Abstract:
The finger follower employs two independent lost motion arms and a rod which moves longitudinally to lock both arms. The rod is transversely mounted in the follower. In order to avoid premature locking, a clip is employed with tabs that interact with end surfaces of the arms so as to prevent premature movement of the rod from an unlocked position to a locked position.

Description:
This application claims the priority of 61/265,453 filed Dec. 1, 2009, which is incorporated by reference herein. 
    
    
     FIELD OF INVENTION 
     This Invention relates to internal combustion engines and more particularly to switchable roller finger followers used in overhead cam engines where the finger followers can be deactivated in order to deactivate an intake and/or exhaust valve, or to switch between two different lift profiles, a high lift and a low lift profile. 
     BACKGROUND OF INVENTION 
     Switchable roller finger followers are known, see, for example, U.S. Pat. No. 7,174,869. Such finger followers have an outer lever pivotably mounted outside an inner lever and a roller rotatably mounted in a slot in the inner liner. The top surface of the outer lever acts as a contact surface for a high lift cam and the top surface of the roller acts as a contact surface for a low lift cam. A coupling element is mounted at one end of the finger and oil from an oil source is used to activate the coupling element. When the coupling element is activated, it locks the outer lever to the inner lever and requires the follower to follow both the high lift cam and the low lift cam. When the coupling element is deactivated, the outer lever is free to pivot and, under the aid of a spring, the outer lever pivots freely in conjunction with the high lift cam. This movement by the outer lever is conventionally referred to as the lost motion stroke. 
     Conventionally, the outer lever is a unitary structure such that the coupling element need only operate as one part of the outer lever. Typically, the coupling device operated on a yoke portion of the outer layer, the yoke portion being transverse to the longitudinal axis of the finger follower. 
     SUMMARY OF INVENTION 
     The Invention is directed to a finger follower where the outer lever is designed as two separate outer arms, which are not joined by a transverse yoke and which can freely move independent of one another and a coupling element that operates on both arms simultaneously to simultaneously lock both arms. 
     Also, the Invention provides a coupling element that can be activated at any point during the pivotal movement of the arms, at any point during the lost motion stroke, but that locks the arms only when the arms are in a base position. 
     The Invention can be defined as, in a switchable finger follower of the type having two separate outer arms pivotally mounted at one end of an inner lever, a roller rotatably mounted in a slot in the inner lever, the outer arms extending longitudinally towards the other end of the inner lever and a coupling element mounted in the other end of the inner lever, wherein 
     the coupling element has a rod extending laterally from each side wall of the inner lever and the rod is longitudinally movable into and out of engagement with a locking surface of the arms, to lock and unlock the arms in a base position. 
     In order to lock the arms only when the arms are in the base position, a clip is mounted on the rod and movable with the rod, the clip has two tabs, one of each of the tabs opposing a lateral end surface of one of each of the arms when the arms are in the down position thereby preventing the rod from moving into engagement with the top surface of the arms when the arms are in the down position. 
     Broadly, the Invention can be defined as follows: 
     A switchable finger follower for a valve train of an internal combustion engine, comprising: 
     a longitudinally extending, inner lever having a bottom wall with a valve stem support at one end of the lever and a lash adjuster contact surface at the other end of the lever and a slot extending through the lever from the bottom wall to a top wall of the lever; 
     a roller mounted in the slot; 
     two separate, longitudinally extending outer arms, one end of each of the arms pivotally mounted at the one end of the lever, one of each of the arms mounted along one longitudinal sidewall of the lever and the other end of each of the arms extending towards the other end of the lever, each of the arms moving between the down position and a base position; 
     a restoring spring means for restoring the arms to the base position; and 
     a coupling element mounted in a lateral end wall at the other end of the lever, the coupling element having a rod extending laterally from each longitudinal sidewall of the inner lever, the rod longitudinally movable into and out of engagement with a locking surface at the other end of the arms to lock and unlock the arms in the base position. 
     To avoid the rod from longitudinally moving into engagement with the top surface of the arms, a clip is mounted on the rod and movable with the rod, the clip has two tabs, one of each of the tabs opposing a lateral end surface of one of each of the arms when the arms are in the down position thereby preventing the rod from moving into engagement with the arms when the arms are in the down position. 
