JP7630019B2 - Valve actuation system with finger followers for lobe switching and single source lost motion - Google Patents

Description

CROSS-REFERENCE TO RELATED APPLICATIONS AND CLAIM OF PRIORITY This application is a continuation-in-part of U.S. non-provisional patent application Ser. No. 16/706,226, filed Dec. 6, 2019, entitled “FINGER FOLLOWER FOR LOBE SWITCHING AND SINGLE SOURCE LOST MOTION,” which is a continuation-in-part of U.S. Provisional Patent Application Ser. No. 62/776,450, filed Dec. 6, 2018, entitled “SWITCHING FINGER FOLLOWER,” and U.S. Provisional Patent Application Ser. No. 62/776,450, filed Dec. 6, 2018, entitled “SWITCHING FINGER FOLLOWER FOR SINGLE-SOURCE LOST MOTION,” which is a continuation-in-part of U.S. non-provisional patent application Ser. No. 62/776,450, filed Dec. 6, 2018, entitled “SWITCHING FINGER FOLLOWER FOR SINGLE-SOURCE LOST MOTION.” This application further claims priority to U.S. Provisional Patent Application No. 62/776,453, entitled "A SYSTEM FOR MOTION," the entire subject matter of which is incorporated herein by reference.

The present disclosure relates generally to systems and methods for actuating one or more engine valves in an internal combustion engine. More specifically, the present disclosure relates to systems and methods for varying the operational relationship between a source of motion, such as a cam, and one or more engine valves. Such systems and methods may include a rocker arm in the form of a finger follower that provides selective switching between lobes on a cam and/or operation as a lost motion device in an engine valve train.

Internal combustion engines are widely used in many applications and industries, including transportation and trucking. Valve actuation systems for use in internal combustion engines are well known in the art. Such systems typically include one or more intervening components that transfer valve actuation motion from a source of valve actuation motion (e.g., a cam) to one or more engine valves, which constitute a valve train. These valve actuation systems may facilitate a primarily positive power mode of operation in which the engine cylinders generate power from a combustion process. The intake and exhaust valve actuation motions associated with a standard combustion cycle are typically referred to as "main event" motions. Known engine valve actuation systems may provide modified main event valve motions, such as early or late intake valve closing. In addition to the main event motion, known engine valve actuation systems may facilitate auxiliary valve actuation motions or events that allow the internal combustion engine to operate in other modes or variations of the positive power generating mode (e.g., exhaust gas recirculation (EGR), early exhaust valve opening (EEVO), etc.), or engine braking, where the internal combustion engine operates without fuel, essentially as an air compressor, to create a retarding force that helps slow the vehicle.

In many engine systems, the valve train may include a finger follower, which is essentially a lever that pivots at one end with the other end of the lever in contact with the load, i.e., the engine valve. The finger follower typically includes a motion-receiving component disposed between the ends of the lever to receive valve-actuating motion from a motion source (such as a cam), which is then transferred to the engine valve via the load end of the lever.

Known variations of the above finger follower components include so-called "switchable" finger followers, examples of which are described in U.S. Pat. No. 7,546,822, the subject matter of which is incorporated herein by reference. As shown in FIG. 1, the finger follower comprises a body 11, which in this example pivots about a hydraulic lash adjuster (HLA) 2. The body 11 also supports lateral followers 30, which in this example can rotate about a shaft 17 and can engage a locking mechanism 40. As best shown in FIGS. 2 and 3, the body 11 further supports a central roller follower 20 positioned between the lateral followers 30. As further shown in FIGS. 2 and 3, the locking mechanism 40 can be controlled such that the locking bar 48 is maintained in an extended position, thereby contacting the tabs 38 of the lateral followers 30 (FIG. 2), or in a retracted position, thereby avoiding contact with the tabs 38 (FIG. 3). When the locking bar 48 contacts the tab 38 (i.e., in a locked or on state), the lateral follower 30 is prevented from rotating about the shaft 17 and is therefore maintained in a rigid relationship with the body 11. Thus, the motion applied to the lateral follower 30 by the lateral cam lobe 9 is transferred to the body and ultimately to the engine valve 3. In this case, the valve actuation motion provided by the central cam lobe 8 is not transferred to the central roller follower 20 with which it is aligned. On the other hand, when the locking bar 48 is retracted (i.e., in an unlocked or off state), the lateral follower 30 is free to rotate about the shaft 17 such that any motion applied by the lateral cam lobe 9 is absorbed by the lateral follower 30 and is not transferred by the body 11 to the engine valve 3. In this case, the valve actuation motion provided by the central cam lobe 8 is transferred to the central roller follower 20 and thereby to the engine valve 3.

Finger follower switching is most commonly found in light duty automotive applications. However, they are partially excluded from heavy to medium duty diesel or natural gas engine applications due to high load events and failures due to partially engaged switching mechanisms. Light duty applications are also known to fail due to similar partial engagement issues at much lower loads. Referring to the example of Figures 2 and 3, such partial engagement occurs when the locking bar 48 only partially overlaps the tab 38, i.e., at a location between the engagements shown in Figures 2 and 3. When such partial engagement occurs, contraction stresses between the moving parts of the locking mechanism can be significantly increased, leading to damage and/or failure of the locking mechanism.

Another disadvantage of prior art switched finger followers is that their use typically requires precise timing controls to prevent partial engagement of their actuating or locking components. This can require additional cost and complexity, especially in multi-cylinder engine environments. For example, in such environments it may be necessary to provide a designated control solenoid for each switched finger follower to eliminate the possibility of control circuit transients (i.e., lags in the hydraulic circuit) and ensure precise timing of actuating components relative to finger follower motion.

