JP2004359202A - Diaphragm for reservoir tank of master cylinder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the followability of a diaphragm by a simple structure, and to prevent a liquid passing-through hole formed in a liquid storage tank from closing a large diameter disk part of the diaphragm even when the level of working liquid is dropped. <P>SOLUTION: A diaphragm 15 comprises a first expansion-contraction part 20 of bellows shape which is expanded-contracted in the axial direction of a liquid storage tank 4, a second expansion-contraction part 21 of a small diameter cylindrical shape which is formed continuous to the first expansion-contraction part 20 and expanded-contracted in the radial direction of the liquid storage tank 4, and a large diameter disk part 22 to close a lower end of the second expansion-contraction part 21. Three circumferential projections 23 are formed on a bottom surface 22a of the large diameter disk part 22 to prevent the bottom surface 22a of the large diameter disk part 22 from closing the liquid passing-through hole 16 when the first expansion-contraction part 20. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a reservoir tank diaphragm of a brake master cylinder mounted on a motorcycle, and particularly to a vertically long reservoir tank integrally formed on one side of a cylinder body having a vertically long cylinder hole. The diaphragm.
[0002]
[Prior art]
Conventionally, in order to prevent the working fluid in the reservoir tank from coming into contact with the outside air as much as possible and to prevent the pressure acting on the working fluid from being changed in accordance with the change in the amount of the working fluid, the inside of the reservoir tank is changed. Contains a diaphragm. A reservoir tank diaphragm used in a master cylinder integrally provided with a cylinder body having a vertically long cylinder hole and a reservoir tank having a vertically long liquid storage chamber is formed into a small-diameter cylindrical shape that is long in the axial direction of the liquid storage chamber. A vertical fold is formed in the axial direction of the small-diameter cylindrical portion, and the bottom is closed by a large-diameter disk portion, and the vertical fold is formed so as to be able to expand and contract in the radial direction of the liquid storage tank. .
[0003]
In this diaphragm, an atmosphere chamber is formed by communicating the inside of the small-diameter cylindrical portion with the outside air, and the atmosphere chamber is expanded and contracted by the working fluid or the filled air so that the pressure acting on the working fluid does not change. In addition, the large-diameter disk portion prevents bubbles mixed in the working fluid from entering the master cylinder (for example, see Patent Document 1).
[0004]
Further, a bellows-like first expanding / contracting portion capable of expanding / contracting the liquid storage chamber in the vertical direction and a longitudinal fold formed continuously below the first expanding / contracting portion and formed in the axial direction to form the liquid storage chamber. A diaphragm having a small-diameter cylindrical second expanding / contracting portion capable of expanding / contracting in the radial direction and a large-diameter disk portion closing a lower end of the second expanding / contracting portion has also been proposed. In this diaphragm, The follow-up volume is obtained by expanding / contracting the first expanding / contracting section (for example, see Patent Document 2).
[0005]
[Patent Document 1]
JP-A-2000-255409 (FIG. 5 on page 5)
[0006]
[Patent Document 2]
JP-A-2001-140801 (FIGS. 1 and 2 on page 2-3)
[0007]
[Problems to be solved by the invention]
However, in the diaphragm of Patent Document 1 described above, the small-diameter cylindrical portion must be formed long in the axial direction of the liquid storage chamber in order to increase the follow-up volume. However, it was difficult to form a long film.
[0008]
Further, in the diaphragm disclosed in Patent Document 2, although the following volume can be increased by the first expanding / contracting portion, the first expanding portion is provided in a state where the level of the hydraulic fluid in the liquid storage chamber is reduced due to lining wear of the friction pad or the like. When the bellows expands, the large-diameter disk portion descends with the expansion of the bellows and comes into close contact with the bottom wall of the liquid storage chamber, possibly closing the liquid passage hole.
