Field of the invention
[0001]This invention relates to the field of fuel injection pump.
Background of the invention
[0002]. A fuel injection pump is used to deliver pressurized fuel to an injector/common rail. Fuel is received into the fuel injection pump via an inlet. In the fuel injection pump the fuel enters the pressurizing chamber where it is pressurized. The pressurization happens with the help of a reciprocating plunger 104, the plunger 104 receives drive from a cam via the roller tappet. The roller tappet rotates with respect to a pin. The roller tappet receives rotary motion from the cam and transfers the same to the plunger 104. The roller tappet is located within the housing. The interfaces of the roller tappet, like the end face is subject to wear. In case the amount of wear is more, it may lead to failure of roller tappet. Hence there is need to avoid wear of roller tappet.
[0003] Prior art patent application IN201717039154 relates to a roller tappet for a piston pump for supporting a reciprocating pump piston on a cam or an eccentric of a drive shaft, comprising a tappet body and a hollow cylindrical roller that is partly received in a frontal recess of the tappet body and is rotatably mounted on a pin directly or indirectly via a bearing bush, so that between the roller and the pin or between the roller and the bearing bush a radial bearing gap is formed to which a lubricating medium can be supplied via a bore that is formed in the tappet body and leads into the recess. According to the invention, the roller, in the region of its outer circumferential surface, in the region of its inner circumferential surface and/or in the region of at least one end face, has a geometry that influences the flow of the lubricating medium.

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:
[0005] FIG. 1 illustrates a fuel injection pump.
Detailed description of the embodiments
[0006] FIG. 1 illustrates a fuel injection pump 100. The fuel injection pump 100 comprises a housing 102 accommodating a plunger 104. The plunger 104 receives drive from a cam shaft via a cylindrical roller tappet 106. At least a first end face 108 of the roller tappet 106 comprises a circular groove 112 for receiving lubricating oil from an engine in order to lubricate the first end face 108 of the cylindrical roller tappet 106. The cylindrical roller tappet 106 comprises a second end face 110, the second end face 110 comprises a circular groove 114.
[0007]The construction of the cylindrical roller tappet 106 in the fuel injection pump 100 will be explained in further detail. For the purpose of better understanding, the construction of the fuel injection pump 100 will be explained first followed by the construction of roller tappet 106. The fuel injection pump 100 disclosed herein is used to pressurize fuel received from the fuel tank. The fuel enters the pressurizing chamber in the fuel injection pump 100. The pressurization happens with the help of a plunger 104 that is mounted within the housing 102 of the pump. The plunger 104 receives drive from roller tappet 106 that is driven by a cam (not shown). The construction of roller tappet 106 will be explained in further detail. The cylindrical roller tappet 106 is mounted on the cam. A roller pin 105, transfers the motion from the cam to the roller

tappet 106. The roller tappet 106 comprises a first end face 108 and a second end face 110. The first end face 108 and second end face 110 comprises a groove (112 and 114) for receiving lubricating oil. The groove (112 and 114) may be axially aligned with respect to the flow path 116
[0008]The working of the roller tappet 106 in the fuel injection pump 100 will be explained in further detail. The function of the roller tappet 106 is to transfer rotary motion from the cam to the plunger 104. As the cam rotates, the roller pin 105 receives the rotary motion from the cam and transfers the rotary motion to the roller tappet 106. The rotation of the roller tappet 106 provides drive to the plunger 104. Since the roller tappet 106 rotates continuously the end faces, that is, the first end face 108 and the second end face 110 are subjected to wear because of interface with the housing 102 of the fuel injection pump 100 and the roller pin 105. Hence, the end faces require lubrication.
[0009]The lubrication of the end faces is achieved by providing a circular groove (112 and 114) for receiving lubricating oil. The circular groove (112 and 114) is provided on both the first end face 108 and the second end face 110 of the roller tappet 106. The circular groove (112 and 114) receives lubricating oil from a flow path 116. The circulation of lubricating oil happens during working of the engine. The lubricating oil from the engine, reaches the flow path 116, the flow path 116 is designed in a manner such that, a volume of lubricating oil is directed towards the first end face 108, while remaining volume of lubricating oil is directed towards the second end face 110. In other words the flow path 116 branches in a manner so as to enable the lubricating oil to reach the first end face 108 and the second end face 110.

[0010]Consider the case in which the lubricating oil reaches the first end face 108. The circular groove 112 on the first end face 108 receives the lubricating oil from the flow path 116. Since the roller tappet 106 is rotating, the lubricating oil flows throughout the groove and lubricates the first end face 108. The circular groove 112 helps in lubricating the entire region in the first end face 108. This ensures that there is no region along the first end face 108 that is devoid of lubrication. Once the lubricating oil completes lubrication of the first end face 108, the lubricating oil is collected in a tank which may be recirculated for further lubrication requirements. By providing a groove (112 and 114) on the first end face 108 and the second end face 112 it is now possible to lubricate the surface area of the roller tappet and hence reduce friction.
[0011]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 fuel injection pump 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.

CLAIMS
We Claim:
1. A fuel injection pump 100, said pump comprising:
a housing 102 accommodating a plunger 104;
said plunger 104 receiving drive from a cam shaft via a cylindrical
roller tappet 106; characterized in that:
at least a first end face 108 of said roller tappet 106 comprising
a circular groove 112 for receiving lubricating oil.
2. The fuel injection pump 100 of claim 1, wherein said roller tappet 106 comprises a second end face 110, said second end face 110 comprises a circular groove 114.
3. The fuel injection pump 100 of claims 1 and 2, wherein said circular groove (112 and 114) receives said lubricating oil from a flow path 116.
4. The fuel injection pump 100 of claims 3, wherein said groove (112 and 114) is axially aligned with respect to said flow path 116.