Switching finger followers can be applied to lost motion valve actuation systems. In such systems, a switching finger follower can be switched between a first position in which the full valve motion from a motion source, such as a cam, is transferred to the engine valve, and a second position in which only a portion of the full valve motion is transferred to the engine valve. An example of a single source lost motion lift profile described herein can be found in curve 502 of FIG. 5 of U.S. Pat. No. 9,347,383, the teachings of which are incorporated herein by this reference. However, due to the aforementioned disadvantages, prior art switching finger followers may have limited applicability to lost motion valve actuation systems.

It would therefore be advantageous to provide a system and method that addresses the above-mentioned deficiencies in the prior art and others.

In response to the aforementioned problems in the prior art, the present disclosure provides various embodiments of a switchable finger follower system with improved operating characteristics, as well as improved performance and durability.

The above-mentioned difficulties with conventional switchable finger followers can be overcome based on various embodiments disclosed herein. The advances in the art described herein are particularly advantageous in that they eliminate the possibility of partial engagement of the finger follower switchable mechanism actuation components. A related advantage is the elimination of variability in the locking or support position of the motion-receiving component on the switchable finger follower. The switchable finger follower configuration has a consistent contact geometry between the cooperating parts and a well-defined position of the switchable mechanism and thus a well-defined position of the finger follower lever and thus the motion-receiving component relative to the body. This leads to more accurate and reliable operation and control of the valve motion.

In addition, because the switched finger follower configurations disclosed herein are not sensitive to partial engagement of the switched mechanism, activation of the switched mechanism, they can be utilized at lower cost and complexity in multi-cylinder engine environments. Thus, the improved switched mechanisms and actuators eliminate the need for precise timing by control components. For example, in the case of hydraulically actuated switched mechanisms under the control of solenoids, the disclosed embodiments may eliminate the need for a controlled solenoid designated for each switched mechanism. Rather, the disclosed advances make it feasible for a single solenoid to actuate multiple cylinder switched mechanisms, thereby simplifying and reducing costs of the overall system.

Additionally, the embodiments described herein may be applicable to and used to improve single-source lost motion systems in which a single source of valve actuation motion (such as a cam) provides one or more low lift events in which some (or all) lift is lost, and one or more high lift events in which much (or all) of the lift from the cam lobe is transferred to the engine valve. Additionally, the embodiments described herein may be applicable to and used to improve lost motion valve actuation systems in which valve motion is lost entirely, such as may be required in systems utilizing cylinder deactivation.

The embodiments described herein may be particularly advantageous for achieving alternative valve movements such as late intake valve closing (LIVC), early exhaust valve opening (EEVO), and internal exhaust gas recirculation (IEGR) during braking.

According to one aspect of the disclosure, a finger follower system for use in an internal combustion engine valve train is provided, the finger follower system comprising: a follower body having a pivot end and a motion transmitting end; a lever adapted to pivot relative to the follower body; a motion receiving component having a motion receiving surface disposed between the follower body pivot end and the follower body motion transmitting end; and an adjustable support assembly including a movable latch for providing selective support to the lever, the adjustable support assembly being adapted to maintain the latch in a first latched position and a second latched position relative to the follower body. According to a further aspect, the adjustable support assembly is further adapted to allow the latch to move to the first position when the latch is not in the second position. In some applications, the adjustable support assembly may be further adapted to support the lever in two defined positions, providing engagement between the lever and the latch when the latch is in the first latched position and when the latch is in the second latched position. In other applications where the finger follower may facilitate complete loss of motion of the motion source, such as cylinder kill applications, the adjustable support assembly may be adapted to provide engagement between the latch and the lever when the latch is in a first latched position and to allow the lever to pivot freely from the latch (i.e., there is no engagement between the latch and the lever) when the latch is in a second latched position.

In one implementation, a finger follower with an adjustable support assembly may include an adjustable latch or lever engagement member adapted to move within the follower body to support the finger follower lever in at least one position. The lever engagement member or latch may cooperate with an actuation piston that may extend through a transverse bore in the lever engagement member. The piston may have first and second support surfaces that may provide two respective positively defined positions for the lever engagement member. In some applications, these two positions may correspond to positively defined support positions of the finger follower lever. In other applications, only one of the latch positions may support the lever, and the other position of the latch may correspond to the lever freely pivoting to a position not engaged with the latch (lower). The adjustable support assembly structure is adapted to not apply a load force to the actuation component when the lever engages the latch in a position other than the precisely defined position defined by the adjustable support assembly, thus avoiding damage to the actuation component and/or lever due to partial engagement.

In one implementation, the finger follower may include a lever engagement member or latch supported for movement relative to the finger follower body and having a substantially planar lever engagement member surface or latch surface that extends at an angle to the latch movement direction to engage an arcuate surface on the lever. The finger follower lever may include an arcuate surface adapted to be engaged by a planar lever engagement surface on the lever engagement member. Thus, the lever engagement member surface and the lever surface are adapted to maintain a substantially similar contact geometry when the lever and lever engagement member surface are engaged. In addition to eliminating the possibility of partial engagement, these aspects provide improved durability and operation.

According to another implementation, the finger follower assembly may be applied to a valve train environment of a single motion source lost motion engine. In some applications, the adjustable support assembly may support the finger follower lever in at least two positions, at least one of which may be a lost motion position. In other applications, the adjustable support assembly may support the finger follower lever in at least one position and allow the finger follower lever to pivot freely in another position such that motion of the motion source is not transmitted to the engine valve (as may be the case in a cylinder deactivation application). The biasing assembly may include at least one resilient element disposed between at least one spring support on the follower body and at least one spring support on the lever. A travel limiter on the body may limit upward movement of the lever. One or more precisely defined lever support positions may be implemented by interaction of the lever engagement member with the actuation piston to provide full or partial transmission (or full or partial loss) of valve motion through the lost motion finger follower.

According to another implementation, the finger follower may include an eccentric pivot mount that may provide adjustment of the position of the finger follower lever relative to the follower body.

