JPH0421741Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a master cylinder used in vehicles and the like, and particularly to a type of master cylinder in which a cylinder hole sliding surface is formed of a cylindrical member.

[Conventional technology]

When making the cylinder body of the master cylinder by aluminum casting (pressure die casting),
In order to save the effort of finishing the sliding surface of the cylinder hole on which the piston slides and to increase productivity, a pipe-shaped cylindrical member is inserted into the inner hole of the cylinder body and the inside of the cylindrical member is used as the cylinder hole to hold the piston. In some cases, it may be made to slide. Furthermore, when the cylinder body is made of plastic material, the cylindrical member is also used as a reinforcing material.

In a master cylinder having this type of structure, the discharge part of the pressurized fluid (working fluid) pressurized in the pressure chamber is formed on the side of the cylinder body, so that the outer periphery of the cylindrical member is a cylindrical surface. Therefore, there were problems from the sealing surface, and conventionally, for example,
As seen in Publication No. 57263, the discharge part is provided at the end of the cylinder body, but in the case of a tandem master cylinder, even if the discharge part of one pressure chamber is formed at the end, the discharge part of the other pressure chamber is The discharge part must necessarily be formed on the side, and the above-mentioned sealing problem remains unsolved.

The present invention was made to solve the above problems, and provides a master cylinder that can ensure sealing and form a discharge part on the side even when the sliding surface of the cylinder hole is formed of a cylindrical member. The purpose is to

[Means for solving problems]

In order to achieve the above object, the present invention forms a pair of outward protrusions on the cylindrical member to be inserted into the inner hole of the cylinder body, and arranges a pair of sealing members between the two protrusions to partition the space. The discharge part provided for the main pressure chamber is configured to communicate with the main pressure chamber via the space.

[Effect]

In the present invention, an outward protrusion is formed at an appropriate position in the length direction of the cylinder member, and a cavity is formed between both protrusions and the circumferential surface of the inner hole of the cylinder body by sealing with a sealing member. is communicated with the main pressure chamber through a hole formed in the cylindrical member, and the discharge hole of the cylinder body is opened toward the cavity, so the seal structure that partitions the cavity may be a normal seal structure; The area can be reliably sealed from others.

〔Example〕

An embodiment of this invention will be described below with reference to the drawings.

In Fig. 1, reference numeral 1 denotes the cylinder body of a tandem master cylinder, which is made of aluminum casting. , two bosses 4 and 5 for connecting the hydraulic fluid reservoir 3
are formed to protrude at a predetermined interval in the longitudinal direction, and boss portions 6 and 7, which serve as discharge portions, are formed to protrude from the front end (left end in the figure) and the lower part of the outer periphery, respectively.

The inner hole 2 is a stepped hole, and consists of a small diameter portion 9, which is approximately half the diameter on the bottom wall 8 side, and a large diameter portion 11, which is the remaining half on the opening 10 side, and the cylindrical member 12 is inserted from the opening 10 side. Thus, a cylinder hole 13 is formed. This cylindrical member 12 has a bottom wall 8 having a central recess 8A of the inner hole 2.
The leading end of the cylindrical member 12 fits into the circumferential groove 14 formed around the bottom wall 8, and the rear end
It is internally fitted into the fitting part 15A of the presser foot 15 of the mouth device which is tightly fitted into the inner hole 2 from the opening 10 side. This mouth device includes the presser foot 15 and the presser foot 15.
It has a sealing member 16A adjacent to the opening 10 side and a back opening 16B, and is prevented from coming out by a retainer 17. This presser foot 15 has the above-mentioned fitting portion 15A and a liquid passage 15B.

The cylindrical member 12 is shaped like a pipe and has an outer diameter that is the same as the inner diameter of the small diameter part 9 of the inner hole 2, has an inner surface suitable for sliding, and has an outer diameter in the center part that is the same as the inner diameter of the large diameter part 11. Outwardly directed circumferential protrusions 18 and 19, which are the same as the circumferential protrusions 18, are formed at a small distance apart, and sealing members 20 and 21 are provided at the portions separating the small distances from the circumferential protrusions 18, respectively.
and 19 are fitted adjacent to each other. This cylinder member 1
2 is a fitting part 1 which is closed with a circumferential protrusion 19 at one end and a presser foot 15 at the other end, between the inner surface of the large diameter part 11 of the inner hole 2.
5A defines a cylindrical liquid supply path 22 partially closed, and also defines a cavity 23 that is tightly closed on both sides by sealing members 20 and 21 and communicates with the discharge hole 7A of the discharge part 7. A discharge port 24 communicating between the space 23 and the cylinder hole 13 is provided at the small interval.
is formed. The liquid supply path 22 communicates with the hole 47 of the boss portion 5.

A slave piston 25 is slidably inserted into the cylinder hole 13 on the bottom wall 8 side forward of the circumferential projection 18 with a return spring 26 interposed between it and the bottom wall 8, and on the opening 10 side. , a main piston 28 connected to a slave piston 25 via a caged spring device 27
is slidably inserted. The return spring 26 is a deep dish-shaped spring receiver 29 that fits into the recess 8A of the bottom wall 8.
and a recess formed in the front end surface of the slave piston 25. The caged spring device 27 passes through a retainer 30 attached to the rear end surface of the slave piston 25, a spring receiver 31 that loosely passes through the retainer 30 and engages with the front end surface of the main piston 28, and is screwed into the front end surface. It consists of a bolt 32 and a return spring 33.

