CLIAMS:We claim:
1. A valve arrangement (10) for a fuel pump (12) comprising a pump body (14), said pump body (14) defining a pumping chamber (16) within, said valve arrangement (10) comprising:
- an inlet valve body (18) located in fluid communication with said pumping chamber (16);
characterized in that said valve arrangement (10) comprising:
- said inlet valve body (18) comprising at least two fuel flow paths (20,22) in fluid communication with each other, a first fuel path (20) allows fuel to flow from a fuel source to said fuel pump (12) and a second fuel flow path (22) allows fuel to flow from said first fuel path (20) to said pumping chamber (16)
- a valve pin (24) located in said second fuel flow path (22), said valve pin (24) adapted to be displaced along the length of the second fuel flow path (22) in dependence of the flow of fuel;
- a magnet (26) located at one end of said valve pin (24) and placed in said second fuel flow path (22); and
- a stopper element (28) located at the interface of said inlet vale body (18) and said pump body (14).
2. The valve arrangement (10) as claimed in claim 1, wherein said valve pin (24) located in said second fuel flow path (22) in a manner such that at least a part of the valve pin (24) extends from the second fuel flow path (22) into the pumping chamber (16).

3. The valve arrangement (10) as claimed in claim 1, wherein said stopper element (28) is located at the interface of said inlet valve body (18) and said pump body (14) in a manner such that at least a part of said stopper element (28) extends into the pumping chamber (16).
4. The valve arrangement (10) as claimed in claim 2 or 3, wherein movement of said at least a part of the valve pin (24) extending into said pumping chamber (16) is restricted by said stopper element (28).
5. The valve arrangement (10) as claimed in claim 1, wherein said magnet (26) is placed in a non-magnetic interface (30) in a manner such that said magnet (26) and said valve pin (24) are not in direct contact with each other.
6. The valve arrangement (10) as claimed in claim 1, wherein said magnet (26) placed in said non-magnetic interface (30) is located at one end of said second fuel flow path (22) away from said pumping chamber (16).
7. The valve arrangement (10) as claimed in claim 1, wherein said valve pin (24) comprises a slot (34) at the end of said valve pin (24) in proximity of said magnet (26). ,TagSPECI:Field of the invention:
[0001] This disclosure relates to a valve arrangement for a fuel pump.
Background of the invention:
[0002] A fuel injection system has a fuel tank where fuel is stored. A feed pump is used to supply fuel from the fuel tank to a high pressure fuel pump. While supplying the fuel from the feed pump to the high pressure fuel pump the fuel flows through a fuel filter. Before entering the high pressure pump a metering unit is provided to meter the quantity of fuel that is sent to the high pressure pump for pressurizing. The basic working principle of the metering unit is that it allows the fuel to enter the high pressure fuel pump only if the pressure of the fuel is greater than a valve that is indicated by the force required to move the components of the metering unit. The fuel enter the high pressure pump through an inlet valve provided in the high pressure fuel pump. The inlet valve known in the state of the art are usually a spring loaded valve. The working of the spring loaded valve is such that the valve pin of the inlet valve is biased against a spring. When the pressure of the fuel is greater than the force required to overcome the spring force, the valve pin is displaced from it position and the fuel enters the pumping chamber of the fuel pump.
[0003] Published US patent document US2003/0037822 discloses a check valve for a fuel pump of a vehicle includes a retainer adapted to be disposed in an outlet member of the fuel pump. The check valve also includes a valve seat adapted to be disposed in the outlet member and spaced from the retainer. The check valve includes a valve member disposed in the outlet member between the retainer and the valve seat. The valve member has a closed position to engage the valve seat to prevent fuel from flowing through the outlet member and an open position to allow fuel to flow through the outlet member. The check valve further includes a magnet cooperating with the valve member for generating a magnetic force on the valve member to maintain a contact force between the valve member and the valve seat when the valve member is in the closed position.
Brief description of the accompanying drawings:
[0004] An embodiment of the disclosure is described with reference to the following accompanying drawings;
[0005] Figure 1 illustrates the valve arrangement for a fuel pump in accordance with this disclosure; and
[0006] Figure 2 illustrates the valve pin of the valve arrangement in accordance with this disclosure.
Detailed description of the embodiments:
[0007] Figure 1 illustrates the valve arrangement 10 for a fuel pump in accordance with this disclosure. The fuel pump 12 comprises a pump body 14. The pump body 14 defines a pumping chamber 16 within the pump body. The valve arrangement 10 comprises an inlet valve body 18 located in fluid communication with the pumping chamber 16. The valve arrangement is characterized in a manner such that the valve arrangement 10 comprises: the inlet valve body 18 comprising at least two fuel flow paths 20, 22 in fluid communication with each other. A first fuel path 20 allows fuel to flow from a fuel source to said fuel pump 12 and a second fuel flow path 22 allows fuel to flow from the first fuel path 20 to the pumping chamber 16. A valve pin 24 is located in the second fuel flow path 22. The valve pin 24 is adapted to be displaced along the length of the second fuel flow path 22 in dependence of the flow of fuel. A magnet 26 is located on the valve pin 24 with the non-magnetic interface in between and placed at one end of the second fuel flow path 22, that end of the second fuel flow path being away from the pumping chamber 16 and a stopper element 28 is located at the interface of the inlet vale body 18 and the pump body 14.
