Three arm finger follower with cam switching profile and compression lost motion springs
View Patent ↗A switchable roller finger follower is provided having an inner lever and two separate outer arms mounted at one end to a swing pivot axle that extends through the inner lever. A roller is mounted in the inner lever. The outer arms extend longitudinally along sides of the inner lever and include high lift cam contact surfaces. The inner lever includes a compression spring support extending out from each of the sides. The outer arms each include a corresponding spring support facing the respective spring support of the inner lever. A compression spring is located on each of the sides of the inner lever between the corresponding spring supports. A coupling arrangement is located between the inner lever and the outer arms which in a locked position, locks the outer arms in position on the inner lever, and in an unlocked position, allows the outer arms to pivot.
1. A switchable roller finger follower having a high lift and a low lift mode for a valve train of an internal combustion engine, comprising:
an inner lever having a slot in which a roller is mounted by a transverse axle;
two separate outer arms that extend along longitudinal sides of the inner lever that are mounted for pivoting movement at one end of the inner lever by a swing pivot axle, the two separate outer arms each include a high lift cam contact surface located adjacent to the roller;
the inner lever includes compression spring supports extending out from each of the longitudinal sides toward a respective one of the two separate outer arms, and each of the two separate outer arms includes a corresponding spring support located in a position facing a respective one of the compression spring supports of the inner lever;
a compression spring is located on each of the longitudinal sides of the inner lever between the compression spring supports and the corresponding spring supports on the two separate outer arms; and
a coupling arrangement is located between the inner lever and the two separate outer arms which in a locked position, locks the two separate outer arms to the inner lever at least in an activation direction of a valve, and in an unlocked position, allows the two separate outer arms to pivot relative to the inner lever.
2. The switchable roller finger follower of claim 1 , wherein the two separate outer arms are attached in a rotationally fixed manner to the swing pivot axle so that they pivot together as a unit.
3. The switchable roller finger follower of claim 1 , wherein the two separate outer arms are held with a slip fit on the swing pivot axle and can pivot relative to the swing pivot axle.
4. The switchable roller finger follower of claim 1 , wherein the compression springs are located in line with a cam contact force vector, in line with the transverse axle that supports the roller.
5. The switchable roller finger follower of claim 1 , wherein the coupling arrangement includes hydraulically actuated coupling elements that extend from the inner lever into coupling element receptacles located in each of the two separate outer arms.
6. The switchable roller finger follower of claim 5 , wherein the coupling element receptacles are formed as a slot in each of the two separate outer arms that face a respective one of the longitudinal sides of the inner lever, with a top of each of the slots acting on the coupling elements when the coupling elements are in the locked position in order to transfer a cam lift force.
7. The switchable roller finger follower of claim 5 , wherein the coupling elements are spring biased to an unlocked position.
8. The switchable roller finger follower of claim 5 , wherein the coupling elements are located in a hole in the inner lever having a lip at a first end and being held in the hole by a lock ring that is press fit in the second end of the hole.
9. The switchable roller finger follower of claim 1 , wherein a spring boss is located on each of the compression spring supports of the inner lever and on each of the two separate outer arms, and the compression springs are insertable from the longitudinal sides between the spring bosses on the two separate outer arms and the inner lever which retain the compression springs in position.
10. The switchable roller finger follower of claim 1 , wherein the coupling arrangement includes a clutch element located between the inner lever and the two separate outer arms.