JP2863292B2 - Anti-skid brake system for vehicles - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an anti-skid brake device for a vehicle.

(Prior Art) An anti-skid brake device is basically designed so that a wheel speed is reduced with a predetermined deceleration (control threshold) as a target or a wheel slip ratio is set to a target slip ratio (control threshold). By controlling the increase / decrease of the braking pressure applied to the wheels (hereinafter simply referred to as ABS control as necessary), it is possible to prevent wheel lock or skid from occurring during control, and to maintain directional stability. The vehicle is stopped at a short braking distance without losing the vehicle.

There have been various proposals for the control of the braking pressure.For example, Japanese Patent Publication No. 61-226 discloses that when the behavior of both wheels is different due to a difference in braking efficiency between the left and right wheels, the slip of the wheel on the high-speed rotation side is reduced. A proposal is disclosed in which the pseudo vehicle speed is corrected by the wheel speed on the high-speed rotation side by restricting the control of increasing the braking pressure based on the rate.

(Problems to be Solved by the Invention) By the way, in the ABS control, the ABS control may be started in a state in which one of the left and right drive wheels is generating wheel spin. Is controlled based on the slower wheel speed of the two drive wheels (select low control). Therefore, the brake pressure reduction control is performed up to the drive wheel that is causing wheel spin. As a result, there is a problem that the elimination of the wheel spin is delayed and the vehicle running stability and the braking performance are impaired.

(Means for Solving the Problems) In order to solve such a problem, the present invention regulates the ABS control for the drive wheels that generate wheel spin when the wheel spin state enters the ABS control. is there.

That is, specific means for that purpose include a wheel speed detecting means for detecting the rotation speed of the wheel, a braking pressure adjusting means for adjusting the braking pressure of the wheel, and a predetermined speed based on the wheel speed detected by the wheel speed detecting means. Control means for controlling the braking pressure adjusting means so as to increase and decrease the braking pressure in accordance with the control threshold value.The braking pressure adjusting means is provided separately for the left and right driving wheels, and the control means An anti-skid brake device for a vehicle configured to be able to control the braking pressures of the drive wheels independently of each other, and to determine the presence or absence of wheel spin of each drive wheel based on the wheel speed detected by the wheel speed detection means. A wheel spin determining means for determining, and a controller for determining whether the wheel spin is present for one drive wheel by the wheel spin determining means. Control means for causing the control means to perform the braking pressure control of the left and right driving wheels independently of each other when the braking pressure control is started, and for restricting the braking pressure control for the driving wheels that cause wheel spin. Are provided.

In this case, the pressure reduction control of the braking pressure of the driving wheel on the wheel spin side may be restricted, and the restriction may be released when the wheel spin substantially disappears.
In addition, the above-mentioned regulation means that the braking pressures of the left and right driving wheels are controlled independently of each other.However, when the braking pressures of the left and right driving wheels become the same, the independent control is stopped and integrated control is performed. Can be.

(Operation) In the above-described anti-skid brake system, the ABS control of the drive wheel that causes the wheel spin is restricted, so that the wheel spin can be eliminated early. In this case, the regulation of the pressure reduction control is effective for eliminating the wheel spin, and the regulation may be canceled when the wheel spin has disappeared, and when the braking pressures of the left and right drive wheels become the same. If the control is switched from the independent control to the integrated control, the load on the control system is reduced.

(Effects of the Invention) Therefore, according to the present invention, in an anti-skid brake device for a vehicle, a wheel spin determination unit that determines the presence or absence of a wheel spin of each drive wheel based on a wheel speed, and 1 When braking pressure control by the control means is started in a state where it is determined that there is a wheel spin for one of the drive wheels, the braking pressure control of the left and right drive wheels is made independent of each other, and Since a control regulating means for regulating the braking pressure control is provided, only when the wheel spin is occurring, the braking pressure of the left and right driving wheels is independently controlled so as to eliminate the wheel spin early, thereby improving the vehicle running stability and the braking performance. Can be improved. In addition, if the above regulation is a regulation of pressure reduction control, it is effective to eliminate wheel spin early, and the above regulation is released when wheel spin disappears, and the braking pressure of the left and right drive wheels becomes the same. If the control is switched from the independent control to the integrated control at the time, normal select row control can be performed.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

 FIG. 1 shows the overall configuration of the embodiment.

That is, an anti-skid brake device for a vehicle includes a control means 3 for controlling a control pressure adjusting means 2 to increase or decrease a braking pressure of a wheel based on a wheel speed detected by a wheel speed detecting means 1 in accordance with a predetermined control threshold value; A wheel spin judging means 4 for judging the presence or absence of a wheel spin on the basis of the wheel spin judging means, and a control restricting means 5 for restricting the control by the control means 3 based on the judgment result of the wheel spin judging means 4.

