Patent Description:
Internal combustion engines require valve actuation systems to control the flow of combustible components, typically fuel and air, to one or more combustion chambers during operation. Such systems control the motion and timing of intake and exhaust valves during engine operation. In a positive power mode, intake valves are opened to admit fuel and air into a cylinder for combustion and exhaust valves are subsequently opened to allow combustion products to escape the cylinder. This operation is typically called a "positive power" operation of the engine and the motions applied to the valves during positive power operation are typically called "main event" valve actuation motions. Auxiliary valve actuation motion, such as motion that results in engine braking (power absorbing), may be accomplished using "auxiliary" events imparted to one or more of the engine valves.

Valve movement during main event positive power modes of operation is typically controlled by one or more rotating cams as motion sources. Cam followers, push rods, rocker arms and other elements disposed in a valvetrain provide for direct transfer of motion from the cam surface to the valves. The use of a valve bridge may impart motion to plural valves from a single upstream valvetrain. For auxiliary events, "lost motion" devices may be utilized in the valvetrain to facilitate auxiliary event valve movement. Lost motion devices refer to a class of technical solutions in which valve motion is modified compared to the motion that would otherwise occur as a result of actuation by a respective cam surface alone. Lost motion devices may include devices whose length, rigidity or compressibility is varied and controlled in order to facilitate the selective occurrence of auxiliary events in addition to, or as an alternative to, main event operation of valves. Auxiliary events may also be facilitated by dedicated cam systems in which a separate auxiliary or braking cam and valvetrain may be used to impart auxiliary motion to one or more valves to facilitate the selective occurrence of auxiliary events. An apparatus for actuating two engine valves in an internal combustion engine comprising a main event motion source and an auxiliary event motion source is disclosed by <CIT>.

Lash adjustment features are typically provided on valve actuation systems to facilitate the elimination of lash, which is excessive clearance between valvetrain components that can lead to excessive noise, vibration, impact forces and wear. For example, during braking events, substantial lash may be introduced into the engine valvetrain. Lash adjusters, which are typically hydraulic lash adjusters ("HLA's"), may include mechanical components that cooperate to expand under hydraulic pressure in a lash take-up mode during one portion of the valve cycle, typically when the valvetrain is under zero lift or unloaded, and then assume a hydraulically "locked" or incompressible mode during valve opening portion of the valve cycle, typically when the valvetrain is under high load, for example, during a main event actuation. One challenge related to the use of HLA's is the prevention of over-extension or "jacking" of the HLA, which may occur when the HLA is permitted to extend too far in the take-up mode and becomes hydraulically locked in the over-extended position. This can result in excessive valvetrain forces and other undesirable consequences. As such measures have been taken in the prior art to prevent jacking by maintaining suitable loads on the HLA or to limit HLA extension.

Lost motion cam systems typically use at least one cam with different profiled lift sections on the same cam lobe to impart motion for respective main event and one or more auxiliary events. These different profiled lift sections are activated or deactivated using a separate lost motion mechanism, such as a piston or actuator, located in the valvetrain. Example auxiliary events include engine braking, early exhaust valve opening (EEVO), or late intake valve closing (LIVC) lift events, and can be imparted to one or more valves in a valve set (i.e., two exhaust valves for a respective cylinder). Lost motion auxiliary valve lift systems, such as lost motion braking systems may employ a single rocker associated with the lost motion cam and a valve bridge associated with the rocker for actuating two engine valves in main event motion. Auxiliary valve lift or braking motion on one of the valves is facilitated by an auxiliary valve lift or braking actuator, which is a lost motion device that may be housed in the rocker and may selectively impart auxiliary or braking motion to the valve by way of a bridge pin disposed in the bridge and providing for independent motion relative thereto. The auxiliary valve lift or braking actuator is selectively activated and deactivated such that the auxiliary or braking event lift profile section or lobe on the lost motion cam only results in auxiliary or braking motion on the valve when an auxiliary event, such as engine braking is desired.

On the other hand, dedicated cam valve actuation systems may utilize a dedicated auxiliary motion source and dedicated auxiliary valvetrain components, at least some of which are separate from the main event motion source and valvetrain, to facilitate auxiliary events. <CIT>, for example, describes a dedicated cam system in which main event motion is imparted to a valve bridge and ultimately to two engine valves cooperating therewith. Auxiliary motion of one of the engine valves may be facilitated by a dedicated auxiliary motion source (cam) which cooperates with an auxiliary rocker to transmit auxiliary motion through a bridge pin in the valve bridge, and ultimately to one engine valve to cause auxiliary events, such as braking events.

Dedicated cam valve actuation systems may include systems commonly known as "Type II" valvetrain architectures, as described in SAE Technical Paper <NUM>-<NUM>-<NUM>, titled "Design and Development of a <NUM>-Step Rocker Arm. " These architectures may include a rocker arm that pivots about a fulcrum at one end, with an opposite end engaging a valve or valvetrain components cooperating with a valve. Main event motion may be imparted at a central or intermediate location on the rocker arm by a main event motion source, such as a main event cam. These systems may utilize lash adjusters. In Type II architectures, the lash adjuster may not be disposed directly in the main event load path but may instead serve as a reaction force to the main event load and be disposed, for example, in a position in which lash is adjusted by relative movement of the rocker arm pivot.

In engine environments where auxiliary motion is facilitated by a dedicated auxiliary motion source, such as a dedicated cam and rocker, or a bolt-on master/slave brake, which may be separate from the main event motion source, in the above-described Type II architectures and other environments, challenges in preventing lash adjuster over-extension may be presented.

It would therefore be advantageous to provide systems that address the aforementioned shortcoming and others in the prior art.

Responsive to the foregoing challenges, the instant disclosure provides various embodiments of valve actuation systems with features for controlling and preventing over-extension of lash adjusters, which may be applied in both lost-motion and dedicated cam auxiliary motion systems. More particularly, the disclosure describes systems in which a lash adjuster loading component may cooperate, either directly or indirectly through other valvetrain components, with a lash adjuster to prevent over-extension thereof. The lash adjuster loading component may be disposed in or cooperate with various elements in the valvetrain and may apply or facilitate the application of a biasing force on the lash adjuster at times during the engine cycle when the lash adjuster may be otherwise prone to over-extension. The described systems therefore facilitate lash adjuster operation and reduced risk of lash adjuster over-extension or "jacking" in both integrated lost motion as well as dedicated auxiliary cam/valvetrain engine environments.

According to one aspect, a system for actuating at least one of two or more engine valves in an internal combustion engine comprises a main event motion source adapted to provide main event motion to the at least one engine valves, a main event valvetrain for transmitting motion from the main event motion source through a main event load path to the at least one valve; an auxiliary event motion source, separated from the main event motion source; an auxiliary event valvetrain for transmitting the auxiliary event motion source to one or more engine valves through a second load path; a lash adjuster cooperating with the first load path and adapted to take up lash in the main event valvetrain of the at least one engine valve; a lash adjuster loading component adapted to prevent over-extension of the lash adjuster.

