JP2002174345A - Piston cup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piston cup having a flow groove and excellent durability and capable of preventing the occurrence of a crack at the worst time when it is broken and damaged even if used by applying a ring to a base face. SOLUTION: This piston cup 20 is mounted on a piston 4 to seal between the piston 4 and a cylinder 2 and includes the flow groove 42 in which operating liquid passes in an outer peripheral part 43. A built-up part 44 is provided on the back side of the outer peripheral part 43 in which the flow groove 42 is positioned to replenish a thin-walled part by the flow groove 42 so that the flow groove 42 is not swelled and is not broken because stress is not concentrated owing to the built-up part 44. Consequently, this piston cup has excellent durability even if it has the flow groove 42.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston cup provided with a built-up portion on the back side of an outer peripheral portion provided with a flow groove through which a hydraulic fluid passes, and replenishing a thin portion generated by the flow groove.

[0002]

2. Description of the Related Art Various hydraulic devices are mounted on vehicles, especially automobiles. These hydraulic devices attach a piston cup to a piston, seal between the piston and the cylinder, circulate hydraulic oil, press the hydraulic oil with the piston, send it to various devices and return it, To operate. On the other hand, hydraulic brake systems that use liquid (hydraulic oil) for power transmission have many advantages such as excellent responsiveness, simple structure, and high degree of design freedom. I have. In this hydraulic brake system, from the viewpoint of safety, a piston cup that secures sealability and flowability between the piston and the cylinder is regarded as important.

[0003] If there is a problem with the sealability of the piston cup, it means that even when 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. On the other hand, if there is a problem with the flowability, it means that even if the brake pedal is released, the piston does not return smoothly and the hydraulic brake is not released sufficiently. Therefore,
The piston cup is important not only for its sealing property but also its flowability, and is also required to have durability.

As shown in FIG. 7, 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. 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 sufficiently secured. On the other hand, at the boundary between the lip portion 53 and the base surface 55, a flow groove 57 is formed.
Is provided, and its circulation is ensured.

[0005]

However, the above-described piston cup 50 has a lip portion 53 and a base surface 55.
A flow groove 57 is provided at the boundary between the grooves, which contributes to the flow and enhances the flowability. However, the portion where the flow groove 57 is provided becomes thinner, and the stress concentrates on the thinner portion and swells. It is easy to break. Further, there is a problem that the peripheral portion 56a of the ring 56 comes into contact with the base surface 55 due to continuous use, and the ring 56 starts to be worn and scratched, and finally a tear is generated.

[0006] As described above, if these thin portions are damaged or broken, hydraulic oil leaks therefrom, and the hydraulic brake cannot be operated sufficiently, which may lead to a serious accident. . To prevent this, it is conceivable to change the material of the piston cup 50 to a tough or hard-to-wear material, or to add R (R) to the peripheral edge 56a of the ring 56 to make it hard to wear. Just taking action will only last a little longer and will not be a fundamental solution. Therefore, the conventional piston cup 50 needs to be replaced regularly, for example.

[0007] Therefore, an object of the present invention is to provide a thin wall portion associated with a flow groove, and even if a ring is applied to the base surface, it may be damaged or damaged, and a crack may occur at worst. Instead, to provide a piston cup with excellent durability.

[0008]

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, the piston cup is mounted on a piston to seal between the piston and the cylinder, and has a flow groove on the outer peripheral portion through which the hydraulic fluid passes, wherein the flow groove is provided. A piston cup is provided, wherein a built-up portion is provided on the back side of the outer peripheral portion, and a thin portion generated by the flow groove is supplemented.

Further, according to the present invention, the overlay is
The above-mentioned piston cup formed to have a size corresponding to at least the flow groove is provided.

Further, according to the present invention, there is provided the above-mentioned piston cup in which the flow groove is provided with R (R) at a boundary between the flow groove and the outer peripheral portion.

According to the present invention, a ring-shaped groove is provided in a base surface formed on a piston side of the piston cup according to any one of claims 1 to 3, and a peripheral edge of a ring supporting the piston cup. A piston cup is provided, wherein a portion is located in the ring-shaped groove so that the peripheral portion does not abut on the base surface.

