Rocker assembly having improved durability
A durable system for controlling variable valve actuation of an engine valve corresponding to a cylinder of an automobile engine. The system includes first and second crowned cams having first and second lift profiles and a rocker arm assembly. The rocker assembly includes a first arm having an end connected to said engine valve, having a high impact roller following the first crowned cam operating the engine valves according to a first lift profile. The rocker arm assembly also includes a second arm having durable slider pads riding on the second crowned cam to operate said engine valve according to a second lift profile. A latch secures the second arm relative to the first arm when in a latched position causing the valve to operate according to a second lift profile. The valve operates according to a first lift profile when the latch is not in the latched position.
1. A switching rocker arm assembly, comprising:
a first rocker arm that engages a first cam to achieve a first lift profile;
a second rocker arm that engages a second cam to achieve a second lift profile;
a dual feed hydraulic lash adjuster (DFHLA) configured to provide hydraulic switching fluid to the second arm; and
a latch adapted to have an adjustable latch lash and to secure the second rocker arm to the first rocker arm when in a latched position, wherein the second lift profile is achieved when the latch is in a latched position and the first lift profile is achieved when the latch is not in a latched position, wherein the latch is responsive to the hydraulic switching fluid to selectively move to the latched position.
2. The switching rocker arm assembly of claim 1 , wherein the switching rocker arm assembly comprises a durability exceeding an expected life of a conventional automobile engine.
3. The switching rocker arm assembly of claim 2 , wherein the expected life of the conventional automobile engine comprises a value greater than 150,000 miles.
4. The switching rocker arm assembly of claim 2 , wherein the expected life of the conventional automobile engine comprises a value greater than 200,000 miles.
5. The switching rocker arm assembly of claim 2 , wherein the expected life of the conventional automobile engine comprises a value greater than 600,000 miles.
6. The switching rocker arm assembly of claim 1 , wherein the second rocker arm comprises at least one slider pad adapted to engage the second cam.
7. The switching rocker arm assembly of claim 6 , wherein the second cam comprises a crowned cam.
8. The switching rocker arm assembly of claim 7 , wherein the second cam further comprises a steel cam.
9. The switching rocker arm assembly of claim 1 , wherein the first rocker arm comprises a roller bearing adapted to engage the first cam.
10. The switching rocker arm assembly of claim 9 , wherein the second rocker arm comprises at least one roller bearing adapted to engage the second cam.
11. The switching rocker arm assembly of claim 1 , wherein the latch is biased into one of the latched position or an unlatched position, and wherein the hydraulic switching fluid selectively moves the latch into the other of the latched or the unlatched position.
12. The switching rocker arm assembly of claim 1 , wherein the DFHLA further comprises two feed inlets, wherein hydraulic fluid pressure at a first one of the two feed inlets provides hydraulic lash adjustment, and wherein hydraulic fluid pressure at a second one of the two feed inlets provides the hydraulic switching fluid.
13. The switching rocker arm assembly of claim 12 , wherein the first one of the two feed inlets is fluidly coupled to a lower feed gallery of the DFHLA, and wherein the second one of the two feed inlets is fluidly coupled to an upper feed gallery of the DFHLA.
14. The switching rocker arm assembly of claim 13 , wherein the upper feed gallery of the DFHLA further comprises at least one passive air bleed port.
15. A switching rocker arm assembly, comprising:
a first rocker arm that engages a first cam to achieve a first lift profile;
a second rocker arm that engages a second cam to achieve a second lift profile;
a dual feed hydraulic lash adjuster (DFHLA) configured to provide hydraulic switching fluid to the second arm;
a latch adapted to secure the second rocker arm to the first rocker arm when in a latched position, wherein the second lift profile is achieved when the latch is in a latched position and the first lift profile is achieved when the latch is not in a latched position, wherein the latch is responsive to the hydraulic switching fluid to selectively move to the latched position; and
a means for adjusting a lash of the latch.
16. The switching rocker arm assembly of claim 15 , wherein the means for adjusting the lash of the latch comprises a self-aligning feature for the latch.
17. The switching rocker arm assembly of claim 15 , wherein the means for adjusting the lash of the latch comprises a means for reducing wear between contact surfaces in the assembly.
18. The switching rocker arm assembly of claim 17 , wherein the second rocker arm comprises at least one slider pad adapted to engage the second cam, and wherein the means for reducing wear between contact surfaces in the assembly further comprises the at least one slider pad coated with a multilayer wear-resistant coating including a layer exhibiting greater ductility than that of the slider pad.
19. The switching rocker arm assembly of claim 18 , wherein the means for reducing wear between contact surfaces in the assembly further comprises the at least one slider pad comprising a polished curved surface beneath the wear-resistant coating.
20. The switching rocker arm assembly of claim 18 , wherein the means for reducing wear between contact surfaces in the assembly further comprises the at least one slider pad comprising two substantially parallel curved slider pads manufactured to have less than a predetermined included angle.
21. The switching rocker arm assembly of claim 17 , wherein the second rocker arm comprises at least one slider pad adapted to engage the second cam, and wherein the means for reducing wear between contact surfaces in the assembly further comprises the second cam comprising a crowned cam.
22. The switching rocker arm assembly of claim 21 , further comprising wherein the second cam further comprises a steel cam.
23. The switching rocker arm assembly of claim 15 , further comprising a means for providing a durability of the switching rocker arm assembly that exceeds an expected life of a conventional automobile engine.
24. The switching rocker arm assembly of claim 23 , wherein the first lift profile comprises a low lift profile, and wherein the means for providing the durability further comprises a means for preventing base circle contact between the second arm and the second cam during operation of the first lift profile.
25. The switching rocker arm assembly of claim 24 , wherein the means for providing the durability further comprises the second cam having a constant velocity lift portion.
26. The switching rocker arm assembly of claim 23 , wherein the expected life of the conventional automobile engine comprises a value selected from the values consisting of: greater than 150,000 miles, greater than 200,000 miles, and greater than 600,000 miles.