JPH0361154A - Anti-lock control method for vehicle - Google Patents

Abstract

PURPOSE:To shorten the control distance in the case that one of two control systems selects the rear wheel speed thereof as the control object wheel speed by making the other system to perform a brake control of the composite speed of the front wheel speed and the rear wheel speed as the control object wheel speed. CONSTITUTION:In an X arrangement type double system brake device, each wheel speed Vw1-Vw4 is computed by computing circuits 5-8 with the output from each wheel speed sensor 1-4, and the higher speed side of the each rear wheel speed Vw3, Vw4 is selected by a high select circuit 13. The selected wheel speed Vw5 and the each front wheel speed Vw1, Vw2 are respectively given to each low select circuit 9, 10, and the low speed side wheel speed as the first and the second system speed Vs1, Vs2 is given to control logic circuit 11, 12. In this case, a mean value computing circuits 14, 15 for computing the mean value of the front wheel speed and the rear wheel speed which belong to each system are provided, and these computing circuits 14, 15 and the low select circuits 9, 10 are switched for use.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an anti-lock control method for preventing wheel jamming during braking of a vehicle.

(Prior art) Anti-lock control devices for vehicles generally convert wheel speeds detected by wheel speed sensors into electrical signals for the purpose of ensuring vehicle steering performance and running stability and shortening braking distance during braking. Based on this, the brake fluid pressure control mode is determined and the hold pulp and decay valves, which are solenoid valves, are opened and closed, thereby pressurizing the brake fluid pressure.
It is controlled by a microcomputer to maintain or reduce the pressure.

This type of anti-lock control is implemented using a cross piping type (X-shaped)
Vehicles with dual brake systems (generally front wheel drive vehicles)
, that is, the right front wheel and the left rear wheel are connected to the first wheel common to them.
When applied to a vehicle with a two-system brake system that brakes through a hydraulic piping system and brakes the left front wheel and right rear wheel through a second hydraulic piping system common to these, each hydraulic piping system must be Anti-lock control is performed for each via independent control channels (two-channel control). In that case, one of the 4-sensor 2-channel anti-lock control methods in which speed sensors are installed on the 4 wheel metal parts.
There is a control method called the rear wheel select high method.

In other words, the wheel speed on the higher side of the right rear wheel speed and the left rear wheel speed is selected (Select High), and the wheel speed on the lower side of the rear wheel speed selected as High and the right front wheel speed is selected (Select Low). ) is the system speed Vsl for the first hydraulic piping system to which the front right wheel belongs, and the lower wheel speed (select low) of the rear wheel speed selected as high and the front left wheel speed is the system speed Vsl for the first hydraulic piping system to which the front left wheel belongs. The system speed related to the pressure piping system is Vs2, and anti-lock control of each channel is performed using these system speeds VS1 and Vs2 as the wheel speeds to be controlled.

FIG. 3 is a block diagram showing the control system of the select high type X-piping type dual-system brake device.

1 is a right front wheel speed sensor, 2 is a left front wheel speed sensor, 3 is a left rear wheel speed sensor, and 4 is a right rear wheel speed sensor, and these speed sensors 1 to 4 each have a frequency signal f proportional to the rotational speed of the wheel. ~f4 is generated. Each frequency signal f1 to f,
are sent to arithmetic circuits 5 to 8, where they are calculated and signals indicating the respective wheel speeds Vwl to Vw4 are calculated.

First, the left rear wheel speed Vw3 and the right rear wheel speed Vw4 are given to the high select circuit 13, and the high speed side wheel speed is outputted from the high select circuit 13 as Vw5. Then, the wheel speed Vw5 and the right front wheel speed Vwl are given to the 10th select circuit 9, and among them, the wheel speed on the low speed side is given to the control logic circuit 11 as the first system speed Vsl, and the control logic circuit 11 anti-lock control is performed by controlling the hold valve HV and decay valve DV included in the modulator M1 using the first system speed Vsl as the controlled wheel speed. The anti-lock control described above is performed. Further, the wheel speed Vw5 and the left front wheel speed VW2 are given to the 20th selection circuit 10, and the wheel speed on the low speed side is given to the control logic circuit 12 as the second system speed Vs2.
Anti-lock control is performed by controlling the hold valve HV and decay valve DV included in the modulator M2 using the second system speed Vs2 as the controlled wheel speed.

