CLIAMS:We Claim:
1. A common rail 106 in a fuel injection system, comprising
at least an inlet port 105 in flow communication with a high pressure pump 104, plurality of outlet ports 107, at least one said outlet ports 107 in flow communication with one injector 108, and a return line port 109 in flow communication with a return line path 110 via a connector 111, said return line path 110 in flow communication with a fuel tank, characterized in that
said connector 111 is made integrated with said common rail 106.
2. The common rail 106 of claim 1, wherein said connector 111 has a bore 112 and an edge break 113.
3. The common rail 106 of claim 1, wherein said connector 111 is integrated with the common rail through forging.
4. The common rail 106 of claim 1, wherein flow of fuel from said return line port 109 is controlled by a pressure limiting valve located on said connector 111 of said common rail 106.
5. The common rail 106 of claim 1, wherein flow of fuel from said return line port 109 is controlled by a pressure control valve located on said connector 111 of said common rail 106. ,TagSPECI:The following specification particularly describes the invention and the manner in which it is to be performed.

Field of the Invention
[001] The invention relates to a fuel injection system of the type employing a common rail.

Background of the invention
[002] Fuel reservoir injection systems also called as common rail systems are known in principle. A distinction is made between common rail systems with a quantity-regulated high-pressure pump (known as CP3 systems), in which a pressure reduction in the fuel pressure reservoir (common rail) is possible only via the injection control quantity and leakage, and common rail systems in which a pressure limiting valve or pressure control value on the high-pressure side is used to lower the system pressure. The subject of the present invention is the latter type of system, that is, one with a pressure limiting valve or pressure control value for lowering the system pressure.

[003] A common rail in a fuel injection system, supplies fuel at high pressure, received from a fuel injection pump, to at least one injector. The injector injects the fuel into a cylinder for combustion. The injection of fuel into the cylinder happens based upon the demand for power as programmed in ECU. If the demand for power is more, then fuel at high pressure is injected into the cylinder, conversely if the demand for power is less, then the excess pressure is relieved through fuel return path back to the fuel tank. This is done in order to maintain stability of the common rail and deliver the fuel at required pressure into the cylinder. The fuel return path is in constant flow communication with the common rail through a connector. Generally the connector is made available in the form of a separate component; then the connector is then screwed / pressed-in onto the common rail. Because of the assembly of connector with fuel reservoir, problems exists, in particular in the sealing area between the connector and common rail leading low pressure leakage of fuel. Other inadequacies of the known systems resulting in high cost are: assembly cost of connector onto common rail, testing setup & cost for leakage detection in low pressure circuit. In order to reduce the costs involved in manufacturing and assembly, and testing there is a need to modify the assembly of the common rail and the connector

[004] Prior art patent application US6675774 a fuel injection system for internal combustion engines, in particular Diesel engines, having a fuel reservoir which is supplied from a high-pressure pump and supplies fuel to a number of injectors corresponding to the number of cylinders of the engine, and has a pressure limiting valve which is connected sealingly to the fuel reservoir, the pressure limiting valve having a valve housing, a high-pressure region, a low-pressure region, a valve seat oriented toward the inlet, an axially displaceable valve body, and a valve spring urging the valve body in the direction of the valve seat. The pressure limiting valve is integrated--at least partially--with the fuel reservoir, in such a way that at least the valve seat and the valve body are spatially associated with the fuel reservoir, and the seal sealing off the pressure limiting valve from the fuel reservoir is associated with the low-pressure region of the pressure limiting valve.

Brief description of the accompanying drawing
[005] Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:
[006] Fig 1 Illustrates a circuit diagram of a fuel injection system; and
[007] Fig 2 illustrates the common rail used in the fuel injection system.

Detailed description of the embodiments
[008] Fig 1 Illustrates a circuit diagram of a fuel injection system. The fuel injection system comprises a fuel tank 100 with an electric feed pump 102, a fuel filter 103, a high pressure pump 104, a common rail 106 and the injector 108. A series of supply lines connect each of the components of the fuel injection system for efficient transport of fuel. Fuel from the fuel tank 100 passes through the fuel filter 103 and reaches the inlet of the high pressure pump 104 where the fuel is pressurized. Pressurized fuel from the high pressure pump 104 is sent to the common rail 106 for injection through the injector 108. The components of the fuel injection system are controlled through an Electronic control unit (ECU). The fuel injection system comprises a low pressure circuit and the high pressure circuit. The part of the circuit upstream of the high pressure pump 104 is the low pressure circuit and the part of the circuit downstream from the high pressure pump 104 is the high pressure circuit. The high pressure circuit will be described in further detail.

[009] The high pressure circuit comprises the common rail 106 that receives fuel at high pressure from the high pressure pump 104. The common rail 106 stores the high pressure fuel and delivers it to the injector for injection into the cylinders.

[0010] FIG. 2 illustrates the common rail 106 in the fuel injection system. The common rail 106 comprises an inlet port 105 in flow communication with a high pressure pump, plurality of outlet ports 107, at least one of the outlet ports 107 is in flow communication with one injector. A return line port 109 is in flow communication with a return line path 110 via a connector 111. The return line path 110 is in flow communication with a fuel tank. A connector 111 is made integrated with the common rail 106. The connector 111 establishes a flow connection between the return line port 109 on the common rail 106 and the return line path 110. The fuel flows through the bore 112 of the connector 111 into the return line path 110.The connector 111 may be integrated with the common rail through forging operation. The connector 111 and the common rail 106 may be machined from a single stock of material. The connector 111 may be provided with a bore 112 and an edge break 113. The edge break 113 may be in the form of a chamfer or a fillet. The edge break 113 is the surface through which fuel from the common rail enters into the connector 111. In an embodiment the connector 111 may be provided with a bore 112 and without any edge break.

[0011] Initially the common rail 106, receives high pressure fuel from the high pressure pump. The fuel from the common rail 106 flows to the injector, for injection into the cylinders. The injector injects fuel as long as the pressure in the rail is greater than the pressure at end of the injector. When the demand for fuel to be injected is less than the actual pressure at which fuel is being currently injected, then the pressure at which fuel is available in the common rail 106 has to be reduced to prevent damage to the common rail 106. This is achieved by having the return line port 109. The return line port 109 may be controlled by a pressure limiting valve located on the connector 111 of the common rail 106 or a pressure control valve located on the connector 111 of the common rail 106. The pressure is determined based on factors like, engine speed, engine load, temperature, and the like. The fuel accumulated in the common rail 106 flows back to the fuel tank 100 through the return line path 109. Since the connector 111 relieves the pressure in the common rail 106 it is also called as a low pressure connector.

[0012] 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 number of outlet ports on the common rail. 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.