Low friction switching roller finger follower for high valve lift

Abstract

A switching roller finger follower for valve actuation comprises a pair of outer arms comprising an axle mounting. A bridge portion joins the pair of outer arms. A latch assembly comprises a ferrule. The ferrule is configured to reciprocate in a latch recess. An inner arm is pivotably mounted to a main axle and comprises a bearing rotatably mounted to a bearing axle. The bearing is configured to transfer forces from a cam lobe to the inner arm. A catch on the inner arm is configured to latch against the lip when the ferrule is in a first position. The catch can pivot past the ferrule when the ferrule is in a second position.

1 . A switching roller finger follower for valve actuation, comprising:
 a pair of outer arms configured to transfer forces from a pair of outer cam lobes, the pair of outer arms comprising respective axle mountings;   a bridge portion joining the pair of outer arms, the bridge portion comprising a first spring seat opposite a second spring seat, and a latch recess between the first spring seat and the second spring seat;   a latch assembly comprising a ferrule, the ferrule configured to reciprocate in the latch recess;   a main axle mounted in the respective axle mountings;   an inner arm pivotably mounted to the main axle, the inner arm comprising:
 an inner bearing axle comprising portions extending through the inner arm; 
 an inner bearing rotatably mounted to the inner bearing axle, the inner bearing configured to transfer forces from a cam lobe to the inner arm; and 
 a catch on the inner arm, the catch configured to latch against the ferrule when the ferrule is in a first position, the catch configured to pivot past the ferrule when the ferrule is in a second position; and 
   a first spring mounted to the first spring seat and a second spring mounted to the second spring seat, wherein the first spring and the second spring are biased between the bridge portion and the portions of the inner bearing axle extending through the inner arm,   wherein the inner bearing axle is between the bridge portion and the axle mounting.   
     
     
         2 . The switching roller finger follower of  claim 1 , wherein each arm of the pair of outer arms further comprises:
 a wall portion comprising a projection, an axle mounting, and a bearing axle opening; and   a slider pad extending perpendicular to the wall portion, the slider pad configured to transfer forces from a cam lobe to the respective outer arm.   
     
     
         3 . The switching roller finger follower of  claim 1 , wherein each arm of the pair of outer arms comprises an outer rotatable bearing. 
     
     
         4 . The switching roller finger follower of  claim 1 , wherein the latch assembly further comprises a hydraulic fluid port, the ferrule in fluid communication with the hydraulic fluid port. 
     
     
         5 . The switching roller finger follower of  claim 4 , wherein the ferrule further comprises a fluid recess. 
     
     
         6 . The switching roller finger follower of  claim 1 , wherein the ferrule is configured to reciprocate in the latch recess in response to hydraulic fluid pressure. 
     
     
         7 . (canceled) 
     
     
         8 . (canceled) 
     
     
         9 . The switching roller finger follower of  claim 1 , wherein each respective slider pad is in the shape of an arcuate tab, and each respective slider pad extends like a shelf from an upper edge of the outer arm. 
     
     
         10 . The switching roller finger follower of  claim 1 , wherein each arm of the pair of outer arms comprise a bearing axle opening, and wherein the bearing axle reciprocates in the bearing axle openings when the inner arm pivots on the main axle. 
     
     
         11 . (canceled) 
     
     
         12 . A variable valve lift assembly, comprising the switching roller finger follower of  claim 1 , and further comprising:
 a valve coupling mounted to the main axle;   a valve stem mounted to the valve coupling;   a pair of normal lift cam lobes aligned to transfer forces to respective outer arms; and   a high lift cam lobe comprising a larger diameter portion than the normal lift cam lobes, the high lift cam lobe positioned between the pair of normal lift cam lobes and further configured to transfer forces to the bearing,   wherein the normal lift cam lobes and the high lift cam lobe are eccentric lobes mounted to a cam rail for rotation against the switching roller finger follower.   
     
