Patent Publication Number: US-7913656-B2

Title: Variable displacement engine having selectively engageable rocker arm with positioning device

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to an internal combustion engine having a selectively engageable rocker arm with a device for positioning the rocker arm while disengaged. 
     2. Background Art 
     Variable displacement or displacement on demand engines offer the performance of a larger displacement engine with improved fuel economy associated with a smaller displacement engine by selectively activating and deactivating one or more cylinders in response to driver demand and current operating and/or ambient conditions. One strategy used in mechanical valvetrains for selectively deactivating cylinders is to disengage or unlatch at least the intake rocker arms and associated intake valves of selected cylinders. To transition to a higher displacement operating mode, the rocker arms engage or latch to actuate the associated intake valve, which requires alignment of the latching mechanism and the associated rocker arms. Additional mechanical lash or clearance may be added to the system to accommodate manufacturing and assembly tolerances and valvetrain component wear while ensuring proper alignment and latching. Although suitable for some applications, the additional lash added to the system to ensure reliable alignment and latching may result in undesirable noise. 
     Hydraulic lash adjustment mechanisms are used in various types of mechanical valvetrains to compensate for manufacturing and assembly tolerances and component variations due to temperature changes and wear. In variable displacement engine applications having rocker arms that are selectively coupled and uncoupled to activate and deactivate cylinders, movement of the lash adjuster may result in a corresponding change of position of the latching alignment hole. As such, to ensure proper latching across the range of motion of the lash adjuster under varying operating conditions while also accommodating valvetrain design tolerances, the actuating cam profiles are modified for at least the selectively deactivated cylinders, resulting in design compromises with respect to various factors, such as manufacturing cost and complexity, noise, reliability, and durability, for example. 
     SUMMARY 
     Systems and methods for selectively activating and deactivating gas exchange valves in a variable displacement internal combustion engine include a rocker arm having a positioning device that compensates for movement of a lash adjustment device to position the rocker arm within a desired coupling range to facilitate coupling of the rocker arm during activation of an associated engine cylinder. 
     In one embodiment, a multi-cylinder internal combustion engine having at least one cylinder with at least one mechanically operated intake or exhaust valve selectively deactivated during operation in a reduced displacement mode includes a valvetrain having at least one rocker arm with a first end for engaging the selectively deactivated valve and a second end with a lever pivotable relative to the rocker arm to maintain the lash adjuster position and keep the rocker arm within a desired coupling range while the valve is deactivated. The valvetrain is actuated by a camshaft disposed above the intake/exhaust valves in an overhead cam configuration having a plurality of cams including a concentric cam and an adjacent eccentric cam associated with selectively deactivated cylinders. A stationary fulcrum shaft extends through associated rocker arms and provides pressurized oil for lubrication and operation of the hydraulic lash adjuster. A second rocker arm or eccentric cam follower is mounted for rotation about the fulcrum shaft and includes a first end contacting the eccentric cam, a second end contacting a spring, and a coupling hole disposed between the first and second ends. The first rocker arm lever resiliently contacts the concentric cam when decoupled from the second rocker arm or eccentric cam follower such that the coupling hole of the first rocker arm remains within a desired coupling range for coupling to the second rocker arm by movement of a pin through the first and second coupling holes as the coupling hole of the second rocker arm moves past the coupling hole of the first rocker arm during valve activation. 
     The present disclosure also includes a method for operating a multi-cylinder internal combustion engine having at least one cylinder with at least one mechanically operated intake and/or exhaust valve selectively deactivated during operating in a reduced displacement mode. The method includes positioning a rocker arm having a hydraulic lash adjuster within a desired coupling range by opposing movement of the hydraulic lash adjuster while the intake and/or exhaust valve is deactivated and the rocker arm is uncoupled from movement with an eccentric cam. 
