Patent Document

CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation of U.S. application Ser. No. 10/422,308, which was filed on Apr. 24, 2003. 
     
    
     TECHNICAL FIELD  
       [0002]     The present invention relates to hydraulic valve lifters for use with internal combustion engines, more particularly, to an anti-rotation guide which prevents rotation of a deactivation hydraulic valve lifter in a push-rod internal combustion engine, and even more particularly, to an anti rotation guide that minimizes frictional loss between the guide and the lifter body of a deactivation hydraulic valve lifter.  
       BACKGROUND OF THE INVENTION  
       [0003]     Cylinder deactivation during at least a portion of the combustion process is a proven method by which fuel economy can be improved. With fewer cylinders performing combustion, fuel efficiency is increased and the amount of pollutants emitted from the engine is reduced. A known method of providing cylinder deactivation in a push rod engine is by using a deactivation mechanism in the hydraulic valve lifter.  
         [0004]     A hydraulic valve lifter, whether of the deactivating or non-deactivating type, slides reciprocally in an engine bore. The lifter engages a camshaft lobe via a camshaft follower which typically is a roller follower. Unless suitably guided by an anti-rotation mechanism, the lifter may rotate in its bore during reciprocation, thereby undesirably misaligning its follower from the associated cam lobe.  
         [0005]     One version of a prior art anti-rotation guide that prevents rotation of a standard (non-deactivation) hydraulic roller lifter is in the form of a flat plate having apertures for receiving the lifter bodies. The apertures are sized to freely permit reciprocation of the lifter in the guide plate and include a flatted portion along each aperture periphery to matingly engage a flatted portion on each lifter body to prevent the lifter from rotating during reciprocation. In the flat plate version, each lifter must first be individually inserted into its respective engine bore. Then, the plate is positioned on the engine, each guide plate aperture receiving a lifter in its proper rotational orientation. Lastly, the plate is rigidly secured to the engine thereby preventing the lifters from rotating during engine operation.  
         [0006]     Another version of a prior art anti-rotation guide used to keep the follower of a standard hydraulic lifter in alignment with the cam lobe is disclosed in U.S. Pat. No. 5,088,455. In that version, the guide is used to also “kit” a bank of lifters prior to engine assembly by snuggly gripping a portion of the lifter body via a substantial interference fit across flatted segments of the lifter body. Because the guide snuggly grips each lifter, a significant frictional drag is created between the lifter and guide which can impede hydraulic recovery of the lifter&#39;s hydraulic plunger assembly after being drained of oil during shutdown. In some non-deactivation lifters, frictional drag from the interference fit of a gripping guide can be readily compensated for by increasing the size and internal spring force of the hydraulic plunger assembly. However, because of size constraints placed on the deactivation lifter design, this remedy cannot be readily applied to a deactivation lifter assembly.  
         [0007]     In addition, deactivation lifters, as known in the prior art, require a specific rotational orientation to mate with a deactivation oil passage in the engine. A single flat on the lifter body for mating with a corresponding flat on the guide would assure proper alignment with the engine oil passage. However, with only a single flat, some amount of anti-rotation protection is lost. Greater anti-rotation protection could be provided via two opposing flats, but this would defeat the orientation preference needed by deactivation lifters as conferred by a single flat.  
         [0008]     Finally, anti-rotation guides known in the art, and used with standard hydraulic lifters, are closed-ended, providing only a clearance orifice for the associated push rod to reciprocate through the guide. Such a guide cannot accommodate a deactivation hydraulic lifter having an external spring tower which is substantially greater in diameter than the push rod.  
         [0009]     Therefore, what is needed in the art is an anti-rotation guide which accommodates a deactivation lifter and prevents the hydraulic lifter from rotating in its bore during reciprocation.  
         [0010]     What is further needed in the art is an anti-rotation guide which minimizes friction and binding between the guide and the deactivation lifter while also retaining the lifter for kitting purposes.  
       SUMMARY OF THE INVENTION  
       [0011]     The present invention provides an anti-rotation guide for a deactivation hydraulic valve lifter.  
