CLIAMS:I Claim:
1. A double acting pump (10) in a common rail system, said double acting pump comprising :
a first chamber (12) located at one end of said pump (10);
a second chamber (22) located at other end of said pump (10);
a plunger (32), at least a part of said plunger (32) reciprocating in said first chamber (12) and said second chamber (22);
a drive rod (34) connected between said plunger (32) and one end of a piston (36) and other end of said piston (36) is connected to a drive source (38);
said first chamber (12) comprises a first inlet (14), a first outlet (16) and a valve (18) in flow communication with said first inlet (14) and said first outlet (16);
said second chamber (22) comprises a second inlet (24), a second outlet (26) and a valve (28) in flow communication with said second inlet (24) and said second outlet (26);
displacement of said piston (36) causes displacement of said driver rod (34) and plunger (32) in a manner such that displacement of plunger (32) in either direction pressurizes fuel in one of said two chambers (12,22) and enables fuel to flow out one of said two chambers (12,22).

2. The double acting pump (10) claimed in claim (1), wherein said valve (18) of said first chamber (12) and said valve (28) of said second chambers (12) allows said fuel to flow into one of said two chambers (12, 22) and allows delivering of said pressurized fuel into said common rail.

3. The double acting pump (10) claimed in claim (1), wherein said valve (18) of said first chamber (12) comprises an inlet valve (19 (a)) and a delivery valve (30 (a)) and said valve (28) of said second chamber (28) comprises an inlet valve (19 (b)) and a delivery valve (30 (b)).

4. The double acting pump (10) claimed in claim (1), wherein said plunger (32) displacement will be in same direction as displacement of said piston (36). ,TagSPECI:The following specification particularly describes the invention and the manner in which it is to be performed.

Field of the invention
[001] This invention relates to a double acting pump in a common rail system.

Background of the invention
[002] Double acting reciprocating piston pumps are an efficient means for flowing liquids because the pump both delivers and aspirates the liquid to be pumped with each stroke of the piston. It fills the liquid at one end of the pump, and discharges pressurized liquid from the other end. On the return stroke, the end of pump which is just emptied is filled, and the end just filled is emptied. With a double acting pump, the output pulsation can be reduced.

[003] A published German patent application 102013205807discloses a machine having a motor driven reversible hydraulic pump, arranged in a closed circuit. The pump directly acts on a double-acting cylinder with a piston surface and a double-sided piston rod. A rudder is connected to a hydraulic cylinder arrangement through a connecting rod. The connecting rod maintains a constant predetermined pressure in the hydraulic circuit.

Brief description of the accompanying drawings
[004] Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:
[005] Figure 1 illustrates a double acting pump in a common rail system according to one embodiment of the invention; and
[006] Figure 2 illustrates a double acting pump in a common rail system according to one embodiment of the invention.

Detailed description of the invention
[007] Figure 1 illustrates a double acting pump 10 in a common rail system (not shown) according to one embodiment of the invention. The double acting pump 10 comprises a first chamber 12 located at one end of the pump 10 and a second chamber 22 located at other end of the pump 10. The double acting pump 10 comprises a plunger 32, at least a part of the plunger 32 reciprocating in the first chamber 12 and the second chamber 22. The double acting pump 10 also comprises a drive rod 34 connected between the plunger 32 and one end of a piston 36 and other end of the piston 36 is connected to a drive source 38. The first chamber 12 comprises a first inlet 14, a first outlet 16 and a valve 18 in flow communication with the first inlet 12 and the first outlet 14. The second chamber 22 comprises a second inlet 24, a second outlet 26 and a valve 28 in flow communication with the second inlet 24 and the second outlet 26. The displacement of the piston 36 causes displacement of the drive rod 34 and plunger 32 in a manner such that displacement of plunger 32 in either direction pressurizes fuel in one of the two chambers (12,22) and enables fuel to flow in one of the two chambers (12,22).

