JP2002173015A - Piston cup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piston cup having good durability and not causing damage or cracks at the worst even in the case of use with a ring applied to the base surface. SOLUTION: This piston cup 20 is mounted on a piston 4 to seal between the piston 4 and a cylinder 2. The base surface 40 on the piston 4 side of the piston cup 20 is provided with a recessed part 42 for fitting the ring 41 supporting the piston cup 20, whereby the ring 41 is fitted in the recessed part 42 provided in the base surface 40 of the piston cup 20, so that a difference between the base surface 40 and the ring 41 surface is decreased to be almost flat, and rubbing of the peripheral edge part 41a of the ring 41 to the base surface 40 is decreased for that. Accordingly, abrasion or damage of the base surface 40 can be almost prevented to achieve the above object.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston cup having a recess for fitting a ring for supporting the piston cup on a base surface of the piston cup on the piston side.

[0002]

2. Description of the Related Art Various hydraulic devices are mounted on vehicles, especially automobiles. In these hydraulic devices, a piston cup is mounted on a piston to seal between the piston and the cylinder, and hydraulic oil is pressed by the piston and sent to various devices to operate them. On the other hand, liquid (hydraulic oil)
The hydraulic brake system that uses for transmitting power has many advantages such as excellent responsiveness, a simple structure, and a high degree of freedom in design, and is therefore used in most automobiles.
In this hydraulic brake system, from the viewpoint of safety, importance is attached to a piston cup for ensuring a sealing property between the piston and the cylinder. That is, if there is a problem in the sealing property of the piston cup, it means that even if the brake pedal is depressed, the force cannot be sufficiently transmitted to the hydraulic oil by the piston, and the hydraulic brake cannot be sufficiently operated. Therefore, the sealability of the piston cup is most important, and at the same time, its durability is also required.

As shown in FIG. 6, a conventional piston cup 50 slides on the inner peripheral surface of
A lip 53 for sealing between the cylinder and the cylinder 51 and a mounting portion 54 for mounting on the piston 52 are provided. A ring 56 smaller than the diameter of the piston cup 50 is applied to the base surface 55 of the piston cup 50, and the rigidity of the piston cup 50 is ensured.
Is designed to ensure its sealing properties.

[0004]

However, in the above-described piston cup 50, although a ring 56 having a smaller diameter is applied to the base surface 55, the rigidity is increased and the sealing performance is improved, but the piston cup 50 is used continuously. As a result, the peripheral edge 56a of the ring 56 comes into contact with the base surface 55, so that the ring 56 gradually wears and starts to be scratched, and finally there is a possibility that a rip may occur. When this breach occurs, hydraulic oil leaks from the breach, so that the hydraulic brake cannot be sufficiently operated, which may lead to a serious accident.

To prevent this, the material of the piston cup 50 is changed to a material which is hardly worn,
Although it is conceivable to add R (R) to 6a to make it hard to wear, it only lasts a little longer and does not become a fundamental solution. Therefore, the conventional piston cup 50 is
When used together with the ring 56, it is necessary to take measures such as regularly replacing the ring 56.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a piston cup which is excellent in durability without being damaged or worst-case tearing even when a ring is applied to a base surface. It is in.

[0007]

Means for Solving the Problems The present invention has been proposed to achieve the above object, and has the following structure. That is, according to the present invention, a piston cup mounted on a piston to seal between the piston and the cylinder, and a ring supporting the piston cup is provided on a base surface of the piston cup on the piston side. A piston cup provided with a concave portion for fitting is provided.

Further, according to the present invention, there is provided the above-described piston cup, wherein a ring-shaped groove is provided on a peripheral edge of a bottom surface of the concave portion of the base surface.

Further, according to the present invention, there is provided the above-mentioned piston cup, wherein a surface formed by the base surface and the ring surface is flat.

Further, according to the present invention, there is provided a piston cup mounted on a piston to seal between the piston and the cylinder, wherein a peripheral edge of a base surface of the piston cup on the piston side is cut off, A piston cup is provided, wherein a diameter of a ring supporting the piston cup is larger than a diameter of the base surface.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a master cylinder for a brake incorporating a piston cup according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of a piston cup according to an embodiment of the present invention and its periphery, and FIG. It is a top view of a piston cup showing an embodiment. In the figure, reference numeral 1 denotes a tandem-type master cylinder for brake. In this master cylinder for brake 1, first and second pistons 4 and 5 are slidably fitted in a bore 3 of the cylinder 2. . A first return spring 7 is mounted between one end of the first piston 4 and the bore bottom 6, and the first piston 4 is stopped at a set position by a stopper (not shown).

