CLIAMS:I claim:
1. A fuel injection pump (10) to supply fuel into an engine, said fuel injection pump (10) comprising :
a plunger (12) adapted to reciprocate within a barrel (14) to suck said fuel through an inlet (22) and expel said fuel through an outlet (23) ;
characterized in said fuel injection pump (10);
a groove (20) on the head (21) of said plunger(12), a slope of said groove (20) provides a dynamic injection timing at a partial load (26(a)) or a full load (26(b)) operating condition.
2. The fuel injection pump (10) claimed in claim (1), wherein said dynamic injection timing is varied based on a configuration of said groove (20).
3. The fuel injection pump (10) claimed in claim (1), wherein a deep edge of said groove is placed near to a stop groove (16) in a retardation mode.
4. The fuel injection pump (10) claimed in claim (1), wherein said deep edge of said groove (20) is placed away from said stop groove (16) in an advanced mode.
,TagSPECI:Field of the invention
[001] This invention relates to a fuel injection pump to supply fuel into an engine.
Background of the invention
[002] In an internal combustion engine using diesel as a fuel, a fuel injection pump compresses the fuel into high pressure and delivers the fuel to an injector installed at a combustion chamber. An injection device for compressing and delivering the fuel includes a plunger and a barrel. The injection device compresses and delivers the fuel when the plunger serving as a piston reciprocates in the barrel serving as a cylinder. Internal combustion engines are controlled in many different ways to provide acceptable driving comfort during all operating conditions. Some methods use engine output or torque control, where the actual engine torque is controlled to a desired engine torque through an output adjusting device, such as with an electronic throttle, ignition timing, or various other devices.
[003] Many techniques are known in the state of art working of a fuel injection pump to supply fuel into an engine.
[004] US patent application 20130015274 discloses an injection system of a fuel injection pump having a plunger comprising a release groove and a control edge, performs a reciprocating slide motion in the axial direction inside of the plunger chamber of a barrel for compressing fuel. A damping groove formed in the upper-part outer circumference of the control edge meets the spill port in advance to form the fine flow of fuel from the plunger chamber to the spill port .

[005] Brief description of the accompanying drawings
[006] An exemplifying embodiment of the invention is disclosed in detail in the description and illustrated in the accompanying drawings:
[007] Figure 1 illustrates a schematic diagram of a fuel injection pump according to one embodiment of the invention;
[008] Figure 2 illustrates a schematic diagram of a plunger in a retardation mode; and
[009] Figure 3 illustrates a schematic diagram of a plunger in an advanced mode.
Detailed description of the invention:
[0010] Figure 1 illustrates a schematic diagram of a fuel injection pump 10 to supply fuel into an engine according to one embodiment of the invention. The fuel injection pump 10 comprises a plunger 12 adapted to move reciprocally within a barrel 14 to suck the fuel through an inlet 22 and expel the fuel through an outlet 23. The fuel injection pump 10 also comprises a groove 20 on a plunger head 21 of the plunger 12. A slope of the groove 20 provides dynamic injection timing at a partial load or a full load operating condition. The slope of the groove 20 is a rate of change of a pre stroke parameter in dependence with a load.
[0011] The plunger 12 present in the barrel 14 is provided with a stop groove 16 which connects the plunger head 21 to a control helix 18. The control helix 18 controls the amount of fuel injection. The amount of fuel that is injected is controlled by the rotation of the plunger 12 which in turn is controlled by a governor unit and a cam (not shown). The fuel delivery can be controlled by varying an effective stroke. The control rack (not shown) controls the plunger 12 movement such that the control helix 18 changes the point at which the effective delivery stroke ends. Based on the engine load, the amount of fuel injected by pump will be decided by the control rack and the governor unit. The calibration of the fuel injection pump 10 ensures the position of control helix 18 to deliver the required amount. The effective stroke will ensure the complete lift of the plunger 12 thus by delivering the fuel.

[0012] Figure 2 illustrates a plunger 12 and the configuration of the groove 20 in a retardation mode.
[0013] Figure 3 illustrates a plunger 12 and the configuration of the groove 20 in an advanced mode.
[0014] The groove 20 is formed on the plunger head 21.In the retardation mode, the configuration of the groove 20 is made such a way that the starting point 30 (a) is placed near to the stop groove 16. The deep edge 30(b) of the groove 20 is placed near to the start point 30 (a) of the groove 20.The end point 30(c)of the groove 20 is placed away from the stop groove 16 as shown in figure 2. The slope of the groove changes with respect to the starting point 30(a) and the end point 30 (b) of the groove 20. The start point 30(a), end point 30(b) and slope of groove can be made in such a way that full load (100%) 26(b) will be calibrated near a flat edge of the slope ie., a portion of groove 20 away from the stop groove16. The deep edge 30(b) of the groove 20 will be nearer to stop groove 16 and lower loads 26(a) will be operating using deep edge 30(b) of groove 20 by ensuring the control rack position.
[0015] In the advance mode, the configuration of the groove 20 is made such a way that the starting point 30(a) of the groove 20 is placed close to the stop groove 16 and the deep edge 30 (b) of the groove 20 is placed near to the end point 30(c) of the groove 20.The deep edge 30(b) and the end point 30(c) of the groove 20 is placed away from the stop groove 16 as shown in figure 3.The dynamic injection timing of the fuel can be varied based on the configuration of the groove 20. The start point 30(a), the end point 30(c) and slope of the groove 20 will be made such that, the operating point of full load 26(b) will be positioned in deeper edge 30(b) of the groove 20.