     
         13 . The variable lift valve assembly of  claim 12 , wherein:
 when the latch assembly is in a latched condition, the catch on the inner arm is latched against the ferrule, the ferrule is in the first position, and the high lift cam lobe pushes the switching roller finger follower a first distance; and   when the latch assembly in in an unlatched condition, the ferrule is unlatched from the catch, the ferrule is in the second position, the high lift cam lobe pushes the bearing to pivot the catch past the lip, and the normal lift cam lobes push on respective outer arms to move the switching roller finger follower a second distance; and   the second distance is less than the first distance.   
     
     
         14 . The variable lift valve assembly of  claim 12 , wherein:
 when the latch assembly is in a latched condition, the catch on the inner arm is latched against the ferrule, the ferrule is in the first position, and the high lift cam lobe pushes the switching roller finger follower a first duration; and   when the latch assembly in in an unlatched condition, the ferrule is unlatched from the catch, the ferrule is in the second position, the high lift cam lobe pushes the bearing to pivot the catch past the lip, and the normal lift cam lobes push on respective outer arms to move the switching roller finger follower a second duration; and   the second duration is less than the first duration.   
     
     
         15 . The variable lift valve assembly of  claim 12 , wherein the latch assembly further comprises a hydraulic fluid port, and the ferrule is in fluid communication with the hydraulic fluid port, and wherein the assembly further comprises a hydraulic lash adjuster mounted in fluid communication with the hydraulic fluid port. 
     
     
         16 . The variable valve lift assembly of  claim 12 , wherein the ferrule is configured to reciprocate within the latch recess within one revolution of the cam rail to switch the switching roller finger follower between a normal lift valve profile and a high lift valve profile. 
     
     
         17 . A method of actuating the switching roller finger follower of  claim 1 , comprising:
 aligning a pair of normal lift cam lobes to selectively transfer forces to respective outer arms; and   aligning a high lift cam lobe to transfer forces to the bearing, the high lift cam lobe comprising a larger diameter portion than the normal lift cam lobes, the high lift cam lobe positioned between the pair of normal lift cam lobes;   rotating the normal lift cam lobes and the high lift cam lobe on a cam rail, wherein the high lift cam lobe is configured to push the bearing more than the normal lift cam lobes push the respective outer arms.   
     
     
         18 . The method of  claim 17 , further comprising:
 reciprocating the ferrule in the latch recess, wherein:
 when the latch assembly is in a latched condition, the catch on the inner arm is latched against the ferrule, the ferrule is in the first position, the normal lift cam lobes do not contact the outer arms, and the high lift cam lobe pushes the bearing of the switching roller finger follower; and 
 when the latch assembly is in an unlatched condition, the ferrule is unlatched from the catch, the ferrule is in the second position, the high lift cam lobe pushes the bearing to pivot the catch past the lip, and the normal lift cam lobes push on respective outer arms to move the switching roller finger follower less than the high lift cam lobe; and 
   performing a late intake valve closing event when the latch assembly is in a latched condition.   
     
     
         19 . (canceled) 
     
     
         20 . (canceled) 
     
     
         21 . (canceled) 
     
     
         22 . (canceled) 
     
     
         23 . (canceled) 
     
     
         24 . (canceled) 
     
     
         25 . (canceled) 
     
     
         26 . The switching roller finger follower of  claim 1 , wherein each arm of the pair of outer arms comprises:
 a first wall portion comprising a first bearing axle opening;   a second wall portion comprising a second bearing axle opening;   an outer bearing axle mounted across the first bearing axle opening and the second bearing axle opening; and   an outer bearing mounted on the outer bearing axle configured to transfer forces from a cam lobe to the respective outer arm.   
     
     
         27 . The switching roller finger follower of  claim 26 , wherein the inner bearing axle protrudes into the second wall portion of each arm of the pair of outer arms. 
     
     
         28 . The switching roller finger follower of  claim 26 , wherein each second wall portion includes a guide recess to receive and guide the inner bearing axle. 
     
     
         29 . The switching roller finger follower of  claim 26 , wherein the inner bearing axle extends into a plane of each second wall portion.