CLIAMS:We Claim:
1. A fuel injection pump (100), comprising at least
a housing (102) to accommodate a plunger, said plunger adapted to rotate within said housing (102) via a control rod (104), said fuel injection pump (100) characterized in having
a through hole (106) formed on said housing 102 of said fuel injection pump 100 in a manner such that said through hole 106 enables mechanical engagement of said control rod and said plunger within said housing 102; and
a guide member 108 having a first opening 110 and a second opening 112, said guide member 108 inserted in said through hole 106 in a manner such that said first opening 110 in said guide member 108 enables insertion of said control rod 104 into said guide member 108, said control rod 104 inserted in said guide member in a manner such that said control rod 104 is in mechanical engagement with said plunger.
2. The fuel injection pump 100 of claim 1, wherein length of said second opening 112 of said guide member 108 defines length of travel of said control rod 104.
3. The fuel injection pump 100 of claim 1, wherein said fuel injection pump 100 is a single cylinder fuel injection pump 100.
4. The fuel injection pump 100 of claim 1, wherein profile of said guide member 108 is complementary to the profile of said through hole 106. ,TagSPECI:Field of the invention
[0001] This invention relates to the field of fuel injection pump.
Background of the invention
[0002] A fuel injection pump delivers pressurized fuel to an injector via a high pressure pipe for injection into the engine cylinder. The subject of present invention is related to single and or /multi cylinder fuel injection pumps in which fuel is pressurized in the fuel injection pump due to the reciprocating motion of a plunger. The plunger is present within the housing of the fuel injection pump and rotates with the help of a control rod. A governor controls the movement of the control rod. In the existing state of art, the control rod is in mechanical engagement with the plunger, with the help of a boss through a regulating sleeve. A boss is a protrusion that is made available on the housing of the fuel injection pump. The boss is provided with a bore that accommodates the control rod. In order for the boss to be made integrated, the housing of the fuel injection pump has to be manufactured through casting process. This casting process leads to an increase in the cost of manufacturing a fuel injection pump. Hence there to simplify the design of the fuel injection pump.
[0003] Prior art patent application US5247917 discloses a fuel injection pump for internal combustion engines with a plurality of pump elements in which the fuel injection quantity is varied via a governor rod, which is supported in a U-shaped guide rail; according to the invention, this guide rail is loaded in its middle region by at least one spring element, in order to prevent transverse vibration of the governor rod.
Brief description of the accompanying drawing
[0004] Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:

[0005] FIG. 1 illustrates a fuel injection pump;
[0006] FIG. 2 illustrates a housing of the fuel injection pump; and
[0007] FIG. 3 illustrates a guide member of the fuel injection pump.
Detailed description of the embodiments
[0008] FIG. 1 illustrates a fuel injection pump 100. The fuel injection pump 100 performs two main functions. Firstly, compress fuel that is received from a fuel tank to high pressure and velocity, this high pressure fuel is then supplied to an injector or plurality of injectors for atomization of fuel and for the combustion to happen in the engine cylinder. Secondly, the fuel injection pump 100 also meters the quantity of fuel that needs to be delivered to the injector via a high pressure pipe based upon the demand. The former function is achieved by virtue of fuel entering the pump chamber, and the fuel getting compressed due to the upward motion of the plunger caused due to rotation of the cam shaft. The latter function, which is, metering of fuel, is achieved by selectively rotating the plunger in a manner so as to block and/ or unblock the inlet of fuel into the pump chamber and also block and/ or unblock a port that is used to relieve excess fuel if any from the pump chamber. The excess fuel may be used for lubrication of the pump components or relieved back to the fuel tank. The rotation of the plunger happens with the help of a control rod 104 whose movement is controlled by a governor based upon the demand from the driver. The subject of interest here is about the mechanism through which control rod 104 is guided in the housing 102 of the fuel injection pump 100 and in turn engages with the plunger through a regulating sleeve of the fuel injection pump 100, the same will now be described in further detail.