     Embodiments of a variable displacement engine and associated rocker arm according to the present disclosure provide various advantages. For example, the spring-loaded positioning device of one embodiment maintains the rocker arm in a desired latching position for coupling with an associated rocker arm or eccentric cam follower during activation of the valve facilitating use of the same cam profiles for cylinders that can be deactivated and those without deactivation capability. Eliminating design compromises associated with ensuring reliable coupling by modification of the cam profiles provides more optimized profiles to improve durability and combustion performance while reducing noise. A resilient follower lever for a rocker arm according to the present disclosure reduces the contact loads reducing wear and improving durability. 
     The above advantages and other advantages and features of the present disclosure will be readily apparent from the following detailed description of the preferred embodiments when taken in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partial cross-sectional view of an internal combustion engine having a valvetrain selectively operable in a reduced displacement mode according to one embodiment of the present disclosure; 
         FIG. 2  illustrates a rocker arm having a positioning device and hydraulic lash adjuster according to one embodiment of the present invention; 
         FIG. 3  is a side view of a valvetrain having an intake valve selectively coupled to an eccentric cam follower to activate a corresponding cylinder of an internal combustion engine according to one embodiment of the present disclosure; 
         FIG. 4  is a perspective view of a valvetrain having a rocker arm with a positioning device according to one embodiment of the present disclosure; 
         FIG. 5  is a perspective view of an alternative embodiment of a rocker arm having a positioning device according to the present disclosure; 
         FIG. 6  is a partial cross-sectional view of the embodiment of  FIG. 5  illustrating an adjustable stop for the positioning device; 
         FIG. 7  is a perspective view of one embodiment for an adjustable positive stop for a positioning device according to the present disclosure; 
         FIG. 8  is a front view of an alternative embodiment for an engine having a valvetrain using rocker arms as shown in the embodiment of  FIG. 5  for selectively deactivating an intake and an exhaust valve; and 
         FIG. 9  is a top view of the embodiment of an engine valvetrain as illustrated in  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
     As those of ordinary skill in the art will understand, various features of the present disclosure as illustrated and described with reference to any one of the Figures may be combined with features illustrated in one or more other Figures to produce embodiments of the present disclosure that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. However, various combinations and modifications of the features consistent with the teachings of the present disclosure may be desired for particular applications or implementations. 
       FIGS. 1-9  illustrate operation of an internal combustion engine and valvetrain according to representative embodiments of the present disclosure. Multiple cylinder internal combustion engine  10  is generally of conventional design with the exception of various valvetrain components as described herein. As such, various conventional features associated with the engine and valvetrain may not be explicitly illustrated or described. Those of ordinary skill in the art will recognize that the present invention may be used in various types and configurations of engines including but not limited to compression ignition and spark ignition engines arranged in a “V” configuration or an in-line configuration, for example. The representative embodiments illustrated include a two-valve-per-cylinder overhead cam engine. However, a valvetrain with rocker arms according to the present disclosure may be used in any applications having at least one mechanically actuated and selectively deactivated gas exchange valve associated with at least one cylinder for operating the engine in a reduced or variable displacement mode. 
     A “cam follower” as used herein refers in the broadest sense to any device that contacts or follows a cam profile on a rotating camshaft to provide a desired position or motion, which may include a reciprocating motion for valve actuation when following an eccentric cam profile, or a substantially stationary position when following a cam profile that is concentric with the camshaft as described in greater detail herein. As such, depending upon the particular valvetrain configuration, a cam follower may include a roller, finger, arm, or pad, for example, in contact with the cam profile. The cam follower may pivot about various types of fulcrums and positions of pivot points including a ball/socket configuration and a roller shaft, for example. Similarly, depending upon the particular type of engine and valvetrain, a cam follower may also refer to a lifter, tappet, roller follower, or finger follower, for example. Those of ordinary skill in the art will recognize various other engine and/or valvetrain configurations in which a cam follower having a positioning device that reacts to movement of a hydraulic lash adjuster according to the present disclosure may be beneficial. 
