Claims:We Claim:

1. A high pressure fuel pump (12) for a fuel injection system (10), said high pressure fuel pump (12) comprising:
a pump housing (14), and a chamber room (16) positioned within said pump housing (14);
a fuel pumping chamber (18) coupled to said pump housing (14), and a suction valve (20) positioned within said fuel pumping chamber (18) to permit a flow of fuel into said fuel pumping chamber (18); characterized in that
a check valve (22) in flow communication between said chamber room (16) and an inlet of said suction valve (20), said check valve (22) adapted to permit a flow of pressurized fuel that is above a threshold pressure from said chamber room (16) to the inlet of said suction valve (20).

2. The high pressure fuel pump (12) for the fuel injection system (10) in accordance with Claim 1 wherein said check valve (22) is adapted to prevent a flow of fuel that is below the threshold pressure from said chamber room (16) to the inlet of said suction valve (20).

3. The high pressure fuel pump (12) for a fuel injection system (10) in accordance with Claim 1 wherein said check valve (22) is a spring loaded ball valve.

4. A check valve (22) for a high pressure fuel pump (12), said check valve (22) located between a chamber room (16) of said high pressure fuel pump (12) and an inlet of a suction valve (20), said suction valve (20) positioned within a fuel pumping chamber (18) of said high pressure fuel pump (12), said check valve (22) adapted to permit a flow of pressurized fuel that is above a threshold pressure from said chamber room (16) to the inlet of said suction valve (20). , Description:Field of the invention
[0001] This invention relates to a high pressure fuel pump for a fuel injection system, and more particularly to a check valve for controlling a mass flow rate of fuel to the high pressure fuel pump.

Background of the invention
[0002] EP 1279822 A2 describes a method for operating an internal combustion engine. The operating method has fuel fed from a metering device to a high pressure pump, supplying the fuel to a common-rail pressure reservoir for the fuel injection jets. The quantity of fuel provided by the metering device is limited by the maximum feed rate of the high pressure pump, the limitation over-ridden by a control device upon a reduction in the pressure in the common-rail pressure reservoir, with indication of a fault in front of the high pressure pump upon a subsequent pressure increase and a fault after the high pressure pump upon no pressure increase. Also included are independent claims for the following: (a) a computer program for a control device for an automobile IC engine; (b) a control device for an automobile IC engine; (c) an automobile IC engine.

Brief description of the accompanying drawing
[0003] Figure 1 illustrates a schematic diagram of a fuel injection system for an internal combustion engine.

Detailed description of the invention
[0004] A high pressure fuel pump 12 for a fuel injection system 10 is described. The high pressure fuel pump 12 comprises a pump housing 14, and a chamber room 16 positioned within the pump housing 14. A fuel pumping chamber 18 is coupled to the pump housing 14, and a suction valve 20 positioned within the fuel pumping chamber 18 to permit a flow of fuel into the fuel pumping chamber 18. A check valve 22 is in flow communication between the chamber room 16 and an inlet of the suction valve 20, the check valve 22 adapted to permit a flow of pressurized fuel that is above a threshold pressure from the chamber room 16 to the inlet of the suction valve 20.

