Claims:We Claim:

1. A fuel injection pump (200), comprising at least:
a low pressure region (201) and a high pressure region (202), interconnected by at least one bore (203);
characterized in that

said fuel injection pump comprises one inlet (204) in flow communication with said low pressure region; and

one outlet (206) in flow communication with said high pressure region, wherein fuel entering said inlet reaches said outlet through said at least one bore after pressurization in said high pressure region.

2. The fuel injection pump of claim 1, wherein said outlet is the only single flow path available for flow communication between said high pressure region of said fuel injection pump and an accumulator.

3. The fuel injection pump of claim 1, wherein said outlet is the only single flow path available for flow communication between said high pressure region of said fuel injection pump and an injector.

4. The fuel injection pump of claim (2 and 3), wherein said outlet is not in flow communication with a fuel tank.

5. A fuel injection system (300), comprising at least:

a fuel tank (302);
a feed pump (304);
a fuel injection pump (200); and
a injector (306); characterized in that
a single flow path (307) ensures flow communication between said fuel injection pump (200) and said injector (306). , Description:Field of the invention
[0001] This invention relates to the field of a fuel injection pump in a fuel injection system.

Background of the invention
[0002] A fuel injection pump in fuel injection system, delivers pressurized fuel received from a feed pump, to an injector or accumulator. The fuel injection pump is a part of both low pressure circuit and high pressure circuit in the fuel injection system. The low pressure circuit comprises at least fuel tank, filter, feed pump, an overflow valve and a metering unit. The fuel injection pump has multiple bores (passages) for the fuel to flow into and out of the pump. Primary among them are the low pressure bore leading to the pressurizing chamber and the high pressure bore from the pressurizing chamber to the outlet of the fuel injection pump. Apart from these the fuel injection pump also has bores for regulating overflow and backflow quantity that return fuel back to the fuel tank. A bore in the fuel injection pump is generally created with the help of drilling operation and then closed through ball pressing. Drilling large number of bores in the fuel injection pump complicates the circuit in the fuel injection system. Hence, there is a need to simplify the low pressure circuit in the fuel injection pump.

Brief description of the accompanying drawing
[0003] Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:
[0004] FIG.1 illustrates a fuel injection pump in a fuel injection system as per the state of art; and
[0005] FIG. 2 illustrates a fuel injection pump; and
[0006] FIG. 3 illustrates a fuel injection system.

Detailed description of the embodiments
[0007] FIG.1 illustrates a fuel injection pump in a fuel injection system as per the state of art. The fuel injection system comprises a low pressure circuit and a high pressure circuit. The low pressure circuit comprises at least a fuel tank 102, a fuel filter 104, a feed pump 106. From the feed pump 106, the fuel reaches the inlet of the fuel injection pump 100 via a metering unit 105. The metering unit 105 controls the amount of fuel that needs to be supplied from the fuel injection pump to the accumulator/ or the injector. An overflow valve and backflow valve, regulates any excess quantity from the fuel injection back to the fuel tank via a backflow path. Hence, the fuel injection pump 100 in the state of art, comprises multiple outlets. One outlet reaching the accumulator/ or injector. While the other outlet from the fuel injection pump is in flow communication with the fuel tank through the backflow path 107.

[0008] FIG. 2 illustrates a fuel injection pump 200. The fuel injection pump 200 comprises a low pressure region 201 and a high pressure region 202, interconnected by at least one bore 203. The fuel injection pump 200 comprises one inlet 204 in flow communication with the low pressure region 201 and one outlet 206 in flow communication with said high pressure region 202, wherein fuel entering the inlet 204 reaches the outlet 206 through the bore 203 after pressurization in the high pressure region 202. The outlet 206 is the only single flow path available for flow communication between the high pressure region 202 of the fuel injection pump and an accumulator. The outlet 206 is the only single flow path available for flow communication between the high pressure region 202 of the fuel injection pump 200 and an injector. The outlet 206 is not in flow communication with a fuel tank.

[0009] The constructional details of the proposed fuel injection pump 200 will now be described in further detail. The fuel injection pump 200 has an inlet 204 that is in fuel communication with low pressure region 201. The fuel injection pump also comprises a bore 203. One end of the bore 203 is in communication with the inlet 204 and another end of the bore is in flow communication with pressurizing chamber. The part of the bore 203 from the inlet 204 of the fuel injection pump 200 up to the inlet of the pressurizing chamber is the low pressure bore 207. From the pressurizing chamber, the bore 203 leads to the outlet of the high pressure pump (also called as the high pressure bore 208) due to the fact that pressurized fuel from the pressurizing chamber flows through this high pressure bore 208 to reach the outlet 206 of the fuel injection pump 200. The outlet 206 of the fuel injection pump 200 is connected to a high pressure pipe (not shown). The high pressure pipe is connected to an accumulator or the injector. The proposed fuel injection pump is a simplified version, in comparison to the fuel injection pump 100 disclosed in state of art (FIG. 1). By having one inlet 204 and one outlet 206, the need for multiple bores in the fuel injection pump to account for overflow and back leak can avoided. Hence the need for a separate overflow valve and metering unit in the fuel injection system is not required anymore.

[00010] During working of the proposed fuel injection pump 200 mentioned above, fuel from the feed pump enters the inlet 204 of the fuel injection pump 200. From the inlet 204 the fuel flows through the low pressure bore 207 to reach the pressurizing chamber. The pressurized fuel enters the high pressure region 202 to reach the outlet 206 of the fuel injection pump 200. The outlet 206 is the only single flow path available for flow communication between said high pressure region 202 of said fuel injection pump 200 and an accumulator or the injector.

[00011] The complexity and therefore the cost of the fuel injection pump is less due to the elimination of the overflow valve, metering unit and bores in the fuel injection pump. For applications with not so severe load collective, e.g. the Indian market of passenger cars (3 and 4 cylinder) even the backflow of the pump to the tank can be eliminated. The invention can be used for all pump types (1, 2, 3, x plunger) where due to the load collective the heat situation of the pump is not critical.

[00012] FIG. 3 illustrates a fuel injection system. The proposed fuel injection system comprises at least a fuel tank (302), a feed pump (304), a fuel injection pump (200) and an injector (306). The fuel injection pump is characterized in having only a single flow path (307) in flow communication between the fuel injection pump and (200) the injector (306). Hence, the only available path for fuel to flow after reaching the inlet of the fuel injection path, is the path that leads to the injector (306). Also, the flow path (307) is the only available flow path for flow communication between fuel injection pump (200) and an accumulator. The backflow path 107 (as disclosed in detailed description of FIG.1) is not required anymore. Since the backflow path is eliminated, the need for a metering unit and overflow valve is not required anymore.

[00013] 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.