     Preferably, the coupling element comprises: 
     a longitudinal extending blind bore extending from a lateral end wall at the other end of the lever into the lever; 
     a transverse, oblong hole extending from one longitudinal sidewall to the other longitudinal sidewall of the lever, the oblong hole transversely bisecting the blind bore; 
     the rod mounted in the oblong hole to transverse the blind bore; 
     a spring mounted in the blind bore at the blind end; 
     a longitudinally movable piston mounted in the blind bore on top of the spring, the piston, engaged with the rod and longitudinally movable therewith; and 
     an end cap closing the blind bore and forming an oil chamber between the end cap and the piston for receiving fluid pressure from a lash adjuster, such that the fluid pressure forces the piston into the blind bore which longitudinally moves the rod into engagement with the other end of the arms. 
     Preferably, the clip is a U shaped sheet metal piece where the bottom of the U laterally spans the top wall of the lever and each leg of the U extends downward along the sidewalls of the lever, each leg of the U engages the rod to mount the clip on the rod, one of each of the tabs is formed on each leg of the U at a bottom of the leg of the U, the tab extending transversely to a longitudinal axis of the lever. 
     Preferably, the rod has two circumferential grooves, one of each of the grooves located adjacent the longitudinal sidewalls of the lever and the clip has two C-shaped sections, one of each of the sections engages one of each of the grooves to mount the clip on the rod. 
     Preferably, the restoring spring means is two restoring springs which are each a torsion spring, each spring is mounted on a post extending transversely outward from the longitudinal sidewall, and each spring has a long leg which abuts the arm and a short leg that abuts a stop, the stop is affixed to the lever. 
     These and other aspects of the Invention may be more readily understood by reference to one or more of the following drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-1D  illustrate the follower in an un-locked position; 
         FIGS. 2A-2D  illustrate the follower in a locked position; 
         FIGS. 3A-3D  illustrate the follower wherein the clip is preventing the locking element from locking the outer arms in the locked position; 
         FIG. 4  illustrates an exploded view of the follower; 
         FIG. 5A-5F  illustrates the clip of the Invention; 
         FIG. 6A-6H  illustrate the clip with an oil spray guide and the follower with the clip with the oil spray guide; and 
         FIGS. 7A-7H  illustrates the clip with a throttling function and the follower with the clip with the throttling function. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Turning to  FIGS. 1A-1D ,  FIG. 1A  is a side view of switchable finger follower  10 . Switchable finger follower  10  has inner lever  12  in which roller  14  is housed. Outer arms  16  are pivotably mounted on inner lever  12 . Torsion springs  18  acts on outer arms  16  to restore outer arms  16  to a base position. The base position of outer arms  16  are shown in  FIGS. 2A-2D . Coupling element  20  when activated locks outer arms  16  into the base position as shown in  FIGS. 2A-2D . Clip  22  blocks the movement of coupling element  20  from locking arms  16  until arms  16  are in the base position. 
     Lever  12  has valve stem end  24  with valve stem support  26  thereon. Valve stem support  26  contacts and supports valve stem  27 . Lash adjuster end  28  of lever  12  has contact surface  30  for lash adjuster  31 . 
     Each outer arm  16  is pivotable on lever  12  by means of rod  32 . Each arm  16  has cam contact surface  34  and locking surface  36 . Locking surface  36  is on a bottom surface of arm  16  and interacts with coupling element  20  to lock arms  16  into the base position. 
     Roller  14  has cam contact surface  38 . As will be understood, finger follower  10  is intended for use with an overhead cam engine wherein cam contact surface  34 , and cam contact surface  38  interact with an overhead cam, not shown, so as to effect movement of the valve connected to valve stem  27 . 
     Coupling element  20  has rod  40  which can move longitudinally in oblong hole  42 . The movement of rod  40  is activated through oil pressure supplied by lash adjuster  31  through an inlet in contact surface  30 . To deactivate coupling element  20 , the supply of oil is stopped from lash adjuster  31  and oil can escape from coupling element  20  through outlet  43 . 
       FIGS. 1A through 1D  illustrate switchable finger follower  10  in a deactivated or unlocked mode.  FIG. 1A  is a side view of switchable finger follower  10 ,  FIG. 1B  is a perspective view of finger follower  1 B from the lash adjuster end of the finger follower  10 .  FIG. 1C  is a top view of switchable finger follower  10  and  FIG. 1D  is a perspective view of finger follower  10  from valve stem end of finger follower  10 . 
