Claims:We Claim

1. A fuel injection pump (10), said fuel injection pump (10) comprising:
a fuel inlet supply path (12), a first end of the fuel inlet supply path (12) in flow communication with a fuel tank, and an opposite second end of the fuel inlet supply path (12) in flow communication with a pumping chamber and an overflow supply path (14) of the fuel injection pump (10), the fuel inlet supply path (12) adapted to supply pressurized fuel from the fuel tank to the pumping chamber and to the overflow supply path (14);
a first end of the overflow supply path (14) in flow communication with the fuel inlet supply path (12) via a shaft sealing ring, an opposite second end of the overflow supply path (14) in flow communication with the fuel tank and adapted to deliver excess pressurized fuel from the fuel inlet supply path (12) to the fuel tank via the overflow supply path (14); and
a valve seat (16) defined in the overflow supply path (14) and equipped with a ball (18) of a spherical valve element, said valve seat (16) formed on the valve chamber such that the ball (18) of the spherical valve element fits snugly on said valve seat (16) thereby preventing a flow of fuel from the second end of the overflow supply path (14) to the shaft sealing ring.

2. An overflow supply path (14) for a fuel injection pump (10), said overflow supply path (14) comprising:
a valve chamber comprising a first portion (20) and a second portion (22), said first portion (20) having a larger diameter than said second portion (22), said valve chamber comprising a valve seat (16) defined in the valve chamber between said first portion (20) and said second portion (22) and equipped with a ball (18) of a spherical valve element, said valve seat (16) formed on the valve chamber such that the ball (18) of the spherical valve element fits snugly on said valve seat (16) thereby preventing a flow of fuel from the first portion (20) of the valve chamber to the second portion (22) of the valve chamber
, 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] This invention relates to a fuel injection pump, and more specifically to a ball valve for preventing a flow of fuel into the fuel injection pump.

Background of the invention
[0002] JP Patent Application Number 2004138002 A describes a fuel filter device. To solve a problem that the manufacturing cost is increased to surely prevent a back flow of fuel by providing a commercially available manual opening/closing valve and solenoid opening/closing valve at two places of (1) a halfway part of a bypass circuit which communicates with a fuel pressure-feeding route from a fuel tank to a fuel filter device, and a fuel return route from a fuel injection pump to the fuel tank, and (2) a halfway part of the fuel pressure-feeding route from the fuel filter device to the fuel injection pump in the fuel filter device. The fuel filter device is interposed in the fuel pressure-feeding route between the fuel tank and the fuel injection pump. The fuel filter device is provided with a backflow prevention valve equipped with a ball of a spherical valve element, a valve chamber housing the valve element, and a valve seat formed on a valve chamber end part in the fuel pressure-feeding route between the fuel filter device and the fuel injection pump.

Brief description of the accompanying drawing
[0003] Figure 1 illustrates a schematic diagram of a fuel injection pump illustrating the valve element in one embodiment of the invention.

Detailed description of the embodiments
[0004] Figure 1 illustrates a schematic diagram of a fuel injection pump 10 illustrating the valve element in one embodiment of the invention. The fuel injection pump 10 comprises a fuel inlet supply path 12, a first end of the fuel inlet supply path 12 in flow communication with a fuel tank, and an opposite second end of the fuel inlet supply path 12 in flow communication with a pumping chamber and an overflow supply path 14 of the fuel injection pump 10. The fuel inlet supply path 12 is adapted to supply pressurized fuel from the fuel tank to the pumping chamber and to the overflow supply path 14. A first end of the overflow supply path 14 is in flow communication with the fuel inlet supply path 12 via a shaft sealing ring, an opposite second end of the overflow supply path 14 in flow communication with the fuel tank and adapted to deliver excess pressurized fuel from the fuel inlet supply path 12 to the fuel tank via the overflow supply path 14. A valve seat 16 is defined in the overflow supply path 14 and equipped with a ball 18 of a spherical valve element, the valve seat 16 formed on the valve chamber such that the ball 18 of the spherical valve element fits snugly on the valve seat 16 thereby preventing a flow of fuel from the second end of the overflow supply path 14 to the shaft sealing ring.

[0005] The fuel injection pump 10 comprises a fuel inlet supply path 12. A first end of the fuel inlet supply path 12 is in flow communication with a fuel tank. More specifically, the first end of the fuel inlet supply path 12 is in flow communication with the fuel tank and is adapted to channel fuel from the fuel tank to a pumping chamber of the fuel injection pump 10. An opposite second end of the fuel inlet supply path 12 is in flow communication with a pumping chamber and an overflow supply path 14 of the fuel injection pump 10. In the exemplary embodiment, the fuel inlet supply path 12 is adapted to supply pressurized fuel from the fuel tank to the pumping chamber and the excess pressurized fuel to the overflow supply path 14.

[0006] In the exemplary embodiment, a first end of the overflow supply path 14 is in flow communication with the fuel inlet supply path 12 via a shaft sealing ring. More specifically, the shaft sealing ring is positioned between the overflow supply path 14 and the fuel inlet supply path 12 and receives fuel that is supplied from the fuel inlet supply path 12. Therefore, the flow of fuel from the fuel inlet supply path 12 to the fuel outlet supply path 14 via the shaft sealing ring will lubricate the shaft sealing ring, and will not damage the components of the shaft sealing ring. An opposite second end of the overflow supply path 14 is in flow communication with the fuel tank and is adapted to deliver excess pressurized fuel from the fuel inlet supply path 12 to the fuel tank via the overflow supply path 14.

[0007] In the exemplary embodiment, a valve seat 16 is defined in the overflow supply path 14 and equipped with a ball 18 of a spherical valve element. The valve seat 16 that is formed on the valve chamber is formed such that the ball 18 of the spherical valve element fits snugly on the valve seat 16, thereby preventing a flow of fuel from the second end of the overflow supply path 14 to the shaft sealing ring. More specifically, since the ball 18 of the spherical valve element fits snugly on the valve seat 16, the fuel cannot flow from the second end of the overflow supply path 14 to the shaft sealing ring via the ball 18 of the spherical valve element. This prevents the shaft sealing ring from getting damaged if the second end of the overflow supply path 14 is in flow communication with the fuel tank, and fuel is channeled from the fuel tank through the second end of the overflow supply path 14 in the direction of the shaft sealing ring.

[0008] A working of the fuel injection pump 10 is described as an example. A first end of the overflow supply path 14 is in flow communication with the shaft sealing ring, while the opposite second end of the overflow supply path 14 is in flow communication with the fuel tank and adapted to deliver excess pressurized fuel from the fuel inlet supply path 12 to the fuel tank via the overflow supply path 14. The valve seat 16 that is formed on the valve chamber is formed such that the ball 18 of the spherical valve element fits snugly on the valve seat 16, thereby preventing a flow of fuel from the second end of the overflow supply path 14 to the shaft sealing ring. More specifically, since the ball 18 of the spherical valve element fits snugly on the valve seat 16, the fuel cannot flow from the second end of the overflow supply path 14 to the shaft sealing ring via the ball 18 of the spherical valve element. This prevents the shaft sealing ring from getting damaged if the second end of the overflow supply path 14 is connected to the fuel tank, and fuel is channeled from the fuel tank through the second end of the overflow supply path 14 in the direction of the shaft sealing ring. More specifically, the ball 18 of the spherical valve element firmly closes the path of fuel to the shaft sealing ring, and prevents the flow of fuel from the second end of the overflow supply path 14 to the shaft sealing ring.

[0009] 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 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.