Abstract:
A switching roller finger follower including: a housing including first and second walls; a first secondary arm pivotably connected to the housing and including a first groove; a second secondary arm pivotably connected to the housing and including a second groove; and a roller disposed between the first and second walls and including an axle passing through the walls and having a first end disposed in the first groove and a second end disposed in the second groove. A method of fabricating a switching roller finger follower, including: disposing a roller between first and second walls for a housing; passing an axle through the roller and the walls; pivotably connecting first and second secondary arms to the housing; disposing a first end of the axle in a first groove in the first arm; and disposing a second end of the axle in a second groove in the second arm.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 61/905,527, filed Nov. 18, 2013, which application is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a switching roller finger follower with secondary arms having ends stops formed by grooves in the secondary arms. Respective ends of an axle for a roller bearing in the switching roller finger follower are configured to engage the ends stops to limit rotation of the secondary arms. 
     BACKGROUND 
       FIG. 9  is a perspective view of a protrusion, on housing  300  of a prior art switching roller finger follower, for engaging ends stops on a secondary arm. 
       FIG. 10  is a perspective view of end stops on prior art secondary arm  302 . The following should be viewed in light of  FIGS. 9 and 10 . Transport and overswing ends stops are used in switching roller finger followers to prevent excessive rotation of secondary arms, which can cause damage to the follower, as a result of malfunction of the follower. 
     For example, as is known in the art, a locking pin (not shown) is used to block rotation of the secondary arms during a locked mode. For example, end  304  of arm  302  is arranged to contact the locking pin when force from a cam lobe (not shown) engaged with surface  306  of arm  302  causes arm  302  to rotate in direction RTD 1 . If the locking pin does not displace the proper distance at the proper time (a mis-switch), the force from the cam lobe causes end  304  to slide past the locking pin so that arm  302  continues to rotate in direction RTD 1 . Overswing endstop  308 , formed in arm  302 , is configured to engage protrusion  310  on housing  300  to block further rotation in direction RTD 1 . However, a large rotational force is imparted to arm  302  by the cam lobe and the magnitude of this force can cause endstop  308  to shear protrusion  310  from housing  300  causing further rotation of arm  302 . This further rotation can cause failure of a follower including housing  300  and arm  302 . For example, a lost motion spring (not shown) engaged with arm  302  is used to urge arm  302  in direction RTD 2 , opposite RTD 1 , as described below. If arm  302  is rotated too far in direction RTD 1 , the spring is overstressed, resulting in various failure modes for a switching roller finger follower including housing  300  and arm  302 . 
     After a mis-switch in the locked mode, the locking pin retracts to enable rotation of the secondary arm in direction RTD 2  via a spring (not shown). Rotation of the secondary arm in direction RTD 2  is blocked by contact of transport endstop  312 , formed in secondary arm  302 , with protrusion  310 . The rotation of the secondary arm in direction RTD 1  is opposed by the spring force of the spring. The additional rotation of the secondary arm due to the mis-switch results in an increase in the spring force, which further results in an increase of the force applied by endstop  312  to protrusion  310 . The magnitude of this force can cause endstop  308  to shear protrusion  310  from housing  300  enabling excess rotation of arm  302  in direction RTD 2 , which can cause failure of a follower including housing  300  and arm  302 . 
     SUMMARY 
     According to aspects illustrated herein, there is provided a switching roller finger follower, including: a housing including first and second walls; a first secondary arm pivotably connected to the housing and including a first groove; a second secondary arm pivotably connected to the housing and including a second groove; and a roller disposed between the first and second walls and including a first axle passing through the first and second walls and having a first end disposed in the first groove and a second end disposed in the second groove. 
     According to aspects illustrated herein, there is provided a switching roller finger follower, including: a housing including first and second walls; a first secondary arm pivotably connected to the housing and including a first groove with first and second ends; a second secondary arm pivotably connected to the housing and including a second groove with third and fourth ends; and a roller disposed between the first and second walls and including a first axle passing through the first and second walls and having a first end disposed in the first groove and a second end disposed in the second groove. The first and third ends block pivoting of the first and second secondary arms in a first direction. The second and fourth ends block pivoting of the first and second secondary arms in a second direction opposite the first direction. 