[008] A rotary motion of an engine is converted into a reciprocating motion of the drive source 38. One end of the piston 36 is connected to the drive source 38 and the other end of the piston 36 is coupled to a drive rod 34.The drive source 38 can be chosen from a group of drive sources like a crankshaft or a flywheel or the like. Due to the reciprocating motion of the drive source 38, the piston 36 moves which in turn moves the drive rod 34 and the plunger 32. The movement of the drive rod 34 and the plunger 32 will be in same direction as the movement of the piston 36.

[009] The low pressure fuel fills into the first chamber 12 through the first inlet 14. Due to the rotation of the drive source 38 (i.e., say from 0 degree to 180 degrees), the piston 36 moves backwards (as indicated by the arrow in figures 1 and 2) which moves the drive rod 34 and the plunger 32 into the first chamber 12. The fuel in the first chamber 12 is pressurized by the movement of the plunger 32. The pressurized fuel flows through the valve 18 into the common rail. Simultaneously, as the plunger 32 moves towards the first chamber 12, the plunger 32 in the second chamber (22) moves such that the fuel is allowed to fill in the second chamber 22. The flowing of the fuel into the second chamber 22 and the discharging of the pressurized fuel from the first chamber 12 through the valve 18 happens simultaneously. When the drive source 38 rotates further (i.e. say from 180 degrees to 360 degrees), the piston 36 moves forward making the drive rod 34 and the plunger 32 to move forwards towards the second chamber 22. The forward movement of the plunger 32 pressurizes the fuel in the second chamber 22. The pressurized fuel is discharged via the valve 28 of the second chamber 22 into the common rail. The valves (18, 28) located in both the chambers (12, 22) respectively allows the fuel to fill into one of the chambers (12, 22) and simultaneously delivers the pressurized fuel into the common rail through one of the chambers (12, 22). The valve (18, 28) comprises an inlet valve (19) and a delivery valve (30) in each chamber. The first and second inlet (14, 24 and the first and the second outlet (16, 26) are in flow communication with the valves (18, 28) of the respective chambers (12, 22). At the other end of the pump 10, the fuel will be flown into in the first chamber 12 and the pressurization of the fuel takes place due to the rotation of the drive source 38 (i.e., from 0 to 180 degrees).

[0010] During the fuel pressurization in the first chamber 12, at least some portion/amount of the low pressure fuel coming from the fuel tank (not shown) passes through the first outlet 16 and returns back to the fuel tank. Similarly, during the fuel pressurization in second chamber 22, the low pressure fuel coming from the fuel tank passes through the second outlet 26 and returns back to the fuel tank. A fuel leaking between plunger (?) and a housing 20 is collected in a collector 44 and lead back into the fuel tank.

[0011] Figure 2 illustrates a double acting pump 10 in a common rail system (not shown) according to one embodiment of the invention. The double acting pump 10 comprises a pivot 42 on the drive rod 34. When the drive source 38 rotates, the piston 36 moves either forwards or backwards. Due to the displacement of the piston 36, the drive rod 34 also displaces from the initial position displacing the plunger 32 (since, the drive rod 34 is coupled to one end of the piston 36). The displacement of the drive rod 34 and the plunger 36 will be in opposite direction to the displacement of the piston 36. The displacement of the plunger 32 in either direction pressurizes fuel in one of the two chambers (12, 22) and enables fuel to flow in one of the two chambers (12, 22). With an optimized linkage ratio, the plunger 32 displacement can be sufficiently increased compared to piston 36 displacements, thus getting a higher velocity required to generate the higher pressures.

[0012] With the double acting pump 10 and the method of working of the double acting pump 10 disclosed above; the output pulsation can be reduced compared with a single acting pump. With the above method, components like a roller tappet, a camshaft, a bearing, a plunger return spring and a separate lubrication circuit used in the current oil lubricated pumps can be eliminated. Elimination of the plunger return spring will reduce the drive torque of the pump.

[0013] It must be understood that the embodiments explained in the above detailed description is only illustrative and does not limit the scope of this invention. The scope of this invention is limited only by the scope of the claims. Many modification and changes in the embodiments aforementioned are envisaged and are within the scope of this invention.