JPS5820549A - Fluid pressure controller of vehicle brake system - Google Patents

Abstract

PURPOSE:To prevent a rear wheel lock due to delay of a pressure drop in rear wheel brake fluid, by slidably fitting a fail safe piston into a valve body, slidably fitting a pressure reducing piston to a cylinder part of the fail safe piston and obtaining almost approximate rise and fall characteristic curves in brake fluid pressure. CONSTITUTION:A fail safe piston 9 with a stepped difference is slidably fitted to stepped cylinders 5, 6 of a valve body 1, and the first and second pressure reducing pistons 10, 11 are slidably fitted respectively to cylinder parts 9a, 9b of the piston 9. Further a stepped control piston 12 is slidably fitted to stepped cylinders 10a, 10b of the pressure reducing piston 10. This pressure reducing piston 10 is formed in such a manner as to appear with pressure receiving areas A4, A3 (A3>A4) for input-output fluid chambers a1, a2, and normally urged leftward by a holding spring 24. Further spring tension of said spring 24 is set to a specific value in such a manner that this pressure reducing piston 10 is stopped at application of a brake while moved to increase area of the output fluid chamber a2 at release of the brake.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a hydraulic pressure control device used in a vehicle brake system.

In general, when braking a vehicle, it is considered desirable to make the rear wheels lower than the front wheels due to the relationship between the loads applied to the front and rear wheels in order to prevent wheel locking. This is a so-called f a /-shi double-ring type pulp mechanism that controls the increase in hydraulic pressure transmitted to the rear wheel brake device from a predetermined hydraulic pressure value in relation to the increase in brake hydraulic pressure. is provided.

Then, the control characteristics of the corner point depressurization control are approximated to the Rimisaki distribution ratio according to the load loading state of the vehicle.
, for example, the break point value is possible! Various ideas such as the provision of an R mechanism (G.

By the way, this type of hydraulic pressure control device, which has been known in the past, is intended to control when the brake fluid pressure increases, in other words, to control the hydraulic pressure when the brake is applied. The characteristics of pressure reduction usually exhibit characteristics different from those of normal external pressure, and there is a risk that the drop in rear wheel brake pressure will be delayed and the rear wheels will lock depending on the operating conditions.

The present invention also solves a certain difficulty in the process of hydraulic pressure reduction control, which is caused by the fact that the brake hydraulic pressure on the rear wheel side lags behind the drop in hydraulic pressure in the mask cylinder.
The characteristic line of the rise and fall of brake fluid pressure is approximately approximated to obtain desirable braking control. By facing the pressure-receiving area A1 and facing the output liquid chamber leading to the rear wheel brake system of the vehicle with a large hydraulic pressure-receiving area A, it is possible to move under the different hydraulic pressure effects from these two liquid chambers. A control piston is provided as shown in FIG. and ``a valve body disposed opposite to the flow passage opening facing the input liquid chamber of the control piston and closing the opening of the front distribution passage when the wrinkle control piston moves a certain amount toward the input liquid chamber side; It faces the liquid chamber with a small hydraulic pressure receiving area M1, and faces the output liquid chamber with a large hydraulic pressure receiving area A4, so that it can move under the different hydraulic pressure effects from these two liquid chambers. A pressure reducing piston is provided, and six hold springs are arranged so as to bias the pressure reducing piston with a spring force F in the direction of the output liquid chamber. A hydraulic pressure control device for a two-vehicle brake system, characterized in that it is set to the relationship of (b).

It is in.

The present invention will be explained below based on embodiments shown in the drawings.
This example shows a book in which the vehicle brake system is applied to a double piping type in which the vehicle brake system is divided into two independent systems.

In the figure, 1 indicates the pulp, 2-3-4.5.
Reference numeral 6 denotes a stepped cylinder with concentric larger diameters from the small diameter part on the closed side toward the open side, and a threaded part 7 following the cylinder 6 with the largest diameter has a plug for closing the open end. 8 is screwed together.

Reference numeral 9 indicates a 7-air seal 7 pimeton which is slidably fitted to the cylinder 5.6, 10 is a first pressure reducing piston which is slidably fitted to the inner cylinder portion 91 of the 7-air piston 9, and 11 is a 7
The inner cylinder part 9b of the fail-safe piston 9 and the pulp are the second pressure reducing pistons that are slidably fitted to the cylinder 3 of the fail-safe piston 9, @1-second pressure reducing piston 10*11, The operation method will be explained later.

