CLIAMS:CLAIMS
We Claim:
1. A fuel injection pump (300), comprising:
a pumping unit (302a) for pressurizing fuel, the pumping unit comprising:
a plunger (220);
a delivery valve pin (214); and
characterized in that, a barrel unit (402) receives the plunger (220), the barrel unit (402) comprises a first section (502), wherein the first section (502) is adapted for positioning the delivery valve pin (214).

2. The fuel injection pump (300) in accordance with claim 1, wherein the barrel unit (402) further comprises a valve seat (404) at the first section (502) for positioning the delivery valve pin (214).
3. The fuel injection pump (300) in accordance with claim 1, wherein the first section (502) of the barrel unit (402) has an internal diameter (D1) in accordance with the diameter of the delivery valve pin (214).
,TagSPECI:Field of the invention
[001] The present invention relates to a fuel injection pump. More specifically, to the fuel injection pump for a diesel fuel injection system.

Background of the invention
[002] Fuel injection pumps for the diesel fuel injection system can be of single cylinder or multi-cylinder type. In other words the fuel injection pump can comprise one or more pumping units. The number of pumping units in a fuel injection pump is decided based on number of cylinders on the engine.

[003] Each pumping unit of the fuel injection pump comprises a plunger while reciprocating within the pumping unit, pressurizes the fuel. A component aligning the plunger linearly is called a barrel. In order to hold a delivery valve pin of the pumping unit, a separate component such as a holder may be used.

Summary of the invention
[004] In one aspect of the present invention, a fuel injection pump is provided. The fuel injection pump includes a pumping unit for pressurizing fuel with a plunger, a delivery valve pin, and characterized in that, a barrel unit receives the plunger; the barrel unit comprises a first section, wherein the first section is adapted for positioning the delivery valve pin. The barrel unit further comprises a valve seat at the first section for positioning the delivery valve pin. The first section of the barrel unit has a diameter (D1) in accordance with the diameter of the delivery valve pin.

Brief description of the accompanying drawings
[005] Figure 1 illustrates a fuel injection pump used in diesel fuel injection systems.
[006] Figure 2 is a cross sectional view of one of the pumping units of the fuel injection pump.

[007] Figure 3 is a fuel injection pump in accordance with an embodiment of the present invention.

[008] Figure 4 illustrates one of the pumping units of the fuel injection pump in accordance with one embodiment of the present invention.

[009] Figure 5 illustrates a barrel unit used in one of the pumping units of the fuel injection pump in accordance with an embodiment of the present invention.

Detailed description of the embodiments

[0010] Figure 1 illustrates a conventional fuel injection pump 100 used in diesel fuel injection systems.

[0011] The conventional fuel injection pump 100 as illustrated in the figure is an in-line fuel injection pump. The conventional fuel injection pump 100 includes one or more pumping units 102 aligned in series to pressurize the fuel from a reservoir (not shown in the figure). Section 106 illustrates a cross sectional view of the one of the one or more pumping units 102 of the conventional fuel injection pump 100.

[0012] Figure 2 is a cross sectional view of one of the pumping units, 102a of the conventional fuel injection pump 100.

[0013] The pumping unit 102a of the conventional fuel injection pump 100 includes an outlet 202, a first pressure valve member 206, a second pressure valve member 208, a third pressure valve member 210, a pressure valve holder 212, a delivery valve pin 214, a delivery valve holder 216, a barrel 218, and a plunger 220.
[0014] The outlet 202 of the pumping unit 102a releases a high pressure fuel delivered during the upward stroke of the plunger 220. It may be noted from the figure, the pumping unit 102a of the conventional fuel injection pump 100 has the delivery valve holder 216 and the barrel 218 to be two different components. The barrel 218 includes an inlet port 224 connecting a fuel gallery 226 and the pumping unit 102a. Further, sealing surface is present at the contact surface between the pressure valve holder 212 and the delivery valve holder 216. For example, a soft sealing surface such as a copper washer could be used for sealing the gap between the pressure valve holder 212 and the delivery valve holder 216. The sealing between the delivery valve holder 216 and the barrel 218 could be hard sealing, for example, no bushing or washer is provided.

