Claims:We Claim:
1. A fuel pump (100) for a vehicle, the fuel pump (100) comprising a housing (101) and at least a plunger adapted to reciprocate in said housing (101), a fuel inlet (102) in the said housing (101) providing a fluid communication path with an inlet valve (103), a leak-off groove (104) providing a fluid communication path between the inlet valve (103) and a plunger sealing chamber (1053), the plunger sealing chamber (1053) having a plunger sealing ring (1054), characterized in that fuel pump (100):
an undercut (1051) in the pump housing (101) on top of the plunger sealing chamber (1053) to enable fluid communication between the leak off groove and a plunger clearance, a washer (1052) positioned between the plunger sealing ring (1054) and the undercut (1051).

2. The fuel pump (100) for a vehicle as claimed in claim 1, wherein a mesh is placed inside the undercut (1051).
, Description:Complete Specification:
The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed

Field of the invention
[0001] The present disclosure relates to a fuel pump for a vehicle. More specifically it relates to a plug-in type high pressure fuel pump.

Background of the invention
[0002] Plunger sealing ring is used in plug in type of fuel pumps to separate oil and fuel (fluid separation). It is observed that during operation of the plunger owing to its up and down movement or due to presence of some frictional component in the fuel such as metallic flakes, the plunger sealing is dislocated and affects the desired functioning of the pump and the fuel system. This can lead to closure of a leak off groove and also the plunger sealing ring itself can act as a plunger in the plunger sealing chamber leading to pressure oscillation at the pump inlet adversely affecting fuel pressure control in the system.

[0003] Patent application CN109386418A titled “Plunger Pump and High Pressure Fuel Pump” discloses a plunger pump. The plunger pump comprises a plunger sleeve, a plunger, a sealing ring sleeve and a plunger sealing ring, wherein a plunger cavity and a sealing ring chamber are defined in the plunger sleeve; the plunger axially reciprocates in the plunger cavity; the sealing ring sleeve is arranged in the sealing ring chamber, and axial constraining force capable of keeping the sealing ring sleeve in the sealing ring chamber is generated through interference fit formed between the sealing ring sleeve and the corresponding part of the plunger sleeve; the plunger sealing ring is embedded into the sealing ring sleeve, and the plunger penetrates through plunger sealing ring and is sealed by the sealing ring sleeve.

Brief description of the accompanying drawings
[0004] An embodiment of the invention is described with reference to the following accompanying drawings:
[0005] Figure 1 depicts a fuel pump (100) for a vehicle;
[0006] Figure 2 depicts a portion (105a) of the fuel pump (100) in accordance with a first embodiment; and
[0007] Figure 3 depicts a portion (105b) of the fuel pump (100) in accordance with a second embodiment.

Detailed description of the drawings
[0008] Figure 1 depicts a fuel pump (100) for a vehicle. The fuel pump (100) forms a part of fuel supply circuit for an internal combustion engine. It is usually placed upstream from a common rail and downstream from a fuel filter. The fuel entering the fuel pump (100) from fuel filter is not pressurized, the function of the fuel pump (100) is to pressurize this fuel and deliver it to the common rail.

[0009] The fuel pump (100) in accordance with this invention comprises a housing (101) and at least a plunger (106) adapted to reciprocate in said housing (101). A fuel inlet (102) is provided in the said housing (101) that provides a fluid communication path with an inlet valve (103). A leak-off groove (104) provides a fluid communication path between the inlet valve (103) and a plunger sealing chamber (1053). The plunger sealing chamber (1053) has at least a plunger sealing ring (1054).

[0010] The fuel pump (100) is characterized by an undercut (1051) in the pump housing (101) on top of the plunger sealing chamber (1053) that enable fluid communication between the leak off groove (104) and a plunger clearance. Further a washer (1052) is positioned between the plunger sealing ring (1054) and the undercut (1051). In an embodiment of the present disclosure a mesh is placed inside the undercut (1051).

[0011] In the conventional fuel pumps, the plunger sealing ring (1054) is placed to prevent/reduce oil and fuel mixing in the plunger sealing chamber (1053). The plunger sealing ring (1054) is pressed into the pump housing (101) with interference fit. The gap between the plunger sealing ring (1054) top and housing (101) acts as a connection between the plunger clearance and the leak off groove (104).

[0012] Figure 2 depicts a portion (105a) of the fuel pump (100) in accordance with a first embodiment of the proposed fuel pump (100). In the proposed design, a special arrangement is made in which the Plunger sealing ring (1054) is placed between two washers, an additional washer (1052) on the top and one at the bottom to restrain the axial movement of the plunger sealing ring (1054). The plunger sealing chamber (1053) is dimensioned in such a way that it will still have a small clearance to allow expansion and contraction of the Plunger sealing ring (1054).

[0013] The most important non-limiting feature of this fuel is the special under cut is made in the housing (101) to connect the plunger clearance and leak off groove (104), which will enable continuation of the function of the leak off groove (104), ensuring limited oil and fuel mixing and providing a path of leak off few to return to the fuel inlet (102).

[0014] Figure 3 depicts a portion (105b) of the fuel pump (100) in accordance with a second embodiment, wherein in addition to the features of the first embodiment a mesh is placed inside the undercut (1051). The function of the mesh is to prevent the coarse particles in the fuel from entering the plunger seal chamber, which creates friction with the plunger sealing ring (1054) causing it to move up and down. The mesh can be of different executions like laser bored metal filter which can be either press fitted or screw type.

[0015] This idea to develop a fuel pump (100) with the above mentioned features helps arrest the movement of the plunger sealing ring (1054). The fuel pump (100) with the proposed design also helps to eliminate fuel pressure oscillation at the pump inlet which can be caused by the dislodged plunger sealing ring (1054).

[0016] It must be understood that the embodiments explained in the above detailed description are only illustrative and do not limit the scope of this invention. Any modification a fuel pump (100) for a vehicle are envisaged and form a part of this invention. The scope of this invention is limited only by the claims.