Claims:We Claim:
1. A high pressure fuel pump (10), said high pressure fuel pump (10) comprising a unidirectional flow control valve (11) integrated within said high pressure fuel pump (10), said unidirectional flow control valve 11 comprising:
a fuel inlet passage comprising a first chamber (12) and a second chamber (14) that is in flow communication with the first chamber (12); characterized in that
a plate (16) positioned within said second chamber (14) and flush against an interface between said first chamber (12) and said second chamber (14), said plate (16) prevents fuel flowing from said first chamber (12) to said second chamber (14) when a pressure of fuel acting on said plate (16) is below a threshold value; and
a spring member (18) positioned between said plate (16) and an end of said second chamber (14) of said high pressure fuel pump (10), said plate (16) adapted to be displaced against a resistive force of said spring member (18) when fuel of a pressure that is above the threshold value acts on said plate (16), to facilitate permitting fuel to flow from said first chamber (12) to said second chamber (14).

2. The high pressure fuel pump (10) in accordance with Claim 1 further comprising a pumping chamber (21) defined adjacent said second chamber (14), wherein fuel is permitted to flow from said second chamber (14) to said pumping chamber (21) of said high pressure fuel pump (10).

3. A unidirectional flow control valve (11) for a high pressure fuel pump (10), said unidirectional flow control valve (11) comprising a fuel inlet passage comprising a first chamber (12) and a second chamber (14), said unidirectional flow control valve (11) further comprising:
a plate (16) positioned within said second chamber (14) and flush against said first chamber (12), said plate (16) prevents fuel flowing from said first chamber (12) to said second chamber (14) when a pressure of fuel acting on said plate (16) is below a threshold value; and
a spring member (18) positioned between said plate (16) and an end of said second chamber (14) of said high pressure fuel pump (10), said plate (16) adapted to be displaced against a resistive force of said spring member (18) when fuel of a pressure that is above the threshold value acts on said plate (16) to facilitate permitting fuel to flow from said first chamber (12) to said second chamber (14).

4. The unidirectional flow control valve (11) in accordance with Claim 3 further comprising a pumping chamber (21) defined adjacent said first chamber (12), wherein fuel is permitted to flow from said first chamber (12) to said pumping chamber (21) of said high pressure fuel pump (10).

, Description:Field of the invention
[0001] This invention relates to a unidirectional flow control valve, and more particularly to a unidirectional flow control valve for a high pressure fuel pump.

Background of the invention
[0002] GB Patent Application Number 248957A describes a direct air pressure apparatus. A system for raising liquid fuel from a low-level tank for feeding a carburetor comprises a suction or pumping chamber connected by a pipe to a cylinder and piston for producing alternate pressure and suction, by a valve less pipe to the fuel tank, and by a conduit, check valve, chamber, and pipe to the carburetor, the resistance to backflow through the pipe being greater than the minimum resistance to outflow through the conduit. The fuel enters the chamber through a stand pipe having apertures surrounded by a cap and a filtering screen. When the carburetor has been filled, further action of the device causes an accumulation of air pressure in the chamber to balance the pressure impulses in the chamber 10, the fuel then surging idly in the pipes to and from the chamber. In a modification, the impulses are produced by a cam-actuated piston in a cylinder above the chambers the cylinder being closed by a head having a shank. The fuel inlet to the chamber is controlled by a ball valve carried by a float and the outlets to the chamber by a disc valve, the chamber being connected to the carburetor. The valve is initially in contact with the lower seat, so that it acts as a non-return inlet valve until sufficient fuel is drawn into the chamber to lift the float. When the fuel reaches normal level, the valve is lifted from its seat and the inlet conduit is uncontrolled, as in the first form described above. If the fuel level rises further, e.g. on an incline, the float brings the valve into engagement with an upper seat, closing the inlet until the fuel level returns to normal, and so preventing accumulation of fuel and access of fuel to the chamber. In order to alter the capacity of the chamber, the plug may have an axial cavity closed by an end cap and connected to the air space in the chamber by a small hole in the wall of the cavity.

