Claims:We Claim:
1) A high Pressure Fuel Pump (100) for a fuel injection device of an internal combustion engine that comprises at least an inlet (101) for entry of a low pressure fuel (P1) coming from the fuel tank, a backflow (102) for outflow of fuel at pressure (P2) from the pump characterized in that said High Pressure Fuel Pump (100) comprises:

a channel (103) internally connecting the backflow (102) to the inlet (101);

a first non-return valve (V1 (104)) provided in the backflow (102) of said High Pressure Fuel Pump (100);

a second non-return valve (V2 (105)) provided in the channel (103) internally connecting the inlet (101) and the backflow (102).

2) The High Pressure Fuel Pump (100) as claimed in claim 1, wherein the first non-return valve (V1) (104) diverts the flow of a required quantity of fuel at pressure (P2) from the backflow (102) to the channel (103).

3) The High Pressure Fuel Pump (100) as claimed in claim 2 where the second non-return valve (V2) (105) restricts the flow of fuel at pressure (P1) from entering the channel (103).
, 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] The present invention relates to a high pressure fuel pump for a fuel injection device.
Background of the invention
[0002] Fuel pumps especially those used in Common Rail Fuel Injection Systems are usually High Pressure Fuel Pumps. These High Pressure Fuel Pumps draw fuel from the fuel tank and supply it to the Common Rail. The High Pressure Fuel Pumps compress the fuel drawn from the fuel tank to a high pressure required for injection. During the functioning of the high pressure fuel pump a portion of the fuel is used for lubrication of various components of the High Pressure Fuel Pump. After lubrication this fuel goes to a backflow circuit of the High Pressure Fuel Pump and subsequently back to the fuel tank. Only the fuel compressed to a high pressure is supplied to the Common Rail for injection.

[0003] Patent Application CN103541844A discloses a Fuel Injection Pump Backflow Connector. The fuel pump inlet and outlet port are joined by an "S" shaped connecter. This “S” shape connector has a filter which filters impurities in the backflow fuel. The filtering of impurities improves fuel cleanliness to prevent malfunction caused by impurities present in the fuel, thereby improving the reliability of the fuel pump.
Brief description of the accompanying drawings
[0004] Figure 1 depicts a high pressure fuel pumps with modified back-flow design in accordance with an embodiment of our invention.
Detailed description of the embodiments

[0005] Figure 1 depicts a High Pressure Fuel Pump (100) with modified back-flow design. Conventional High Pressure Fuel Pump (100) comprise an inlet (101) for entry of a low pressure fuel which is at Pressure (P1) coming from the fuel tank and a backflow (102) for outflow of fuel at a pressure (P2).In accordance with the present disclosure we propose the High Pressure Fuel Pump (100) characterized by a channel (103) internally connecting the backflow (102) to the inlet (101). A first non-return valve (V1 (104)) is provided at the backflow (102) of said High Pressure Fuel Pump (100). A second non return Valve (V2 (105)) is provided in the channel (103) internally connecting the inlet (101) and the backflow (102).

[0006] High Pressure Fuel Pumps compress fuel that enters the inlet (101) from the fuel tank at pressure (P1) to high pressures. This fuel is then delivered to a common rail which is a shared high-pressure reservoir for all injectors or directly to single fuel injector. However a portion of the fuel which enters the inlet (101) is used for lubrication of different parts of the High Pressure Fuel Pump (100), for example a drive train. This fuel which is used for lubrication is at pressure (P2) gets drained to the backflow (102) and subsequently to the fuel tank.

[0007] In the proposed invention we have created the channel (103) inside the High Pressure Fuel Pump (100) to allow the backflow fuel to go to the inlet (101) by the use of non-return valves ( V1(104) & V2(105)) provided in the channel (103) and the inlet (101). Non-return valves (V1 (104) & V2 (105)) allow fluids i.e. gas or liquid to flow in one direction only.

[0008] The first non-return valve (V1) (104) diverts the flow of a required quantity of fuel at pressure (P2) from the backflow (102) to the channel (103). This first non-return valve (V1 (104)) opens at a predefined pressure. This pressure is set in accordance with the design of the fuel pump to maintain an equilibrium between inlet (101) and backflow (102) pressure. For example the first non-return valve (V1) (104) will open at ~1bar. If the pressure in the backflow (102) is =1bar then the fuel will be routed back to the pump backflow (102) and subsequently to the tank. This is done to ensure that only a required quantity of fuel passes through the channel (103) to the pump inlet (101).

[0009] The second non-return valve (V2) (105) restricts the flow of fuel at pressure (P1) from entering the channel (103). The second non return valve (V2 (105)) present in the inlet (101) is set to an optimum pressure to allow the required quantity of fuel to pass through the pump inlet (101) and restrict the fuel coming from the fuel tank to be diverted to the channel (103).

[0010] The High Pressure Fuel Pump (100) in accordance with this disclosure will help in increasing the overall efficiency of vehicle. The High Pressure Fuel Pump (100) needs to draw a lesser quantity of fuel from the tank. The residual fuel left after lubrication of the different parts of the High Pressure Fuel Pump (100) is utilized effectively and increases the performance of the High Pressure Fuel Pump (100). This is in effect is a cost friendly solution to increase the mileage of a vehicle.

[0011] It must be understood that the embodiments explained in the above detailed description are only illustrative and do not limit the scope of this invention. Any modification in the embodiments with regard to High Pressure Fuel Pump (100) with modified back-flow design to increase their efficiency are envisaged and form a part of this invention. The scope of this invention is limited only by the claims