[0009]
Therefore, the present invention can improve the followability of the diaphragm with a simple structure, and even when the liquid level of the hydraulic fluid is reduced, the liquid through hole formed in the liquid storage chamber can be replaced with the large-diameter disk portion of the diaphragm. It is an object of the present invention to provide a diaphragm of a reservoir tank for a master cylinder which is not blocked.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the present invention integrally forms a cylinder body having a vertically long cylinder hole, a reservoir tank including a vertically long liquid storage chamber and a lid member for closing an upper opening of the liquid storage chamber. Then, the liquid storage chamber and the cylinder hole communicate with each other through a liquid communication hole formed in a bottom wall of the liquid storage chamber, and the liquid storage chamber has a liquid chamber on the bottom wall side in the liquid storage chamber. A master cylinder provided with a diaphragm partitioned into an atmosphere chamber on the side of the lid member, wherein the diaphragm has a bellows-shaped first expansion / contraction section at the top capable of expanding and contracting the liquid storage chamber in a vertical direction. A small-diameter cylindrical second expanding / contracting portion which is formed continuously with the first expanding / contracting portion and which is formed of a vertical fold which enables expansion and contraction of the liquid storage chamber in a radial direction, is formed at a lower portion; A large-diameter disk portion closing the lower end of the atmosphere chamber is integrated with the lower end of the second expanding / contracting portion. A protrusion or a recess is formed on the bottom surface of the large-diameter disk portion and / or the bottom wall of the liquid storage chamber, and when the first expanding / contracting portion is expanded, the liquid is formed by the bottom surface of the large-diameter disk portion. It is characterized in that the through hole is not blocked.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIGS. 1 to 3 show a first embodiment of the present invention. A master cylinder 1 of this embodiment is for outputting a brake fluid pressure for braking a rear wheel of a motorcycle, for example. In addition, a liquid storage chamber 4 of a reservoir tank 3 is integrally formed in a vertically elongated substantially cylindrical shape on one upper side of a vertically elongated substantially cylindrical cylinder body 2. The master cylinder 1 is mounted on the vehicle body by bolting brackets 2a, 2a formed on the cylinder body 2 to the vehicle body frame.
[0012]
The cylinder body 2 is provided with a vertically elongated bottomed cylinder hole 5 having an open lower end, and a piston 6 is inserted into the cylinder hole 5 in a liquid-tight and movable manner using a primary cup 7 and a secondary cup 8. At the same time, a hydraulic chamber 9 is defined between the piston 6 and the upper wall of the cylinder hole 5.
[0013]
A return spring 10 is contracted between the piston 6 and the upper wall, and the piston 6 is urged downward by a resilient force of the return spring 10 in a non-operating direction, that is, in a downward direction. Is restricted by contact with the head 12a of the push rod 12 locked to the circlip 11 engaged with the opening of the cylinder hole 5. The hydraulic chamber 9 is provided with a union hole 13 communicating therewith.
[0014]
The reservoir tank 3 has a liquid storage tank 4 integrated with the cylinder body 2 and a lid member 14 attached to an upper opening of the liquid storage tank 4, and a diaphragm 15 is sandwiched between these. . Inside the liquid storage tank 4, a vertically long cylindrical liquid storage chamber 4 a is provided, and the liquid storage chamber 4 a and the cylinder hole 5 are formed with a liquid through hole 16 and a relief port 17 formed in a bottom wall 4 b of the liquid storage tank 4. And the supply port 18 so that the hydraulic fluid F can flow between the liquid storage chamber 4a and the cylinder hole 5.
[0015]
The diaphragm 15 has a bellows-like first expanding / contracting section 20, a small-diameter cylindrical second expanding / contracting section 21 continuously formed below the first expanding / contracting section 20, and a large-sized block for closing a lower end of the second expanding / contracting section 21. And a radial disk portion 22. The first expanding / contracting portion 20 has a flange portion 20a projecting laterally formed at an upper end, and is provided with a bellows portion so as to be able to expand and contract vertically in the liquid storage chamber 4a. A plurality of vertical folds are formed in the second expanding / contracting section 21 in the axial direction, and the vertical folds enable expansion and contraction in the radial direction of the liquid storage chamber 4a.
[0016]
The large-diameter disc portion 22 has an outer diameter smaller than the inner diameter of the liquid storage chamber 4a, and the working fluid F can flow through a gap between the outer periphery of the large-diameter disc portion 22 and the liquid storage chamber 4a. In this manner, three circumferential projections 23, 23, 23 (projections of the present invention) are formed at equal intervals on the outer peripheral side of the bottom surface 22a.
[0017]
In the diaphragm 15, the flange portion 20a and the pressing plate 24 placed on the flange portion 20a are sandwiched between the upper end of the liquid storage chamber 4a and the lid member 14, and the lid member 14, the pressing plate 24 and the flange portion It is attached to the liquid storage chamber 4a by a bolt 25 inserted from above the 20a. Thereby, the diaphragm 15 is arranged such that the first expanding / contracting section 20 is disposed in the filled air left above the level of the hydraulic fluid F, and the second expanding / contracting section 21 is disposed in the hydraulic fluid F. , The bottom wall 4b side becomes the liquid chamber 26, and the inside of the diaphragm 15 on the lid member 14 side becomes the atmosphere chamber 27.
