JPH0752401Y2 - Bladder accumulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a bladder type accumulator. This accumulator can be applied to, for example, hydraulic equipment such as a vehicle brake mechanism and a cypress mechanism.

[Prior Art] In fluid equipment such as hydraulic equipment, a bladder type accumulator is used for accumulating pressure and avoiding pulse pressure. This bladder type accumulator is composed of a shell having a substantially spherical hollow chamber, and a reversible rubber diaphragm that partitions the hollow chamber of the shell into a gas chamber and an oil chamber. In this accumulator, upon use, nitrogen gas is sealed in the gas chamber and the oil chamber is connected to the hydraulic equipment. Then, the diaphragm is inverted according to the pressure difference between the oil chamber and the gas chamber, and the working oil is stored in the oil chamber or the working oil stored in the oil chamber is discharged to the hydraulic device.

By the way, in this accumulator, when the usage period becomes long or the usage environment temperature becomes high, the nitrogen gas in the gas chamber gradually permeates the rubber diaphragm and enters the oil chamber. Therefore, problems such as a decrease in pressure in the gas chamber and a mixture of nitrogen gas as bubbles in the oil of the hydraulic equipment occur.

Therefore, in recent years, as disclosed in Japanese Patent Application Laid-Open No. 63-190902, an accumulator having a structure in which a metal foil is attached to almost the entire area of a rubber diaphragm, and a streak is formed on the metal foil is further proposed. It has been developed and the gas blocking function of the metal is made to avoid the permeation of nitrogen gas.

Further, as disclosed in Japanese Patent Laid-Open No. 63-203901, an accumulator having a structure in which a metal film member partially having a slit is embedded in a rubber diaphragm has been developed. In this accumulator, although the slit penetrates the metal membrane member and nitrogen gas permeates there from, the slit area is extremely small compared to the area of the entire diaphragm, so that the gas permeation amount can be considerably reduced.

In the above-mentioned two accumulators, the deformability of metal, which has a remarkably small elongation as compared with rubber, is compensated for by the lines and slits.

[Problems to be Solved by the Invention] The present invention takes the above-mentioned conventional diaphragm one technological step further and adopts a method of reducing the permeation area through which gas such as nitrogen gas permeates and increasing the permeation distance, Thus, it is an object of the present invention to provide a bladder type accumulator that suppresses gas from passing through the diaphragm.

[Means for Solving the Problem] A bladder type accumulator of the present invention comprises a shell having a substantially spherical hollow chamber, and a diaphragm fixed to the shell to divide the hollow chamber of the shell into a gas chamber and a liquid chamber, The diaphragm is composed of a rubber layer and at least two barrier layers having gas impermeability or gas impermeable, which are arranged side by side in the rubber layer at predetermined intervals and in a staggered manner in a cross section along the thickness direction. It is characterized by being configured.

The shell holds the diaphragm, and can have the same structure as the conventional one. The shell has a hollow chamber having a substantially spherical shape. Here, the substantially spherical shape means that the vertical inner diameter and the horizontal inner diameter of the hollow chamber are not significantly different from each other, and includes a shape similar to a spherical shape or an oval shape.

The diaphragm is composed of a rubber layer and at least two barrier layers which are arranged in a row in the rubber layer at predetermined intervals and in a staggered manner in a cross section along the thickness direction.

The rubber layer of the diaphragm can be formed of a known rubber material.
The thickness of the rubber layer can be appropriately selected, but can be, for example, about 4 to 8 mm.

The material for forming the blocking layer can be selected in consideration of ductility, cost, type of fluid, etc., and generally can be metal or resin. The metal can be, for example, aluminum-based or copper-based, and the resin can be, for example, polyvinylidene chloride-based or polyamide-based.

The blocking layer may be flat along the rubber layer and may be bellows in some cases. The number of blocking layers may be two or more, and may be three, four, or more. The thickness of one blocking layer can be appropriately selected, for example, from 20 to
The thickness can be 50 μm, but is not limited to this.

When the blocking layer is a metal layer, the metal layer can be formed by laminating a metal by a PVD method or the like, or by embedding or bonding a metal foil or a metal sheet in a rubber layer.