According to another aspect of the disclosure, an apparatus or system for actuating at least one of two or more engine valves that may be particularly suited for dedicated cam systems in an internal combustion engine may comprise a main event motion source, a main event valvetrain for transmitting motion from the main event motion source to the valve bridge through a first load path, an auxiliary event motion source, separate from the main event motion source, an auxiliary event valvetrain for transmitting motion from the auxiliary motion source to one of the two or more engine valves through a second load path, a lash adjuster disposed in the first load path, and a lash adjuster loading component disposed in the first load path for preventing over-extension of the lash adjuster. The lash adjuster loading component may comprise a stroke-limited, spring-loaded piston disposed in a valve bridge, or other main event valvetrain component, such as a rocker, and may have a fixed stroke defined by upper and lower limits and a biasing component, such as a compression spring, for biasing the piston against the lash adjuster to control the lash adjuster extension during auxiliary events. The lash adjuster loading component may assume a lash adjuster refill state, which permits refill of the lash adjuster, a preload state, in which the lash adjuster loading component applies a biasing force to the lash adjuster, and a main event state, in which the lash adjuster loading component transmits high loads from the main event motion source to the valve bridge. The main event motion source may include a preload cam surface and a lash adjuster refill cam surface in addition to the main event lift surface to cause the lash adjuster loading component to assume the lash adjuster refill and preload states during operation. The lash adjuster loading component may thus provide control of lash adjuster refill and prevent lash adjuster over-extension in operational environments that may include a separate main event and auxiliary motion sources.

According to another aspect of the disclosure, an apparatus or system for actuating at least one of two or more engine valves that may be particularly suited for dedicated cam systems in Type II valvetrain architectures in an internal combustion engine. The system may comprise a main event motion source, a main event valvetrain for transmitting motion from the main event motion source to the valve bridge through a first load path, an auxiliary event motion source, separate from the main event motion source, an auxiliary event valvetrain for transmitting motion from the auxiliary motion source to an engine valve through a second load path, a lash adjuster, and a lash adjuster loading component cooperating with the first load path for preventing over-extension of the lash adjuster. The lash adjuster loading component may comprise a stroke-limited, spring-loaded piston or a spring-loaded lever arm disposed in or cooperatively associated with an end pivoted rocker arm, a pivot, or another valvetrain component. The spring biased piston may have a fixed stroke defined by upper and lower limits and a biasing component, such as a compression spring, for biasing the piston against the lash adjuster to control the lash adjuster extension during auxiliary events. The lash adjuster loading component may assume a lash adjuster refill state, which permits refill of the lash adjuster, a preload state, in which the lash adjuster loading component applies a biasing force to the lash adjuster, and a main event state, in which the lash adjuster loading component transmits high loads from the main event motion source to the valve bridge. The main event motion source may include a preload cam surface and a lash adjuster refill cam surface in addition to the main event lift surface to cause the lash adjuster loading component to assume the lash adjuster refill and preload states during operation. The lash adjuster loading component may thus provide control of lash adjuster refill and prevent lash adjuster over-extension in Type II operational environments that may include a separate main event and auxiliary motion sources.

Other aspects and advantages of the disclosure will be apparent to those of ordinary skill from the detailed description that follows and the above aspects should not be viewed as exhaustive or limiting. The foregoing general description and the following detailed description are intended to provide examples of the inventive aspects of this disclosure and should in no way be construed as limiting or restrictive of the scope defined in the appended claims.

The above and other attendant advantages and features of the invention will be apparent from the following detailed description together with the accompanying drawings, in which like reference numerals represent like elements throughout. It will be understood that the description and embodiments are intended as illustrative examples according to aspects of the disclosure and are not intended to be limiting to the scope of invention, which is set forth in the claims appended hereto.

The functionality of components in an example valve actuation system according to aspects of the disclosure will first be explained generally, followed by a description of a more detailed example implementation. These general and example descriptions are intended to be illustrative and not exhaustive or limiting with regard to the inventions reflected in this disclosure.

<FIG> is a schematic block diagram of a valve actuation system <NUM> according to aspects of the disclosure. A valve actuation motion source <NUM> may include main event motion source components <NUM> and auxiliary event motion source components <NUM>. For example, the valve actuation motion source <NUM> may comprise a cam and camshaft driving components. The main event motion source components <NUM> may comprise a main event cam lobe on the cam and the auxiliary event motion source <NUM> may comprise one or more auxiliary or lost motion cam lobes on the cam.

Motion from the motion sources <NUM> and <NUM> is transferred to valvetrain <NUM>, which may comprise main event motion valvetrain components <NUM> and auxiliary event motion valvetrain components <NUM>. It will be recognized that the valvetrain motion components <NUM> and <NUM> may comprise common elements. For example, the main event motion valvetrain components <NUM> and the auxiliary event motion valvetrain components <NUM> may utilize a common cam follower and a common rocker arm. Main event valvetrain components <NUM> may include a lash adjuster <NUM>, which may be a hydraulic lash adjuster.

A lash adjuster <NUM> may be disposed in one of the main event motion valvetrain components <NUM>, in which case that component can function as a housing for the lash adjuster. A lost motion assembly <NUM> may be included in the auxiliary event motion valvetrain components <NUM>, in which case the component can function as a housing for the lost motion assembly.

The valvetrain <NUM> and components thereof cooperates with the valve bridge <NUM>, which may impart motion to engine valves <NUM> and <NUM>. According to an aspect of the disclosure, a lash adjuster loading component <NUM> may be housed in the valve bridge <NUM> and may cooperate with the lash adjuster <NUM> to keep the lash adjuster in a loaded state (i.e., with a force against the extended direction of the lash adjuster). Valve bridge <NUM> may also house an auxiliary motion bridge component <NUM>, which may be a component that permits transfer of motion from the lost motion assembly <NUM> to a braking engine valve <NUM> without imparting motion to the valve bridge <NUM>.

<FIG> is a schematic illustration of a valve actuation system <NUM> in an implementation which is consistent with the functional block diagram of <FIG>. A valve actuation motion source may be a lost motion cam <NUM> including a main event lobe <NUM> and auxiliary event lobes <NUM> and <NUM>. Auxiliary events may include, but are not limited to, braking events, such as compression release (CR) braking, EEVO, LIVC or exhaust gas recirculation (EGR). Referring additionally to <FIG>, further details of a lost motion cam are illustrated. An example profile of a lost motion cam may include a main event lobe profile <NUM>, and auxiliary event lobe profiles <NUM> and <NUM>. Corresponding motions are transmitted to the rocker arm <NUM> during each full rotation of the lost motion cam <NUM>. Such motions may be selectively further transmitted to other valvetrain components, as will be further explained, to effect desired motion on the engine valves during main event and auxiliary events.

A rocker arm <NUM> includes a cam follower <NUM> and is mounted for pivoting or rotational movement about a rocker arm shaft (not shown) extending through rocker arm journal <NUM>. Rocker arm <NUM> may include a first bore <NUM> for housing an inboard valve actuator <NUM> and a second bore <NUM> for housing an HLA <NUM>. As those of ordinary skill in the art will recognize, rocker arm <NUM> will typically include a fluid passage <NUM> (represented schematically) therein for providing a constant supply of pressurized hydraulic fluid from the rocker arm journal <NUM> interior surface to the second bore <NUM> and the HLA. A vent <NUM> may provide for outflow of the hydraulic fluid from the piston bore <NUM>. The hydraulic fluid is typically supplied via the rocker arm shaft (not shown). As is known in the art, the HLA may passively assume a lash adjustment mode, in which it fills with pressurized hydraulic fluid through ported passages in the rocker arm such that the HLA expands to take up lash in the valvetrain, and a hydraulically "locked" mode in which it is hydraulically isolated the hydraulic fluid within it is checked against outflow and therefore incompressible, essentially functioning as a solid component. HLA may support a pivot <NUM> and a cooperating pedestal or foot <NUM>, which may pivot or rotate relative to the pivot <NUM>, thus providing for pivoting movement of the valve bridge <NUM>, to some degree. Passage <NUM> may include a control valve for preventing backflow of oil from the actuator piston circuit when load is applied.