     As shown in the partial cut-away/cross-section of a representative application in  FIG. 1 , multiple cylinder internal combustion engine  10  includes at least one camshaft  12  disposed within a cylinder head  14  secured to an engine block  16 , and may be referred to as an overhead cam (OHC) engine. Each cylinder  18  includes a reciprocating piston  20  coupled by a connecting rod to a crankshaft (not shown) as well known in the art. Cylinder head  14  provides conventional intake  22  and exhaust  24  ports having associated gas exchange valves  28 , which include at least one intake valve  30  and at least one exhaust valve  32 . Cylinder head  14  includes conventional hardware such as valve guides or bushings  36  in addition to valve seats and various other hardware (not shown) associated with operation of gas exchange valves  28 . 
     Engine  10  includes a mechanically operated valvetrain  50  to actuate gas exchange valves  28  to control intake of air and/or fuel (for port injected engines) into cylinder  18  through intake port  22  and exhaust of combustion gases through exhaust port  24 . Valvetrain  50  includes valves  28 , valve springs  52 , an intake rocker arm assembly  54  and an exhaust rocker arm assembly  56  mounted for pivoting or limited rotation about corresponding stationary roller shafts or fulcrum shafts  60 ,  62 . Roller shafts  60 ,  62  extend generally parallel to camshaft  12  and are secured by support towers  66 ,  68  disposed within cylinder head  14 . Roller shafts  60 ,  62  may include one or more channels for providing pressurized hydraulic fluid or lubricating oil to rocker arms  54 ,  56  and operating corresponding hydraulic lash adjusters  72 ,  74  contained therein (best illustrated in  FIG. 2 ). Camshaft  12  includes one or more eccentric cams  76 ,  78  having a desired profile or lobe to actuate valves  28 . In addition, camshaft  12  may include one or more concentric cams  80  having a profile that is substantially concentric with the central shaft of camshaft  12  to position corresponding rocker arms  54  while deactivated for subsequent coupling or engagement during activation as described herein. 
     As shown in  FIG. 1 , engine  10  includes at least one gas exchange valve  28  associated with at least one selectively deactivated cylinder  18  to provide operation in a reduced or variable displacement mode. In the embodiment illustrated, intake valve  30  may be selectively deactivated while operating in a reduced displacement mode as described in greater detail herein. While a two valve-per-cylinder engine having one of the valves selectively deactivated to provide reduced displacement is shown for ease of illustration and description, the present disclosure includes applications and embodiments not specifically illustrated with multiple valves-per-cylinder selectively activated or deactivated in response to a command signal from an engine controller. Similarly, the present disclosure includes embodiments having exhaust valves selectively deactivated and embodiments where intake and exhaust valves are selectively deactivated during operation in one or more reduced displacement operating modes. Representative applications include engines having multiple cylinders selectively activated or deactivated as a group by disabling associated intake and/or exhaust valves. Likewise, embodiments of the present disclosure may be used in applications having multiple reduced displacement modes with individually controllable valves/cylinders or multiple groups of controllable valves/cylinders corresponding to different displacements, for example. 
     In the representative embodiment of  FIG. 1 , intake valve rocker arm  54  is selectively coupled to an adjacent eccentric cam follower or rocker arm  90  by an associated pin  92  extending through rocker arm  54  and rocker arm  90  when cylinder  18  is activated. The position of pin  92  is controlled by a hydraulic mechanism (not show) in response to a command from the engine/vehicle controller to selectively couple and uncouple rocker arm  54  to rocker arm  90  (best shown in  FIGS. 2-4 ) for activation and deactivation, respectively, of cylinder  18 . Rocker arm  54  includes a positioning device  100  that positions rocker arm  54  within a desired coupling range by opposing movement of hydraulic lash adjuster  72  while deactivated to facilitate coupling of rocker arm  54  to rocker arm  90  for activation of intake valve  30 . While deactivated or uncoupled, positioning device  100  of rocker arm  54  contacts concentric cam  80  of camshaft  12  and maintains position of rocker arm  54  within a desired coupling range for subsequent coupling via pin  92 . The external profile of cam  80  is substantially concentric with the central shaft of camshaft  12  such that rotation of camshaft  12  does not result in any reciprocating motion of rocker arm  54  and the force of spring  52  maintains valve  30  in a closed position (deactivated). During activation, pin  92  couples rocker arm  54  to eccentric cam follower  90 , which is in contact with a corresponding eccentric cam  76  while cam  76  rotates through the base circle (concentric) portion of its profile. As the associated eccentric cam  76  continues to rotate, cam follower  90 , and rocker arm  54 , which is now coupled to cam follower  90  via pin  92 , move in response and open valve  30 . 
