JPH0611258Y2 - Master cylinder with hydraulic control valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a master cylinder with a hydraulic pressure control valve used for a two-system brake system, and particularly, when one system fails, The present invention relates to an improvement of the hydraulic pressure control function that can be released.

(Prior Art) In this type of master cylinder with hydraulic control valve, the main piston and the slave piston are slidably inserted into the cylinder hole, and the main pressure chamber, the slave piston and the cylinder hole are inserted between these two pistons. Each of the auxiliary pressure chambers is partitioned from the bottom portion, and a hydraulic pressure control valve is attached to the discharge portion formed in communication with the main pressure chamber. The hydraulic control valve has a plunger biased by a spring having a predetermined preload, and a poppet arranged so as to face a valve seat formed on the plunger.

The fluid pressure control valve is in an open state in which the poppet is separated from the plunger-side valve seat when the fluid pressure is below a predetermined value, but when the fluid pressure exceeds a predetermined value, it is in a closed state in which the poppet is seated on the plunger-side valve seat. . As a result, in the hydraulic pressure control valve, when the hydraulic pressure exceeds the predetermined value, the hydraulic pressure on the inlet side communicating with the main pressure chamber (this hydraulic pressure is the same as the hydraulic pressure on the front wheel side). ,
The hydraulic pressure on the outlet side that communicates with the brake device on the rear wheel side is controlled to be reduced.

However, if such control by the hydraulic control valve is performed even when a failure occurs in the brake circuit on the front wheel side, a problem of insufficient braking force will occur. Therefore, conventionally, when the system on the front wheel side fails, the hydraulic pressure control function of the hydraulic pressure control valve is canceled. Specific examples thereof include European Patent Application Publication No. 0157158.
As described in Japanese Patent Publication No. JP-A-2003-264, there is known a technique in which when the secondary piston excessively strokes, the flange portion pushes the side portion of the poppet and swings the poppet so that the poppet is separated from the valve seat on the plunger side. Has been.

(Problems to be solved by the invention) In the conventional technique in which the poppet is swung, a part of the poppet has to be projected into the hole of the master cylinder, so that the hydraulic pressure control valve is still attached. Then, the piston cannot be taken out of the cylinder hole for part replacement or the like.

Also, since part of the secondary piston directly contacts the poppet, excessive force may be applied to the poppet due to dimensional accuracy restrictions, which may damage the poppet or cause the rocking poppet to damage the inner wall of the cylinder hole. It may also damage the piston cup.

It is an object of the present invention to provide an improved technique in which the piston can be removed even with the hydraulic pressure control valve assembled, and the poppet is not subjected to excessive force.

(Means for Solving the Problems) In this invention, the control function of the hydraulic control valve is canceled by utilizing the magnetic force of the permanent magnet.

That is, in this invention, as shown in FIG. 1 corresponding to the embodiment, the poppet 44 can be moved to a position where it cannot be seated on the valve seat 38c, and the sub piston 1 in the cylinder hole 12 can be moved.
When the movable body 46 and the poppet 44 are excessively stroked, a movable body 46 that moves to a position facing the poppet 44 is provided. One of the movable body 46 and the poppet 44 is a magnetic body and the other is a permanent magnet. And can be attracted to each other by magnetic force.

(Operation) During normal operation, since the movable body 46 and the poppet 44 are separated from each other, the influence of the magnetic force can be ignored. However, when a failure occurs in the brake circuit on the front wheel side and the secondary piston 16 makes an excessive stroke, the movable body 46 moves to a position facing the poppet 44, and the magnetic force thereof attracts the poppet 44. As a result, the poppet 44 cannot be seated on the valve seat 38c on the plunger side, and the control function of the hydraulic control valve is released.

Since the magnetic force acts across the gap, it is not necessary to project the upper portion of the poppet 44 into the inside of the cylinder hole 12 under normal circumstances. Therefore, the slave piston 16 can be easily taken out of the cylinder hole 12 even with the hydraulic pressure control valve assembled, and the slave piston 16 itself does not apply an excessive force to the poppet 44. Therefore, the poppet 44 is not damaged.

(Embodiment) An embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a cross-sectional view of a tandem master cylinder equipped with a hydraulic pressure control valve in the vicinity of the hydraulic pressure control valve.

A cylinder hole 12 having a uniform diameter and extending along the axis is formed in the cylinder body 10 of which only a part is shown. A sub piston 16 having a piston cup 14a and a main piston 18 having a piston cup 14b are slidably inserted into the cylinder hole 12. Both pistons 1
6 and 18 have the same axis, and their intervals are defined by a cup-shaped retainer 20 and a bolt 22. The chamber 24 defined by the cup seals 14a and 14b between the two pistons 16 and 18 is the main pressure chamber, and the chamber between the sub piston 16 and the bottom of the cylinder hole, which does not appear in the figure, is the sub pressure chamber. is there. In the main pressure chamber 24 and the sub pressure chamber,
A return spring 26 is provided for each of the pistons 16, 18
Is in the return position as shown in the figure unless the pressing force from the push rod is applied to the right end of the main piston 18. In this return position, the release hole 28 and the hydraulic fluid supply hole 30 leading to a reservoir (not shown) are located on both sides of the piston cup 14b of the main piston 18, and the hydraulic pressure is provided on the right side of the piston cup 14a of the slave piston 16. Control valve 5
A discharge hole 32 serving as a communication passage to 0 is located.