Specifically, as shown in FIG. 2, the vehicle according to this embodiment has left and right front wheels 11, 12 as driven wheels, left and right rear wheels 13, 14 as driving wheels, and Output torque from automatic transmission 16 to propeller shaft 17, differential device 18
The transmission is transmitted to left and right rear wheels 13 and 14 via left and right drive wheels 19 and 20.

Each of the wheels 11 to 14 has a brake device including disks 21 a to 24 a that rotate integrally with the wheels and calipers 21 b to 24 b that brake the rotation of the disks 21 a to 24 a by receiving a supply of braking pressure. 21 to 24 are provided.

A brake control system for operating the brake devices 21 to 24 includes a booster 27 that increases the depression force of a brake pedal 26 by a driver, and a braking pressure according to the force increased by the booster 27. And a master cylinder 28 for generating. The brake pressure supply line 29 for the front wheels extending from the master cylinder 28 branches into a brake pressure supply line 29a for the left front wheel and a brake pressure supply line 29b for the right front wheel, and the calipers 21a and 22b of the brake devices 21 and 22 respectively. It is connected. The left front wheel braking pressure supply line 29a is provided with a first valve unit 30 including an electromagnetic on-off valve 30a and an electromagnetic relief valve 30b.
b is provided with a second valve unit 31 including an electromagnetic on-off valve 31a and an electromagnetic relief valve 31b.

The rear wheel braking pressure supply line 32 extending from the master cylinder 28 branches into a left rear wheel braking pressure supply line 32a and a right rear wheel braking pressure supply line 32b. It is connected to calipers 23a and 24b. The left rear wheel braking pressure supply line 32a is provided with a third valve unit 33 including an electromagnetic on-off valve 33a and an electromagnetic relief valve 33b. A fourth valve unit 36 including an on-off valve 36a and an electromagnetic relief valve 36b is provided.

That is, in the present embodiment, the first channel for adjusting the braking pressure of the brake device 21 of the left front wheel 11 by the operation of the first valve unit 30 and the brake device 22 of the right front wheel 12 by the operation of the second valve unit 31 A third channel for adjusting the braking pressure of the brake device 23 of the left rear wheel 13 by the operation of the third valve unit 33, and a right rear channel by the operation of the fourth valve unit 36. A fourth channel for adjusting the braking pressure of the brake device 24 of the wheel 14 is provided. These channels can be controlled independently of each other, and the third and fourth channels are basically integrated. And control it. The first to fourth valve units 30, 31, 33, and 36 constitute the braking pressure adjusting means 3.

The control unit 34 for controlling the first to fourth channels includes a brake signal from a brake sensor 35 for detecting whether or not the brake pedal 26 is depressed and a stepping speed of the brake pedal 26, and for each of the wheels 11 to 14. Wheel speed sensors 37 to 37 as wheel speed detecting means 1 for detecting the rotational speed of the vehicle.
A wheel speed signal from 40 is input, and ABS control is performed in parallel for each channel.

That is, the control unit 34
Control means 3 for controlling the increase / decrease of the braking pressure of each of the wheels 11 to 14 by the valve units 30, 31, 33, 36 in accordance with a predetermined control threshold value based on the wheel speeds of the wheels 14 to 14; Regulating means 5 for opening and closing the on-off valves 30a, 31a, 33a, 36a and the relief valves 30b, 31b, 33b, 36b of the first to fourth valve units 30, 31, 33, 36 by duty control. Control.

The brake oil discharged from the relief valves 30b, 31b, 33b, 36b is returned to the reservoir tank 28a of the master cylinder 28 by a drain line (not shown).

Hereinafter, the control unit 34 will be specifically described.

The control means 3 includes a pseudo vehicle speed setting unit and a control threshold setting unit. Phase 0 (ABS non-control state) and phase I (A
Select a phase from the braking pressure reduction state during BS control), phase II (holding state after pressure reduction), phase III (rapid pressure increase state after pressure reduction holding), and phase IV (slow pressure increase state after sudden pressure increase). The brake pressure control signal corresponding to each phase is output to the first to fourth valve units 30, 31, 33, and 36.

The pseudo vehicle speed Vr is set as a vehicle speed for convenience based on the wheel speed, since the vehicle speed when the wheels 11 to 14 are slipping cannot be accurately detected. While the maximum wheel speed of the four wheels 11 to 14 is set to the pseudo vehicle speed Vr, the speed change amount is changed from 1.2 G · Δt at the high friction coefficient to 0.3 G · Δt at the low friction coefficient according to the road surface friction coefficient. The correction is made as follows by setting up to Note that Δt is a sampling period (for example, 7 ms) of the control unit 34.