The slave piston 25 has a small diameter part that defines a liquid replenishment chamber 34 between it and the inner circumferential surface of the cylinder hole 13, and has a small diameter part between the bottom wall 8 and the front end where the lip seal 35 is fitted. Subpressure chamber 3 communicating with discharge hole 6A
6, the main piston 28 has a front end fitted with a lip seal 37, and a lip seal 38.
A main pressure chamber 39 is defined between the slave piston 25 and the rear end of the slave piston 25 fitted therein, and a liquid replenishment chamber 40 is formed between the presser foot 15 and the sealing member 16.
A, it passes through the back upper part 16B tightly and slidably and projects to the outside. The liquid replenishment chamber 34 and the pressure dependent chamber 36 are formed through a through hole 41A and a loosening hole 41B formed in the cylinder member 12, respectively, and a hole 4 in the cylinder wall.
The main pressure chamber 39 communicates with the liquid supply path 22 through the loosening hole 43 formed in the cylinder member 12, and the liquid supply chamber 40 communicates with the liquid supply path 22 through the liquid passage 15B. It is connected to 22.
The liquid supply path 22 communicates with the inner hole 47 of the boss portion 5 through a hole 44 in the cylinder wall.

Two connecting portions 45, 45 having a liquid passage 45A protrude downward from the bottom of the main body 3A of the hydraulic fluid reservoir 3;
45 into the boss portions 4 and 5 to remove the cylinder body 1.
It is assembled into. A small projection 46 for engagement is formed in the connecting portions 45, 45 at approximately the middle position in the height direction. Holes 47 in boss parts 4 and 5
is a stepped hole having a large-diameter hole 48 on the upper end side and a medium-diameter hole 49 on the inner hole 2 side, and the large-diameter hole 48 further has an upper half and a lower half with slightly different diameters. ing.

When assembling the hydraulic fluid reservoir 3 to the cylinder body 1, insert the large diameter hole 48 of the hole 47 of the boss portion 4 into the
A sealing member 50 having the cross-sectional shape shown in FIG.
Press fit inside. Since the connecting parts 45, 45 have small protrusions 46, the small protrusions 46 catch on the annular member 52 during the press-fitting. 45 while elastically deforming it. 53 is a lid of the hydraulic fluid reservoir 3, 54 is a diaphragm, 55 is a float with a magnet, and 56 is a reed switch assembly.

Next, the operation of this master cylinder will be briefly explained.

FIG. 1 shows a state in which the brake pedal is not operated, and the slave pressure chamber 36, fluid replenishment chamber 34, fluid replenishment path 22, main pressure chamber 39, and fluid replenishment chamber 40 are filled with hydraulic fluid at normal pressure. The lip seals 38 and 37 face a position slightly rearward from the loosening holes 41B and 43.

By depressing the brake pedal (not shown),
When the push rod (not shown) connected to the main piston 28 is pushed to the left in the figure, the slave piston 25 and the main piston 28 move in the same direction, and when the lip seal 38 passes through the loosening hole 41B, it is inside the slave pressure chamber 36. A liquid pressure is generated, and the liquid pressure is discharged from the discharge hole 6.
It is supplied from A to the brake device through a pipe (not shown). On the other hand, the lip seal 37 is inserted into the loosening hole 4.
3, hydraulic pressure is generated in the main pressure chamber 39,
The liquid pressure is transmitted from the discharge port 24 through the cavity 23 to the discharge hole 7.
A and is supplied to the brake device through a pipe (not shown).

In this embodiment, a pair of circumferential protrusions 18 and 19 are formed in parallel on the outer circumference of the cylindrical member 12 and have a height that almost reaches the circumferential surface of the inner hole 2 of the cylinder body 1. An annular space is defined therebetween, and a sealing member 20 seals between the circumferential protrusion 18 and the circumferential surface of the inner hole 2, and a sealing member 21 seals between the circumferential protrusion 19 and the circumferential surface of the inner hole 2. A space 23 is defined between both sealing members 20 and 21, and a discharge hole 7A is opened to this space 23. Since this structure is sufficient, it is possible to reliably prevent the hydraulic pressure from the main pressure chamber 39 from leaking to the liquid supply path 22 side, for example.

Note that the present invention is also applicable to cases where the cylinder body is made of plastic material.

[Effect of idea]

As explained above, in the present invention, a sealing member is fitted to a cylinder member at a certain interval to define an annular space between the sealing member and the inner peripheral surface of the inner hole of the cylinder body, and the discharge hole is connected to this space. Since the discharge part of the main pressure chamber that opens into the cavity is formed on the side of the cylinder body, even though the discharge part is on the side of the cylinder body, the liquid pressure from the main pressure chamber divided within the cylindrical member can be It can be guided to the discharge part without escaping out of the space, and although it has a simple sealing structure, it can reliably seal the passage of hydraulic pressure from the main pressure chamber to the discharge part.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, and FIG. 2 is a sectional view of a sealing member in the above embodiment. 1...Cylinder body, 2...Inner hole, 6A, 7A
...Discharge hole, 8...Bottom wall, 12...Cylinder member, 1
8, 19... Circumferential projection, 20, 21... Sealing member,
23...Vacancy, 25...Slave piston, 28...Main piston, 36...Slave pressure chamber, 39...Main pressure chamber.

Claims (1)

[Scope of utility model registration request] A cylinder body molded with an inner hole formed, a pipe-shaped cylindrical member inserted into the inner hole, a main piston and a slave piston slidably inserted into the cylinder member, and a main piston and a slave piston. A master cylinder having a main pressure chamber partitioned between a main pressure chamber, a sub-pressure chamber partitioned between the sub-piston and the bottom of the inner hole, and a discharge part provided for each of the main pressure chamber and the sub-pressure chamber, The discharge section provided for the main pressure chamber is communicated with the pressure chamber through a space partitioned by a pair of sealing members arranged between a pair of outward protrusions formed on the cylindrical member. master cylinder.