Claims:
We Claim:
1. A fuel supply system (10) in a vehicle , said system (10) comprising :
- a metering unit (12) connected to a high pressure pump (14);
- an electronic control unit (ECU) (16) connected to said metering unit (12), said ECU (16) adapted to control at least one operation of said metering unit (12);
- a back flow path (18) connected between said high pressure pump (14) and a fuel tank (24);
characterized in that:
- an additional flow path (20) is made in said system (10), connecting said metering unit (12) and said back flow path (18), such that, a part of fuel leaked from said metering unit (12) during a closed state is made to flow into said fuel tank (24) via said additional flow path (20).
2. The fuel supply system (10) as claimed in claim 1, wherein said additional flow path (20) is in fluid communication with said back flow path (18).
3. The fuel supply system (10) as claimed in claim 1, further comprises an electronically controlled valve (22) positioned in said additional flow path (20), adapted to allow said leaked fuel to flow into said back flow path (18).
4. The fuel supply system (10) as claimed in claim 3, wherein said valve (22) is a uni-directional valve.
5. The fuel supply system (10) as claimed in claim 3, wherein said ECU (16) adapted to open said valve (22) upon detecting a closed state of said metering unit (12).
6. The fuel supply system (10) as claimed in claim 1, wherein said additional flow path (20) is made at a bottom portion of said metering unit (12), such that, said leaked fuel is made to flow into said back flow path (18) via said additional flow path (20)
, Description:Complete Specification:
The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed.
Field of the invention
[0001] This invention relates to a fuel supply system in a vehicle.

Background of the invention
[0002] The conventional fuel delivery system [prior art description] is a fuel tank with a built-in fuel pump is provided for supplying fuel to a plurality of fuel injectors located in the fuel track. An electronic control unit (ECU) controls each fuel injector. The fuel pump is operated at a constant speed,
sometimes delivering 90-100 liters per hour. In idle state, the engine requires only about 3 liters per hour, so that case 87 -97 liters per hour is returned to the fuel tank through the return line from the pressure regulator. In connection with the return of the fuel into the relatively low pressure and a low temperature fuel tank from hot engine area there are a number of problems like evaporation of the fuel from the fuel tank and the like.
[0003] A Prior art document CN 202792458 discloses a high-Pressure Fuel supply pump comprising a compression chamber, a plunger reciprocating in the compression chamber for pressurizing fuel in the compression chamber. A discharge valve for discharging pressurized fuel from the compression chamber to a high-pressure fuel passage of a high-pressure fuel supply system for supplying high-pressure fuel to an internal combustion engine. A first solenoid actuated valve for connecting and disconnecting a first low-pressure fuel passage and the compression chamber. The high-pressure fuel supply pump further comprises a second solenoid actuated valve for connecting and disconnecting a second low-pressure fuel passage and the compression chamber.

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 supply system in a vehicle in accordance with one embodiment of the invention; and
[0006] Fig. 2 illustrates a fuel supply system in a vehicle in accordance with one embodiment of the invention.

Detailed description of the embodiments
[0007] Fig.1 illustrates a fuel supply system in a vehicle, in accordance with one embodiment of the invention. The fuel supply system 10 comprises a metering unit 12 connected to a high-pressure pump 14 and an electronic control unit (ECU) 16. The ECU 12 adapted to control at least one operation of the metering unit 12. The fuel supply system 10 further comprises a back flow path 18 connected between the high-pressure pump 14 and a fuel tank 24. The fuel supply system 10 further comprises an additional flow path 20 is made in the system 10, connecting the metering unit 12 and the back flow path 18, such that, fuel leaked from the metering unit 12 during a closed state is made to flow into the fuel tank 24 via the additional flow path 20.

[0007] Further the construction of the fuel supply system 10 and the components of the fuel supply system 10 and the working of the components are explained below. The fuel supply system 10 comprises the fuel tank 24 connected to the high-pressure fuel pump 14. The fuel pump 14 is connected to the common rail, which is further connected to the injector. A person skilled in the art knows the connections and the working of the above-disclosed components. The metering unit 12 can be positioned at the inlet of the high-pressure pump 14 or at the outlet based on the requirement. According to one embodiment of the invention, the metering unit 12 is positioned at the inlet of the high-pressure pump 14, such that, the operation of the metering unit 12 ensures the flow of a defined amount of fuel into the high-pressure pump 14.

