JPS6171265A - Anti-skid control - Google Patents

Abstract

PURPOSE:To control the braking force of respective wheel while maintaining suitable slip rate by functioning a hydraulic control circuit such that the hydraulic brake pressure of rear left wheel is released simultaneously with start of anti-skid control. CONSTITUTION:Speed sensors 16-19 assembled in respective wheel will detect the rotary speed of wheel and provide to an anti-skid control circuit 20. Said circuit 20 will detect abrupt droppage of wheel speed upon braking to start anti-skid control, here the detection of abrupt droppage of wheel speed is executed by comparing a simulated car speed signal lowering with predetermined rate from the start of braking with an actual wheel speed. A hydraulic control circuit 12 is functioned such that the hydraulic brake preesure of brake system 8 for the rear left wheel 4 is released simultaneously with start of anti-skid control.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of Start] The present invention relates to an anti-skid control method for a four-wheel vehicle.

[Background of the invention]

As is well known, in order to prevent the risk of wheel locking that occurs when a vehicle is braking, various anti-skid control methods and devices have been proposed, including reducing, holding, and repressurizing the brake hydraulic pressure. It's coming.

Here, these methods and devices that have been proposed in the past detect excessive braking force applied to the wheels using the upper limit of wheel deceleration that should occur during braking as a guide, and detect excessive braking force. Generally, the brake force is varied (specifically, the brake oil pressure is varied) in order to eliminate the wheel lock that occurs when the vehicle is locked.

In other words, the braking force (input) that should be applied to the wheels,
Anti-skid control is considered as a control system that corresponds to changes in wheel rotational speed (output) caused by this.

However, the brake control system that includes the wheels of a running vehicle is not immune to environmental conditions, as it is typically affected by the coefficient of friction of the road surface (hereinafter referred to as road surface μ). The ease of locking is significantly different. Therefore, if anti-skid control is performed in the same mode, the control effect will only be obtained under specific conditions, so many proposals have been made to incorporate such environmental parameters into control. There is.

However, the incorporation of these environmental parameters into the control system
It cannot be continuous and immediate, so-called on/o
It is a ff control system.

By the way, the reason why the anti-skid control system for a vehicle is not configured by incorporating the above environmental parameters is that the vehicle that has this control system is a running vehicle, and the ground speed of the vehicle during braking (hereinafter referred to as This can be said to originate from the fact that it is difficult to measure the absolute vehicle speed (absolute vehicle speed).If the absolute vehicle speed could be measured, it would be possible to calculate the This means that adaptive control using μ as a parameter can be preferably realized.

From this point of view, the present inventor has made the present invention as a result of repeated studies to provide a suitable anti-skid control method in the current vehicle brake system by using a reference vehicle speed signal based on the above-mentioned absolute vehicle speed. This is what led to this.

[Purpose of the invention]

An object of the present invention is to realize braking control that can automatically adapt to various road surfaces by applying a reference vehicle speed signal that can be regarded as an absolute vehicle speed to anti-skid control.

Another object of the present invention is to prevent wheel lock while maintaining a favorable slip ratio between the road surface and the wheels, thereby achieving effective use of braking force and preventing unnecessary extension of braking distance. There it is.

Another object of the present invention is to maintain the road ml and the preferable slip ratio of the wheels, effectively maintain the side force of the vehicle, and prevent the occurrence of turning of the vehicle.

[Summary of the invention]

The gist of the present invention, which has been made to achieve the above-mentioned various objects, is that in a four-wheeled vehicle, during anti-skid control accompanying the detection of a sudden drop in wheel speed during braking, one of the two rear wheels The brake force on one of the wheels is released, and the wheel speed of this wheel is detected and used as a reference vehicle speed signal, and the brake force on the other three wheels is determined by the reference vehicle speed signal and the wheel speed signal of each wheel. A method of controlling an anti-skid 10 is characterized in that the control method is controlled to maintain a predetermined slip ratio by comparison with the above.

In the above V, the wheel speed signal obtained from the wheel whose brake force has been released can be regarded as approximately indicating the vehicle speed signal, and therefore is used as the reference vehicle speed signal V.
(hereinafter referred to as vehicle law iV).

However, along with the wheel speed signal υl+"2+υ3 (hereinafter referred to as wheel speed -1vffi+v!) for the three wheels of the pond, these wheel speeds can be detected as analog signals (voltage signals) or digital signals using an appropriate speed sensor. do it.

In comparison with the vehicle speed V, the slip ratio (V-υ/V) is the target value when controlling the braking force of the other three wheels.
is generally in the range of 10 to 30%, preferably 20%.

