CLIAMS:We Claim:

1. An overflow valve (10) for a fuel metering unit, said overflow valve (10) comprising:
an overflow valve body (12);
a spring element (14) positioned within said overflow valve body (12);
a screw plug (16) positioned against a first end (18) of said spring element (14);
a ball (20) positioned against a second end (22) of said spring element (14); characterized in that
said ball (20) containing at least one cavity (24) to facilitate minimizing swirl that occurs within said overflow valve body (12).
2. The overflow valve (10) in accordance with Claim 1 wherein said at least one cavity (24) is asymmetrically positioned with respect to an axis of said ball (20).
3. The overflow valve (10) in accordance with Claim 1 wherein said at least one cavity (24) is symmetrically positioned with respect to an axis of said ball (20).
4. The overflow valve (10) in accordance with Claim 1 wherein said at least one cavity (24) is one of a circular shaped cavity, a square shaped cavity, a triangular shaped cavity, and the like.
5. A fuel metering unit, said fuel metering unit comprising:
a housing and an overflow valve body (12) integrated within said housing;
a spring element (14) positioned within said overflow valve body (12), and a screw plug (16) positioned against a first end (18) of said spring element (14) to facilitate sealing said fuel metering unit;
a ball (20) positioned against a second end (22) of said spring element (14) and positioned within said fuel metering unit; characterized in that
said ball (20) containing at least one cavity (24) to facilitate minimizing swirl that occurs within said overflow valve body (12).
6. The fuel metering unit in accordance with Claim 5 wherein said at least one cavity (24) is asymmetrically positioned with respect to an axis of said ball (20).
7. The fuel metering unit in accordance with Claim 5 wherein said at least one cavity (24) is symmetrically positioned with respect to an axis of said ball (20).
8. The fuel metering unit in accordance with Claim 5 wherein said at least one cavity (24) is one of a circular shaped cavity, a square shaped cavity, a triangular shaped cavity, and the like. ,TagSPECI:Field of the invention
[0001] This invention relates to an overflow valve in a fuel metering unit.
Background of the invention
[0002] An overflow valve is used in a conventional fuel metering unit. A ball is inserted within an overflow valve body and is biased against a spring member. The ball facilitates sealing the overflow valve body at low fuel flow rates. When the flow rate of fuel increases, the ball is displaced against a force of the spring member. Therein, fuel enters the overflow valve body and is channeled to a fuel tank via a return flow path. At higher fuel flow rates however, a swirl occurs above the ball, at a side opposite that of a fuel inlet and within the overflow valve body. The swirling action caused by fuel flowing around the ball creates a high degree of noise within the overflow valve body. It is desired to reduce the degree of noise produced within the overflow valve body. This objective is accomplished by modifying an outer surface area of the ball that is inserted within the overflow valve body.
[0003] Indian Patent Application Number 6026/CHE/2014 describes a fuel metering unit 10. The fuel metering unit 10 comprises an overflow valve body integrated within a housing 12 of the fuel metering unit 10. A ball 26 is disposed within the overflow valve body and is in contact with a spring member 24 of the overflow valve body. The ball 26 facilitates closing an overflow passage 28 while the flow metering unit 10 is non-operational. The spring member 24 is located in the overflow valve body of the fuel metering unit 10 in a manner such that one end of the spring member 24 abuts a plug 22 while the opposite end of the spring member 24 is in contact with the ball 26.
Brief description of the accompanying drawings
[0004] Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:

[0005] Figure 1 illustrates an overflow valve in a fuel metering unit in one embodiment of the invention; and
Detailed description of the embodiments
[0006] Figure 1 illustrates an overflow valve 10 for a fuel metering unit. The overflow valve 10 comprises an overflow valve body 12 and a spring element 14 positioned within the overflow valve body 12. A screw plug 16 is positioned against a first end 18 of the spring element 14. A ball 20 is positioned against a second end 22 of the spring element 14. The ball 20 contains at least one cavity 24 to facilitate minimizing swirl that occurs within the overflow valve body 12.
