JPH07329763A - Master cylinder - Google Patents

Abstract

(57) [Summary] [Purpose] The objective is to improve the degree of freedom in designing cup seals. [Structure] A cylinder main body 1 is provided with a bottomed cylinder hole 2 along its axial direction. Inside the cylinder hole 2,
The two pistons 3 and 4 are slidably arranged to define a plurality of chambers. Cup seals 9 to 12 are fixed to the outer circumference of the piston. A stopper cap 13 is fixed to the opening end of the cylinder hole of the cylinder body 1. On the inner surface of the bottom plate 13a of the stopper cap 13,
An annular seal member 14 is provided so as to project. Then, when the primary piston 3 retracts and comes into contact with the bottom plate 13a of the stopper cap 13, the sealing surface 3a of the primary piston 3 comes into contact with the seal member 14 and is sealed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a master cylinder used in a vehicle brake system.

[0002]

2. Description of the Related Art As a conventional master cylinder, for example, as described in Japanese Utility Model Publication No. 62-112962, a piston is slidably inserted into a bottomed cylinder hole formed in a cylinder body. A plurality of chambers are defined inside the cylinder hole. The above-mentioned actual development 62-112
The master cylinder described in Japanese Patent No. 962 is a tandem type master cylinder, and two pistons, a primary piston and a secondary piston, are arranged from the opening end side of the cylinder hole.

A cup seal is attached to the outer peripheral surface of each piston to ensure a predetermined liquid tightness between the outer peripheral surface of the piston and the inner peripheral surface of the cylinder hole. Also, on the inner peripheral surface on the opening end side of the cylinder hole,
The annular stopper plate is coaxially fixed, and when the primary piston moves toward the opening end side, the end surface of the piston comes into contact with the inner surface of the stopper plate, so that the opening of the primary piston is increased. Movement toward the end is restricted.

In some master cylinders, a stopper cap is attached instead of the annular plate-shaped stopper plate to restrict the movement of the primary piston toward the opening end of the cylinder hole. .
The stopper cap 30 has an opening portion into which a push rod can be loosely inserted in the central portion of the bottom plate, and is coaxially attached so as to cover the opening end side of the cylinder body 31, as shown in FIG. 7. The movement of the primary piston 32 is restricted by contacting the inner surface of the bottom plate 30a of the stopper cap 30 with the end surface of the primary piston 32.

[0005]

Generally, when the master cylinder is assembled in a factory and the brake fluid is injected into the brake circuit including the master cylinder, there is a vacuum filling step in which the inside of the brake circuit is evacuated in advance. . At this time, in the master cylinder having the conventional configuration as described above, the airtightness of the chamber formed in the cylinder hole 33 is adjusted to the piston 32.
It is ensured by the cup seal 34 attached to the.

The original role of the cup seal 34 is to ensure a predetermined liquid tightness with respect to the brake fluid in the cylinder hole 33 and to allow the piston 32 to slide in the cylinder hole 33. By providing the cup seal 34 with a vacuum sealability as described above, the degree of freedom in designing the cup seal 34 is lowered. That is, in order to ensure the above-mentioned vacuum sealability, the conventional cup seal 34 has, for example, a shape as shown in FIG.
The main lip portion 35 ensures a predetermined liquid tightness, and
The main lip portion 35 and the base lip portion 36 ensure a predetermined vacuum sealing property.

At this time, the base lip portion 36 is likely to generate a slight vibration due to friction generated by sliding on the inner peripheral surface of the cylinder hole 33 when the master cylinder is operated, and this vibration is transmitted to the entire rubber seal. This may affect the sealing performance of the main lip portion 35. Since it is extremely difficult to grasp the degree of this influence quantitatively,
When designing the cup seal shape, there is no choice but to make various kinds of shapes and to obtain an appropriate seal shape by trial and error.
Therefore, it takes a lot of time and money.

If the main lip portion 35 is shaped to withstand a high vacuum when the brake fluid is vacuum filled in a factory, resistance due to sliding increases and the main lip portion 35 is easily damaged. It is difficult to deal with because of problems. The present invention has been made in view of the above problems, and an object thereof is to improve the degree of freedom in designing a cup seal.