Brief description of the accompanying drawing
[0003] Figure 1 illustrates a schematic diagram of a unidirectional flow control valve for a high pressure fuel pump in one embodiment of the invention.
Detailed description of the invention
[0004] A high pressure fuel pump 10 is described. The high pressure fuel pump 10 comprises a unidirectional flow control valve 11 integrated within said high pressure fuel pump 10, said unidirectional flow control valve 11 comprising a fuel inlet passage comprising a first chamber 12 and a second chamber 14 that is in flow communication with the first chamber 12. A plate 16 is positioned within the second chamber 14 and flush against an interface between the first chamber 12 and the second chamber 14, the plate 16 prevents fuel flowing from the first chamber 12 to the second chamber 14 when a pressure of fuel acting on the plate 16 is below a threshold value. A spring member 18 is positioned between the plate 16 and an end of the second chamber 14 of the high pressure fuel pump 10, the plate 16 adapted to be displaced against a resistive force of the spring member 18 when fuel of a pressure that is above the threshold value acts on the plate 16, to facilitate permitting fuel to flow from the first chamber 12 to the second chamber 14.
[0005] In addition, a unidirectional flow control valve 11 for a high pressure fuel pump 10 is described. The unidirectional flow control valve 11 comprises a fuel inlet passage comprising a first chamber 12 and a second chamber 14, the unidirectional flow control valve 11 further comprising a plate 16 positioned within the second chamber 14 and flush against the first chamber 12, the plate 16 prevents fuel flowing from the first chamber 12 to the second chamber 14 when a pressure of fuel acting on the plate 16 is below a threshold value. A spring member 18 is positioned between the plate 16 and an end of the second chamber 14 of the high pressure fuel pump 10, the plate 16 adapted to be displaced against a resistive force of the spring member 18 when fuel of a pressure that is above the threshold value acts on the plate 16 to facilitate permitting fuel to flow from the first chamber 12 to the second chamber 14.
[0006] Figure 1 illustrates a schematic diagram of a unidirectional flow control valve 11 for a high pressure fuel pump 10. The high pressure fuel pump 10 comprises a housing 13. The housing 13 comprises a fuel inlet passage that comprises a first chamber 12 and a second chamber 14 that is in flow communication with the first chamber 12. In an exemplary embodiment, a diameter of the second chamber 14 is larger than a diameter of the first chamber 12. A plate 16 is positioned within the second chamber 14, wherein the plate 16 is flush against an interface between the first chamber 12 and the second chamber 14. A spring member 18 is positioned between the plate 16 and an end of the second chamber 14 of the high pressure fuel pump 10. When a pressure of fuel acting on the plate 16 is below a threshold value, the plate 16 prevents fuel flowing from the first chamber 12 to the second chamber 14. More specifically, when the pressure of fuel acting on the plate 16 is below the threshold value, the resistive force of the spring member 18 prevents the plate 16 from being displaced in the direction of the spring member 18. Therefore, the fuel continues to remain within the first chamber 12. When fuel of a pressure that is above the threshold pressure acts on the plate 16, the plate 16 overcomes the resistive force of the spring member 18. This causes the plate 16 to displace against the resistive force of the spring member 18, thereby permitting the fuel from being channeled from the first chamber 12 to the second chamber 14.
[0007] A piston 20 is defined within the pumping chamber 21 of the high pressure fuel pump 10. The pumping chamber 21 of the high pressure fuel pump 10 is in flow communication with the second chamber 14 and receives fuel that is supplied from the second chamber 14. When the fuel flows from the first chamber 12 to the second chamber 14, the pressurized fuel flows into the pumping chamber 21 where it is further pressurized by the piston 20 and delivered out of the high pressure fuel pump 10.
[0008] A working of the unidirectional flow control valve 11 for the high pressure fuel pump 10 is described as an example. Fuel flows through the fuel inlet passage to the pumping chamber 21 of the high pressure fuel pump. More specifically, fuel is channeled through the first chamber 12 of the high pressure fuel pump 10. When the pressure of fuel acting on the plate 16 is below the threshold value, the resistive force of the spring member 18 prevents the plate 16 from being displaced in the direction of the spring member 18. Therefore, the fuel continues to remain within the first chamber 12. As the pressurized fuel continues to act on the plate 16, the plate 16 is displaced against a resistive force of the spring member 18. When the pressure of fuel acting on the plate 16 is above the threshold pressure, the plate 16 overcomes the resistive force of the spring member 18. The pressurized fuel acting on the plate 16 causes the plate 16 to displace in the direction of the spring member 18, thereby permitting the fuel to be channeled from the first chamber 12 to the second chamber 14. The pressurized fuel from the second chamber 14 is allowed to flow into the pumping chamber 21 of the high pressure fuel pump 10.
[0009] Since the plate 16 is of a rectangular cross section, there is surface contact between the plate 16 and the interface between the first chamber 12 and the second chamber 14. Therefore, even if the plate 16 gets eroded over a period of time, fuel from the pumping chamber 21 of the high pressure fuel pump 10 cannot flow back into the first chamber 12. This is because, sealing contact will still continue to be maintained between the plate 16 and the first chamber 12 of the high pressure fuel pump 10.
[0010] 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 scope of the claims.