Claims:We Claim:
1. A fuel injection pump (10) comprising:
- an inlet valve body (28) in fluid communication with a pump body (34), said inlet valve body (28) comprising at least one fuel flow path (26) allowing fuel flow from a fuel source to a pumping chamber (38) of said pump body (34); and a valve pin (23) located in said fuel flow path (26), said valve pin (23) adapted to be displaced along the fuel flow path (26);
characterized in said fuel injection pump (10) comprising:
a housing (12) placed on said inlet valve body (28);
a solenoid (14) located in said housing (12);
an actuator pin (16), one end of said actuator pin placed in proximity to said solenoid (14) and other end of said actuator pin (16) fitted to a casing (20), said casing located in said housing (12) ;
at least a part of said valve pin (23) of said fuel injection pump (10) extending into said housing (12) and said valve pin (12) is spring (18) loaded in said casing (20).

2. The fuel injection pump (10) as claimed in claim 1, wherein said valve pin (23) located in said fuel flow path (26) in a manner such that at least a part of the valve pin (23) extends from said fuel flow path (26) into said pumping chamber (38).
3. The fuel injection pump (10) as claimed in claim 1, wherein said spring (18) is connected between one end of the said valve pin (23) and to one surface of said casing (20).
4. The fuel injection pump (10) as claimed in claim 1, wherein said solenoid (14) and said valve pin (23) are not in direct contact with each other. , Description:Field of the invention
[0001] This invention relates to a fuel injection pump and a method thereof.

Background of the invention:
[0002] In the fuel injection system, a fuel flow control unit is placed before the fuel injection pump to control a quantity of fuel entering the fuel injection pump via an inlet valve. The basic working principle of the fuel control 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 value that is indicated by the force required to move the components of the fuel control unit. 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 its position and the fuel enters the pumping chamber of the fuel pump.
[0003] A united states patent applicaiton 20140158205 discloses a method and an apparatus for controlling a solenoid actuated inlet valve of a piston pump. A control circuit energizes the solenoid to open the inlet valve in synchronism with the reciprocation of the piston and thereafter de-energize the solenoid to initiate closure of the inlet 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 fuel injection pump according to one embodiment of the invention; and
[0006] FIG .2 illustrates a fuel injection system according to one embodiment of the invention.