By the way, in the two-channel anti-lock control using the rear wheel select high method as explained above, when both the left and right rear wheels move toward lock, both systems of the two-system brake system reduce the brake fluid pressure. Become. Therefore, although the generated yaw moment is small, there is a drawback that brake fluid pressure for the left and right front wheels is insufficient, making it impossible to secure braking force.

On the other hand, there is a method as disclosed in Japanese Patent Application Laid-open No. 160342/1983. In the above-mentioned publication, in 2-channel anti-lock control using the rear wheel select high method, when both the left and right rear wheels go to lock and one system selects the rear wheel speed of that system as the controlled wheel speed, The own system uses the rear wheel speed as the controlled wheel speed, and the other system uses the front wheel speed of that system as the controlled wheel speed to control the brake fluid pressure.

However, although this method can utilize the braking force more effectively than the method using the configuration shown in Figure 3, it has the disadvantage that the difference in hydraulic pressure between the left and right front wheels becomes large and a large yaw moment is generated. .

(Object of the Invention) Therefore, an object of the present invention is to provide an anti-lock control method that achieves both reduction of yaw moment and shortening of braking distance in two-channel anti-lock control.

(Structure of the Invention) In the present invention, when one of the two control systems selects the rear wheel speed of that system as the controlled wheel speed,
The other system controls the brake fluid pressure by using the composite speed of the front wheel speed and rear wheel speed of that system as the controlled wheel speed.

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

FIG. 1 is a block diagram showing a control system of a four-sensor, two-channel, cross-piping, dual-system brake system applied to the implementation of the present invention. In the configuration shown in FIG. 1, in addition to the configuration shown in FIG. 3, an average value calculation circuit 14 for calculating the average value of the front wheel speed and rear wheel speed belonging to each system
．． 15 and a switch switching logic circuit 16 for switching the switches SWI and SW2. Therefore, except for the circuits 14 to 16 and the switches SWI and SW2, the configuration is the same as that shown in FIG. 3, so common parts will be denoted by the same reference numerals and redundant explanation will be omitted.

The right front wheel speed Vwl and the left rear wheel speed Vw3 are given to the first average value calculation circuit 14, and the average value of both speeds (Vw 1
+Vw 3)/2 is calculated. Similarly, left front wheel speed V
w2 and right rear wheel speed Vw4 are calculated by the second average value calculation circuit 15.
is given, and the average value of both speeds (VW2+VW4)/2 is calculated. The switch switching logic circuit 16 is supplied with the left and right rear wheel speeds Vw3, Vw4 and the outputs Vw6, Vw7 of the first and second low select circuits 9.10.

SWI and SW2 indicate changeover switch functions, and at the start of anti-lock control, these changeover switches SWI and SW2 are
The movable contact is located at the position indicated by the solid line in FIG.

Next, FIG. 2 is a flowchart 1 showing the operation of the switch switching logic circuit 16. First, in step S1, it is determined whether the output Vw6 of the low select circuit 9 is equal to the left rear wheel speed Vw3. That is, it is determined whether the speed that should be the controlled target wheel speed in the first system is the rear wheel speed of the own system. Then, this judgment result is r
If YBsJ, proceed to step S2, switch SWI
is connected to the 10th select circuit 9 side, and the wheel speed Vw
6 as the first system speed Vsl, and the switch SW
2 to the second average value calculation circuit 15 side, Vw9=
Let (Vw2+Vw4)/2 be the second system speed Vs2.