Similarly, a second return spring 8 is mounted between the other end of the first piston 4 and one end of the second piston 5, and the other end of the second piston 5 is fitted into the bore 9. The stop ring 10 is stopped at a set position. A first pressure cup 11 is fitted to the other end of the first piston 4, and the inside of the bore 3 of the cylinder 2 is divided into a region for the first piston 4 and a region for the second piston 5 in a liquid-tight manner. A second pressure cup 12 is provided at the other end of the second piston 5.
Is fitted, and the area of the second piston 5 and the atmosphere are shut off. The hole 13 on the other end side of the second piston 5
Is fitted with a push rod (not shown), and the push rod is connected to a brake pedal (not shown) via a booster or the like.

A first piston cup 20 is fitted to one end of the first piston 4. With the first piston cup 20 as a boundary, the area of the first piston 4 is divided into a first pressure chamber 21 and a first supply chamber 22. And liquid-tight. Similarly, a second piston cup 23 is fitted to one end of the second piston 5, and the area of the second piston 5 is divided by the second piston cup 23 into a second pressure chamber 24 and a second supply chamber 25. And liquid-tight. The first pressure chamber 21 and the first supply chamber 22 are separated by a hole 26 formed in the first piston 4.
Communication is made during the return process.

Similarly, the second pressure chamber 24 and the second supply chamber 25
The hole 27 is formed in the second piston 5 so as to communicate with each other during the return process. In addition, the first piston cup 20 is resiliently transmitted by the stopper 28, and the second piston cup 23 is resiliently transmitted by the stopper 29. The force prevents the first piston 4 and the second piston 5 from falling off during the return process.

Further, the cylinder 2 constituting the area of the first piston 4 is provided with a first reservoir 30 and a passage 31, and the first reservoir 30 has ports 32 and 33.
Thus, the first pressure chamber 21 and the first supply chamber 22 are connected to each other, and the passage 31 passes through a pipe (not shown) and is connected to, for example, a brake device or a clutch device. Similarly, the cylinder 2 forming the area of the second piston 5 has the second reservoir 3
4 and a passage 35 are provided.
Is connected to the second pressure chamber 24 and the first supply chamber 25 by ports 36 and 37, and the passage 35 passes through a conduit (not shown) like the passage 31, and is connected to, for example, a brake device or a clutch device.

The first and second piston cups 20 and 23 have exactly the same shape and function. Also, the first and second pressure cups 11 and 12
Has a different shape, but has almost the same action, and has almost the same action as the first and second piston cups 20 and 23 except that the pumping action described later is not performed.

Hereinafter, the first piston cup 20 (hereinafter simply referred to as the piston cup 20) will be described in detail. This piston cup 20 is mounted on the first piston 4 and
A ring 41 for supporting the piston cup 20 is provided on a base surface 40 on the first piston 4 side of the piston cup 20 for sealing between the piston 4 and the cylinder 2.
Is provided with a concave portion 42 for fitting therein.

That is, the piston cup 20 has a ring shape, and naturally has a lip portion 43 that slides on the inner peripheral surface of the bore 3 of the cylinder 2 to seal between the first piston 4 and the cylinder 2. And a mounting portion 44 for mounting to the first piston 4. The lip 43 requires not only a sealing action but also a pumping action.
In this pumping action, when the first piston 4 returns, the inside of the first pressurizing chamber 21 may have a negative pressure. In this case, the lip portion 43 bends into the bore 3 to supply hydraulic oil,
This allows the first piston 4 to return smoothly.

Therefore, the outer peripheral portion of the lip portion 43 is radially formed on the outer peripheral portion of the lip portion 43 so that the hydraulic oil is supplied even by a slight pumping action of the lip portion 43, that is, a slight bending.
A total of six grooves 45 are formed at every 0 degree, and these grooves 45 assist in replenishment of hydraulic oil. One end of the first piston 4 is fitted into the mounting portion 44.

