JPS6312029Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a master cylinder for a vehicle brake equipped with a negative pressure booster.

[Prior Art] As shown in the main part of this type of master cylinder in FIG. 1, an enlarged diameter portion 1b is formed at the open end of the cylinder hole 1a of the master cylinder 1 that is connected to a negative pressure booster. , two outer circumferential grooves 2a, 2a and two inner circumferential grooves 2b, 2b are respectively formed in the enlarged diameter portion 1b, and O-rings 2c, 2c are respectively formed on the inner circumference of the outer circumferential walls 2a, 2a. Cup seals 2d, 2d are fitted into the grooves 2b, 2b, respectively, and
A ring-shaped bearing member 2 is fitted between the two inner circumferential grooves 2b, 2b and between the two outer circumferential grooves 2a, 2a, forming a liquid passage 2e that communicates the inner circumferential side and the outer circumferential side, It is prevented from coming off by the circlip 3, and the piston rod part 4 is movably sealed by the inner periphery of the bearing member 2, and the liquid of the bearing member 2 is discharged into the discharge hole 1c bored in the lower part of the circumferential wall of the enlarged diameter part 1b of the cylinder hole 1a. The passage 2e is communicated with the hydraulic fluid leaked from the cylinder hole 1a between the inner cup seals 2d of the piston rod portion 4, and the hydraulic fluid leaked from the cylinder hole 1a is discharged to the outside. A master cylinder equipped with a bearing member 2 having a double seal structure to prevent intrusion into the cylinder (not shown) has been known, but a master cylinder equipped with a bearing member having the above structure has a ring-shaped bearing member. Two inner circumferential grooves for fitting the cup seals were cut on the inner circumferential surface of the cup, and the cup seals were fitted into the inner circumferential grooves.

When assembling the bearing member, each with a cup seal fitted into the inner circumferential groove, into the enlarged diameter part of the cylinder hole, it is difficult to insert the piston rod part because the lip parts of the two cup seals protrude. There is a risk that the cup seal will get caught between the inner peripheral surface of the bearing and the piston rod and be damaged. Furthermore, the assembly position is restricted because the liquid passage bored in the bearing member must be aligned with the position of the discharge hole bored in the lower part of the outer wall of the enlarged diameter portion of the cylinder hole.

[Purpose of the invention] The present invention was devised in view of the above points, and it reliably prevents liquid leaking from the cylinder hole from entering the negative pressure booster, and is easy to assemble.
Moreover, it is an object of the present invention to provide a master cylinder equipped with a bearing member that causes less damage to the cup seal during assembly.

[Structure of the invention] In order to achieve the above purpose, in this invention,
A cylinder body is joined to a booster shell of a negative pressure booster, a piston is fluid-tightly and movably fitted into a cylinder hole of the cylinder body, and a piston rod portion of the piston is fitted into the rear end of the cylinder hole. In a master cylinder that is slidably supported by a bearing member and has the piston rod section connected to an outlet rod in the booster shell, the bearing member has an insertion hole for the piston rod section in the center of the disk and a peripheral hole for the piston rod section on the outer periphery. a groove, a plurality of radial drainage grooves on one side of the disk, and an enlarged diameter stepped portion on the periphery of the insertion hole on the other side, and a sealing member is provided in the circumferential groove and the enlarged diameter stepped portion, respectively. The bearing member is fitted in a continuous manner to the rear end of the cylinder hole, and is pressed and fixed to the front of the cylinder by a locking member having a spring force.

[Embodiment] Next, an embodiment of the present invention will be described based on FIGS. 2 to 4.

A cup seal 11a is provided on the rear open side of the series of cylinder holes 10a of the tandem type master cylinder 10.
A first hydraulic pressure chamber 10b is provided in front of the first piston 11 by the first piston 11 which is fitted in a fluid-tight and movable manner, and a second piston 12 is provided in front of the first hydraulic pressure chamber 10b with a cup seal 12a, 12a, the cylinder hole 10 is fitted liquid-tightly and movably.
A second hydraulic pressure chamber 10c is defined between the ends of the first piston 11, and a return spring 13a is compressed at the front portion of the first piston 11. Further, a return spring 13b is compressed between the front end of the second piston 12 and the tip of the cylinder hole 10a.

