Development of a switching roller finger follower for cylinder deactivation in internal combustion engines
A system for selectively deactivating engine valves of a cylinder of an internal combustion engine. The system employs switching rocker assemblies between the valves of the engine and rotating cam lobes. The disclosed design is able to operate using a single cam lobe per valve. The rocker assembly employs a first arm pivotally attached to a second arm at one end. The first arm engages the valve and the second arm has a roller bearing that engages the cam lobe. A latch causes the first and second arm to move in unison following the cam surface when latched. When unlatched, the second arm follows and moves according to the rotating cam surface, but the first arm does not follow and does not actuate the valve, thereby deactivating the cylinder.
1. A rocker arm for engaging a cam having a single lift lobe, comprising:
an outer arm comprising first and second outer side arms;
an inner arm comprising at least one inner side arm and a cam-contacting member configured for transferring motion from a single lift lobe of a cam to the rocker arm, the inner arm disposed between the first and second outer side arms;
a pivot axle securing the inner arm to the outer arm, the pivot axle configured to permit pivoting movement of the inner arm relative to the outer arm about the pivot axle; and
at least one biasing spring disposed between the outer arm and the inner arm, the at least one biasing spring biasingly coupled to the cam-contacting member;
wherein the rocker arm further comprises a latch for selectively securing the inner arm relative to the outer arm thereby selectively permitting lost motion movement of the inner arm relative to the outer arm about the pivot axle;
wherein the rocker arm is fluidly coupled to a hydraulic lash adjuster, and wherein selectively applied oil pressure provided at the hydraulic lash adjuster operates the latch to selectively secure the inner arm relative to the outer arm; and
wherein the hydraulic lash adjuster comprises a dual feed hydraulic lash adjuster.
2. The rocker arm of claim 1 wherein the rocker arm further comprises a first end and a second end, the pivot axle disposed adjacent the first end, the latch disposed adjacent the second end, and the cam-contacting member disposed between the pivot axle and the latch.
3. The rocker arm of claim 2 , further comprising a valve pad mounted at one of the first end at the second end.
4. The rocker arm of claim 1 , wherein the rocker arm further comprises a first end and a second end, the pivot axle disposed adjacent the first end, the latch disposed adjacent the second end, and wherein at least a portion of the cam-contacting member is disposed between the pivot axle and the latch.
5. The rocker arm of claim 1 wherein the at least one biasing spring comprises:
at least one torsion spring secured to the outer arm and having a spring arm in biasing contact with the inner arm.
6. The rocker arm of claim 1 wherein the cam-contacting member comprises a bearing mounted on a bearing axle.
7. The rocker arm of claim 1 wherein the cam-contacting member comprises a smooth, non-rotating surface.
8. The rocker arm of claim 1 , wherein the cam-contacting member comprises a slider pad.
9. The rocker arm of claim 1 , wherein the latch is disposed adjacent a first end of the rocker arm, and where the hydraulic lash adjuster is fluidly coupled to the rocker arm at a position adjacent the first end of the rocker arm.
10. A rocker arm for engaging a cam having a single lift lobe, comprising:
an outer arm comprising first and second outer side arms;
an inner arm comprising a cam-contacting member configured for transferring motion from a single lift lobe of a cam to the rocker arm, the inner arm disposed between the first and second outer side arms;
a pivot axle securing the inner arm to the outer arm, the pivot axle configured to permit pivoting movement of the inner arm relative to the outer arm about the pivot axle;
at least one biasing spring disposed between the outer arm and the inner arm, the at least one biasing spring biasingly coupled to the inner arm;
wherein the rocker arm further comprises a latch for selectively securing the inner arm relative to the outer arm thereby selectively permitting lost motion movement of the inner arm relative to the outer arm about the pivot axle;
wherein the rocker arm is fluidly coupled to a hydraulic lash adjuster, and wherein selectively applied oil pressure provided at the hydraulic lash adjuster operates the latch to selectively secure the inner arm relative to the outer arm; and
wherein the hydraulic lash adjuster comprises a dual feed hydraulic lash adjuster.
11. The rocker arm of claim 10 , wherein the latch is disposed adjacent a first end of the rocker arm, and where the hydraulic lash adjuster is fluidly coupled to the rocker arm at a position adjacent the first end of the rocker arm.
12. The rocker arm of claim 11 , further comprising a valve pad mounted at a second end of the rocker arm.
13. The rocker arm of claim 12 , wherein the cam-contacting member is disposed between the first end and the second end.
14. The rocker arm of claim 13 , wherein the cam-contacting member further comprises a smooth, non-rotating surface.
15. The rocker arm of claim 13 , wherein the cam-contacting member further comprises a slider pad.
16. The rocker arm of claim 13 , wherein the cam-contacting member comprises a roller bearing.