[0009]

In order to achieve the above object, a master cylinder of the present invention is such that a piston is slidably disposed in a bottomed cylinder hole formed in a cylinder body, and the cylinder is In a master cylinder having a structure in which a stopper cap is attached to the opening end of the hole, and the end surface of the piston abuts the inner surface of the bottom plate of the stopper cap, the movement of the piston in the opening end direction is restricted. On the inner surface of the bottom plate of the stopper cap, the sliding contact position between the inner peripheral surface of the cylinder hole and the outer peripheral surface of the piston, and the entire circumference of the position facing in the axial direction of the cylinder hole,
The feature is that a seal member is provided so as to project.

Alternatively, in the master cylinder of the present invention, as described in claim 2, the piston is slidably arranged in a bottomed cylinder hole formed in the cylinder body, and the cylinder hole is formed. A stopper plate made of a ring-shaped disc is coaxially attached to the inner peripheral surface on the opening end side of the piston, and the end surface of the piston abuts the inner surface of the stopper plate to move the piston in the opening end direction. In a master cylinder having a structure for restricting the seal member, a seal member is provided on the inner surface of the stopper plate with respect to the entire circumference of a position where the sliding contact position between the inner peripheral surface of the cylinder hole and the outer peripheral surface of the piston opposes in the axial direction of the cylinder. It is characterized by making it project.

Further, according to the first or second aspect of the invention, as described in the third aspect, the inner surface of the bottom plate or the stopper plate is provided along the entire circumference of the annular portion to which the seal member is attached, or It is characterized in that recesses are provided at a plurality of positions along the annular portion, and fitting portions that can be fitted into the recesses are provided in the seal member. Alternatively, as described in claim 4, with respect to the configuration of claim 1 or claim 2, through holes are respectively formed at a plurality of positions along the annular portion on the inner surface of the bottom plate or the stopper plate to which the seal member is attached. And a protrusion that can be fitted into the through hole is provided on the seal member.

Further, as described in claim 5, with respect to the structure of any one of claims 1, 3, and 4, the opening end surface of the cylinder hole which can come into contact with the seal member. Is provided, or at least one of the outer peripheral corners of the piston end surface that can come into contact with the seal member is notched to provide a tapered seal surface.

[0013]

According to the first aspect of the present invention, the annular sealing member is provided so as to project from the inner surface of the bottom plate of the stopper cap, so that when the piston is retracted until it abuts on the stopper cap, the inner peripheral side of the opening end of the cylinder hole. The seal member comes into contact with the sliding contact portion between the corner portion and the corner portion on the outer peripheral side of the piston end surface. As a result, in the state where the piston is retracted until it comes into contact with the stopper cap, a predetermined airtightness is ensured over the entire circumference of the sliding contact portion between the piston and the cylinder hole.

Since the sealing member does not come into sliding contact with the piston, it is not necessary to consider vibration during sliding, and it is necessary to contribute to sealing for liquid tightness when the master cylinder is operating. Absent. As a result, the cup seal fixed to the outer circumference of the piston is not required to have a vacuum sealability, and can be designed only from the viewpoint of the original purpose of the liquid tightness of the brake fluid and the slidability of the piston.

Further, as described in claim 2, the annular seal member is provided so as to project from the inner surface of the stopper plate so that when the piston retracts until it abuts on the stopper cap, the inner circumference of the opening end of the cylinder hole is increased. The seal member abuts on a sliding contact portion between the side corner portion and the piston end surface outer peripheral side corner portion. As a result, in the state where the piston is retracted until it comes into contact with the stopper cap, a predetermined airtightness is ensured over the entire circumference of the sliding contact portion between the piston and the cylinder hole.

Since the seal member does not come into sliding contact with the piston, it is not necessary to consider vibration during sliding, and it is necessary to contribute to the seal for liquid tightness during operation of the master cylinder. Absent. As a result, the cup seal fixed to the outer circumference of the piston can be designed only from the viewpoint of the original purpose of the liquid tightness of the brake fluid and the piston slidability without requiring the vacuum sealability.

The attachment of the annular seal member can be carried out, for example, by fitting the fitting portion of the seal member into the concave portion and fixing the fitting portion of the seal member. Thus, the recess facilitates positioning when assembling the seal member, and the seal member can be attached by a simple means of fitting the seal member into the recess.