Vr ← Vr− (1.2 G · Δt to 0.3 G · Δt) Further, the pseudo vehicle speed setting unit receives a later-described command from the control restricting means 5 when one of the drive wheels undergoes wheel spin. In this case, the pseudo vehicle body speed Vr is set for the other three wheels except for the driving wheel that causes wheel spin.

The control threshold value is set independently for each channel. In the case of this example, the control threshold value is a threshold value for determining the shift from the phase 0 (when ABS is not controlled) to the phase I (decompression). One wheel deceleration threshold G1 and second wheel deceleration threshold for determining transition from phase I to phase II (hold)
G2, a first slip ratio threshold value S1 for determining a transition from phase II to phase III (sudden pressure increase), and a wheel acceleration threshold value G3 for determining a transition from phase III to phase IV (slow pressure increase)
And a second slip ratio threshold S2 for determining transition from phase IV to phase I. The above control threshold is the pseudo vehicle speed.
It is set appropriately according to Vr and the friction coefficient of the road surface.

Regarding the wheel speeds of the rear wheels 13, 14, in the case of the integrated control, the smaller one of the two wheel speeds is selected as the rear wheel speed. The slip ratio is calculated according to the following equation.

Slip ratio = (1−wheel speed ÷ pseudo vehicle speed) × 100 In this case, the setting of the control threshold value in the normal ABS control is performed by setting the lateral drag coefficient μL of the wheel to the road surface excessively as shown in FIG. It is set so that the coefficient of friction μ between the road surface and the wheels can be increased without lowering, that is, the characteristics in the range of Ss can be obtained. That is,
A high friction coefficient μ means a high braking efficiency, and a high lateral drag coefficient μL means good stability or steering performance in cornering. As shown in FIG. 3, the compatibility is difficult to achieve, and in the normal ABS control, the control threshold is set so that the two are compatible as much as possible.

The deceleration and acceleration of the wheel are obtained by dividing the difference between the previous value and the current value of the wheel speed by the sampling period Δt, and converting the result to a gravitational acceleration.

When detecting the friction coefficient of the road surface, when the ABS is not controlled, it is determined uniformly as a high friction road surface, and after entering the ABS control, the friction coefficient of the road surface is detected based on the wheel deceleration and the wheel acceleration It is. That is, when the wheel deceleration is large and the wheel acceleration is small, it is determined that the road surface is low friction. When the wheel deceleration is small and the wheel acceleration is large, it is determined that the road surface is high friction.

Therefore, the control means 3 normally controls the increase or decrease of the braking pressure as shown in FIG.

That is, when the brake pedal 26 is depressed from the constant speed running state, the braking pressure generated in the master cylinder 28 increases, and the wheel speed decreases accordingly.

When the wheel deceleration becomes larger than the first wheel deceleration threshold value G1, the process proceeds to the ABS control, phase I is selected, and the braking pressure is reduced according to a predetermined pressure reduction mode.

When the wheel deceleration becomes smaller than the second wheel deceleration threshold value G2, phase II is selected and the braking pressure is maintained in a reduced pressure state.

When the slip ratio decreases along with the above-described pressure reduction and exceeds the first slip ratio threshold value S1, phase III is selected, and the braking pressure is rapidly increased.

When the wheel acceleration decreases due to the rapid pressure increase and becomes equal to or less than the wheel acceleration threshold value G3, the phase IV is selected, and the braking pressure is gradually increased.

Due to the above-described slow pressure increase, the slip ratio becomes the second slip ratio threshold value.
Beyond S2, phase I is selected.

As described above, the brake pressure is increased or decreased independently of each other for the first channel, the second channel, and the third and fourth channels. The vehicle will stop at a short braking distance without losing directional stability.

 Next, regulation of the ABS control will be described.

First, the wheel spin judging means 4 includes the wheel speed sensor 3
Based on the wheel speeds of the drive wheels (rear wheels) 13 and 14 detected by the drive wheels 9 and 40, the presence or absence of wheel spin of the drive wheels 13 and 14 is determined. That is, when the wheel speed V obtained by the wheel speed sensor is higher than the pseudo vehicle speed Vr (or higher than Vr by a predetermined value or more), the wheel spin is determined.

The control restricting unit 5 includes a control start mode determining unit that determines whether the ABS control has been started in a state where the wheel spin determining unit 4 determines that one of the driving wheels has the wheel spin. When the ABS control in this mode is started, a command is issued to the pseudo vehicle speed setting unit of the control means 3 to set the pseudo vehicle speed for the other three wheels except for the driving wheel that is causing wheel spin, A command is issued to the control means 3 to control the third channel and the fourth channel independently.

In this case, the control restricting unit 5 causes the pseudo vehicle speed setting unit to continue setting the pseudo vehicle speed on the three wheels until it is determined that there is no wheel spin. With respect to the driving wheels, a restriction command is issued so as not to perform the pressure reduction control until it is determined that there is no wheel spin. In other words, the start time of the ABS control is when the wheel deceleration becomes larger than the first wheel deceleration threshold value G1, but at this time, the braking pressure is not reduced for the driving wheel that is causing wheel spin, It is kept at the braking pressure at the start of the ABS control.