[0012]

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 in which a piston cup according to an embodiment of the present invention is incorporated, FIG. 2 is a cross-sectional view of the piston cup according to the 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 wheel 10 stops 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 liquid-tight region into a first piston 4 region and a second piston 5 region. I have. The second pressure cup 12 is fitted to the other end of the second piston 5 to block the area of the second piston 5 from the atmosphere. A hole 13 at the other end 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. are doing.

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 on one end side 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. Similarly, 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. The first reservoir 30 is connected to the first pressure chamber 21 and the first supply chamber by ports 32 and 33. Connected to 22,
The passage 31 passes through a pipe (not shown) and is connected to, for example, a brake device or a clutch device. Similarly, the second piston 5
A second reservoir 34 and a passage 35 are provided in the cylinder 2 constituting the region of the second pressure chamber 24. The second reservoir 34 is connected to the second pressure chamber 24 and the first supply chamber 25 by ports 36 and 37. The passage 35 passes through a conduit (not shown) similarly to 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.

Next, 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 seal is provided between the piston 4 and the cylinder 2, and between the first piston 4 and a base surface 40 formed on the first piston 4 side of the piston cup 20.
And a flow groove 42 through which the hydraulic fluid passes is included in an outer peripheral portion 43 of the outer peripheral portion 43 provided with the flow groove 42. The thin portion caused by the groove 42 is supplemented.

The built-up portion 44 is formed to supplement the thinning of the portion by the flow groove 42 formed on the front surface side, so that at least the size of the flow groove ( (Equivalent to the volume) is preferably replenished.

The piston cup 20 has a ring shape and naturally slides on the inner peripheral surface of the bore 3 of the cylinder 2 to seal the lip 45 between the first piston 4 and the cylinder 2.
Mounting portion 4 for mounting on the first piston 4
6, and one end of the first piston 4 is fitted into the mounting portion 46. The lip 45 requires not only a sealing action but also a pumping action. This pumping action is performed by the first piston 4 during the return process.
In some cases, the pressure inside the pressurizing chamber 21 becomes a negative pressure. In this case, the lip portion 45 bends toward the inside of the bore 3 so that the working oil is replenished so that the first piston 4 can return smoothly.

Therefore, the outer peripheral portion 43 of the piston cup 20 is provided so that the hydraulic oil is supplied even with a slight pumping action of the lip portion 45, that is, a slight bending.
To be precise, a total of six flow grooves 42 described above are engraved radially at every 60 degrees at the boundary between the lip portion 45 and the base surface 40, and these flow grooves 42 help replenish the hydraulic oil. . The thin portion caused by the engraving of the flow groove 42 is replenished by the overlaid portion 44, thereby preventing breakage. Further, as shown in FIGS. 4 and 5, durability is increased by adding R (R) to corner portions of the flow groove 42 as shown in FIGS.

On the other hand, the ring 41 is necessary to support both the above-mentioned actions in the piston cup 20,
The ring 41 is provided in close contact with the base surface 40 of the piston cup 20. This ring 41 is fitted with one end of the first piston 4 together with the piston cup 20,
Only the surface of the ring 41 comes into contact with the step 4a formed by the large diameter portion and the medium diameter portion of the first piston 4. Therefore, the first
Due to the pressure from the pressure chamber 21, the peripheral portion 41 of the ring 41
The ring-shaped groove 47 is provided on the base surface 40 as shown in FIG. 6 because the a contacts the base surface 40 and causes abrasion, causing damage or worst case tears. Therefore, the peripheral portion 41 a of the ring 41 is
Accordingly, the contact with the base surface 40 is prevented, and the base surface 40 is not worn. The rings 41 and 56 are formed from a plate material such as a metal such as stainless steel or a hard resin. Further, in order to prevent the piston cup from being scratched by the outer peripheral edge portion of the ring, the outer peripheral portion of the ring may be chamfered in an R shape or the like.