         [0012]     A guide in accordance with the invention is a funnel-shaped element having walls tapering from a larger opening to a smaller opening accommodating of a deactivation hydraulic valve lifter. The smaller opening is sized such that an end of the lifter, which on a deactivation lifter includes the spring tower, may be inserted through the opening and into the guide. The shape of the element permits articulation of a pushrod engaged with the lifter. The guide is fixedly securable to the engine such that the lifter is reciprocable within the guide.  
         [0013]     The smaller opening of the guide is provided with guide keepers having two flats for mating with corresponding flats on the lifter to prevent rotation of the lifter. In the present invention, the keepers serve to engage an outer ridge portion on the lifter and thereby loosely hold the lifters in place in the guide (“kitting”) during engine assembly. The guide flats are preferably formed in an hourglass shape to permit a degree of angular movement of the lifter relative to the guide to prevent binding during reciprocation. Further, a groove is provided in the guide opening or lifter for receiving a longitudinal rib on the mating part to prevent the lifter from being inserted into the guide 180° from the correct orientation. Preferably, the mating walls of the groove and rib of the present invention are formed perpendicular to the flats on the lifter to provide greater resistance to lifter rotation during engine operation.  
         [0014]     Further, ramped flutes disposed longitudinally along the inner walls of the guide opening are provided to center the pushrod into the lifter during assembly. The inside diameter of the lost motion spring tower is stepped as well to aid in centering of the pushrod and to provide operational clearance to the pushrod.  
         [0015]     In a currently-preferred embodiment, anti-rotation guides are provided in guide elements comprising four guides for four valves, two intake and two exhaust, for economy of manufacture and installation. Each of the guides are preferably equipped with a lifter in a pre-assembled kit which then is inserted directly into the engine during assembly thereof, the correct rotational orientation of the lifters and lifter position relative to respective cylinders thus being assured.  
         [0016]     An advantage of the present invention is that the anti-rotation retains the lifter prior to engine installation.  
         [0017]     A further advantage of the present invention is that, once installed, the anti-rotation guide tightly constrains the deactivation lifter rotationally but loosely constrains the lifter axially such that minimal frictional resistance is encountered during axial actuation of the lifter.  
         [0018]     Yet another advantage of the present invention is that a means is provided in the anti-rotation guide to permit a degree of angular movement of the lifter relative to the guide. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]     These and other features and advantages of the invention will be more fully understood and appreciated from the following description of certain exemplary embodiments of the invention taken together with the accompanying drawings, in which:  
         [0020]      FIG. 1  is a partially sectioned, perspective view of a deactivation roller hydraulic valve lifter used in conjunction with an anti-rotation guide in accordance with the present invention;  
         [0021]      FIG. 2A  is an axially-sectioned view of the lifter body of  FIG. 1 ;  
         [0022]      FIG. 2B  is an axially-sectioned view of the lifter body of  FIG. 1  rotated by 90 degrees;  
         [0023]      FIG. 3  is an axially-sectioned view of  FIG. 1 ;  
         [0024]      FIG. 4  is an axially-sectioned view of the pin housing, plunger assembly, and push rod seat of  FIG. 1 ;  
         [0025]      FIG. 5  is an axially-sectioned view of an anti-rotation guide and deactivation roller hydraulic valve lifter in accordance with the present invention;  
         [0026]      FIG. 6  is a perspective view of a multiple anti-rotation guide element assembly in accordance with the invention, shown with two deactivating valve lifters and two standard valve lifters installed in the anti-rotation guide element;  
         [0027]      FIG. 7  is an elevational view of the guide element assembly shown in  FIG. 6 ;  
         [0028]      FIG. 8  is a vertical cross-sectional view of the guide element assembly shown in  FIG. 6 , taken along line  8 - 8  in  FIG. 10 ;  
         [0029]      FIG. 9   a  is a vertical cross-sectional view taken along line  9 - 9  in  FIG. 10 , substantially equivalent to  FIG. 5  showing the lifter on base circle;  
         [0030]      FIG. 9   b  is a vertical cross-sectional view taken along line  9 - 9  in  FIG. 10  showing the lifter at maximum cam lift;  
         [0031]      FIG. 10  is a plan view of the guide element assembly shown in  FIGS. 6 and 7 ;  
         [0032]      FIG. 11  is a cross-sectional view taken along line  11 - 11  in  FIG. 5 ; and  
         [0033]      FIG. 12  is a magnified view of box  12  in  FIG. 5 .  