In this implementation, according to inventive aspects of the disclosure, the HLA is subject to the stroke-limited compressive force provided by a lash adjuster loading component in the form of the stroke limited piston <NUM> disposed in a bore <NUM> in the valve bridge <NUM>. The stroke of the lash adjuster loading component is biased in a way that compresses the HLA, but is also limited by a stroke limiter <NUM> to prevent over compression of the HLA. A compression spring <NUM> is disposed in an internal bore <NUM> of the piston <NUM> and engages an end wall <NUM> thereof. An opposite end of compression spring <NUM> engages a bottom wall <NUM> of the valve bridge bore <NUM> and thus provides an upward force on the piston <NUM>. A stroke limiter <NUM>, which may be a snap ring or retaining ring fastened to the valve bridge <NUM>, may engage and prevent upward travel of a shoulder <NUM> of the piston <NUM> and thus limits the upward movement of the piston <NUM> relative to the valve bridge <NUM>.

Main event valve motion may be conveyed along a first load path from motion source (lost motion cam) <NUM> to the two engine valves <NUM>, <NUM>. More particularly, the first load path may be defined by the cam follower <NUM>, rocker arm <NUM>, the HLA <NUM> and the valve bridge <NUM>. The first load path from the motion source to the engine valves may thus include valvetrain components of the cam follower <NUM>, rocker arm <NUM>, and HLA, including the pivot <NUM> and pedestal <NUM>.

Auxiliary motion, such as braking motion, may be imparted to one of the engine valves <NUM>, via a second load path, which includes the inboard valve actuator <NUM>. An auxiliary motion bridge component, in this case in the form of bridge pin <NUM>, may provide for the transfer of motion, separate from motion of the valve bridge <NUM>, from the inboard valve actuator <NUM> to the braking valve <NUM>. Inboard valve actuator <NUM> is a lost motion assembly or device, which may be selectively hydraulically activated and deactivated, via a switched hydraulic passage <NUM>, at appropriate times during an engine cycle to effect auxiliary events, such as engine braking. Switched hydraulic passage <NUM> provides hydraulic fluid to piston bore <NUM>, typically from an axially extending passage (not shown) in the rocker shaft which provides hydraulic fluid to a number of valve rockers mounted on the shaft. In an activated state, a piston <NUM> forming the inboard valve actuator <NUM> may be extended out of a corresponding piston bore <NUM> and maintained in an incompressible or solid extended state and thus transfer motion. In a deactivated state, the actuator piston <NUM> of the inboard valve actuator may be permitted to retract into its bore <NUM>, thereby losing any transferred motion from the rocker arm and thus be in a compressible or motion absorbing state. As will be recognized, in this implementation, a second load path from the motion source to the braking valve <NUM> is defined by the auxiliary event motion valvetrain components (cam follower <NUM>, rocker arm <NUM>, inboard valve actuator <NUM>) and by bridge pin <NUM>.

As will be recognized, in accordance with inventive aspects of the disclosure, the above-described implementation provides separate load paths for the lash-adjusted main event valve actuation and the auxiliary event (braking) valve actuation. In operation, when engine braking is undertaken, inboard valve actuator <NUM> extends to impart motion to the inboard valve <NUM> only, it being recognized that rocker arm <NUM> will, at substantially the same time, have motion imparted by one of the auxiliary lobes on the lost motion cam. As the rocker goes from the inner base circle of the cam to the base circle defined by the auxiliary lobe, the rocker <NUM> will generate more stroke at the HLA, which is disposed at a further distance from the rocker arm pivot (center of the rocker arm shaft) than the inboard valve actuator. The lash adjuster loading component (stroke-limited bridge piston <NUM>) will thus create a compressive load on the HLA and prevent any over-extension or jacking as the inboard side (right side in <FIG>) of bridge <NUM> pivots downward in conjunction with the downward movement of bridge pin <NUM>, which moves under force from the inboard valve actuator <NUM>.

As shown in <FIG>, a clearance exists between the bottom surface of the piston <NUM> and the bottom wall <NUM> of the valve bridge bore. This clearance defines a lost motion travel distance <NUM> for the piston lash adjuster loading component. The lost motion travel distance may be selected to ensure that the auxiliary event motions of the rocker arm <NUM> are "lost" and do not result in undesired motion of the valve bridge <NUM> and engine valves <NUM> and <NUM>. That is, in a braking event, valve <NUM> will be actuated under motion from a braking lobe in the cam <NUM> transmitted via the inboard valve actuator, while the motion of the rocker arm <NUM> and HLA will be "lost" via the stroke limited piston <NUM> and not transmitted to the valve bridge or engine valve <NUM> until the piston <NUM> bottoms against bottom wall <NUM> of the valve bridge bore and results in motion of the valve bridge and opening of both valves for main event motion. The lost motion gap is designed to "lose" the motion that would otherwise result from the auxiliary event cam lift profiles, but without losing the main event motion.

<FIG> illustrates an alternative arrangement for a lash adjuster loading component and HLA, according to aspects of the disclosure. In this implementation, features of the stroke limited piston are integrated into the rocker arm rather than the valve bridge (as in <FIG>). This arrangement permits valve braking motion to be accomplished via the same load path in which the lash adjuster is disposed and thus may be used to eliminate the need for an independent valve actuator (inboard valve actuator) for facilitating valve braking motion. In this regard, the load path in which the lash adjuster is disposed (first load path) and the load path in which the auxiliary valve motion actuator is disposed (second load path) are the same. A rocker arm <NUM> may include a bore <NUM> for receiving a stroke limited piston <NUM>, which in turn includes an HLA-receiving bore <NUM> for supporting an HLA therein. A travel limiter <NUM> limits travel (in a downward direction) of piston <NUM>. A compression spring <NUM> is disposed in the rocker arm bore <NUM> and engages a shoulder <NUM> on the piston <NUM> on one end and a bottom bore wall <NUM> on another end, providing a compressive force on the HLA against the bridge (not shown) which is engaged by the pivot <NUM> and pedestal <NUM>. As in the configuration illustrated in <FIG>, the piston <NUM> is configured to define a chamber <NUM> with bore <NUM> and bottom wall <NUM> and to provide a lost motion travel distance <NUM> thereby preventing transmission of auxiliary valve events via the first load path. Piston <NUM> may include an annulus <NUM> which permits flow of hydraulic fluid from a constant (continuous) supply passage <NUM> in the rocker arm <NUM> to the HLA receiving bore <NUM> and the HLA. A switched fluid supply passage <NUM> may provide fluid to the bore <NUM> under control of a control valve <NUM>. Fluid flow from the HLA may be prevented from bore <NUM> by tight clearances between the piston <NUM> and the bore <NUM>. A vent <NUM> may be provided in the piston <NUM> and a check valve <NUM> provided therein to facilitate one-way flow to the HLA. In operation, when activation of the auxiliary motion valve is desired, the hydraulic fluid control valve <NUM> may be switched to provide hydraulic pressure (oil) to chamber <NUM> and extend the lash adjuster loading assembly (piston <NUM>) and lock it in an extended position, thereby initiating valve braking motion. When the control valve <NUM> is switched off, the lash adjuster check valve indexes to an "off" position and chamber <NUM> can vent, by passage of fluid via vent <NUM> and check valve <NUM> to permit the brake to be deactivated. As will be recognized, this configuration permits braking motion to be undertaken via the same load path in which the lash adjuster is disposed. This may be used to eliminate the need for an independent (separate) valve actuator, such as an inboard valve actuator described above, to accomplish auxiliary valve motion.