[0015] More importantly, in the prior art explained herein, the delivery valve holder 216 and the barrel 218 are two separate components. Increase in number of components results in increasing manufacturing steps. Further, in the in-line fuel injection pumps, due to the high pressure of the fuel within the pumping unit 102a of the conventional fuel injection pump 100, sealing may be required between the delivery valve holder 216 and the barrel 218. It may increase the total cost of the fuel injection pump and undue burden of maintenance.

[0016] Further, a step 222 in the barrel 218 contributes to an additional manufacturing step. The step 222 may be provided to withstand the buckling load exerted on the barrel 218.

[0017] Figure 3 is a fuel injection pump 300 in accordance with an embodiment of the present invention.

[0018] The fuel injection pump 300 includes one or more pumping units 302 aligned in-line to create required pressure in the fuel circuit of the fuel injection system. Section 304 shows cross sectional view of one of the one or more pumping units 302, 302a.

[0019] Figure 4 illustrates one of the pumping units 302a of the fuel injection pump 300 in accordance with one embodiment of the present invention.
[0020] In accordance with one embodiment, the fuel injection pump 300 includes a plunger 220, a delivery valve pin 214 and characterized in that, the fuel injection pump 300 includes a barrel unit 402 receiving the plunger 220, and the barrel unit 402 comprises first section 502 with a valve seat 404 for assisting in positioning the delivery valve pin 214. In an embodiment, the delivery valve pin 214 is a pin. It can be observed from the figure 4, a single body, the barrel unit 402 is adapted to receive and position the delivery valve pin 214 as well as include the inlet port 224. It may be noted that, having the single body which is the barrel unit 402 for holding or positioning the delivery valve pin 214 reduces number of parts in the pumping unit 302a in the fuel injection pump 300 when compared with the pumping unit 102a of the conventional fuel injection pump 100. Both numbers of manufacturing steps involved and the product maintenance requirement may be reduced by using the barrel unit 402 in the pumping unit 302a in accordance with the present embodiment. Further, usage of sealing surface is also reduced in the pumping unit 302a compared to the pumping unit 102a. Furthermore, usage of the barrel unit 402 eliminates the then major problem of fretting between components. The components 216 and 218 of the pumping unit 102a experienced fretting because of hard sealing under high pressure. Hence, in accordance with the present embodiment, the design and utility of the barrel unit 402 solves a technical problem that existed in the pumping unit 102a of the conventional fuel injection pump 100.

[0021] Figure 5 illustrates the barrel unit 402 used in one of the pumping units, 302a of the fuel injection pump 300 in accordance with an embodiment of the present invention.

[0022] In an embodiment of the present invention, the barrel unit 402, as a single body includes a first section 502 and a second section 504. The first section 502 includes the valve seat 404 for positioning the delivery valve pin 214. The valve seat 404 has an inclined surface to position the delivery valve pin 214. The second section 504 receiving the plunger 220 includes the inlet port 224 which connects the pumping unit 302a to the fuel gallery 226. It may be noted that, the first section 502 has an internal diameter (D1) that is in accordance with the diameter of the delivery valve pin 214 and the second section 504 has a second internal diameter (D2) that is in accordance with the diameter of the plunger 220. In other words, the first section 502 holds the delivery valve pin 514 and the second section 504 receives the plunger 220. Hence, in an exemplary embodiment, the barrel unit 402 internally includes a step 506 as shown in the figure where the first section 502 ends and the second section 504 begins.

[0023] In accordance with embodiments of the present invention, the barrel unit 402 not only receives and aligns the plunger 220 of the pumping unit 302a, but also capable of receiving and positioning the delivery valve pin 214. A person skilled in the art may also envisage miniscule modifications from the illustrations of the barrel unit 402 of the fuel injection pump 300. However, the scope of the invention is to be interpreted only from the claims appended herein.