Claims:We Claim:

1. A high pressure fuel pump (10), said high pressure fuel pump (10) comprising at least:
a housing (12) having a recess adapted to accommodate a plunger (14) in said recess; characterized in that
a seal (20) located with reference to said housing (12) and said plunger (14) such that said plunger (14) reciprocates through said seal (20), wherein said seal (20) comprises at least two independent elements that are detachably coupled to each other.
2. The high pressure fuel pump (10) in accordance with Claim 1, wherein a first of said at least two independent elements comprises at least one projection (16) that is defined at its top surface, said at least one projection (16) fits into at least one groove (18) defined at a bottom of a second of said at least two independent elements.
3. The high pressure fuel pump (10) in accordance with Claim 1, wherein a first of said at least two independent elements includes a cavity (22) defined between its top surface and its bottom, said cavity (22) adapted to channel fuel from said housing (12).
4. The high pressure fuel pump (10) in accordance with Claim 1 wherein said plunger (14) reciprocates within said housing (12) such that fuel is channeled through a clearance defined between said housing (12) and said plunger (14).
5. The high pressure fuel pump (10) in accordance with Claim 1 wherein said seal (20) is connected to an inner sidewall of said housing (12).
6. The high pressure fuel pump (10) in accordance with Claim 1, further comprising a support plate (24) provided at an interface defined between said seal (20) and said housing (12) to prevent said seal (20) from expanding within a clearance defined between said plunger (14) and said housing (12).
7. A seal (20) for sealing a high pressure fuel pump (10), said seal (20) comprising:
a first element (26) and at least a second element (28), said at least a second element (28) detachably coupled to said first element (26) to facilitate sealing said high pressure fuel pump (10).
8. The seal (20) for sealing a high pressure fuel pump (10) in accordance with Claim 7, wherein said first element (26) comprises at least one projection 16 that is defined at its top surface, said at least one projection 16 fits into at least one groove 18 defined at a bottom of said second element (28).
9. The seal (20) for sealing a high pressure fuel pump (10) in accordance with Claim 7, wherein said first element (26) includes a cavity (22) defined between its top surface and its bottom, said cavity (22) adapted to channel fuel from a housing (12) of said high pressure fuel pump (10).
, Description:Field of the invention:

[0001] 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:

[0002] 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 oil in the oil sump. In addition, 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 oil or vice versa in the high pressure fuel pump, a sealing arrangement is required.

[0003] 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 is located to the inlet 24 to allow fuel to flow from the recess to the inlet 24.

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 shows a schematic view of a high pressure fuel pump; and

[0006] Figure 2 shows a schematic view of a seal in contact with a reciprocating piston of the high pressure fuel pump.

Detailed Description of the invention:

[0007] As shown in Figure 1, a high pressure fuel pump 10 is described. The high pressure fuel pump 10 comprises at least a housing 12 having a recess adapted to accommodate a plunger 14 in the recess. A seal 20 is located with reference to the housing 12 and the plunger 14 such that the plunger 14 reciprocates through the seal 20, wherein the seal 20 comprises at least two independent elements that are detachably coupled to each other.

[0008] In addition, a seal 20 for sealing a high pressure fuel pump 10 is described. The seal 20 comprises a first element 26 and at least a second element 28, the at least second element 28 detachably coupled to the first element 26 to facilitate sealing the high pressure fuel pump 10.

[0009] A plunger 14 is positioned within the housing 12 of the high pressure fuel pump 10, wherein the plunger 14 reciprocates within the housing 12. In an embodiment, the seal 20 is positioned within the housing 12. The plunger 14 reciprocates within a cavity defined within the seal 20 for sealing the high pressure fuel pump 10. 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.

[00010] The high pressure fuel pump 10 includes a seal 20. The seal 20 prevents fuel from mixing with lubricating oil from an oil sump that is positioned below the high pressure fuel pump 10. The seal 20 is provided in an annular space and housed within the housing 12. The housing 12 facilitates retaining the seal 20 in a press fit arrangement, thereby preventing movement of the seal 20 within the housing 12 when the plunger 14 reciprocates within the housing 12.

