Engine brake camshaft lobe lubrication method

Abstract

In an engine braking system of the type wherein a cam lobe lifts a follower by direct contact, wherein the follower is at least partially contained in a brake housing containing oil. A slave piston is also at least partially contained in the brake housing, and during engine braking, movement of the follower causes the oil to move the slave piston outward. Movement of the slave piston opens an engine braking exhaust valve to open a flow path between an engine cylinder and an exhaust conduit. An oil passage through the follower is provided to lubricate an interface between a flat face of the follower and the cam lobe with oil from the brake housing. The oil passage has an outlet hole that is open on the flat face outside of the contact area between the flat face and the cam lobe.

1 . In an engine braking system of the type wherein a cam lobe lifts a follower by direct contact, wherein the follower is at least partially contained in a brake housing containing oil, and a slave piston is also at least partially contained in the brake housing, and wherein during engine braking, movement of the follower causes the oil to move the slave piston to open an engine braking exhaust valve to open a flow path between an engine cylinder and an exhaust conduit, the improvement comprising:
 providing an oil passage through the follower to lubricate an interface between a flat face of the follower and the cam lobe with oil from the brake housing.   
     
     
         2 . The improvement according to  claim 1 , wherein the oil passage has an outlet hole that is open on the flat face outside of the contact area between the flat face and the cam lobe. 
     
     
         3 . The improvement according to  claim 2 , wherein the oil passage extends axially through the follower with a first portion and then with a second portion extending obliquely from the flat face to intersect with the first portion. 
     
     
         4 . The improvement according to  claim 3 , wherein an angle between the first portion and the second portion is about 145 degrees. 
     
     
         5 . The improvement according to  claim 2 , wherein the oil passage includes a first linear portion that extends from an end of the follower along a first direction to an intersecting position within the follower and a second linear portion that extends from the flat face to intersect the first linear portion at the intersecting position, the first and second portions being non-collinear. 
     
     
         6 . The improvement according to  claim 5 , wherein the first linear portion has a greater diameter than the second linear portion. 
     
     
         7 . In an engine having a cam with cam lobes and a plurality of cam followers riding on respective cam lobes, the improvement comprising:
 providing an oil passage through each of the followers to lubricate an interface between a flat face of each follower and a respective cam lobe, the oil passage comprising an outlet hole on the flat face that is outside the contact area between the flat face and the cam lobe.   
     
     
         8 . The improvement according to  claim 7 , wherein the oil passage comprises an axial portion extending from an end of the follower opposite the flat face and an oblique portion extending from the outlet hole to the axial portion. 
     
     
         9 . The improvement according to  claim 8 , wherein an angle between the axial portion and the oblique portion is about 145 degrees. 
     
     
         10 . The improvement according to  claim 8 , wherein the axial portion has a diameter that is greater than the oblique portion. 
     
     
         11 . The improvement according to  claim 7  wherein the oil passage has an inlet hole that is open to a source of pressurized oil. 
     
     
         12 . The improvement according to  claim 11 , wherein each follower is at least partially contained within a brake housing that contains pressurized oil, and the pressurized oil is delivered to the interface through the inlet hole and the outlet hole of the oil passage.