On the other hand, the ring 41 is made of metal or resin, and is necessary to support both of the above-mentioned actions in the piston cup 20. This ring 41 is formed in a concave portion 42 provided in the base surface 40 of the piston cup 20. And the surface of the ring 41 and the base surface 40 are almost flat without any step. Therefore, even if the one end of the first piston 4 is fitted into the piston cup 20, the surface of the ring 41 and the base surface 40 abut equally on the step 4a formed by the large diameter portion and the medium diameter portion of the first piston 4. become. Therefore, the peripheral portion 41a of the ring 41 does not wear the base surface 40 and the concave portion 42 thereof due to the pressure from the first pressure chamber 21.

It is most ideal that the surface of the ring 41 and the base surface 40 are flat, but if the surface of the ring 41 is slightly sunk by the recess 42 below the thickness t of the ring 41,
As a result, the peripheral portion 41a of the ring 41 is less likely to wear the base surface 40 and the concave portion 42 thereof, which is also effective. Conversely, the surface of the ring 41 is
Even if it sinks below the base surface 40,
However, there is also an effect that wear of the base surface 40 is reduced. However, in this case, it is undeniable that the effect of the ring 41 for supporting both the above-described actions of the piston cup 20 slightly decreases. The ring 41 is a plate made of metal such as stainless steel or various hard resins. In order to prevent the piston cup from being scratched by the outer peripheral edge of the ring, the outer peripheral portion of the ring may be chamfered in an R shape or the like.

FIG. 4 shows another embodiment of the present invention. The difference between this piston cup 20a and the embodiment of FIGS. 2 and 3 is that a ring is formed on the periphery of the bottom surface 46 of the concave portion 42 of the base surface 40. Even if the sealing action and the pumping action by the lip portion 43 of the piston cup 20a are repeated, the peripheral edge portion 41a of the ring 41 has no contact with the ring-shaped groove 47.
2 is that there is no wear on the peripheral edge of the bottom surface 46. The other configuration and operation are the same as those of the embodiment of FIGS. 2 and 3, and therefore, the same reference numerals are given to the drawings, and the description thereof will be omitted. The base surface 4
Even when the ring-shaped groove 47 is provided directly on the base surface 40 without providing the concave portion 42 on the base 0, the base surface 40 is not worn and the generation of scratches and tears can be prevented.

FIG. 5 shows another embodiment of the present invention. The difference between this piston cup 20b and the embodiment of FIGS.
And the diameter R1 of the ring 41 is larger than the diameter R1 of the base surface 40.
2 is large, and the periphery 41 a of the ring 41 is
, So that the base surface 40 is not worn. Other components and operations are shown in FIG.
Since the third embodiment is the same as the third embodiment, the same reference numerals are given to the drawings and the description is omitted.

Next, the piston cup 2 having the above structure will be described.
The operation of 0, 20a and 20b will be described with reference to a tandem type brake master cylinder 1. FIG. 1 shows a state in which the brake master cylinder 1 is not operated. When the driver steps on the brake pedal from this state, the force is transmitted to the push rod via a booster or the like,
In FIG. 1, since the second piston 5 is pushed in the direction of arrow A and the first piston 4 is also pushed in the direction of arrow A, when the first and second piston cups 20 and 23 pass through the ports 32 and 36, the first piston And the second reservoirs 30 and 34 are shut off, the interiors of the first and second pressure chambers 21 and 24 are sealed and the pressure rises, and the hydraulic oil in these pressure chambers 21 and 24 flows from the passages 31 and 35 And then sent to, for example, a brake device, and thereafter, a braking action according to the brake pedal depression force is performed.

When the braking is released, the pressures in the first and second pressure chambers 21 and 24 and the spring forces of the first and second return springs 7 and 8 cause the first and second pistons 4 and 5 to move. It is returned in the direction of arrow B. At that time, a negative pressure is transiently generated in the first and second pressure chambers 21 and 24, but the first and second piston cups 20 and 23 are pressed by the first and second reservoirs 30 and 34. With the aid of the flexure and the aid of the groove 45, the hydraulic oil in the first and second supply chambers 22 and 25 passes through the holes 26 and 27 and quickly flows into the first and second pressure chambers 21 and 2.
The first and second pistons 4 and 5 are smoothly returned to the first piston 4 and the second piston 4. And the first and second
When the pistons 4 and 5 are further returned until the first and second piston cups 20 and 23 pass through the ports 32 and 36, the sealed state of the first and second pressure chambers 21 and 24 is released, and extra operation is performed. The oil returns to the first and second reservoirs 30 and 34, and the brake master cylinder 1 returns to the state of FIG.