[0008] Further details about the construction of the valve arrangement and the components of the valve arrangement will be explained in the following description. During the assembly of the fuel pump 12, a plunger is located in the bore provided in the pump body 14. One end of the bore has a diameter which is greater than the bore and forms the pumping chamber 16 of the pump body 14. The stopper element 28 is placed on the pump body 14 in proximity of the pump chamber 16. As seen is figure 1, a part of the stopper element 28 extends into the pumping chamber 16. The stopper element 28 also at least two holes 32. The holes 32 helps in flow of fuel that flows down the second fuel flow path 24 towards the pumping chamber 16 through the stopper element 28. The magnet 26 is first placed in a non-magnetic interface 30 such that the magnet 26 and the valve pin 24 are not in direct contact with each other. The magnet 26 with the non-magnetic interface is then fitted at the end of the valve pin 24 of the inlet valve body 18 which is away from the pumping chamber 16. The valve pin 24 is then inserted into the second fuel flow path 22. The valve pin 24 is made from metallic material. As seen in the figure 1, the operative lower portion of valve pin 24 has a diameter which is greater than the diameter of that portion of the valve pin 24 which is inserted in the second fuel flow path 22. Due to the difference in diameter the edge of the second fuel flow path 22 which is in proximity of the pumping chamber 16, acts as the valve seat for the valve pin 24. The inlet valve body 18 is then located on the pump body 14. Thus the stopper element 28 is located at the interface of the inlet valve body 18 and the pump body 14 in a manner such that at least a part of the stopper element 28 extends into the pumping chamber 16. When the inlet valve body 18 is located on the pump body 14 the valve pin 24 is located in the second fuel flow path 22 in manner such that at least a part of the valve pin 24 extends from the second fuel flow path 22 into the pumping chamber 16. As seen in figure 2, the valve pin 24 has a slot 34. The function of the slot 34 will be explained in the following paragraphs related to the working of the fuel pump.
[0009] The working of the fuel pump and the various components of the valve arrangement 10 can be explained as follows. A fuel injection system comprises a fuel tank, a feed pump and a fuel pump in accordance with this disclosure. The fuel from a fuel source such as a feed pump enters the fuel pump 12 through the inlet valve arrangement. The fuel enter the fuel pump 12 through the first fuel flow path 20. As the first fuel flow path 20 and the second fuel flow path 22 are in fluid communication with each other, the fuel flow from the first fuel flow path 20 to the second fuel flow path 22. As the fuel enters the second fuel flow path 22, the fuel enters the space along the part of the valve pin 24 which is located in the second fuel flow path 22. However, the valve pin 24 does not move along the length of the second fuel flow path 22. The valve pin along with the magnet 26 is attracted towards the blind end of the second fuel flow path 22.
[00010] Due to the attraction of the magnet 26 the valve pin 24 is pressed along the valve seat and fuel from the second fuel flow path 22 does not flow towards the pumping chamber 16. As the amount of the fuel flowing into the second fuel flow path 22 increases the pressure of the fuel that is exerted on the valve pin 24 increases. As soon as the pressure on the valve pin 24 is able to overcome the force of the magnet 26, the valve pin 24 is displaced along the length of the second fuel flow path 22. As soon as the valve pin 24 is displaced the fuel that is present in the second fuel flow path 22 flows into the stopper element 28 and through the holes in the stopper element 28 into the pumping chamber 16 of the fuel pump 12. However, the movement of the valve pin 24 which extends into the pumping chamber 16 is restricted by the stopper element 28. The restricted movement of the valve pin 24 ensures that the valve pin 24 does not fall into the pumping chamber 16. The restricted movement of the valve pin 24 is also such that the valve pin 24 is still within the magnet attraction zone of the magnet 26. Thus when the pressure of fuel being exerted on the valve pin 24 reduces, the magnet 26 attracts the valve pin 24 and stops the flow of fuel from the second fuel flow path 22 to the pumping chamber 16.
[00011] As mentioned earlier the magnet 26 is first located in a non-metallic interface 30 before being located on the valve pin 24 or in the second fuel flow path 22. The reason for locating the magnet in a non-metallic interface 30 is that, the non-metallic interface 30 prevents the permanent magnetization of the valve pin 24. Also, the slot 34 provided on the valve pin 24 is provided so that there is no formation of vacuum within the second fuel flow path 22 above the magnet 26, as formation of vacuum will not allow for the movement of the valve pin 24. Due to existence of vacuum if the valve pin 24 stops functioning then this would lead to failure of the fuel pump.
[00012] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this disclosure in terms of the metallic material used for manufacturing the valve pin, the dimensions of the valve pin, dimensions of the fuel flow paths, material of the stopper element and dimensions of the stopper element. 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.