Various finger follower assembly embodiments described herein may be incorporated into a valve actuation system. In one embodiment, the valve actuation system may include a first valve actuation motion source operably connected to a motion receiving component of the finger follower assembly, the first valve actuation motion source configured to provide a main event valve actuation motion, an auxiliary valve actuation motion, or a combination thereof. The first valve actuation motion source may be embodied by a dedicated cam assembly or a lost motion cam. Such auxiliary valve actuation motion may be an additional auxiliary valve actuation motion, such as an engine braking valve actuation motion, an internal exhaust gas recirculation valve actuation motion, or a combination thereof, or a main event modified auxiliary valve actuation motion, such as a late intake valve closing (LIVC) valve actuation motion, an early exhaust valve opening (EEVO) valve actuation motion, an early intake valve closing (EIVC) valve actuation motion, or a combination thereof. In various embodiments, the first valve actuation motion source may be embodied by a dedicated cam assembly or a lost motion cam. Additionally, in some embodiments, the valve actuation system may further include a second valve actuation motion source, and the follower body of the finger follower assembly may include a pair of arms having a lever disposed therebetween, and the lateral motion receiving component is disposed on each one of the pair of arms. In this embodiment, the second valve actuation motion source is configured to provide valve actuation motion to the lateral motion receiving component, and the valve actuation motion may include a main event valve actuation motion or a zero lift valve actuation motion.

Other aspects and advantages of the present disclosure will become apparent to those skilled in the art from the following detailed description, and the above aspects should not be considered as exhaustive or limiting. The above general description and the following detailed description are intended to provide examples of inventive aspects of the present disclosure and should not be construed in any way as limiting or restrictive of the scope defined in the appended claims.

The above and other attendant advantages and features of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings in which like reference numerals represent like elements throughout. It will be understood that the descriptions and embodiments are intended as illustrative examples according to aspects of the present disclosure and are not intended to be limiting on the scope of the present invention as set forth in the claims appended hereto. In the following description of the figures, all illustrations relate to features that are examples according to aspects of the present disclosure unless otherwise noted.
FIG. 1 is a perspective view of an example of a prior art switched finger follower and engine valve train environment that may be suitable for implementing aspects of the present disclosure. FIG. 2 is a cross-sectional view of the finger follower system of FIG. 1 in an “on” state. FIG. 2 is a cross-sectional view of the finger follower system of FIG. 1 in an “off” state. FIG. 1 is an assembled perspective view of an example finger follower assembly. FIG. 5 is an exploded perspective view of the example finger follower assembly of FIG. FIG. 13 is a detailed exploded perspective view of the finger follower adjustable support assembly. FIG. 5 is a side cross-sectional view of the finger follower assembly of FIG. 4 in a first state, which may be an "off" or "unlocked" state. FIG. 5 is a cross-sectional view in a lateral plane of the finger follower assembly of FIG. 4 in a first condition. FIG. 5 is a side cross-sectional view of the finger follower assembly of FIG. 4 in a second state, which may be an "on" or "locked" state. 5 is a cross-sectional view in a lateral plane of the finger follower assembly of FIG. 4 in a second condition. FIG. 13 is an assembled perspective view of a finger follower assembly according to a second embodiment in application as a lost motion device. FIG. 12 is an exploded perspective view of the lost motion finger follower assembly of FIG. FIG. 12 is a side cross-sectional view of the finger follower assembly of FIG. 11 in a first condition, which may result in some or all of the valve train motion being lost. FIG. 12 is a side cross-sectional view of the finger follower assembly of FIG. 11 in a second condition, in which some or all of the valve train motion may be transmitted. FIG. 13 is a side cross-sectional view of another embodiment of a finger follower assembly that allows the lever to pivot freely from the support assembly to facilitate complete loss of motion. FIG. 2 is a perspective view showing an eccentric swivel mount. FIG. 17 is a cross-sectional view of the pivot mount of FIG. 1A-1C are perspective views of example first and second sources of valve actuation motion in the form of dedicated cam assemblies; 1A-1C are cross-sectional views of example first and second valve actuation motion sources in the form of lost motion cams. FIG. 5 is a schematic top view of a first example of a valve actuation system based on the finger follower assembly of FIG. FIG. 12 is a schematic top view of a first example of a valve actuation system based on the finger follower assembly of FIG.

As used herein, phrases substantially similar to "at least one of A, B, or C" are intended to be construed disjunctively, i.e., requiring A or B or C, or any combination thereof, unless otherwise stated or implied by context.

4 is a perspective view of an exemplary assembled switched finger follower system 100 according to the present disclosure. FIG. 5 is an exploded perspective view of the same system. In particular, the switched finger follower may include a body or housing 400 arranged to support or house various other system components. The body 400 may extend longitudinally from a motion transmission or valve engagement end 410 adapted to interface or engage with one or more engine valves to a pivot end 420 adapted to interface or engage with a pivot shaft that may include an HLA. The body 400 may further include a pair of lateral longitudinally extending arms 402 and 404 defining a lever recess or pocket 406 therebetween. The arms 402 and 404 may include respective pivot pin receiving holes 403 and 405 at the valve engagement end 410 for securing a lever pivot pin 412 therein. A pair of lateral roller followers 430 and 434 may be secured to arms 402 and 404 via shafts 432 and 436, respectively. The lateral roller followers 430, 434 are configured to receive valve actuation motion from a complementary configured source of valve actuation motion, such as a source similar to the lateral cam lobes 9 shown in FIG. 1. Although the lateral followers are shown in roller form, it will be understood that the lateral followers may be implemented, for example, as flat follower contact areas extending from the body 400, and the disclosure need not be limited in this respect.

The body 400 may further support a lever 450 having a fixed end 452 that may be mounted in pivotable cooperation with the follower body 400 and extending longitudinally to a free end 460. The fixed end of the lever 450 may be fixed to a lever pivot pin 412 that is fixed to the arms 402, 404 of the body 400.

