JPS6225963Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a structure for holding a cup seal provided on a master cylinder, particularly a piston.

Conventionally, in order to hold a ring-shaped cup seal that seals between a cylinder inner wall and a piston, a flange portion is provided on the outer periphery of the piston, and the cup seal is held in contact with the flange portion. The outer periphery of the flange has the function of slidingly contacting the inner wall of the cylinder and guiding the piston back and forth to prevent rattling of the piston. Oil holes are formed in this flange portion to facilitate the flow of oil.

However, according to the master cylinder having such a configuration, when the piston is reciprocated during air purge, etc., the cup seal is deformed by the hydraulic pressure, and a part of the cup seal deforms between the flange portion and the inner wall of the cylinder. It had the disadvantage that it could get bitten and become damaged.

Therefore, the outer diameter of the flange portion is made small, the gap between the flange portion and the cylinder wall is increased, and the cup seal is prevented from being bitten between them, and the sliding portion provided adjacent to the cup seal is The outside diameter of the cup seal is made larger than the flange part to guide the piston. According to this, when the cup seal falls forward due to the hydraulic pressure when the piston returns to its original position due to the force of the return spring. A part of the cup seal may get caught between the sliding part and the cylinder wall and break off, or a part of the cup seal may get stuck in the oil hole provided in the sliding part and become impossible to pull out, causing the cup seal to become damaged. This has the disadvantage that the seal cannot be restored to its original state, making it impossible to obtain a sealing effect.

The purpose of the present invention is to prevent the cup seal from falling forward by inserting a rod-shaped stopper into the oil hole provided in the sliding part and using the tip to eliminate the above-mentioned drawbacks. explain.

FIG. 1 is a sectional view of an embodiment of the present invention applied to a tandem master cylinder, and FIG. 2 is an enlarged view of the main part of FIG. 1.

In FIG. 1, a tandem master cylinder 1
The cylinder body 2 has a cylinder body 2.
A cylinder bore 3 is formed inside the cylinder bore 3, a first working piston 4 and a second working piston 5 are slidably inserted into the cylinder bore 3, a first hydraulic pressure generating chamber 6 is formed between the first working piston 4 and the second working piston 5, and
and an end wall 8 of the cylinder bore 3. A second hydraulic pressure generating chamber 7 is defined between the first hydraulic pressure generating chamber 6 and an end wall 8 of the cylinder bore 3. The first hydraulic pressure generating chamber 6 is connected to a front wheel cylinder (not shown), and the second hydraulic pressure generating chamber 7 is connected to a rear wheel cylinder (not shown).

Further, the first hydraulic pressure generating chamber 6 communicates with the reservoir 10 through a liquid return hole 9, and the second hydraulic pressure generating chamber 7 communicates with the reservoir 10 through a liquid return hole 11 through a liquid path 12.
communicate with. The reservoir 10 communicates with a liquid chamber 14 through a liquid supply hole 13 , and the liquid path 12 communicates with a liquid chamber 16 through a liquid supply hole 15 . 17 and 18 are piston return springs. The spring 17 includes a spring receiver 20 into which a bolt 19 screwed onto the first actuating piston 4 is loosely fitted, thereby limiting the maximum amount of movement;
Sliding part 21 formed at the front part of the first working piston 4
The spring 18 is stretched between the end wall 8 of the cylinder hole 3 and a sliding portion 22 formed at the front of the second working piston 5. The cup 31 attached to the rear of the first working piston 4 is connected to the liquid chamber 14.
The cup 32 attached to the rear part of the second actuating piston 5 prevents the liquid inside from leaking to the outside from the opening 30 of the cylinder hole 3, and the cup 32 installed at the rear of the second working piston 5 prevents the liquid from leaking to the outside from the opening 30 of the cylinder hole 3. Seal. The structures of the front portions of the first working piston 4 and the second working piston 5 are as shown in FIG. To explain the front part of the first working piston 4, the outer diameter of the sliding part 21 provided on the first working piston 4 is set to such an extent that the outer periphery 21a does not come into sliding contact with the inner wall of the cylinder hole 3 and cause play. This sliding part 21 has four oil holes 2.
1b is formed. A ring-shaped holding part 23 is formed on the outer circumferential side of the first working piston 4 via an annular cup seal groove 23b adjacent to this sliding part 21. This is set smaller than the diameter of the holding part 23.
The distance between the outer periphery 23a of the cylinder hole 3 and the inner wall of the cylinder hole 3 becomes larger, and the base part 24a of the cup seal part 24 becomes larger.
The oil will not get caught, and the oil can flow sufficiently through this gap. From both sides of the base portion 24a of the cup seal 24, there are lip portions 24b, 24.
c protrudes forward, and the base portion 24a is attached to the holding portion 23.
The outer lip portion 24b is in contact with the cylinder hole 3.
The inner lip portion 24c is fitted into the cup seal groove 23b, and the first actuating piston 4
surround the outer periphery of The oil hole 21b is shown in FIG.
As shown in FIGS. 4a and 4b, a rod-shaped stopper 25a that protrudes rearward passes through the ring body 25 located on the side of the first hydraulic pressure generating chamber 6.
The tip of 5a is the base part 24a of the cup seal 24.
The base portion 24a is extended to prevent the base portion 24a from falling forward. The ring body 25 is held and fixed at the front step portion 33 of the sliding portion 21 by the abutment surface 21c on the front side of the sliding portion 21 and the spring 17. A similar ring body 26, a stopper 26a, a cup seal 27, a holding part 28, a cup seal groove 2 also exist on the sliding part 22 side of the front part of the second working piston 5.
8b, contact surface 22c, spring 18, step portion 34
will be provided.

