CLIAMS:We Claim:
1. A high pressure fuel pump (10), said high pressure fuel pump (10) comprising:
a housing (12) having a bore adapted to accommodate a plunger (14) in said bore;
a flange (20) having a recess (17) and a hole, said flange (20) fitted to said housing (12) and adapted to accommodate said plunger (14) in said hole;
a seal (16) located in said recess (17) of said flange (20) and in contact with said plunger (14); characterized in that
said seal (16) comprises a first lobe (28) and a second lobe (30), said first lobe (28) and said second lobe (30) connected by a stem (32) in a manner such that a space (18) is defined between said first lobe (28) and said second lobe (30), said space (18) between said first lobe (28) and said second lobe (30) stores fluid leaking from either side of said first lobe (28) and said second lobe (30).
2. The high pressure fuel pump (10) in accordance with Claim 1, wherein a first passageway (22) extends from an inner surface of said flange (20) to an outer surface of said flange (20) to allow leaked fluid to flow from said space (18) out of said high pressure fuel pump (10).
3. The high pressure fuel pump (10) in accordance with Claim 1, wherein a second passageway (52) extends from an inner surface of said housing (12) to an outer surface of said housing (12) to allow leaked fluid to flow out of said high pressure fuel pump (10).
4. The high pressure fuel pump (10) in accordance with Claims 1 and 2, wherein said first passageway (22) and second passageway (52) are in flow communication with each other.
5. The high pressure fuel pump (10) in accordance with Claim 1, wherein said leaked fluid comprises fuel and lubrication oil leaking from either side of said first lobe (28) and said second lobe (30).
6. The high pressure fuel pump (10) in accordance with Claim 1, wherein said seal (16) includes a plurality of spring elements (42) disposed within said seal (16) to facilitate maintaining sealing contact between said seal (16) and said plunger (14).
7. The high pressure fuel pump (10) in accordance with Claim 1, wherein said seal (16) includes a plurality of serrations defined on the outer surface of said seal (16), said plurality of serrations facilitates maintaining sealing contact between said seal (16), said plunger (14), and said flange (20). ,TagSPECI:The following specification particularly describes the invention and the manner in which it is to be performed.

Field of the invention:
[001] This invention relates to a high pressure fuel pump and specifically to an apparatus for sealing the high pressure fuel pump.

Background of the invention:
[002] Fuel is channelled to a high pressure fuel pump where it is pressurized and supplied to a high pressure common rail. Fuel channelled to the high pressure fuel pump is supplied to a cylindrical bore where it is pressurized by a reciprocating piston. Due to a clearance that exists between a housing of the high pressure fuel pump and the reciprocating piston, fuel flows through the clearance. The fuel then flows into an oil sump that is positioned below the high pressure fuel pump, thereby diluting the lubrication oil in the oil sump. In addition, lubrication oil from the oil sump may flow into the cylindrical bore through the clearance between the housing of the high pressure fuel pump and the reciprocating piston where it mixes with the fuel in the cylindrical bore. In order to prevent fuel from mixing with the lubrication oil or vice versa in the high pressure fuel pump, a sealing arrangement is required.

[003] Indian Patent Application Number 3909/CHE/2014 describes a high pressure fuel pump 10. The high pressure fuel pump 10 comprises a housing 12 having a plurality of recesses adapted to accommodate an inlet 24, an outlet, and a plunger 14 in the plurality of recesses. A guide element 30 is located in one of the plurality of recesses such that the plunger 14 reciprocates through the guide element 30. A seal 20 is located with reference to the guide element 30 and the plunger 14 such that the plunger 14 reciprocates through the seal 20. A fuel passageway 22 extends from the recess in which the guide element 30 is located to the inlet 24 of the high pressure fuel pump 10 to allow fuel to flow from the recess to the inlet 24 of the high pressure fuel pump 10.

Brief description of the accompanying drawings
[004] An exemplifying embodiment of the invention is explained in principle below with reference to the drawings. The drawings are:

[005] Figure 1 shows a schematic view of a seal located in a high pressure fuel pump.

Detailed Description of the invention:
[006] As shown in Figure 1, a high pressure fuel pump 10 is described. The high pressure fuel pump 10 comprises a housing 12 having a bore adapted to accommodate a plunger 14 in the bore. A flange 20 has a recess 17 and a hole, the flange 20 fitted to the housing 12 and adapted to accommodate the plunger 14 in the hole. A seal 16 is located in the recess 17 of the flange 20 and in contact with the plunger 14. The seal 16 comprises a first lobe 28 and a second lobe 30. The first lobe 28 and the second lobe 30 are connected by a stem 32 in a manner such that a space 18 is defined between the first lobe 28 and the second lobe 30. The space 18 between the first lobe 28 and the second lobe 30 stores fluid leaking from either side of the first lobe 28 and the second lobe 30.

