JPH059266Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention is an anti-skid brake device that can ensure stability during control of a four-wheel drive vehicle, especially an anti-skid brake system for a four-wheel drive vehicle that uses two modulators. Regarding brake equipment.

(Prior technology) An anti-skid brake system detects the deceleration and slip rate of rotating wheels when braking a vehicle, and operates a modulator as a brake pressure regulator in the vehicle's brake hydraulic system based on these values to prevent wheel lock. The device is known.

By the way, among the brake piping types for vehicles, the seventh
The front and rear piping shown in Figures a and b and the X shown in Figure 7 c and d
Piping (also called diagonal piping) is often used. Among these, the front and rear piping is equipped with four modulators (1), but in the case of two modulators, anti-skid control is often performed by front wheel select high and rear wheel select low, which improves braking stability. It is possible to suppress the increase in braking distance. However, this front and rear piping has a problem in that if a defect occurs in the front wheel hydraulic system, the braking distance will increase rapidly.

On the other hand, in the case of X piping, whether it is 4 modulators or 2 modulators, if diagonal wheel select high control is used, one rear wheel will be locked, resulting in a lack of braking stability; conversely, if diagonal wheel select low control is used, braking stability will be reduced. This causes an increase in distance. This tendency is particularly noticeable on split roads where the paved road surface has an icy slope with a low friction coefficient on both the left and right sides.

(Problem that the invention aims to solve) However, in a 4-wheel drive vehicle using 2 modulators with X piping, when the 4-wheel drive is connected directly, a rotational effect occurs, and one-wheel lock almost never occurs.
Even if control is performed using diagonal wheel select high (SH), the above-mentioned problem of lack of braking stability will not occur. However, in a non-4WD directly connected state other than this 4WD directly connected state, as mentioned above, there are problems in that braking stability decreases in select high mode and braking distance increases in select low mode.

The purpose of the present invention is to provide a brake system for a four-wheel drive vehicle that is equipped with two hydraulic pipe systems that apply braking force to the front, rear, left and right wheels, and each of both hydraulic pipe systems is equipped with one modulator. An object of the present invention is to provide an anti-skid brake device for a four-wheel drive vehicle that can ensure braking stability and prevent an increase in braking distance.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides arrangement information on whether the arrangement of the power transmission system is a 4WD direct coupling state in which the front and rear wheels are directly coupled or a non-4WD direct coupling state. a power transmission system array sensor that outputs information about the wheel speed of the front, left, and right wheels; and a wheel speed sensor that outputs wheel speed information for the front, left, and right wheels; and when the first piping is used, hydraulic pressure from the master cylinder is applied to the braking cylinder for each of the front and rear wheels via the first modulator. and a second hydraulic pipe system that transmits the hydraulic pressure of the master cylinder to the brake cylinders of each of the front and rear wheels and the left and right opposite wheels when the first piping is used, and the hydraulic pressure of the master cylinder is transmitted via a second modulator. Then, the first and second hydraulic pipe systems in the first piping state are connected to the hydraulic pressure from one of the modulators in the second piping state to the cylinders of the left and right front wheels, and the hydraulic pressure from the other modulator to the left and right cylinders. The first and second hydraulic pipe systems are connected to the 4WD directly connected state by switching the switching valves based on the arrangement information and the wheel speed information, and switching the switching valves to a state in which the transmission is transmitted to the cylinders of the rear wheels, respectively. The control means is configured to switch to the first piping state at times and to the second piping state when in the non-4WD direct connection state, and to perform anti-skid control on the two modulators.

(Function) When the 4-wheel drive vehicle is in the 4-wheel drive direct connection state, the first and second hydraulic pipe systems are switched to the first piping state, anti-skid control is performed by the two modulators, and the 4-wheel drive vehicle is in the non-4 drive state. When in direct connection, the second
Switch the first and second hydraulic pipe systems to the piping state, and
Anti-skid control can be performed using two modulators.