On the other hand, a mounting boss part 14 for a reservoir (not shown) is integrally formed in the upper part of the cylinder hole 10a, and a first liquid reservoir chamber 14 is provided in the mounting boss part 14.
a and a second liquid reservoir chamber 14b are formed, and the first liquid reservoir chamber 14a and the first hydraulic pressure chamber 10b are connected to a liquid passage 15.
via relief port 16 and supply port 1
7, and the second liquid reservoir chamber 14b and the second hydraulic pressure chamber 10c are communicated through a relief port 18 and a supply port 19.

Further, behind the first piston 11, the first
A piston rod portion 11b of the piston 11 is extended, and the rear end of the piston rod portion 11b is connected to an enlarged diameter portion 10 formed at the open end of the cylinder hole 10a.
booster shell 2 on the output side of the negative pressure booster 21 airtightly joined to the outside of d by a sealing material 20;
A fitting hole 11c for an output rod (not shown) of the negative pressure booster 21 is formed in the end surface of the piston rod portion 11b.

In the enlarged diameter portion 10d formed at the open end of the cylinder hole 10a, there is a bearing member 22 that liquid-tightly seals the outer periphery of the piston rod portion 11b and guides the movement of the piston rod portion 11b in the axial direction. , 22 are fitted.

The bearing member is composed of a bearing member 22 having the same structure, and the piston rod portion 11 is located at the center of the bearing member 22.
Four radial drain grooves 22c are formed equally spaced on one side of the disk, which has an insertion hole 22a through which the hole 22b is inserted, and a circumferential groove 22b formed approximately in the center of the outer peripheral surface. On the other side, a circumferential step 22d is formed by enlarging the diameter of the opening of the insertion hole 22a, and an O-ring 23 is fitted into the circumferential groove 23b, and a cup seal 24 is fitted into the circumferential step 22d. Then, the surfaces of the bearing members 22, 22 on which the drain grooves 22c are formed face the open side of the enlarged diameter portion 10d, and the piston rod portions 11b are inserted into the respective insertion holes 22a, 22a, so that they are overlapped. It is fitted into the enlarged diameter portion 10d in this state.

Further, the front surface of the front bearing member 22 is connected to the enlarged diameter portion 1.
Piston stopper plate 2 located within 0d
5, and the rear surface of the rear bearing member 22 is the enlarged diameter portion 1
It abuts against a spring-like circlip 26 attached to a groove 10e formed at the open end of 0d, and is pressed and fixed to the front of the cylinder.

Further, between the bearing members 22, 22, the four drainage grooves of the front bearing member 22 are formed radially, and the chamfered portions of the outer peripheral corners of both bearing members 22, 22 are opposed to each other, and the diameter is expanded. A circumferential gap 27 having a triangular cross section is formed on the inner peripheral surface of the portion 10d, and communicates with the four drain grooves 22c on the outer peripheral side of the bearing member 22.

Further, a discharge hole 28 penetrating to the outside is bored in the lower part of the enlarged diameter portion 10d, and the discharge hole 28
One end is open facing the circumferential gap 27.

The tandem master cylinder 10 configured as described above has an output rod (not shown) that outputs an operating force doubled by the action of a negative pressure booster 21 activated by a braking operation such as a brake pedal (not shown). ), the piston rod portion 11b of the first piston 11 is pushed in the braking direction, and the first piston 11 and the second piston 12 are moved into the cylinder hole 10.
move forward in the inside of the first hydraulic pressure chamber 10b and the second hydraulic pressure chamber 10b.
The pressure inside the hydraulic pressure chambers 10c is increased, and pressurized fluid is supplied to front and rear wheel cylinders (not shown) from discharge ports (not shown) opening into each hydraulic pressure chamber to perform a braking action.