       FIGS. 2A-2D  illustrate switchable finger follower  10  in the locked mode wherein rod  40  has moved longitudinally towards valve stem end  24  of finger follower  10  and rod  40  has contacted locking surface  36  of each arm  16 . As shown in  FIGS. 2A-2D , arms  16  are in the base position and are locked to move with inner lever  12 . In  FIGS. 1A-1D , arms  16  are not locked and thus move independent of inner lever  12 . 
     Arms  16  are acted on by torsion spring  18  which has long leg  44  and coils  46  and short leg  48 . Long leg  44  acts on contact surface  50  of arms  16 . Torsion spring  18  is mounted on posts  52  of inner lever  12  and short leg  48  abuts stops  54  which are part of inner lever  12 . 
       FIG. 2A  is a side view of finger follower  10  in the locked mode,  FIG. 2B  is a perspective view of finger follower  10  from lash adjuster end  28  in the locked mode;  FIG. 2C  is a top view of lash adjuster  10  in the lock mode and  FIG. 2D  is a perspective view of finger follower  10  in the lock mode from valve stem end  24 . 
       FIGS. 3A-3D  illustrate switchable finger follower  10  wherein clip  22  is shown with tab  56  abutting lateral end surface  58  of outer arms  16 . Tab  56  is spaced away from lateral end surface  58  in  FIGS. 1A-1D  because rod  32  is positioned toward lash adjuster end  28  of lever  12  and arms  16  freely pivot on rod  32 . When coupling element  20  proceeds to move into locked position as illustrated in  FIGS. 2A-2D , rod  40  moves in oblong hole  42  towards valve stem end  24  of lever  12 . When arm  16  is not in the base position as shown in  FIGS. 2A-2D , tab  56  has moved forward and makes contact with lateral end surface  58 . This contact between tab  56  and end surface  58  prevents rod  40  from advancing until such time as arm  16  is in the base position as illustrated in  FIGS. 2A-2D . This provides for proper locking of arms  16  and prevents improper operation of coupling element  20 . As can be seen, spring  18  moves arms  16  and end surface  58  past tabs  56  as arm  16  moves upward. Once end surface  58  has cleared tab  56 , rod  40  is free to move longitudinally towards valve stem end  24  and rod  40  will then contact locking surface  36  to lock arm  16  into the base position as illustrated in  FIGS. 2A-2B . 
       FIG. 3A  illustrates a side view of switchable finger follower  10  wherein tab  56  abuts end surface  58 .  FIG. 3B  is a perspective view of finger follower  10  from the lash adjuster end.  FIG. 3C  is a top view of finger follower  10  and  FIG. 3D  is a perspective view of follower  10  from the valve stem end. In each  FIGS. 3A-3D , tab  56  is abutting end surface  58 . 
       FIG. 4  is an exploded view of finger follower  10 . Shown in  FIG. 4 , coupling element  20  has blind bore  60  which extends longitudinally in lash adjuster end  28  of lever  12 . As can be seen, oblong hole  42  transversely bisects blind bore  60 . Additionally, outlet  43  bisects blind bore  60 . Inside blind bore  60  is mounted coil spring  62  and piston  64 . Piston  64  has cut out  66  for engagement with rod  40  when rod  40  is positioned in oblong hole  42 . End cap  68  closes opening  70  of blind bore  60  and forms oil chamber  71  between the inside wall of end cap  68  and the end wall of piston  64  for receiving oil pressure from lash adjuster  31 . Oil pressure is provided from lash adjuster  31  through an inlet in the lash adjuster contact surface  30  to oil chamber  71  to move piston  64  longitudinally in blind bore  60  and thereby move rod  40  in oblong hole  42 . When oil pressure is released, coil spring  62  moves rod  40  towards lash adjuster end  28  of lever  12 . This movement by coil spring  62  forces oil out of blind bore  60  through outlet  43 . The control and supplying of oil through lash adjuster  31  in order to control the movement of rod  40  and the overall locking and unlocking of coupling element  20  is done in conventional manner using conventional equipment. 
     Rod  40  has circumferential grooves  72 . Circumferential grooves  72  are designed to interact with C-shaped sections  74  of tab  22 . C-sections  74  fit into circumferential grove  72  such that clip  22  moves with rod  40  as rod  40  moves back and forth in oblong hole  42 . 