[0005] Figure 1 illustrates a schematic diagram of a fuel injection system 10 for an internal combustion engine. The fuel injection system 10 comprises a high pressure fuel pump 12 that is used to supply pressurized fuel to a high pressure common rail. The high pressure fuel pump 12 comprises a pump housing 14. A chamber room 16 is defined within the pump housing 14 and contain mechanical components that require to be lubricated. A fuel pumping chamber 18 is coupled to the pump housing 14 and is adapted to deliver pressurized fuel from the high pressure fuel pump 12 to the high pressure common rail. A suction valve 20 is in flow communication with the fuel pumping chamber 18 and is used to draw fuel from a fuel source to the fuel pumping chamber 18 for pressurizing the fuel for delivery. A check valve 22 is in flow communication between the suction valve 20 and the chamber room 16 of the high pressure fuel pump 12. The check valve 22 permits a flow of fuel from the chamber room 16 to the suction valve 20 when the fuel in the chamber room 16 is above a threshold pressure as will be explained in more detail below.
[0006] A high pressure valve 24 is in flow communication downstream from the suction valve 20. When a pressure of fuel in the fuel pumping chamber 18 exceeds a critical threshold pressure, the pressurized fuel is supplied from the fuel pumping chamber 18 to the high pressure common rail via the high pressure valve 24. More specifically, when a pressure of fuel in the fuel pumping chamber 18 exceeds the critical threshold pressure, the pressurized fuel moves the ball of the high pressure valve 24 against a force of its spring member. Therein, the pressurized fuel is delivered from the pumping chamber 18 to the high pressure common rail via the high pressure valve 24.
[0007] An overflow valve 26 is in flow communication with the chamber room 16 of the high pressure fuel pump. The overflow valve 26 is adapted to channel pressurized fuel that is above a critical threshold pressure from the chamber room 16 to the pressure relief chamber 34. The pressurized fuel from the pressure relief chamber 34 is channeled back to the fuel tank 40 for recirculation.
[0008] A plurality of bearings 28 and 30 are in flow communication with the chamber room 16 of the high pressure fuel pump 12. When fuel is channeled into the chamber room 16 of the high pressure fuel pump 12 from the fuel tank 40, the pressurized fuel is channeled to the bearing 28 and the bearing 30 to lubricate the bearings 28 and 30 respectively. After the bearings 28 and 30 have been adequately lubricated, the excess fuel is channeled to the pressure relief chamber 34 and then channeled back to the fuel tank 40 for recirculation.
[0009] A low pressure feed pump 36 is in flow communication with fuel from a fuel tank 40. An engine control unit 38 is in electronic communication with the low pressure feed pump 36 and controls a mass flow rate of fuel from the low pressure feed pump 36. A fuel filter 32 is in flow communication with the low pressure feed pump 36 and filters the fuel that flows out of the low pressure feed pump 36. The fuel from the fuel filter 32 is allowed to flow into the chamber room 16 of the high pressure fuel pump 12 from where it is channeled to the check valve 22.
[0010] A working of the fuel injection system 10 for the internal combustion engine is described as an example. The engine control unit 38 controls a mass flow rate of fuel from the low pressure feed pump 36 to the fuel filter 32. The mass flow rate of fuel that flows from the low pressure feed pump 36 to the fuel filter 32 is dependent on the mass flow rate of fuel that is required to be pressurized and delivered from the high pressure fuel pump 12 to the high pressure common rail. The pressurized fuel that flows from the fuel filter 32 to the high pressure fuel pump 12 is used to lubricate the bearing 28, the bearing 30, as well as the other internal components of the high pressure fuel pump 12. As the low pressure feed pump 36 continues to deliver pressurized fuel to the high pressure fuel pump 12, the pressure of fuel in the high pressure fuel pump 12 increases. As the pressure of fuel in the high pressure fuel pump 12 increases above a threshold pressure, the check valve 22 is opened against the force of its spring member. Therein, pressurized fuel is delivered from the chamber room 16 of the high pressure fuel pump 12 to the pumping chamber 18 of the high pressure fuel pump 12 via the check valve 22 and the suction valve 20. When it is required to increase a quantity of fuel in the high pressure fuel pump 12, the engine control unit 38 controls the low pressure feed pump 36 such that a greater quantity of fuel is delivered from the low pressure feed pump 36 to the high pressure fuel pump 12 via the fuel filter 32. Therein, a greater quantity of fuel is delivered from the chamber room 16 to the suction valve 20 via the check valve 22.
[0011] It must be understood that the embodiments explained above are only illustrative and do not limit the scope of the disclosure. Many modifications in the embodiments with regard to leverage and dimensions of various components are envisaged and form a part of this invention. The scope of the invention is only limited by the claims.