[Title of Invention]

Fuel Tank

[Technical Field]

[0001]

This invention relates to a fuel tank.

[Background Art]

[0002]

In an internal combustion engine that uses liquefied fuel, the liquefied fuel is stored in a tank. However, when the temperature is elevated, the liquefied fuel is gasified to elevate the pressure in the tank which may cause the tank to burst. Therefore, for example, the ratio of gas space to the whole internal volume of the tank with liquefied petroleum gas (LPG) must not be more than 85 percent, according to the Japanese standard for handling LPG automobiles.

[0003]

That is, a space of a predetermined ratio must remain in the fuel tank that stores the liquefied fuel after the tank has been filled with liquefied fuel.

[0004]

In order to prevent the fuel from overfilling, taking into account complex tank structures, float-type conventional fuel tanks are used for preventing

overfilling .

[0005]

Patent literature (PTL) 1, for instance, discloses a technique that utilizes a liquid surface sensor.

Further, technologies that provide an air chamber in the fuel tank have been disclosed in PTLs 2 and 3.

[0006]

However, according to the technology of PTL 1, the fuel that is filled in the fuel tank up to a

predetermined amount is detected by a liquid level sensor, and a fuel feed pump is stopped by a special device. Further, the technologies of PTLs 2 and 3 relate to the fuel tanks having complex structures.

[Citation List]

[Patent Literature]

[0007]

[PTL 1] JP 9-209979A

[PTL 2] JP 7-132738A

[PTL 3] JP 10-184464A

[Summary of Invention]

[Technical Problem]

[0008]

It is an object of the present invention to provide a fuel tank of a simple structure without any special device but having space of a predetermined ratio after the fuel tank has been filled with liquefied fuel.

[Solution to Problem]

[0009]

According to the invention described in claim 1, there is provided a fuel tank, wherein the fuel tank is of a form in which a number of cylindrical containers are arranged in parallel and are coupled together in a manner that the cylindrical containers neighboring each other share common partitioning walls, respectively; each of the partitioning walls has a passage through which the neighboring cylindrical containers are communicated with each other; the upper ends of the passages are formed leaving partly the inner partitioning walls so that the liquid will not enter into the upper parts of the cylindrical containers; and when the liquid is fed into the fuel tank, space of a predetermined volume is formed on the surface of the liquid.

[0010]

That is, in the invention of claim 1, if liquefied fuel is injected into the fuel tank, the injected liquefied fuel flows through the communication passages of the inner partitioning walls and is injected into the cylindrical containers. The upper ends of the

communication passages of the inner partitioning walls are formed leaving partly the inner partitioning walls so that the liquefied gas fuel will not enter into the upper parts of the cylindrical containers. The position of the surface of the liquefied fuel injected into the

cylindrical containers becomes the position of the upper end portions, and gas formed by the gasification of the liquefied fuel remains over the surface of the liquid. That is, a gaseous space forms on the surface of the liquid in each cylindrical container. The ratio of the gaseous space to the whole internal volume of the tank has been specified for filling the storage tank with the liquefied fuel. Upon determining, in advance, the upper end positions of the communication passages of the inner partitioning walls so as to meet the specified filling ratio,, it is possible to fill the liquefied fuel at a predetermined ratio relying on a simple structure without using any special device.

[0011]

According to an invention described in claim 2, there is provided a fuel tank, wherein the fuel tank is of a form in which a number of spherical containers are arranged in parallel and are coupled together in a manner that the spherical containers neighboring each other share common partitioning walls, respectively; each of the partitioning walls has a passage through which the neighboring spherical containers are communicated with each other; the upper ends of the passages are formed leaving partly the inner partitioning walls so that the liquid will not enter into the upper parts of the

spherical containers; and when the liquid is fed into the fuel tank, space of a predetermined volume is formed on the surface of the liquid.

[0012]

That is, in the invention ^!' of claim 2, the fuel tank is of a form in which a number of spherical containers are arranged in parallel and are coupled together to provide the fuel tank that exhibits the same effects as those of the fuel tank described in claim 1.

[0013]

According to an invention described, in claim 3, there is provided the fuel tank of claim 1 or 2, wherein the volume of the space is not less than 15 percent of the whole internal volume of the fuel tank.

[0014]

That is, the invention of claim 3 provides the fuel tank which when, for example, the LPG is to be stored, meets the filling ratio of not more than 85 percent specified under the Japanese standard for handling LPG automobiles.

[0015]

The inventions described in claims provide a fuel tank of a simple structure without any special device but having a space of a predetermined ratio after the fuel tank has been filled with the liquefied fuel.

