Claims:We Claim:
1. A delivery valve (200) for a fuel injection pump, said delivery valve 200 located on valve body (202) of said fuel injection pump and comprises:
a pin 204, said pin 204 comprising a head 208, and
a ring element 206 located proximal to said head 208 and surrounding said pin 204; characterized in that:
said ring element 206 comprises a notch 210 formed on periphery of said ring element 206.

2. The delivery valve (200) of claim 1, wherein said notch 210 is any one of a triangular and rectangular notch.

, 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 the field of delivery valve for a fuel injection pump.

Background of the invention
[0002] FIG. 1 illustrates a delivery valve for a fuel injection pump as per the state of art. A fuel injection pump is used to pressurize fuel before the fuel reaches the injector. In order to pressurize the fuel, the fuel injection pump comprises a pressurizing chamber 102 that receives fuel from the fuel tank via an inlet 103. A reciprocating plunger 104 pressurizes the fuel and once the fuel develops pressure it lifts a delivery valve pin 106. The delivery valve pin 106 lifts when the pressure of the fuel is sufficient to overcome the pre-load exerted by the spring 108 located in the delivery valve holder of the fuel injection pump. The delivery valve pin 106 comprises a ring element 110, a portion of the ring element comprises a flat that 112 is formed by grinding process. The function of the flat 112 is to allow an additional amount of fuel to pass through the opening that is created due to the presence of flat during low speed conditions. The flat 112 on the ring element 110 reduces the area of ring element hence creating an opening with respect to the delivery valve holder as disclosed in FIG. 1. Since the flat is created after heat treatment and with grinding, this process adds to the overall cost of the delivery valve pin 106.

[0003]Prior art patent application GB444346A discloses a delivery valve for a fuel injection pump comprises a ball or other valve arranged in a passage which permits a restricted flow of fuel. The passage is of larger diameter at so that a full flow of fuel is permitted. The arrangement allows a release of pressure in the delivery pipe during closing of the valve. An adjustable stop limits the lift of the valve and ports are provided for the flow. In a modification the passage is the same diameter throughout but flutes are provided in the end remote from the seat. The abutment may be replaced by adjustable spring loading of the valve.

Brief description of the accompanying drawing
[0004] Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:

[0005] FIG. 1 illustrates a delivery valve for a fuel injection pump as per the state of art; and

[0006] FIG. 2 illustrates a delivery valve for a fuel injection pump according to an embodiment of the invention.

Detailed description of the embodiments
[0007] FIG. 2 illustrates a delivery valve 200 for a fuel injection pump according to an embodiment of the invention. The delivery valve 200 is located on a valve body 202 of the fuel injection pump and comprises a pin 204, the pin 204 comprises a head 208. A ring element 206 is located proximal to the head 208, the ring element 206 surrounds the pin 204. The ring element 206 comprises a notch 210 formed on periphery of the ring element 206. In an embodiment the notch 210 may be a triangular notch or a rectangular notch.

[0008]The construction of the delivery valve 200 with respect to the fuel injection pump will be explained in further detail. For the purpose of better understanding the construction of the fuel injection pump will be explained first, followed by the construction and position of the delivery valve 200. The fuel injection pump is used to pressurize fuel that is received from a fuel tank. Fuel from the fuel tank flows through a pipe (not shown) and reaches the inlet 203 of the fuel injection pump. From the inlet 203 fuel enters the pressurizing chamber 209. A reciprocating plunger 207 pressurizes the fuel present in the pressurizing chamber 209. The plunger 207 may be driven by a cam (not shown), the cam derives power from an engine (not shown). The pressurizing chamber 209 is created with the help of the valve body 202. The gap between the valve body 202 and the plunger 207 represents the pressurizing chamber 209. The volume in the pressurizing chamber 209 varies due to movement of plunger 207.

[0009] Moving further the construction of the delivery valve 200 will be explained in further detail. The delivery valve 200 is located on the valve body 202. The valve body 202 is located on the fuel injection pump. The valve body 202 aligns the delivery valve 200 with respect to the pressurizing chamber 209. The delivery valve 200 comprises a pin 204, the pin 204 comprises the head 208. A spring 205 is supported on the head 208, the stiffness of the spring 205 is such that the delivery valve 200 compress the spring 205 when the pressure of fuel in the pressurising chamber 209 exceeds the spring 205 pre-load. The ring element 206 is located proximal to the head 208 and surrounds the pin 204. The ring element 206 comprises a notch 210 formed on periphery of the ring element 206. The notch 210 may be formed by embossing method or rolling method. The dimension of the notch (angle and depth of notch) is defined and controlled based on hydraulic behavior requirement of fuel injection pump which in-turn depends on engine configuration. Hence by varying the dimensions of the notch the delivery valve 200 may be used on different varieties of fuel injection pump.

The function of the notch 210 is to allow additional amount of the fuel from the pressurizing chamber 209 to flow through the delivery valve 200, for example, during low speed condition.

[0010]The working of the delivery valve 200 in the fuel injection pump will be explained in further detail. Initially when the engine is cranked for the first time during start, the speed of the engine will be lower in comparison to the speed when the engine is running under full throttle. There may be time lag for the pressure to build up in the fuel injection pump and for the pressurized fuel to inject fuel from the fuel injector, this time lag may lead to engine stall. In order to overcome the additional frictional forces during start and low speeds, an additional quantity (in comparison to the quantity of fuel that flows when the delivery valve 200 opens) of fuel flows through the notch 210 of the delivery valve 200, this fuel flows during the time when the pressure starts to build up in the pressurizing chamber 209. Once the pressure of fuel exceeds the pre-load exerted by the spring 205, the delivery valve 200 moves against (compresses the spring) and opens the path for fuel to flow through the valve body 202.

[0011] By having a notch 210 in the delivery valve 200, it is now possible to avoid the additional grinding process post heat treatment of the delivery valve 200 that is required for creation of a flat as disclosed in state of art. This brings down the cost of delivery valve 200.

[0012]It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention in terms of the type of fuel injection pump used. 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.