     
    
       [0034]     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate one preferred embodiment of the invention, in one form, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.  
       DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0035]     Referring to the drawings and particularly to  FIG. 1  herein, a deactivation roller hydraulic valve lifter (DRHVL)  10 , as disclosed in U.S. Pat. No. 6,513,470, includes roller  12 , lifter body  14 , deactivation pin assembly  16 , plunger assembly  18 , pin housing  20 , pushrod seat assembly  22 , spring seat  23 , lost motion spring  24 , and spring tower  26 . As shown, DRHVL  10  is inserted into its respective bore  19  of engine  31  for engagement with the engine camshaft (not shown).  
         [0036]     Roller  12 , associated with body  14  of DRHVL  10 , rides on a lobe of the camshaft and translates the rotary motion of the camshaft to vertical motion of lifter body  14 . An anti-rotation guide (not shown in  FIG. 1 ) secured to the engine fits around the lifter body to prevent the lifter from rotating during reciprocation. Deactivation pin assembly  16  normally engages lifter body  14  and transfers the vertical reciprocation of lifter body  14  to pin housing  20 . Vertical reciprocation is, in turn, transferred to plunger assembly  18  and pushrod seat assembly  22 . Deactivation pin assembly  16  can be selectively disengaged to decouple lifter body  14  from pin housing  20  and to decouple plunger assembly  18  and pin housing  20  from the vertical reciprocation of lifter body  14 .  
         [0037]     Lifter body  14  includes on its outside surface at least one anti-rotation flat  14   a  which is aligned with a similar anti-rotation flat on the interior surface of the anti-rotation guide. Alignment of these flats prevent the lifter from rotating within the guide during reciprocation of the lifter.  
         [0038]     In the anti-rotation guide disclosed in U.S. Pat. No. 5,088,455, the flats on the outside surface of the lifter body are tight fitting to similar flats on the inside surface of the anti-rotation guide so that the guide can snuggly grip the lifter body as a kitted lifter/guide assembly. The assembly relies on the snug grip to keep the lifter in place and in its proper orientation with the cam lobe during engine assembly. With the anti-rotation guides properly positioning and aligning each lifter as a kit, each lifter can be readily inserted into its respective bore  19 .  
         [0039]     Referring now to  FIGS. 2   a  and  2   b , lifter body  14  is an elongate cylindrical member dimensioned to be received within the space occupied by a standard roller hydraulic valve lifter. Lifter body  14  has central axis A and includes cylindrical wall  32  having an inner surface  34 . Inner surface  34  includes circumferential oil supply recess  34   a . Inner surface  34  of cylindrical wall  32  defines annular pin chamber  42 . Pin chamber  42  is a contiguous chamber of a predetermined axial height which extends around the entire circumference of inner surface  34  of cylindrical wall  32 . Control port  38  is defined by an opening that extends through cylindrical wall  32 , terminating at and opening into annular pin chamber  42 . Pressurized oil is injected through control port  38  into annular pin chamber  42  in order to retract deactivation pin assembly  16  from within annular pin chamber  42 . Oil port  40  passes through cylindrical wall  32  and into oil supply recess  34   a , thereby providing a passageway for supplying the hydraulic lash mechanism with oil, as known in the art.  
         [0040]     As best shown in  FIG. 3 , deactivation pin assembly  16  includes preferably two pin members  46 ,  48  interconnected by and biased radially outward relative to lifter body  14  by pin spring  50 . Each of pin members  46 ,  48  are dimensioned to be received within annular pin chamber  42 . A small gap G is provided between stepped flats  46   a ,  48   a  and the lower edge of annular pin chamber  42 . Gap G provides for clearance between flats  46   a  and  48   a  and the lower edge of annular pin chamber  42 , thereby allowing for free movement of pin members  46  and  48  into pin chamber  42 . Each of pin members  46  and  48  define pin bores  52  and  54 , respectively. Each of pin bores  52  and  54  receive a corresponding end of pin spring  50 . In its normal or default position, pin members  46  and  48  of deactivation pin assembly  16  are biased radially outward by pin spring  50  such that at least a portion of each pin member  46  and  48  is disposed within annular pin chamber  42  of lifter body  14 .  
