CLIAMS:We claim:
1. A fuel pump 1000, said fuel pump comprising:
a motor 101;
a disc 102 mounted on the motor 101;
a pin 103 located on the disc 102 connected to a control rod 104;
said disc 102 adapted to move said control rod 104 against a force of a spring piston 105; and
said control rod 104 adapted to rotate at least one fuel discharge valve 106 of said fuel pump 1000 to drain excess fuel from the fuel pump 1000 based on a current value supplied to the motor 101.

2. The fuel pump 1000 as claimed in claim 1, wherein the fuel pump 1000 is an in-line pump.

3. The fuel pump 1000 as claimed in claim 1, wherein the current value is dependent on an engine speed.

4. The fuel pump 1000 as claimed in claim 1, wherein the motor 101 is a servo motor.

5. A control unit for the fuel pump 1000, said control unit adapted to,
receive an engine speed of a vehicle from an engine speed sensor;
provide a current to be supplied to a motor 101 to rotate a disc 102 in dependence of said engine speed;
said disc 102 adapted to move a control rod 104 against a force of a spring piston 105; and
said control rod 104 adapted to rotate at least one fuel discharge valve 106 of the fuel pump 1000 to drain excess fuel from the fuel pump 1000 based on the current supplied to the motor 101.

6. The control unit for the fuel pump 1000 as claimed in claim 5, wherein said control unit stores a plurality of current values associated with a plurality of engine speed values, said control unit adapted to supply at least one of said plurality of current values to said motor 101 in dependence of said at least one engine speed value. ,TagSPECI:The following specification particularly describes the invention and the manner in which it is to be performed.

Field of the invention
[001] This disclosure relates to a fuel pump.

Background of the invention:
[002] A fuel pump for an internal combustion engine is provided to draw fuel from a fuel tank and supply the fuel to the internal combustion engine of a vehicle. The fuel consumption of the vehicle is relatively high at low speeds. Since the fuel supplied to an engine is a uniformly decreasing curve with respect to an engine speed for a vehicle, an excess amount of fuel is supplied to the internal combustion engine at low speeds. A control unit for the fuel pump is used to control the amount of fuel supplied to the internal combustion engine. The control unit for the fuel pumps controls with respect to operating speed of the fuel pump to control the fuel pressure in a fuel supply system. In certain cases, excess fuel is drained to regulate the fuel supplied to the internal combustion engine. Excess fuel is drained because the quantity supplied at lower engine speed is much higher than the desired quantity due to the fuel pump’s natural hydraulics. One of the known techniques uses pressure relief valves in the high pressure common rail of a common rail system to drain the excess fuel from being supplied to the internal combustion engine. A simplified and an easy approach for draining excess fuel from being supplied to the internal combustion engine is required to supply sufficient quantity of fuel at low speeds.

[003] The US patent document numbered US 4539809, describes a system for venting excess fuel from the fuel pump of a jet engine. The system comprises a drain line connected at a first end to the vent valve of the fuel pump and at a second end to the main fuel supply line for the engine, for draining the excess fuel from the pump to the main fuel line, a check valve in the drain line near the second end thereof for restricting fuel flow through the drain line in a direction from the first end to the second end, and a vent line having a restriction therein defining an orifice of predetermined size connecting the drain line to an overboard dump port open to ambient.

Brief description of the accompanying drawings:
[004] An embodiment of the disclosure is described with reference to the following accompanying drawings;
[005] Figure 1 illustrates a schematic diagram of a fuel pump in accordance with this invention;
[006] Figure 2 illustrates a schematic diagram of an fuel discharge valve of the fuel pump in accordance with this invention; and
[007] Figure 3 illustrates a schematic diagram of a spring piston of the fuel pump in accordance with this invention.

Detailed description of the embodiments:
[008] Figure 1 illustrates a schematic diagram of a fuel pump 1000 in accordance with this invention. The fuel pump 1000 comprises a motor 101; a disc 102 mounted on the motor; a pin 103 located on the disc 102 connected to a control rod 104; the disc 102 adapted to move the control rod 104 against a force of a spring piston 105; and the control rod 104 adapted to rotate at least one fuel discharge valve 106 of the fuel pump 1000 to drain excess fuel from the fuel pump 1000 based on a current value supplied to the motor 101.