Alternatively, for example, as described in claim 4, the present invention can be carried out by inserting the respective projections provided on the seal member into the through holes provided in the stopper cap or the stopper plate. Also in this case, the positioning at the time of assembling the seal member becomes easy, and the seal member can be attached by a simple means of fitting and inserting into the through hole.

It should be noted that it is preferable that the tip end portion of the protrusion is formed in a large diameter shape such as a mushroom shape in order to prevent it from coming off. Further, of course, other fixing means such as welding may be used together when fixing according to the above-mentioned claim 3 and claim 4. Further, as described in claim 5, when the piston or at least one of the pistons is provided with the tapered seal surface, the contact area of the seal member is increased and the airtightness of the seal member is improved.

[0020]

Embodiments of the present invention will be described with reference to the drawings.
First, the structure will be described. As shown in FIG. 2, the cylinder body 1 has a bottomed cylinder hole 2 along its axial direction. Inside the cylinder hole 2, two pistons 3,
4 are slidably arranged to define a plurality of chambers.

The above-mentioned two pistons are a primary piston 3 arranged on the opening end side of the cylinder hole 2 and a secondary piston 4 arranged on the bottomed side, and between the pistons 3 and 4, The predetermined space 2a (hydraulic chamber) is secured by the position regulation by the urging force of the bolt 5, the retainer 6 and the spring 7. Further, a predetermined space 2b (hydraulic chamber) is secured between the bottom side of the cylinder hole 2 and the secondary piston 4 by the urging force of the spring 8.

On the outer peripheral surface of the secondary piston 4, a primary cup seal 9 and a pressure
A cup seal 10 is attached to ensure a predetermined liquid tightness between the outer peripheral surface of the secondary piston 4 and the inner peripheral surface of the cylinder hole 2. Similarly, a primary cup seal 11 and a secondary cup seal 12 are attached to the outer peripheral surface of the primary piston 3 so that the outer peripheral surface of the primary piston 3 and the cylinder hole 2 are
A predetermined liquid tightness is secured between the inner peripheral surface and the inner peripheral surface.

In the primary piston 3, the outer peripheral side corner portion of the end surface on the opening side on the cylinder hole side is chamfered all around to form a tapered seal surface 3a. Similarly,
The inner peripheral surface side end surface of the opening end surface 2c of the cylinder body 1 is also chamfered over the entire circumference to form a tapered seal surface 2d. Further, a stopper cap 13 is fixed to the opening end of the cylinder hole of the cylinder body 1.

The stopper cap 13 has an opening 13c having a diameter such that a push rod can be loosely inserted in the central portion of the bottom plate 13a.
Is opened, and the cylindrical portion 13b is fitted to the outer circumference of the cylinder body 1, so that the outer edge portion of the inner surface of the bottom plate 13a is in contact with the end surface of the opening portion. The bottom plate 1 of the stopper cap 13
As shown in FIG. 3, an annular seal member 14 is provided on the inner surface side of 3a so as to project. The mounting position of the seal member 14 is a position where the sliding contact position between the inner peripheral surface of the cylinder hole 2 and the outer peripheral surface of the piston 3 opposes in the axial direction of the cylinder hole 2, that is,
It is set at a position where it can come into contact with the entire circumference of the inner peripheral side corner portion of the opening end of the cylinder hole 2 and the entire peripheral position of the end surface outer peripheral side corner portion of the primary piston 3.

Further, as shown in FIGS. 1 and 4, through holes 13d are formed in the bottom plate 13a along the mounting portion of the seal member 14, and the through holes 13d are formed in the through holes 13d. On the other hand, a mushroom-shaped protrusion protruding from the seal member 14 is fitted and attached from the inner peripheral surface side of the bottom plate 13a. A liquid passage 1a is provided in the cylinder body 1 and can communicate with a reserve tank (not shown) through the liquid passage 1a. Where 16
Is a hub for fixing the reserve tank.

In the master cylinder having the above structure, when the brake fluid is injected into the brake circuit at the time of assembling at the factory, there is a step of evacuating the circuit.
In this vacuum filling step, a high vacuum state is applied to the brake circuit, so that the primary piston 3 retracts and contacts the inner surface of the bottom plate 13a of the stopper cap 13.