The outer blocking layer may be exposed on the exposed surface of the rubber layer or may be embedded inside the rubber layer.

In the accumulator of the present invention, the barrier layer usually has less elongation than the rubber layer, so that the rubber portion of the rubber layer between the barrier layers adjacent to each other is an easily deformable portion. It Therefore, when the diaphragm is deformed, the easily deformable portion that is easily deformed is mainly deformed.

In the accumulator of the present invention, when the blocking layer has low swelling property and non-swelling property with respect to oil and the liquid chamber is the oil chamber, the blocking layer is exposed on the side of the diaphragm facing the oil chamber. obtain. In this case, since the blocking layer comes into contact with the hydraulic oil in the oil chamber, the degree of contact of the hydraulic oil with the rubber layer can be reduced, which is advantageous for suppressing the swelling of the rubber layer due to the hydraulic oil. It is advantageous for suppressing gas permeation due to swelling.

[Operation] The working fluid is stored in the liquid chamber or the stored working fluid is sent to the fluid device at the pressure of the gas chamber according to the fluid pressure of the fluid device equipped with the accumulator. At this time, the diaphragm is deformed in the hollow chamber of the shell.

In the accumulator of the present invention, since the barrier layers are alternately arranged in parallel on the rubber layer of the diaphragm, gas permeation through the diaphragm is suppressed by the gas barrier function of the barrier layer. Even if it is transmitted, the amount of transmission is very small.

Moreover, in the accumulator of the present invention, since the blocking layers are alternately arranged side by side in the thickness direction of the diaphragm, the gas that permeates the rubber layer of the diaphragm cannot permeate at the shortest distance, but bypasses and permeates. Therefore, the transmission distance becomes longer. Therefore, the amount of gas permeated through the diaphragm is further reduced.

[Embodiment] An accumulator of the present invention will be described below with reference to an embodiment shown in FIGS. The overall structure of the accumulator of this embodiment is shown in FIGS. 1 and 2.

The accumulator of this embodiment comprises a shell 1 having a substantially spherical hollow chamber 10 and a diaphragm 2 mounted in the hollow chamber 10 in a bowl shape.

The shell 1 is formed by joining the upper shell 11 and the lower shell 12 by electron beam welding. A gas introduction hole 13 is formed on the top side of the upper shell 11, and the gas introduction hole 13 is closed by a plug 14. An oil introduction hole 15 is formed on the bottom side of the lower shell 12, and the oil introduction hole 15 communicates with hydraulic equipment.

The diaphragm 2 is fixed to the mounting portion 16 of the shell 1 via a ring-shaped holder 17. As a result, the diaphragm 2 partitions the hollow chamber 10 of the shell 1 into a gas chamber 10a and an oil chamber 10b as a liquid chamber.

A cross section of the main part of the diaphragm 2 is shown in FIG. In its cross section, the diaphragm 2 has a rubber layer 20 made of butyl rubber,
The rubber layers (20) are composed of aluminum metal layers (21, 23) as blocking layers, which are arranged side by side in a staggered manner in the thickness direction.
The thickness of each of the metal layers 21 and 23 is about 20 μm. Third
The figure shows a state in which a combination of the metal layer 21 and the metal layer 23 is developed two-dimensionally, and it is shown that almost the entire area of the diaphragm 2 is covered with the metal layer 21 and the metal layer 23. Note that FIG. 5 shows a state in which only the metal layer 21 is developed in a plane. Further, FIG. 6 shows a state in which only the metal layer 23 is developed in a plane.

As shown in FIG. 5, the metal layer 21 is composed of a plurality of fan-shaped inner metal layers 21a arranged concentrically and a plurality of fan-shaped outer metal layers 21b arranged concentrically. There is.
Therefore, the metal layer 21 has a structure composed of a plurality of independent metal layers.

Further, as shown in FIG. 6, the metal layer 23 is composed of a plurality of fan-shaped inner metal layers 23a arranged concentrically and a plurality of fan-shaped outer metal layers 23b arranged concentrically. Has been done. Therefore, the metal layer 23 has a structure composed of a plurality of independent metal layers.

