RU2141073C1 - High pressure vessel - Google Patents

Abstract

FIELD: storage, distribution and transportation of liquid and gases; high-pressure vessel having cases made from composite materials; automotive industry; transport facilities working on gaseous fuel. SUBSTANCE: high-pressure vessel has metal envelope, at least one neck and load-bearing housing mounted on the outside; this housing consists of two layers of composite material. Hermetic load-bearing layer embracing the metal envelope is made from woven reinforcing material (A₁) impregnated with binder (C₁) at ratio A₁:C₁ equal to (40-70):(30-60); ratio of relative elongation at rupture of material A₁ to relative elongation of hardened binder C₁ ranges from 1 to 4. In particular case, load-bearing layer located above hermetic load-bearing layer may be made from unidirectional reinforcing material A₂ impregnated with binder C₂ at ratio A₂:C₂ equal to (68-82):(18-32); ratio of relative elongation at rupture of material A₂ to relative elongation of hardened binder C₂ ranges from 0.9 to 5.5 and ratio of relative elongation at rupture of materials A₁ and A₂ ranges from 1 to 3.5. Optimal ratio between thickness of hermetic load-bearing layer and thickness of load-bearing layer is equal to 1:(2-15). Stiffeners may be provided on surface of metal envelope directed inside vessel at areas where cylindrical portion changes to bottoms. EFFECT: enhanced strength and operational safety at rather small mass per unit of volume. 4 cl, 1 dwg, 1 tbl

Description

 The invention relates to techniques for storage, distribution and transportation of gases and liquids, and in particular to pressure vessels with bodies made of composite materials, and can be used, in particular, in the automotive industry when converting vehicles to gas fuel.

 Known high-pressure cylinder containing a cylindrical shell made of steel and having hemispherical bottoms, in one of which a flange is hermetically fixed (Vessels and pipelines of high pressure. Reference book. M .: Mechanical Engineering, 1990, p.6).

 The disadvantage of this cylinder is the large mass, which sharply limits the scope of its use.

 A known container for storing compressed gas containing layers of fibrous material, reinforced in the axial and annular directions (US patent, 3508677, 65 D 25/00, 1977). This design provides a smaller mass of the cylinder than metal, however, it is difficult to manufacture and, in addition, cannot guarantee its safe destruction, which usually occurs in the bottom area with the departure of the metal embedded element.

 It is safer to use a cylinder containing an external cylindrical power shell made of composite material (fiberglass), having hemispherical bottoms, in at least one of which a metal flange is hermetically fixed, and an internal metal sealing shell (DE, patent, 3821852, F 17 C 1/02, 1990).

 Another way to increase the reliability of a pressure vessel is realized in a cylinder containing a mandrel of a polymeric material with internal and external composite layers of high-strength fibers impregnated with a polymeric binder placed on it (RU, patent, 2100200, B 29 D 22/00, 1997). The disadvantage is the difficulty of manufacturing this cylinder.

 The closest analogue of the claimed technical solution in terms of the set of essential features and the achieved result is a high pressure vessel containing a thin metal shell having at least one neck, and a housing comprising one or more composite layers of fibrous material impregnated with a binder (GB, patent, 1379160, F 17 C 1/16, 1975). The disadvantages of this vessel include a marked decrease in strength upon repeated filling with a working medium.

 The objective of the present invention was to increase the strength and safety of operation of a pressure vessel while providing a relatively small mass per unit of usable volume.

The problem is solved in that the pressure vessel contains a metal shell, at least one neck and an external housing made of two layers of composite material, while the hermetically-force layer covering the metal shell is made of woven reinforcing material (A ₁ ), impregnated binder (C ₁₎ at a ratio of A _1: C ₁ is equal to (40-70) :( 30-60), wherein the ratio of the elongation at break of the material _A1 to the value of elongation of the cured binder C ₁ 1-4 leaves.

Additional differences of the invention are that the force layer located above the hermetically-force layer is made of unidirectional reinforcing material A ₂ impregnated with a binder C ₂ with a ratio of A ₂ : C ₂ equal to (68-82) :( 18-32 ), the ratio of the relative elongation at break of the material A ₂ to the relative elongation of the cured binder C ₂ is 0.9-5.5, and the ratio of the values of elongation at break of the materials A ₁ and A ₂ is 1-3.5.

 Another additional difference is that the ratio between the thickness of the hermetically-force layer and the thickness of the force layer is 1: 2-15.

 In addition, the vessel can be made up of a cylindrical part and bottoms with stiffeners on the surface of the metal shell facing the inside of the vessel at the points of transition of the cylindrical part to the bottoms.

 The drawing shows a General view of a pressure vessel with a partial longitudinal section. The vessel contains a metal shell 1 with at least one neck 2, on the shell there is a hermetically-force composite layer 3 of a woven reinforcing material impregnated with a binder, over which a power layer 4 of a composite material, for example, of a unidirectional reinforcing material impregnated with a binder, is placed. In the place of transition of the cylindrical part of the vessel to the bottoms, stiffeners 5 (an optional structural element) are made on the metal shell.

The vessel is made as follows. The sealed-force layer 3 is formed on a mandrel, which is a metal shell 1, by "wet" winding a woven reinforcing material impregnated with a binder, followed by curing. It was experimentally established that to obtain a gas-tight vessel, it is necessary to observe the mass ratio of the reinforcing woven material (A ₁ ) and the epoxy binder (C ₁ ) equal to (40-70): (30-60). It was also established that to ensure the tightness of layer 3 in the entire load range, the ratio of the relative elongation at break of the woven reinforcing material (L _A1 ) to the relative elongation of the cured binder (L _C1 ) should be 1-4.

 The power layer 4 of the composite material is placed above the hermetically-force layer.

 All of the above set of features ensures the achievement of the intended technical result - obtaining a vessel, characterized by increased strength and safety of operation with a relatively small mass.

The formation of the force layer 4 can be performed, for example, by winding the finished prepreg or single strands of unidirectional reinforcing material (A ₂ ), impregnated with a binder (C ₂ ), on the hermetically-force layer 3 and subsequent curing. The task of the power layer is to take on the power load arising from the working medium (for example, gas) inside the vessel under high pressure. It was experimentally shown that the optimal mass ratio of A ₂ : C ₂ is (68-82) :( 18-32). Depending on the selected ratio, “dry” or “wet” windings are implemented.

As a unidirectional reinforcing material of high strength, high-modulus fiberglass, organo- or carbon fiber can be used. Optimum reinforcing materials and a binder are those that provide a ratio of the relative elongation at break of the reinforcing material (L _A2 ) to the relative elongation of the cured binder (L _C2 ) equal to 0.9-5.5.

For the most full use of the elastic-plastic properties of reinforcing materials in a pressure vessel, the ratio L _A1 : L _C2 should be 1-3.5.

A special case of the execution of the pressure vessel provides a ratio between the thickness of the hermetically-force layer (S ₁ ) and the thickness of the force layer (S ₂ ) equal to 1: 2-15. In addition, in the particular case of execution, the vessel may include a cylindrical part and bottoms, for example having a parabolic surface, while stiffening ribs are made on the surface of the metal shell facing the inside of the vessel at the transition points of the cylindrical part to the bottoms.

 Example 1

For the manufacture of a pressure vessel, including a cylindrical part, bottoms with a parabolic surface and a neck, a metal shell of aluminum with a wall thickness in the cylindrical part of not more than 1 mm is used. As a woven reinforcing material, glass tape (SL) of the LES-0.15-35 brand (GOST 5931-81) is used, and as a unidirectional reinforcing material, glass roving (CB-glass fiber) of the PBM10-1200 brand (TU 6-06-31- 502-85) with a ratio of L _A1 : L _A2 = 1.05. As an epoxy binder, a system consisting of a mixture of ED-20 brand Diane resin (GOST 10587-84) and diethylene glycol diglycidyl ether grade DEG-1 (TU 6-05-1823-77) with a ratio of ED-20: DEG-1, equal to 60:40, and hardener - triethanolaminate titanate TEAT-1 (TU 6-05-1860-79) with a ratio of (ED-20 + DEG): TEAT equal to 100: 10. This achieves the ratio L _A1 : L _C1 and L _A2 : L _C2 , respectively, equal to 2.5 and 2.6. The ratio A ₁ : C _{1 is} chosen equal to 65:35, the ratio A ₂ : C ₂ = 75:25, and S ₁ : S ₂ = 1: 3.5.

 Example 2

The vessel was made analogously to example 1, except that stiffeners were made on the inner surface of the metal shell at the points of transition of the cylindrical part to the bottoms, carbon fiber based roving (HC) was used as reinforcing unidirectional material (TU 6-05-1875-77) and the mixture ED-20: TEAT-1 = 100: 10 was taken as a binder for the power layer, which ensures the ratios L _A2 : L _C2 = 0.9, L _A1 : L _A2 = 3.5 and S ₁ : S ₂ = 2.

 The table shows the main characteristics of the pressure vessels in examples 1, 2.

 As follows from the data presented in the table, the pressure vessels according to this invention with a relatively small bulk density are gas impermeable, have a significant margin of safety and withstand more than 15,000 refills, which ensures their safe operation.

Claims (4)

1. A pressure vessel containing a metal shell, at least one neck and an external power housing made of two layers of composite material, characterized in that the hermetic-force layer covering the metal shell is made of woven reinforcing material (A ₁ ), impregnated binder (C ₁₎ at a ratio of a _1: C ₁ is equal to (40 - 70): (30 - 50), wherein the ratio of elongation at break a material ₁ to the value of elongation of the cured binder C ₁ compiled t 1 - 4. 2. The vessel according to claim 1, characterized in that the force layer located above the hermetically-force layer is made of unidirectional reinforcing material A ₂ impregnated with a binder C ₂ , with a ratio of A ₂ : C ₂ equal to (68 - 82): (18 - 32), while the ratio of the relative elongation at break of the material A ₂ to the relative elongation of the cured binder C ₂ is 0.9 - 5.5, and the ratio of the values of elongation at break of the materials A ₁ and A ₂ is 1 - 3,5.  3. The vessel according to claim 1 or 2, characterized in that the ratio between the thickness of the airtight-strength layer and the thickness of the force layer is 1: 2 to 15.  4. A vessel according to any one of claims 1 to 3, characterized in that it includes a cylindrical part and bottoms, while stiffening ribs are made on the surface of the metal shell facing the inside of the vessel at the transition points of the cylindrical part to the bottoms.

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