JPH1137102A - Accumulator and its diaphragms - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an accumulator, which is excellent in gas permeation resistance and which can be used for a long time, and a diaphragm used by the accumulator. SOLUTION: An accumulator is provided with a shell and an elastic, membraneous diaphragm 7 for the accumulator, which divides the inner space of the shell into two chambers one of which is filled with working oil. In this case, the elastic, membraneous diaphragm 7 for the accumulator contains, as the membrane forming element, a compound layer 5 made up of both a composite shielding layer 3 consisting of a gas shielding layer 1 and a water shielding layer 2 and elastic resin layers 4 layered on upper and lower surfaces of the layer 3. In addition, the water shielding layer 2 of the composite shielding layer 3 is positioned on more the working-oil-filled chamber side than the gas shielding layer 1. Moreover, the gas shielding layer 1 is made of the material containing an ethylene-vinyl acetate copolymer saponified substance, the water shielding layer 2 is made of a polyolefine resin, and the elastic resin layer 4 is made of the material containing a polyamide resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an accumulator used for a hydraulic device of an automobile, an industrial vehicle or the like, and a diaphragm for the accumulator used for the accumulator.

[0002]

2. Description of the Related Art An accumulator has a pressure accumulating function, and generally comprises a metal shell and an accumulator diaphragm held in the shell and dividing the shell into two chambers. Such an accumulator diaphragm is manufactured by forming a rubber material into a thin film having a predetermined shape, and serves to divide the inner space of the shell into two chambers. A gas (gas) such as nitrogen gas is sealed in one chamber (gas chamber) in the shell to become a pressure transmitting fluid, and a hydraulic oil is supplied to the other chamber (oil chamber) in accordance with the pressure of the liquid supply source. Is supplied. In this case, the gas sealed in one of the chambers gradually passes through the rubber thin-film diaphragm as the use period elapses, so that the gas sealing pressure is reduced and the function of the gas cannot be achieved.

Therefore, attempts have been made to improve the gas permeation resistance of the diaphragm for accumulators. For example, one saponified ethylene-vinyl acetate copolymer film is bonded between two rubber thin films. A rubber-resin composite film provided with an agent layer interposed has been proposed (JP-A-2-1659).
No. 48). The saponified ethylene-vinyl acetate copolymer (hereinafter abbreviated as "EVOH") is excellent in gas permeation resistance. Therefore, a diaphragm for an accumulator constituted by using the saponified ethylene-vinyl acetate copolymer can maintain a gas filling pressure. Becomes However, the above-mentioned rubber-resin composite film has a problem that the EVOH film cracks, peels off and the like when the use period is long.

[0004]

Therefore, the above EVOH
A proposal has been made in which a resin elastic film mainly composed of a polyamide resin is interposed between the film and the rubber thin film so that the EVOH film does not crack or the like. However, when the accumulator diaphragm having such a configuration is attached to the accumulator and used for a long period of time, the gas permeation resistance gradually decreases (with time), and the gas permeation resistance is no longer excellent. Problems arise. Further, if the gas permeation resistance is reduced as described above, there is a problem that the accumulator cannot be used for a long period of time.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an accumulator which has excellent gas permeation resistance and can be used for a long period of time, and a diaphragm for the accumulator used therefor.

[0006]

In order to achieve the above object, an accumulator according to the present invention comprises a shell and a diaphragm for an accumulator in the form of an elastic thin film which divides an inner space of the shell into two chambers. An accumulator in which a chamber is filled with hydraulic oil, wherein the elastic thin film-shaped diaphragm for an accumulator comprises a gas shielding layer (A) and a water shielding layer (B) described below. And a composite layer composed of the following resin elastic layers (C) laminated on both upper and lower surfaces thereof as a film-forming element, wherein the water shielding layer (B) in the shielding composite layer is more hydraulic oil than the gas shielding layer (A). It is configured to be positioned on the filling chamber side. (A) A gas shielding layer made of a material containing EVOH. (B) A water shielding layer made of a polyolefin resin. (C) A resin elastic layer made of a material containing a polyamide resin.