Then, the seal surface 3a of the primary piston 3 comes into contact with the seal member 14 fixed to the bottom plate 13a. The seal member 14 is in contact with the seal surface 2d formed at the open end of the cylinder body 1 in advance by fixing the stopper cap 13 to the cylinder body 1. As a result, the seal member 14 seals between the primary piston 3 disposed on the open end side and the open end.

Therefore, in this embodiment, the secondary cup seal 12 provided on the primary piston 3 does not need to have a vacuum sealing property, and can be designed from the viewpoint of the original liquid tightness to the brake fluid. . After the above vacuum filling step, the brake fluid is filled in the brake circuit including the chamber formed in the cylinder hole 2.

After that, while the master cylinder is operating, the cup seals 9, 10, 1
1, 12 contribute to the liquid tightness of the chamber in the cylinder hole 2 defined by the piston 3, and the annular seal member 14
Becomes an unnecessary state. In addition, in the above embodiment, the protrusion 14a of the seal member 14 is assembled only by being fitted into the through hole 13d, but it may be fixed by a predetermined adhesive material.

However, it is easier to position the seal member 14 at the time of assembling as the above-mentioned construction in which the protruding portion 14a is fitted into the through hole 13d and attached.
It is easy to install and just fit. It should be noted that the attached seal member 14 is fixed in a state in which a part thereof is sandwiched between the bottom plate 13a and the end face of the opening of the cylinder body 1 when the stopper cap 13 is attached to the cylinder body 1, Further, since it is considered that a small force is not input to the seal member 14, the bottom plate 13a
It is not necessary to make the attachment of the seal member 14 to the rigid.

As shown in FIG. 5, the means for attaching the seal member 14 is the bottom plate 1 of the stopper cap 13.
An annular recess 13e is formed along the seal member 14 mounting portion on the inner surface of 3a, and a fitting portion that can be fitted into the recess 13e is provided on the back surface side of the seal member 14, and the fitting portion is The seal member 14 may be attached by being fitted into the ring-shaped recess 13e.

Also in this case, the positioning of the seal member 14 is easy and the mounting is easy. The recess 13e does not have to be formed in an annular shape along the mounting portion, and may be intermittently provided at a plurality of locations along the mounting portion. Next, a second embodiment will be described.

The master cylinder of the second embodiment is the same as the first cylinder described above.
This is an example of the case of a master cylinder having the same basic configuration as that of the embodiment and employing a disc-shaped stopper plate 17 instead of the stopper cap 13. That is,
As shown in FIG. 6, a stopper groove portion 1c formed along the circumferential direction is provided on the inner peripheral surface of the cylinder hole 2 on the opening end side, and a stopper plate 17 is attached to the stopper groove portion 1c. An annular seal member 14 is provided on the inner surface of the stopper plate 17 so as to project. The sealing member 14 is attached at a position where the inner peripheral surface of the cylinder hole 2 and the outer peripheral surface of the piston 3 are in sliding contact with each other in the axial direction of the cylinder hole 2, that is, the inner peripheral surface of the cylinder hole 2. It is set at a position where it can come into contact with the entire peripheral position of the end face outer peripheral side corner portion of the primary piston 3.

Further, through holes 17a are formed in the stopper plate 17 at a plurality of positions along the mounting portion of the seal member 14, and mushrooms projecting from the seal member 14 with respect to the through holes 17a. Protrusion 14
It is attached by inserting a from the inner surface side. The corner portion of the stopper groove 1c on the piston 3 side is chamfered to form a tapered seal surface, thereby increasing the contact area with the seal member 14 and improving the vacuum sealability.

The other structure, operation and effect are similar to those of the first embodiment. Although the tandem type master cylinder is described in all the above-mentioned embodiments, a single type master cylinder may be used.

[0036]

As described above, according to the first aspect of the invention, since the seal member secures the vacuum sealability when the brake fluid is filled in the master cylinder having the stopper cap, the cup seal is provided. There is no need to provide a vacuum sealability to the cup seal, and the cup seal can be designed only from the viewpoint of the original purpose of liquid tightness to the brake fluid and piston slidability, which has the effect of improving the degree of design freedom.