<FIG> illustrates an alternative arrangement for a lash adjuster loading component and HLA, according to aspects of the disclosure. In this implementation, features of the stroke limited piston are integrated into the rocker arm rather than the valve bridge (as in <FIG>). This arrangement permits valve braking motion to be accomplished a second load path in which the lash adjuster is disposed and thus may be used in implementations utilizing an independent valve actuator (inboard valve actuator as described above) for facilitating valve braking motion. A rocker arm <NUM> may include a bore <NUM> for receiving a stroke limited piston <NUM>, which in turn includes an HLA-receiving bore <NUM> for supporting an HLA therein. A travel limiter <NUM> limits travel (in a downward direction) of piston <NUM>. A compression spring <NUM> is disposed in the rocker arm bore <NUM> and engages a shoulder <NUM> on the piston <NUM> on one end and a bottom bore wall <NUM> on another end, providing a compressive force on the HLA against the bridge (not shown) which is engaged by the pivot <NUM> and pedestal <NUM>. As in the configuration illustrated in <FIG>, the piston <NUM> is configured to define a chamber <NUM> with bore <NUM> and bottom wall <NUM> and to provide a lost motion travel distance <NUM> thereby preventing transmission of auxiliary valve events via the first load path. Piston <NUM> may include an annulus <NUM> which permits flow of hydraulic fluid from a constant (continuous) supply passage <NUM> in the rocker arm <NUM> to the HLA receiving bore <NUM> and the HLA. Fluid flow from the HLA may be prevented from bore <NUM> by tight clearances between the piston <NUM> and the bore <NUM>. In operation, hydraulic fluid is supplied to the lash adjuster via continuous supply passage <NUM> and annulus <NUM>. Chamber <NUM> may be without any hydraulic fluid, i.e., occupied by air. A vent <NUM> may vent air to the outside environment. Air from the lash adjuster may vent to chamber <NUM> via vent <NUM>. As will be recognized, this configuration may be utilized in engine environments eliminate where an independent (separate) valve actuator, such as an inboard valve actuator described above, is utilized to accomplish auxiliary valve motion.

As will be recognized by those of ordinary skill in the art, the embodiments described above with regard to <FIG> and <FIG> may be used in environments where auxiliary motion is applied to at least one valve, with an auxiliary motion source that is separate from the main event motion source. For example, in auxiliary motion systems where auxiliary motion is facilitated by a dedicated rocker arm or bolt-on master slave brake, or any auxiliary motion source that is not necessarily a lost motion main event motion source. The motion of the main event rocker arm may be timed with the auxiliary motion events such that the compression spring (<NUM> in <FIG>, or <NUM> in <FIG>, for example) remains at least partially compressed during these events, but not fully compressed to the point where lift is provided in positive power or during auxiliary lift events. This prevents extension of the lash adjuster during any auxiliary motion events by preloading the lash adjuster with the main event motion.

<FIG> is a schematic block diagram of a valve actuation system <NUM> according to further aspects of the disclosure. This system is similar to the system described above with regard to <FIG>. However, some differences relate to the location of the lash adjuster. More specifically, the lash adjuster <NUM> may disposed in the valve bridge <NUM> along with the lash adjuster loading component <NUM>. Valve actuation motion source <NUM> may include main event motion source components <NUM> and auxiliary event motion source components <NUM>. Motion from the motion sources <NUM> and <NUM> is transferred to valvetrain <NUM>, which may comprise main event motion valvetrain components <NUM> and auxiliary event motion valvetrain components <NUM>. These component sets may include common elements, such as a single rocker arm. A lost motion assembly <NUM> may be included in the auxiliary event motion valvetrain components <NUM>, in which case the component can function as a housing for the lost motion assembly.

The valvetrain components transmit motion to the valve bridge <NUM>, and/or components thereof. A lash adjuster <NUM> and lash adjuster loading component <NUM> may be disposed in the valve bridge <NUM>. An auxiliary motion bridge component <NUM> may be provided as a component to the valve bridge <NUM> and may include, for example, a bridge pin, which permits transfer of motion from the lost motion assembly <NUM> to a braking engine valve <NUM> without imparting motion to the valve bridge <NUM>. According to an aspect of the disclosure, a lash adjuster loading component <NUM> functions to keep the lash adjuster <NUM> in a loaded state (i.e., with a force against the extended direction of the lash adjuster).

<FIG> is a schematic illustration of a valve actuation system <NUM> in an implementation which is consistent with the functional block diagram of <FIG>. Rocker arm <NUM> is driven by lost motion cam <NUM> and includes an inboard valve actuator <NUM>, which cooperates with a bridge pin <NUM> to impart motion to a braking valve <NUM>. Rocker arm <NUM> also includes a static (solid) extended pivot <NUM> extending from and end thereof and having a swivel or ball. Pivot <NUM> cooperates with an e-foot pedestal <NUM> which engages an HLA base <NUM> to impart motion to an HLA/bridge assembly, as further described. A hydraulic fluid passage <NUM> may extend through the pivot <NUM>, the pedestal <NUM> and the rocker arm from the journal to hydraulically actuated components such as the inboard valve actuator <NUM> and HLA <NUM>.

A stroke-limited piston <NUM> is mounted within a bore <NUM> in the valve bridge <NUM>. A shoulder <NUM> may be provided on an upper surface of the piston for engaging a travel limiter <NUM> fastened to the bridge <NUM>. Piston <NUM> also includes an inner annular wall <NUM> configured for housing the components of the HLA. Annular wall <NUM> also defines an annular recess <NUM> which partially houses a compression spring <NUM> to bias the piston in an upward direction. Compression spring <NUM> engages a bottom wall <NUM> of the bridge bore <NUM> and an upper wall defined within the annular recess <NUM> of the piston <NUM>. A lost motion gap having a clearance <NUM> is defined between the bottom end of the piston <NUM> and the bridge bore bottom wall <NUM>.

