Claims:We Claim:
1. A drive 100 for a high pressure fuel injection pump 102, said fuel injection pump 102 comprising at least:
plunger 104 located within housing of said fuel injection pump 102,
said plunger 104 adapted to receive motion from a cam 106 through a roller 108 and a tappet 110, characterized in that
at least one ring element 112 located axially along said cam 106; and
at least one plate 114 attached to said ring element 112;
said ring element 112 and said plate 114 enables roller 108 to follow the path of said cam 106.

2. The drive 100 for a high pressure fuel injection pump 102 of claim 1, wherein said ring element 112 is in engagement with said cam 106.

3. The drive 100 for a high pressure fuel injection pump 102 of claim 1, wherein said plate 114 is engaged to said ring element 112.

4. The drive 100 for a high pressure fuel injection pump 102 of claim 1, wherein said plate 114 establishes contact between said roller 108 and said cam 106. , Description:Field of the invention
[0001] This invention relates to the field of drive mechanism for high pressure fuel injection pump.

Background of the invention
[0002] A high pressure fuel injection pump supplies fuel to at least one injector in a fuel injection system. The fuel received in the inlet of the fuel injection pump is sent to the pressurizing chamber. The fuel is then pressurized due to reciprocating action of a plunger. A spring element in the fuel injection pump, enables the plunger to return back to its original position after delivering fuel out of the high pressure pump. The spring element is also known as the compression spring. The compression spring ensures that the drive comprising the roller, roller pin and the tappet body make contact with the cam shaft. The speed of operation of the high pressure pump is dependent on the tension in the spring. However, the speed cannot be increased infinitely, as this will lead to breakage of the spring, as the spring’s ability to compress and expand is limited. Hence in order to make fuel injection pump more efficient, there is a need to make the speed of the pump to be independent of the tension in the spring.

Brief description of the accompanying drawing
[0003] Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:

[0004] FIG. 1 illustrates a high pressure fuel injection pump with a drive; and
[0005] FIG. 2 illustrates a sectional view of the drive.

Detailed description of the embodiments
[0006] FIG. 1 illustrates a high pressure fuel injection pump 102 with a drive 100.The high pressure fuel injection pump 102 comprises at least a plunger 104 located within housing, the plunger 104 adapted to receive motion from a cam 106 through a roller 108 and a tappet 110. At least one ring element 112 is located axially along the cam 106, and at least one plate 114 is attached to the ring element 112. The ring element 112 and the plate 114 enables roller 108 to follow the path of the cam 106. The ring element 112 is in engagement with the cam 106. The plate 114 is engaged to the ring element 112.

[0007] The constructional details of the drive 100 for the high pressure fuel injection pump 102 will now be described in further detail. The reciprocating element in the high pressure fuel injection pump 102 is a plunger 104. The fuel received in the high pressure fuel injection pump 102 is pressurized by the reciprocating action of the plunger 104. The plunger 104 is located within the housing of the fuel injection pump 102. The reciprocating action of the plunger 104 is facilitated with the help of a cam 106. The cam 106 is mounted on a cam shaft 118. The cam shaft 118 derives motion from the engine. At least one ring element 112 is located axially along the cam 106. In an embodiment the ring element 112 is in engagement with the cam 106. As described in FIG. 1, a pair of ring elements 112 are located on either side of the cam 106. The ring element 112 follows the movement of the cam 106. Engaged to the ring element 112 is a plate 114. The ring element 112 encircles at least a part of the roller pin 116.The plate 114 may be engaged permanently to the ring element 112 through welding. Alternately, the plate 114 may be engaged temporarily to the ring element 112. The plate 114 ensures that the roller 108 of the high pressure fuel injection pump 102 is in contact with the cam 106 with the help of roller pin 116.The plate 114 establishes contact between the roller 108 and the cam 106.

[0008] FIG. 2 illustrates a sectional view of the drive 100. The ring element 112 encircles the roller pin 116. This is required so that there is a connection between the ring element 112 and the roller pin 116. This connection also ensures that the roller 108, along with the roller pin 116 is always in contact with the cam 106.Also, during working of the high pressure fuel injection pump 102, the rotational force of the cam 106 is transferred to the roller pin 116. The roller pin 116 in turn rotates the roller 108.

[0009] The working of the high pressure fuel injection pump 102 with the drive 100 disclosed above will now be described in detail. Fuel is received in the pressurizing chamber via the suction valve. As the fuel gets filled in the pressurizing chamber, the plunger 104 will move downwards. The plunger 104 is pressed downwards by the delivery pressure of the feed pump. The plunger 104 thus contacts the roller 108 via the tappet body. As the cam shaft 118 rotates, the cam 106 mounted on the cam shaft 118 also rotates. The ring element 112 follows the path of rotation of cam 106 and causes the roller pin 116 to rotate. The rotation of the roller pin 116 causes the roller 108 to transmit motion to the tappet 110. The tappet 110 translates and causes the plunger 104 to move upwards and away from the roller 108. The direction of translation of the tappet is along the axis of the plunger 104. The plunger 104 thus pressurizes the fuel. The pressurized fuel is then delivered through the delivery valve to the high pressure pipe. Fuel from the high pressure pipe is delivered to the injector. It should be noted that during the working of the high pressure fuel injection pump, the plate ensures that the roller always stays in contact with the cam 106 and in turn the cam shaft 118, thus obviating the need for a compression spring as used in state of art.

[00010] The reciprocating motion of the plunger 104 happens by the action of 1. Fuel entering the pressurizing chamber, and 2. Rotation of the roller 108 caused by cam 106, ring element 112 and plate 114. Thus the compression spring that is used in state of art for cause the movement of the plunger 104 is not required anymore. The spring seat that is also used in state of art is not required as the plate 114 and ring element 112 ensure that the roller 108 is always in contact with cam 106. Moreover, since the compression spring is eliminated, the torque required to drive the pump is less, as the speed of working of the fuel injection pump is now no longer dependent on the compression spring.

[00011] 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 material used in the ring element and the plate. 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.