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.
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 RTD1. 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 RTD1. Overswing endstop 308, formed in arm 302, is configured to engage protrusion 310 on housing 300 to block further rotation in direction RTD1. 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 RTD2, opposite RTD1, as described below. If arm 302 is rotated too far in direction RTD1, 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 RTD2 via a spring (not shown). Rotation of the secondary arm in direction RTD2 is blocked by contact of transport endstop 312, formed in secondary arm 302, with protrusion 310. The rotation of the secondary arm in direction RTD1 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 RTD2, which can cause failure of a follower including housing 300 and arm 302.
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.
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:
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.
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.
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 LA1, wall 104 includes surface 136 facing in axial direction AD1 parallel to longitudinal axis LA1, and wall 106 includes surface 138 facing in axial direction AD2, opposite AD1. End 124 of axle 118 extends past surface 136 in direction AD1 and end 126 of axle 118 extends past surface 138 in direction AD2.
Switching roller finger follower 100 includes axle 140, with longitudinal axis LA2, 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 142A and overswing stop end 144A. Groove 114 is bounded by transport stop end 142B and overswing stop end 144B. Rotation of secondary arms 108 and 112 about axle 140 is blocked in rotational direction RTD1 by contact of ends 124 and 126 with ends 144A and 144B. Rotation of secondary arms 108 and 112 about axle 140 is blocked in rotational direction RTD2, opposite direction RTD1, by contact of ends 124 and 126 with ends 142A and 144B. Center line 146 connects ends 142A and 144A at fixed distance D1 from longitudinal axis LA2, in direction RD1 orthogonal to axis LA2. The discussion regarding centerline 146 is applicable to groove 114.
Groove 110 is bounded by side walls 148 and 150 at fixed distances D2 and D3, respectfully, from axis LA2 in a direction RD1. Line L1 orthogonal to axis LA2 passes through axle 118 and side walls 148 and 150. The discussion regarding side walls 148 and 150 is applicable to groove 114.
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 RTD1. 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 RTD2 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 142A/B and 144A/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 142A/B and 144A/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.
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.
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7174869 | Proschko et al. | Feb 2007 | B2 |
7909007 | Manther et al. | Mar 2011 | B2 |
20080149059 | Murphy | Jun 2008 | A1 |
20110197843 | Manther | Aug 2011 | A1 |
Number | Date | Country | |
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20150135893 A1 | May 2015 | US |
Number | Date | Country | |
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61905527 | Nov 2013 | US |