In operation, during main event (positive power) motion of the engine, the rocker arm <NUM> imparts main event motion from the lost motion cam <NUM> to the valve bridge via pivot <NUM>, pedestal <NUM> and the HLA <NUM>. The constant compressive forces provided on the bridge-located lash adjuster loading component, which includes the spring piston <NUM> and related components, operates to ensure that over-extension or "jacking" of the HLA <NUM> does not occur. During auxiliary motion, when a braking operation is being performed or is active, the motion from the rocker arm <NUM> is transmitted through the activated inboard valve actuator <NUM> to the bridge pin <NUM> and braking valve <NUM>. The motion of the rocker arm, owing to the rocker ratio and respective locations of the inboard actuator and the fulcrum <NUM> on the rocker arm <NUM>, will result in a larger displacement or stroke of the HLA than the stroke undertaken by the inboard valve actuator. This larger stroke will result in a compressive force from the stroke-limited piston <NUM> acting against the HLA to thereby prevent overextension. The lost motion function of the HLA mounting configuration, owing to the clearance <NUM> between the piston <NUM> and the bridge bore bottom wall <NUM> will operate to "hide" the auxiliary motion of the rocker arm from the valve bridge <NUM>, and thus the engine valves <NUM> and <NUM>, it being understood that valve <NUM> will still undergo movement according to the braking action.

<FIG> is a schematic block diagram of a valve actuation system <NUM> according to aspects of the disclosure. In this example system, motion sources <NUM> may include a main event motion source <NUM> and an auxiliary motion source <NUM>. These motion sources may comprise a cam or other device for causing motion to be imparted through respective load paths, represented by the arrows and schematically-represented components (boxes) in <FIG>, and ultimately to one or more engine valves <NUM> and <NUM>. The main event motion source <NUM> and auxiliary event motion source <NUM> may be separate sources, such as separate cams, including a main event cam and an auxiliary event (dedicated or braking) cam. Main event valvetrain components <NUM> transmit main event motion (and load) to engine valves <NUM> and <NUM>. A lash adjuster <NUM>, which may be hydraulic lash adjuster (HLA), may be disposed in the main event load path in order to take up lash between components in the main event valvetrain. Lash adjuster <NUM>, as will be recognized, may include internal components which provide for the lash adjuster to assume an expanding, semi-rigid state when the valvetrain components are under a relatively low load, and a rigid state when the valvetrain components are under high load, such as during main event valve motion.

Auxiliary motion source <NUM> may transmit motion (and load) through an auxiliary event load path, which may include an auxiliary event activation system <NUM> which may selectively transmit or absorb motion in the auxiliary event load path to facilitate the occurrence of an auxiliary event valve motion, such as engine braking, in engine valve <NUM>. One or more auxiliary motion valvetrain components <NUM> may be provided as a subset of the main event valvetrain components <NUM>. For example, the main event valvetrain components <NUM> may include a valve bridge, and the auxiliary motion valvetrain components may include a bridge pin, slidably disposed in the valve bridge, such that the bridge pin transmits main event motion from the bridge during main event valve operation. The bridge pin may move relative to the bridge to transmit auxiliary motion, independent of the bridge main event motion, when the auxiliary event activation system is active to facilitate, for example, engine braking motion in valve <NUM>.

According to an aspect of the disclosure, the main event valvetrain components <NUM> may include a lash adjuster loading component <NUM> disposed in the main event valvetrain. The lash adjuster loading component <NUM> interacts with the lash adjuster <NUM> to prevent over-extension or "jacking" of the lash adjuster <NUM> during engine operation. More specifically, and as will be further detailed below, the lash adjuster loading component <NUM> may maintain a biasing force on the lash adjuster during periods of relatively low load, such as during auxiliary events or during transitions to or from auxiliary events. The biasing force will be of a magnitude that is sufficient to counter the lash adjuster hydraulic force and thus prevent over-extension of the lash adjuster. Further, the lash adjuster loading component <NUM> may permit refill of the lash adjuster <NUM> and will permit high loads to be transmitted to the main event valvetrain, such as loads present in the main event valvetrain during main event valve operation.

<FIG> is a perspective view showing example components of a valve actuation system <NUM> according to aspects of the disclosure, including a valve bridge <NUM> having an integrated lash adjuster loading component <NUM>. While further internal details will be described, <FIG> shows a spring-biased piston <NUM> that extends from the valve bridge <NUM>. An adjusting setscrew <NUM> and locking nut <NUM> may be provided to adjust operational parameters of the spring-biased piston, as will be explained. Valve bridge <NUM> may directly contact the stem of a first engine valve <NUM>, extending through a valve guide <NUM>. A bridge pin <NUM> may be housed for sliding motion in a bore in an opposite end of the valve bridge <NUM> and may interact with the stem of a second engine valve <NUM> to provide for main event and auxiliary motion thereof. Valve <NUM> may extend through a valve guide <NUM>.

<FIG>, <FIG> and <FIG> are cross-sections of the example valve actuation system <NUM> of <FIG>, and including a lash adjuster loading component <NUM> and a lash adjuster <NUM>. These figures show the lash adjuster loading component <NUM> in three different configurations or "states. " Valve bridge <NUM> may include a piston guiding bore <NUM> formed in a central portion thereof for housing piston <NUM> and permitting sliding movement, in a vertical direction relative to <FIG>. Piston <NUM> may have a generally cylindrical shape and cooperate with a biasing component which, in this example, is in the form of a biasing compression spring <NUM>. Spring <NUM> may be partially housed in an internal bore <NUM> of the piston <NUM> with an upper end of spring <NUM> seated against a bore end wall <NUM>. Piston <NUM> may include an annular piston skirt or shoulder <NUM>, which is of a larger diameter than piston guiding bore <NUM>. A valve bridge counterbore <NUM> may be formed on an underside of the bridge <NUM> in general axial alignment with the piston guiding bore <NUM> and having a larger diameter and internal threads <NUM>. Counterbore <NUM> may define a counterbore end wall <NUM> in the bridge <NUM>. The counterbore <NUM> thus accommodates and permits limited travel of the piston annular shoulder <NUM> therein, it being understood that counterbore end wall <NUM> provides an upper limit on the travel of the annular shoulder <NUM>, and thus the piston <NUM>, within the valve bridge <NUM>. Setscrew <NUM> may include external threads <NUM> which cooperate with counterbore internal threads <NUM> and may include a setscrew spring seat <NUM>. A lower end of spring <NUM> may be received in the spring seat <NUM> with a lower end of spring seated against a seat end wall <NUM>. A setscrew end wall <NUM> may define a lower limit for the travel of the piston annular shoulder <NUM>. Setscrew <NUM> may adjust the position of the piston lower limit, as well as the biasing force provided by compression spring <NUM> on the piston <NUM>.

<FIG>, <FIG> and <FIG> depict a hydraulic lash adjuster <NUM> in cooperating relationship with the spring piston arrangement described above, which operates as a lash adjuster loading component <NUM> in the valve bridge <NUM>. <FIG> is a detail view of the example cam illustrated in <FIG>, <FIG> and <FIG>. Lash adjuster <NUM> may have an expansion direction, which is the downward direction in the orientation of <FIG>, <FIG> and <FIG>, and a contraction or compression direction, which is the upward direction. As will be recognized, the piston <NUM> is biased in an upward direction within the valve bridge <NUM> by the compression spring <NUM>, thus tending to apply the spring force to the lash adjuster <NUM>. The stroke of the piston, however, is limited in both an upward direction, and this biasing force is only applied so long as the piston position is between the stroke limits.