Further, the cup seal 24 fitted to each bearing member 22 comes into contact with the outer circumferential surface of the piston rod portion 11b to prevent leakage of hydraulic fluid from the inside of the cylinder hole 10a. Even if a small amount of hydraulic fluid adhering to the surface of 11b passes through the front cup seal 24, it is scraped off by the rear cup seal 24 and drains into the drain groove 2.
2c and is discharged to the outside from the discharge hole 28.
Further, even if the outer circumferential end of the drain groove 22c does not directly communicate with the drain hole 28, the liquid can be drained from the drain hole 28 via the circumferential gap 27. Furthermore, the hydraulic fluid leaked from the front O-ring 23 that seals the outer peripheral surface of the bearing member 22 also flows into the circumferential gap 2.
7 to the outside from the discharge hole 28 to prevent leaked hydraulic fluid from entering the load type booster 21.

Further, the circlip 26 that presses the bearing member 22 forward and fixes it is attached to both the bearing members 22, 22.
and the bearing member 22 and the piston stopper plate 25 are brought into contact and fixed without any gap, and
The piston stopper plate 25 is inserted into the cylinder hole 10.
The rear end of the first piston 11 is press-fixed to the front step inside the enlarged diameter section 10d to position the backward limit of the first piston 11, thereby eliminating back and forth movement of the bearing member 22 within the enlarged diameter section 10d.

[Effects of the invention] As described above, the present invention has an insertion hole for the piston rod in the center of the disc, a circumferential groove on the outer periphery, and
A plurality of radial drainage grooves are formed on one side of the disk, and an enlarged diameter step is formed on the periphery of the insertion hole on the other side, and a sealing member is fitted into the circumferential groove and the enlarged diameter step, respectively. Since the bearing members are constructed by overlapping the bearing members and fitted together, a drainage path is definitely formed between the bearing members, and the hydraulic fluid leaked from the cylinder hole side is reliably discharged to the outside, and the piston rod portion is It is possible to prevent liquid leakage from entering the negative pressure booster.

Further, since the bearing members of the same structure are stacked one on top of the other, one bearing member can be installed in the rear end of the cylinder hole, making assembly easy and preventing damage to the cup seal.

Furthermore, since the bearing member is pressed forward and fixed to the rear end of the cylinder hole by a locking tool having a spring force, there is no movement of the bearing member during braking operation, and no gaps are created between the bearing members.
It has the effect of preventing damage to the cup seal due to biting.

[Brief explanation of the drawing]

Fig. 1 is a sectional front view of main parts of a conventional master cylinder, Figs. 2 to 4 show an embodiment of the present invention, and Fig. 2 is a partially cutaway sectional front view of the master cylinder, Figure 3 is an enlarged sectional view of the main part of Figure 2.
FIG. 4 is a perspective view of a bearing member used in the present invention. 10 is a tandem type master cylinder, 10a is a cylinder hole, 10d is an enlarged diameter portion, 11 is a first piston, 11b is a piston rod portion, 12 is a second piston, 21 is a negative pressure booster, 21a is a booster shell, 22 is a Bearing member, 22a is an insertion hole, 22
b is a circumferential groove, 22c is a drainage groove, 22d is a circumferential step,
23 is an O-ring, 24 is a cup seal, 25 is a piston stopper plate, 26 is a circlip,
27 is a circumferential gap, and 28 is a discharge hole.

Claims (1)

[Scope of utility model registration request] A cylinder body is joined to a booster shell of a negative pressure booster, a piston is fluid-tightly and movably fitted into a cylinder hole of the cylinder body, and a piston rod portion of the piston is fitted into the rear end of the cylinder hole. While being slidably supported by a bearing member,
In the master cylinder in which the piston rod portion is connected to the output rod in the booster shell, the bearing member has an insertion hole for the piston rod portion in the center of the disk, a circumferential groove on the outer periphery, and a plurality of radii on one surface of the disk. A drain groove in the direction is formed, and an enlarged-diameter step is formed on the periphery of the insertion hole on the other side, and a seal member is fitted into the circumferential groove and the enlarged-diameter step, respectively, and the bearing member is connected to the cylinder. Continuously fitted at the rear end of the hole,
What is claimed is: 1. A master cylinder, characterized in that the master cylinder is pressed and fixed to the front part of the cylinder by a locking tool having a spring force.