(Embodiment) The anti-skid brake device for a four-wheel drive vehicle (hereinafter simply referred to as a brake device) shown in FIG. The first modulator 12 connects the first hydraulic chamber 101 and the branch 111 of the first hydraulic pipe system 11 and the second hydraulic chamber 102 of the master cylinder 10 and the branch 141 of the second hydraulic pipe system 14 The second modulator 13 that connects
, an electromagnetic switching valve 23 installed across the brake cylinders 19, 20, 21, 22 for the front and rear left and right wheels 15, 16, 17, 18, and the first and second hydraulic pipe systems 11, 14. and an array sensor 26 as a power transmission system array sensor that issues an output signal when the center differential 25 is switched to the differential lock state.
and a controller 24 that drives and controls both the modulators 12 and 13 and the switching valve 23.

Moreover, the controller 24 includes an array sensor 26.
In addition, wheel speed sensors 27, 28, 29, 30 each comprising a signal generator outputting wheel speed information of the front, rear, left and right wheels 15, 16, 17, 18;
A brake sensor 32 that outputs brake information when the brake pedal 31 is actuated and a G sensor 33 that outputs vehicle acceleration/deceleration information are connected.

The switching valve 23 switches between the first and second switching valves when not energized.
The hydraulic piping system is switched to the first piping state and to the second piping state during excitation. That is, in the first piping state, as shown by solid lines in FIG. 1, the cylinder 22 is communicated with the branch part 111 of the first hydraulic pipe system, and the cylinder 20 is communicated with the branch part 141 of the second hydraulic pipe system, respectively.
As a result, an X piping (diagonal piping) as shown in FIG. 2a is achieved. Furthermore, in the second piping state, the cylinder 20 is connected to the branch part 111, and the cylinder 20 is connected to the branch part 14.
1 and the cylinders 22 respectively, and as a result, front and rear piping as shown in FIG. 2b is achieved.

When both modulators 12 and 13 are inactive, the hydraulic pressure in both hydraulic chambers 101 and 102 is directly transmitted to the branch portions 111 and 141 side. On the other hand, during anti-skid operation, the first modulator 12 reduces the hydraulic pressure in both hydraulic chambers 101 and 102 in a timely manner.
Alternatively, anti-skid control is performed to increase the pressure and is transmitted to the branch portions 111 and 141.

The center differential 25 is equipped with a well-known differential limiting device, for example, the one disclosed in the specification and drawings of Japanese Patent Application No. 109449/1983 proposed by the present applicant. The array sensor 26 attached to the center differential may be a switch that turns the center differential 25 on or off and operates in conjunction with a differential switch (not shown).
Alternatively, if the differential lock of the center differential is switched and controlled by a control lever, a switch that is linked to the switching operation of the lever can be used.

Controller 24 is formed using a microcomputer. This controller uses two modulators 12, 13 based on output signals of four wheel speed sensors 27, 28, 29, 30, a brake sensor 30, a G sensor 33, and an array sensor 26.
and controls the switching valve 23. controller 24
FIG. 4 shows the anti-skid control program stored in the read-only memory (ROM) in the machine.

When this program starts, it first clears all flags as preprocessing, checks each sensor and hydraulic system, and activates a warning means (not shown) when a failure is detected.

Next, wait for the brake signal to turn on, and while the brake signal is off, first determine the presence or absence of the N flag, and if the N flag is not set, proceed to step 4a, clear the S flag, switch to the The process of setting a flag is performed. After the N flag is raised, the closed loop of steps 2a and 3a is exited by turning on the brake signal, and the skid detection speed B and each wheel speed sensor 27, 28, 29, which detects the presence or absence of skid wheels, are
Judgment is made based on the code of 30.

Note that each wheel speed C1, C, D1, D2, approximate vehicle speed A, skid detection speed B, etc. (see Figure 3) are repeatedly executed over time at predetermined time interruptions as shown in Figure 5. It is updated sequentially by the wheel speed calculation routine. That is, here, first, each wheel speed C1, C2, D1, D2 is calculated based on the output of each wheel speed sensor 27, 28, 29, 30, and is replaced in each predetermined memory. Then, the maximum value among the four wheel speeds C1, C2, D1, and D2 is selected, an approximate vehicle body speed A is calculated based on that value, and the approximate vehicle speed A is stored in a predetermined memory. Furthermore, the skid detection speed B is calculated by multiplying the approximate vehicle speed A by a coefficient for skid discrimination (for example, 0.9), and the skid detection speed B is stored in a predetermined memory and the process returns to the main routine.

