JPS5917726Y2 - Master cylinder for motorcycle brakes - Google Patents

Description

[Detailed explanation of the invention] On an oil brake type motorcycle, if the master cylinder is installed in a place where vibration is relatively large, such as on the bundle near the brake lever, the boundary between air and fluid in the brake fluid reservoir. Foaming occurs on the surface of the master cylinder, and this phenomenon gradually becomes more intense, causing the entire fluid in the reservoir to foam, and the fluid containing minute bubbles reaches the pressure chamber of the master cylinder, and pushing the piston only collapses the bubbles, reducing the hydraulic pressure. A dangerous situation may arise in which the system does not occur.

The purpose of the present invention is to prevent the above-mentioned problems from occurring even when the master cylinder is installed in a place where vibrations are relatively strong, such as in a bundle, and will be explained with reference to the drawings as follows.

FIG. 1 shows a longitudinal section of a typical master cylinder, and in the figure, 1 is the master cylinder body, which is mounted on, for example, a motorcycle bundle.

2 is a check valve, 3 is a compression spring, 4 is a spring seat, 5 is a primary cup, 6 is a secondary cup, 7 is a piston, 8 is a piston stop, 9 is a circlip, 10 is a dust seal, 11 is a dust seal stopper .

The piston 7 engages a brake lever on the bundle, and when applying the brake, the piston 7 receives a force from the brake lever in the direction of the arrow.

The pressure chamber 16 on the left side of the piston communicates with the wheel cylinder via the check valve 2 and the discharge port 20.

A reservoir 17 is provided integrally with the body 1 and has brake fluid 21 inside.

15 is a relief port, and 18 is a supply port.

The upper part of the reservoir 17 is closed with a cap 12, a diaphragm plate 13, and a diaphragm 14.

19 is a non-return valve.

When the piston 7 is pushed in the direction of the arrow, hydraulic pressure is generated within the pressure chamber 16, and this hydraulic pressure is supplied to the wheel cylinder via the check valve 2 and the discharge port 20.

In this way, the surface of the brake fluid 21 is roughened on the server 1.
If the master cylinder is exposed to the air inside the reservoir, when the master cylinder is attached to the motorcycle bundle and vibrates violently, bubbles will occur at the interface between the air and the fluid 21, as mentioned above, and the bubbles will gradually become more intense and cause bubbles inside the reservoir. The entire fluid foams and the bubbles pass through the relief port 15 and supply port 18 and reach the pressure chamber 16. When you want to apply the brake, even if you push the piston 7 in the direction of the arrow, the pressure chamber 16
If the air bubbles in 6 are collapsed, hydraulic pressure will no longer be generated.

Furthermore, when the brake is operated in the operating direction, the piston 7 moves in the direction of the arrow and immediately before the primary cup 5 closes the first leaf port 15, the pressurized fluid in the pressure chamber 16 flows from the relief port 15 to the fluid 21. There is a problem in that the fluid blows up to the surface and bubbles occur at the interface between the air and the fluid 21.

Furthermore, when the brake is operated in the releasing direction, the piston 7 moves in the opposite direction of the arrow and immediately after the relief port 15 opens, the fluid jet reaches the liquid level of the fluid 21, causing foaming.

In order to solve the above problem, this invention integrates a brake fluid reservoir into the master cylinder, which communicates with the master cylinder through a relief port and a supply port, on the top of the master cylinder body fixed to the motorcycle body. One or more layers of filters covering the entire horizontal section are fixed to partition a chamber directly above both ports and one or more chambers above them, so that air bubbles generated in the upper chamber of the filter layer are separated from the lower chamber. It is made of a foamed resin plate that is thick enough to prevent the fluid from reaching the chamber, and the elasticity of the resin plate is used to enhance the buffering effect against the fluid jet, and the inside of the reservoir is partitioned by a single filter layer. Despite this, it is designed to promote the effect of reducing the oil pressure in the master cylinder when the brake is released.This will be explained below with reference to the drawings.

In the embodiment shown in FIG. 2, the inside of the reservoir 17 is divided into two upper and lower chambers 24.25 by means of a foamed resin plate 23 made of open cells.
It is divided into

The resin plate 23 is made slightly larger than the inner surface of the reservoir 17, and when attached to the annular step 26 on the inner surface of the reservoir, the outer circumferential surface elastically adheres to the inner surface of the approximately maximum inner diameter portion of the reservoir 17. , the central part protrudes downward due to buckling.

The resin plate 23 has a large number of continuous fine bubbles, and the cross-sectional diameter and length of the passages cut out from the continuous bubbles (corresponding to the thickness of the resin plate 23) allow the fluid to pass freely, but do not allow the passage of the bubbles. has been made small enough to prevent it.

Further, a hook 38 for attaching and removing the resin plate is attached to the foamable resin plate 23.

In this way, even if bubbling occurs at the interface between the air and fluid in the upper chamber 24, the bubbling of the fluid will not occur in the upper chamber 24.
4, it is possible to reliably prevent air bubbles from entering the lower chamber 25.

That is, the foamable resin plate 23 exerts a filter effect on the air bubbles generated in the chamber 24, and the air bubbles are removed from the chamber 24.
When the bubbles are about to flow to the 5 side, the bubbles are crushed by the fine passages formed from the continuous bubbles, and a defoaming effect is exerted.

When the brake is operated, the fluid jet from the relief port 15 collides with the resin plate 23 and passes through the fine passage in the resin plate 23, so the high-speed fluid jet flows into the chamber 2.
4, and foaming by the jet is prevented.

The material, degree of foaming, thickness, etc. of the resin plate 23 can be determined experimentally by considering the characteristics of the fluid used, the purpose of the master cylinder, etc., and installation using the stepped portion 26 as shown in FIG. By adopting this structure, the foamable resin plate 23 having an optimal shape can be easily attached.

In addition, direct installation is possible without the need for separate installation tools by an installer.

When the foamed resin plate 23 is elastically supported around it as shown in FIG. 2, when the brake is operated, the fluid jet resin plate 23 directed upward from the relief port 15 is appropriately pushed upward and bent, causing the jet energy is absorbed, and foaming by the jet is also prevented at this point.

Furthermore, since the volume of the chamber 25 can be increased and decreased relatively freely, the back pressure when the brake is released is reduced, and the performance when the brake is released is improved.

Since the fluid can freely pass through the resin plate 23, the fluid can be easily filled.

Furthermore, in the event that air bubbles enter the lower chamber 25, the chamber 2
Since the fluid in 5 is maintained in a static state, the bubbles gently reach the lower surface of the resin plate 23 due to buoyancy, and there is no risk of them reaching the pressure chamber 16 through the relief port 15 and supply port 18.

In addition, when it is necessary to bleed air from the pipe leading from the pressure chamber 16 to the wheel cylinder, such as when assembling or adjusting the brake device, hold the hook 38 on the resin plate 2.
3 can be easily taken out upwards, and the air bleeding work can be easily carried out as before.

As explained above, in this invention, the reservoir is divided into two or more upper and lower chambers with a single layer of filter, so the foaming phenomenon is limited to the uppermost chamber, and the single layer of filter acts as a resistor against the movement of bubbles, so the foamed fluid It is possible to reliably prevent problems caused by water reaching the pressure chamber.

In addition, since the single layer of the filter exhibits a defoaming effect, it is convenient for preventing harmful effects caused by air bubbles.

Furthermore, since the filter layer is made of a foam having a sufficient thickness, long fine passages can be formed within the filter layer, and the above-mentioned filter effect and defoaming effect can be further enhanced.

Furthermore, in the present invention, one layer of the filter is made of an elastic foamed resin plate 23, and the fluid jet ejected upward from the relief port 15 collides with the resin plate 23, causing the resin plate 23 to elastically bend. It is possible to sufficiently enhance the buffering effect against the fluid jet and reliably prevent foaming caused by the jet.

Furthermore, when the brake is released, the resin plate 23 bends upward in response to the high oil pressure in the master cylinder, promoting a decrease in the oil pressure in the cylinder.
(Compared to the case where the filter is formed of a single layer of rigid body), it is possible to promote the reduction of back pressure when the brake is released and improve the performance when the brake is released.

Moreover, in the present invention, since the outer periphery of the resin plate 23 is fixed to the approximately maximum inner diameter portion of the reservoir 17, a large diameter resin plate 23 is used.

Therefore, the amount of deflection of the resin plate 23 at the time of a collision or when the brake is released is increased, and the above-mentioned fluid jet buffering effect and oil pressure reduction promoting effect can be further enhanced.

In the illustrated embodiment, one layer of filter is used to divide the inside of the reservoir into two upper and lower chambers.
In order to increase the defoaming effect, it is also possible to use two or more layers of filters and divide the inside of the reservoir into three or more chambers, and in this way, the filter effect and the defoaming effect are further increased.

[Brief explanation of drawings]

Figure 1 is a vertical sectional view of a typical master cylinder, Figure 2
The figure is a partial vertical sectional view of the master cylinder according to the present invention.

Claims (1)

[Scope of utility model registration request] A brake fluid reservoir that communicates with the master cylinder through a relief port and a supply port is integrally provided on the upper part of the master cylinder body fixed to the motorcycle body, and the entire horizontal cross section of the reservoir is located within approximately the maximum inner diameter of the reservoir. The outer periphery of one or more layers of filters covering is fixed to define a chamber directly above both ports and one or more chambers further above the ports, and one layer of filters is formed of an elastic foamed resin plate, and the resin In addition to giving the plate sufficient thickness to prevent air bubbles generated in the upper chamber from reaching the lower chamber, the fluid jet ejected upward from the relief port improves the elastic properties of the resin plate. A master cylinder for motorcycle brakes, characterized in that the resin plate is elastically deflected when colliding with a resin plate, and when the brake is released, the resin plate is deflected upward in response to high oil pressure within the master cylinder.