Field of the invention

The present invention relates to a fuel injection pump for an internal combustion engine.

Background of the invention
The internal combustion engines are shut off by stopping the fuel flow from fuel injection pump. Specifically, in diesel engines, a mechanical governor is generally used, which is adapted for preventing fuel flow from the fuel injection pump when the engine needs to be stopped.

To stop the engine whenever required, a governor lever is operated manually for stopping the flow of fuel. Such manual operation may not be desirable. Hence, the fuel injection pumps were provided with electrical valves to shut off fuel supply to the fuel injection pump. The US patent 4565170 describes one such fuel injection system. An electric shut off valve is provided in a fuel line connecting a pumping unit and a fuel injection pump.

Advantages of the present invention
An advantage of the present invention is, during cranking of the internal combustion engine, the unwanted drawing off of the fuel from a pump gallery of the fuel injection pump is prevented. Also sufficient fuel pressure is retained in fuel circuit while supplying fuel during engine cranking.

Brief description of the accompanying drawings

Figure 1 illustrates working of a fuel injection pump during engine cranking in accordance with an embodiment of the present invention; and Figure 2 illustrates working of the fuel injection pump during engine shut off mode in accordance with an embodiment of the present invention.

Detailed description of the invention
Hgure 1 illustrates working of a fuel injection pump 100 during engine cranking in accordance with an embodiment of the present invention. A fuel tank 102 is provided with combustible fuel to be supplied for an internal combustion engine 104. A pumping unit 106, supplies fuel to the fuel gallery 108 of the fuel injection pump 100. In accordance with the present embodiment, during cranking of the internal combustion engine 104, an additional electric shut off valve 116 is kept in ON or open position for the fuel from the pumping unit 106 to be transferred to the fuel injection pump 100. A main electric shut off valve 114 is kept in OFF or closed position during cranking of the internal combustion engine 104, performed to prevent fuel transfer from the fuel gallery 108 of the fuel injection pump 100 to the pumping unit 106. In an exemplary embodiment, under certain conditions, for example during switching ON of the internal combustion engine 104 and the fuel injection pump 100 after a brief stop or OFF, the fuel gallery 108 may be approximately empty. Hence, the pumping unit 106 must be prevented from drawing off the fuel from the gallery 108 of the fuel injection pump 100. An overflow valve 120 is provided at an overflow outlet of the fuel injection pump 100. When the fuel gallery 108 of the fuel injection pump 100 is full, the fuel is purged out through an overflow line 118 to the fuel tank 102. Overflow valve 120 also prevents fuel suction from fuel tank 102 through fuel line 118 during stopping of internal combustion engine 104.

Figure 2 illustrates working of the fuel injection pump 100 during engine shut off mode in accordance with an embodiment of the present invention. In accordance with the present embodiment, positions of the main electric shut off valve 114 and the additional electric shut off valve 116 are changed to control flow of the fuel to and from the fuel injection pump 100. The positions of the valves 116 and 114 are adjusted in light of the internal combustion engine 104 being directed towards shut off mode. During the shut off of the internal combustion engine 104, the main electric shut off valve 114 is changed to ON or open position. When the valve 114 is in ON position, the pumping unit 106 is adapted to empty the gallery 108 by drawing off the fuel from the fuel injection pump 100. For example, the fuel from the fuel gallery 108 is temporarily stored in a fuel draw off line 111. Further, the additional electric shut off valve 116 is changed to OFF or closed position. Hence, the fuel supply to the fuel injection pump 100 is prevented. This leads to fuel cut-off in the fuel circuit and the internal combustion engine 104 is shut off.

Numerous modifications and variations of the present invention are possible which can be envisaged by the person skilled in the art. The scope of the present invention is to be interpreted only through claims appended herein.

WE CLAIM:

1. A fuel injection pump (100) for an internal combustion engine (104), comprising:

a pumping unit (106) mounted on the fuel injection pump (100); and

characterized in that

said fuel injection pump (100) comprising a fuel draw-off line (112) connecting an inlet of said pumping unit (106) and an outlet of said fuel injection pump (100), said fuel draw-off line (112) comprising a main electric shut off valve (114) preventing drawing off the fuel from said fuel injection pump (100) while cranking said internal combustion engine (104).

2. The fuel injection pump (100) in accordance with claim 1, wherein the main electric shut off valve (114) comprises an ON position and an OFF position.

3. The fuel injection pump (100) in accordance with claim 2, wherein the main electric shut off valve (114) is in said OFF position during cranking of the internal combustion engine (104).

4. The fuel injection pump (100) in accordance with claim 2, wherein the main electric shut off valve (114) is in said ON position during shutting off of the internal combustion engine (104).