<FIG> shows the piston <NUM> in a lash adjuster refill state, in which the piston is at its uppermost limit of travel. Specifically, the piston annular shoulder <NUM> engages the counterbore end wall <NUM> to limit upward travel of the piston <NUM>. With the piston <NUM> in this position, the biasing force of the compression spring <NUM> is isolated relative to the lash adjuster, and the lash adjuster may expand to take up any lash developed in the valvetrain. Such expansion will cause the lash adjuster to refill with hydraulic control fluid, which is typically circulating within the control system at a predetermined operating pressure. An example main event cam <NUM> is also depicted in <FIG> with the valvetrain components, such as a cam roller, rocker arm and push rods that may be present between main event cam <NUM> and the HLA <NUM> represented by dotted line <NUM>. Referring additionally to <FIG>, a base circle <NUM> of main event cam <NUM> is represented by a dotted line. The main event cam <NUM> may include a main event lifting surface <NUM>. Main event cam <NUM> also includes operational surfaces for facilitating the HLA refill and spring bridge preloading states of the lash adjuster loading component. An example HLA refill cam surface <NUM>, which may be a sub-base circle surface, may facilitate the lash adjuster loading component <NUM> assuming an HLA refill state, as will be further explained. The main event cam <NUM> may also include a lash adjuster loading component preload surface <NUM>, which may also be a sub-base circle surface, to facilitate the lash adjuster loading component <NUM> assuming a lash adjuster loading component preload state, as will also be further explained. As illustrated in <FIG>, the main event cam <NUM> is positioned rotationally such that the main event valvetrain components <NUM> interact with the HLA refill cam surface <NUM>. As further detailed in <FIG>, main event cam <NUM> may include first, second and third transition surfaces <NUM>, <NUM> and <NUM> between the main event surface <NUM>, HLA refill cam surface <NUM> and the lash adjuster loading component preload surface <NUM>. As will be recognized, cam <NUM> may rotate in a clockwise direction to facilitate the main event motion, HLA refill and lash adjuster loading component motions in the main event valvetrain as will be described further herein.

<FIG> shows the piston <NUM> in a preload state, with the preload cam surface <NUM> of the main event cam <NUM> interacting with the main event valvetrain components <NUM>. In this preload state, the piston annular shoulder <NUM>, and thus the piston <NUM> are positioned within the piston guiding bore <NUM> in between the upper limit (counterbore end wall <NUM>) and the lower limit (setscrew end wall <NUM>). Thus, the biasing force of the spring <NUM> is exerted against the lash adjuster <NUM>, keeping the lash adjuster in a preloaded state and preventing the lash adjuster <NUM> from over extending. This state of the piston <NUM> will typically be assumed during auxiliary events, such as braking, in which the auxiliary motion source <NUM> applies force to the bridge pin <NUM> through an auxiliary valvetrain (not fully shown in <FIG>, except for the bridge pin). When the bridge pin <NUM> displaces downward, the valve bridge <NUM> may tilt or pivot about the stem of valve <NUM>, it being understood that valve <NUM> may remain in the same position (i.e., closed) during an auxiliary event. Pivoting of the valve bridge <NUM> tends to move the center of the valve bridge down. The lash adjuster loading component - piston <NUM> - may thus apply the biasing force of the spring <NUM> and prevent the lash adjuster from over-extending.

<FIG> shows the piston <NUM> in a main event motion state, with a main event lift surface <NUM> of main event cam <NUM> interacting with the main event valvetrain components <NUM>. In this state, the piston annular shoulder <NUM> and thus the piston <NUM> are "bottomed out" at the lower extent of the stroke within the valve bridge <NUM>. Specifically, the piston annular shoulder <NUM> engages the setscrew end wall <NUM>. This state permits the transfer of high loads (through the piston <NUM> to the valve bridge <NUM>) typically associated with main event actuation of the engine valves <NUM> and <NUM>. During this state, because the lash adjuster <NUM> is under a high load due to the main event provided by the main event lift surface <NUM>, the lash adjuster <NUM> is maintained in a rigid state and otherwise unable to expand.

<FIG> is a graphical representation depicting example operational characteristics and sequencing of the valve actuation system of <FIG>. This figure represents main event and auxiliary event (braking) valve motion (lift) as a function of crankshaft angle. The main event valvetrain motion is shown by the dotted line. Auxiliary event valvetrain motion <NUM> is shown by the solid line and, it should be noted, coincides with the zero valve lift axis (x-axis) from about <NUM> degrees to about <NUM> degrees of crankshaft angle. In an embodiment, the main event and auxiliary event lifts are provided by two separate motion sources, e.g., a main event cam as illustrated in <FIG> and a separate and dedicated auxiliary cam via separate load paths and valvetrain components.

<FIG> shows two auxiliary valve events occurring in the auxiliary valvetrain resulting in lift of one or more valves (for example, valve <NUM> via bridge pin <NUM> in <FIG>). A brake gas recirculation (BGR) event <NUM> may occur from about <NUM> degrees to about <NUM> degrees of crankshaft angle. A compression release (CR) braking event <NUM> may occur from about <NUM> degrees of crankshaft angle to about <NUM> degrees of crankshaft angle (i.e., into the beginning of the next engine cycle). Those skilled in the art will appreciate that any of a number of other auxiliary events, as alternatives to or in addition to those illustrated in <FIG>, may be employed.

According to aspects of the disclosure, the lash adjuster loading component may provide controlled loading of the lash adjuster in the main event valvetrain. The lash adjuster loading component may provide for the occurrence of lash adjuster refill following main event lift and prior to the occurrence of auxiliary events <NUM> and <NUM>. More specifically, still referring to <FIG>, following the main lift event, beginning at about <NUM> degrees to about <NUM> degrees, the lash adjuster loading component transitions to a lash adjuster refill period or phase <NUM>, which extends from about <NUM> degrees to about <NUM> degrees. It will be recognized that the main event valvetrain motion <NUM> during this phase may be implemented by a sub-base circle surface on a main event cam, as depicted by the dotted line being in the negative valve lift region in <FIG>. It will further be recognized that the duration of the refill period may be controlled by appropriate configuration of the main event motion source, such as the main event cam surface, which may be provided with a refill cam surface (<NUM> in <FIG>) thereon to cause the lash adjuster loading component to assume a refill state as described above. Sub-base circle motion will typically cause lash to arise in the main event valvetrain. During this phase, the lash adjuster loading component will assume the lash adjuster refill state depicted in <FIG>, where stroke of the piston <NUM> is restrained by the upper limit (bore end wall <NUM>). In this state, the lash adjuster loading component will allow for refill of the lash adjuster following main event motion and prior to the auxiliary events.

