Claims:We Claim:
1. A fuel injection system (100), said fuel injection system (100) comprising at least a fuel tank (102) located upstream to a filter (104) , a high pressure pump (106), a metering unit (108), an overflow valve (110) and a common rail (112); characterized in that:
the outlet (114) from said overflow valve (110) is in flow communication with inlet of said high pressure pump (106).

2. The fuel injection system 100 of claim 1, wherein said overflow valve is a throttle valve.

3. The fuel injection system 100 of claim 1, wherein said overflow valve is a mechanically operated valve.
, Description:Complete Specification:

The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed.
Field of the invention
[0001]This invention relates to the field of fuel injection system.

Background of the invention
[0002]In a fuel injection system fuel from a fuel tank is supplied to pump via an electric feed pump and filter. Fuel is then supplied to metering unit and to maintain pressure in front of the metering unit excess fuel is passes via overflow valve to tank. When metering valve is closed, certain amount of fuel leaks to cylinder head region. This situation is not desired therefore, a zero delivery throttle is provided to allow leaked fuel to pass to tank via backflow.

Brief description of the accompanying drawing
[0003] Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:

[0004] FIG. 1 a fuel injection system.

Detailed description of the embodiments
[0005] FIG. 1 a fuel injection system 100. The fuel injection system 100 comprises at least a fuel tank 102 located upstream to a filter 104, a high pressure pump 106, a metering unit 108, an overflow valve and a common rail 112. The fuel injection system 100 in characterized in that, the outlet 114 from the overflow valve is in flow communication with the inlet of high pressure pump 106. The overflow valve may be a throttle valve.

[0006]The working of the fuel injection system 100 will be explained in further detail. Fuel from fuel tank 102 flows through the fuel filter 104 and reaches the inlet high pressure pump 106. Before reaching the inlet of the high pressure pump 106, the fuel flows via the metering unit 108. The function of the metering unit 108 is to regulate the amount of fuel that reaches the inlet of the high pressure pump 106. When the metering unit 108 is closed a small quantity of fuel leaks through the clearances and the excess fuel leaked is sent back to the tank. In order to avoid additional pumping of fuel from the tank and back via the overflow valve, in the proposed fuel injection system 100 the outlet 114 is routed to the inlet of the high pressure pump. The leaked fuel will now flow through a throttle to ensure pressure difference in order to avoid fuel flow in the reverse direction.

[0007]With the use of the above mentioned fuel injection system 100 it is now possible to conserve energy of the fuel injection system 100 that is utilized to pump fuel from the tank to the high pressure pump 106.

[0008]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 fuel injection system. 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.