         [0041]     Referring to pin housing  20  and plunger assembly  18  as shown in  FIG. 4 , high pressure chamber  100  is conjunctively defined by bottom inner surface  86  of pin housing  20 , plunger bottom  70  of plunger assembly  18 , and the portion of inner surface  82  of cylindrical side wall  80  of pin housing  20  disposed therebetween. Plunger orifice  74  provides a passageway for the flow of fluid, such as, for example, oil, between high pressure chamber  100  and low pressure chamber  72 . The ball-type check valve formed by plunger ball  62 , plunger spring  64 , and ball retainer  66  selectively controls the ability of the fluid to flow through plunger orifice  74 .  
         [0042]     Spring seat  23 , as best shown in  FIG. 3 , is a ring-shaped member, having collar  130 , flange  132 , and orifice  134 . Collar  130  is disposed concentrically within lifter body  14  and adjacent to the top edge of side wall  80  ( FIG. 4 ) of pin housing  20 . Flange  132  extends radially from collar  130  such that flange  132  overlaps onto the top edge of cylindrical wall  32  of lifter body  14 . The height of gap G is determined by the dimensions of spring seat  23 . More particularly, the length of the axial extension of collar  130  into lifter body  14  determines the axial position of pin housing  20  relative to lifter body  14 , thereby determining the height of gap G.  
         [0043]     Lost motion spring  24  is a coil spring having one end associated with spring seat  23  and the other end associated with spring tower  26 . Lost motion spring  24  has a predetermined installed load which is selected to prevent hydraulic element pump up due to oil pressure in high pressure chamber  100  and due to the force exerted by plunger spring  64 .  
         [0044]     Spring tower  26 , as best shown in  FIG. 3 , is an elongate cylindrical member having an outer wall  140 . A plurality of slots  142  are defined in outer wall  140 . Tabs  144  are formed along the bottom end of outer wall  140 . A portion of outer wall  140  is concentrically disposed within pin housing  20 , adjacent to inner surface  82  of side wall  80 . Slots  142  enable spring tower  26  to be flexible enough to be pushed downward into pin housing  20  until each of tabs  144  are received within and snap into or engage upper annular groove  108  ( FIG. 4 ) formed in side wall  80  of pin housing  20 . Spring tower  26  defines at its top end tower collar  146 , which is associated with the top end of lost motion spring  24 . The lower end of spring tower  26 , disposed within pin housing  20 , acts to limit the extended height of pushrod seat assembly  22 .  
         [0045]     In the deactivated state of DRHVL  10 , as lifter body  14  is vertically displaced by the engine cam lobe, lost motion spring  24  is compressed. As the cam lobe returns to its lowest lift profile, lost motion spring  24  expands and exerts, through spring seat  23 , a downward force on lifter body  14 . Any lift loss that occurs due to leakdown is recovered through the expanding action of plunger spring  64 . Thus, the lash remaining in DRHVL  10  is limited to the gap G which is precisely set through the dimensions of spring seat  23 . Lengthening collar  130  places pin housing  20  axially lower relative to lifter body  14  thereby decreasing the height of gap G. By adjusting the axial dimension of collar  130 , variations in manufacturing tolerances and variations in the dimensions of the component parts of DRHVL  10  can be accurately compensated for while a tight tolerance on gap G is accurately maintained.  