     According to aspects illustrated herein, there is provided a method of fabricating a switching roller finger follower, including: disposing a roller between first and second walls for a housing; passing a first axle through the roller and through first and second through-bores in the first and second walls, respectively; pivotably connecting first and second secondary arms to the housing; disposing a first end of the first axle in a first groove in the first secondary arm; and disposing a second end of the first axle in a second groove in the second secondary arm. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments are disclosed, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, in which: 
         FIG. 1A  is a perspective view of a cylindrical coordinate system demonstrating spatial terminology used in the present application; 
         FIG. 1B  is a perspective view of an object in the cylindrical coordinate system of  FIG. 2A  demonstrating spatial terminology used in the present application; 
         FIG. 2  is a perspective view of a switching roller finger follower with ends stops in secondary arms; 
         FIG. 3  is perspective view of the switching roller finger follower in  FIG. 2  with the secondary arms removed; 
         FIG. 4  is a perspective view of a secondary arm from  FIG. 2  showing a groove; 
         FIG. 5  is a cross-sectional view generally along line  5 / 6 - 5 / 6  in  FIG. 2  with the secondary arms contacting transport end stops; 
         FIG. 6  is a cross-sectional view generally along line  5 / 6 - 5 / 6  in  FIG. 2  with the secondary arms contacting overswing end stops; 
         FIG. 7  is an exploded view of the switching roller finger follower in  FIG. 2  with the secondary arms and roller removed; 
         FIG. 8  is a perspective view of the switching roller finger follower of  FIG. 2  in an unlocked mode and engaged with a valve train; 
         FIG. 9  is a perspective view of a protrusion on a housing of a prior art switching roller finger follower for engaging with ends stops on a secondary arm; and, 
         FIG. 10  is a perspective view of end stops on a prior art secondary arm. 
     
    
    
     DETAILED DESCRIPTION 
     At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical, or functionally similar, structural elements of the disclosure. It is to be understood that the disclosure as claimed is not limited to the disclosed aspects. 
     Furthermore, it is understood that this disclosure is not limited to the particular methodology, materials and modifications described and as such may, of course, vary. It is also understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to limit the scope of the present disclosure. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. It should be understood that any methods, devices or materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure. 
       FIG. 1A  is a perspective view of cylindrical coordinate system  80  demonstrating spatial terminology used in the present application. The present invention is at least partially described within the context of a cylindrical coordinate system. System  80  has a longitudinal axis  81 , used as the reference for the directional and spatial terms that follow. The adjectives “axial,” “radial,” and “circumferential” are with respect to an orientation parallel to axis  81 , radius  82  (which is orthogonal to axis  81 ), and circumference  83 , respectively. The adjectives “axial,” “radial” and “circumferential” also are regarding orientation parallel to respective planes. To clarify the disposition of the various planes, objects  84 ,  85 , and  86  are used. Surface  87  of object  84  forms an axial plane. That is, axis  81  forms a line along the surface. Surface  88  of object  85  forms a radial plane. That is, radius  82  forms a line along the surface. Surface  89  of object  86  forms a circumferential plane. That is, circumference  83  forms a line along the surface. As a further example, axial movement or disposition is parallel to axis  81 , radial movement or disposition is parallel to radius  82 , and circumferential movement or disposition is parallel to circumference  83 . Rotation is with respect to axis  81 . 
     The adverbs “axially,” “radially,” and “circumferentially” are with respect to an orientation parallel to axis  81 , radius  82 , or circumference  83 , respectively. The adverbs “axially,” “radially,” and “circumferentially” also are regarding orientation parallel to respective planes. 
       FIG. 1B  is a perspective view of object  90  in cylindrical coordinate system  80  of  FIG. 1A  demonstrating spatial terminology used in the present application. Cylindrical object  90  is representative of a cylindrical object in a cylindrical coordinate system and is not intended to limit the present invention in any manner. Object  90  includes axial surface  91 , radial surface  92 , and circumferential surface  93 . Surface  91  is part of an axial plane, surface  92  is part of a radial plane, and surface  93  is a circumferential surface. 
       FIG. 2  is a perspective view of switching roller finger follower  100  with ends stops in secondary arms. 
       FIG. 3  is perspective view of switching roller finger follower  100  in  FIG. 2  with secondary arms removed. 
       FIG. 4  is a perspective view of a secondary arm from  FIG. 2  showing a groove. 
       FIG. 5  is a cross-sectional view generally along line  5 / 6 - 5 / 6  in  FIG. 2  with the secondary arms contacting transport end stops. 
       FIG. 6  is a cross-sectional view generally along line  5 / 6 - 5 / 6  in  FIG. 2  with the secondary arms contacting overswing end stops. The following should be viewed in light of  FIGS. 2 through 6 . Switching roller finger follower  100  includes: housing  102  with walls  104  and  106 ; secondary arm  108  pivotably connected to the housing and including groove  110 ; secondary arm  112  pivotably connected to the housing and including groove  114 ; and roller  116 . Roller  116  is disposed between the walls  104  and  106  and includes axle  118  passing through walls  104  and  106 , in particular through through-bores  120  and  122  in walls  104  and  106 , respectively. Axle  118  includes end  124  disposed in groove  110  and end  126  disposed in groove  114 . As further described below, contact between ends  124  and  126  and secondary arms  108  and  112 , respectively, is arranged to limit an extent of rotation of secondary arms  108  and  112  with respect to housing  102 . 