The lever 450 may have a shape that complements the recess or pocket 406 in the body 400, thereby providing nesting positioning within the body 400 and an overall compact finger follower configuration. The lever 450 may be formed as a precision single stamped metal (i.e., steel) component having a generally concave shape with a bottom wall 454 and an integral outer wall 456 extending from the bottom wall 454. A central portion of the lever 450 may support and accommodate a motion-receiving component cooperatively associated with the lever. The motion-receiving component may be a central roller follower 440 supported on a shaft 442 attached to the lever 450. Alternatively, the motion-receiving component cooperatively associated with the lever may be a contact surface directly on or attached to the lever and adapted to directly engage a motion source or a valve train component cooperating with the motion source. A recess or notch 458 may be formed in the bottom wall 454 to accommodate the central roller follower 440. The free end 460 of the lever may have an arcuate or otherwise curved lever end wall 461 having an arcuate or otherwise curved end surface 462 for selectively engaging an adjustable support assembly 500 integrated into the body 400, as described. The end wall 461 may be extended and contoured to have a smooth transition with the bottom wall 454. The lever end wall 461 may extend between the reduced lateral dimensions between opposing portions of the outer wall 456, which may provide additional stability and strength as well as reduce the likelihood of deformation of the end wall 461 during operation.

As will be appreciated, the central roller follower 440 may be configured to selectively receive valve actuation motion from a complementary configured source of valve actuation motion. For example, with reference to the engine environment described above with respect to FIG. 1, the central roller follower 440 may receive valve actuation motion from a central cam lobe, similar to cam lobe 8 of FIG. 1. As will be appreciated, in accordance with aspects of the present disclosure, the finger follower configuration described herein has the advantage of allowing for wider lateral and central follower dimensions compared to prior art systems, such as those described above with respect to FIGS. 1-3. This may allow for a wider cam surface, thus providing, for example, reduced contact stresses and wear between the cam and follower.

Additionally, with reference to FIGS. 6-10, the pivot end 420 of the finger follower body 400 may include a longitudinal bore 422 and a transverse bore 424 formed therein to accommodate components of the adjustable support assembly 500. The pivot end 420 may also include a recess or pocket 426 that interfaces with a suitable pivot assembly, such as a hydraulic lash adjuster having a post adapted to fit within the recess or pocket 426, and includes a hydraulic passage 428 (FIG. 8) for delivering pressurized hydraulic operating fluid (oil) to the finger follower, as will be further described.

The adjustable support assembly 500 may include a lever-engaging member or latch 510 and an actuation piston 530 cooperatively associated therewith. The lever-engaging member or latch 510 may be disposed within a longitudinal bore 422 that includes a cylindrical guide surface 423 for supporting and facilitating the sliding movement of the lever-engaging member or latch 510. The lever-engaging member or latch 510 may have a generally cylindrical shape including an outer cylindrical surface 512 and a substantially planar lever-engaging surface 514 that may extend at an angle relative to the axis of the lever-engaging member or latch 510. A lateral actuation piston receiving bore 516 may extend through the lever-engaging member or latch 510 for receiving and cooperating with the actuation piston 530. Additionally, the lever-engaging member or latch 510 may include a chamfered surface 518 (FIG. 5) on each side that transitions from the outer surface of the lever-engaging member or latch 510 to the piston receiving bore 516 to provide smooth interaction with the surface of the piston 530. It will also be appreciated that the chamfered surface 518 provides a reduction in the width of the lateral piston receiving bore 516, thereby eliminating the need to precisely align the lateral bore 516 with the piston 530 in order for the lateral bore 516 to engage the reduced diameter piston surface 532.

The actuation piston 530 may include a first support surface 532 adapted to engage and support the lever engagement member or latch 510 in a first position within the longitudinal bore 422, which may correspond to an unlocked, lowered, or retracted position of the lever 450 and central follower 440 relative to the body 400. The first support surface 532 may be a cylindrical surface having a first diameter. The actuation piston 530 may also include a second support surface 534 adapted to engage and support the lever engagement member or latch 510 in a second position within the longitudinal bore 422, which may correspond to an unlocked, raised, or deployed position of the lever 450 and central follower 440 relative to the body 400. The second bearing surface may be a cylindrical surface having a second diameter larger than the first diameter of the first bearing surface, substantially corresponding to the diameter of the lateral bore 424 of the body 400, and substantially corresponding to the diameter of the lateral actuation piston receiving bore 516. Disposed between the first bearing surface 532 and the second bearing surface 534 may be a transition surface 536 on the actuation piston 530, which may be generally tapered or conical in shape adapted to provide a smooth transition of the lever engagement member from the first bearing position to the second position during the locking operation of the actuation piston. The transition surface 536 may also facilitate the return of the actuation piston to the unlocked position when the actuation piston may be in an intermediate position between the fully retracted position and the fully deployed position in the lateral bore 424, as described in more detail below.

Operation of the adjustable support assembly 500 will now be described. Figures 7 and 8 show an exemplary switchable finger follower in an "unlocked" or off state with the lever 450 in a lower position relative to the body 400. The piston 530 is fully retracted within the lateral bore 424 and bottoms out against the end wall 425 of the lateral bore 424. A biasing device, such as a coil spring 533, may be disposed in the lateral bore 424 to engage a spring seat 539 and bias the piston toward a retracted position. This position aligns the first support surface 532 of the actuating piston 530 with the lateral piston receiving bore 516 of the lever engaging member or latch 510. The lever engaging member or latch 510 is retracted within the longitudinal bore such that the contact surface 514 is positioned to contact the lever end surface 462 along a first contact line, which may be a lower (i.e., below the axis) position on the surface 514 of the lever engaging member or latch 510. A spring retaining cap 535 can be attached to the body 400 (i.e., by press fit or threads) to retain the spring 533 and piston 530 within the lateral bore 424.