         [0046]     Lost motion spring  24  prevents separation between DRHVL  10  and the engine cam lobe in the deactivated or disengaged state. Further, lost motion spring  24  resists the expansion of DRHVL  10  when the cam is at its lowest lift profile position. The tendency of DRHVL  10  to expand is due to the force exerted by plunger spring  64  and oil pressure within high pressure chamber  100  acting upon plunger  60  of assembly  18 . These forces tend to displace pin housing  20  downward toward roller  12 , thereby reducing gap G. Thus, the oil pressure within high pressure chamber  100  and the force exerted by plunger spring  64  will expand, or pump-up, DRHVL  10  by displacing pin housing  20  downward toward roller  12 . Spring tower  26  is firmly engaged with pin housing  20 . Therefore, any downward movement of or force upon pin housing  20  will be transferred to spring tower  26 . Thus, a compressive force, or a force in a direction toward roller  12 , is exerted upon lost motion spring  24  via the downward force or movement of pin housing  20 . The pre-load or installed load of lost motion spring  24  is selected to resist the tendency of DRHVL  10  to pump-up or expand. If expansion is not resisted or limited by the installed load of lost motion spring  24 , gap G will be reduced as pin housing  20  is displaced downward relative to pin chamber  42 , and may adversely affect the ability of locking pin members  46 ,  48  to engage within pin chamber  42 .  
         [0047]     Referring now to  FIG. 5 , a deactivation roller hydraulic valve lifter and anti-rotation guide assembly  205 , including DRHVL  200  and anti-rotation guide  250  of the present invention, is shown. DRHVL  200  has central axis A 1 , and includes roller  212 , lifter body  214 , deactivation pin assembly  216 , plunger assembly  218 , pin housing  220 , pushrod seat assembly  222 , spring seat  223 , lost motion spring  224 , and spring tower  226 .  
         [0048]     Anti-rotation guide  250  of the present invention has central axis A 2 , and includes generally cylindrical wall  252  surrounding bore  254  having an upper edge  251 , and keepers  256 . Bore  254  defines a first diameter  258  ( FIG. 11 ) as taken at a diameter orientation non-inclusive of keepers  256 . DRHVL  200  is disposed in bore  254  of anti-rotation guide  250 . Spring seat  223 , in accordance with the invention, includes outer ridge portion  232  and inner ring portion  234 . Outer ridge portion  232  is positioned between keepers  256  and upper edge  251 . Inner ring portion  234  is associated with an edge surface of lifter body  214  and pin housing  220 , as shown in  FIG. 5 . Spring seat  223  serves both to set gap G as described above, and, via outer ridge portion  232 , to loosely retain DRHVL  200  in guide  250 , as will be described below.  
         [0049]     The generally cylindrical outer surface of lifter body  214  defines a second diameter  260  and includes recessed areas or flats  214   a ,  214   b , disposed on the end of lifter body  214  opposite roller  212 . First width  262 , measured across keepers  256  engage corresponding flats  214   a , 214   b  in lifter body  214 . Second diameter  260  of lifter body  214  is smaller than first diameter  258  of guide  250 . That is, as shown in  FIG. 11 , after lifter body  214  is inserted into guide  250 , an annular clearance  264  is formed between second diameter  260  and first diameter  258 .  
         [0050]     Second width  266  measured across outer ridge portion  232  of spring seat  223  ( FIG. 5 ) extends slightly beyond a third width  268  of body  214  taken across flats  214   a  and  214   b , such as, for example, by approximately 0.25 mm to approximately 0.75 mm.  
         [0051]     When assembled as shown in  FIG. 5 , DRHVL  200  is inserted from the keeper end of anti-rotation guide  250  and pushed firmly into bore  254  of anti-rotation guide  250 . Since second width  266  measured across outer ridge portion  232  is slightly greater than first width  262  measured across guide keepers  256 , ridge portion  232  deflects keepers  256  until ridge portion  232  is disposed above ledge  270  ( FIG. 12 ) of anti-rotation guide  250  and DRHVL  200  is retained within anti-rotation guide  250 . Thus disposed, the portions of outer ridge portion  232  proximate flats  214   a ,  214   b  extend beyond the outer surface of lifter body  214  and engages or seats upon ledge  270 , thereby retaining DRHVL  200  within anti-rotation guide  250  as a subassembly, (i.e., kitted), for easy installation within engine  31 . Preferably, leading edge  272  and trailing edge  274  of outer ridge portion  232  are radiused to keep ridge portion  232  from biting into keepers  256  when the lifter is inserted into through bore  254 . Spring seat  223  of DRHVL  200  optionally may include upper lip  223   a  around which a first end of lost motion spring  224  is disposed. Upper lip  223   a  prevents excessive radial movement of lost motion spring  224  relative to central axis A 1  during operation of DRHVL  200 .  