In this embodiment, the inner metal layer 21a shown in FIG. 5 has a distance d1 of about 1 mm, the outer metal layer 21b has a distance d2 of about 1 mm, and the outer edge of the inner metal layer 21a and the inner edge of the outer metal layer 21b are separated from each other. The distance d3 is about 2 mm. In addition, the inner metal layer 2 shown in FIG.
3a The distance d5 between the comrades is about 1 mm, the outer metal layer 23b The distance d6 between the comrades
Is about 1 mm, and the distance d7 between the inner edge of the inner metal layer 23a and the outer edge of the outer metal layer 23b is about 2 mm.

Here, in the rubber layer 20, the portion corresponding to the distance d1 is the easily deformable portion 20a, the portion corresponding to the distance d2 is the easily deformable portion 20b, and the portion corresponding to the distance d3 is the easily deformable portion 20c. Of the 20, a portion corresponding to the interval d5 is an easily deformable portion 20g, a portion corresponding to the interval d6 is an easily deformable portion 20h, and a portion corresponding to the interval d7 is an easily deformable portion 20i. Easy deformable parts 20a to 20c, Easy deformable part 2
0g ~ 20i is not laminated with metal and consists only of rubber,
It is easy to deform.

In this embodiment, the distances d1 to d3 between the metal layers 21 and the distance d5 between the metal layers 23.
The metal layer 2 is where the metal such as ~ d7 is not laminated.
After laminating 1, 23, it was formed by partially removing the corresponding portion by etching treatment, but when laminating the metal layers 21, 23, the corresponding portion should be masked to be a metal non-laminated portion. Can also be formed by.

In this embodiment, as shown in FIG. 1, the diaphragm 2
A poppet 22 is attached to the center of the. The thickness of the diaphragm 2 is about 5 mm.

Next, the operation of the accumulator of this embodiment will be described together with its usage. First, at the time of use, nitrogen gas (10 to 20 atm) is sealed from the gas introduction hole 13 in the gas chamber 10a, and the oil introduction hole 15 is connected to a hydraulic device. Here, when the pressure of the nitrogen gas sealed in the gas chamber 10a exceeds the pressure of the hydraulic fluid of the hydraulic equipment, the entire diaphragm 2 faces downward as shown in FIG. It follows the inside.

When the pressure of the hydraulic oil in one hydraulic device overcomes the pressure in the gas chamber 10a, the hydraulic oil on the hydraulic device side is sent from the oil introduction hole 15 to the oil chamber 10b and stored in the oil chamber 10b. In this case, the central portion of the diaphragm 2 is pressed by the hydraulic oil and approaches the gas chamber 10a side as shown by the chain double-dashed line in FIG. Furthermore, the oil chamber 10b
When the amount of hydraulic oil stored in the diaphragm 2 increases, the base of the diaphragm 2 is greatly bent so as to form a substantially “U” shape as shown by the solid line in FIG. The diaphragm 2 is turned upside down as it approaches the inner surface of 11. In this state, the pressure in the gas chamber 10a increases,
Accumulated.

If the oil pressure of the hydraulic equipment drops again, the gas chamber 10a
As shown by the solid line in FIG. 1, the diaphragm 2 is pressed toward the lower shell 12 side by the accumulated pressure, and the entire diaphragm 2 faces downward. Along with this, the hydraulic oil in the oil chamber 10b is sent from the oil introduction hole 15 to the hydraulic equipment side.

By the way, in this embodiment, when the diaphragm 2 is deformed, the easily deformable portions 20a to 20c and 20g to 20i are mainly deformed.
This is because the easily deformable portions 20a to 20c and 20g to 20i are made of only rubber and the metal layers 21 and 23 are not laminated, so that the easily deformable portions are easily deformed.

Here, as described above, the inner metal layers 21a and the outer metal layers 21b of the metal layer 21 are independent from each other, and the inner metal layers 23a and the outer metal layers 23b of the metal layer 23 are independent from each other.
Therefore, when the diaphragm 2 is deformed, the inner metal layer 21a of the metal layer 21, the outer metal layer 21b, and the inner metal layer of the metal layer 23.
The outer metal layer 23a and the outer metal layer 23b are displaced independently of each other and hardly interfere with each other. Therefore, occurrence of unreasonable force and stress concentration on the metal layers 21 and 23 can be suppressed as much as possible. Therefore, the life and durability of the metal layers 21 and 23 can be further enhanced, and the blocking function of blocking gas such as nitrogen gas can be maintained for a long period of time.

