JPH04218457A - Antilock braking device for vehicle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-lock brake system for a vehicle.

0002

2. Description of the Related Art In recent years, some vehicles are equipped with anti-lock braking systems (hereinafter referred to as ABS) that improve braking performance by suppressing wheel slip during vehicle braking. That is, during braking, wheel speed VW and vehicle speed VB (
For example, the wheel slip rate S{= (VB
-VW ) /VB } and controls the braking force applied to the wheels so that the slip ratio falls within a predetermined range (nearly 0.15 to 0.3), thereby attempting to minimize the braking distance. be.

0003

[Problems to be Solved by the Invention] However, in the conventional ABS having such a control method, the braking force is controlled after detecting wheel slip caused by wheel lock. There was a large response delay from the occurrence of the problem to the time of control, and there was still room for improvement.

The present invention was made in view of the above-mentioned conventional problems, and an object of the present invention is to provide an ABS with improved responsiveness.

[0005]

[Means for Solving the Problems] Therefore, as shown in FIG. 1, the anti-lock brake system for a vehicle according to the present invention comprises a torque detecting means for detecting torque generated in an axle shaft of a drive wheel, and a torque detecting means for detecting torque generated in an axle shaft of a driving wheel. and a braking force control means for controlling the braking force so that the torque detected by the axle shaft is maintained at a predetermined value or less close to 0 in the same direction as the direction in which the driving force is transmitted from the axle shaft to the drive wheels. Configured.

[0006]

[Operation] When the drive wheels become locked during braking, the balance of forces is disrupted and a torque is generated on the axle shaft of the drive wheel in the same direction as the torque generated when driving force is transmitted from the axle shaft to the drive wheels. do. Therefore, the torque is detected by the torque detection means and controlled by the braking force control means so that the torque is maintained at a predetermined value close to zero or less, thereby preventing the occurrence of wheel slip with good responsiveness.

[0007]

[Embodiments] Examples of the present invention will be described below with reference to the drawings. In FIG. 2 showing the overall configuration of one embodiment, a torque sensor 3 as a torque detection means is provided on a propeller shaft to detect the torque of an axle shaft 2 of a rear wheel 1, which is a drive wheel of a rear drive vehicle. The torque signal detected by the torque sensor 3 is input to the ABS controller 4. In addition to the torque signal, the ABS controller 4 receives a signal from a brake switch 5 that is turned on by brake operation, front wheel speed sensors 6A and 6B provided to detect the rotational speed of the front wheels 9, and rotation of the rear wheel 1. In order to detect the speed, a vehicle speed signal from a rear wheel speed sensor 6C provided on the propeller shaft is input, and the ABS controller 4 sets the braking force as described later based on each of the signals, and transmits the braking force control signal to the actuator. Output to 7. The actuator 7 supplies the brake hydraulic pressure from the master cylinder 8 to each wheel cylinder 10 of the front wheel 9 and the rear wheel 1 with ABS control hydraulic pressure that has been adjusted to reduce the pressure according to the braking force control signal from the ABS controller 4. control the braking force of

The braking force control by the ABS controller 4 will be explained below in accordance with the flowchart shown in FIG. 3 and with reference to the state diagram shown in FIG. 4. In step 1 (denoted as S in the figure, the same applies below), brake switch 5
Determine whether it is ON or OFF. If it is OFF, this routine ends, but if it is ON, it proceeds to step 2 and checks whether the vehicle speed is approximately 0 based on the vehicle speed signals from the front wheel speed sensors 6A, 6B and the rear wheel speed sensor 6C. Discern.

If the vehicle speed is approximately 0, this routine ends, but if the vehicle speed is not approximately 0, that is, during deceleration due to braking, the routine proceeds to step 3, where the analog signal of the torque sensor 3 is converted into a digital signal. In step 4, the torque T of the axle shaft 2 detected by the torque sensor 3 is compared with a first set value T1. Here, the torque is defined as positive in the direction in which the driving force is transmitted from the axle shaft 2 to the rear wheel 1, which is the driving wheel (in the direction of the arrow in Figure 2), and the set value T1 is set to a predetermined negative value. . That is, during deceleration, driving force is transmitted from the rear wheels 1 to the axle shaft 2 to drive and rotate the engine, so negative torque is generated in the axle shaft 2 (as shown in part A in FIG. 4). When the rear wheel 1 is braked, the driving force is weakened and the absolute value of the negative torque is reduced. Therefore, when it is determined in step 4 that the detected torque is smaller than the set value T1 (the absolute value is larger), it is determined that the braking force is too small, and the process proceeds to step 5 where it is supplied to the wheel cylinder 10 via the actuator 7. The brake hydraulic pressure is increased to increase the braking force.

If it is determined in step 4 that T≧T1, the process proceeds to step 6, where the torque T is compared with a second set value T2. This second set value T2 is set to a positive value close to zero. That is, if the braking force is too large and the rear wheel 1 is locked, the inertial rotational force of the engine is transmitted to the rear wheel 1 via the axle shaft 2, generating a positive torque T (as shown in B in FIG. 4). part) . Therefore, while the positive torque T is not increasing, it is compared with the second set value T2,
When T>T2, the process proceeds to step 7, where the braking oil pressure is reduced to reduce the braking force.

Further, when it is determined in step 6 that T≦T2, the current state is maintained in step 8. If such braking control is performed, the locking state of the rear wheels 1 can be quickly detected while detecting the torque of the axle shaft 2, and the braking force can be controlled, thereby improving responsiveness and braking performance. still,
The braking force control shown in FIG. 3 by the ABS controller 4 corresponds to braking force control means.

0012

[Effects of the Invention] As explained above, according to the present invention, it is possible to control the braking force with good responsiveness by detecting the locked state of the drive wheels while detecting the torque generated in the axle shaft of the drive wheels. , braking performance in ABS can be improved as much as possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention.

FIG. 2 is a plan view showing the configuration of an embodiment of the present invention.

FIG. 3 is a flowchart showing braking control in the embodiment.

FIG. 4 is a diagram showing the relationship between axle shaft generated torque and vehicle speed during braking control.

[Explanation of symbols]

1 Rear wheel (drive wheel) 2 Axle shaft 3 Torque sensor 4 ABS controller 5 Brake switch 6A, 6B Front wheel speed sensor 6C Rear wheel speed sensor 7 Actuator 9 Front wheel 10 Wheel cylinder

Claims (1)

[Claims] 1. An anti-lock brake system for a vehicle that controls braking force to suppress wheel slip, comprising: a torque detection means for detecting torque generated in an axle shaft of a driving wheel; and a braking force control means for controlling the braking force so that the torque is maintained at a predetermined value or less close to 0 in the same direction as the direction in which the driving force is transmitted from the axle shaft to the drive wheels. An anti-lock braking device for vehicles featuring: