JPS6141660A - Master cylinder - Google Patents

Abstract

PURPOSE:To prevent a hydraulic fluid from scattering in the atmosphere, by partitioning off the inside of a reservoir tank of a brake master cylinder up and down with a diaphragm having a flange-form slinger part. CONSTITUTION:A diaphragm 9 is made up in a bellows from connecting a top plate 16, whose peripheral side is held between a reservoir tank 8 and a cap 11, to a bottom plate 14 via a flexible peripheral wall 17 having a waveform bend part, and a peripheral edge inside an opening part of the top plate 16 is yet more projected inward in a radial direction from a connection part with the flexible peripheral wall 17, forming a flange-form slinger part 18. When a liquid level inside the resorvoir tank drops due to wear in a brake pad and decrease in the hydraulic fluid, the bellows type diaphragm 9 well follows the liquid level drop whereby the flat bottom plate 14 makes sufficient contact with the liquid surface, serving as waving prevention.

Description

[Detailed Description of the Invention] L1! TECHNICAL FIELD The present invention relates to a hydraulic mask cylinder for operating a disc brake, clutch, etc. of a vehicle.

For example, a disc brake on a motorcycle is operated by operating a piston of a mask cylinder via an operating lever, thereby forcing pressurized hydraulic fluid to a brake caliper.

The mask cylinder has a cylinder hole drilled in the main body, and a piston that is slidably fitted into the cylinder hole allows
A hydraulic chamber is defined in its front part. Further, a reservoir tank is provided, and the reservoir tank and the cylinder hole are communicated with each other by a supply boat and a relief boat, and hydraulic fluid is replenished from the reservoir tank to the hydraulic chamber according to the wear of the brake pads, and is also sent by the replenishment action. Excess hydraulic fluid is returned to the reservoir tank.

Figure 1 shows such a conventional disc brake mask cylinder for motorcycles, where 01 is the cylinder body and 02 is the cylinder body.
03 is a cylinder hole, 03 is a piston, 04 is a hydraulic chamber, 05 is an operating lever, 06 is a supply boat, 07 is a relief boat, and 08 is a reservoir tank.

The upper part of the inside of the reservoir tank 08 is partitioned into upper and lower parts by a diaphragm 09. The diaphragm 09 is a flat diaphragm having a wave-shaped bent portion 010, and its peripheral edge is connected to the upper end of the peripheral wall of the reservoir tank 08 and the cap 0.
It is sandwiched between 11 and 11. The cap 011 is provided with a ventilation hole, and the space above the diaphragm 09 communicates with the atmosphere through the ventilation hole. , 012 is a diaphragm plate provided between the cap 011 and the diaphragm 09, and this diaphragm plate 01
2 also has a middle part: ventilation hole formed.

The diaphragm 09 prevents solidification from entering the reservoir tank, and also follows fluctuations in the liquid level of the working fluid in the tank and is always in contact with the liquid level, thereby preventing undulations of the liquid level. It is provided for.

- However, this diaphragm 09 is usually made of rubber and is not completely permeable to the hydraulic fluid, so it has a long length.
After a period of time has elapsed, the hydraulic fluid that has seeped into the diaphragm 09 accumulates on the diaphragm, and this hydraulic fluid tends to scatter into the atmosphere through the vent provided in the cap due to fluctuations in the diaphragm or vibration of the vehicle. there were.

For this reason, in the mask cylinder shown in FIG. 1, the upper part of the diaphragm 09 is further divided by the diaphragm plate 012, but in the present invention, such a diaphragm plate is not installed, and the shape of the diaphragm is devised. This is intended to prevent the hydraulic oil from scattering by only using the same method.

For this reason, in the present invention, the inside of the reservoir tank is partitioned with a bellows-shaped diaphragm that can be expanded and contracted up and down,
A flange-shaped liquid draining portion is provided on the inner circumferential edge of the top plate opening of the diaphragm and protrudes radially inward along the circumferential edge.

According to the present invention, since the diaphragm is a lantern-like bellows-shaped diaphragm, when the working fluid accumulated at the bottom of the diaphragm tries to rise along the peripheral wall of the diaphragm, the horizontal It is difficult for the hydraulic fluid to rise because it is obstructed by the wavy bends in the direction, and the hydraulic fluid that reaches the upper part turns around at the liquid cutter that protrudes radially inward and falls downward.

Therefore, it is possible to prevent the hydraulic fluid from scattering into the atmosphere without providing a diaphragm plate as in the conventional device.

In addition, the bellows-shaped diaphragm has a wave-shaped bent part parallel to the liquid level, so it has good followability to changes in the liquid level, and the lower flat part can make sufficient contact with the liquid level. Great action and effect can be obtained in preventing surface deformation and waving.

1 Lid 1 FIG. 2 shows an embodiment of the present invention. This embodiment is a mask cylinder for a disc brake of a motorcycle similar to that shown in FIG. A hydraulic chamber 4 is defined. The piston 3 is actuated by an operating lever 5, and is connected to the cylinder hole 2 and the reservoir tank 8.
is communicated with via a supply boat 6 and a relief boat 7.

The upper opening of the reservoir tank 8 is covered with a cap 11, and a bellows-shaped diaphragm 9 is sandwiched between the cap 11 and the reservoir tank 8.
The upper part of the inside of the reservoir tank 8 is partitioned into upper and lower parts by this diaphragm 9. A vent hole 12 is provided in the cap 11, and a space 13 above the diaphragm 9 communicates with the atmosphere via the vent hole 12. The disk-shaped bottom plate 14 of the diaphragm 9 comes into contact with the liquid level of the hydraulic fluid in the reservoir tank 8 to suppress the liquid level from tilting, and the diaphragm 9 expands and contracts up and down in response to fluctuations in the liquid level. 15 is a level gauge for detecting this liquid level.

The diaphragm 9 includes a top plate 16 and the bottom plate 14, the outer periphery of which is sandwiched between the reservoir tank 8 and the cap 11.
The top plate 16 has a bellows shape connected via a flexible circumferential wall 11 having a wave-shaped bent portion, and the inner circumferential edge of the opening of the top plate 16 further protrudes radially inward from the connection with the flexible circumferential wall 17 to form a flange-like shape. A liquid drain section 18 is formed.

Since the main part of the diaphragm 9 is made of a rubber material, as mentioned above, the permeated hydraulic fluid tends to accumulate in the diaphragm over time. This hydraulic fluid accumulates on the bottom plate 14, but due to the movement of the mask cylinder, the deformation movement of the diaphragm, etc., the hydraulic fluid adhering to the flexible peripheral wall 11 rises along the cough peripheral wall as shown by the dotted line in FIG.

When the liquid that has risen in this way reaches the top surface of the top plate 16, it passes through the ventilation holes 12 and scatters into the atmosphere.
In this embodiment, since the flange-shaped liquid drain part 18 protrudes from the upper part of the flexible peripheral wall 17, the liquid rising along the peripheral wall 17 is blocked by the liquid drain part 18. Falling downward from the bottom. Further, since the flexible peripheral wall 17 is provided with a wave-shaped bent portion, the rise of the liquid is also blocked by this wave-shaped portion, and almost no liquid reaches the upper surface of the top plate 16 after going around the inner peripheral edge portion 19 of the liquid cutter portion 18. Moreover, the inner circumferential edge 19 of the liquid drain section 18 is located at a sufficient distance from the wall surface of the reservoir tank 8, and even if there is liquid that goes around the inner circumferential edge 19 and reaches the upper surface of the top plate 16, the vent hole 12 is becoming difficult to reach.

As this mask cylinder is used for a long period of time, the fluid level in the reservoir tank decreases due to an increase in the stroke of the caliper piston due to wear of the brake pads, a decrease in hydraulic fluid due to the permeation effect, etc., but the diaphragm As described above, the bellows shape 9 closely follows this drop in the liquid level, and the flat bottom plate 14 comes into sufficient contact with the lowered liquid level to prevent waving.

FIG. 4 shows the state of the diaphragm 9 when the liquid level drops as described above. At this time, as a result of long-term use, the amount of liquid permeating inside the diaphragm has also increased, but as shown in the figure, the corrugations of the peripheral wall 17 have opened and the slope has become large, so the liquid is flowing around the diaphragm. ! It is difficult for the liquid to rise along the line 17, and the liquid drain part 18 is inclined with the inner peripheral edge part 19 facing down, making it easier for the liquid to fall. In other words, the effect of the diaphragm 9 on preventing the hydraulic fluid from scattering is further improved by lowering the fluid level. Also, Zhou W1
The liquid adhering to the outside of 17 also tends to fall downward, and the amount of liquid that permeates from this part decreases.