[Brief Description of Drawings]

[0016]

[Fig. 1] is a sectional view schematically

illustrating the constitution of an embodiment of when the invention is applied to a fuel tank.

[Fig. 2] is a sectional view illustrating the fuel tank of Fig. 1 in another cross section.

[Fig. 3] is a perspective view showing the

appearance of the fuel tank of Fig. 1, wherein I-I is the sectional position of Fig. 1 and II-II is the sectional position of Fig. 2.

[Fig. 4] (A) and 4(B) are . sectional views

schematically illustrating the constitutions of other embodiments of when the invention is applied to the fuel tank.

[Fig. 5] is a view schematically illustrating the constitution of a further embodiment of when the

invention is applied to the fuel tank, wherein (A) is a plan view of an outer shape and (B) is an elevation in cross section at a position of III-III in (A) . [Description of Embodiments]

[0017]

Embodiments of the invention will now be described with reference to the accompanying drawings. In the plurality of accompanying drawings, the same or

corresponding members are denoted by the same reference -numerals.

[0018]

Fig. 3 shows the appearance of fuel tank 1 of the invention for storing a liquefied fuel such as LPG, ammonia, etc. Fuel tank 1 is of a form in which a number of cylindrical containers are arranged in parallel and are coupled together. Fig. 2 is a sectional view of a portion indicated by an arrow II-II in Fig. 3, and shows a portion where there is no communication passage in inner partitioning walls 8. The cylindrical containers, as is well known, have excellent resistance against the pressure, and the thickness of the cylindrical containers can be easily designed so as to satisfy the standards of pressure resistance. Namely, fuel tank 1 can be easily designed to satisfy the standards of pressure resistance required for the liquefied fuel.

[0019]

Fig. 1 is a sectional view of a portion indicated by an arrow I-I in Fig. 3, and shows a portion having communication passages in inner partitioning walls 8. If the liquefied fuel is injected into fuel tank 1 through fuel inlet port 2, injected liquefied fuel 5 flows through the communication passages of the inner

partitioning walls and is injected into the cylindrical containers. Upper ends 9 of the communication passages of the inner partitioning walls are formed leaving partly the inner partitioning walls so that liquefied gas fuel 5 will not enter into the upper parts of the cylindrical containers. The position of surface 6 of liquefied fuel 5 injected into the cylindrical containers becomes the position of upper end portions 9. Namely, gaseous space formed chiefly by the gasification of the liquefied fuel stays over surface 6 of the liquid in the cylindrical containers; i.e., gaseous space 7 is formed therein. In Fig. 1, the rightmost cylindrical container only has vent 4, and the liquefied fuel is filled therein. If the liquefied fuel passes through vent 4, a cut-off gas valve (not shown) provided in vent 4 operates to stop the filling of the fuel.

[0020]

In the above description, the cylindrical containers of the fuel tank 1 do not have to be all of the same size, do not have to be arranged in parallel on the same plane, but may have a form shown, for example, in Fig. 4 (A) or 4 (B) depending on the limitations of a place on where fuel tank 1 is installed. Fig. 4(A) shows an embodiment in which the cylindrical containers of fuel tank 1 have dissimilar sizes and Fig. 4(B) shows an embodiment in which the cylindrical containers of fuel tank 1 are not arranged on the same plane. Also in these embodiments, communication passages are formed in the inner partitioning walls, and upper ends 9 of the

communication passages are so formed that gaseous space 7 stays therein.

[0021]

When mounted on a vehicle, therefore, fuel tank 1 can have a complex shape as shown in Fig. 5. Fig. 5 shows an embodiment of when fuel tank 1 is so formed as can be mounted on a vehicle astride of the driveshaft.

[0022]

The filling ratio has been specified for storing the liquefied fuel in the storage tank. Upon determining, in advance, the upper end positions of the communication passages of the inner partitioning walls in a manner that the volume of gaseous space 7 satisfies the specified filling ratio, therefore, it is allowed to fill the liquefied gas fuel at a predetermined ratio in the fuel tank of a simple structure without using any special device. According to the Japanese standard for handling LPG automobiles, for example, the filling ratio of the LPG has been specified as not more than 85 percent.

Therefore, the volume of gaseous space 7 may be set at not less than 15 percent.

[0023]

In the foregoing fuel tank 1 of a form in which a number of cylindrical containers were arranged in parallel and were coupled together was described.

However, it will be easily understood from Figs. 1 to 5 that the same effects are exhibited even when the ^' number of containers that are arranged in parallel have a spherical shape.

[Reference Signs List]

[0024]

1 fuel tank

2 fuel inlet port

3 fuel outlet port

4 vent

5 liquefied fuel

6 surface of liquid

7 gaseous space

8 partitioning wall

9 upper end of passage