JPS5918055A - Live load sensing type hydraulic brake pressure controlling device for vehicle - Google Patents

Abstract

PURPOSE:To prevent vibrating force of hydraulic pressure in a bad path from being transmitted to a controlling valve by providing a spring between a piston for receiving the hydraulic pressure corresponding to live load and a piston for pushing hydraulic pressure controlling valve in the closing direction for force transmission. CONSTITUTION:A proportional pressure reducing valve 26 is provided between a master cylinder 10 and a rear wheel brake 16 and a first piston 23 for pushing said valve 26 in the closing direction is pressed by a second piston 27 through a spring 32. The second piston 27 is connected to a hydraulic pressure generator 20 of a suspension system to generate a force corresponding to live load on a vehicle. Thus, while the folding point of hydraulic control corresponds to the live load, the first piston is not affected by vibration of the second piston 27 caused by a bad road and the operation of the valve 26 does not become inaccurate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a system for distributing braking force from a brake master cylinder to a rear brake cylinder in order to approximate the ideal distribution of braking force between the front and rear wheels of a vehicle and to prevent the rear wheels from locking before the front wheels. This invention relates to a brake fluid pressure control device for a vehicle that controls supplied hydraulic pressure, and in particular to a load sensing brake fluid pressure control device for a vehicle that changes the corner point fluid pressure in its control characteristics in accordance with the vehicle load. It is.

Various configurations of conventional devices of this type are known, but the degree of freedom of installation on the vehicle is increased by using ′, W body pressure to detect the live load, and the hydraulic suspension protection As a suitable vehicle for vehicles equipped with
There is one described in Japanese Patent No.-105578 and shown in FIG. In the conventional device shown in FIG. 1, a fluid pressure generator 1 installed between the sprung portion and the unsprung portion of the vehicle receives fluid pressure proportional to the live load generated, and the first piston 2 is actuated by the valve 8. In a conventional device with such a configuration, in which the end of the piston 4, which is pushed in the direction of opening, is brought into contact with the end of the first piston 2, the second piston 4 is brought into contact with the second piston 2. When braking on a rough road under such conditions, the hydraulic pressure in the rear brake cylinder 5 became higher than the expected value, and a phenomenon was observed in which the rear wheels locked before the front wheels. This phenomenon occurs because the fluid pressure generated by the fluid pressure generator l vibrates due to the influence of the rough road, and both pistons 2.4 slide following this vibration.
This is due to the fact that the valve 8 is moved by a large amount that cannot be accommodated by hydraulic pressure control.

As a measure to prevent the above-mentioned phenomenon, it is possible to provide a vibration damping orifice in the middle of the circuit that guides the fluid pressure generated by the fluid pressure generator 8 to the second piston 4. Since the amount of movement of P8 to perform this is minute, the above phenomenon cannot be sufficiently prevented.

An object of the present invention is to prevent the first and second pistons from following vibrations of the fluid pressure received by the second piston due to the influence of a rough road, in a device that uses fluid pressure to sense a live load. , the purpose is to prevent the above phenomenon.

In order to achieve this object, in the present invention, a spring is interposed between the first piston and the second piston, and force is transmitted between the two pistons via this spring.

This transmits fluid pressure vibrations to the rear brake cylinder. , the spring constant of the transmission system is significantly 4 smaller than before, and the frequency of the fluid pressure vibrations that both pistons follow becomes smaller. The piston will no longer follow the flow, and therefore the valve will not be able to respond to hydraulic pressure control, and will not be opened a large amount.And with the above-mentioned configuration, when all hydraulic pressure control is being performed, the first piston 2nd against sliding
Since the sliding resistance of the piston is not affected, there is an advantage that there is less variation in hydraulic control characteristics compared to conventional ones.
In addition, the point at which the corner point liquid pressure starts to rise (relative to fluid pressure) is affected by variations in the gap between both pistons and variations in the spring constant of the spring in the conventional model.
In the present invention, the influence is only affected by the variation in the spring constant of the spring, and there is an advantage that there is little variation in the point at which the corner liquid pressure starts to rise.Furthermore, the sliding resistance of the second piston is increased to follow the vibration of the fluid pressure. There are advantages to getting it.

Hereinafter, in FIG. 2 for explaining an embodiment of the present invention based on the drawings, reference numeral 1 ( ) is a tandem type brake mask cylinder, which is actuated by depression of the brake pedal 11 and brakes the front wheels via a hydraulic circuit 12 . Hydraulic pressure is supplied to the cylinder 13 and to the rear wheel brake cylinder 16 via a hydraulic pressure circuit 14 and a load sensing type brake hydraulic pressure control device 15 interposed in the middle of this hydraulic pressure circuit.

The body 17 of the load sensing type brake fluid pressure control device 15 has an inlet 18 communicating with the brake mask cylinder 10 on its left side and an outlet 19 communicating with the rear wheel brake cylinder 16 1-1 and on its right side. The section has a boat 21 that communicates with a fluid pressure generator 20.