The housing 34 of the hydraulic control valve 50 is composed of two members 34a and 34b screwed together. In the housing 34, one end of one member 34a is screwed to the boss portion 10a of the cylinder body 10 to communicate with the discharge hole 32, while the other member 34b has an outlet 36 at the end thereof. Piping is connected to the wheel cylinder on the rear wheel side. In the housing 34, a stepped plunger 38 having a through hole 38a in the center is provided. When the hydraulic pressure is low, the plunger 38 receives the force of the preload spring 40, and the intermediate flange portion 38 a causes the member 34 to move.
It hits the step portion 34c on the b side and is in a stationary state. However, the hydraulic pressure increases and the seal ring 42 around the plunger 38
When the force acting on the effective difference area portion defined by a and 42b overcomes the force of the preload spring 40, the plunger 38 moves upward in the drawing. As a result, when the central protruding portion 44a of the poppet 44 is seated on the valve seat 38c at the upper end of the plunger 38, the hydraulic pressure control valve 50 thereafter controls the hydraulic pressure on the outlet 36 side to be reduced compared to the main pressure chamber 24 side. .

Therefore, in order to cancel the pressure reduction control by the hydraulic pressure control valve 50, it is sufficient that the central protruding portion 44a of the poppet 44 cannot be seated on the valve seat 38c. The plunger 38 is movable upward until its step 38d abuts the step 34d of the member 34a. Therefore, when the system on the front wheel side fails, the central protruding portion 44a of the poppet 44 may be separated from the valve seat 38c by a distance larger than the moving amount of the plunger 38.

Here, while the cylinder body 10 and the sub piston 16 are formed of a non-magnetic material such as aluminum,
The poppet 44 is made of an iron-based material that is a magnetic material, and a cylindrical permanent magnet 46 is attached to the end of the cylindrical portion 16a of the secondary piston 16 as a movable body. The poppet 44 made of a magnetic material is normally used for the valve spring 4
By the force of 8, the bottom surface of the peripheral side portion 44b is laid on the side of the member 34a. In that state, the upper portion 44 of the poppet 44
Although c is located in the discharge hole 32, it does not protrude into the cylinder hole 12. Therefore, the slave piston 16
The poppet 44 does not hinder at all. On the other hand, when the system on the front wheel side fails, the secondary piston 16 makes an excessive stroke and the movable body 46 made of a permanent magnet moves to a position facing the poppet 44. Therefore, the poppet 44 is attracted to the movable body 46 by the magnetic force, and the central protrusion 44a cannot be seated on the valve seat 38c.

It should be noted that the movable body 46 may be formed of a magnetic body and the poppet 44 may be formed of a permanent magnet, contrary to the one shown in the drawing. In that case, the movable body 46 may be formed integrally with the tubular portion 16a of the slave piston 16. From the standpoint of facilitating the manufacture, the main body of the secondary piston 16 is formed into the tubular portion 1.
It may be separated from the portion 6a.

(Effect of the Invention) According to this invention, since the control function of the hydraulic pressure control valve 50 is released by utilizing the magnetic force, the hydraulic pressure control valve 50 is released.
It is possible to take out the slave piston 16 and the like inside the cylinder hole 12 to the outside without removing the cylinder. Moreover, it is possible to prevent the poppet 44 from being forced through the slave piston 16 and to prevent damage to the poppet 44 and its peripheral portion. It can be avoided in advance.

[Brief description of drawings]

FIG. 1 is a sectional view showing an essential part of an embodiment of the present invention. 12 ... Cylinder hole, 16 ... Secondary piston, 38c ...
Valve seat, 44 ... Poppet, 46 ... Movable body.

Claims (1)

[Scope of utility model registration request] 1. A main piston and a slave piston are slidably inserted into a cylinder hole, and a main pressure chamber is defined between these pistons, and a slave pressure chamber is defined between the slave piston and the bottom of the cylinder hole. Moreover, a fluid pressure control valve is attached to the discharge portion formed in communication with the main pressure chamber, and the fluid pressure control valve is a spring urged by a spring having a predetermined preload and a valve seat formed on this plunger. In a master cylinder with a hydraulic control valve that has a poppet arranged opposite to, the poppet can be moved to a position where it cannot be seated on the valve seat, and the slave piston has excessively stroked in the cylinder hole. At this time, a movable body that moves to a position facing the poppet is provided, one of the movable body and the poppet is formed of a magnetic body, and the other is formed of a permanent magnet. Aspiration and then, moreover, the master when the hydraulic circuit is normal including cylinders, disposed between the hydraulic control valve with a master cylinder, not projecting towards the cylinder bore of the poppet from the discharge portion.