As shown in FIG. 8, the pivot receiving pocket 426 of the body 400 may be hydraulically connected to the lateral bore 424 via a hydraulic passage 428. When pressurized hydraulic fluid is not provided to the first lateral bore via the passage 428, a biasing element (not shown) may bias the piston 530 to the left as shown in FIG. 8. In this condition, the reduced diameter surface 532 of the piston 530 is aligned with the lever engaging member or latch 510. Thus, because the lever 450 is maintained in a lower position relative to the body 400, the central roller follower 440 is likewise maintained in a lower position, thereby establishing a lash between the central roller follower 440 and its corresponding source of valve actuation motion. This lash space causes a loss of valve actuation motion that would otherwise be applied to the central roller follower 440.

9 and 10, according to aspects of the present disclosure, the adjustable support assembly 500 can be actuated to support the lever 450 in a second position relative to the body 400. When pressurized hydraulic fluid is provided to the transverse bore 424, for example, via the passage 428 from a passage in the support HLA (not shown), the leftward bias applied to the piston 530 can be overcome such that the piston 530 is displaced to a point where the second support surface 536 is aligned with and supports the lever engagement member or latch 510. It will be appreciated from the present disclosure that other actuation techniques can be utilized instead of or in addition to the hydraulic fluid actuation system described by way of example herein. For example, pneumatic, electromagnetic, or purely mechanically interacting components can be utilized to provide the motive force for actuation of elements such as the described actuation piston or pin 530. The transition surface 536 can move the lever engagement member 510 from a first latched position to a second latched position (to the right in FIG. 9) as the piston 530 moves. 9, the lever end surface 462 may contact the slide member surface 514 at a relatively high point of the slide member contact surface 506 in this case. Thus, the lever 450 and central roller follower 440 are supported in a second position, in this case higher than the position corresponding to the first (retracted) position of the lever support member 510, and the central roller follower 440 may absorb any lash between the central roller follower 440 and its corresponding source of valve actuation motion. In this manner, valve actuation motion is applied to the central roller follower 440 and then transferred to the body 400 by contact between the lever 450 and the slide member 510 and further contact between the slide member 510 and the body 400. As will be appreciated from this disclosure and described in more detail in the context of a lost motion, cylinder deactivation application below, the first and second positions of the latch may define alternate states of the lever. More specifically, in the context of lost motion cylinder deactivation, a first position of the latch may be a "normal" operating state that facilitates lifting of the lever to a higher position relative to the follower body, and a second position of the latch may be a (retracted) "lost motion activated" operating state in which the lever does not engage the latch at all, but instead drops to a rest position relative to the follower body (i.e., facilitated by a stop that defines a lower limit of lever travel). In this state, the lever is in a lower position such that all valve motion that would otherwise be transmitted by the motion source is "lost" or can be absorbed by the finger follower system.

According to one aspect of the present disclosure, the adjustable support assembly 500 provides an advantage in distributing the load applied by the lever 450 (indicated by the thick black arrow in FIG. 9 ). More specifically, the vertical component of the load is distributed to the body 400 via the engagement of the outer surface 512 of the lever engagement member (also referred to herein as a latch) 510 with the inner surface of the longitudinal bore 422 (indicated by the vertical dashed arrow). The horizontal component of the load (indicated by the horizontal dashed arrow) is distributed to the piston 530 via the lever engagement member or latch 510. As will be appreciated, the angle of the lever engagement member surface 514 can be selected such that a majority of the load is distributed over a larger area of the guide surface of the longitudinal bore 422 and a smaller component of the load is borne by the actuation piston 530. It will further be appreciated that this load distribution occurs regardless of the position of the lever engagement member or latch 510 within the longitudinal bore 422. Moreover, due to the unique interaction of the lever end surface 462 with the surface 514 of the lever engagement member or latch 510, the possibility of partial engagement between these elements is effectively eliminated. In addition, by providing the lever end surface 462 with a substantially arcuate shape as shown, the contact stress between the lever engagement member 530 and the lever end surface 462 can be controlled, i.e., the size and shape of the contact area between the elements can be kept substantially constant in all operating conditions and positions of the lever relative to the body, i.e., regardless of the position at which the lever engagement member 530 engages the lever end surface 462. The lever engagement member surface 514 and the lever end surface 462 can be adapted to maintain a substantially similar contact shape at all positions of the lever that contact the lever engagement member surface 514. This improves durability and performance.

Still further, the unique interaction between the support surface of the piston 530 and the lever-engaging member or latch 510 provides the lever 450 with two well-defined switched support positions, the position of which, and therefore the corresponding movement of the actuating valve, can be very precisely controlled. Furthermore, the forces involved in the interaction between the piston 530 and the lever-engaging member 530 are reduced, thereby improving durability and performance consistency. A further related advantage of the exemplary adjustable support assembly according to aspects of the present disclosure is that it eliminates the possibility of excessive contact stresses between intermediate engagement positions between the lever-engaging member 530 and the lever 450. Such an intermediate position would be a position that is not either the first or second engagement positions as described above. As will be appreciated, when the piston 530 is in the retracted position, there is only one position that would be able to support the lever-engaging member 530. If the lever-engaging member is not in the first retracted position, no reaction force from the piston surface 532 is provided. Thus, if the lever-engaging member 530 may remain in the second position or not fully retract into the longitudinal bore 422 after the piston 530 retracts, no reaction force is provided when the load of the motion source is transferred to the lever 450 until the lever-engaging member 530 is in the first position. In this way, the system avoids applying a load force when the actuation component is not in the first or second position. In other words, the lever support assembly 500 is adapted to provide a support force to the lever only in the first or second position. That is, when the piston 1530 is in the first position and the lever-engaging member 1510 is in a position not engaged with the piston, the system allows the lever-engaging member 1510 to "float" in the longitudinal bore 422 and no reaction force is provided by the piston on the lever-engaging member until it is properly seated against the piston 1530. Thus, the adjustable support assembly is adapted to allow the lever to move to the first position when the lever is not in the first or second position. This arrangement eliminates damage to the supporting components and provides reliable and durable operation of the switchable finger follower.