       FIGS. 5A through 5F  illustrate clip  22  in more detail.  FIG. 5A  is a perspective view of clip  22  shown from the bottom while  FIG. 5B  is a perspective top view of clip  22 .  FIG. 5C  is the bottom view of clip  22 ,  FIG. 5D  is a side view of clip  22 .  FIG. 5E  is a top view of clip  22  and  FIG. 5F  is a front view. As can be seen in  FIGS. 5A-5F , clip  22  is suitably made of sheet metal and has an overall U-shaped configuration with the bottom of U-shaped clip  22  designed to slide along the top wall of lever  12 . Each leg  76  of clip  22  has C-shaped sections  74  for interacting with groove  72  of rod  40 . Tabs  56  are formed at the bottom of leg  76  and have been bent outward at approximately a 90° angle from leg  76 . 
       FIGS. 6A-6H  illustrates an alternative embodiment of a clip of the present Invention. Specifically, clip  80  is illustrated in  FIGS. 6A-6H  wherein clip  80  has oil spray guide  82 .  FIG. 6A  is a bottom perspective view of clip  80 ,  FIG. 6B  is a top perspective view of clip  80 ,  FIG. 6C  is a bottom view of clip  80 ,  FIG. 6D  is a side view of clip  80 ,  FIG. 6E  is a top view of clip  80 ,  FIG. 6F  is a front view of clip  80 ,  FIG. 6G  is a perspective view of switchable finger follower  10  having clip  80  mounted thereon wherein switchable finger follower  10  is in a locked position and is a perspective view taken from lash adjuster end  24 .  FIG. 6H  is a perspective view of finger follower  10  with clip  80  taken from valve stem end  24 . As can be seen in  FIGS. 6G and 6H , oil which is expelled through outlet  43  contacts oil spray guide  82  and is directed towards roller  14 . 
       FIGS. 7A through 7H  illustrate another alternative embodiment of the clip of the present Invention. Specifically, clip  84  having throttle element  86 .  FIG. 7A  is a perspective bottom view of clip  84  with throttle element  86 ,  FIG. 7B  is a top perspective view of clip  84  with throttle element  86 ,  FIG. 7C  is a bottom view of clip  84 ,  FIG. 7D  is a side view of clip  84 ,  FIG. 7E  is a top view of clip  84 ,  FIG. 7F  is a front view of clip  84 ,  FIG. 7G and 7H  are perspective views of switchable finger follower  10  with clip  84  mounted thereon. Perspective views  7 G and  7 H of finger follower  10  illustrate the finger follower in a locked mode. As can be seen, when finger follower  10  moves from a locked mode to the unlocked mode, throttle element  86  moves over outlet  43  to throttle the outlet of oil coming from blind bore  60 . 
     As will be appreciated by those of skill in the art, when the signal is given to couple arms  16  with inner lever  12 , the signal is given independent of the actual location of arms  16 . Tabs  56  in conjunction with end surface  58  provide that the arms are not locked in the partial or full lost motion stroke until such time as the arms are in the base position. 
     Clip  22 ,  80  and  84  are suitably made of stamped and heat treated sheet metal. 
     Reference Characters 
     
         
           10  Switchable finger follower 
           12  inner lever 
           14  roller 
           16  outer arms 
           18  torsion springs 
           20  coupling element 
           22  clip 
           24  valve stem end of lever 
           26  valve stem support 
           27  valve stem 
           28  lash adjuster end of lever 
           30  contact surface lash adjuster 
           31  lash adjuster 
           32  rod 
           34  cam contact surface of arms 
           36  locking surface 
           38  cam contact surface of roller 
           40  rod 
           42  oblong hole 
           43  outlet 
           44  long leg 
           46  coil 
           48  short leg 
           50  contact surface 
           52  post 
           54  stop 
           56  tabs 
           58  lateral end surface 
           60  blind bore 
           62  coil spring 
           64  piston 
           66  cut out 
           68  end cap 
           70  opening 
           71  oil chamber 
           72  circumferential grooves 
           74  C-shaped sections 
           76  leg
 
Reference Characters (Continued)
 
           80  clip 
           82  oil spray guide 
           84  clip 
           86  throttle element