Further, the permeation amount of the nitrogen gas in the gas chamber 10a that permeates the diaphragm 2 and enters the oil chamber 10b is proportional to the permeation area according to Fick's law regarding diffusion, and is inversely proportional to the permeation distance traveled by the nitrogen gas. . That is, when the permeation area becomes small or the permeation distance becomes long, the amount of permeated gas decreases. In this respect, in this embodiment, since the diaphragm 2 is covered with the metal layers 21 and 23 over almost the entire area, the gas permeation area is extremely smaller than the surface area of the entire diaphragm 2. Also, regarding the permeation distance, since the metal layers 21 and 23 are alternately arranged in the thickness direction of the diaphragm 2, when the nitrogen gas in the gas chamber 10a enters the oil chamber 10b, the nitrogen gas permeates at the shortest distance. However, the nitrogen gas must be bypassed as indicated by the arrow W in FIG. 4, and the permeation distance of the nitrogen gas is accordingly lengthened. As described above, in this embodiment, the permeation area is small and the permeation distance is long. Therefore, even if the permeation of nitrogen gas occurs, the amount becomes very small and there is no practical problem.

[Other Embodiments] In the above embodiments, the rubber layer 20 of the diaphragm 2 has a structure in which a total of two metal layers 21 and 23 are embedded in a staggered manner in the thickness direction, but the present invention is not limited to this. As in the other embodiment shown in FIG. 7, the metal layers 23 may be alternately arranged below the metal layer 21 with respect to the metal layer 21 to form a total of three layers. In this case, when the nitrogen gas in the gas chamber 10a permeates the diaphragm 2 and enters the oil chamber 10b, the nitrogen gas must further detour and the permeation distance becomes longer. It is advantageous to further suppress.

[Advantage of the Invention] According to the bladder type accumulator of the present invention, since the barrier layer having gas impermeability or gas impermeability is disposed on the rubber layer of the diaphragm, the fluid permeation area is compared with the surface area of the entire diaphragm. And extremely less. In addition, since the barrier layers are alternately arranged in the thickness direction of the diaphragm, and gas such as nitrogen gas must be bypassed for permeating the diaphragm, the gas permeation distance becomes long accordingly. Since the gas permeation area is small and the gas permeation distance is long as described above, the permeation amount of gas such as nitrogen gas can be further reduced.

According to the bladder type accumulator of the present invention, when the diaphragm is deformed, the rubber portion of the rubber layer between the barrier layers is mainly deformed, so that it is possible to prevent the force and stress concentration from occurring in the barrier layer. This is advantageous for extending the life of the barrier layer.

[Brief description of drawings]

1 to 6 show an embodiment of the present invention. FIG. 1 is a sectional view of an accumulator before the diaphragm is inverted, and FIG.
The figure is a cross-sectional view of the accumulator after the diaphragm is inverted, FIG. 3 is a developed view in which the metal layer is developed in plan view, FIG. 4 is an enlarged cross-sectional view of the essential part of the diaphragm along the thickness direction, and FIG. FIG. 6 is a development view in which one metal layer is developed in a plane, and FIG. 6 is a development view in which the other metal layer is developed in a plane. FIG. 7 shows another embodiment of the present invention and is an enlarged cross-sectional view of the essential part of the diaphragm. In the figure, 1 is a shell, 10 is a hollow chamber, 10a is a gas chamber, 10b is an oil chamber, 2 is a diaphragm, 20 is a rubber layer, 21 is a metal layer (blocking layer), and 23 is a metal layer (blocking layer). .

Claims (1)

[Scope of utility model registration request] 1. A shell having a substantially spherical hollow chamber and a diaphragm fixed to the shell for partitioning the hollow chamber of the shell into a gas chamber and a liquid chamber, the diaphragm having a rubber layer and a thickness. A cross section along the direction,
At least 2 having a gas impermeability or a gas impermeable property, which are arranged in parallel in the rubber layer at predetermined intervals and in an alternating manner.
A bladder-type accumulator characterized in that it is constituted by a barrier layer of layers.