[0007] The accumulator diaphragm of the present invention is an elastic thin film accumulator diaphragm used at the interface between gas and hydraulic oil, wherein the accumulator diaphragm comprises the following gas shielding layer (A) and water shielding. A composite layer comprising a shielding composite layer comprising a layer (B) and the following resin elastic layers (C) laminated on both upper and lower surfaces thereof as a film-forming element, and a water shielding layer ( B) is configured such that it is positioned closer to the hydraulic oil than the gas shielding layer (A). (A) A gas shielding layer made of a material containing EVOH. (B) A water shielding layer made of a polyolefin resin. (C) A resin elastic layer made of a material containing a polyamide resin.

That is, the inventors of the present invention have conducted a series of studies to obtain an accumulator which is excellent in gas permeation resistance and can be used for a long period of time and a diaphragm for the accumulator used therefor. In the process, it was found that the aforementioned decrease in gas permeability resistance was caused by water absorption of EVOH. That is, the hydraulic oil filled in the oil chamber of the accumulator generally has high water absorption, and thus contains water with the long-term use of the accumulator. Then, the moisture permeates through the rubber or polyamide resin constituting the accumulator diaphragm, and
Reaches OH. Then, the EVOH absorbs water, and the gas permeability resistance is reduced. The inventor of the present invention has conducted research on preventing the above water from reaching the EVOH. As a result, the gas shielding layer (A) has a low water absorption polyolefin resin as a layer for protecting the EVOH from the water. If a water shielding layer (B) consisting of
The inventors have found that the intended purpose can be achieved, and have reached the present invention. In the present invention, the “hydraulic oil” means a liquid to be filled in an accumulator, and is a general term for a liquid generally used as a liquid pressure transmission medium such as a brake fluid.

[0009]

Next, an embodiment of the present invention will be described.

The accumulator of the present invention is constituted by using a shell and an accumulator diaphragm (hereinafter, simply referred to as "diaphragm") for dividing the inside of the shell into two chambers. One of the two compartments (one of the compartments) is filled with hydraulic oil.

The shell is not particularly limited as long as it is made of metal, but is usually made of iron or an aluminum alloy. The shape of the shell is not particularly limited, and is substantially spherical, cylindrical,
Various shapes such as a box shape are used. It is preferable that two divided shells having a substantially hemispherical shell shape are abutted and finished into a substantially spherical shell shape. By doing so, the peripheral edge of the diaphragm is positioned at the inner peripheral edge of the opening of the one hemispherical shell-shaped split shell, and a ring-shaped holding material is attached thereto, and the inner peripheral edge of the split shell opening and the ring The periphery of the diaphragm is sandwiched and fixed between the outer periphery of the shape holding member and the opening of one of the divided shells and the opening of the other divided shell are welded to finish the accumulator. Therefore, the manufacture of the shell becomes easier as compared with the conventional method of forming a shell by forming one disk into a spherical shell shape. Also, before welding the two split shells, the installation state of the diaphragm attached to the opening of one hemispherical shell-like split shell can be checked, so that the mounting failure of the peripheral edge of the diaphragm can be reliably avoided. Become. In addition, because the outer periphery of the ring-shaped holding portion and the inner periphery of the opening of the split shell sandwich and fix the periphery of the diaphragm, the periphery of the diaphragm can be firmly attached, preventing gas and hydraulic oil from leaking. become able to.

For example, as shown in FIG. 1, the above-mentioned diaphragm has a shielding composite layer 3 provided at its center with a gas shielding layer 1 made of a material containing EVOH and a water shielding layer 2 made of a polyolefin resin. Is provided. A resin elastic layer 4 made of a material containing a polyamide resin is provided on both upper and lower surfaces of the shielding composite layer 3 to form a composite layer 5. Further, rubber elastic layers 6 are provided on both upper and lower surfaces of the resin elastic layer 4. The water shielding layer 2 is positioned closer to the hydraulic oil than the gas shielding layer 1.