12 is a stepped inner cylinder cylinder 710m with Ml decompression piston lO
, 10bK stepped sliding-fit control piston, the large diameter end of which faces the A system's output fluid chamber am (communicated with the rear wheel brake system), and the small diameter end facing the A system's input fluid chamber ax (mask cylinder). (Communication) This control piston 12 is formed with a liquid flow path 121 that connects both sides of the large and small diameter ends, and the opening of the liquid flow path 121 to the input liquid chamber 9 is a valve that cooperates with the valve body 13 described later. It is provided so as to form a seat 12b. Reference numeral 14 denotes a control spring that applies a spring force to the control piston 12 in the direction of the output liquid chamber a, and includes a spring seat 15 assembled to the control piston 12 and a valve body 13 mounted on a cap-shaped head. Locking spring M116
It is stretched between the legs of the Reference numeral 17 denotes a hold sgelling, which locks the valve body 13, which is disposed so as to face the valve seat 12b of the control piston 12, in a state protruding from the head of the cap-shaped spring seat 1'6. It is a light load type.

18. 18 is a seal ring % 19 is an input port that connects the input fluid chamber 11 with a mask cylinder (not shown), 20 is an output port that connects the human power fluid chamber 1M to the front wheel brake system (not shown) K , 21 is an output (-) that connects the output liquid chamber a to the rear wheel brake device (not shown).

In the A base hydraulic pressure control mechanism with such a configuration, the first
If we consider the characteristics of the output hydraulic pressure with the decompression piston 10 as a fixed thing, when the hydraulic pressure is transmitted from the mask cylinder to the input liquid chamber a1 during vehicle braking, this input hydraulic pressure Pal will be Front wheel brake system (not shown)
, and the flow path 12m of the control piston 12.
21T
h to the rear wheel brake system (not shown).

Here, the cross-sectional area of the large and small diameter ends of the control piston 12 is defined as A.
, A1 (mu ■〉mu 1), assuming that the spring force of the control sgel ring 14 is one force, then P0~F/A@-mu,... (1) With Po as the hydraulic pressure breaking point, from here on If the output liquid chamber P0 is raised at a low rate of rise of 111mu1/mufu (ku1...-.omega.), then k. That is, the control piston 12 moves to the right in the figure against the corner spring 14 based on the difference in the hydraulic pressure acting force in the axial direction, and the valve seat 12b at the opening of the flow path 12m comes into contact with the valve body 13. # Closes the communication of the flow path 12m, and as the input hydraulic pressure P and □ increase, the control piston 12 repeatedly reciprocates in the axial direction, causing the output hydraulic pressure Pal to gradually increase. It is. In the hydraulic pressure control characteristic diagram of FIG. 2, the curve lI (c) indicates this characteristic line.

Next, considering the hydraulic pressure reduction characteristics during brake friction, the first
Assuming that the pressure reducing piston 12 is fixed as described above, the input hydraulic pressure Path falls as the brake is released. There is no change in the condition, and the two chambers 'jsal remain blocked.

The subordinate control piston 12 has a shoulder with a role of the first pressure reducing piston.
The valve body 13 moves until it is stopped by being stopped by the shoulder of the stepped inner cylinder, and then the differential pressure acting on the valve body 13 is applied to the hold spring 17. When the spring force is increased (b), the output liquid chamber a and the input liquid chamber are communicated with each other in a single layer, and a drop in the output liquid pressure P, , O is obtained. For this reason, when the player is released, the pressure reduction characteristic of the output hydraulic pressure remains at almost 1 until the input hydraulic pressure is sufficiently lowered.

In addition, in such a configuration, since the control piston moves in the direction of expanding the volume of the output liquid chamber when the input hydraulic pressure decreases, it is possible to make the cross-sectional area of the control piston sufficiently large. In this type, the spring force of the bending point must be extremely large due to the control characteristics at the time of external pressure, and there are disadvantages such as the need for a large-sized device.

Therefore, in the present invention, a 1gl pressure reducing piston 1O is provided which functions only to expand the volume of the output fluid chamber when the brake is released, independently of the control piston 12, to control the output fluid pressure when the brake fluid pressure is reduced; The delay in reducing the output hydraulic pressure is eliminated by making the characteristics as close as possible to the characteristic line during pressure increase.

To describe the configuration for this purpose, the first pressure reducing piston 1
0 is the piston force exerted between the seal ring 18 between the aforementioned control piston 12, the seal ring 22 interposed between the safe piston 9, and the cylinder 6, and f23. Depending on the input/output liquid chamber a1
, al are faced with A4*As (AI>A4) so that the area of receiving hydraulic pressure is smaller than that of the former, and the output liquid chamber a is normally suppressed and biased in the snow direction by the hold spring 24 with a spring force of F. ing. The first decompression piston 10 is designed so that it runs over when the brake is activated, and moves quickly to expand the output volume when the brake is released.
4 and the spring force F of the holdsgeling 24 in the above,
In relation to equation (1), it may be determined as follows.