11-13 show a second implementation embodying additional aspects according to the present disclosure. This implementation may be useful as a lost motion device in an engine environment using a single source of motion such as a cam to provide one or more low lift events, such as auxiliary events, where some lift may be lost, and one or more high lift events, such as combustion main events, where more (or all) of the lift from the cam lobes is transferred to the engine valves. An exemplary lost motion engine environment is described, for example, in U.S. Pat. No. 9,347,383, the subject matter of which is incorporated herein by reference in its entirety. As will be recognized, in such applications, a single cam profile having multiple lobes thereon is used in place of the combination of center 8 and lateral cam lobes 9 in the environment described above with respect to FIGS. 1-3.

11 is a perspective view of an exemplary assembled lost motion finger follower system 1000 according to one aspect of the present disclosure. FIG. 12 is an exploded perspective view of the same exemplary system. The switchable finger follower may have a general structure similar to the embodiment described above with respect to FIGS. 4-10. The structure and operation of the adjustable support assembly 1500, including the piston 1530, the lever engagement member 1510, and their interaction with the end surface 1462 are similar to the implementations described above and are understood to apply to this embodiment and need not be repeated. However, it will be recognized that the structure of the body 1400 and the lever 1450 may be modified to facilitate the functioning of the system in lost motion applications, as described below.

One modification may include the addition of a biasing assembly adapted to cooperate with the body 1400 and the lever 1450 to bias the lever 1450 toward a raised or deployed position away from the body 1400. The body 1400 may include a pair of laterally extending spring retaining flanges 1402 and 1404. Respective resilient elements (e.g., coil springs) 1422 and 1424 are retained between the flanges, thus biasing the lever 1450 and the central roller follower 1440 in a direction toward the source of motion (i.e., upward in FIGS. 11 and 12).

In another modification, the travel limiter 1425 may be disposed on the pivot end 1430 of the body 1400 and may be integrally formed therewith to limit the rotation of the lever 1450 away from the body 1400 by engaging the upper surface 1463 of the lever end wall 1461. Although the travel stop 1425 is shown as an integral component of the body 1400, it will be understood that the travel stop 1425 may be implemented as a separate component attached to the body 1400 or coupled thereto via another component. Additionally, the travel stop 1425 may include an adjustable feature such as an adjustment screw that threads into the illustrated limiter and is secured with a retaining nut to allow the upper limit of the travel of the lever 1450 to be adjusted.

As is known in the art, when hydraulic lash adjusters (HLAs) are incorporated into single-source lost motion valve trains, it is necessary to prevent the HLA from expanding during those operating conditions in which valve actuation motion is lost, i.e., to prevent the HLA from occupying the lash space purposefully provided to selectively lose valve actuation motion. In the illustrated embodiment, this is accomplished by the action of resilient elements 1422 and 1424, which are selected such that the force exerted by these elements on the lever 1450 is greater than the force exhibited by the associated HLA as it expands to absorb the available lash. In this manner, the resilient elements 1422, 1424 apply a sufficient load to the HLA to prevent undesired expansion of the HLA. On the other hand, if the force provided by the resilient elements 1422 and 1424 is applied to the HLA in an uncontrolled manner, it may cause excessive compression or bleed-down of the HLA. The travel limiting stop 1425 can thus limit the travel of the lever 1450 and, therefore, the force applied to the associated HLA by the resilient elements 1422, 1424. The distance of travel of the lever 1450 permitted by the travel stop 1425 is preferably controlled such that when the lever 1450 is against the travel stop 1425 and the HLA is operating to occupy lash space in the valve train, the lost motion travel is equal to the lost valve lift event. For example, if the travel stop 1425 allows an excessive stroke of the lever 1450, the lost motion operating condition will lose too much motion and the relatively high lift valve events (e.g., main events) will have excessive lash, resulting in undesirable lower valve lift and higher valve seating velocities. Conversely, if the travel stop 1425 allows for an insufficient stroke of the lever 1450, an insufficient amount of lash space will be established during the lost motion operation, and some of the valve actuation motion that would otherwise be lost will nevertheless be transmitted by the finger follower to the engine valve. This can lead to undesirable results such as altered valve lift and duration, and possibly additional unnecessary lift events when not desired. In embodiments in which the travel stop 1425 is attached to the body 1400 (rather than being integrally formed therewith), the travel stop 1425 may be adjustable so that the stroke of the lever 1450 can be precisely controlled.

Yet another modification, compared to the embodiment described above in connection with Figures 4-10, may include the elimination of the lateral roller followers since such elements may not be necessary in a single motion source environment where the finger follower system 1000 functions as a lost motion device.

In lost motion applications, the adjustable support assembly 1500 may provide at least two very precisely controlled positions of the lever 1450 relative to the finger follower body 1400, similar to the operation described above with respect to FIGS. 4-10. These two controlled positions may provide two levels of motion transmission from the motion source to the actuated valve. The first position may, for example, correspond to partial motion transmission and the second position may correspond to full motion transmission. As will be appreciated from this disclosure, the described embodiments may be adapted for lost motion applications where all valve motion that would otherwise be transmitted from the motion source (cam) is "lost" or absorbed by the finger follower system. In such cases, the lever may have only one precisely defined engagement position with the latch 510, and the lever may adopt a second position in which the latch does not engage the lever, or the latch engages the lever and supports the lever at a position low enough that no valve lift is transmitted from the motion source. The disengaged configuration of the lever may eliminate the need for precision in manufacturing to define at least the second disengaged position of the lever.