     Rocker arm  54  includes a hydraulic lash adjuster  72  of conventional design (best shown in  FIG. 2 ) that operates to remove lash or space between components of the valvetrain as the components vary during operation due to temperature changes, wear, etc. Lash adjuster  72  uses pressurized hydraulic fluid, such as lubricating oil supplied by the engine oil pump through roller shaft  60  and rocker arm  54 , to provide a fluid coupling that can extend/retract relative to rocker arm  54  to remove lash from the system. According to the present disclosure, positioning device  100  opposes motion or movement of lash adjuster  72  while rocker arm  54  is disengaged or deactivated to maintain the coupling hole of rocker arm  54  in a desired position or within a desired coupling range to facilitate engagement of pin  92  during subsequent valve activation. 
     With continuing reference to  FIG. 1 , although exhaust valve  32  is associated with a selectively deactivated or variable displacement cylinder  18 , exhaust valve  32  may be actuated by a rocker arm  56  of conventional design having a conventional hydraulic lash adjuster  74 . As such, exhaust valve  32  is actuated by rocker arm  56 , which remains in contact with an associated eccentric cam  78  on camshaft  12  whether cylinder  18  and intake valve  30  is activated or deactivated. In the embodiment illustrated in  FIGS. 7-8 , both the intake valve and exhaust valve associated with a particular cylinder are selectively deactivated during operation in a reduced displacement mode. 
       FIG. 2  illustrates one embodiment of a rocker arm having a positioning device according to the present disclosure. Rocker arm  54  includes a hydraulic lash adjuster  72  in a first end  200  that engages the selectively deactivated intake or exhaust valve. Positioning device  100  is disposed on a second end  202  of rocker arm  54 . Rocker arm  54  includes a through hole  210  for mounting on a stationary roller shaft  60  ( FIG. 1 ) and a coupling hole  212  adapted to receive a coupling pin  92  ( FIG. 1 ) to selectively couple rocker arm  54  to an adjacent rocker arm  90  ( FIG. 1 ) during valve activation. An oil hole  214  extends from hole  210  above coupling hole  212  through end  200  to provide pressurized lubricating oil for valvetrain lubrication and for operation of hydraulic lash adjuster  72 . 
     Positioning device  100  includes a lever or lever arm  220  pivotally secured to rocker arm supports  222  by an associated pin  230  extending therethrough, which functions as a fulcrum for lever arm  220 . A spring  224  is disposed between lever arm  220  and rocker arm  54  to resiliently bias a wear-resistant cam follower surface or pad  226  relative to rocker arm  54 . Other applications and implementations may use different types of resiliently biased cam followers. For example, a resiliently biased cam follower may be implemented by a roller follower mounted on a spring-biased axle, for example. Similarly, the cam follower may be implemented by an arm that extends from only one side of the pivot pin  230 , similar to the embodiment illustrated and described with reference to  FIGS. 5-9 , or by an arm that extends from both sides of the fulcrum and that has a spring  224  or other biasing element, such as a pneumatic or hydraulic cell or cylinder on either or both sides of the fulcrum. 