According to the above configuration, when the pistons 4 and 5 are reciprocated within the cylinder hole 3 during air purge, etc., the pistons 4 and 5 are guided by the sliding parts 21 and 22, so that the pistons 4 and 5 No rattling occurs. Also, since the clearance between the holding parts 23, 28 and the cylinder wall is large, when the pistons 4, 5 move forward, the base parts 24a,
27a is not caught between the two. Furthermore, when the pistons 4 and 5 return due to the pressing force of the springs 17 and 18, the oil pressure from the liquid chambers 14 and 16 causes the base portions 24a and 2 of the cup seals 24 and 27 to
Even if 7a and the lip part try to fall forward, the base parts 24a, 27a will stop the stoppers 25a, 26.
Since it is blocked at the tip of the lip part a, the lip part is not caught between the sliding part 21, 22 and the cylinder wall, or the lip part is not caught in the oil hole 21b, 22b.
It is possible to prevent the inconvenience that the lip portion 7 gets stuck and cannot be removed, and the cup seals 24, 27 do not return to the state shown in the figure. Furthermore, by making the oil hole 21b somewhat larger, the oil from the liquid chamber 14 side can be guided to the hydraulic pressure generation chamber 6 side through this oil hole 21b, and the hydraulic pressure generation chamber 6 can be prevented from becoming a vacuum. .
Moreover, since there is no need to separately provide a blocking plate to hold the cup seal 24, the number of parts is reduced.
Further, the ring body 25 is connected to the spring 17 and the sliding part 2.
I fixed it by sandwiching it between 1 and 1, so
There is no need for a separate fixing means for fixing the ring body 25, and the number of parts can be further reduced.

As explained above, according to the master cylinder according to the present invention, a piston is provided in the cylinder, and a holding part for holding a cup seal and a sliding part having a larger diameter than this holding part are provided on the outer periphery of the piston. A ring body is sandwiched between the sliding part and a return spring that presses the sliding part, and the deformation of the cup seal is transferred from the ring body to the cup seal side through the oil hole provided in the sliding part. The protruding restricting stopper part prevents the cup seal from falling forward in the direction of the sliding part, and reliably prevents the cup seal from being caught between the sliding part and the cylinder wall and by the oil holes provided in the sliding part. can. Particularly, according to the present invention, in the air bleed operation in which the hydraulic pressure generation chamber side is filled with hydraulic fluid by pumping the hydraulic fluid as shown in FIG. When the stopper 25a is pushed by the piston and a force in the opening direction is applied to the stopper 25a, the opening of the stopper 25a is restricted by the inner wall of the oil hole 21b. Therefore, as shown in the figure, there is a moderate gap between the inner lip 24c and the outer circumference of the piston. Provides a large gap, making it easy to pump hydraulic fluid and bleed air.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the master cylinder according to the present invention, FIG. 2 is an enlarged view of the main part of FIG. 1,
3, 4a and 4b, and 5 are enlarged front views and sectional views of the stopper shown in FIGS. 1 and 2. FIG. DESCRIPTION OF SYMBOLS 1... Tandem master cylinder, 3... Cylinder hole, 4... First working piston, 5... Second working piston, 9, 11... Liquid return hole, 17, 18...
...Spring, 21, 22...Sliding part, 25, 2
6...Ring body, 25a, 26a...Stopper.

Claims (1)

[Scope of utility model registration request] The inside of the cylinder is divided into a fluid pressure generating chamber 6 and a fluid chamber 14, and a piston 4 that slides inside the cylinder is provided. A sliding part 21 having an outer circumferential surface 21a on which the piston slides and a plurality of oil holes 21b communicating the hydraulic pressure generating chamber 6 and the liquid chamber 14; A ring-shaped base portion 24a that is fitted into the cup seal groove 23b and projects in the radial direction of the piston 4, and the sliding portion 21 from the inner and outer periphery of the base portion 24a.
A cup seal 24 having inner and outer lips 24c and 24b protruding in the direction, and a cup seal 24 formed on the outer periphery of the piston 4 so as to face the sliding portion 21 through the cup seal groove 23b, and holding the base portion 24a of the cup seal 24. A ring body 2 is provided along the outer circumference of the piston 4 between one end of the return spring 17 and the sliding part 21.
5, and the ring body 25 has an oil hole 21b passing through it, and the inner and outer lips 24c and 24c of the cup seal.
24b, a plurality of stopper portions 25a are formed that protrude toward the base portion 24a side.