[009] The schematic diagram as shown in figure 1 can be explained as follows. The fuel pump 1000 is an in-line pump. The motor 101 is a servo motor. The disc 102 mounted on the motor 101 is a servo disc. The motor 101 is in connection with the fuel pump 1000. The fuel supplied to an engine is a uniformly decreasing curve with respect to an engine speed for a vehicle. At lower engine speeds, the fuel supplied to the engine is greater than a required amount of fuel for a given engine speed. This result in an excess fuel supplied to the engine at lower engine speeds generating excess black smoke from the vehicle.

[0010] A control unit for the fuel pump 1000 provides a current value to be supplied to the motor 101 in dependence of an engine speed. The control unit for the fuel pump 1000 receives the engine speed of a vehicle from an engine speed sensor. The current value is supplied to the motor 101 of the fuel pump 1000. The motor 101 in turn rotates the disc 102 mounted on the motor 101 using the current value supplied to the motor 101. The pin 103 located on the disc 102 is connected to the control rod 104 and is as shown in Figure 2. The rotation of the disc 102 causes a linear movement of the connected control rod 104. This causes the control rod 104 to move against a force of the spring piston 105 as illustrated in the Figure 3. At least one spring 105a of the spring piston 105 controls the linear movement of the control rod 104. A linear movement of the control rod 104 either pushes or pulls at least one fuel discharge valve 106 of the fuel pump 1000. The at least one fuel discharge valve 106 are positioned in between a fuel drain pipe 107 on one side and a high pressure pipe 108 on the other side as shown in Figure 1. The fuel discharge valve 106 is, for example, a spherical butterfly valve. The linear movement of the control rod 104 rotates at least one fuel discharge valve 106 of the fuel pump 1000 to drain excess fuel from the fuel pump 1000 based on the current value supplied to the motor 101. As soon as the at least one fuel discharge valve 106 are opened, excess fuel flows back to the fuel tank through a fuel drain pipe 107. The excess fuel drained is again sent to a filter to reduce the work done by a feed pump or inlet of the fuel pump 1000.

[0011] The control unit for the fuel pump 1000 is adapted to provide a current to be supplied to the motor 101 to rotate the disc 102 in dependence of the engine speed. The control unit stores a plurality of current values associated with a plurality of engine speed values. The control unit is adapted to supply at least one of the plurality of current values to the motor 101 in dependence of the at least one engine speed value. The current value is a value of current required for the fuel pump 1000 to drain an excess fuel from the fuel pump 1000 at a given engine speed. At lower engine speeds, since excess fuel quantity is supplied to the engine of a vehicle, it is essential to supply a required amount of fuel to maintain the given engine speed. Thus, the current value is the value of current required for the fuel pump 1000 to supply the required amount of fuel to maintain the given engine speed. The excess fuel to be drained at the given engine speed is pre-determined based on pre-conducted vehicle tests. The control unit also comprises a value of the excess fuel and a required amount of fuel for each value of the engine speed along with the current value associated with the engine speed.

[0012] In an embodiment, the current value is dependent on a demand given to the fuel pump 1000. The current value to be supplied to the fuel pump 1000 for a demand given to the fuel pump 1000 is pre-determined and stored in the control unit. The control unit comprises a list of demand given to the fuel pump and a current value for each value of the demand given to the fuel pump.

[0013] For an engine speed below a threshold, the current value is greater than zero. Since the amount of fuel supplied for the engine speed below the threshold is greater than a required amount of fuel supplied to the engine, the current value supplied to the motor 101 to rotate the disc 102 is greater than zero. The fuel pump 1000 drains excess fuel to the fuel tank through the fuel drain pipe 107 thereby supplying only the required amount of fuel to the engine at lower engine speeds. Hence, for engine speeds below the threshold, the excess fuel is drained to the fuel tank preventing generation of black smoke at lower engine speeds. With the supply of only required amount of fuel to the engine, the generation of excess smoke is prevented and a better fuel economy is achieved at a given engine speed. pump 1000 allows better control on the fueling quantity. The fuel pump 1000 reduces the smoke values at lower engine speeds. The fuel pump 1000 helps to achieve a better fuel economy in city conditions where vehicles are run at lower engine speeds.

[0014] For an engine speed equal to or greater than the threshold, the current value is equal to zero. At higher speeds above the predefined threshold, since excess fuel is not supplied to the engine due to the natural hydraulics of the fuel pump 1000, the current value is equal to zero. Thus, the current value is a current value sufficient to supply the required fuel to the engine at a given engine speed.

[0015] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. 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.