However, δ is a positive constant, and it is desirable that the value is as small as possible so that the first pressure reducing piston and piston 10 move immediately when the brake fluid pressure is reduced, and δ is zero or a positive constant. Ashi, control piston 12 and M1 pressure reducing piston 10
It is practically desirable for δ to be 0 in order to allow the unitary movement of δ.

The above configuration is described for the hydraulic pressure control mechanism on the first system side of the double piping type hydraulic control device of the embodiment shown in the drawing.As is clear from this explanation, the four configurations can be used as they are. It is obvious that the present invention can also be applied as a single-system hydraulic control shaft device.

Next, the passive hydraulic pressure control mechanism of the other system in the above embodiment will be explained. In the figure, 25 is a balance cylinder that is slidably fitted to the balance cylinder 111 formed on the 1g2 pressure reducing piston 11, and one end of the balance cylinder 25 is slidably fitted to the balance cylinder 111 formed on the 1g2 pressure reducing piston 11. protrudes into the output liquid chamber □- and is opposed to the end of the control piston 12, and an axial reaction limit is set via the fail-safe knob 26. The other end of the second pressure reducing piston 11 is inserted into the input liquid chamber on the B system side and protrudes into the output liquid chamber on the released tip side of the second pressure reducing piston 11, and has a valve seat formed at the released tip of the second pressure reducing piston 11. In cooperation with 11b, it constitutes an on-off valve section that communicates and shuts off communication between the input and output liquid chambers S, 'b. Note that 27 is a set spring that lightly presses the balance piston 25 toward the A system side.

In such a configuration, the balance piston 25 is -A
-B The output liquid chambers of both systems *@hb@ have the same area, and the second pressure reducing piston 11 also faces the output liquid chambers of both systems *@@bH
・As the output liquid chamber on the A system side rises and falls with the same area, the liquid pressure in the B yarn side output liquid chamber rises.
This will result in a decline.

In addition, 27 is an input port that connects the B non-input liquid chamber b1 to the same type of mask cylinder, 28 is an output that connects the same person's power liquid chamber b1 to the B yarn side front wheel brake device, and 29 is an output liquid chamber. This is an output port connected to the B yarn side rear wheel brake device.

As described above, the vehicle brake system hydraulic pressure control device according to the present invention has a hydraulic pressure reduction characteristic that approximates the pressure increase characteristic line (A) as shown by break # (B) in FIG. This can be achieved with a relatively simple configuration, and this type of hydraulic pressure control eliminates the difficulty of rear wheel opening due to a delay in the drop in rear wheel brake fluid pressure, and its practical benefits are great. .

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of a hydraulic pressure control device according to the present invention, and FIG. 2 is a control characteristic diagram for increasing and decreasing hydraulic pressure by the same device. 1: Pal 2 is D, 2.3, 4.5.6: Cylinder, 7: Threaded part, 8: Flag, 9: Fail-safe piston, 9a: Inner cylinder cylinder part, 10: First pressure reducing piston, 10
aslOb: Stepped inner cylinder 7, 11: GZ pressure reducing piston, 11&: Balance cylinder, 11b: Valve seat, 12: Control piston, 12a
: flow path, 12b=valve seat, 13: valve body,
14: Breaking point spring, 15.16: Spring seat, 17: Holding ring, 18: Seal ring, 19: Input port, 20.2
1: Output port, 22: Seal ring, 23: Piston force, 24
: Hold spring, 25: Balance piston, 26: 7 Elisei 7 clip, 27: Input port, 28.29: Output port.

Claims (1)

[Claims] By facing the input liquid chamber leading to the mask cylinder with a small hydraulic pressure receiving area, and facing the output liquid chamber leading to the rear wheel brake system of the vehicle with a large hydraulic pressure receiving area. A control piston is provided so as to be able to move under the action of different fluid pressures from these two fluid chambers, and a control piston is provided with a flow path that communicates these two fluid chambers. A bending point suffler arranged to bias a spring force Fi, and arranged opposite to a flow path opening facing the input liquid chamber of the control piston, and move the control piston by a certain amount toward the input liquid chamber side. a valve body that sometimes closes the opening of the flow path; and a small hydraulic pressure receiving area in the input liquid chamber. By facing the single output liquid chamber with a large hydraulic pressure receiving area A4, different hydraulic pressure effects from these two liquid chambers can be achieved.
The pressure reducing piston is provided so as to be able to move in response to the received pressure, and a hold spring is provided so as to bias the pressure reducing piston with a spring force F in the direction of the output liquid chamber. The area and spring force are expressed by the following formula fO
A hydraulic pressure side device for a vehicle brake system, characterized in that it is set in the following relationship.