If there is no skid wheel in step 7a of the main routine, the process proceeds to step 3a, and if there is a skid wheel, the process proceeds to step 8a. Here, it is determined based on the output of the array sensor 26 whether or not the differential lock is released, and if the differential lock is activated, the process proceeds to step 9a. Here, in the X pipe, anti-skid control is performed using diagonal wheel select high (SH). That is, one of the front right and rear left wheels 15, 18 that rotates at a higher speed is selected, and based on that wheel speed and the deceleration obtained from the G sensor 33, it is calculated whether or not a skid has occurred. The modulator 12 is operated to reduce the hydraulic pressure, and when the hydraulic pressure is restored, the modulator 12 is operated to return the hydraulic pressure (see symbol P1 in FIG. 3a) to its original level. The front left and rear right wheels 16 and 17 are processed in the same way, and the second
The modulator 13 operates the oil pressure P2 to operate the antiskid, and the process returns to step 2a.

The anti-skid control here is a direct-coupled 4-wheel drive control, and it is assumed that locking of one rear wheel will hardly occur due to the dragging effect, which not only shortens the braking distance but also ensures braking stability. Ru.

On the other hand, when proceeding from step 8a to step 10a, that is, to release the deflock, the presence or absence of the S flag is first determined, and if the S flag is not set, the N flag is cleared and a switching signal is output at switching point 23. Then, from the first piping state (see Figure 2 a), the second
The first and second hydraulic systems 1 are connected to the piping state (Fig. 2b).
Switch between 1 and 14. And set the S flag,
Proceed to step 14a. Note that if the S flag is set at step 10a, the process directly advances to step 14a. Here, first, the front wheel select high (SH) is controlled in the front and rear piping.
Select the one on the high rotation side among wheel speeds C1 and C2,
Based on the wheel speed C(SH) and the deceleration obtained from the G sensor 33, it is calculated whether skid has occurred.
When there is a skid, the first modulator 12 is operated to reduce the hydraulic pressure (see symbol P3 in Fig. 3b), and when the oil pressure recovers, the anti-skid operation is performed to return the oil pressure to the original level.The process proceeds to step 16a, and if there is no skid, Proceed directly to step 16a. Here, the rear wheel select low (SL) is controlled, and one of the wheel speeds D1 and D2 on the low rotation side is selected, and based on that wheel speed D (SL) and the deceleration of the G sensor 33. , calculate whether skid has occurred. When a skid occurs, the second modulator 13 is activated for anti-skid, the hydraulic pressure P4 is adjusted, and the process returns to step 2a.

When there are no skid wheels or the brake signal is turned off, the processes from steps 3a to 6aa are first performed, and then the closed loop of steps 2a and 3a is repeated.

In this way, the brake system shown in FIG.
Keep 1 and 14 in the X piping (first piping).

Furthermore, when braking, skidded wheels occur, and when defrocking, anti-skid control is performed using diagonal wheel select high (SH) while leaving the X piping in place.
During braking, skidded wheels occur, and when the differential is released, both hydraulic piping systems 11 and 14 are switched to front and rear piping, and anti-skid control is performed by selecting low (SL) on the rear wheel side and selecting high (SH) on the front wheel side.

In this way, the brake system shown in Figure 1 maintains the brake hydraulic piping system in the X piping, which is suitable for front-wheel drive vehicles with a relatively large load shared by the front wheels, in the non-4WD direct-coupled state.
Taking advantage of the fact that one rear wheel is almost never locked, anti-skid control is performed using diagonal wheel select high, and when the 4WD is directly connected, the brake hydraulic piping system is kept in the front and rear piping, and the front wheel select high (SH) is applied.
Anti-skid control is performed using the rear wheel select low (SL) to prevent braking distance from increasing in each condition and ensure braking stability.

Although the brake device shown in Figure 1 is intended to be installed on a front-wheel drive vehicle, the brake system of the present invention may alternatively be installed on a rear-wheel drive vehicle (FR vehicle) with a relatively large load shared by the rear wheels. The anti-skid control program executed by the controller 24 in that case is shown in FIG.