The brake hydraulic control device used in concretely realizing the method of the present invention can be one proposed as a known anti-skid device as it is or with appropriate modifications. It is equipped with a hydraulic pressure reducing means for reducing the hydraulic pressure in the brake system, a hydraulic pressure holding means, and a repressurizing means for transmitting the hydraulic pressure from the accumulator etc. to the brake system again. It is constructed in such a way that switching is performed using a solenoid valve or the like.

[Embodiments of the invention]

An embodiment of the method of the present invention will be briefly explained below.

In the figure, 1.2 indicates the left and right front wheels of a four-wheeled vehicle, and 3.4 indicates the left and right rear wheels of the same. 5.6.7.8 is a brake device installed on each wheel, 9.10.11.12 is a hydraulic control device interposed between these brake devices and the master cylinder 13, and the mask cylinder 13 and each Normally, the brake equipment communicates with each other, and during anti-skid control, the hydraulic pressure in the brake equipment is reduced, held, and re-pressurized by inputting signals to reduce, hold, and re-pressurize the brake oil pressure.Even the operation is specific. It consists of a combination of a shut valve that closes the flow path, a modulator, a pressure oil pump, an accumulator, an electromagnetic switching valve, etc.

14 is a brake pedal, and 15 is a hydraulic pressure transmission pipe. 1
6.17.18.19 is a speed sensor assembled to each wheel, which detects the rotational speed of the wheel and inputs this detection signal to the anti-skid control circuit 20.

Note that 21 is a handle for turning the two front wheels 1.2 in any direction.

In the above-described configuration V, the anti-skid control circuit 20 starts anti-skid control by detecting a sudden drop in wheel speed during braking. This can be done according to known methods by comparing the actual wheel speed with a condensed wheel speed signal that decreases at a constant rate.

In the control in this embodiment, the hydraulic control circuit 12 is activated to release the brake hydraulic pressure of the brake device 8 for the left rear wheel 4 at the same time as the anti-skid control is started.

The reason why the brake hydraulic pressure of the left rear wheel is released here is because the vehicle is making a normal turn as shown in the figure and the left rear wheel is the inside wheel, and the braking force of this inside wheel is on the outside of the turn. This is because they contribute less to braking than wheels. Note that this selection may be made based on the detection signal of a rotational direction detection means of the handle 21 provided.

Furthermore, when the vehicle is not turning, either of the two rear wheels may be selected.

When the brake hydraulic pressure of the left rear wheel is released, the left rear wheel becomes a so-called rolling wheel and rotates at a speed corresponding to the traveling speed of the vehicle.The vehicle speed V at this time is detected by the speed sensor 9 as the wheel speed. Detected as .

Then, with respect to this vehicle speed V, the wheel speed T of the other three wheels is
I, , +7. , +13, and for wheels with a tendency to lock, for example, the hydraulic control device of each wheel system is
The operation is controlled and the predetermined brake oil pressure is released.

transmitted to the rake device 5.6.7. Trench system 4 circuits 2
At 0 (V-T)/V) 20 (%), a brake oil pressure release signal is output, and V-rr/V (20 (%)
%), it is possible to configure a brake system that outputs brake hydraulic pressure.

According to the above, the brakes on the front two wheels and the rear wheel are used to perform braking on the vehicle's braking side while maintaining a suitable amount of slip between them and the road surface, and to perform favorable braking operations that are not affected by the state of the road surface μ. However, since the above-mentioned embodiments have been shown to make it easier to understand the method of the present invention, the actual equipment to which such a method is applied is not limited to this, and for example, hydraulic control The device may be of a single unit type, or may be a two-system control system with cross piping.

〔Effect of the invention〕

According to the method of the present invention described above, the braking force of each wheel can be controlled while maintaining a suitable slip ratio without being affected by the road surface μ condition based on a signal that can be substantially regarded as the vehicle speed. In addition to being effective, it also prevents unintentional vehicle turns by preventing an extension of the braking distance and securing side force, making it extremely useful.

[Brief explanation of the drawing]

The drawing is a schematic diagram illustrating the configuration of a temporary brake hydraulic control system to which the method of the present invention is applied. 1.2.3.4... Wheels 5.6.7.8... Brake device 9.10.11.12... Hydraulic control device 13... Mask cylinder 14... Brake pedal 15. ...Hydraulic pressure transmission pipe 16.17.18.19...Speed sensor 20...
- Control circuit 21...handle.

Claims (1)

[Claims] 1. In a four-wheeled vehicle, during anti-skid control associated with detection of a sudden drop in wheel speed during braking, the braking force on one of the two rear wheels is released, and the brake force on this wheel is released. The wheel speed is detected and used as a reference vehicle speed signal, and the braking force of the other three wheels is controlled to maintain a predetermined slip ratio by comparing the reference vehicle speed signal with the wheel speed signal of each wheel. An anti-skid control method characterized by: 2. The anti-skid control method according to claim 1, wherein the inner wheel is selected as one of the rear wheels to which the brake force is released when the vehicle is turning.