[0018]
A through hole 24 a communicating with the inside of the atmosphere chamber 27 is provided at the center of the holding plate 24. A passage leading to the through hole 24a is formed between the holding plate 24 and the lid member 14, and this passage is open to the outside on the side surface of the lid member 14.
[0019]
The present embodiment is configured as described above, and the master cylinder 1 for the rear wheel is in the state shown in FIG. 1 when the brake pedal is not operated and the brake pedal is not operated. When the brake pedal is depressed, the push rod 12 moves upward, pushing the piston 6 upward in the cylinder hole 5, and after the primary cup 7 closes the relief port 17, the hydraulic fluid in the hydraulic pressure chamber 9 is closed. F is gradually increased.
[0020]
The hydraulic fluid F pressurized in the hydraulic chamber 9 is sent from the upper union hole 13 to the caliper body of the rear wheel brake through the brake hose, and brakes the disk rotor that rotates integrally with the rear wheel. When the braking is released, the piston 6 returns to the original position by the elastic force of the return spring 10.
[0021]
As described above, when the piston 6 reciprocates in the cylinder hole 5 and the hydraulic fluid F flows between the cylinder hole 5 and the liquid storage chamber 4a, the diaphragm 15 separates the hydraulic fluid F and the air filled in the liquid storage chamber 4a. As a result, the first expanding / contracting section 20 expands or contracts in the up-down direction of the liquid storage chamber 4a, thereby effectively preventing the hydraulic fluid F from waving while following the liquid level change. In addition, the second expanding / contracting portion 21 quickly discharges bubbles generated in the working fluid F due to vehicle body vibration or the like into the filled air above the liquid level by expanding or contracting in the radial direction of the liquid storage chamber 4a. Like that.
[0022]
When the diaphragm 15 expands and contracts, the air in the atmosphere chamber 27 in the diaphragm 15 enters and exits from the outside via the through hole 24a and the passage between the holding plate 24 and the lid member 14. Therefore, the expansion or contraction action of the diaphragm 15 by the working fluid F and the filled air can be quickly performed. In addition, air bubbles generated in the hydraulic fluid F due to body vibration and the like, which cannot be discharged by the second expanding / contracting section 21, are separated by the large-diameter disk section 22 and prevent air bubbles from entering the master cylinder 1. Can be blocked.
[0023]
Further, when the level of the hydraulic fluid F in the liquid storage chamber 4a decreases due to abrasion of the lining of the friction pad or the like, the bellows of the first expansion / contraction section 20 expands, and the negative pressure state in the liquid storage chamber 4a is reduced. To avoid. When the braking operation is performed as described above in a state where the level of the hydraulic fluid F is lowered, the bellows portion of the first expanding / contracting portion 20 further expands, and accordingly, the bellows portion of the first expanding / contracting portion 20 is enlarged together with the second expanding / contracting portion 21. The large-diameter disk portion 22 descends, and the large-diameter disk portion 22 approaches the bottom wall 4b of the liquid storage tank. However, the three circumferential projections 23 formed on the bottom surface 22a of the large-diameter disk portion 22 form a bottom. The contact with the wall 4b prevents the bottom surface 22a of the large-diameter disc portion 22 from being in close contact with the liquid through hole 16. As described above, there is no possibility that the liquid communication hole 16 is closed, and even when the first expanding / contracting portion 20 is in the most expanded state, the working fluid F is removed from the space formed between the adjacent circumferential projections 23, 23. Can be introduced into the cylinder hole 5, and the master cylinder 1 can always be operated in a good state.
[0024]
FIGS. 4 and 5 show a second embodiment of the present invention, and FIGS. 6 and 7 show a third embodiment of the present invention, respectively. However, a detailed description thereof will be omitted.
[0025]
First, in the diaphragm 30 according to the second embodiment shown in FIGS. 4 and 5, the bottom surface 32 a of the large-diameter disk portion 32 connected to the lower end of the second expanding / contracting portion 31 has the diametrical direction of the large-diameter disk portion 32. (The concave portion of the present invention) is formed. As a result, even if the large-diameter disk portion 32 descends and the bottom surface 32a of the large-diameter disk portion 32 abuts against the bottom wall 4b of the liquid storage tank, the concave groove 33 is formed in the upper portion of the liquid passage hole 16. Is provided, the hydraulic fluid F can be introduced into the cylinder hole 5 through the concave groove 33 from the gap between the outer peripheral wall of the liquid storage chamber 4a and the outer periphery of the large-diameter disc portion 32.