When this program starts, it first performs the same preprocessing as described above, then turns off the brake signal and
If the M flag is not set, the R flag is cleared, the front and rear piping is switched, and the M flag is set. When the brake signal is turned on, the process proceeds to step 7b, where it is determined whether or not there is a skid wheel. here,
The determination is made based on the skid detection speed B obtained by executing the wheel speed calculation routine described above (see FIG. 5) and the output signals of the respective wheel speed sensors 27, 28, 29, and 30.

In step 8b, it is determined whether or not to release the deflock, and if it is released, the process proceeds to step 9b. Here, in the front and rear piping, first select the front wheel select high (SH)
The first modulator 12 is operated in order to perform anti-skid control according to the method of the present invention, and when no skid occurs, the process directly proceeds to step 11b. Here, the second modulator 13 is operated to perform anti-skid control using the rear wheel select low (SL), and if no skid is occurring, the process returns directly to step 2b.

On the other hand, if it is determined in step 8b that the defroster is locked, the process proceeds to step 13b. Here, if the R flag is not set, the M flag is cleared and the
The switching valve 23 is operated to switch to the piping, and the R
Set the flag and proceed to step 17b. Note that after the R flag is set in step 13b, the process directly proceeds to step 17b. Here, since it is X piping,
Both modulators 12 and 13 are activated to perform anti-skid control using the diagonal wheel select high, and the process returns to step 2b.

When there are no skid wheels or the brake signal is turned off, the processes from steps 3a to 6a are first performed, and then the closed loop of steps 2a and 3a is repeated.

In a brake system that performs such anti-skid control, when in a non-4WD direct-coupled state, the brake hydraulic piping system is maintained in the front and rear piping suitable for FR vehicles with a relatively large load shared by the rear wheels, and the front wheel select high (SH) and rear Anti-skid control is performed using wheel select low (SL), and when 4WD is directly connected,
By maintaining the X piping and performing anti-skid control using diagonal wheel select high, it is possible to suppress the increase in braking distance and ensure braking stability in each condition.

In the above, each brake device is installed on a vehicle equipped with a center differential, but instead of this, the present invention can be applied to a part-time vehicle, and in that case, the 2WD mode can be changed to the non-4WD mode It will be considered as such. And as the array sensor 26, 2
Similar control will be performed using a lever for switching between WD and 4WD and a switch linked to the switch button.

(Effect of the invention) The brake hydraulic system can be switched to the first piping state or the second piping state depending on whether the 4WD is directly connected or not when the 4WD is directly connected. It suppresses the increase in braking distance and ensures braking stability.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a brake device as an embodiment of the present invention, Fig. 2 a and b are explanatory diagrams of each of the X piping and front and rear piping of the above brake device, and Fig. 3 is the operation of the same brake device. FIGS. 4 and 5 are flowcharts of the control program used in the above braking device. FIG. 6 is a flowchart of the control program used in another embodiment of the present invention.
Figures a, b, c, and d show schematic illustrations of different conventional brake devices, respectively. 10... Master cylinder, 12, 13... Modulator, 11, 14... Hydraulic pipe system, 23... Switching valve, 24... Controller, 26... Array sensor, 27, 28, 29, 30... Cylinder.

Claims (1)

[Scope of utility model registration request] A power transmission system array sensor that outputs array information on whether the power transmission system is in a 4WD direct-coupled state that directly connects the front and rear wheels or in a non-4WD direct-coupled state, and outputs each wheel speed information for the front, left, and right wheels. a first hydraulic pipe system that transmits the hydraulic pressure of the master cylinder to the braking cylinder of each front and rear wheel via a first modulator when the first piping is in place; Apply the hydraulic pressure of the master cylinder to the brake cylinder of each wheel on the opposite side.
a second hydraulic pipe system transmitting via a modulator, the first and second hydraulic pipe systems in the first piping state, and the hydraulic pressure from one of the modulators in the second piping state to the cylinders of the left and right front wheels; A switching valve that can be switched to a state where the hydraulic pressure from the other modulator is transmitted to the cylinders of the left and right rear wheels, respectively, and the switching valve is switched based on the arrangement information and the wheel speed information, Second
A four-wheel drive system having a control means for switching the hydraulic piping system to a first piping state when the 4WD is directly coupled, and to a second piping state when the 4WD is not directly coupled, and controlling the two modulators for anti-skid. Anti-skid brake device for cars.