In the diaphragm 7, the material for forming the gas shielding layer 1 is not particularly limited as long as it contains EVOH.
[Component (a)] or a quaternary copolymer of EVOH with a polyamide 6, a polyamide 66, a polyamide 610, and a polyamide 612, and a terpolymer of ethylene-acrylate-maleic anhydride. A composition (component (b)) prepared by blending with EVO and EVO
A composition [component (c)] or the like in which a polyamide multi-component copolymer comprising at least two components of H, polyamide 6, and polyamide 66 and a maleic anhydride-modified ethylene-propylene copolymer are blended is used. Can be

When a composition (component (a)) made of EVOH is used as a material for forming the gas shielding layer 1, the gas shielding layer 1 having excellent gas permeation resistance can be formed at low cost. . Further, as a material for forming the gas shielding layer 1, a composition [(b) component] obtained by blending EVOH, a polyamide quaternary copolymer, and an ethylene-acrylate-maleic anhydride terpolymer is used. When used, in addition to good gas permeability resistance, it is possible to form the gas shielding layer 1 having excellent bending fatigue resistance especially in a low temperature environment. Further, as a material for forming the gas shielding layer 1, EV
When a composition (component (c)) comprising a mixture of OH, a polyamide multi-component copolymer and a maleic anhydride-modified ethylene-propylene copolymer is used, good gas transmission resistance and bending fatigue resistance are obtained. In addition, the moldability is excellent, and the dimensional accuracy of the obtained diaphragm 7 is improved.

It is preferable to use EVOH having an ethylene content of 25 to 50 mol%. Among them, those having an ethylene content of 32 mol% are preferred. That is, when the ethylene content is less than 25 mol%, the gas permeation resistance is improved, but the EVOH itself is hardened, the flexibility is reduced, and the EVOH tends to be unsuitable for applications having a bending motion. . Conversely, if the ethylene content exceeds 50 mol%, sufficient gas permeability resistance may not be ensured. The saponification degree of the vinyl acetate component in the EVOH is preferably set to 95 mol% or more, and more preferably 98 mol% or more, in consideration of gas permeability resistance and moldability.

Polyamide 6, Polyamide 66, Polyamide 610, Polyamide 6 used for component (b)
The polyamide quaternary copolymer composed of 12 components is EV
Polyamide 6 and polyamide 66 are preferred from the viewpoint that excellent bending fatigue resistance can be imparted without giving orientation to OH.
Is preferably set in the range of 50 to 80% by weight based on the total weight of the four components. That is, if the total blending ratio is less than 50% by weight, EV
This is because the amount of polyamide 6 and polyamide 66 having high compatibility with OH is too small, so that the reactivity between the polyamide quaternary copolymer and EVOH may be reduced, and the bending fatigue resistance may not be improved. On the other hand, if the total blending ratio exceeds 80% by weight, the amount of polyamide 6 and polyamide 66 having high compatibility with EVOH becomes too large, and the polyamide quaternary copolymer and EVOH react excessively to form a gel. This is because there is a possibility that the moldability may deteriorate.

The ethylene-acrylate-maleic anhydride terpolymer used for the component (b) is used together with the polyamide quaternary copolymer contained in the EVOH to reduce the elongation at break in a low-temperature environment. The reduction can be effectively suppressed, and the bending fatigue resistance is significantly improved.

In the above component (b), EVOH
[(P) component], a polyamide quaternary copolymer [(q) component], and an ethylene-acrylic acid ester-maleic anhydride terpolymer [(r) component]; p) / (q) / (r)] is (p) / (q) /
(R) = (60-90) / (5-35) / (5-35)
Is preferably set in the range. That is, E
If the mixing ratio of VOH is less than 60% by volume, EVOH
Is too small and gas permeation resistance may not be sufficiently exhibited.
If the content exceeds 0% by volume, the amount of the polyamide terpolymer and the ethylene-acrylate-maleic anhydride terpolymer may be too small to improve the bending fatigue resistance in a low-temperature environment. Because there is.