[0026]
Next, in the diaphragm 40 according to the third embodiment shown in FIGS. 6 and 7, the large-diameter disc portion 42 is connected to the bottom surface 42 a of the large-diameter disc portion 42 connected to the lower end of the second expanding / contracting portion 41. A diametrical rib 43 is formed, and the rib 43 is a projection of the present invention. The width of the rib 43 is formed to be smaller than the diameter of the liquid passage hole 16, and the rib 43 abuts on the bottom wall 4 b of the liquid storage tank 4, and the bottom wall 4 b of the liquid storage tank 4 and the large-diameter disc portion 42. And a gap is also formed between the rib 43 provided on the liquid passage 16 and the liquid passage 16.
[0027]
In addition, the present invention is not limited to forming protrusions and recesses on the bottom surface of the large-diameter disk portion as in the above-described embodiments, but may form protrusions on the bottom wall of the liquid storage chamber, A concave portion communicating with the liquid through hole from the side may be formed, and a projection or a concave portion may be formed on both the bottom surface of the large-diameter disk portion and the bottom wall of the liquid storage chamber.
[0028]
The shape and number of the protrusions provided on the bottom surface of the large-diameter disk portion and the bottom surface of the liquid storage chamber are arbitrary. When the first expanding / contracting portion is expanded most, the large-diameter disk portion or the protrusion is formed on the bottom wall. The shape and the number are arbitrary as long as they do not block the formed liquid through-holes. Also, the concave portion provided on the bottom surface of the large-diameter disk portion or the bottom surface of the liquid storage chamber may have any shape or shape as long as it is a concave portion extending from the outer peripheral side of the large-diameter disk portion or the outer peripheral side of the liquid storage chamber to the liquid through hole forming portion. The number is arbitrary.
[0029]
【The invention's effect】
As described above, according to the present invention, since the diaphragm is provided with the first expanding / contracting portion and the second expanding / contracting portion, the followability of the diaphragm can be improved, and the level of the hydraulic fluid is reduced. In this case, even if the first expanding / contracting portion expands most, it is possible to prevent the bottom surface of the large-diameter disk portion from blocking the liquid passage hole and to always operate the master cylinder satisfactorily.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a master cylinder showing a first embodiment of the present invention. FIG. 2 is a cross-sectional view of a main part of a diaphragm showing a first embodiment of the present invention. FIG. FIG. 4 is a cross-sectional view of a main part of a diaphragm showing a second embodiment of the present invention. FIG. 5 is a cross-sectional view taken along line VV of FIG. 4. FIG. 7 is a sectional view taken along the line VII-VII in FIG.
DESCRIPTION OF SYMBOLS 1 ... Master cylinder, 2 ... Cylinder body, 3 ... Reservoir tank, 4 ... Reservoir tank, 4a ... Reservoir chamber, 4b ... Bottom wall, 5 ... Cylinder hole, 6 ... Piston, 14 ... Lid member, 15 ... Diaphragm, Reference numeral 16: liquid passage hole, 20: first expanding / contracting portion, 21: second expanding / contracting portion, 22: large-diameter disk portion, 22a: bottom surface, 23: circumferential protrusion, 24: holding plate, 33: concave groove, 43 …rib

Claims (1)

A cylinder body having a vertically elongated cylinder hole, a reservoir tank having a vertically elongated liquid storage chamber and a lid member for closing an upper opening of the liquid storage chamber are integrally formed, and the liquid storage chamber and the cylinder hole are formed. The storage chamber is communicated through a liquid hole formed in a bottom wall of the storage chamber, and the storage chamber is partitioned into a liquid chamber on the bottom wall side and an air chamber on the lid member side. In the master cylinder provided with a diaphragm to be arranged, the diaphragm is formed continuously with the first expanding / contracting portion, with a bellows-shaped first expanding / contracting portion capable of expanding / contracting the liquid storage chamber in the vertical direction at an upper portion, A large-diameter disk having a small-diameter cylindrical second expanding / contracting portion formed of a vertical fold capable of expanding and contracting in the radial direction of the liquid storage chamber at a lower portion, and closing a lower end of an atmosphere chamber in the diaphragm. Part is provided integrally with the lower end of the second expanding / contracting part, and the bottom of the large-diameter disk part is provided. And / or a projection or a recess is formed on the bottom wall of the liquid storage chamber so that the liquid passage hole is not closed by the bottom surface of the large-diameter disk portion when the first expansion / contraction section is expanded. A diaphragm for a reservoir tank of a master cylinder.

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