     In the representative embodiment illustrated in  FIG. 2 , lever arm  220  extends on opposite sides of fulcrum or pivot pin  230  to provide a biasing spring  224  on one side and a fixed or adjustable spacer or positive stop  238  on an opposite side of the fulcrum relative to spring  224 . Spacer or positive stop  228  may be associated with lever arm  220  and/or rocker arm  54 , i.e. stop  228  may extend only from rocker arm  54 , only from lever  220 , or from both lever arm  220  and rocker arm  54 , and may be implemented by a fixed pad or an adjustable device. Where an adjustable device is provided, spacer/stop  228  may be used to provide a fine adjustment of the rocker arm position during assembly. Alternatively, selection of a spring  224  among springs having slightly different lengths could be used to adjust the resting or deactivated position of rocker arm  54  during assembly. In one representative embodiment, spacer/stop  228  is implemented by a threaded stud  232  movable within a corresponding threaded hole within end  234  of lever arm  220  to increase or decrease the minimum space between rocker arm  54  and lever arm end  234 . 
     Hydraulic lash adjuster  72  is generally of conventional design and fits within a bore  252  in end  200  of rocker arm  54 . Lash adjuster  72  includes a sleeve  250  having a closed end and an open end with a one or two-piece plunger  262  disposed therein. Plunger  262  defines a low-pressure chamber  254  therein, and a high-pressure chamber  256  between the closed end of sleeve  250  and the plunger  262 . Low-pressure chamber  254  and high-pressure chamber  256  are separated by a spring biased check-valve  258 , which allows hydraulic fluid to flow from low-pressure chamber  254  into high-pressure chamber  256 . Plunger  262  extends from, or retracts into, sleeve  250  based on the volume of hydraulic fluid within high pressure chamber  256  to provide an adjustable length fluid coupling between rocker arm  54  and an associated valve. Hydraulic fluid escapes from high-pressure chamber  256  through a rate-controlled leak-down path formed by clearance between sleeve  250  and plunger  262 . Plunger  262  may include a convex end with a lubricating hole  260  to provide lubricating oil to the associated intake/exhaust valve stem. 
     In operation, lash adjuster  72  essentially eliminates any lash or clearance between the valve train components under varying operating and ambient conditions to provide consistent and reliable valve actuations including repeatable valve opening and closing times and peak lift values. As the length of an associated valve stem varies due to temperature variation or wear, hydraulic fluid from a pressurized supply is fed through stationary shaft  60  into channel  214  of rocker arm  54 . The pressurized hydraulic fluid, which is preferably engine lubricating oil, flows into hole  252  and through sleeve  250  into low-pressure chamber  254  of plunger  252 . A small amount of hydraulic fluid passes through check valves  258  into high-pressure chamber  256  moving plungers  262  away from closed end of sleeve  250  to remove any lash or clearance. As plunger  252  extends, spring  224  of positioning device  100  acts on rocker arm  54  relative to the associated concentric cam so that lash adjuster  72  is maintained at approximately the middle of its range of travel and coupling hole  212  is maintained within a desired coupling range for subsequent alignment with the coupling hole of an adjacent cam follower and engagement of the coupling pin so that rocker arm  54  can be actuated by the eccentric cam associated with the adjacent rocker arm. 
     In a similar fashion, if valve stem increases in length due to thermal expansion, hydraulic fluid slowly escapes from high-pressure chambers  256  between plungers  262  and sleeves  250  to retract plunger  262  with positioning device  100  reacting in response to the lash adjuster movement to maintain coupling hole  212  within a desired coupling range. 
       FIG. 3  is a side view and  FIG. 4  is a perspective view of a valvetrain illustrating operation of a selectively deactivated gas exchange valve using a rocker arm having a positioning device according to one embodiment of the present disclosure.  FIGS. 3 and 4  illustrate a rocker arm  54  and adjacent rocker arm  90  mounted on roller shaft  60  and having corresponding coupling holes aligned. Rocker arm  90  has one end following the profile of an eccentric cam lobe  76  on camshaft  12  and the opposite end in contact with spring  110 , which reacts against the cylinder head (not shown) to keep rocker arm  90  in constant contact with cam  76 . Rocker arm  54  has one end with positioning device  100  ( FIGS. 1-2 ) following the profile of concentric cam  80  on camshaft  12  and the opposite end in contact with the valve stem via the hydraulic lash adjuster as previously described. Valve spring  52 , which is also secured to the valve stem, reacts against the cylinder head (not shown) to keep valve  30  closed and to keep rocker arm  54  in constant contact with cam  80  while valve  30  is deactivated. 
