Claims:We Claim:
1. A fuel injector (200), comprising:
at least one fuel return path (202) in flow communication with a backflow connector (204) located on said fuel injector 200; and
said backflow connector (204) in flow communication with a fuel tank (208) via a pipe (206); characterized in that
a valve (210) located in said backflow connector (204) in manner so as to throttle un-injected fuel received in said fuel return path (202) of said fuel injector (200) and send said fuel back to said fuel tank (208).

2. The fuel injector (200) of claim 1, wherein said valve (210) is integrated with said backflow connector 204.

3. The fuel injector (200) of claim 1, wherein said valve (210) is at least one chosen from a group comprising at least a ball valve, a pin type valve, a pintle valve.

4. The fuel injector (200) claim 1, wherein said valve (210) is a one-way valve. , Description:Field of the invention
[0001] This invention relates to the field of a fuel injector.

Background of the invention

[0002] A fuel injector is a part of both low pressure circuit and high pressure circuit in a fuel injection system. The high pressure circuit comprises at least a high pressure pump, accumulator, and the injector adapted to receive pressurized fuel from the accumulator. The injector opens and closes for injecting fuel into the engine cylinder based upon signals from the ECU. The un-injected volume of fuel that is left over in the injector, due to factors like closing of the injector and leakage, needs to be relieved from the injector to avoid secondary injection and also un-necessary pressure build up in the injector so as to prevent damage to the components of the injector. Located in the injector is a back flow connector that opens into a pipe leading to a fuel tank. The pressure at which un-injected fuel is relieved back to the fuel tank is generally referred to as back pressure. The back pressure depends upon at least one of the following parameters comprising dimensions of the pipe, material of the pipe. In the current state of art, the back pressure of fuel, is maintained to an acceptable level by having a check valve/ non-return valve in the fuel return pipe of the low pressure circuit. In order to have a robust functional behavior of the injector over lifetime of the injector there is a need to make the backpressure of the fuel independent of the pipe characteristics.

[0003] FIG. 1 illustrates a backflow pipe for a fuel injector 100 used in the state of art. The backflow pipe 106 connects the backflow connector 104 of the injector 100 to the fuel tank 108. The un-injected fuel from the injector 100, is sent back to the fuel tank 108 through the back flow pipe 106. The backflow pipe 106, has a one-way valve (check/ non-return valve) 102 that allows the fuel to flow through the backflow pipe in one direction only, i.e from the backflow connector to the fuel tank and not the other way and helps maintain the required back pressure for the injector. It is observed that, in addition to the check/non-return valve, the diameter of the pipe and pipe characteristic influence the back pressure to the injector 100.

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:

Detailed description of the embodiments

[0005] FIG. 2 illustrates a fuel injector 200. The fuel injector 200 comprises at least one fuel return path 202 in flow communication with a backflow connector 204 located on the fuel injector 200. The backflow connector 204 is in flow communication with a fuel tank 208 via a pipe 206. A valve 210 is located in the backflow connector 204 in manner so as to throttle un-injected fuel received in the fuel return path 202 of the fuel injector 200 and send the fuel back to the fuel tank 208. In an embodiment the valve is integrated with the backflow connector 204. The valve may be a one-way valve. The valve is at least one chosen from a group comprising at least a ball valve, a pin type valve, a pintle valve.

[0006] The constructional details of the fuel injector 200 with the proposed valve will be described in further detail. The injector has a nozzle 203 through which fuel is injected into the engine cylinder. The opening and closing of nozzle happens with the help of signals received from electronic control unit (ECU) based upon the demand. A fuel return path 202 is located within the injector in a manner such that un-injected fuel from nozzles can flow to the backflow connector 204. The backflow connector 204 is located in the region where the injector 200 opens into the low pressure circuit. The valve is located in the backflow connector 204. The valve helps in maintaining the back pressure of the fuel injector 200.

[0007] The working of fuel injector 200 with the valve integrated on the backflow connector 204 will now be explained in detail with reference to FIG. 2. The injector 200, receives fuel for injection into the engine cylinder, from the accumulator. The ECU through signals to the injector, decides the quantity of fuel that needs to be injected into the engine cylinder. The fuel injector 200 opens and closes, during fuel injection into the engine cylinder. The un-injected volume fuel needs relieved back to the fuel tank as backflow leakage. In addition to un-injected fuel, the backflow leakage also includes any leakage through clearances of the injector and control quantity use for opening the fuel injector 200. The un-injected fuel flows through the fuel return path 202 to reach the backflow connector 204 of the fuel injector 200. The valve that is located in the backflow connector 204 throttles un-injected fuel and maintains the required back pressure to the fuel injector 200, the fuel now flows through the pipe to reach the fuel tank. Since, the valve is a one-way valve, flow of fuel is only possible from the backflow connector 204 of the fuel injector 200 to the fuel tank 210. As the fuel is throttled in the backflow connector 204 itself, the need for a separate valve in the pipe 206 is not required anymore (in comparison to FIG.1 in state of art). The pressure at which fuel flows through the pipe is less than the pressure at which the fuel is available in the fuel injector 200. This prevents damage to the pipe 206, the pipe 206 being a part of low pressure circuit of the fuel injection system.

[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 valve 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.