13, with the lever-engaging member 1510 in a retracted position and supported on the smaller diameter of the piston 1530, the lever surface 1462 contacts the lever-engaging member surface 1514 at a relatively low point. The lever 1450 and roller follower 1440 are maintained at a lower position relative to the body 1400, thereby establishing lash between the roller follower 1440 and its corresponding source of valve actuation motion. This lash space causes the relatively low-lift valve actuation motion that would otherwise be applied to the central roller follower 1440 to be lost, but the relatively high-lift valve actuation motion is still received by the roller follower 1440 and transmitted to the finger follower body 1400 and ultimately to the engaged valve.

Additionally, with reference to FIG. 14, with the piston 1530 hydraulically actuated to overcome the spring bias, the piston may move to a point where its full diameter completely occupies the lateral bore of the lever engagement member 1510. Thus, the lever engagement member 1510 is in a fully deployed position, and the lever 1450 and follower 1440 are maintained in a relatively high position to absorb any lash between the follower 1440 and the source of valve actuation motion. In this state, relatively low lift valve actuation motions, as well as relatively high lift valve actuation motions, are applied to the roller follower 1440 and transmitted to the finger follower body 1400 and ultimately to the valve engaged thereby.

In addition to the precisely controlled position of the lever 1450 relative to the finger follower body 1400 described above, and the precise control as a result of the lost motion capability provided by the finger follower system, the above configuration also provides the advantage of eliminating intermediate positioning of the lever 1450, and thus intermediate transmission of valve motion. As described in detail above with respect to the operation of the adjustable support assembly 500 in the embodiment of Figures 4-10, the adjustable support assembly 1500 can be adapted to provide support at two defined positions for interaction between the piston 1530 and the lever engagement member 1510.

FIG. 15 illustrates another embodiment according to aspects of the present disclosure that may be useful in applications such as cylinder deactivation applications where complete loss of valve motion may be facilitated. In this embodiment, lower lever positioning is facilitated by an adjustable support assembly 2500 that allows the lever to pivot freely from the latch 2510 and thus to a (second) lever position that is lower relative to the follower body than that provided in the previously described embodiment. FIG. 15 illustrates the latch 2510 in a first position, with the larger diameter surface 2534 engaging the lateral bore of the latch 2510 and supporting it in its shown extended position, and the latch surface 2514 engaging the lever surface 2462, thereby holding the lever 2450 in the shown (first) position. This position may correspond to a "de-energized" state of the actuator piston 2530 (i.e., a "normally latched" lever position), with the lever 2450 positioned to transmit normal valve motion. According to aspects of this embodiment, when the piston 2530 is energized, the smaller diameter surface 2532 aligns with the lateral hole in the latch, allowing the latch 2510 to be retracted (i.e., move up and to the left in FIG. 15). This position of the latch 2510 allows the lever 2450 to pivot to a lower position where it is completely free and does not engage the latch 2510. Thus, this configuration may be useful in applications such as cylinder deactivation applications where such a low lever position is required to completely eliminate valve movement.

16 and 17 show details of a pivot pin 1412 that can be used in any of the implementations described above. As shown, the pivot member 1412 includes an eccentric shaft 920 formed therein. In particular, the axis of the shaft 920 is not aligned with the axis of the pivot member 912. In addition, the eccentric shaft 920 is provided with a threaded mounting hole 922. As best shown in FIG. 17, the pivot member 912 can be supported by a body 400 with a lever 408 mounted for rotation on the eccentric shaft 920. A suitable fastener 1002 can be used to secure the assembly of the pivot member 912, lever 408, and body 400. By selectively rotating the pivot member 912, the position of the eccentric shaft 922 can be moved relative to the body 1400 such that the pivot end of the lever 408 is similarly shifted upwardly or downwardly relative to the body 1400. In this manner, the pivot member 912 can be used to adjust or control the position of the lever 1450 to operate with different cam profiles to establish various lash settings or to allow for less precise and less expensive manufacturing processes.

As will be appreciated, various geometric variations in the shapes of the interacting surfaces of the lever-engaging member or latch 510, actuation piston 530, lever end surface 462, and other surfaces described herein may be provided without departing from the spirit and scope of the present invention. For example, the lever-engaging member or latch 510 may comprise a curved or arcuate surface and the lever 450 may comprise a flat surface. Additionally, while described as cylindrical elements, the piston and lever-engaging member may comprise square or rectangular or other cross-sectional shapes.

As a further example, although the lever-engaging member 530 has been shown and described as operating under the control of a mechanical interaction with the piston 530, which in turn is hydraulically controlled, it will be understood that other configurations for controlling the lever-engaging member may be employed. For example, the lever-engaging member 530 may be biased to its unlocked or off state by a resilient element, and a hydraulic passageway may be connected to the bore in which the lever-engaging member 530 resides, such that application of hydraulic fluid to the passageway extends the lever-engaging member 530 to its locked or on state, while a locked amount of hydraulic fluid in the bore of the slide member maintains the lever-engaging member 530 in its extended position. As another example, although the lever contact surface 462 is shown as having an arcuate shape, this is not a requirement, and other surface configurations, e.g., angled, semicircular, etc., may similarly be employed. Still further, it will be understood that the configuration of the body 400 and lever 450 may be reversed, i.e., a central body may be provided with an outer movable arm, which may be placed in an unlocked/off state or a locked/on state using one or more similarly configured slide members as described above.

Examples of embodiments of valve actuation systems incorporating finger follower assemblies as described herein are further illustrated with reference to FIGS. 18-23. In particular, a valve actuation system according to the present disclosure may include a first source of valve actuation motion in conjunction with a finger follower assembly as described herein, the first source of valve actuation motion configured to provide a main event valve actuation motion, an auxiliary valve actuation motion, a zero lift valve actuation motion, or a combination thereof.

