Claims:We Claim:
1. An injector (104) for a common rail injection system (100); said injector (104) comprising at least:
an injector housing (208);
a piston (201) adapted to reciprocate inside said injector housing (208);
a nozzle body (202) and a needle (203) located in the nozzle body (202);
characterized in that said injector (104) comprising:
at least one slot (205) provided in said injector housing (208);
a guide bush (204), said guide bush (204) located in said injector (104) in a manner such that at least a part of the guide bush (204) is accommodated in said nozzle body (202) and at least a part (206) of the guide bush (204) is accommodated in said at least one slot (205) in said injector housing (208), said guide bush (204) comprising at least one portion extending from said part (206) of said guide bush (204) located in said slot (205) in a manner such that movement of said guide bush (204) is restricted.
2. The injector (104) as claimed in claim 1, wherein said at least one portion extending from said part (206) of said guide bush (204) is located along the outer circumference of said guide bush (204).
3. The injector (104) as claimed in claim 1, wherein said guide bush (204) comprising an axial hole in a manner such that at least a part of said piston (201) and at least a part of said needle (203) are accommodated in said guide bush (204).
4. The injector (104) as claimed in claim 2, wherein said axial hole in said guide bush (204) has varying diameter in dependence of the diameter of said piston (201) and said needle (203).
5. The injector (104) as claimed in claim 1, wherein said at least one portion extending from said part (206) of said guide bush (204) is adapted to restrict the rotational movement of said guide bush (204). , Description:Field of the invention:
[0001] The invention here relates to an injector for common rail injection system.
Background of the invention:
[0002] The common rail injection system in particular gives the freedom to reduce exhaust emissions especially to lower engine noise. The particular design of the common rail allows the engine and the injection system to be matched to each other in best possible way. In the common rail injection systems, the fuel is pressurized up to say 2000 bar for the injection process. The main advantage of the common rail injection system is its ability to vary injection pressure and timing. In common rail injection system 100, the fuel is atomized and injected into the combustion chamber with high injection pressure to reduce the exhaust gas emission during the operation of the vehicle. Also the quantity of fuel injected is very closely metered.
[0003] The patent application DE -102009000282 explains fuel injector, particularly common rail injector, for injecting fuel in combustion chamber of internal combustion engine has nozzle needle which is adjusted between closed and open position. Here the fuel injector has a nozzle needle which is adjusted between a closed position and an open position releasing the flow of fuel through multiple injection holes provided in a nozzle body. The fuel injector has multiple flow channels which are arranged at a distance in the nozzle body in the circumferential direction. The flow channels are limited by a guide bush arranged in a nozzle body. The fuel injector has multiple flow channels which are arranged at a distance in a nozzle body in the circumferential direction where the flow channels are limited by a guide bush arranged in a nozzle body and hence ensures optimized nozzle needle guide with simple manufacturing and minimized tilting inclination of the nozzle needle, and prevents unequal mass and secondary mass and secondary speed distributions at the injection holes.

Brief Description of the accompanying drawings
[0004] An exemplifying embodiment of the invention is explained in principle below with reference to the drawings. The drawings are,
[0005] Figure 1 illustrates an overview of a common rail system 100 according to an embodiment of an invention.
[0006] Figure 2 illustrates a view of an injector 104 for common rail injection system according to an embodiment of an invention.
Detailed Description of the invention:
[0007] Figure 1 illustrates an overview of the common rail injection system 100 consists of following components a low pressure system 101, a high pressure system 102 and the electronic control unit 105. In a low pressure system 101, the fuel is at low pressure stored in a fuel tank. In a high pressure system 102, the highly pressurized fuel is sent to the rail 103 from where the fuel flows to the injector 104 based on the signal received from the electronic control unit 105.
[0008] An injector in general comprises at least a magnet, an armature, a piston, and a nozzle body with a nozzle needle accommodated in the nozzle body. The fuel is received from the rail to a passage into the injector. Based on the requirement and signal received from the electronic control unit, the magnets get activated and attract the armature. The movement of the armature results in the movement of the piston and the nozzle needle in the nozzle. Due to the movement of the armature, the pressure exerted by the nozzle needle at the seat of the nozzle needle reduces while fuel which is present at the tip of the nozzle needle exerts a higher pressure which causes the nozzle needle to be displaced from its seat. When the nozzle needle is displaced from its seat the injector injects the fuel. In accordance with this disclosure a guide bush is fitted in between the piston and the nozzle needle to guide the movement of the piston and the nozzle needle.
[0009] The constructional details of the injector in accordance with this disclosure will be further explained with reference to figure 2. The injector 104 comprises at least an injector housing 208, a piston 201 and a nozzle body 202. A needle 203 is located in the nozzle body 202. The piston 201 is adapted to reciprocate inside the injector housing 208. The needle 203 in the nozzle body 202 is adapted to operate based on the reciprocation of the piston 201. The injector 104 further characterized in a manner such as to comprise at least one slot 205 provided in the injector housing 208 and a guide bush 204. The guide bush 204 is located in the injector 104 in a manner such that at least a part of the guide bush 204 is accommodated in the nozzle body 202 and at least a part 206 of the guide bush 204 is accommodated in at least one slot 205 in the injector housing 208. The guide bush 204 comprising at least one portion extending from the part 206 of the guide bush 204 located in the slot 205 in a manner such that movement of the guide bush 204 is restricted.
[00010] In the injector 104, at least one portion extending from the part 206 of the guide bush is located along the outer circumference of the guide bush 204.
[00011] The guide bush 204 comprises an axial hole in a manner such that at least a part of the piston 201 and at least a part of the needle 203 are accommodated in guide bush 204. The axial hole in the guide bush has varying diameter in dependence of the diameter of the piston201 and the needle 203.
[00012] In the injector 104, at least one portion extending from said part 206 of the guide bush is adapted to restrict the rotational movement of the guide bush 204. In the injector 104, the movement of the guide bush 204 is restricted in the slot 205 inside the injector 104. The reciprocation of the guide bush 204 is only in the slot 205 so that the guide bush 204 reciprocates inside the injector 104 for the common rail injection system 100.
[00013] Also, the guide bush 204 is located in between the piston 201 and the needle 203 of the nozzle 202 so that the guide bush 204 guide the movement of the piston 201 and the needle 203 of the nozzle 202.
[00014] In the common rail injection system 100, during the movement of the piston 201 or the reciprocation of the piston 201 along the axis, the driving torque from the spring rotates the guide bush 204 which in turn rotates the nozzle needle 203 which causes the nozzle 202 and nozzle needle 203 seat wear and results in the drift and affects the quantity of an injector 104. The guide bush 204 in accordance with this disclosure is designed to arrest degree of freedom with the help of the slot 205 and guide the movement of piston 201 and needle 203 and minimize the seat wear which in turn will increase the life of the components of the injector 104 and also increases the reliability of the injector 104. So when there is a driving torque from spring, the guide bush 204 tends to rotate but at least one part 206 of the guide bush 204 is located in the slot 205, so the rotation will not happen and rotation of the nozzle needle 203 is locked. Likewise the wear and tear of the nozzle 202 in the injector 104 is reduced.
[00015] It must be understood that the embodiments explained in the above detailed description in only illustrative and does not limit the scope of this invention. The scope of this invention is limited only by the scope of the claims. Many modification and changes in the embodiments aforementioned are envisaged and are within the scope of this invention.