Detailed description of the embodiments
[0007] Figure 1 illustrates a fuel injection pump 10 according to one embodiment of the invention. The fuel injection pump comprises an inlet valve body 28 in fluid communication with a pump body 34. The inlet valve body 28 comprises at least one fuel flow path 26 allowing fuel flow from a fuel source to a pumping chamber 38 of the pump body 34 and a valve pin 23 is located in the fuel flow path 26.The valve pin 23 is displaced along the fuel flow path 26. The fuel injection pump 10 comprises a housing 12 placed on the inlet valve body 28 and a solenoid 14 located in the housing 12.The fuel injection pump 10 comprises an actuator pin 16. One end of the actuator pin 16 placed in proximity to the solenoid 14 and other end of the actuator pin 16 fitted to a casing 20, wherein the casing is located in the housing 12.At least a part of the valve pin 23 of the fuel injection pump 10 is extending into the housing 12 and the valve pin 12 is spring 18 loaded in the casing 20.
[0008] Further details about the construction of the fuel injection pump 10 and the components of the fuel injection pump 10 will be explained in the following description. During the assembly of the fuel injection pump 10, a plunger 32 is located in a bore provided in the pump body 34. The plunger 32 is reciprocally driven into the pump chamber 38 by a rotating cam. The inlet valve body 28 is located on the pump body 34. The valve pin 23 is then inserted into the fuel flow path 26. The valve pin 23 is made from metallic material. As seen in the figure 1, the operative lower portion of valve pin 23 has a diameter which is greater than the diameter of the upper portion of the valve pin 23 that is inserted in the fuel flow path 26. Due to the difference in diameter the edge of the fuel flow path 26 which is in proximity of the pumping chamber 38, acts as the valve seat for the valve pin 23. The housing 12 is located on the inlet valve body 28. When the inlet valve body 28 is located between the housing 12 and the pump body 34, the valve pin 23 is located in the fuel flow path 26 in a manner such that at least a part of the valve pin 23 extends from the housing 12 and via the fuel flow path 26 into the pumping chamber 38.
[0009] The solenoid 14 and the actuator pin 16 are placed in the housing 12 in a manner such that the solenoid 14 and the valve pin 23 are not in direct contact with each other as shown in the figure 1. The spring 18 is connected between one end of the valve pin 23 and one surface of the casing 20.
[00010] Figure 2 illustrates a fuel injection system according to one embodiment of the invention. The fuel injection system 50 comprises a fuel source 42, a fuel filter 44, a fuel pump 10 and a common rail 46 in accordance with this disclosure. The fuel from a fuel source 42 via the fuel filter 44 enters the fuel injection pump 10 through the inlet valve 25. The fuel enters the fuel injection pump 10 through at least one fuel flow path 26. In the fuel flow path 26, the fuel enters the space along the part of the valve pin 23 which is located in the fuel flow path 26. An electronic control circuit 45 is electrically connected to the input terminals of the solenoid 14. Upon energization of the solenoid 14, the solenoid 14 operates the valve pin 23 such that, the inlet valve 25 is closed. Conversely, upon de-energization of the solenoid 14, the inlet valve 25 is made to open. An outlet valve 30 fluidly connects the pump chamber 38 of the fuel injection pump 10 to a common rail 46 of an internal combustion engine. During the operation of the fuel injection system 50, the cam 36 (which is driven by the engine) reciprocally drives the plunger 32 in the pump chamber 38.
[00011] The working of the fuel injection pump 10 is explained as follows. A map is stored in the electronic control unit 45, which has plurality of current values mapped to plurality of fuel quantities. The fuel quantity is an amount of the fuel that is allowed to enter the pump chamber 38 depending on a request from the engine. For instance, if the engine is running at a high speed and requires a maximum amount of fuel, the electronic control unit 45 upon receiving the request from an engine electronic control unit for the demand of the fuel, discontinues the supply of the current to the solenoid 14, such that, the inlet valve 25 is opened to allow fuel into the pumping chamber of the fuel pump. Upon detecting the change in the request from the engine (not shown), the electronic control unit 45 supplies current to energize the solenoid 14. The energized solenoid 14 actuates the actuator pin 16 in such a way that, the casing 20 which is attached to one end of the actuator pin 16 is pulled in an upward direction resulting in an upward movement of the valve pin 23. The spring 18 which is connected between one surface of casing 20 and the valve pin 23, gets compressed towards the casing 20, due to the upward movement of the casing 20. A movement in the valve pin 23 towards the fuel flow path 26 in the inlet valve 25, closes the inlet valve 25, thus reducing the flow of the fuel into the pump chamber 38. The fuel present in the pump chamber 38 will be pressurized and sent to the common rail 46 through the outlet valve 30 of the fuel injection pump 10.
[00012] The movement of the valve pin 23 is altered by changing the amount of current that is supplied to the solenoid 14. For instance, in one scenario, when the electronic control unit 45 supplies current (i.e., maximum current) to energize the solenoid 14, the solenoid 14 actuates the actuator pin 16 in such a way that, the actuator pin 16 pulls the casing 20 upwards which in turn pulls the valve pin 23. As the valve pin moves upwards it comes in contact with the inlet valve thereby resulting in stopping the flow of the fuel into the pump chamber 38 by closing the fuel flow path.

[00013] In another scenario, when the electronic control unit 45 supplies current (upon detecting the request for the fuel from the engine) to energize the solenoid 14, the solenoid 14 actuates the actuator pin 16 which in turn actuates the valve pin 23 in such a way that, the casing 20 along with the valve pin 25 will move in the upward direction and the movement of the valve pin 23 partially closes the inlet valve 25 thus allowing a small quantity of fuel into the pump chamber 38.

[00014] In another scenario, the electronic control unit 45 discontinues the supply of the current to the solenoid 14, when the request from the engine is detected to supply the maximum amount of fuel. The solenoid 14 is not energized and the actuator pin 16 is not actuated. The valve pin 23 will not be in contact with the inlet valve 25 and the inlet valve 25 is completely opened allowing the flow of the fuel into the pump chamber 38 via the fuel flow path 26.

[00015] With the above fuel injection pump 10 disclosed a separate fuel control unit and the hydraulic connections associated with the fuel control unit is eliminated. The inlet valve pressure is controlled with the solenoid 14 present in the housing 12. The above design provides a cost effective solution for the low cost common rail fuel injection system. With the above design, the amount of fuel flowing into the pump chamber 38 can be controlled efficiently by changing the amount of current supplied to the solenoid 14.

[00016] 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 valve used to control the flow of fuel. 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.