     During operation with valve  30  deactivated, as camshaft  12  rotates, eccentric cam  76  produces reciprocating motion of rocker arm  90  against spring  110 . However, rocker arm  54  remains substantially stationary due to the opposing force of valve spring  52  and that rocker arm  54  contacts concentric cam  80  with positioning device  100  ( FIGS. 1-2 ), which opposes movement of hydraulic lash adjuster  72  ( FIGS. 1-2 ) while deactivated. As such, the coupling hole of rocker arm  54  remains in a substantially stationary position within a desired coupling range as the coupling hole of rocker arm  90  moves across in a somewhat arcuate reciprocating fashion. In response to an activation signal from the engine/vehicle controller, an associated hydraulic activation device (not shown) extends a coupling pin through the corresponding coupling holes of rocker arm  54  and rocker arm  90  when they are aligned (as illustrated in  FIGS. 3-4 ) so that rocker arm  54  moves together with rocker arm  90  and moves in response to eccentric cam  76  to open valve  30  against the spring force of springs  52  and  110 . 
     Additional embodiments of engine valvetrains having rocker arms with a positioning device that opposes hydraulic lash adjuster motion according to the present disclosure are illustrated in  FIGS. 5-9 . Primed reference numerals refer to elements that generally have a similar structure and/or function as previously described elements having corresponding unprimed reference numerals unless otherwise indicated. 
     Another embodiment of a rocker arm  54 ′ is shown in the perspective views of  FIGS. 5 and 7 , and the partial cross-sectional view of  FIG. 6 . Rocker arm  54 ′ includes a positioning device  100 ′ to provide resilient contact with a corresponding camshaft as previously described. In this embodiment, positioning device  100 ′ includes a contact arm  220 ′ pivotably secured to rocker arm  54 ′ by a pin  230 ′ extending through corresponding supports  222 ′ of rocker arm  54 ′. Contact arm  220 ′ includes a wear-resistant contact surface  226 ′ and extends from the pivot point at pin  230 ′ to an adjustable positive stop  228 ′. As illustrated and described in  FIGS. 6-7 , adjustable positive stop  228 ′ can be adjusted during valvetrain assembly to increase or decrease the maximum travel of spring  224 ′, which determines the deactivated or resting position of rocker arm  54 ′ relative to an associated concentric cam on the camshaft. Adjustable positive stop  228 ′ includes a threaded bolt  232 ′ that engages a corresponding threaded portion of a counterbored hole  310  in rocker arm  54 ′. Contact arm  220 ′ includes a complementary (unthreaded) counterbored hole  312  to form a pocket for receiving spring  224 ′. 
     As best shown in  FIGS. 5 and 7 , the adjustable positive stop  228 ′ of contact arm  220 ′ may include a plurality of notches, grooves, or similar features  330  in the upper surface of boss  352  that cooperate with protrusions  314 - 318  on the underside of adjustment bolt  232 ′ to provide a locking feature. In the representative embodiment illustrated, boss  352  includes four equally spaced V-shaped notches and bolt  232 ′ includes four equally spaced hemispherical protrusions. To adjust the position of positive stop  228 ′, contact arm  220 ′ is moved against the force of spring  224 ′ while turning bolt  232 ′ to increase or decrease the maximum travel of spring  224 . When contact arm  220 ′ is released, the force of spring  224 ′ acting on the threads of bolt  232 ′ cooperates with the complementary locking features of bolt  232 ′ and boss  352  so that positive stop  228 ′ maintains its position during operation of the valvetrain. Those of ordinary skill in the art will recognize that the quantity, geometry, positioning, spacing, etc. of complementary locking features may vary depending upon the particular application and implementation. For example, bolt  232 ′ may include two protrusions with boss  352  having six or eight grooves depending on the desired number of locking positions, the thread pitch of the fastener, etc. Similarly, boss  352  may include protrusions that cooperate with dimples in fastener  232 ′, etc. 