     In an example embodiment, grooves  110  and  114  are formed as indentations in surfaces  128  and  130  of arms  108  and  112 , respectively, that is, the grooves do not pass completely through material forming the secondary arms. In an example embodiment (not shown), grooves  110  and  114  pass completely through material forming the secondary arms. 
     Walls  104  and  106  includes walls surfaces  132  and  134 , respectively, facing each other and roller  116  is disposed between surfaces  132  and  134 . Axle  118  includes longitudinal axis LA 1 , wall  104  includes surface  136  facing in axial direction AD 1  parallel to longitudinal axis LA 1 , and wall  106  includes surface  138  facing in axial direction AD 2 , opposite AD 1 . End  124  of axle  118  extends past surface  136  in direction AD 1  and end  126  of axle  118  extends past surface  138  in direction AD 2 . 
     Switching roller finger follower  100  includes axle  140 , with longitudinal axis LA 2 , passing through walls  104  and  106 . Secondary arms  108  and  112  are engaged with axle  140  as is known in the art and are pivotable about axle  140 . Groove  110  is bounded by transport stop end  142 A and overswing stop end  144 A. Groove  114  is bounded by transport stop end  142 B and overswing stop end  144 B. Rotation of secondary arms  108  and  112  about axle  140  is blocked in rotational direction RTD 1  by contact of ends  124  and  126  with ends  144 A and  144 B. Rotation of secondary arms  108  and  112  about axle  140  is blocked in rotational direction RTD 2 , opposite direction RTD 1 , by contact of ends  124  and  126  with ends  142 A and  144 B. Center line  146  connects ends  142 A and  144 A at fixed distance D 1  from longitudinal axis LA 2 , in direction RD 1  orthogonal to axis LA 2 . The discussion regarding centerline  146  is applicable to groove  114 . 
     Groove  110  is bounded by side walls  148  and  150  at fixed distances D 2  and D 3 , respectfully, from axis LA 2  in a direction RD 1 . Line L 1  orthogonal to axis LA 2  passes through axle  118  and side walls  148  and  150 . The discussion regarding side walls  148  and  150  is applicable to groove  114 . 
       FIG. 7  is an exploded view of switching roller finger follower  100  in  FIG. 2  with the secondary arms and roller removed. The following should be viewed in light of FIGS.  2  through  7 . Switching roller finger follower  100  includes shuttle pin  152  with notch  154  and locking pin  156  passing through the notch. Locking pin  156  passes through slots  158  and  160  in walls  104  and  106 , respectively. Shuttle pin is at least partially disposed in passageway  162  in locking barrel  164 . Seal  166  seals passageway  162 . As is known in the art, in a locked mode for switching roller finger follower  100 , locking pin  156  is positioned to block rotation of secondary arms  108  and  112  about axle  140 . 
       FIG. 8  is a perspective view of switching roller finger follower  100  of  FIG. 2  in an unlocked mode and engaged with valve train  200 . The following should be viewed in light of  FIGS. 2 through 8 . Follower  100  includes contact surface  168  and attachment portion  170  arranged to pivotably connect the housing  102  to a support element. The contact surface is arranged to contact valve stem  202 . In the locked mode, cam lobes  204  and  206  of a cam shaft (not shown) for valve train  200 , including valve stem  202 , are arranged to contact arms  108  and  112 , in particular contact surfaces  172  and  174 , respectively. Since rotation of arms  108  and  112  is blocked by contact with locking pin  156 , the pressure applied by the cam lobes causes the follower to pivot around axis AR for the connection point in direction RTD 3 . Via contact surface  166 , follower  100  pushes the stem in direction DR1, for example, to open a valve including the valve stem. 
     In the unlocked mode, when the cam lobes contact secondary arms  108  and  112 , the arms are free to pivot about axle  140 , for example, in direction RTD 1 . Thus, the contact between the cam lobes and secondary arms  108  and  112  is accommodated by the pivoting such that contact between the cam lobes and secondary arms  108  and  112  does not cause housing  102  to displace with respect to the support element. Therefore, the cam lobes do not cause follower  100  to operate the valve. Springs  176  and  178  urge arms  108  and  112 , respectively, in direction RTD 2  to ensure that arms  108  and  112  are in position for the locking mode. 
     As noted above, excessive rotation of arms  108  and  112  can cause malfunctioning of follower  100 . For example, in a mis-switch of follower  100 , endstops  142 A/B and  144 A/B contact ends  124  and  126  with significant force. Advantageously, axle  118  is extremely robust and provides the desired rotational blockage of arms  108  and  112  without incurring damage. Thus, the use of ends  124  and  126  to engage endstops  142 A/B and  144 A/B ensures that in the event of malfunction of follower  100 , for example, due to a mis-switch, rotation of arms  108  and  112  is limited in a manner enabling follower  100  to recover from the malfunction. 
     It will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.