Rocker arm assembly and components therefor
A method of precision manufacture of an outer arm of a rocker arm assembly is performed by determining structures of a rough outer arm that would require precision processing and locations to support the structures as they are processed. Starting with at least one structure requiring precision processing, locations on the outer arm close to the structure to hold the outer arm during processing are determined that would cause minimal distortion of the outer arm during processing. The outer arm is then provided with clamping lobes at these locations. The clamping lobes of the outer arm are clamping into a fixture for manufacturing. The slider pad may now be precision ground while the outer arm is clamped in the fixture with minimal risk of distortion of the outer arm.
1. A method of precision manufacture of an outer arm of a rocker arm assembly comprising the steps of:
identifying at least one structure of the outer arm requiring precision processing;
determining locations on the outer arm close to the at least one structure requiring the precision processing to hold the outer arm during the precision processing to cause minimal distortion of the outer arm during the precision processing;
providing an outer arm with clamping lobes at the determined locations;
clamping the outer arm at the clamping lobes in a fixture; and
precision processing the at least one structure while the outer arm is clamped in the fixture.
2. The method of claim 1 wherein the at least one structure requiring the precision processing comprises slider pads.
3. The method of claim 1 wherein the precision processing includes grinding of the slider pads.
4. The method of claim 3 , further comprising polishing the slider pads.
5. The method of claim 1 wherein the slider pads form an upper portion of the outer arm.
6. The method of claim 1 wherein the clamping lobes are located under each of the slider pads.
7. The method of claim 1 , wherein the precision processing includes grinding the slider pads to a flat finish.
8. The method of claim 7 , further comprising applying a diamond-like carbon coating (DLC) to the slider pads after the step of polishing.
9. A method of precision manufacture of an outer arm of a rocker arm assembly comprising the steps of:
casting an outer arm of a rocker arm assembly, the cast outer arm comprising separate left and right side arms;
clamping the outer arm via a clamping lobe on a bottom surface of each of the left and right side arms; and
precision processing the outer arm while the outer arm is clamped via the clamping lobes,
wherein the step of precision processing comprises forming a slider pad on a top surface of each of the left and right side arms and wherein clamping the outer arm via the clamping lobes reduces distortion of the outer arm caused by the precision processing.
10. The method of claim 9 , wherein the clamping lobes of the left and right side arms are directly under the slider pads of the left and right side arms.
11. The method of claim 9 , wherein the precision processing comprises grinding the slider pads.
12. The method of claim 11 , wherein the precision processing further comprises polishing the slider pads after the step of grinding.
13. The method of claim 12 , further comprising applying a diamond-like carbon coating (DLC) to the slider pads after the step of polishing the slider pads.
14. The method of 12 , wherein the step of polishing the slider pads comprises a technique selected from the group consisting of vapor honing and fine particle sandblasting.
15. A method of precision manufacture of an outer arm of a rocker arm assembly comprising the steps of:
casting an outer arm of a rocker arm assembly, the cast outer arm comprising separate left and right side arms suitable for forming slider pads on a top surface of the left and right side arms;
clamping the outer arm via a clamping lobe on a bottom surface of each of the left and right side arms, the clamping lobes located directly beneath areas suitable for forming slider pads on the left and right side arms; and
grinding the outer arm while the outer arm is clamped via the clamping lobes, the grinding forming slider pads on the left and right side arms and wherein clamping the outer arm via the clamping lobes reduces distortion of the outer arm caused by the grinding.
16. The method of claim 15 , wherein the ground slider pads satisfy a flatness standard between the slider pad on the left side arm and the slider pad on the right side arm, the flatness standard selected from the group consisting of: less than 0.05 degree included angle; less than 0.2 degree included angle; and less than 0.4 degree included angle.
17. The method of claim 15 , further comprising polishing the slider pads.
18. The method of claim 17 , further comprising applying a diamond-like carbon coating to the polished slider pads.
19. The method of claim 18 , wherein the step of applying the diamond-like carbon coating to the polished slider pads comprises:
applying an adhesion layer to the polished slider pads;
applying a ductile layer to the adhesion layer;
applying a low-friction intermediate layer to the ductile layer; and
applying a low friction hard functional layer to the low friction intermediate layer.
20. The method of claim 18 , wherein the DLC coating is between 2 and 6 micrometers thick.