According to further aspects of the disclosure, the lash adjuster loading component may ensure that over-extension or "jacking" of the lash adjuster during auxiliary events does not occur. With continued reference to <FIG>, prior to the onset of auxiliary events <NUM> and <NUM>, at about <NUM> degrees of crankshaft angle, the lash adjuster loading component may transition from the refill phase <NUM> to the preload period or phase <NUM>. It will be recognized that the main event valvetrain motion during this phase may be implemented by a sub-base circle surface on the main event cam, as depicted by the dotted line being in the negative valve lift region in <FIG>. However, the preload phase sub-base circle cam surface may typically be of higher elevation (radial distance) from the cam rotational axis than the refill cam surface, which causes lash adjuster loading component to be in a state where the piston <NUM> (<FIG>) is between the upper and lower stroke limits and thus permitted to apply the biasing force of compression spring <NUM> to the lash adjuster. The timing of the preload phase and the transition thereto may be achieved by appropriate control surfaces on the main event motion source, such as the main event cam, which may include a preload cam surface (<NUM> in <FIG>). During this phase, the lash adjuster loading component will be in the preload state depicted in <FIG> where the piston <NUM> maintains a biasing force against the lash adjuster, thus keeping the lash adjuster from over-extending. The preload state may continue beyond the <NUM>-degree crank angle an into the next engine power cycle as shown in <FIG> with the preload state continuing at <NUM>, beyond the termination of the CR event and for about <NUM> degrees of crank angle into the new engine cycle. As will be recognized from this disclosure, the duration of the preload state may extend for at least as long as the duration of any auxiliary events. While in the above example, two auxiliary events occur in succession and the duration of a single preload event extends across the duration of both auxiliary events, the present disclosure also contemplates the preload occurring at intermittent times in a given engine cycle to coincide with the separate respective durations of multiple auxiliary events. As will be recognized from this disclosure, the biasing force provided by the biasing component in the lash adjuster loading component, such as the compression spring <NUM> should be of suitable degree so as to counteract the any forces in the lash adjuster, such as force arising from hydraulic pressure in the lash adjuster.

As will be recognized from the present disclosure, timing and duration of the main event, HLA refill and preload states of the lash adjuster loading component may be controlled by appropriately configuring the aforementioned operational parameters, including the refill and preload cam surfaces on the main event cam, as well as configuring the stroke limits on the lash adjuster loading component. It will further be recognized that the piston stroke should be matched substantially to the translated distance between the HLA refill surface on the main event cam and the desired main event opening and closing position on the main event cam in order to ensure optimal refilling of the HLA and to achieve other benefits.

<FIG> is a schematic representation of a valve actuation system <NUM> relating to Type II valve architectures, according to aspects of the disclosure. In this example system, motion sources <NUM> may include a main event motion source <NUM> and an auxiliary motion source <NUM>. These motion sources may comprise a cam or other device for causing motion to be imparted through respective load paths, represented by the arrows and schematically-represented components (boxes) in <FIG>, and ultimately to engine valve <NUM>. The main event motion source <NUM> and auxiliary event motion source <NUM> may be separate sources, such as separate cams, including a main event cam and an auxiliary event (dedicated or braking) cam. Main event valvetrain components <NUM> transmit main event motion (and load) to engine valve <NUM>. A lash adjuster <NUM>, which may be hydraulic lash adjuster (HLA), may be disposed in an end pivot for a rocker and thus not be directly disposed in the main event load path. In other words, the HLA may be parallel to the main event load path and provide a reaction force to the main event load in order to take up lash between components in the main event valvetrain.

Auxiliary motion source <NUM> may transmit motion (and load) through an auxiliary event load path <NUM>, which may include an auxiliary event activation system <NUM> which may selectively transmit or absorb motion in the auxiliary event load path to facilitate the occurrence of an auxiliary event valve motion, such as engine braking, in engine valve <NUM>. One or more auxiliary motion valvetrain components <NUM> may be provided as a subset of the main event valvetrain components <NUM>. For example, the main event valvetrain components <NUM> may include an end pivot rocker, and the auxiliary motion valvetrain components <NUM> may include the same end pivot rocker.

According to an aspect of the disclosure, the main event valvetrain components <NUM> may include a lash adjuster loading component <NUM> disposed in the main event valvetrain. The lash adjuster loading component <NUM> interacts with components in the main event valvetrain to prevent over-extension or "jacking" of the lash adjuster <NUM>, which may be disposed in the main event valvetrain, in various embodiments as will be further described. More specifically, and as will be further detailed below, the lash adjuster loading component <NUM> may act on components in the valvetrain to cause a biasing force on the lash adjuster during periods of relatively low load, such as during auxiliary events or during transitions to or from auxiliary events. Further, the lash adjuster loading component <NUM> may permit refill of the lash adjuster <NUM> and will permit high loads to be transmitted to the main event valvetrain, such as loads present in the main event valvetrain during main event valve operation.

<FIG> is a schematic representation of a first example lash adjuster loading component arrangement <NUM> in a Type II valve architecture. Main event motion source may be a cam <NUM> which operates on an intermediate area of a rocker <NUM>, which may be of a type known as a finger follower, which is mounted on a pivot <NUM>. An auxiliary motion source <NUM>, which may be an auxiliary (dedicated) cam, separate from the main event cam <NUM>, may act on the rocker <NUM> through auxiliary valvetrain components illustrated as a dotted line in <FIG> for ease of illustration. While illustrated separate from the main event cam, auxiliary cam may be on the same camshaft as the main event cam and may operate on the same area (i.e., middle or intermediate region) of the rocker <NUM>. Rocker <NUM> operates on valve <NUM>. A lash adjuster <NUM> may cooperate with or be integrated with the pivot <NUM> so as to take up lash existing between the rocker and main event motion source <NUM>. A lash adjuster loading component <NUM> may be disposed in or cooperate with the rocker <NUM> to react against both the main event motion source <NUM> and the rocker <NUM> to maintain a load on the lash adjuster <NUM> and thereby prevent overextension thereof. As will be recognized, the internal components of the lash adjuster loading component <NUM> may provide a spring loaded, stroke limited function as described above, such that the lash adjuster <NUM> is maintained in a controlled position during main and auxiliary events. Further, main event cam <NUM> may be provided with the sub-base circle regions to implement the HLA refill and preloading functions as described above with reference to <FIG>, <FIG> and <FIG>.

<FIG> is a schematic representation of a second example lash adjuster loading component arrangement <NUM> in a Type II valvetrain architecture. Main event motion source may be a cam <NUM> which operates on an intermediate area of a rocker <NUM>, which may be of a type known as a finger follower, which is mounted on a pivot <NUM>. An auxiliary motion source <NUM>, which may be an auxiliary (dedicated) cam, separate from the main event cam <NUM>, may act on the rocker <NUM> through auxiliary valvetrain components illustrated as a dotted line in <FIG> for ease of illustration. While illustrated separate from the main event cam, auxiliary cam may be on the same camshaft as the main event cam and may operate on the same area (i.e., middle or intermediate region) of the rocker <NUM>. Rocker <NUM> operates on valve <NUM>. A lash adjuster <NUM> may cooperate with or be integrated with the pivot <NUM> so as to take up lash existing between the rocker and main event motion source <NUM>. A lash adjuster loading component <NUM> may be disposed adjacent to and/or may cooperate with lash adjuster <NUM> to react against a stationary part of the engine and the lash adjuster <NUM> to maintain a load on the lash adjuster <NUM> and thereby prevent overextension thereof. As will be recognized, the internal components of the lash adjuster loading component <NUM> may provide a spring loaded, stroke limited function as described above, such that the lash adjuster <NUM> is maintained in a controlled position during main and auxiliary events. As will be recognized, main event cam <NUM> may be provided with the sub-base circle regions to implement the HLA refill and preloading functions as described above with reference to <FIG> and <FIG>.