[007] The high pressure fuel pump 10 includes a housing 12. The housing 12 includes a compression chamber for sucking fuel from a suction port (not shown). The plunger 14 is positioned within the compression chamber to reciprocate and pressurize fuel for delivery through a fuel outlet supply path. The seal 16 is located in a recess 17 of the flange 20 and is in contact with the plunger 14.

[008] The high pressure fuel pump 10 has a seal 16. The seal 16 prevents the fuel from mixing with lubrication oil that is present in a lubrication oil sump positioned below the high pressure fuel pump 10. Moreover, the seal 16 prevents the lubrication oil in the lubrication oil sump from mixing with the fuel in the high pressure fuel pump 10. The seal 16 includes a first lobe 28 and a second lobe 30 that is positioned below the first lobe 28. A space 18 is defined below the first lobe 28 and above the second lobe 30. The space 18 stores fuel that is channeled between the first lobe 28 and the plunger 14. Similarly, the space 18 stores lubrication oil that is channeled between the second lobe 30 and the plunger 14. A stem 32 connects the first lobe 28 and the second lobe 30.

[009] As shown in Figure 1, at least a portion of the outer surface of the seal 16 is in contact with the inner surface of the flange 20 and at least a portion of the outer surface of the seal 16 is in contact with the plunger 14 to facilitate sealing the plunger 14 within the flange 20 of the high pressure fuel pump 10.

[0010] The seal 16 includes a hole within which the plunger 14 is inserted thereto. The seal 16 includes a plurality of U-shaped spring members 42 disposed within the seal 16. Each of the U-shaped spring members 42 is inserted within the seal 16 such that each U-shaped spring member exerts a tensile force against an inner surface and an outer surface of the seal 16. Specifically, at least a portion of the outer surface of the seal 16 compresses against the flange 20 while at least a portion of the outer surface of the seal 16 compresses against the plunger 14 to facilitate providing a tight fit between the seal 16 and the plunger 14 respectively. The seal 16 includes a plurality of serrations that grip against the plunger 14 thereby providing a tight fit between the seal 16 and the plunger 14. An outer surface of the seal 16 includes a plurality of serrations that facilitates providing a tight press fit between the seal 16 and the flange 20. The serrations defined on the outer surface of the seal 16 provide flexibility of the plunger 14 to move across the seal 16 and reduces fuel and lubricating oil leakage to the recess 18, thereby improving the sealing characteristics between the seal 16 and the plunger 14.

[0011] The seal 16 has a cross section that is circular in shape and includes a hole within an inner surface in which the plunger 14 is inserted thereto. As a material of the seal 16, any material known in the art that facilitates providing a sealing arrangement between the seal 16 and the plunger 14 may be used to seal the high pressure fuel pump 10.

[0012] A first passageway 22 extends from an inner surface of the flange (20) to an outer surface of the flange 20 to allow leaked fluid to flow from the space (18) out of said high pressure fuel pump 10. The first passageway 22 channels the leaked fuel between the first lobe 28 and the plunger 14 and leaked lubrication oil between the second lobe 30 and the plunger 14. A second passageway 52 extends from an inner surface of the housing 12 to an outer surface of the housing 12. The first passageway 22 and second passageway 52 are in flow communication with each other. The second passageway 52 facilitates channeling the leaked fuel and leaked lubrication oil from the outlet of the flange 20 to the outlet of the high pressure fuel pump 10. A vacuum pump is coupled to an outlet of the second passageway 52 and channels leaked fuel and leaked lubrication oil through the first passageway 22 to the outlet of the high pressure fuel pump 10.

[0013] An operation of the high pressure fuel pump 10 is now described as an example. During operation of the high pressure fuel pump 10, a portion of the fuel is channeled due to the leakage between the first lobe 28 and the plunger 14. The fuel then flows through the space 18 defined between the first lobe 28 and the second lobe 30. Similarly the space 18 stores lubrication oil that is channeled due to the leakage between the second lobe 30 and the plunger 14. The first passageway 22 facilitates leaked fuel and lubrication oil from being channeled from the space 18 to the outlet of the high pressure fuel pump 10 via the first passageway in the flange 20 and the second passageway in the housing of the high pressure fuel pump. A vacuum pump connected to the second passageway 52 sucks the leaked fuel and lubrication oil through the passageway 22 out of the high pressure fuel pump 10. Therefore, the seal 16 prevents fuel that is flowing to the high pressure fuel pump 10 from mixing with lubricating oil in the oil sump and vice versa.

[0014] The above described high pressure fuel pump 10 is cost effective and highly reliable. The seal 16 connected to the high pressure fuel pump 10 facilitates preventing fuel supplied to the high pressure fuel pump 10 from mixing with lubricating oil from the oil sump and vice versa. Moreover, the modular nature of each sub-system of the high pressure fuel pump 10 facilitates easy disassembly and replacement of individual system components as required.

[0015] It must be understood that the embodiments explained in the above detailed description is 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.