Field of the invention
[0001] This invention relates to a roller tappet in a vehicle. The invention more
particularly relates to a design of a bearing ring in the roller tappet.
Background of the invention
[0002] A roller-tappet is used for transmitting drive force received from the cam actuator to the plunger in the plunger-barrel assembly. The tappet-body of the roller-tappet rotates due to thrust forces. The typical roller tappet has a cylindrical body with a bifurcated portion at one end for receiving the roller and its associated shaft. The roller follows a cam causing the tappet to reciprocate in a bore of the engine block. The movement of the tappet controls the movement of an associated valve. In order to increase the flow of oil for adequate lubrication, conventional valve tappets have provided a centralized groove machined circumferentially into a portion of the tappet body.
[0003] A Prior art document DE3933119 discloses a bearing pin in the form of a ball race rolled out to a circle from a steel strip and incorporated into a radial roller bearing. Its length is larger than the axial length of the radial roller bearing. The two bearing pin ends stick out from the radial roller bearing. The bearing pin has at least one cavity starting from one end of the bolt. The cavity is next to the welding seam along which may be spaced apart radial holes.
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 roller tappet in a vehicle in accordance with one
embodiment of the invention;
[0006] Fig.2 illustrates a bearing ring of the roller tappet in a vehicle.

Detailed description of the embodiments
[0007] Fig.1 illustrates a roller tappet 10 in a vehicle, in accordance with one embodiment of the invention. The roller tappet 10 comprises a roller tappet body 12 comprising at least two roller tappet legs 14 and a bearing ring 16 inserted into the two roller tappet legs 14. The bearing ring 16 is positioned perpendicular to the roller tappet body 12 in the roller tappet 10. The roller tappet 10 comprises a roller 18 mounted on the bearing ring 16 and a top portion of the roller 18 is in contact with a bottom portion of the roller tappet body 12. The roller tappet 10 further comprises a retainer ring 22 enclosed on a first groove 24 of the bearing ring 16. The retainer ring 22 is adapted to lock the bearing ring 16 in one of the roller tappet legs 14. The roller tappet 10 further comprises at least one second groove 26 formed on an outer surface of the bearing ring 16.At least one second groove 26 is perpendicular to the first groove 24.
[0008] Further the construction of the roller tappet 10 and the components of the roller tappet 10 are explained as follows. A bottom portion of the roller tappet 10 is connected to a camshaft (not shown) and a top portion is connected to a plunger (not shown) of a high pressure pump (not shown). The roller tappet legs 14 formed at the bottom portion of the roller tappet 10, are identical. The bearing ring 16 is inserted into the roller tappet legs 14 and is locked with the retainer ring 22 as known to a person skilled in the art. The retainer ring 22 is present in any of the tappet legs 14 adapted to lock the bearing ring 16 in an intact position.
[0009] The roller tappet 10 further comprises at least one flow path 20 through which a lubrication liquid is made to flow onto the bearing ring 16. According to one embodiment of the invention, two flow paths 20 are made on each side of the roller tappet 10 above the first groove 24 of the roller tappet 10 as shown in the

figure 1. The roller 18 and the bearing ring 16 is positioned in such a way that, the clearance area will be small between the roller 18 and the bearing ring 16. According to one embodiment, the clearance area between the roller 18 and the bearing pin 16 is less than 50 microns.
[0010] Figure 2 illustrates the bearing ring 16 of the roller tappet 10. At least one second groove 26 is made, from the first groove 24 to an end of the bearing ring 16. The number of the second grooves 26 that are made on the outer surface of the bearing ring 16 varies from a minimum of one to maximum of four. However, the number of the second grooves 26 is not restricted, however, depending on the roller 18 and the bearing pin 16 dimensions, the number of the second grooves 26 made on the surface of the bearing ring 16 is varied. The first groove 24 is made along a circumference of the bearing ring 16 and wherein at least one-second groove 24 is made in axial direction on the bearing ring 16.
[0011] A volume of the first groove 24 and at least one second groove 26 are same according to one embodiment of the invention. According to another embodiment of the invention , the volume of the first groove 24 and at least one second groove 26 are different. The amount of lubrication liquid flowing into the first groove 24 and the second groove 26 can be of the same quantity or the different quantity based on the requirement.
[0012] A method of working of the roller tappet 10 is explained as follows. The camshaft is adapted to operate the roller tappet 10, to move the plunger in a radial direction . During the working of the roller tappet 10, the roller 18 rotates in in the radial direction (as the roller 18 is constrained to move in the axial direction), to move the plunger. Since the clearance area between the roller 18

and the bearing ring 16 being minimum, a portion of the roller 18 ruptures against a portion of the bearing ring 16. The friction developed between the roller 18 and the bearing pin 16 wears the contact surface of the roller 18 and the bearing pin 16.
[0013] To reduce this wear, the lubricating liquid is made to flow into the roller tappet 10, to lubricate the bearing ring 16. The lubricating liquid is made to flow into the first groove 24 via the lubrication hole or at least one flow path 20. The flow of the lubrication liquid into the first groove 24 lubricates the circumference of the bearing ring 16 (the area where the retainer ring 22 is positioned). From the first groove 24, the lubricating liquid flows into at least one of the second groove 26, thus, lubricating the complete bearing ring 16, during the working of the roller tappet 10. Since, multiple grooves 26 are made on the bearing ring 16, the lubricating liquid is adapted to flow into the corresponding second groove 26 which comes into contact with the first groove 24 during the operation of the roller tappet 10.
[0014] With the above-disclosed roller-tappet 10, the lubrication oil is made to flow into the first groove 24 and then into at least second groove 26 for a complete lubrication of the bearing ring 16 , such that, the wear at a portion of the bearing ring 16 that is in contact with the roller 18 can be reduced. The heat developed between the bearing ring 16 and the roller tappet 10 is efficiently dissipated with the above-disclosed bearing ring 16 design. The above invention provides a cost-effective solution, since, the use of the extra components are avoided.

[0015] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. 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.

1. A roller tappet (10) in a vehicle, said roller tappet (10) comprising :
- a roller tappet body (12) comprising at least two roller tappet legs (14);
- a bearing ring (16) inserted into said two roller tappet legs (14), such that, said bearing ring (16) is positioned perpendicular to said roller tappet body (12);
- a roller (18) mounted on said bearing ring (16) , a top portion of said roller (18) is in contact with a bottom portion of said roller tappet body (12);
- a retainer ring (22) enclosed on a first groove (24) of said bearing ring (16), and adapted to lock said bearing ring (16) in any one of said roller tappet legs (14) ;
characterized in that :
- at least one second groove (26) is formed on an outer surface of said
bearing ring (16), such that, said at least one second groove (26) is
perpendicular to said first groove (24).
2. The roller tappet (10) as claimed in claim 1, wherein said at least one second groove (26) is formed from said first groove (24) to an end of said bearing ring (16).
3. The roller tappet (10) as claimed in claim 1, wherein said first groove (24) is made along a circumference of said bearing ring (16) and said at least one second groove (26) is made in axial direction on said bearing ring (16).

4. The roller tappet (10) as claimed in claim 1, wherein a lubricating liquid is adapted to flow from said first groove (24) into said at least one second groove (26) during the working of said roller tappet (10).
5. The roller tappet (10) as claimed in claim 1, wherein a volume of said first groove (24) and at least one second groove (26) are same.
6. The roller tappet (10) as claimed in claim 1, wherein a volume of said first groove (24) and at least one second groove (26) are different from each other.