The polyamide multi-component copolymer comprising a polyamide component containing at least two components of polyamide 6 and polyamide 66 used in the component (c) is EV.
From the viewpoint that excellent bending fatigue resistance can be imparted without giving orientation to OH, the above polyamide 6 and polyamide 66
Is 50 to 50% of the total polyamide component.
Preferably, it is set in the range of 80% by weight. That is, if the total blending ratio is less than 50% by weight,
This is because the amount of polyamide 6 and polyamide 66 having high compatibility with EVOH is too small, the reactivity between the polyamide multi-component copolymer and EVOH is reduced, and there is a possibility that the bending fatigue resistance cannot be improved. Conversely, if the total blending ratio exceeds 80% by weight, the amount of polyamide 6 and polyamide 66 having high compatibility with EVOH becomes too large, and the polyamide multi-component copolymer and EVOH excessively react and gel. This is because the moldability may be deteriorated. Polyamide components other than the above two components include polyamide 11 and polyamide 1
2, polyamide 69, polyamide 610, polyamide 6
12 and the like.

The maleic anhydride-modified ethylene-propylene copolymer used in the component (c) is obtained by adding maleic anhydride to an ethylene-propylene copolymer. And by using together with the polyamide multi-component copolymer to be contained in the EVOH, it is possible to effectively suppress a decrease in elongation at break in a low-temperature environment,
Flexural fatigue resistance is significantly improved.

In the above component (c), EVOH
The weight-based compounding ratio of [(x) component], polyamide multi-component copolymer [(y) component], and maleic anhydride-modified ethylene-propylene copolymer [(z) component] [(x) /
(Y) / (z)] is (x) / (y) / (z) = (60
-85) / (5-30) / (10-35). That is, if the compounding ratio of EVOH is less than 60% by weight, the compounding amount of EVOH may be too small and gas permeation resistance may not be sufficiently exhibited, and the compounding ratio of EVOH exceeds 85% by weight. This is because the amount of the polyamide multi-component copolymer and the maleic anhydride-modified ethylene-propylene copolymer may be too small to improve the bending fatigue resistance in a low-temperature environment.

Examples of the polyolefin resin used as a material for forming the water shielding layer 2 include polyethylene, polypropylene and polybutene-1. Other than these, α, such as ethylene, propylene, and butene-1,
A copolymer of olefins or a copolymer of an α-olefin with another component, for example, a vinyl compound such as styrene, vinyl acetate or acrylonitrile may be used. Furthermore, using an unsaturated carboxylic acid such as maleic acid, fumaric acid, or acrylic acid, an ester or an acid anhydride thereof, or a product obtained by adding a hydroxyl group or an epoxy group to these polyolefin-based resins to improve adhesiveness. The one given may be used. Because these polyolefin resins have low water absorption, water permeation can be significantly reduced,
Therefore, the gas permeability resistance of the obtained diaphragm 7 is not reduced.

Examples of the polyamide resin used as the material for forming the resin elastic layer 4 include polyamide 6, polyamide 66, polyamide 610, polyamide 612 and the like, and these may be used alone or in combination. If such a polyamide resin contains the above-mentioned polyamide 6 or polyamide 66, the melting point of EVOH is approximated, so that various mixtures of polyamide 6 and other polyamide resins should be used. Is possible. In particular, when a polyolefin-based resin is blended with a polyamide resin, water permeation can be suppressed even in the resin elastic layer 4 due to the low water-absorbing polyolefin-based resin. A product having excellent properties can be obtained.

As the material for forming the rubber elastic layer 6, acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), epichlorohydrin-ethylene oxide copolymer rubber (ECO), fluoro rubber, chlorinated butyl rubber (Cl-IIR) ) And the like.
Among them, Cl-IIR is preferable because flexibility can be imparted to the entire diaphragm 7 and an effect of not causing a crack or the like due to bending motion can be sufficiently obtained.