[0007] In addition, a fuel metering unit is described. The fuel metering unit comprises a housing and an overflow valve body 12 integrated within the housing. A spring element 14 is positioned within the overflow valve body 12, and a screw plug 16 is positioned against a first end 18 of said spring element 14 to facilitate sealing the fuel metering unit. A ball 20 is positioned against a second end 22 of the spring element 14 and positioned within the fuel metering unit. The ball 20 contains at least one cavity 24 to facilitate minimizing swirl that occurs within the overflow valve body 12.
[0008] The fuel metering unit includes a housing. The housing includes an inlet that is in flow communication with a feed pump. The inlet is adapted to receive fuel from the feed pump. The housing of the fuel metering unit includes an outlet that is in flow communication with a high pressure pump. The fuel metering unit includes the overflow valve 10 that is integrated within the fuel metering unit. The overflow valve 10 is positioned within an opening defined within the fuel metering unit.
[0009] The overflow valve 10 comprises an overflow valve body 12 having an inlet 11 and an outlet 13. A plug 16 is disposed within the overflow valve 10. The plug 16 facilitates sealing the overflow valve 10 thereby preventing escape of fuel while the overflow valve 10 is operational. A spring member 14 is disposed within the overflow valve 10 and is in contact with the plug 16 of the overflow valve 10. A ball 20 is disposed within the overflow valve 10 and is in contact with the spring member 14 of the overflow valve 10. The ball 20 is in contact with a valve seat 21 and facilitates closing the outlet 13 while the overflow valve 10 is not operational. The spring member 14 is located in the overflow valve 10 of the fuel metering unit in a manner such that a first end 18 of the spring member 14 abuts the plug 16 while the opposite second end 22 of the spring member 14 is in contact with the ball 20.
[00010] The ball 20 includes a plurality of cavities 24 formed on an outer surface of the ball 20. In an embodiment, the ball 20 has four cavities formed on the outer surface of the ball 20. Each of the plurality of cavities 24 are formed on the outer surface of the ball 20 such that each of the plurality of cavities 24 is positioned proximate to each valve seat 21. Each of the plurality of cavities 24 that is formed on the outer surface of the ball 20 facilitates breaking up of stream lines of fuel flow that are formed on the outer surface of the ball 20 when fuel flows from the inlet 11 and around the outer surface of the ball 20. The fuel that flows around the outer surface of the ball 20 is channelled to a fuel tank via the outlet 13. In an embodiment, each of the plurality of cavities 24 are positioned symmetrically about an axis of the ball 20. In an alternate embodiment, each cavity 24 is positioned asymmetrically about an axis of the ball 20.
[00011] The principle of working of the overflow valve 10 is now explained as an example. Fuel from the feed pump is channelled to the fuel metering unit via the inlet. During this stage, the spring member 14 will be in a completely expanded state with the inlet 11 being in a closed state due to the ball 20 against the inlet 11. The spring member 14 is designed to compress, thereby opening the inlet 11 under a specific operating pressure. When the pressure of fuel entering the overflow valve 10 through the inlet 11 exceeds the specific operating pressure, the spring member 14 gets compressed. The compression of the spring member 14 causes the ball 20 to move against a force of the spring member 14, thereby causing the inlet 11 to open. Excess fuel that is channelled to the fuel metering unit from the feed pump is channelled to the outlet 13 through the inlet 11.
[00012] The fuel that is channeled through the inlet 11 flows through each of the plurality of cavities 24 of the ball 20. Due to the turbulence caused by the fuel flowing through each of the plurality of cavities 24, the swirl that is created on an upper surface of the ball 20 due to the flow of fuel around the ball 20 is minimized. Therefore, a noise level due to the swirling action of the fuel around the outer surface of the ball within the overflow valve 10 is drastically mitigated.
[00013] The above described overflow valve 10 that is integrated within the housing facilitates decreasing the lead time for manufacturing and coupling the overflow valve 10 independently to the housing of the fuel metering unit.
[00014] It must be understood that the embodiments explained in the above detailed description is only illustrative and does not limit the scope of this invention. The scope of this invention is limited only by the scope of the claims. Many modification and changes in the embodiments aforementioned are envisaged and are within the scope of this invention.