Claims:We Claim

1. A high pressure fuel pump (10), said high pressure fuel pump (10) comprising:
a housing (12);
a plunger (14) positioned within a barrel (16) of said housing (12), and adapted to reciprocate within the barrel (16) of said housing (12);
a first fuel gallery (17) defined on a first side of said housing (12), said first fuel gallery (17) adapted to channel fuel to the barrel (16) via a first cross feed supply path (18), said plunger (14) adapted to pressurize the channeled fuel and deliver it to an engine;
a second fuel gallery (20) defined on an opposite second side of said housing (12), said second fuel gallery (20) adapted to receive excess pressurized fuel from said barrel (16) via a second cross feed supply path (22), wherein the first fuel gallery (17) is independent of the second fuel gallery (20).

2. The high pressure fuel pump (10) in accordance with Claim 1 further comprising an Mprop in flow communication with said first fuel gallery (17), said Mprop adapted to deliver a metered quantity of pressurized fuel to said first fuel gallery (17).

3. The high pressure fuel pump (10) in accordance with Claim 1 further comprising a horizontal groove (26) defined through said plunger (14), the horizontal groove (26) defined through said plunger (14) aligned with the second cross feed supply path (22) defined through said housing (12) when said plunger (14) reaches its top dead center to facilitate discharging residual fuel that is present above the top dead center to the second fuel gallery (20) via the horizontal groove (26) that is defined through said plunger (14) and the second cross feed supply path (22) that is defined through said housing (12).

4. The high pressure fuel pump (10) in accordance with Claim 3 further comprising a vertical groove (28) defined through said plunger (14) and in flow communication with the horizontal groove (26) defined through said plunger (14) at a first end, and with a top portion of said plunger (14) at the opposite second end, the vertical groove (28) adapted to supply residual fuel that is present above the top dead center to the second fuel gallery (20) via the horizontal groove (26) defined through the plunger (14) and the second cross feed supply path (22) defined through said housing (12).
, 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] This invention relates to a high pressure fuel pump, and more specifically to a governing mechanism for the high pressure fuel pump.

Background of the invention
[0002] JP 2007138981 A describes providing a solenoid valve having the short axial length and a high pressure fuel pump using this valve. A stopper is superposed in the axial direction on a fixed core on the inner peripheral side of the fixed core. The stopper is positioned in the axial direction to the fixed core by being pushed in the axial direction against a step height formed on an inner peripheral wall of the fixed core, and projects a little to the opposed part side of a movable member from the fixed core side. When turning on current-carrying to a coil, an opposed part of the movable member is attracted to an attracting part of the fixed core. The stopper locks the opposed part attracted to the attracting part of the fixed core, and guides a rod of the movable member in the reciprocating direction. When a valve member is seated on a valve seat, communication of a fuel gallery with a pressurizing chamber is cut off.

Brief description of the accompanying drawing
[0003] Figure 1 illustrates a schematic diagram of a high pressure fuel pump illustrating a first fuel gallery and a second fuel gallery in one embodiment of the invention.

Detailed description of the embodiments
[0004] Figure 1 illustrates a schematic diagram of a high pressure fuel pump 10 in one embodiment of the invention. The high pressure fuel pump 10 comprises a housing 12, and a plunger 14 positioned within a barrel 16 of the housing 12, and adapted to reciprocate within the barrel 16 of the housing 12. The first fuel gallery 17 is defined on a first side of the housing 12, the first fuel gallery 17 adapted to channel fuel to the barrel 16 via a first cross feed supply path 18. The plunger 14 is adapted to pressurize the channeled fuel and deliver it to an engine. A second fuel gallery 20 is defined on an opposite second side of the housing 12, the second fuel gallery 20 adapted to receive excess pressurized fuel from the barrel 16 via a second cross feed supply path 22, wherein the first fuel gallery 17 is independent of the second fuel gallery 20.

[0005] The high pressure fuel pump 10 comprises a housing 12, and a plunger 14 that is positioned within a barrel 16 of the housing 12. In an exemplary embodiment, the plunger 14 is adapted to reciprocate within the barrel 16 of the housing 12, and delivers pressurized fuel from the high pressure fuel pump 10 to an engine. A first fuel gallery 17 is defined on a first side of the housing 12. The first fuel gallery 17 is adapted to channel fuel to the barrel 16 via a first cross feed supply path 18. Once the fuel is channeled to the barrel 16 from the first fuel gallery 17 via the first cross feed supply path 18, the plunger 14 is adapted to pressurize the channeled fuel in the barrel 16 and deliver it to an engine. A second fuel gallery 20 is axially spaced from the first fuel gallery 17, and is defined on the opposite second side of the housing 12. In the exemplary embodiment, the first fuel gallery 17 is independent of the second fuel gallery 20. Therefore, there does not exist any fuel communication between the fuel that is present in the first fuel gallery 17 and the fuel that is present in the second fuel gallery 20. The fuel in the first fuel gallery 17 cannot enter and flow out of the high pressure fuel pump 10 via the second fuel gallery 20 and vice versa.