         [0052]     While the present invention in  FIG. 5  shows spring seat  223  having a collar portion extending downward toward pin housing  220 , it is understood that seat  223 , does not have to include a collar portion but may be a washer-like, flat member. Moreover, while outer ridge portion  232  is shown as being circular in shape and positioned generally concentric with the lifter body axis, it is understood that ridge portion  232  can be eccentric with the lifter body axis or, rather than being circular in shape, can take the shape of one or more tabs proximate flats  214   a ,  214   b , extending beyond lifter body  214 . Finally, while the present invention is shown as part of a deactivation lifter assembly having a spring tower and an external lost motion spring, it is contemplated that ridge portion  232  could be used in conjunction with a deactivation lifter having an internal lost motion spring or in conjunction with a standard (non-deactivation) lifter.  
         [0053]     It should be particularly noted that using outer ridge portion  232  to retain DRHVL  200  within anti-rotation guide  250  substantially reduces friction between lifter body  214  and anti-rotation guide  250  relative to conventional methods of retaining lifters within anti-rotation guides. Prior art lifters are retained within anti-rotation guides by a substantial interference or frictional fit between the lifter body and the anti-rotation guide. In contrast, in the present invention DRHVL  200  is inserted into anti-rotation guide  250  until outer ridge portion  232  passes keeper portion  256  and seats on ledge  270  of anti-rotation guide  250 . Minimum clearance  264  (or only a slight interference) between the guide and the lifter body permits free reciprocation of the lifter in the guide during engine operation. Thus, the engagement of ledge  270  by outer ridge portion  232  and not an interfering fit between the lifter body and guide retains DRHVL  200  within anti-rotation guide  250 .  
         [0054]     The interface between anti-rotation guide  250  and lifter body  214  imposes substantially no frictional force that counteracts the operation of DRHVL  200  in reciprocating between the valve-closed position ( FIG. 9   a ) and the valve-open position ( FIG. 9   b ), and thus has distinct advantages over the conventional methods of retaining a lifter within an anti-rotation guide as described above. Since the size of the plunger springs used in DRHVLs are limited due to the reduced size of the hydraulic element in such lifters as compared to the size of the hydraulic element in a standard non-deactivation lifter, reducing friction between lifter body  214  and anti-rotation guide  250  enables plunger spring  276  ( FIG. 5 ) to be of a smaller size and of a smaller spring force, while still being of sufficient size/force to provide hydraulic recovery within DRHVL  200 .  
         [0055]     Generally, substantial or complete lifter collapse occurs when engine  31  is not operating, and in lifters that are engaged with or stopped upon a lifting portion of the profile of an associated cam lobe. The valve spring (not shown) of engine  31  pushes through pushrod  259  (shown in phantom in  FIG. 5 ) and displaces plunger assembly  218  axially downward, i.e., in the direction of roller  212 , within and relative to pin housing  220  which, in turn, compresses plunger spring  276  and causes the high pressure chamber to leak down. When engine  31  is first started, and engine oil pressure is relatively low, the only force available to recover leak down and reestablish engagement of pin housing  220 , lifter body  214  and roller  212  with the cam lobe is the force exerted by plunger spring  276 . Any friction between lifter body  214  and anti-rotation guide  250  may be sufficient to counteract the expansion force exerted by plunger spring  276 , and can result in undesirable lifter noise or clatter, especially when the frictional force approaches the force of plunger spring  276 . Since only ledge  270  is engaged by outer ridge portion  232  to retain lifter body  214  within anti-rotation guide  250  in accordance with the invention, substantially no frictional force exists between lifter body  214  and anti-rotation guide  250 . Thus, the force exerted against lifter body  214  by plunger spring  276  is not substantially counteracted by friction between lifter body  214  and anti-rotation guide  250 . Therefore, substantially all of the force of plunger spring  276  is used to bring pin housing  220 , lifter body  214  and roller  212  into engagement with the cam lobe of the engine camshaft. The adverse effects, i.e., lifter noise or clatter, of the constraints imposed upon the size and force of plunger spring  276  are therefore reduced.  
