Claims:We claim:
1. A fuel injector (10), said fuel injector (10) comprising at least:
- an injector body (110);
- a valve piston (102); and
- a nozzle (20), said nozzle (20) comprising at least a nozzle body (104) and a nozzle needle (106); characterized in that a guide hole (108) located at the operative top surface of the nozzle needle (106) where said guide hole (108) is provided in a manner such that the guide hole (108) seats operative bottom part of said valve piston (102).
2. The fuel injector (10) as claimed in claim 1, wherein said guide hole (108) has a uniform diameter.
3. The fuel injector (10) as claimed in claim 1, wherein said guide hole (108) has varying diameter.
, Description:Complete specification: The following specification particularly describes the invention and the manner in which it is to be performed. 
Field of the invention:
[0001] The invention relates to a fuel injector and particularly relates the nozzle of the fuel injector.

Background of the Invention:
[0002] A person skilled in art would be aware that many version of fuel injectors are already known. However, some basic components in a fuel injector are always present. Following are some of the basic components of any fuel injector known in the state of the art viz the injector body components, the magnet group components, electrical connector components, nozzle module components and the like. With regard to this disclosure we will specifically focus on the nozzle of the injector and specifically on the nozzle needle and valve piston alignment of a fuel injector.
[0003] Currently existing designs of fuel injectors the assembly of valve piston and nozzle needle may lead to misalignment of the two with respect to their nozzle needle guide axis. If the nozzle needle and valve piston axial alignment are not concentric, the assembly may lead to one side wear on nozzle body bore guidance in these injectors. This is caused when the valve piston and the nozzle needle guide axis are not necessarily concentric which lead to radial force on nozzle needle guide resulting in one sided wear of nozzle body guidance. This in turn can change injector characteristics, thereby resulting in injection quantity drift and high backflow.
[0004] Therefore, there exists a need for a solution to ensure the concentric alignment of valve piston and nozzle needle in a fuel injector, as described in this disclosure.

Brief Description of Drawings:
[0005] An embodiment of the disclosure is described with reference to the following accompanying drawings,
[0006] Fig. 1 illustrates a fuel injector, according to an embodiment of the present invention;
[0007] Fig. 2 illustrates a nozzle of a fuel injector according to an embodiment of the present invention; and
[0008] Fig. 3 illustrates a nozzle of a fuel injector according to an embodiment of the present invention.

Detailed description of the embodiments:
[0009] Fig 1 illustrates a fuel injector (10), according to an embodiment of the present invention. The fuel injector (10) comprises of at least an injector body (110), a valve piston (102) and a nozzle (20).
[0010] Fig. 2 illustrates a nozzle (20) of the fuel injector (10) according to an embodiment of the present invention. The nozzle (20) comprising at least a nozzle body (104) and a nozzle needle (106).
[0011] The invention as disclosed here is further characterized by a guide hole (108) located at the operative top surface of the nozzle needle (106). The guide hole (108) is provided in a manner such that the guide hole (108) seats operative bottom part of said valve piston (102).
[0012] In one embodiment of the invention, guide hole (108) has a uniform diameter, whereas in another embodiment, the guide hole (108) may have a varying diameter. Additionally to ensure perfect seating of the nozzle, the diameter of the guide hole (108) will always be greater than the diameter of the valve piston (102).
[0013] The introduction of guide hole (108) as described herein can aid to improve the concentricity of valve piston (102) and nozzle needle (106) of the fuel injector (10). Additionally the valve piston (102) will seat perfectly inside it, thereby ensuring that the valve piston (102) and nozzle needle (106) alignment.
[0014] The guide hole (108) is provided such that the piston step diameter is extended to accommodate at nozzle needle guide hole. Therefore, the guide hole (108) accommodate the piston seating on top surface of the needle (106).
[0015] Provisioning of the guide hole (108) on the nozzle will ensure that the axis of the valve piston (102) and nozzle needle (106) will be concentric. As a result of which there will no resultant force acting on needle.
[0016] Additionally the guide hole (108) can significantly reduce the wear on nozzle guide bore and thereby maintain the characteristics like injection quality drift and backflow of the fuel injector (10) for longer duration.
[0017] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. 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.