Claims:We Claim:
1. A fuel tank (100) in a gravity feed fuel injection system, comprising at least:
an inlet (102) with a first cap (103); and
an outlet (104); characterized in that
a second cap (105);
a spring (106); and
a plate (107).

said second cap (105) located on said fuel tank (100) and in engagement with said spring (106) in a manner such that rotation of said second cap (105) varies the tension of said spring (106); and

said plate 107 attached to said spring 106 and adapted to move under said tension of said spring 106 in a direction such that fuel (108) stored within said fuel tank 100 is pressurized.

2. The fuel tank (100) of claim 1, wherein said second cap 105 is a screw plug.

3. The fuel tank (100) of claim 1, wherein a force balancer (110) is located in between said spring (106) and said plate (107).

4. A gravity feed fuel injection system (200), comprising at least
a fuel tank (100) comprising an inlet 102, outlet 104, and a first cap 103;
a filter (202);
a metering unit (204);
a high pressure pump (206); and
an injector (208), characterized in that
a second cap (105) located on said fuel tank (100) and in engagement with said spring (106) in a manner such that rotation of said second cap (105) varies the tension of said spring (106); and

said plate 107 attached to said spring and adapted to move under said tension of said spring 106 in a direction such that fuel (108) stored within said fuel tank is pressurized.

5. The fuel injection system of claim 1, wherein said fuel injection system is a common rail fuel injection system. , Description:Field of the invention
[0001] This invention relates to the field of a fuel tank in a gravity feed fuel injection system.

Background of the invention
[0002] A fuel tank is used to store fuel in a fuel injection system. In a gravity feed fuel injection system the inlet pressure to the high pressure pump is less, because the only parameter that is causing the fuel to flow is gravity. An electric feed pump is used to pump the fuel from the fuel tank to a fuel filter and into the high pressure pump. For low cost applications, the use of an EFP adds to the cost of the system. Moreover, since the pressure at which fuel needs to be sent out of the fuel tank is approximately in range of 1-2 bar, an EFP is not required especially if fuel flow is of gravity type. Hence there is a need for a fuel tank that is capable of generating fuel pressure at least equivalent to that of an EFP.
[0003] Prior art patent application 4522/CHE/2015 discloses a fuel tank in a gravity feed fuel injection system, comprising at least an inlet for receiving fuel. A lid is located in the fuel tank in a manner such that the lid pressurizes the fuel stored in the fuel tank through a spring and a lever mechanism, the spring in engagement with the lid, a first end of the lever is pivotally attached to the fuel tank and a second end of the lever is in engagement with the spring.

Brief description of the accompanying drawing
[0004] Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:
[0005] FIG. 1 illustrates a fuel tank used in gravity feed fuel injection system.

Detailed description of the embodiments
[0006] FIG. 1 illustrates a fuel tank 100 used in gravity feed fuel injection system. The fuel tank 100 comprises at least an inlet 102 with a first cap 103 and an outlet 104. The fuel tank 100 comprises at least a second cap 105, a spring 106, and a plate 107. The second cap 105 is located on the fuel tank 100 and in engagement with the spring 106 in a manner such that rotation of the second cap 105 varies the tension of the spring 106. The plate 107 is attached to the spring 106 and adapted to move under tension of the spring 106 in a direction such that fuel stored within the fuel tank 100 is pressurized.
[0007] The constructional features of the tank uses in gravity feed fuel injection system will be described in further detail. The fuel tank 100 comprises one inlet 102 to receive fuel, the first cap 103 is used to open and close the inlet 102. The fuel tank 100 also comprises a second cap 105. In an embodiment the second cap 105 may be a screw plug. The second cap 105 is in engagement with the spring 106. The plate 107 is located within the fuel tank 100 and attached to the spring 106. The plate 107 is guided by the spring 106 and seals the inner walls of the tank against fuel leakage. In other words the plate 107 creates a volume within the fuel tank 100 for storing fuel as disclosed in FIG. 1. A force balancer is provided in between the spring 106 and the plate 107. The force balancer ensures that the tension of the spring 106 is equally distributed onto the plate 107, and the plate 107 moves uniformly within the tank.
[0008] The working of the fuel tank 100 for pressurizing fuel stored in the fuel tank 100 will now be explained in further detail. Initially it is assumed that there is not fuel in the fuel tank 100. A user rotates the second cap 105. By doing so the tension in the spring 106 is relieved and the plate 107 moves within the tank so as to create volume for storing fuel. The user opens/ or rotates the first cap 103 of the fuel tank 100 in order to provide a path for fuel to enter the fuel tank 100. The first cap 103 is then closed to create an air tight seal for the fuel within the fuel tank 100. This ensures that the only available path for the fuel to flow out from the fuel tank 100 is through the low pressure pipe leading to the fuel filter and the metering unit. Once the fuel has been filled in the fuel tank 100, the second cap 105 is rotated. The rotation of the second cap 105, creates a certain amount of tension in the spring 106. This spring 106 then exerts tension/ force on the plate 107 via the force balancer 110. The force balancer 110, distributes the force/ tension onto the plate 107 equally. The tension is required in order to give the fluid a constant pre-pressure for filling the high pressure pump, through the gravity flow. As the plate 107 moves, the fluid is pressurized and flows through the outlet 104 to reach the high pressure pump via the metering unit. The above mentioned working example has been explained with respect to a spring 106. However, any other element, like bellows, that cause the plate 107 to traverse within the tank may be used, in lieu of spring 106.
[0009] FIG. 2 illustrates a gravity feed fuel injection system 200. The proposed gravity feed fuel injection system 200 comprises at least a fuel tank 100, a filter 202, a metering unit 204, a high pressure pump 206 and an injector 208. The fuel tank 100 comprises an inlet 102, outlet 104, and a first cap 103. A second cap 105 is located on the fuel tank 100 and in engagement with the spring 106 in a manner such that rotation of the second cap 105 varies the tension of the spring 106. The plate 107 is attached to the spring 106 and adapted to move under tension of the spring 106 in a direction such that fuel 108 stored within the fuel tank 100 is pressurized. The gravity feed fuel injection system 200 may be a common rail fuel injection system, employing single cylinder engines, multi-cylinder engines. The proposed gravity fuel injection system 200 may be used irrespective of the type of high pressure pump used. In the proposed fuel injection system the need for an electric feed pump is no longer required as the fuel is pressurized within the tank and supplied to the high pressure pump.
[00010] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention in terms of the type of spring used, material of the plate. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.