In the present invention, for example, the diaphragm 7 is manufactured as follows, and an accumulator is manufactured using the diaphragm 7. That is, when the diaphragm 7 is manufactured, the material for forming the gas shielding layer 1, the material for forming the water shielding layer 2, and the material for forming the resin elastic layer 4 are co-extruded by using an extruder, thereby forming a gas. A resin elastic layer 4 is integrally formed on both upper and lower surfaces of a shielding composite layer 3 including a shielding layer 1 and a water shielding layer 2. In this case, the bonding interface between the gas shielding layer 1 and the resin elastic layer 4 is bonded by melting them, so that an adhesive is not required. On the other hand, the bonding interface between the water-shielding layer 2 and the resin elastic layer 4 is usually adhered by melting both of them, as described above, but a copolymer of α-olefins is used as a material for forming the water-shielding layer 2. If they are present, they do not adhere to each other due to their fusion, so that they need to be subjected to an adhesion imparting treatment in advance. Next, on both upper and lower surfaces of the resin elastic layer 4,
A conventionally known adhesive is applied. Then, after laminating the rubber elastic layer 6 formed in a layer shape, it is vulcanized and adhered. In this way, a diaphragm 7 having a layer structure as shown in FIG. 1 is obtained. In addition, the diaphragm 7 can be obtained by a conventionally known method such as a laminating method other than the above-described manufacturing method.

Next, as shown in FIG. 2, the diaphragm 7 thus obtained is placed on the inner peripheral edge of the opening of the lower divided shell 11 of the two substantially hemispherical shells. The peripheral portion is positioned, and the peripheral portion is sandwiched and fixed between the outer peripheral portion of the ring-shaped holding member 12 and the inner peripheral portion of the opening of the lower divided shell 11 to thereby fix the lower divided shell 11.
Attached to. At this time, the water shielding layer 2 in the shielding composite layer 3 of the diaphragm 7 is attached so as to be positioned closer to the hydraulic oil filling chamber side 16 than the gas shielding layer 1. Then, the opening of the upper split shell 13 is brought into contact with the opening of the lower split shell 11 and subjected to electron beam welding or the like, and then one of the two chambers separated by the diaphragm 7 is filled with hydraulic oil. Thus, the accumulator 14 is configured. In the figure, 15 is a poppet.

In the diaphragm 7, the thickness of the gas shielding layer 1 is preferably set in the range of 10 to 100 μm. More preferably, 25 to 8
The range is 5 μm. That is, by setting the value within the above range, gas permeation can be effectively suppressed.

The water shielding layer 2 has a thickness of 20 to 1
It is preferable that the distance is set in the range of 00 μm. More preferably, it is in the range of 30 to 70 μm. That is,
This is because, by being set in the above range, the permeation of water can be effectively suppressed, and the gas permeation resistance due to the absorption of EVOH does not significantly decrease.

The thickness of the resin elastic layer 4 is 15
It is preferable that the distance be set in the range of 150 μm.
More preferably, it is in the range of 50 to 110 μm. That is, by setting the value within the above range, the obtained diaphragm 7 can be given appropriate flexibility.

Further, the thickness of the rubber elastic layer 6 is 50
Preferably, it is set in the range of 0 to 1500 μm. More preferably, it is in the range of 700 to 1500 μm. That is, by setting the value within the above range, the obtained diaphragm 7 can be given appropriate flexibility.

It should be noted that the diaphragm of the present invention is not limited to the above-mentioned laminated structure, and may have a structure as shown in FIG. 3, for example. That is, the water shielding layer 2 is formed on the liquid (hydraulic oil) side (lower surface) of the gas shielding layer 1, and the resin elastic layer 4 ′ and the gas elastic layer 4 ′ are formed on the gas side surface (upper surface) of the gas shielding layer 1. Any number of the shielding layers 1 ′ may be alternately stacked in this order to form the shielding composite layer 3. Then, a resin elastic layer 4 is formed on both upper and lower surfaces of the shielding composite layer 3, and a rubber elastic layer 6 is formed on both upper and lower surfaces of the resin elastic layer 4. In the case of the structure shown in FIG. 3, from the viewpoint of the bending fatigue resistance of the obtained diaphragm 7 ', the number of layers of the resin elastic layer 4' and the gas shielding layer 1 'formed on the upper surface of the gas shielding layer 1 is And about 2 to 6 are preferable.

Next, examples will be described together with comparative examples.