Further, the control restricting means 5 controls the control means 3 for the driving wheels 13 and 14 when the braking pressures of the left and right driving wheels 13 and 14 become the same after the restriction is released. A command is issued to switch from independent control to integrated control.

FIG. 5 is a flow chart of the above-described ABS control regulation control, in which a brake signal and each wheel speed signal are input, and it is first checked whether or not an ABS control start flag is set (F = 1) (step S1, S2). That is, if the flag is not set, it is determined whether or not the ABS control is started, and the flag is set (steps S3 and S4).

Then, from the state where the wheel spin is determined for one of the driving wheels by the wheel spin determination unit 4,
When the above-mentioned ABS control is started, the pseudo vehicle body speed Vr does not include the other three wheels except for the driving wheel causing the wheel spin.
The setting is performed by the wheels, and the left and right driving wheels 13 and 14 are controlled as independent controls to regulate the pressure reduction control for the driving wheels that cause wheel spin (steps S5 to S5).
8).

Thus, when the wheel speed Vs of the drive wheel that has caused the wheel spin becomes less than or equal to the pseudo vehicle speed Vr of the three wheels as a result of the regulation of the pressure reduction control, the setting of the three pseudo vehicle speeds by the four wheels is performed. The setting is switched to release the restriction (steps S9 to S11). And for a while after that, drive wheels 13, 14
Independent control is continued, and when the braking pressures of the two drive wheels 13 and 14 become the same, the control is switched from the independent control to the integrated control, and the flag F is set to zero (steps S12 to S1).
Four).

When it is determined in step S5 that the ABS control is not started from the one-wheel spin state, that is, when the normal ABS control is started, the left and right drive wheels 13 and 14 are integrated control (step S5). S13).

Therefore, the pressure reduction control is restricted for the drive wheels that generate wheel spin even when the ABS control is started, so that a high braking pressure is applied to quickly eliminate the wheel spin and achieve vehicle running stability and braking. The pressure can be increased. In addition, since the above regulation is released when the wheel spin has disappeared, it is advantageous in achieving both the braking performance and the directional stability of the vehicle, and furthermore, the braking pressure of the left and right driving wheels 13, 14 is the same. At this point, the control is switched from the independent control to the integrated control, so that the load on the control system is reduced.

In the above-described embodiment, the pressure reduction control is not performed with respect to the control of the ABS for the drive wheel that causes the wheel spin.However, the degree of the pressure reduction may be reduced. May be delayed.

[Brief description of the drawings]

The drawings show an embodiment of the present invention, FIG. 1 is a configuration diagram of a control system of the embodiment, FIG. 2 is an overall configuration diagram of an anti-skid brake device, FIG. 3 is a slip ratio and a friction coefficient, and a lateral drag coefficient. FIG. 4 is a time chart of the normal ABS control, and FIG. 5 is a flow chart showing the regulation control of the ABS control. DESCRIPTION OF SYMBOLS 1 ... Wheel speed detection means 2 ... Braking pressure adjustment means 3 ... Control means 4 ... Wheel spin determination means 5 ... Control restriction means

Claims (4)

(57) [Claims] A wheel speed detecting means for detecting a rotational speed of the wheel; a braking pressure adjusting means for adjusting a braking pressure of the wheel; and a predetermined control threshold value based on the wheel speed detected by the wheel speed detecting means. Control means for controlling the braking pressure adjusting means so as to increase or decrease the braking pressure, wherein the braking pressure adjusting means is provided separately for the left and right driving wheels, and the control means is adapted for braking the left and right driving wheels. An anti-skid brake device for a vehicle configured to be able to control pressures independently of each other, comprising: a wheel spin determination for determining whether or not each drive wheel has a wheel spin based on a wheel speed detected by the wheel speed detection means. And braking pressure control by the control means is started while the wheel spin determination means determines that one drive wheel has wheel spin. Control means for controlling the braking pressure of the left and right driving wheels by the control means independently of each other and for restricting the braking pressure control of the driving wheels causing wheel spin. Anti-skid brake device for vehicles. 2. The anti-skid brake device for a vehicle according to claim 1, wherein the control restricting means restricts the pressure reduction control. 3. The anti-skid brake for a vehicle according to claim 1, wherein the control restriction means releases the restriction on the braking pressure control when the wheel spin determination means determines that there is no wheel spin. apparatus. 4. The control restricting means switches the control of the left and right driving wheels from independent control to integrated control when the braking pressure of each of the left and right driving wheels becomes the same. An anti-skid brake device for a vehicle according to claim 1.