CLIAMS:We Claim:
1. A roller tappet (10) of a high pressure pump, said roller tappet (10) comprises
a main tappet body (12);
a roller (14) and
a pin (16) supporting said roller (14), said pin (16) assembled in an opening (19) of said main tappet body (12);
characterized in that:
said main tappet body (12) comprising projections (20) at the end of the main tappet body (12) in proximity of the opening (19) provided in said main tappet body (12), said projections (20) adapted to hold said pin (16) in position.

2. The roller tappet (10) claimed in claim (1), wherein said projections (20) provided on the main tappet body (12) are such that said opening (19) can be in a semicircular shape or a c-shape or the like.
3. The roller tappet (10) claimed in claim (1), wherein said projections (20) are crimped at a predefined angle to hold said pin (16) in position.
4. The roller tappet (10) claimed in claim (1), wherein an axial and a radial movement of the pin (16) can be controlled due to said projection (20) at each side of said opening (19).
5. The roller tappet (10) claimed in claim (1), wherein a first sealing surface (30) of said projection (20) withstands a high force exerted during a forward stroke of a camshaft (22) and a second sealing surface (32) of said projection (20) withstands a low force during a return stroke of said camshaft (22).
,TagSPECI:Complete specification: The following specification particularly describes the invention and the manner in which it is to be performed.

Field of the invention
[001] This invention relates to a roller tappet of a high pressure pump.

Background of the invention
[002] High-pressure pumps of internal combustion engines have a tappet assembly with a roller in which a roller is inserted into the tappet body in the direction of the longitudinal axis with the help of a pin. The tappet body is guided in a movable manner in an engine bore or a drive box bore. The tappet assembly is driven in a reciprocating movement by a drive shaft. The high-pressure pump has a pump piston and the tappet assembly is arranged between the pump piston and a drive shaft. The drive shaft has at least one cam or eccentric on which the roller runs. The tappet assembly serves to convert the rotational movement of the drive shaft into a stroke reciprocating movement of the pump piston. The tappet assembly must reliably absorb lateral forces acting perpendicular to the axis of rotation of the roller and of the drive shaft.
[003] A German patent application 19857376 discloses a roller tappet comprising a body which has a surrounding groove with a locking ring similar to a piston ring and a hub in a roller. The roller axle rotates in the main body and the length of the roller axle, and the retaining prevents the roller axle from working loose from the hub. The locking ring retains the axle supporting the roller tappet and prevents unwanted loosening.

Brief description of the accompanying drawings
[004] Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:
[005] Figure 1 illustrates a roller tappet of a high pressure pump according to one embodiment of the invention; and
[006] Figure 2 illustrates a cross-sectional area of a roller tappet according to one embodiment of the invention.
Detailed description of the invention
[007] Figure 1 illustrates a roller tappet 10 in a high pressure pump (not shown) according to one embodiment of the invention. The roller tappet 10 comprises a main tappet body 12, a roller 14 and a pin 16 supporting the roller 14. The pin 16 is assembled in an opening 19 of the main tappet body 12. The main tappet body 12 comprises projections 20 at the end of the main tappet body 12 in proximity of the opening 19 provided in the main tappet body 12, the projections 20 adapted to hold the pin 16 in position.

[008] Figure 2 illustrates a cross-sectional area of a roller tappet 10 according to one embodiment of the invention. The projections 20 provided on the main tappet body 12 are such that the opening 19 can be in a semicircular shape or a c-shape or the like.

[009] The roller tappet 10 also comprises a bush 18 placed between the roller 14 and the pin 16. The function of the roller tappet assembly 10 is to convert a rotational motion of the camshaft 20 into a translational motion of the roller tappet assembly 10 by sliding in a specified housing or path of a drive box (not shown). The projections 20 of the main tappet body 12 is crimped / pressed to guide the pin 16 axial and the radial direction. A force (as represented by arrows in fig. 2) is applied on the projections 20 to plastically deform the projections 20 by which the pin 16 is arrested both axially and radially. The pin 16 is assembled into the opening 19 under a high temperature. Due to the high temperatures, the main tappet body 12 along the opening 19 will expand in size and the pin 16 is fitted into the opening 19.
[0010] The projections 20 are the integral part of the main tappet body 12 are crimped in a predefined angle to hold the pin 16 in a position. The aforesaid projection 20 is slightly stamped and bent inwards (as shown in figure 2). The projection 20 extends directly on to the outer surface of the pin 16. Through this measure, the pin 16 is retained from exiting axially out of the main tappet body 12, i.e., in a direction towards front end of the main tappet body. The rotational movement of the pin 16 is controlled due to the crimping angle of the projections 20 which holds the pin 16 in the constant position.

[0011] During a forward stroke of the camshaft 22 (i.e. say from 0 degrees to 180 degrees, rotating in a clock wise direction for a single lobe cam), due to the rotation of the camshaft 22, the roller 14 also experiences a linear movement in the vertical axis. The movement of the roller 14 in the main tappet body 12 moves a plunger upwards to pressurize a fuel. The pin 16 which supports the roller 14 attached at a first sealing surface 30 of the projection 20 withstands a high force developed due to high hydraulic pressure acting on the plunger and also due to a force exerted by the plunger return spring (not shown). The first sealing surface 30 of the projection 20 ensures that the contact stress developed does not cross a safety stress limit of the material by which the surface 30 is made of.
[0012] During a return stroke of the camshaft 20 (i.e., say from 180 degrees to 360 degrees), after pressurization of the fuel, the plunger returns to an initial position due to which the roller 14 moves downwards. The pin 16 along with the roller 14 moves downwards. The combined force acting on the second sealing surface 32 of the projection 20 is less due to low hydraulic pressure acting on the plunger and also due to a force exerted by plunger return spring.

[0013] With the roller tappet 10 disclosed above, the assembling of the components of the roller tappet 10 will be assembled easily. The axial movement as well as the rotational movement of the pin 16 during the working of the roller tappet 10 can be avoided. The usage of the retainer ring to limit the axial movement of the pin 16 can be eliminated with this design of the opening 19 in the main tappet body 12. With the above design, the rotational friction between the main tappet body 12 and the pin 16 can be reduced.

[0014] It must be understood that the embodiments explained in the above detailed description is only illustrative and does not limit the scope of this invention. The scope of this invention is limited only by the scope of the claims.