[0033]

Embodiments 1 and 2 First, in manufacturing a diaphragm,
EVOH (ethylene content 32 mol%, F-101 manufactured by Kuraray Co., Ltd.) was prepared as a material for forming a gas shielding layer, and a polyolefin resin (HDP) was used as a material for forming a water shielding layer.
E, Admer manufactured by Mitsui Petrochemical Co., Ltd.), and a polyamide resin (Super Tough Nylon ST811HS manufactured by DuPont) was prepared as a material for forming the resin elastic layer. Further, Cl-IIR (JSR1066 manufactured by Nippon Synthetic Rubber Co., Ltd.) was prepared as a material for forming the rubber elastic layer. Next, the material for forming a gas shielding layer, the material for forming a water shielding layer, and the material for forming a resin elastic layer were co-extruded using an extruder to produce a six-layer laminate. Next, a conventionally known adhesive was applied to both the upper and lower surfaces of the six-layer laminate, and a rubber elastic layer forming material was press-formed into a layer using a press, followed by vulcanization bonding. Thus, the diaphragm 7a shown in FIG.
I got The thickness of each layer is shown in Table 1 below.

[0034]

Comparative Examples 1 to 3 A diaphragm was obtained in the same manner as in Example 1 except that the water shielding layer was not formed and the thickness of each layer was as shown in Table 1 below.

[0035]

[Table 1]

[0036]

Example 3 Next, in the same manner as in Example 1, an eight-layer laminate was produced by coextrusion from an extruder, and rubber elastic layers were formed on the upper and lower surfaces of the eight-layer laminate. Thus, the diaphragm 7b shown in FIG. 5 was obtained.

[0037]

Example 4 Similarly to Example 1, a ten-layer laminate was produced by coextrusion from an extruder, and rubber elastic layers were formed on both upper and lower surfaces of the ten-layer laminate. Thus, the diaphragm 7c shown in FIG. 6 was obtained.

Using the thus obtained diaphragm, a nitrogen gas permeation test was performed by the method described below, and the results are shown in Table 2 below.

[Nitrogen gas permeation test] First, the obtained diaphragm was formed so as to have a surface area of 100 cm ^2, and this was mixed with water at the interface between nitrogen gas and a liquid consisting of brake fluid and with nitrogen gas and brake fluid. Each was installed at the interface with the liquid containing the volume%. Then, the nitrogen gas permeation amount of this diaphragm was measured at 100 ° C. ×
The measurement was performed under the conditions of 1000 hr × 150 kgf / cm ² .

[0040]

[Table 2]

In all of the above embodiments, the water shielding layer is provided on the liquid (brake fluid) side of the gas shielding layer, so that the amount of water reaching the gas shielding layer can be significantly reduced.
It can be seen that excellent gas permeation resistance is maintained for a long time. On the other hand, in Comparative Examples 1 to 3, since the water shielding layer was not formed, moisture permeated to the gas shielding layer, indicating that the gas permeability resistance was reduced.

Next, an accumulator was manufactured using the above-described diaphragm in the following manner.

[0043]

Fifth Embodiment As shown in FIG. 7, an upper split shell 21 and a lower split shell 22 are prepared as two substantially hemispherical shells, and the diaphragms 7a and 7a obtained in the above embodiment are prepared. 7b and 7c (hereinafter referred to as "diaphragm 7" in this paragraph) were formed with thick peripheral portions. Then, as shown, the lower split shell 22
Is fixed to the inner peripheral surface of the opening with a ring-shaped holding member 12 '. In this case, as shown in FIG. 8, a groove 24 is formed in the circumferential direction in advance on the inner peripheral surface of the opening of the lower split shell 22, and a step 25 is formed below the groove 24. The ring-shaped holding member 12 'has a stepped structure in which a ring-shaped upper side has a large diameter and a lower side has a small diameter, and the upper side has an inner periphery of an opening of the lower split shell 22 as shown in FIG. The step 25 is positioned on the end face of the thick portion of the diaphragm 7 and the lower portion is positioned on the thick portion of the diaphragm 7. Then, in this state, the ring-shaped holding member 12 'is swaged as shown in FIG. 9 by using a swaging device (not shown). As a result, the peripheral thick portion of the diaphragm 7 is connected to the lower peripheral portion of the ring-shaped holding member 12 ′,
The lower split shell 22 is pinched and fixed to the inner peripheral surface of the opening.
As a result of this caulking, the central portion on the upper side of the ring-shaped holding member 12 ′ is inserted into the groove 24 formed in the inner circumferential surface of the opening of the lower split shell 22 along the circumferential direction. Therefore, the degree of fixation of the ring-shaped holding member 12 ′ is improved, and the degree of sealing between the ring-shaped holding member 12 ′ and the lower split shell 22 is improved. Therefore, the lower split shell 22
Gas and hydraulic oil are prevented from permeating and leaking from between the and the ring-shaped holding member 12 '. Also, the step 25 provided on the inner peripheral surface of the opening of the lower split shell 22 allows
The displacement of the ring-shaped holding member 12 'does not occur, and the effect of improving the positioning accuracy of the ring-shaped holding member 12' can be obtained. In this way, the lower split shell 22
The diaphragm 7 is attached, and the opening of the upper split shell 21 is aligned with the opening of the lower split shell 22 as shown in FIG. 7 to finish the shell into a substantially spherical shell as a whole.
In this case, before the upper split shell 21 is attached, the attachment state of the diaphragm 7 can be checked with the naked eye, thereby making it possible to prevent the occurrence of a defective attachment of the diaphragm 7. And, the upper split shell 21
Is joined to the opening of the lower split shell 22 by electron beam welding or the like at the joint between the two openings. As a result, the penetration width can be reduced,
It is possible to reduce or avoid the thermal effect on the peripheral thick portion of the diaphragm 7. Thus, an accumulator 14 'as shown in FIG. 7 is obtained. In FIG. 7, 26 is an electron beam weld, 15 'is a poppet, 2
7 is a plug having an oil port 28, and 29 is a gas plug. In this accumulator 14 ′, the inner space of the shell is formed by the diaphragm 7 into the gas chamber 30 and the hydraulic oil filling chamber 1.
The water shielding layer 2 of the diaphragm 7 is positioned closer to the hydraulic oil filling chamber 16 ′ than the gas shielding layer 1. The alternate long and short dash line indicates a state in which the diaphragm 7 is elastically deformed. The four types of accumulators thus obtained (each having a different diaphragm structure) have high durability and long life.

Although the upper shell 21 and the lower shell 22 form a substantially spherical shell in FIG. 7, the shape of the shell is not limited to a spherical shell, but may be a cylindrical shell.
Various shapes such as a box shape can be used. In FIG. 7, the spherical shell is formed by using two hemispherical shell-shaped divided shells 21 and 22. However, as in the conventional case, a spherical shell or the like is formed by using a single plate. A shell may be made and the diaphragm of the present invention may be mounted thereon.

[0045]

As described above, the accumulator of the present invention comprises a shielding composite layer comprising a gas shielding layer made of a material containing EVOH and a water shielding layer made of a polyolefin resin, and polyamide The diaphragm is configured using a diaphragm including, as a film forming element, a composite layer formed by laminating a resin elastic layer made of a resin-containing material, and the water shielding layer is positioned on the side of the hydraulic oil filling chamber. For this reason, it is possible to reduce the amount of water reaching the gas shielding layer by the water shielding layer.
Since the water absorption of OH can be significantly reduced, excellent gas permeation resistance can be maintained for a long period of time. Therefore, compared to the conventional accumulator, it can be used for a long time.

In the accumulator of the present invention, the shell constituting the accumulator is finished in a substantially spherical shell shape obtained by combining two substantially hemispherical shells. It is positioned inside the opening of the substantially hemispherical shell-shaped split shell and attached by fixing it with a ring-shaped holding material. When the openings are butted and welded, there is no gas leakage or hydraulic oil leakage from the diaphragm attachment portion or the butted portion, and there is an advantage that the pressure accumulating function can be sufficiently exhibited.

Further, the diaphragm according to the present invention is provided with an EVO
A composite comprising a gas-shielding layer made of a material containing H and a water-shielding layer made of a polyolefin-based resin, and a resin elastic layer made of a material containing a polyamide resin laminated on both upper and lower surfaces thereof. A layer is included as a film forming element. Therefore, it is optimal to be incorporated in the accumulator of the present invention.

In the case where the rubber elastic layer is formed on the upper and lower surfaces of the resin elastic layer via the adhesive layer in the diaphragm, the excellent elastic force of the rubber elastic layer and the resin elastic layer can be utilized. It has the advantage of being extremely excellent in flexibility and further excellent in bending fatigue resistance.

Further, a gas shielding layer is laminated on one side of the water shielding layer as a shielding composite layer of the above-mentioned diaphragm, and a resin elastic layer and a gas shielding layer are alternately arranged in an arbitrary number in this order on one side of the gas shielding layer. In the case of being laminated, there is an advantage that the gas permeation resistance and the bending fatigue resistance are extremely excellent, and the excellent performance can be maintained for a long time.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of an accumulator diaphragm according to the present invention.

FIG. 2 is a partial sectional view showing an accumulator in which the diaphragm for accumulator of the present invention is incorporated.

FIG. 3 is a sectional view showing another example of the diaphragm for accumulator of the present invention.

FIG. 4 is a sectional view showing an embodiment of the diaphragm for accumulator of the present invention.

FIG. 5 is a sectional view showing another embodiment of the diaphragm for accumulator of the present invention.

FIG. 6 is a sectional view showing still another embodiment of the diaphragm for accumulator of the present invention.

FIG. 7 is a sectional view showing an embodiment of the accumulator according to the present invention.

FIG. 8 is a cross-sectional view of a main part of FIG. 7, showing a state before a ring-shaped holding member is caulked to a lower split shell.

FIG. 9 is a cross-sectional view of main parts showing a state after the ring-shaped holding member is caulked to the lower split shell in FIG.

[Explanation of symbols]

 Reference Signs List 1 gas shielding layer 2 water shielding layer 3 shielding composite layer 4 resin elastic layer 5 composite layer 7 diaphragm for accumulator

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08F 218/18 C08F 218/18 C08G 69/00 C08G 69/00

Claims (5)

[Claims] 1. An accumulator comprising a shell and an elastic thin film-shaped diaphragm for an accumulator dividing an inner space of the shell into two chambers, wherein one of the chambers is filled with hydraulic oil, The above-mentioned elastic thin film-shaped diaphragm for accumulator is provided with the following gas shielding layer (A).
And a resin elastic layer (C) laminated on both upper and lower surfaces thereof as a film-forming element, as a film-forming element. An accumulator, wherein the layer (B) is positioned closer to the hydraulic oil filling chamber than the gas shielding layer (A). (A) A gas shielding layer comprising a material containing a saponified ethylene-vinyl acetate copolymer. (B) A water shielding layer made of a polyolefin resin. (C) A resin elastic layer made of a material containing a polyamide resin. 2. The shell according to claim 1, wherein said shell is formed into a substantially spherical shape by combining two substantially hemispherical shaped shells. It is attached by being positioned inside the opening of the shell and fixed by a ring-shaped holding material, and the opening of one substantially hemispherical shell-like shell in the attached state abuts the opening of the other substantially hemispherical shell-like divided shell. 2. The accumulator according to claim 1, wherein the accumulator is welded. 3. An accumulator diaphragm in the form of an elastic thin film used at an interface between gas and hydraulic oil, wherein the accumulator diaphragm includes a gas shielding layer (A) and a water shielding layer (B) described below. A shielding composite layer and the following resin elastic layers (C) laminated on both upper and lower surfaces
Wherein the water shielding layer (B) in the shielding composite layer is positioned closer to the hydraulic oil than the gas shielding layer (A). (A) A gas shielding layer comprising a material containing a saponified ethylene-vinyl acetate copolymer. (B) A water shielding layer made of a polyolefin resin. (C) A resin elastic layer made of a material containing a polyamide resin. 4. The diaphragm for an accumulator according to claim 3, wherein rubber elastic layers are laminated on both upper and lower surfaces of the resin elastic layer via an adhesive layer. 5. The shielding composite layer, wherein a gas shielding layer (A) is laminated on one surface of a water shielding layer (B), and a resin elastic layer (C) is provided on one surface of the gas shielding layer (A). Layer (A)
5. The diaphragm for accumulator according to claim 3, wherein an arbitrary number of the diaphragms are alternately stacked in this order.