[0009] The fuel injection pump 100 comprises at least a housing 102 to accommodate a plunger, the plunger is adapted to rotate within the housing 102 via the control rod 104. The fuel injection pump 100 may be a single and or multi-cylinder fuel injection pump 100. The fuel injection pump 100 is characterized in having a through hole 106 formed on the housing 102 of the fuel injection pump 100 in a manner such that the through hole 106 enables mechanical engagement of the control rod 104 and the plunger within the housing 102, and a guide member 108 having a first opening 110 and a second opening 112 , the guide member 108 is inserted in the hole 106 in a manner such that the first opening 110 in the guide member 108 enables insertion of the control rod 104 into the guide member 108, the control rod is inserted in the guide member in a manner such that the control rod 104 is in mechanical engagement with the plunger. The second opening 112 of the guide member 108 opens into at least a part of the hole 106 formed on the housing 102. This overlapping helps the control rod 104 to be in mechanical engagement with the plunger. A gear ring or a sleeve may be used to mechanically connect the control rod 104 and the plunger.
[00010] As mentioned earlier, the reciprocating plunger also rotates around its vertical axis to change the effective stroke length, which provides for the metering function. The rotation of the plunger happens with the help of the control rod 104. The control rod 104 is attached to the governor via a series of linkages. When the driver demands more power, these linkages transmit the demand to the pump metering system via the control rod 104 motion. Therefore the linear movement of the control rod 104 is transmitted to the plunger in the form of a rotational movement that changes the relative position of the plunger helix to, either be in fluid communication with the inlet port or the port through which excess fuel is relieved from the fuel injection pump 100.
[00011] FIG. 2 illustrates a housing 102 of the fuel injection pump 100. The housing 102 of the fuel injection pump 100 is machined from a single bar of material. The through hole 106 is formed on the housing 102 of the fuel injection pump 100. The through hole 106 may be formed on the housing 102, through drilling, milling or through any other suitable material removal process. The profile of the through hole 106 is such that the guide member 108 can be inserter in the through hole. The position of the through hole 106 on the housing 102 of the fuel injection pump 100 is such that it enables that the control rod 104 to be in contact with the plunger located in the housing 102.
[00012] FIG. 3 illustrates a guide member 108 of the fuel injection pump 100. The profile of the guide member 108 is complementary to the profile of the through hole 106. The guide member 108 has a first opening 110 for inserting the control rod 104 into the guide member 108. The length of the second opening 112 of the guide member 108 defines length of travel of the control rod 104 which in turn controls the rotation of the plunger within the fuel injection pump 100. The control rod 104 can reciprocate along the length of the second opening 112 and also mechanically engage with the plunger of the fuel injection pump 100 through the second opening 112.
[00013] During working of the proposed fuel injection pump 100, fuel is first received in the pumping chamber of the fuel injection pump. Fuel from the fuel gallery enters into the cavity on top of the plunger through a series of ports. The upward motion of the plunger resulting from the camshaft rotation continues to push the fuel atop the plunger and upwards towards a delivery valve. As the plunger continues its upward movement, it eventually blocks the ports and thus traps the fuel and forces it to unseat the delivery valve, the fuel then flows into the high pressure pipe, and proceeds on to reach the injector. The plunger is machined with a slot and a helix. The helix faces the inlet port of the fuel injection pump 100 when fuel needs to be taken into the pumping chamber for pressurization. During pressurization, the position of the helix needs to be in a manner such that it blocks the inlet port. This is achieved by rotating the plunger with the help of the control rod 104 that is positioned and guided through the proposed guide member 108. The guide member 108 fits into the housing of the fuel injection pump in a way such that mechanical engagement is possible between the control rod 104 and the plunger through the through hole 106. The control rod 104 movement is dependent on the position of the governor, and is in turn based upon the demand for speed and power output. The control rod 104 is linked to the governor with help of linkages. Based upon the position of the governor the control rod 104 moves in a manner so as to rotate the plunger, and in turn cause (a) the fuel to be taken into the pumping chamber, (b) fuel to be pressurized in the pump chamber by rotating the plunger and changing the orientation of the slot and helix and (c) relieve excess fuel if any from the pumping chamber.
[00014] 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 type of the fuel injection pump used and the profile of the hole. 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.