<FIG> is a schematic representation of a third example lash adjuster loading component arrangement <NUM> in a Type II valve architecture. Main event motion source may be a cam <NUM> which operates on an intermediate area of a rocker <NUM>, which may be of a type known as a finger follower, which is mounted on a pivot <NUM>. An auxiliary motion source <NUM>, which may be an auxiliary (dedicated) cam, separate from the main event cam <NUM>, may act on the rocker <NUM> through auxiliary valvetrain components illustrated as a dotted line in <FIG> for ease of illustration. While illustrated separate from the main event cam, auxiliary cam may be on the same camshaft as the main event cam and may operate on the same area (i.e., middle or intermediate region) of the rocker <NUM>. Rocker <NUM> operates on valve <NUM>. A lash adjuster <NUM> may cooperate with the pivot <NUM> so as to take up lash existing between the rocker and main event motion source <NUM>. A lash adjuster loading component <NUM> may be interposed between the lash adjuster <NUM> and the pivot <NUM> to maintain a load on the lash adjuster <NUM> and thereby prevent overextension thereof. As will be recognized, the internal components of the lash adjuster loading component <NUM> may provide a spring loaded, stroke limited function as described above, such that the lash adjuster <NUM> is maintained in a controlled position during main and auxiliary events. As will be recognized, main event cam <NUM> may be provided with the sub-base circle regions to implement the HLA refill and preloading functions as described above with reference to <FIG> and <FIG>.

<FIG> is a schematic representation of a fourth example lash adjuster loading component arrangement <NUM> in a Type II valve architecture. Main event motion source may be a cam <NUM> which operates on an intermediate area of a rocker <NUM>, which may be of a type known as a finger follower, which is mounted on a pivot <NUM>. An auxiliary motion source <NUM>, which may be an auxiliary (dedicated) cam, separate from the main event cam <NUM>, may act on the rocker <NUM> through auxiliary valvetrain components illustrated as a dotted line in <FIG> for ease of illustration. While illustrated separate from the main event cam, auxiliary cam may be on the same camshaft as the main event cam and may operate on the same area (i.e., middle or intermediate region) of the rocker <NUM>. Rocker <NUM> operates on valve <NUM>. A lash adjuster <NUM> may cooperate with or be integrated with the pivot <NUM> so as to take up lash existing between the rocker and main event motion source <NUM>. A sliding pin <NUM> may be disposed in the rocker <NUM>. A lash adjuster loading component <NUM> may be located in the rocker <NUM> at the rocker to sliding pin location to maintain a load on the lash adjuster <NUM> and thereby prevent overextension thereof. As will be recognized, the internal components of the lash adjuster loading component <NUM> may provide a spring loaded, stroke limited function as described above, such that the lash adjuster <NUM> is maintained in a controlled position during main and auxiliary events. As will be recognized, main event cam <NUM> may be provided with the sub-base circle regions to implement the HLA refill and preloading functions as described above with reference to <FIG> and <NUM>. The fixed stroke lash adjuster loading component <NUM> may bias the sliding pin <NUM> away from a rocker to pin contact surface and may provide a fixed stroke. This may allow the lash adjuster <NUM> to set lash with the rocker on base circle without compressing the lash adjuster loading element off of its stop. During auxiliary motion, the rocker arm is pressed against the lash adjuster loading element by a lift event on the main event cam profile. When the auxiliary motion source <NUM> opens the valve by acting on the sliding pin <NUM> the lash adjuster loading element is maintained in a compressed state relative to the rocker arm, and prevents the HLA from over extending. Pin <NUM> may be provided with biasing structure and stroke limiting structure such as that described above with regard to the spring piston in <FIG>, <FIG> and <FIG> and may be biased away from the valve end of rocker <NUM> a fixed stroke with a spring force sufficient to prevent extension of the HLA <NUM>. During the preloading period on the main event cam, this spring may be partially compressed so that when the pin <NUM> is moved downward by the <NUM> motion source, the spring <NUM> remains in a compressed state and prevents extension of the HLA <NUM>.

<FIG> is a schematic representation of a fifth example lash adjuster loading component arrangement <NUM> in a Type II valve architecture. Main event motion source may be a cam <NUM> which operates on an intermediate area of a rocker <NUM>, which may be of a type known as a finger follower, which is mounted on a pivot <NUM>. An auxiliary motion source <NUM>, which may be an auxiliary (dedicated) cam, separate from the main event cam <NUM>, may act on the rocker <NUM> through auxiliary valvetrain components illustrated as a dotted line in <FIG> for ease of illustration. While illustrated separate from the main event cam, auxiliary cam may be on the same camshaft as the main event cam and may operate on the same area (i.e., middle or intermediate region) of the rocker <NUM>. Rocker <NUM> operates on valve <NUM>. A lash adjuster <NUM> may cooperate with the pivot <NUM> so as to take up lash existing between the rocker and main event motion source <NUM>. Rocker <NUM> may include a pivot arm <NUM> mounted to a pivot point <NUM> thereon. A lash adjuster loading component <NUM> may be located at the rocker to pivot arm location and may include internal structure, similar to that described above with regard to the stroke-limited spring piston in the embodiment in <FIG>, <FIG> and <FIG>. Moreover, the stroke may be adjusted using a setscrew similar to that shown in those figures. The fixed stroke lash adjuster loading component <NUM> may bias the pivot arm <NUM>, which includes a contact surface with main event cam <NUM>. The pivot point <NUM> may operatively engage the rocker <NUM> and may also include a rolling element (not shown) that may have a fixed stroke allowing the HLA to refill when the pivot arm is in a fully extended state and the main event cam <NUM> is oriented such that the lash adjuster refill phase of the main event cam is operating on the pivot arm <NUM>. When the lash adjuster loading component <NUM> is in its fully compressed state, it allows the main event cam <NUM> to impart main event lift. When the lash adjuster loading component <NUM> is partially compressed during the "preloading period" of the main event cam, it allows motion from main event cam <NUM> to move the rocker body <NUM> downward, without losing pre-load on the HLA The lash adjuster loading component <NUM> may thus bias the pivot arm <NUM> away from the rocker and towards the cam a fixed stroke. This may allow the lash adjuster <NUM> to set lash with the rocker on base circle without compressing the lash adjuster loading component <NUM> off of its stop. During auxiliary motion, the rocker arm <NUM> is pressed against the lash adjuster loading component <NUM> by a lift event on the main event cam <NUM> acting on the pivot arm <NUM>. When the auxiliary motion source <NUM> opens the valve <NUM> by acting on the rocker <NUM> (with or without a sliding pin), the lash adjuster loading component <NUM> is maintained in a partially compressed state relative to the rocker arm, and prevents the lash adjuster <NUM> from over extending. Pivot arm <NUM> may contain a rolling element, flat surface, or curved contact surface. As will be recognized, main event cam <NUM> may be provided with the sub-base circle regions to implement the lash adjuster refill and preloading functions as described above with reference to <FIG>, <FIG> and <FIG>.

Claim 1:
An apparatus for actuating at least one of two or more engine valves in an internal combustion engine, comprising:
a main event motion source adapted to provide main event motion to the at least one engine valve;
a main event valvetrain for transmitting motion from the main event motion source to the valve through a first load path;
an auxiliary event motion source, separated from the main event motion source;
an auxiliary event valvetrain for transmitting motion from the auxiliary event motion source to one or more engine valves through a second load path;
a lash adjuster cooperating with the first load path and adapted to take up lash in the main event valvetrain of the at least one engine valve;
a lash adjuster loading component adapted to prevent over-extension of the lash adjuster.