Claims:We Claim:
1. A fuel injection system (100), said system comprising at least:
a fuel tank (102);
a feed pump (104) located downstream to said fuel tank 102;
a high pressure pump (106) located downstream to said feed pump (104) and adapted to supply fuel to anyone of rail (107) and an injector (108) via a first flow path (109), characterized in that :
a solenoid (110) located along a second flow path (111), said solenoid (110) adapted to enable flow communication between said high pressure pump (106) and said fuel tank (102).

2. The fuel injection system 100 of claim 1, wherein said solenoid 110 is controlled by an electronic control unit.
, Description:Field of the invention
[0001]This invention relates to the field of fuel injection system.

Background of the invention
[0002]A fuel injection system is used to supply pressurized fuel for combustion in the engine cylinder. The components of the fuel injection system for enabling injection of fuel into the engine cylinder are fuel tank, a feed pump, a high pressure pump with metering unit and the common rail that stores fuel under pressure before it is injected into the engine cylinder with the help of fuel injectors. In order to maintain the stability of the components of the fuel injection system there is need to maintain the pressure of fuel within safety as prescribed for normal working of the fuel injection system. This is achieved by providing relief path in the components like the common rail, the fuel injection pump and the feed pump. In case of malfunction or error in the components of the fuel injection system, the high pressure pump is not able to build up sufficient pressure to force open the relief path for flow of fuel.

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 illustrates a fuel injection system. The fuel injection system 100 comprises a fuel tank 102, a feed pump 104 located downstream to the fuel tank 102. A high pressure pump 106 is located downstream to the feed pump 104 and adapted to supply fuel to anyone of rail 107 and an injector 108 via a first flow path 109. A solenoid 110 is located along a second flow path 111, the solenoid 110 is adapted to enable flow communication between the high pressure pump 106 and the fuel tank 102. The solenoid 110 is controlled by an electronic control unit.

[0006]The working of the fuel injection system 100 will be explained in further detail. The fuel injection system 100 is used to deliver pressurized fuel into the engine cylinder for combustion. The fuel tank 102 stores fuel and allows fuel to flow via a pipe into the feed pump 104. The function of the feed pump 104 is to enable fuel to flow into the high pressure pump 106 via the metering unit. The metering unit ensures that the quantity of fuel reaching the high pressure pump 106 matches the demand of fuel as required by the rail 107. The high pressure pump 106 pressurizes the fuel before the fuel reaches the rail 107 for injection into the engine cylinder via the first flow path 109. The solenoid 110 is located along the second flow path 111, the solenoid 110 is adapted to enable flow communication between the high pressure pump and the fuel tank 102. The solenoid 110 may be controlled by an electronic control unit.

[0007]The electronic control unit performs the following functions, namely, monitor the fuel required to be injected into the engine in response to demand from the user of the vehicle. This is done by monitoring the quantity of fuel with respect to the engine demand. Any deviation from the above monitoring of quantity with respect to demand indicates an error in the metering unit. In case of error in the metering unit, the electronic control unit actuates the solenoid 110, the actuation of solenoid 110 causes a part of the fuel from the high pressure pump 106 to flow back to the fuel tank 102.

[0008] By using the above mentioned solenoid 110 in the second flow path 111 of the fuel injection pump it is now possible the flow valves like zero delivery throttle, and overflow valve that is used in the high pressure pump 106 thereby resulting in cost savings. The solenoid can also be used as a redundant metering unit for rail pressure control in case of the failure of the meeting unit.

[0009] ‘Adapted’ or ‘arranged’, in the context of the instant disclosure, refers to the technical capability or the technical capacity of a component, in relation to which the term ‘adapted’ or ‘arranged’ is used, to carry out or executed a specified action or actions, upon the requirement of the specified action or actions to be carried out or executed. Moreover, the usage of the term ‘adapted’ or ‘arranged’ here, is in reference with the normal technical capability or technical capacity of the component, imparted by the design or the structure or the composition of the component, and not in reference with any special or extraneous capability or capacity, beyond the scope of the normal technical capability or technical capacity. Therefore there is a need to address this problem.

[0010]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 solenoid used. 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.