[0008] The electronic control unit (ECU) 16 controls the metering unit 12. The ECU 16 controls the opening and closing of the metering unit 12 as per the engine requirement. According to one embodiment of the invention, the ECU 16 is an engine ECU. The additional flow path 20 is made at the bottom portion of the metering unit 12, connecting the back flow path 18, such that, the fuel that is leaked from the metering unit 12 is redirected back to the fuel tank 24. The size and shape of the additional flow path 20 can be varied based on the engine and the high-pressure pump capacities. However, the size is not restricted to the above disclosed, but can be of any size based on the requirement that is known to a person skilled in the art.

[0009] A method of working of the fuel supply system 10 is explained as follows. The fuel from the fuel tank 24 is pumped into the high-pressure pump 14 via the metering unit 12. The pressurized fuel from the high-pressure pump 14 is pumped into the common rail unit. The metering unit 12 is opened to allow the flow of the fuel into the high-pressure pump 14 from the fuel tank 24. During the downhill movement of vehicle or no demand of fuel by engine, ECU16 closes the metering unit 12. In closed state of metering unit 12, fuel leaks to the high pressure pump 14 because of clearances in metering unit 12. The leaked fuel is made to flow back to the fuel tank 24 via the additional flow path 20, which is in fluid communication with the back flow path 18. The amount of the fuel leaked from the metering unit 12, when the metering unit 12 is in closed condition is very small. During the open state of the metering unit 12, a negligible amount of fuel will escape from the additional flow path 20 back to the tank 24 due to the size of the additional flow path 20 that is made at the bottom portion of the metering unit 12.

[0010] Fig.2 illustrates a fuel supply system 10 in a vehicle in accordance with one embodiment of the invention. The fuel supply system 10 further comprises an electronically controlled valve 22 is positioned in the additional flow path 20. The valve 22 is in fluid communication with the metering unit 12 and the back flow path 18. The valve 22 is a uni-directional valve. The valve 22 is connected to the electronic control unit (ECU) 16 present in the fuel supply system 10. The ECU 16 is adapted to open or close the valve 22 based on the metering unit 12 operating condition. The ECU 16 opens the valve 22 upon closing the metering unit 12. The fuel leaked from the metering unit 12 is made to flow through the valve 22 that is present in the additional flow path 20.

[0011] A method of working of the fuel supply system 10 with the additional flow path 20 comprising the electronically controlled valve 22 is explained as follows. In the fuel flow cycle, the metering unit 12 positioned at an inlet of a high-pressure pump 14, ensures the defined amount of fuel to flow into the pump 14. When the ECU 16 adapted to open the metering unit 12, the defined amount of fuel flows into the pump 14 through the metering unit 12. When the ECU 16 adapted to close the metering unit 12, then a small amount of fuel is leaked from the metering unit 12. This leaked fuel will have a very low-pressure value, which is not sufficient to open the low-pressure value in the fuel supply system 10. Upon detecting the closed state of the metering unit 12, the ECU 16 opens the electronically controlled valve 22 for the flow of the leaked fuel from the metering unit 12. The fuel that is leaked from the metering unit 12, flows into the additional flow path 20 and then through the valve 22, flows into the back flow path 18 and thus into the tank 24. The size of the additional flow path 20 is made in such way that, the valve 22 can be positioned inside the additional flow path 20.

[0012] With the above-disclosed fuel supply system 10, the usage of zero delivery bore and the filler to provide passage to leaked fuel to backflow can be avoided. The machining of the assembly of the components of the system 10 will be simpler with the current additional flow path 20. Since, the zero delivery bore and the filler is avoided in the current design, the manufacturing cost, material cost and assembly cost can be reduced. Elimination of materials like zero delivery throttle and a ball-closing bore in turn reduces the corresponding material cost.

[0013] 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.