[00011] As shown in Figure 1, the seal 20 is provided on an inner periphery of the housing 12. The seal 20 has an outer surface that slidably and tightly contacts within the inner surface of the housing 12 and an inner surface that slidably and tightly contacts to the plunger 14 to facilitate sealing the plunger 14 within the housing 12 of the high pressure fuel pump 10.

[00012] The seal 20 has a cross section that is circular in shape and includes a cavity including the inner surface within which the plunger 14 is inserted thereto. As a material of the seal 20, PTFE (polytetrafluoroethylene) having good fuel resistance and high wear resistance may be employed. Alternatively, any material known in the art that facilitates providing a sealing arrangement between the seal 20 and the plunger 14 may be employed to seal the high pressure fuel pump 10.

[00013] The high pressure fuel pump 10 includes a support plate 24. The support plate 24 is provided between the seal 20 and the housing 12 to facilitate preventing the seal 20 from expanding within a clearance defined between the plunger 14 and the housing 12. Specifically, the support plate 24 is provided at the base portion of the seal 20 and forms a tight interface between the seal 20 and the housing 12. Moreover, the support plate 24 provides a rigid base on which the seal 20 can be seated to facilitate providing tight sealing contact between the support plate 24 and the seal 20.

[00014] As shown in Figure 2, the seal 20 is described. The plunger 14 is inserted within the seal 20 such that the seal 20 circumscribes the plunger 14. The seal 20 includes a first element 26 and at least a second element 28. The first element 26 is detachably coupled to the at least second element 28 to facilitate sealing the high pressure fuel pump 10. The first element 26 includes at least one projection 16 that is defined at its top surface. The at least second element 28 includes at least one groove 18 defined at its bottom. The at least one projection 16 fits within the at least one groove 18 such that the first element 26 may be detachably coupled to the at least second element 28. The at least one projection 16 fits within the at least one groove 18 in a press fit arrangement. Alternatively, the at least one projection 16 is coupled to the at least one groove 18 by means of a fastener. In an embodiment, two or more projections defined on the top surface of the first element 26 fits within two or more grooves defined at the bottom of the at least second element 28. Any number of elements may be coupled to one another as desired to constitute the seal 20.

[00015] The seal 20 includes a cavity 22 that is defined between the top surface of the first element 26 and the bottom of the first element 26. When fuel flows from the inlet of the high pressure fuel pump 10, the fuel flows through the clearance between the plunger 14 and the seal 20. Due to the hydrodynamic pressure of the fuel between the plunger 14 and the seal 20, the fuel enters into the cavity 22 from where it may be extracted thereto.

[00016] An operation of the high pressure fuel pump 10 is now described as an example. When the high pressure fuel pump 10 sucks fuel into the compression chamber, a portion of the fuel is channeled through the clearance between the housing 12 and the plunger 14. The fuel then flows through a clearance between the seal 20 and the plunger 14 and into the cavity 22. The excess fuel that does not flow into the cavity 22 flows downwardly and into any one of the cavities defined between the plunger 14 and the seal 20 from where it may be extracted. When it has been determined that the size of the seal 20 is insufficient to prevent the mixing of oil in fuel, the length of the seal 20 may be increased by coupling one or more elements to the existing elements to constitute the required length. Therefore, the seal 20 prevents fuel that flows from the high pressure fuel pump 10 from mixing with lubricating oil in the oil sump and vice versa.

[00017] The above described high pressure fuel pump 10 is cost effective and highly reliable. The seal 20 connected to the high pressure fuel pump 10 facilitates preventing fuel supplied to the high pressure fuel pump 10 from mixing with oil from the oil sump. 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. The modular nature of the seal 20 allows for easy assembly and disassembly of the various seal elements.

[00018] 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.