A guide 22 fixed to the body 17 and a first piston 28 slidably penetrating the guide 22 in a fluid-tight manner are provided in the left side of the body 17. In left 18 and aratren l-
:L 9 A liquid passage 24 is formed. A valve 26 comprising a land 23a of the first piston 23 and a ring-shaped cup 25 made of rubber is provided in the liquid passage 24□.

A second piston 27 is disposed in the right side of the body 17, and the second piston 27 and the guide 22i! 1 air chamber 2
8, and a cleansing pressure chamber 29 is formed on the right side of the second piston 27. This fluid pressure chamber 29 communicates with the boat 21 via a vibration damping orifice 30. Inside the air ¥28, there is a retainer 81 in contact with the right end of the first piston 2-3, a spring 82 stretched between the retainer 31 and the second piston 27, and a spring 82 stretched between the body 17 and the second piston 27. A spring 33 is provided.

When the second piston 28 slides to the right from the position shown in FIG. 2 and the land 28B comes into contact with the ring-shaped cam z5, the sealing effective diameter of the land 2B+1 is the outer diameter of the right side portion 23b of the first piston 2B. is larger than

In addition, the fluid pressure generator 20 utilizes the body pressure used for suspension of the suspension system in vehicles equipped with a fluid pressure type suspension system, and is specially installed in other vehicles.

The operation of the above configuration will be explained next.

When the vehicle is lightly loaded, the force generated on the second piston 27 by the fluid pressure supplied from the fluid pressure generator 20 to the fluid pressure chamber 29 is less than the force when the spring 82.33 is set, and the second piston 27 Located in the position of For this reason, the first piston 28 is arranged so that the hydraulic pressure of the rear wheel brake cylinder 16 is reduced to zero.
1 set load of ring 32 on section 8 of portion 23b! When the temperature exceeds the value divided by ℃, the valve 2 slides to the right from the position shown in the figure.
6 closes. When the valve 26 closes, the first piston 2:3 receives the hydraulic pressure of the rear brake cylinder 16 on the inner area S2 of the seal effective diameter of the land 23[1, and transfers the hydraulic pressure of the brake mask cylinder 10 on the annular area S2-8+. Receive pressure.

After the valve 2G is once closed, the hydraulic pressure increases in proportion to the increase in the hydraulic pressure in the brake mask cylinder 10.

The fold IJa-b-c in FIG. 8 indicates that when the vehicle is lightly loaded, the fluid pressure supplied to the fluid pressure chamber 29 is higher than when the vehicle is lightly loaded, so the second piston 27 is moved to the left from the position shown in the figure. The spring 32 is compressed by sliding toward the center, and the load on the spring 32 increases. Therefore, the liquid pressure at the break point increases, and the control characteristics become as shown by the break line a-de for the eighth bacteria.

FIG. 4 shows the correlation between the fluid pressure supplied from the fluid pressure generator 20 and the turning point fluid pressure. This is the point in time when the second piston 27 comes into contact with the eleventh retainer 31. In FIG. 4, the line Rho μ indicates the change due to the influence of the sliding resistance of the second piston 27. In order to avoid the influence of vibrations that occur on the fluid pressure in the fluid chamber 29 due to the influence of rough roads, the second piston 27
It is best to prevent the rear wheels from coming into contact with the retainer 81, but when the load is large, locking of the rear wheels is less likely to occur even if there are large variations in control performance.
Even if the second piston 27 is brought into contact with the retainer 81 when the load is large, there is almost no actual damage.

Furthermore, as is clear from FIG. 3, the embodiment shown in FIG. 2 functions like a so-called provocation valve;
It is also possible to perform a so-called mink-like action in which the hydraulic pressure in the rear wheel brake cylinder is not increased when the hydraulic pressure is at or above the turning point.

[Brief explanation of the drawing]

vA1 is a diagram showing a conventional device, FIG. 2 is a diagram showing an embodiment of the present invention, FIG. 3 is a control performance diagram thereof, and FIG. 4 is a diagram showing the relationship between liquid ratio at break point and fluid pressure. A certain IO...brake mask cylinder, 16...rear wheel play cylinder, 2
0... Fluid pressure generator, 23... First piston, 26
...Valve, 27...Second piston, 82...Spring Patent applicant Aisin Sei Co., Ltd. Representative Reio Nakai 309

Claims (1)

[Claims] A valve arranged in the middle of a hydraulic pressure circuit from a brake mask cylinder to a rear wheel brake cylinder, and a valve that controls the opening and closing of this valve and also rjg the valve by the hydraulic pressure of the hydraulic pressure circuit.
A load sensing type for a vehicle, comprising a first piston that is pushed in a direction to cause the valve to open, and a second piston that receives fluid pressure proportional to the load on the vehicle and pushes the first piston in a direction that opens the valve. In the brake hydraulic pressure control device, the first
A vehicle load sensing type % type % type having a configuration in which a spring is tensioned between the piston and the second piston, and force is transmitted between the two pistons via the spring.