         [0056]     Spring tower  226  of DRHVL  200  includes first portion  226   a  and second portion  226   b . First portion  226   a  is of a smaller diameter relative to second portion  226   b , and thus spring tower  226  has a stepped outside diameter. The increased diameter of second portion  226   b , relative to the smaller diameter of spring tower  26  of DRHVL  10  and relative to the smaller diameter of first portion  226   a , increases the angle through which pushrod  259  can pivot relative to central axis A 1  without contacting second portion  226   b  of spring tower  226  and helps to center the end of the pushrod with the center of socket  219  of pushrod seat assembly  222 . Further, the increased diameter of second portion  226   b  enables the use of larger-diameter lost motion spring  224  having an increased spring force, thereby increasing the engine oil pressure limit under which DRHVL  200  is operable.  
         [0057]     Second portion  226   b  of spring tower  226  also includes opening  225  through which pushrod  259  enters DRHVL  200  for engagement with pushrod seat assembly  222 . A plurality of flutes  282  ( FIG. 5 ) disposed axially about the inner surface of anti-rotation guide  250  serve to centrally guide pushrod  259  toward pushrod seat assembly  222  during engine assembly. Edge surfaces  284  of flutes  282  serve to guide ball end  259   a  of pushrod  259  away from tower collar  246  when the pushrod is inserted into DRHVL  200  through guide  250 .  
         [0058]     Referring to  FIGS. 6 through 8 , guide  250  of the present invention may be conveniently provided in a ganged element  286  wherein a plurality of guides are formed for use with an equal number of lifters. In element  286 , two of the guides  250  are intended for use with DRHVL  200 ; and the other two guides  250 ′ are intended for use with standard, non-deactivating lifters  288 . Thus, the four guides may be conveniently mounted to engine  31  as a unit such as, for example, via a single bolt (not shown) through bolt hole  287 , as known in the art. The four-lifter guide element  286  permits four appropriate lifters to be pre-assembled as a kit  286 ′ and then installed simultaneously into engine  31 .  
         [0059]     Referring again specifically to  FIGS. 5, 11  and  12 , guide  250  is provided with two keepers  256  for engaging two flats  214   a , 214   b  as described above, to provide sufficient torque to resist rotation of the lifter body in its mating guide during engine operation. Each deactivation lifter  200  has an oil port  238  that must mate with a corresponding control oil passage  31   a  in engine  31 , requiring that lifter  200  must be correctly oriented when inserted into its bore  19  in engine  31 ; a single flat  214   a  can provide such orientation, but would provide less torque to resist rotation of the lifter body in its mating guide, as compared to the two-flat design. A second and opposing flat can provide added resistance to lifter rotation, but the addition of a second and opposite flat  214   b  creates ambiguity. In guide  250 , such ambiguity is resolved by providing an indexing rib  290  ( FIG. 11 ) in one of flats  214   b , and a mating longitudinal groove  291  in one of keepers  256  for engagement with rib  290 . Conversely, rib  290  may be provided in one of flats  214   a , 214   b  and grooves  291  may be provided in one of keepers  256 . In the present invention, engagement walls  292  and  293 , of rib  290  and groove  291 , respectively, are formed perpendicular to flats  214   a,b  and parallel to each other, to provide greater resistance to rotation of the lifter body in its mating guide.  
         [0060]     Referring to  FIG. 12 , preferably, the longitudinal edge  294  of keepers  256  is formed in an hourglass shape so that only mid segment  295  of edge  294  is parallel to flats  214   a , 214   b  of body  214 . This shape permits outer ridge portion  232  to engage ledge  270  of ant-rotation guide  250  while in kit  286 ′ form prior to engine installation. Yet, after assembly, relief angle α of first segment  296  and relief angle θ of second segment  297  permit some angular deviation of body  214  from centerline A 2  of anti-rotation guide  250  after kit  286 ′ is installed in engine  31 . Preferably, relief angles α and θ are less than 10°. Preferable, the length of mid segment  295  that is parallel with flats  214   a ,  214   b  is approximately 2.0 mm.  
         [0061]     This application is therefore intended to cover any variations, uses, or adaptations of the present invention using the general principles disclosed herein. Further, this application is intended to cover such departures from the present disclosure as come within the known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

Technology Category: 2