Further, if the determination result in step S1 is "NO", the process proceeds to step S3, and the 20th-select circuit 1
It is determined whether the output Vw7 of 0 corresponds to the right rear wheel speed Vw4. That is, it is determined whether the speed that should be the controlled object wheel speed of the second system is the rear wheel speed of the own system. If the determination result is rYEsJ, the process proceeds to step S4, where the switch SWI is connected to the first average value calculation circuit 14 side, and the wheel speed Vw8=(Vwl +V
W3)/2 is set as the first system speed Vsl, the switch SW2 is connected to the second low select circuit 10 side, and the wheel speed Vw7 is set as the second system speed VS2.

On the other hand, if the determination result in step S3 is "NO", in step S5, the switch SWI is connected to the first low select circuit 9 side, and the switch SW2 is connected to the second low select circuit 10 side.

The above is an explanation of one embodiment of the anti-lock control method according to the present invention. In this embodiment, a two-channel anti-lock control method using the conventional rear wheel select high method is used, and a switch switching logic circuit 16 is added to each of the two systems. If one of the two control systems selects the rear wheel speed belonging to that system as the wheel speed to be controlled, the other system selects the front wheel speed and rear wheel speed belonging to that system. Combined speed with wheel speed (e.g. average speed)
is calculated by an average value calculation circuit, and the brake fluid pressure is controlled using the resultant speed as the wheel speed to be controlled.

In this embodiment, in the first average value calculation circuit 14, the composite speed Vw8 of the right front wheel speed Vwl and the left rear wheel speed Vw3 belonging to the first system is calculated by the formula Vw8-(Vw
Similarly, the second average value calculation circuit 15 calculates the combined speed Vw9 of the left front wheel speed Vw2 and the right rear wheel speed Vw4 belonging to the second system. 2 Vw9=(Vw2+Vw4)/2
It is calculated as the average value given by −
As an example, composite speeds obtained by appropriately weighting the front and rear wheel speeds may be set as Vw8 and Vw9, respectively.

(Effects of the Invention) As is clear from the above explanation, in the present invention, when one of the two control systems selects the rear wheel speed of that system as the wheel speed to be controlled, the other system selects the rear wheel speed of that system as the wheel speed to be controlled. The brake fluid pressure is controlled using the composite speed of the front wheel speed and rear wheel speed as the controlled wheel speed. Therefore, when both the left and right rear wheels move toward lock, the hydraulic pressure of both the left and right front wheels will not be reduced, and the hydraulic pressure difference between the left and right front wheels can also be reduced, reducing the braking distance and reducing the generation of yaw moment. prevention.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the control system of the 4-sensor 2-channel system used to implement the present invention, Fig. 12 is a flowchart of the switch switching logic, and Fig. 3 shows the control system of the conventional 4-sensor 2-channel system. FIG. 1-4-Wheel speed sensor 5-8-Arithmetic circuit 9.10-Low select circuit 11.12-Control logic circuit 13-High select circuit 14.15-Average value arithmetic circuit 16-Switch switching logic circuit

Claims (1)

[Scope of Claims] A cross-piped dual-system braking device in which a first system is a right front wheel brake device and a left rear wheel brake device, and a second system is a left front wheel brake device and a right rear wheel brake device. In preparation, for the first system, the brake fluid pressure is controlled using the speed determined by the select high of the left and right rear wheel speeds and the speed determined by the select low of the right front wheel speed as the controlled wheel speed, and for the second system, the brake fluid pressure is controlled by the speed determined by the select high of the right front wheel speed. In a two-channel anti-lock control method in which the brake fluid pressure is controlled using the speed of the left and right rear wheels selected high and the speed selected low of the left front wheel speed as the controlled wheel speed, one of the above two systems is the system. When the rear wheel speed is selected as the wheel speed to be controlled, the other system controls the brake fluid pressure using the composite speed of the front wheel speed and rear wheel speed of that system as the wheel speed to be controlled. Anti-lock control method for vehicles.