     Another embodiment of an internal combustion valvetrain having mechanically actuated selectively deactivated gas exchange valves is illustrated in the front view of  FIG. 8  and the top view of  FIG. 9 . In this representative embodiment, both intake valve  30 ′ and exhaust valve  32 ′ are selectively deactivated for operation in a reduced displacement mode. Valvetrain  50 ′ incorporates rocker arms  54 ′ that each include a positioning device  100 ′ as illustrated and described with reference to  FIGS. 5-7 . As shown in the top view of  FIG. 9 , the positioning devices  100 ′ for both rocker arms  54 ′ contact a common concentric cam  80  on camshaft  12  when deactivated. Cam followers  90 ′ each include a roller  400  in contact with an associated eccentric cam  76  for operation of intake valve  30 ′, and eccentric cam  78  for operation of exhaust valve  32 ′ when coupled to corresponding rocker arms  54 ′. 
     As illustrated in  FIGS. 1-9 , a method for operating engine  10  and valvetrain  50  to selectively activate and deactivate a gas exchange valve  28  according to the present disclosure includes positioning a rocker arm  54  having a hydraulic lash adjuster  72  within a desired coupling range by opposing movement of the hydraulic lash adjuster  72  while the gas exchange valve  28  is deactivated and the rocker arm  54  is uncoupled from movement with an eccentric cam  76  to facilitate coupling of the rocker arm  54  for movement with an eccentric cam  76  during activation of the gas exchange valve  28 . In one embodiment, a method of the present disclosure includes positioning the rocker arm  54  by resiliently biasing a cam follower  100  pivotally secured to the rocker arm  54  relative to a concentric cam  80  associated with the gas exchange valve  28  such that movement of the hydraulic lash adjuster  72  results in movement of the rocker arm  54 . In one representative embodiment, rocker arm  54  is positioned within a desired coupling range by contacting a cam  80  with a spring-biased lever  220  secured to one end  202  of the rocker arm  54 . Embodiments may include limiting movement of the spring-biased lever  220  with an adjustable stop  232  disposed on at least one of the lever  220  and the rocker arm  54 . In one embodiment, positioning the rocker arm  54  within a desired coupling range comprises automatically adjusting the position of rocker arm  54  in response to movement of the hydraulic lash adjuster  72  such that a coupling hole  212  disposed between a fulcrum and the hydraulic lash adjuster  72  is positioned for alignment with a coupling pin  92  extending through an adjacent rocker arm  90  during activation of the intake and/or exhaust valve  30 . 
     As such, embodiments of an internal combustion engine and associated valvetrain having a rocker arm with a positioning device according to the present disclosure provide various advantages. The spring-loaded positioning device maintains the rocker arm in a desired latching position for coupling with an associated rocker arm or eccentric cam follower during activation of the valve so that the same eccentric cam profiles may be used for cylinders that can be deactivated and those without deactivation capability. Eliminating design compromises by replacing modification of the cam profiles with a compensating positioning device according to the present disclosure provides more optimized cam profiles to improve durability and combustion performance while reducing noise. 
     While the best mode has been described in detail, those familiar with the art will recognize various alternative designs and embodiments within the scope of the following claims. Various embodiments may have been described as providing advantages or being preferred over other embodiments or prior art implementations in regard to one or more desired characteristics. However, as one skilled in the art is aware, one or more characteristics may be compromised to achieve desired system attributes, which depend on the specific application. These attributes include, but are not limited to: cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. Any embodiments described herein as less desirable relative to another embodiment or the prior art with respect to one or more characteristics are not outside the scope of the following claims.