Thus, each time the brake pedal is depressed, the first and second piston cups 20 and 23
Even if the sealing function and the pumping function are performed, the surface of the ring 41 and the base surface 40 are almost flat without any level difference, so that the step 4a formed by the large diameter portion and the medium diameter portion of the first and second pistons 4 and 5 and 5a will abut equally. For this reason, the first and second pressure chambers 21 and 24
The peripheral portion 41a of the ring 41 does not wear the base surface 40 and the concave portion 42 thereof due to the pressure from.
And, this corresponds to the piston cups 20a and 2 in FIG.
The same applies to 3a and the piston cups 20b and 23b in FIG.

Although the embodiment of the present invention has been described above, the specific configuration is not limited to this as long as the configuration requirements of the invention are satisfied.

[0028]

As described above in detail, according to the first aspect of the present invention, since the ring is fitted into the recess provided in the base surface of the piston cup, the corner of the peripheral edge of the ring rubs the base surface. And the base surface is hardly worn or scratched. Therefore, even if you apply the ring to the base surface and use it,
There is an effect that excellent durability can be obtained without occurrence of cracks.

According to the second aspect of the present invention, the ring-shaped groove prevents the corner of the peripheral edge of the ring from hitting anywhere on the base surface, does not rub, and wears and damages the base surface. Disappears. Therefore, the effect described in claim 1 can be further enhanced.

According to the third aspect of the present invention, since the surface formed by the base and the ring is flat, the peripheral edge of the ring hardly rubs the base surface, and the base surface is worn and scratched. Is almost eliminated. Therefore, also in this case, the effect described in claim 1 can be further enhanced.

According to the fourth aspect of the present invention, since the diameter of the ring is configured to be larger than the diameter of the base surface, the peripheral edge of the ring does not rub against the base surface, so that the base surface is worn and scratches are prevented. You will not be attached. Therefore, also in this case, the effect described in claim 1 can be further enhanced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a brake master cylinder in which a piston cup according to an embodiment of the present invention is incorporated.

FIG. 2 is a cross-sectional view of a piston cup and its periphery showing the embodiment of the present invention.

FIG. 3 is a plan view of a piston cup showing the embodiment of the present invention.

FIG. 4 is a cross-sectional view of a piston cup and its periphery showing another embodiment of the present invention.

FIG. 5 is a cross-sectional view of a piston cup and its periphery showing another embodiment of the present invention.

FIG. 6 is a sectional view showing a conventional example.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 master cylinder for brake 2, 51 cylinder 3 bore 4 first piston 4 a, 5 a step 5 second piston 6 bore bottom 7 first return spring 8 second return spring 9 bore opening 10 retaining ring 11 first pressure cup 12 second Pressure cup 13 hole 20, 20a, 20b, 50 First piston cup (piston cup) 21 First pressure chamber 22 First supply chamber 23, 23a, 23b Second piston cup (piston cup) 24 Second pressure chamber 25 Second Supply chambers 26, 27 holes 28, 29 Stop fittings 30 First reservoir 31, 35 Passage 32, 33, 36, 37 Port 34 Second reservoir 40, 55 Base surface 41, 56 Ring 41a, 56a Peripheral edge 42 Recess 43, 53 Lip part 44, 54 Mounting part 45 Groove 46 Bottom surface 47 Ring-shaped groove 48 Notch 2 the piston A, diameter t thickness of the diameter R2 ring B arrow R1 base surface

Claims (4)

[Claims] 1. A piston cup mounted on a piston for sealing between the piston and a cylinder, wherein a ring for supporting the piston cup is fitted on a base surface of the piston cup on the piston side. A piston cup characterized by having a concave portion. 2. The piston cup according to claim 1, wherein a ring-shaped groove is provided on a peripheral edge of a bottom surface of the concave portion of the base surface. 3. The piston cup according to claim 1, wherein a surface formed by the base surface and the ring surface is flat. 4. A piston cup mounted on a piston to seal between the piston and a cylinder, wherein a peripheral edge of a base surface of the piston cup on the piston side is cut away to reduce a diameter of the base surface. A piston cup, wherein a diameter of a ring supporting the piston cup is increased.