Switching Finger Follower Assembly

Abstract

A finger follower assembly ( 30 ) for variably activating a valve of an internal combustion engine having a camshaft with at least one lobe ( 40 ). The finger follower assembly includes a follower body ( 54 ), a shaft ( 78 ), a cam follower ( 56 ), and a latching mechanism ( 58 ). The cam follower is supported by the shaft and is configured for engagement with the at least one lobe. The cam follower is configured to pilot on the camshaft to maintain an alignment of the cam follower with respect to the at least one lobe. The latching mechanism selectively latches and unlatches the cam follower to the follower body to provide first valve lift capability and a second valve lift capability.

1 . A finger follower assembly for variably activating a valve of an internal combustion engine having a camshaft with at least one lobe, the finger follower assembly comprising:
 a follower body having a first end portion configured to couple to the engine, a second end portion configured to couple to the valve of the engine, and an aperture formed in the follower body between the first and second end portions;   a shaft coupled to the follower body that transverses the aperture;   a cam follower supported at least partially within the aperture by the shaft and configured for engagement with the at least one lobe, the cam follower configured to pilot on the camshaft to maintain an alignment of the cam follower with respect to the at least one lobe; and   a latching mechanism for selectively latching and unlatching the cam follower to the follower body to provide a first valve lift capability and a second valve lift capability.   
     
     
         2 . The finger follower assembly of  claim 1 , wherein the cam follower is movable within the aperture in a direction parallel to a longitudinal axis of the shaft. 
     
     
         3 . The finger follower assembly of  claim 1 , wherein the camshaft includes a central lobe and a lateral lobe adjacent a side of the central lobe, wherein the cam follower is a lateral follower configured to pilot on the central lobe, the finger follower assembly further comprising a central follower configured for engagement with the central lobe. 
     
     
         4 . The finger follower assembly of  claim 3 , wherein the central follower is rotatably supported at least partially within the aperture by the shaft. 
     
     
         5 . The finger follower assembly of  claim 3 , wherein the central follower is coupled with the lateral follower such that movement of the lateral follower with respect to the valve causes movement of the central follower. 
     
     
         6 . The finger follower assembly of  claim 3 , wherein the central lobe includes a perimeter surface that contacts the central follower and a side wall portion that engages the lateral follower to pilot the lateral follower on the camshaft. 
     
     
         7 . The finger follower assembly of  claim 6 , wherein the lateral follower includes a first contact surface configured to engage the lateral lobe and a second contact surface substantially normal to the first contact surface and configured to engage the side wall portion of the central lobe. 
     
     
         8 . The finger follower assembly of  claim 1 , wherein the camshaft includes a first lobe and a second lobe, wherein the first lobe is configured to engage the cam follower, and wherein the cam follower includes a contact surface configured to contact the second lobe to pilot the cam follower. 
     
     
         9 . The finger follower of  claim 1 , wherein the cam follower defines a body portion located at least partially within the aperture, the body portion having a width that is less than a width of the aperture such that the cam follower can move with respect to the follower body in a direction parallel to a longitudinal axis of the shaft. 
     
     
         10 . The finger follower assembly of  claim 1 , wherein the latching mechanism includes a latching member having an engagement surface, the latching member selectively interconnects the cam follower and the follower body, and wherein the cam follower includes an engagement surface that at least partially defines an aperture that receives the latching mechanism, and wherein at least one of the engagement surfaces is at partially convex. 
     
     
         11 . The finger follower assembly of  claim 10 , wherein the engagement surface of the cam follower is at least partially convex. 
     
     
         12 . The finger follower assembly of  claim 1 , wherein the cam follower is integrally formed as a single component. 
     
     
         13 . A finger follower assembly for variably activating a valve of an internal combustion engine, the finger follower assembly comprising:
 a follower body having a first end portion configured to couple to the engine, a second end portion configured to couple to the valve of the engine, and an aperture formed in the first end portion;   a cam follower supported by the follower body; and   a latching mechanism operable to selectively engage and disengage the cam follower to provide a first valve lift capability and a second valve lift capability, the latching mechanism including,
 a base portion, 
 a piston movable relative to the base portion between an extended position and a retracted position, and 
 a biasing member coupled between the base portion and the piston to bias the piston toward the retracted position, and wherein the base portion, the piston, and the biasing member are at least partially located within the aperture. 
   
     
     
         14 . The finger follower assembly of  claim 13 , wherein the biasing member is a tapered spring. 
     
     
         15 . The finger follower assembly of  claim 13 , wherein the aperture has a generally uniform inner dimension. 
     
     
         16 . The finger follower assembly of  claim 15 , wherein the aperture is a cylindrical bore having a generally constant diameter. 
     
     
         17 . The finger follower assembly of  claim 13 , wherein the base portion includes a tang, wherein the piston includes a slot, and wherein the tang is received within the slot of the piston to provide for a limited amount of rotation of the piston with respect to the follower body. 
     
     
         18 . The finger follower assembly of  claim 13 , wherein a portion of the piston is located within the aperture, and wherein the portion of the piston has a generally constant outer dimension. 
     
     
         19 . A finger follower assembly for variably activating a valve of an internal combustion engine, the finger follower assembly comprising:
 a follower body having a first end portion configured to couple to the engine, a second end portion configured to couple to the valve of the engine, and an aperture formed in the first end portion;   a cam follower supported by the follower body; and   a latching mechanism at least partially positioned in the aperture and operable to selectively engage and disengage the cam follower to provide a first valve lift capability and a second valve lift capability, wherein the latching mechanism includes an engagement surface, and wherein the cam follower includes an engagement surface configured to engage the engagement surface of the latching mechanism, and wherein at least one of the engagement surfaces is at least partially convex.   
     
     
         20 . The finger follower assembly of  claim 19 , wherein the engagement surface of the cam follower is at least partially convex. 
     
     
         21 . A finger follower assembly for variably activating a valve of an internal combustion engine, the finger follower assembly comprising:
 a follower body having a first end portion configured to couple to the engine, a second end portion configured to couple to the valve of the engine;   a cam follower supported by the follower body;   a latching mechanism operable to selectively engage and disengage the cam follower to provide a first valve lift capability and a second valve lift capability, the latching mechanism at least partially defining a fluid chamber; and   a vent passageway formed in the first end portion of the follower body and providing selective fluid communication between the fluid chamber and an outer surface of the follower body.   
     
     
         22 . The finger follower assembly of  claim 21 , further comprising a movable member positioned at least partially within the vent passageway to provide selective fluid communication between the fluid chamber and the outer surface of the follower body. 
     
     
         23 . The finger follower assembly of  claim 22 , wherein the fluid chamber communicates with a source of pressurized fluid, and wherein the movable member is movable in response to variations in a pressure of the source of pressurized fluid. 
     
     
         24 . The finger follower assembly of  claim 23 , wherein the movable member is a piston positioned within a secondary passageway, the secondary passageway in fluid communication with the vent passageway. 
     
     
         25 . The finger follower assembly of  claim 24 , wherein the secondary passageway is in fluid communication with the source pressurized fluid. 
     
     
         26 . The finger follower assembly of  claim 21 , further comprising a second vent passageway that provides generally constant fluid communication between the fluid chamber and an outer surface of the follower body.