Next, the piston cup 20 having the above structure will be described.
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, and the second in FIG. Piston 5
Is pushed in the direction of arrow A, and the first piston 4 is also pushed in the direction of arrow A. Therefore, when the first and second piston cups 20 and 23 pass through the ports 32 and 36, the first and second reservoirs 30 and 34 Is shut off, the inside of the first and second pressure chambers 21 and 24 is sealed and the pressure rises, and the hydraulic oil in these pressure chambers 21 and 24 passes through the conduits from the passages 31 and 35 and, for example, to the brake device. After that, a braking action corresponding to the brake pedal depression force is performed.

When the braking is released, the first and second pistons 4 and 5 are moved by 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. It is returned in the direction of arrow B. At this 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 help of the bending and the help of the flow groove 42, the first
And the hydraulic oil in the second supply chambers 22 and 25 passes through the holes 26 and 27, is quickly sent to the first and second pressure chambers 21 and 24, and the negative pressure is released, so that the first and second pistons 4 and 5 are released. Returns smoothly.

The first and second pistons 4 and 5 are further connected to the first and second piston cups 20 and 2.
3 is returned until it passes through ports 32 and 36, the first
Then, the sealed state of the second pressure chambers 21 and 24 is released, the excess hydraulic 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 action and the pumping action are performed, the overlaid portion 44 is provided on the back side of the flow groove 42,
No swelling or breakage due to R (R), and the durability is increased. Further, since the peripheral edge portion 41 a of the ring 41 has the ring-shaped groove 47,
And base surface 4 of second piston cups 20 and 23
It does not directly hit 0 and does not wear.

Although the embodiment of the present invention has been described above, the specific configuration is not limited to this, and changes or additions or other combinations in the claims may be appropriately made without departing from the gist of the present invention. It should be understood that this is possible.

[0028]

As described above in detail, according to the first aspect of the present invention, since the flow groove is provided, the build-up portion is provided on the back side of the position where the thin portion is formed, so that the flow groove expands. And no stress is concentrated, so there is no breakage. Therefore, even if there is a flow groove, there is no breakage and there is an effect that the durability becomes excellent.

The second aspect defines the size of the overlaid portion, which clarifies the significance of the formation of the overlaid portion, and defines the boundary between the circulation groove and the outer peripheral portion according to the third aspect. Due to the radius, the effect is obtained that the pressure is dispersed and it is hard to break.

According to the fourth aspect of the present invention, the peripheral edge of the ring is prevented from hitting the base surface by the ring-shaped groove, and the base surface is hardly worn and scratched. Therefore, in addition to the effects of the above effects,
Even when the ring is applied to the base surface, the ring is not broken or scratched and, in the worst case, does not split, resulting in excellent durability.

[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 part of the piston cup according to the embodiment of the present invention, in which the piston cup is cut away.

FIG. 5 is a partially cutaway plan view of a piston cup according to the embodiment of the present invention.

FIG. 6 is a cross-sectional view of a piston cup and its periphery showing another embodiment of the present invention.

FIG. 7 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 10 retaining ring 11 first pressure cup 12 second Pressure cup 13 hole 20,50 first piston cup (piston cup) 21 first pressure chamber 22 first supply chamber 23 second piston cup (piston cup) 24 second pressure chamber 25 second supply chamber 26,27 hole 28, 29 Stopper 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, 57 Flow groove 43 Outer peripheral portion 44 Overlay portion 45 , 53 Lip portion 46, 54 Mounting portion 47 Ring-shaped groove 52 Piston A, B Arrow R Lumpur

Claims (4)

[Claims] 1. A piston cup mounted on a piston to seal a gap between the piston and the cylinder, and having a flow groove on an outer peripheral portion through which hydraulic fluid passes, wherein the outer peripheral portion having the flow groove is provided. A piston cup provided with a built-up portion on the back side to supplement a thin portion generated by the flow groove. 2. The piston cup according to claim 1, wherein the build-up portion has a size corresponding to at least the flow groove. 3. The piston cup according to claim 1, wherein R is provided at a boundary between the flow groove and the outer peripheral portion. 4. A ring-shaped groove is provided in a base surface formed on a piston side of the piston cup according to claim 1 or 2, and a peripheral portion of a ring supporting the piston cup is positioned in the ring-shaped groove. Wherein the peripheral portion does not contact the base surface.