteristic diagram of brake control.

[Explanation of symbols]

1FL and 1FR are front wheels, 1RL and 1RR are rear wheels, 2
Is an engine, 7FR to 7RR are brakes (brake means 52), 8 is a master cylinder, 15R and 15L are hydraulic pressure adjustment valves, and S1 to S4 are wheel speed sensors.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kensuke Hayabuchi 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Inside Mazda Co., Ltd. (72) Chizumi Izumi 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Matsu (56) References JP-A-61-166763 (JP, A) JP-A-2-254051 (JP, A) JP-A-62-129552 (JP, A) JP-A-3-70666 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B60T 8/58

Claims (2)

(57) [Claims] 1. A hydraulic adjusting left and right with each wheel wheel speed detecting means for detecting respective rotational speeds of the brake means provided to each wheel, the braking force by increasing or decreasing the brake hydraulic pressure at each brake means Adjusting means; control means for operating the hydraulic pressure adjusting means so as to periodically increase and decrease the brake hydraulic pressure based on each wheel speed detected by the wheel speed detecting means; split based on the brake hydraulic pressures of the left and right wheels An anti-skid brake device for a vehicle, comprising: a split road determination unit that determines a road; and a brake unit corresponding to a wheel on a high μ road surface side when the split road determination unit determines that the vehicle is on a split road. the brake hydraulic pressure causes the vacuum, the high-μ side pressure reduction amount, the vehicle speed is large nearly as the 且 one left and right wheel side brake hydraulic pressure One to set such that the difference pressure amount is increased larger
On the other hand, the initial value of the high μ side pressure reduction amount in the first pressure reduction control
After the first time, increase the decompression amount on the high μ side
An anti-skid brake device for a vehicle, wherein the anti-skid brake device is configured to have a value smaller than the value . 2. The pressure reduction control of a high μ-side brake oil pressure according to claim 1, wherein the determination is a split road.
An anti-skid brake device for a vehicle, wherein the device is prohibited during a turning operation of the vehicle.