In FIG. 5, in order to avoid the level gauge part 15 provided in the reservoir tank 8 and protruding inward, the flexible peripheral wall 17 of the diaphragm 9 is not shaped cylindrical as in the previous embodiment, but has a conical shape. Another example is shown below. In this embodiment, the area of the bottom plate 14 is somewhat reduced, and the effect of preventing the liquid level from falling is slightly reduced, but the liquid adhering to the outside of the flexible peripheral wall 11 tends to fall, and the liquid is easily removed from this part. It can prevent seepage and permeation of liquid.

In the embodiment shown in FIG.
A protrusion 20 opposite to 9 is protruded from the cap 11.

When the diaphragm 9 contracts upward, the air inside the diaphragm 9 moves upward as shown by arrow a, and the air inside the diaphragm 9 moves upward as shown by the arrow a.
However, as the air moves, the liquid on the surface of the flexible peripheral wall 17 also moves upward. However, after this liquid passes the inner circumferential edge 19 of the liquid drain part 18, it does not move in the direction of the arrow a along with the air due to the difference in mass with the air, but due to inertia it hits the protrusion 20 and adheres thereto, and then, as indicated by the arrow so that it separates and falls.

In FIG. 7, the liquid draining part 18 is provided so as to be inclined in the F direction from the beginning, so that the liquid rising along the peripheral wall 17 can be made to fall downward more reliably. Also top plate 1
The liquid on the upper surface of the container 6 can also fall downward due to the slope of the liquid draining part 18.

In the embodiment shown in FIG. 8, a protrusion 21 is provided on the upper surface of the top plate 1G, and a protrusion 22 opposite to the protrusion 21 is attached to the cap 11.
The colliding strips 21 and 22 form a maze, making it difficult for the liquid to reach the inner circumferential wall surface 23 of the cap 11.

In this embodiment, the liquid drain section 18 is also inclined downward to achieve the same effect as in FIG. 7.

In each of the above embodiments, the ventilation holes are provided in the peripheral wall of the cap 11, but the ventilation holes may be provided in the center of the upper part of the cap.

As described above, in the present invention, the upper part of the interior of the reservoir tank is partitioned by a bellows-shaped diaphragm that is vertically expandable and retractable, and the diaphragm is provided at the periphery of the opening above the diaphragm in a radial direction along the periphery. A flange-shaped liquid cutter that protrudes inward prevents the hydraulic fluid collected at the bottom of the diaphragm from scattering into the atmosphere, and also improves the ability of the diaphragm to follow changes in the level of the hydraulic fluid in the reservoir tank. It has a good effect on preventing the liquid level from tilting and waving.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view showing a conventional mask cylinder, Fig. 2 is a side sectional view showing an embodiment of the present invention, Fig. 3 is an enlarged view of the circled part in Fig. 2, and Fig. 4. 3 is a drawing showing the state when the liquid level is lowered, and FIGS. 5 to 8 are drawings similar to FIG. 3 showing other embodiments of the present invention. 1...Cylinder body, 2...!・Cylinder hole, 3...
Piston, 4...Hydraulic air, 5...Operation lever, 6.
...Supply port, 7...Relief boat, 8...
・Reservoir tank, 9...Diaphragm, 10...
Mounting screw, 11...Cap, 12...Vent hole, 1
3... Upper space, 14... Diaphragm bottom plate, is
- Level gauge, 16... Diaphragm top plate, 1
DESCRIPTION OF SYMBOLS 1...Flexible peripheral wall, 18...Liquid drain part, 19...Inner peripheral edge part, 20...Protrusion, 21.22...Protrusion, 23
...Inner circumference of the cap! surface.

Claims (1)

[Claims] The inside of the reservoir tank is partitioned by a bellows-shaped diaphragm that can be expanded and contracted up and down, and a flange-shaped liquid drain part that projects radially inward along the periphery is provided on the inner periphery of the top plate opening of the diaphragm. A master cylinder featuring: