JP2003028391A - Gas storage tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lightweight highly safe storage tank capable of taking a form suitable for mounting. SOLUTION: A multilayer structure is used suitably providing space between each layer, check valves 6 and 7 allowing a flow from an inner layer to an outer layer are provided on partition walls 4 and 5 between each layer, a filling port for gas is provided in a center layer 1, and an exhaust port is provided in an outermost layer 3. The partition walls 4 forming each layer are circularly arced, and an installation mode part is formed in an outer circumferential wall 10. A pressure of gas in the outermost layer 3 is equalized with an external pressure of the gas exhaust port 12a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas storage tank, for example, mounted on a natural gas vehicle to store compressed natural gas as a fuel for the engine.

[0002]

2. Description of the Related Art Conventionally, automobiles have been developed that use fossil fuels, which cause serious pollution problems, as fuels with gas such as natural gas and hydrogen, which emit less pollutants.
Fig. 3 shows the structure of a natural gas vehicle, engine 2
A gas storage tank 21 is mounted as a fuel tank for supplying fuel to 0.

As a fuel, especially natural gas, whose main component is methane, contains a large amount of hydrogen, produces a small amount of carbon dioxide, and emits a small amount of sulfur oxides and nitrogen oxides. Suitable as fuel for automobiles. Moreover, because it is already distributed as fuel in various places,
It is easy to spread.

However, since the specific gravity of gas is much lower than that of liquid or solid, it occupies a huge volume under normal pressure. There, the gas is usually liquefied and its volume is reduced. However, for example, natural gas has a boiling point of −160 ° C. under atmospheric pressure, and it is very difficult to keep it in a liquid state. Therefore, recently, 20MPa (200kg) has been added to natural gas.
The mainstream is to store in the gas phase by compressing by applying a pressure of f / cm ² ). Natural gas in the vapor phase is generally compressed natural gas (CNG).
al Gas) is called.

Therefore, when natural gas is used as a fuel, the gas storage tank 21 stores 20 to store natural compressed gas.
It must have a high pressure resistance capable of withstanding a high pressure of MPa. In the conventional tank, the outer peripheral wall is formed of a thick metal plate to obtain pressure resistance. However, this increased the weight of the tank.

In order to have pressure resistance, a sphere which is uniformly applied with pressure is most suitable as a form. Other forms, such as ellipsoids and barrels, are preferable as spheres. However, the form according to the sphere is
It lacks stability in taking up a lot of space to mount it on a car and fixing it in a fixed position.

Further, in order to supply the high pressure gas in the tank as fuel to the engine, it is necessary to reduce the pressure of the gas until it can be used as fuel. Therefore, the gas storage tank 21
It was usual to install a regulator for lowering the pressure of the gas in the middle of the pipe for supplying the gas. But,
Since the gas in the tank is very high, it is necessary to use a high-performance regulator that reliably lowers it to a safe pressure to use it as fuel in the engine. Due to the high pressure, there was a possibility of causing serious danger such as engine failure and explosion.

[0008]

The conventional gas storage tank has a large weight, and when mounted on a vehicle using gas as fuel, not only the fuel consumption is deteriorated, but also the operability is deteriorated. There is also a problem that the pressure resistant tank is not suitable for mounting. Furthermore, in order to use the gas in the tank as fuel, a high-performance regulator for lowering the pressure of the gas was required.

Further, in the case of a conventional gas storage tank, when a crack occurs in the outer peripheral wall due to an accident or the like, there is a large difference between the pressure inside the tank and the pressure outside the tank, so that the gas may be ejected from the crack at once. Become. This caused the tank to explode,
There was a high risk of causing an explosion or fire due to the ignition of the ejected gas.

An object of the present invention is to provide a gas storage tank which eliminates the inconveniences of the conventional example, is light in weight, can take a form suitable for mounting, and is highly safe. .

[0011]

In order to achieve the above object, the present invention firstly has a multilayer structure in which an appropriate space is provided between the respective layers, and a partition wall between the respective layers allows a flow from the inner layer to the outer layer. A check valve is provided, a gas filling port is provided in the central layer, and a discharge port is provided in the outermost layer. Secondly, the partition wall forming each layer is formed into an arc shape, and installed on the outer peripheral wall. Thirdly, the gist is to form the portion, and thirdly, to make the pressure of the gas in the outermost layer equal to the external pressure of the gas outlet.

According to the first aspect of the present invention, it is possible to disperse the pressure of the gas in the tank to each layer by forming the tank into a multi-layer structure. Furthermore, by providing a check valve that allows the flow from the inner layer to the outer layer on the partition wall of each layer, the pressure difference between each layer can be automatically maintained below a certain value.
It is also possible to create a flow from the inner layer to the outer layer.
Therefore, by providing the gas filling port in the central layer and the exhaust port in the outermost layer, the gas put in the central layer can be taken out from the outermost layer, and the filling and discharging of the gas into the tank is easy. .

According to the second aspect of the invention, in addition to the above-mentioned action, the partition wall forming each layer is formed into an arc-shaped pressure-resistant form, whereby the pressure resistance can be enhanced, and further the outer peripheral wall of the tank. May have a shape different from the inner side such as forming an installation form part, and by providing a form suitable for installation, the tank itself can have a form suitable for mounting on the vehicle body.

According to the third aspect of the present invention, the gas in the tank is supplied as fuel by making the pressure of the gas in the outermost layer equal to the pressure outside the gas discharge port.
Eliminates the need for a regulator to reduce gas pressure.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. In the present invention, the gas stored in the tank is not particularly limited, but the present embodiment is a case of storing natural gas. Further, although the use of the present invention is not limited, the present embodiment is assumed to be a fuel tank mounted on an automobile running on natural gas as fuel.

FIG. 1 is a vertical side view showing an embodiment of a gas storage tank of the present invention, and FIG. 2 is a horizontal plan view of the same as above. The gas storage tank of the present invention has a three-layer structure in which an appropriate space is provided between layers. The center layer 1 is provided at the center of the tank, the intermediate layer 2 is provided so as to surround the center layer 1, and the outermost layer 3 is provided around the middle layer 2. Note that the number of layers is not necessarily three, and a two-layer structure or a multi-layer structure of three or more layers may be used.

The tank is formed as a container by the outer peripheral wall 10, and the outer peripheral wall 10 has an outer form.
The outermost layer 3 and the intermediate layer 2 are separated from each other inside the outer peripheral wall 10 by the first partition wall 5. Further, inside the partition wall 5, the intermediate layer 2 and the central layer 1 are partitioned by the second partition wall 4. Further, the outer peripheral wall 10, the partition wall 5, and the partition wall 4 are fixed in mutual positions by the ribs 8, and the shapes of the intermediate layer 2 and the outermost layer 3 are maintained.

The partition wall 4 is provided with a first check valve 6 which allows the flow from the inner layer to the outer layer. The check valve 6 naturally opens when a pressure difference of a certain value or more is applied, and irreversibly causes the gas to flow from the high pressure portion to the low pressure portion. Thereby, the pressure difference between the central layer 1 and the intermediate layer 2 can be automatically kept below a certain value. In the first embodiment, the check valve 6
Due to this, the pressure difference between the central layer 1 and the intermediate layer 2 is automatically always less than 10 MPa.

The partition wall 5 is provided with a second check valve 7 which allows the flow from the inner layer to the outer layer. The check valve 7 basically has the same function as the check valve 6. This allows
The pressure difference between the middle layer 2 and the outermost layer 3 is always 5 automatically.
It becomes below MPa.

In this embodiment, when the tank is fully filled with gas, the central layer 1 has a pressure of 20 MPa and the intermediate layer 2 has a pressure of 10 MPa.
The outermost layer will be filled with natural gas at a pressure of 5 MPa. At this time, the pressure difference between the central layer 1 and the intermediate layer 2 is 10 MPa, and therefore the partition wall 4 has only to have the strength to withstand the pressure of 10 MPa. For some reason, if the pressure difference between the central layer 1 and the intermediate layer 2 exceeds 10 MPa, the check valve 6 opens and the gas in the central layer 1 is discharged to the intermediate layer 2. Central layer 1
Therefore, the pressure difference between the intermediate layer 2 and the intermediate layer 2 is promptly reduced to 10 MPa.

Since the same operation is performed between the partition wall 5, the intermediate layer 2 and the outermost layer 3, the intermediate layer 2 and the outermost layer 3 are formed.
The pressure difference between them is 5 MPa or less, and the partition wall 5 is only required to withstand a pressure of 5 MPa. Further, since the pressure of the outermost layer 3 is 5 MPa, the outer peripheral wall 10 has only to withstand the pressure of 5 MPa.

As described above, since the pressure difference between the layers is small, the strength required for the partition wall is also low. Further, the partition wall has an ellipsoidal shape and a shape suitable for pressure resistance.
For these reasons, even if the partition wall is formed of a thin plate surface, sufficient pressure resistance can be provided. This makes it possible to reduce the overall weight of the tank. Forming a lightweight tank is very important to improve fuel efficiency and operability of a vehicle when it is mounted on the vehicle.

A flat surface 9 is formed on the bottom of the outer peripheral wall 10 of the tank as an installation mode portion. As a result, it is easy to install and is stable when mounted on a vehicle. Although illustration is omitted, it is also conceivable to further change the shape according to the installation of other pipes or equipment as an installation form part, or to provide a recess or a protrusion. With such a shape suitable for installing the tank, the pressure resistance of the tank becomes low, but in the present embodiment, the pressure of the natural gas in the outermost layer 3 is low, and therefore, the pressure of the natural gas in the outermost layer 3 is small. Since the pressure difference is small, there is no problem because the required pressure resistance is low. In addition, the small pressure difference between the outer side of the tank and the outer peripheral wall of the tank makes it possible to provide sufficient pressure resistance even if the outer peripheral wall of the tank is made thin, and thus the weight of the tank can be reduced.

On the other hand, since the pressure of the outermost layer 3 is low, even if the outer peripheral wall 10 is damaged due to a crack or the like due to an accident or the like, the pressure difference with the outside air is small and the pressure applied to the crack is small. As a result, the crack is accelerated by the pressure of the gas, and accordingly, the amount of the gas ejected in the tank is increased at an accelerated rate, so that it is unlikely that the tank itself will eventually explode. Further, since the pressure difference with the outside air is small, the momentum of the gas ejected from the crack is also reduced, so that the amount of gas leaking from the crack can be reduced. This can reduce the risk of the leaked gas catching fire and causing an explosion. These features are
When there is a high possibility of receiving a large shock from an accident, such as a car, and there is no choice but to install something that causes a fire, such as an electrical system, near the tank,
It greatly contributes to enhancing safety.

A filling pipe 11 is provided from the outside of the tank to the center layer 1, and a tip thereof is used as a filling port 11a which opens to the center layer 1. Further, a discharge pipe 12 is provided from the outermost layer 3 to the outside of the tank. A discharge port 1 that opens the end of 12 to the outermost layer 3
2a.

The filling pipe 11 is joined to the filling pipe 16 via the coupling 13 outside the tank, and the filling pipe 16 extends to the filling port provided outside the vehicle body. The discharge pipe 12 is joined to the supply pipe 17 via the coupling 14 outside the tank, and the supply pipe 17 has a regulator 15
Is provided to guide the engine 20.

When the natural gas is filled into the tank mounted on the vehicle body, the natural gas is filled from an inlet provided outside the vehicle body. Connect the filling machine with the filling port for filling natural gas,
Natural gas pressurized by the filling machine is injected from the inlet. The natural gas passes through the filling pipe 16 and the filling pipe 11,
Enter the central layer 1. Natural gas collects in the central layer 1, the pressure in the central layer 1 increases, and the pressure difference with the intermediate layer 2 is 10 MPa.
If it becomes above, the check valve 6 will open and natural gas will flow into the intermediate | middle layer 2.

When natural gas collects in the intermediate layer 2 and the difference between the intermediate layer 2 and the outermost layer 3 becomes 5 MPa or more, the check valve 7 opens and the natural gas flows into the outermost layer 3. After that, the pressures in the central layer 1, the intermediate layer 2, and the outermost layer 3 all increase, and when the pressure in the central layer 1 reaches 20 MPa, the tank is assumed to be fully filled and gas is filled. To cancel. At that time, the pressure in the middle layer 2 naturally is 10MP.
The pressure inside the outermost layer 3 is 5 MPa. By thus filling the central layer 1 with natural gas, it is possible to automatically fill all the layers with natural gas.

When the natural gas is discharged from the tank, it is discharged from the discharge pipe 12. The natural gas passing through the exhaust pipe 12 passes through the supply pipe 17, and is supplied to the engine through the regulator 15 in the supply pipe 17. As the natural gas is discharged from the discharge pipe 12, the pressure in the outermost layer 3 decreases. As a result, the pressure difference between the outermost layer 3 and the intermediate layer 2 is 5
When the pressure exceeds MPa, the check valve 7 opens, and natural gas flows from the middle layer 2 to the outermost layer 3. The natural gas in the middle layer 2 is reduced and the pressure is lowered, and the pressure difference with the central layer 1 is 10 MPa.
When the above is reached, the check valve 6 opens and natural gas flows from the central layer 1 to the intermediate layer 2. In this way, by discharging the natural gas from the outermost layer 3, it is possible to automatically discharge the natural gas stored in each layer.

The pressure inside the outermost layer 3 is 5 MPa, which is almost the same as the pressure in the engine section. Therefore, it is not necessary to reduce the pressure when supplying natural gas from the tank to the engine section.

In this embodiment, a regulator 15 is provided in the supply pipe 17, and the pressure of the natural gas supplied to the engine is reduced to 5 MPa which is the pressure of the engine. This is for some reason the outermost layer 3
It is present to prevent damage to the engine when the internal pressure becomes 5 MPa or higher, or when the pressure of natural gas discharged from the tank rises, and is usually unnecessary. Therefore, the regulator 15 does not need to have very high performance, and the regulator 15 itself is hardly burdened. For this reason, the engine is safe without abnormal load on the engine due to malfunction of the regulator.

[0032]

As described above, the gas storage tank of the present invention has a multi-layered structure so that the pressure of the gas in the tank can be dispersed in each layer, which makes it lightweight and suitable for installation. It becomes a tank and is highly safe.

[Brief description of drawings]

FIG. 1 is a vertical side view showing an embodiment of a gas storage tank of the present invention.

FIG. 2 is a cross-sectional plan view showing an embodiment of the gas storage tank of the present invention.

FIG. 3 is a perspective view showing a structure of a natural gas vehicle.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Central layer 2 ... Intermediate layer 3 ... Outermost layer 4 ... Partition wall 5 ... Partition wall 6 ... Check valve 7 ... Check valve 8 ... Rib 9 ... Flat surface 10 ... Outer peripheral wall 11 ... Filling pipe 11a ... Filling port 12 ... Exhaust pipe 12a ... Exhaust ports 13, 14 ... Coupling 15 ... Regulator 16 ... Injection pipe 17 ... Supply pipe 20 ... Engine 21 ... Gas storage tank

Claims (3)

[Claims] 1. A multi-layer structure in which an appropriate space is provided between each layer,
A gas storage tank characterized in that a check valve for allowing a flow from an inner layer to an outer layer is provided on a partition wall between layers, a gas filling port is provided in a central layer, and a discharge port is provided in an outermost layer. 2. The gas storage tank according to claim 1, wherein the partition wall forming each layer has an arc shape, and the installation form portion is formed on the outer peripheral wall. 3. The gas storage tank according to claim 1, wherein the pressure of the gas in the outermost layer is made equal to the external pressure of the gas outlet.