According to the second aspect of the present invention, since the seal member ensures the vacuum sealability when the brake fluid is filled, the cup seal has the vacuum sealability with respect to the master cylinder provided with the stopper plate. There is an effect that it is not necessary and can be designed only from the viewpoint of the cup seal, the liquid tightness to the original brake fluid, and the piston slidability, and the degree of freedom in design is improved.

Since the seal member does not come into sliding contact with the piston, it is not necessary to consider vibration during sliding, and it is necessary to contribute to the seal for liquid tightness when the master cylinder operates. There is no design flexibility. Further, in the structure described in claim 3, there is an effect that the positioning at the time of assembling the seal member becomes easy, and the seal member can be attached by a simple means of fitting into the recess. .

Further, in the structure described in claim 4, the positioning at the time of assembling the seal member is facilitated, and the seal member can be attached by a simple means of fitting the seal member into the through hole. . Further, when the configuration described in claim 5 is used, there is an effect that the contact area of the seal member is widened and the airtightness is improved.

[Brief description of drawings]

FIG. 1 is a partially enlarged side sectional view showing a stopper cap and a seal member in a master cylinder of a first embodiment according to the present invention.

FIG. 2 is a side sectional view showing a master cylinder of the first embodiment according to the present invention.

FIG. 3 is a front view of the stopper cap and the seal member according to the first embodiment of the present invention as viewed from the inner surface side.

FIG. 4 is a view of the stopper cap and the seal member of the first embodiment according to the present invention as seen from the outer surface side.

FIG. 5 is a partially enlarged side sectional view showing attachment of another seal member in the first embodiment according to the present invention.

FIG. 6 is a partially enlarged side sectional view showing a stopper cap and a seal member in a master cylinder of a second embodiment according to the present invention.

FIG. 7 is a partially enlarged side sectional view showing a stopper cap and a seal member in a conventional master cylinder.

FIG. 8 is a view showing a conventional cup seal.

[Explanation of symbols]

 1 Cylinder Main Body 1c Stopper Groove 2 Cylinder Hole 2d Sealing Surface 3 Piston 3a Sealing Surface 12 Cup Seal 13 Stopper Cap 13a Bottom Plate 13d Through Hole 13e Recess 14 Sealing Member 14a Projection 14b Fitting Part 17 Stopper Plate

Claims (5)

[Claims] 1. A piston is slidably disposed in a bottomed cylinder hole formed in a cylinder body, and a stopper cap is attached to an opening end of the cylinder hole so that an end surface of the piston is the stopper. In a master cylinder having a structure that restricts the movement of the piston toward the opening end by contacting the inner surface of the bottom plate of the cap, the inner peripheral surface of the cylinder hole and the outer peripheral surface of the piston on the inner surface of the bottom plate of the stopper cap. A master cylinder, characterized in that a seal member is provided so as to project over the entire circumference of a position that faces the sliding contact position of the cylinder hole in the axial direction of the cylinder hole. 2. A stopper, which is slidably disposed in a bottomed cylinder hole opened in the cylinder body, and which is a ring-shaped disc, on the inner peripheral surface of the cylinder hole on the opening end side. The plate is coaxially attached, and the end surface of the piston contacts the inner surface of the stopper plate,
In a master cylinder having a structure for restricting the movement of the piston toward the opening end, the sliding contact position between the inner peripheral surface of the cylinder hole and the outer peripheral surface of the piston on the inner surface of the stopper plate opposes in the axial direction of the cylinder. The master cylinder is characterized in that a seal member is provided so as to project over the entire circumference of the position. 3. A recess is provided in the inner surface of the bottom plate or the stopper plate along the entire circumference of the annular portion to which the seal member is attached or at a plurality of positions along the annular portion, and the seal member is provided with the inside of the recess. The master cylinder according to claim 1 or 2, further comprising a fitting portion that can be fitted into the master cylinder. 4. A through hole is provided at each of a plurality of positions on an inner surface of the bottom plate or the stopper plate along an annular portion to which the seal member is attached, and the seal member is provided with a protrusion that can be fitted into the through hole. The master cylinder according to claim 1 or 2, characterized in that. 5. A tapered seal surface by notching at least one of an inner peripheral corner portion of an opening end surface of a cylinder hole that can contact the seal member or an outer peripheral corner portion of a piston end surface that can contact the seal member. The master cylinder according to claim 1, wherein the master cylinder is provided with.