[0006] Once the fuel in the barrel 16 is pressurized and delivered out of the high pressure fuel pump 12, the plunger 14 translates within the bore 16 of the high pressure fuel pump 10 until it reached the top dead center of the high pressure fuel pump 10. Once the plunger 14 reaches the top dead center of the high pressure fuel pump 10, most of the fuel that is required to be compressed and delivered is thereby delivered to the engine. The excess residual fuel that is present once the plunger 14 reaches the top dead center of the barrel 16 flows into the second fuel gallery 20 as will be explained in more detail below.

[0007] The high pressure fuel pump 10 comprises an Mprop (not shown) that is in flow communication with the first fuel gallery 17. The Mprop is adapted to deliver a metered quantity of pressurized fuel to the first fuel gallery 17. Therefore, the quantity of pressurized fuel that is delivered to the high pressure fuel pump 10 is limited and is dependent on the quantity of metered fuel that is supplied by the Mprop. Therefore, in the absence of the Mprop, the high pressure fuel pump 10 delivers a constant volume of pressurized fuel to the engine during each stroke of the plunger 14. However, with the introduction of the Mprop, the quantity of pressurized fuel that is delivered out of the high pressure fuel pump 10 is equal to the quantity of pressurized fuel that is required to be delivered to the engine based on the load that is acting on the engine, and which is supplied by the Mprop.

[0008] The high pressure fuel pump 10 comprises a vertical groove 28 that is defined through the plunger 14. More specifically, the vertical groove 28 is bored from a top portion of the plunger 14 through the plunger 14, and is adapted to supply residual fuel from the barrel 16 that is above the top portion of the plunger 14 to the second fuel gallery 20. The residual fuel is thereby transported out of the high pressure fuel pump 10 via the vertical groove 28. The high pressure fuel pump 10 further comprises a horizontal groove 26 that is defined through the plunger 14 and a second cross feed supply path 22 that is defined through the housing 12. When the plunger 14 reaches its top dead center, the horizontal groove 26 that is defined through the plunger 14 aligns with the second cross feed supply path 22 that is defined through the housing 12. Therefore, the residual fuel that is present above the top dead center is discharged to the second fuel gallery 20 via the vertical groove 28 that is defined in the plunger 14, the horizontal groove 26 that is defined through the plunger 14, and the second cross feed supply path 22 that is defined through the housing 12.

[0009] A working of the high pressure fuel pump 10 is described as an example. When the plunger 14 of the high pressure fuel pump 10 translates upwardly, it reaches its top dead center. When the plunger 14 of the high pressure fuel pump 10 reaches its top dead center, the horizontal groove 26 that is defined through the plunger 14 aligns with the second cross feed supply path 22 that is defined through the housing 12. Therein, the residual fuel that remains above the top dead center after the majority of the fuel is delivered from the high pressure fuel pump 12 is received in the engine flows through the vertical groove 28 that is defined in the plunger 14, then flows through the horizontal groove 26 that is defined through the plunger, then flows through the second cross feed supply path 22 that is defined through the housing 12, and is finally discharged into the second fuel gallery 20. From the second fuel gallery 20, the residual fuel is channeled back to the fuel tank. Because the first fuel gallery 17 and the second fuel gallery 20 are independent of each other, the residual fuel from the second fuel gallery 20 cannot flow into the first fuel gallery 17. Similarly, the fuel that is channeled into the barrel 16 of the high pressure fuel pump 10 via the first fuel gallery 17 cannot flow into the second fuel gallery 20. Therefore, the mixing of the fuel between the fuel entering into the high pressure fuel pump 10 via the first fuel gallery 17 with the fuel that is present in the second fuel gallery 20 is completely avoided.

[0010] It must be understood that the embodiments explained above are only illustrative and do not limit the scope of the disclosure. Many modifications in the embodiments with regard to dimensions of various components are envisaged and form a part of this invention. The scope of the invention is only limited by the scope of the claims.