[0016] Prestroke adjustment of the plunger 12 is used to determine the advancement or retardation of the fuel injection timing. The Prestroke of the plunger 12 is the distance between the bottom dead center of the plunger 12 and a point at which the groove 20 reach the top edge of the inlet 22.The start timing of the fuel injection is adjusted by raising the plunger 12 to change the position of contact between the start point 30(a) of groove 20 and the inlet 22.
[0017] A method of working of the fuel injection pump according to one embodiment of the invention, in a retardation mode, the fuel is sucked into the plunger 12 through the inlet 22. The downward movement of the plunger 12 causes fuel to be sucked through the inlet 22 into the plunger 12. Due to the movement of the cam, the plunger shifts upwards .The fuel is compressed due to the upward movement of the plunger 12. The timing of the fuel injection is controlled by the operation of a control rack (not shown) to change the rotational position of the plunger 12 relative to the barrel 14. The rotational position of the plunger 12 is a relative position between the inlet 22 and the control helix 18. The groove 20 present on the plunger 12 comes into contact with the inlet 22. The starting point 30(a) of the groove 20 will be in contact with a lower edge of the inlet 22. The fuel flows into the groove 20 and due to the further movement of the plunger 12, the deep edge 30(b) of the groove 20 comes into contact with the inlet 22. Due to the rotation of the plunger 12 the contact portion between the inlet 22 and the control helix changes, due to which the pre stroke of the plunger 12 is increased, retarding the fuel injection timing. When the plunger 12 is rotated further, bringing the inlet 22 in communication with the groove 20 end point 30 (c),the retardation in the fuel injection timings is achieved at a full load condition 26(b). Due to the further moment of the plunger 12, the inlet 22 gets closed and the fuel in the plunger 12 gets compressed and is injected into an injector. At part loads 26(a) (for instance, 10% to 95% of load) fuel will be injected using starting point 30(a) of groove 20 compared to full load 26(b) (for instance, 100% load), so that injection will be delayed compared to full load 26(b).The slope of the groove 20 will decide the amount of retardation at part load 26(a) when compared to full load 26(b).
[0018] For instance, if a 9mm cam is used to move the plunger 12 in the barrel 14, the rotation of the cam shaft is converted into a reciprocating motion on a part of the plunger 12. Due to the rotation of the cam, the plunger 12 will have a 3mm upward shift. Due to the shift in the plunger 12, the inlet 22 is closed and the fuel in the plunger gets compressed and is injected into the injector. The plunger injects the fuel into the injector within 20 sec with the 3mm upward lift .The groove 20 present on the plunger head 21 of the plunger 12 will have a depth of 1mm. Due to the groove 20 of 1mm, the plunger 12 has to shift upwards up to 4mm, i.e. the cam has to rotate further to move the plunger 12 to have a 4mm shift. If the plunger takes 20 sec to inject the fuel into the injector with a 3mm shift, due to the groove and 4mm shift, the plunger takes 30 sec to inject the fuel into the injector. The retardation in the fuel injection timing is achieved.
[0019] A method of working of the fuel injection pump according to another embodiment of the invention, in the advanced mode, the deep edge 30(b) of the groove 20 will be away from the inlet 22. The fuel is sucked into the plunger 12 through the inlet 22. When the plunger 12 rotates, the starting point 30(a) of the groove 20 will comes into contact with the lower edge of the inlet 22 and the fuel is flows into the groove 20. When the load on the engine increases, the plunger rotates further bringing the groove 20 in contact with the inlet 22. When the engine experiences a full load (at 26(b)),a point on the surface of the groove 20, in line with the deep edge 30(b) of the groove 20 will be in contact with the upper edge of the inlet 22. Due to the further moment of the plunger, the inlet 22 gets closed and the fuel inside the plunger is compressed and is injected into the injector reducing the retardation timings.ie, advancing the fuel injection timing.
[0020] For instance, at initial load on the engine, the starting point 30(a) of the groove 20 comes into contact with the inlet 22. Due to the rotational movement of the plunger, the fuel is flows into the groove 20. At partial load 26(a), the groove will be in communication with the inlet 22 allowing the fuel to flow into the groove 20. When the engine experiences a full load 26(b), due to the changed configuration of the groove 20, the point on the surface of the groove 20 in line with the deep edge 30(b) of the groove 20 comes into contact with the inlet 22. With the further rotational movement of the plunger 12, the inlet is closed 22 and the fuel is compressed and injected with a reduction in the retardation time of the injection of the fuel, i.e. advancing the fuel injection at full load. The present invention can be applied to a wide range of engine requirements by appropriately varying the form, position, slope and relative positional arrangement of the groove and the control helix 9 and the other parts.
[0021] With the groove disclosed in this invention, additional flexibility in timing at higher loads is achieved. The position of the groove can be customized based on the application requirement and potential, to get the better fuel consumption and emissions.
[0022] It must be understood that the examples and embodiments of the components explained in the detailed description are only illustrative and do not limit the scope of the invention. The scope of this invention is only limited by the scope of the claims.