As discussed above, a main event valve actuation is a valve actuation typically applied to the intake valves and/or exhaust valves during the combustion of fuel to generate a positive power output by one or more cylinders of an internal combustion engine. As further discussed above, an auxiliary valve actuation is a valve actuation that allows one or more cylinders of an internal combustion engine to operate in an otherwise non-positive power generating mode of operation or in a variation of a positive power generating mode. An auxiliary valve actuation can be further classified as an additional auxiliary valve actuation or a main event modified auxiliary valve actuation. An additional auxiliary valve actuation is a valve actuation that is performed in addition to a main event valve actuation and does not otherwise modify the lift profile of such main event valve actuation. Non-limiting examples of such additional auxiliary valve actuation include engine brake (e.g., compression-release) valve actuation or internal exhaust gas recirculation (IEGR) valve actuation. On the other hand, a main event modified auxiliary valve actuation is a valve actuation that results in some modification of the lift profile that would otherwise occur during the main event valve actuation. Non-limiting examples of such main event corrective valving include late intake valve closing (LIVC) valving, early exhaust valve opening (EEVO) valving, or early intake valve closing (EIVC) valving. In the case of LIVC and EEVO, such auxiliary valving may be included along with the standard main event valving only on demand, i.e., when the main event valving is the default valving. On the other hand, EIVC operation may be achieved when the main event valving is a narrowed (i.e., early closing) version of the standard main event valving, such that incorporation of the EIVC auxiliary valving corrects the narrowed main event by extending its closing timing.

As will be appreciated by those skilled in the art, the valve actuation motion source can be implemented in a variety of forms, provided that it provides the required valve actuation motion. FIGS. 18 and 19 show various embodiments of the first and second valve actuation motion sources in the form of cams. In particular, FIG. 18 shows an example of a dedicated cam assembly 1800 comprising a first valve actuation motion source 1804 and a second valve actuation motion source 1806 in one embodiment. That is, the dedicated cam assembly comprises more than one cam for providing main and auxiliary valve actuation motions or a combination thereof. Through the first and second valve actuation motion sources 1804, 1806, the dedicated cam assembly 1800 can provide additional and/or main event modified auxiliary valve actuation motions in conjunction with the main event valve actuation motion. As a result, when combined with the finger follower assembly described in FIG. 4, as described in more detail below, the dedicated cam assembly 1800 can provide a valve actuation assembly that can provide additional and/or main event modified auxiliary valve actuation motions in conjunction with the main event valve actuation motion.

FIG. 19 shows an example of a lost motion cam 1900 in which a first valve actuation motion source 1904 is combined with a second valve actuation motion source 1906 in a single cam. As known in the art, such a lost motion cam 1900 is defined by a base circle 1908 and a sub-base circle 1910. During an operating mode in which only valve actuation motion from the first valve actuation motion source 1904 is transferred (typically a main event only operating mode), the valve train components are operated in a retreated/lost motion manner such that only valve actuation profiles at or above the base circle 1908 are provided by the valve train to the corresponding engine valves, i.e., any valve actuation profile below the base circle 1908 is lost. On the other hand, during an operating mode in which valve actuation motion from both the first and second valve actuation motion sources 1904 is transferred (typically an auxiliary operating mode), the valve train components are operated in an extended/non-lost motion manner such that all valve actuation profiles above the sub-base circle 1908 are provided by the valve train to the corresponding engine valves, i.e., no valve actuation profile is lost. Once again, via the first and second valve actuation motion sources 1904, 1906, the lost motion cam 1900 can provide only additional and/or main event modified auxiliary valve actuation motion in conjunction with the main event valve actuation motion. As a result, when combined with the finger follower assembly described in FIG. 11 as described in more detail below, the lost motion cam 1900 can provide a valve actuation assembly that can provide additional and/or auxiliary valve actuation motion in conjunction with the main event valve actuation motion.

20, a valve actuation system 2000 is shown that includes a dedicated cam assembly 1800 in combination with a finger follower assembly 2002 according to the embodiment of FIG. 4 described above. In this embodiment, a first valve actuation motion source 1804 is operably connected to a lateral motion receiving component, i.e., a pair of lateral roller followers 430, 434, while a secondary valve actuation motion source 1806 is operably connected to a motion receiving component or central roller follower 440. In this embodiment, the first valve actuation motion source 1804 may be configured to provide a main event valve actuation motion, while the second valve actuation motion source 1806 may be configured to provide additional and/or main event modified auxiliary valve actuation motion, as described above. In this manner, the latch 510 may be controlled as described above to prevent the valve actuation motion provided by the second valve actuation motion source 1806 from being lost, thereby allowing only the valve actuation motion provided by the first valve actuation motion source 1804 to be transmitted by the finger follower assembly 2002 to the corresponding engine valve (not shown). On the other hand, the latch 510 may be controlled as described above to prevent the valve actuation motion provided by the second valve actuation motion source 1806 from being lost, thereby allowing the valve actuation motion provided by both the first and second valve actuation motion sources 1804, 1806 to be transmitted by the finger follower assembly 2002 to the corresponding engine valve.

In a variation of the embodiment shown in FIG. 20, the configuration of the first and second valve actuation motion sources 1804, 1806 may be modified to support cylinder deactivation using the finger follower assembly 2002 of FIG. 4. In this variation, the first valve actuation motion source 1804 is configured to provide a regressive or zero-lift valve actuation motion. For example, in the context of a cam, such zero-lift valve actuation motion would occur when the cam implementing the first valve actuation motion source does not include a lobe that extends above the base circle of the cam, i.e., only the base circle is provided. Additionally, in this variation, the second valve actuation motion source is configured to provide a main event valve actuation motion. In this configuration, when the latch 510 is controlled as described above such that the valve actuation motion provided by the second valve actuation motion source 1806 is lost, only the valve actuation motion provided by the first valve actuation motion source 1804 is transmitted to the corresponding engine valve by the finger follower assembly 2002. However, because the first valve actuation source 1804 is configured to provide only zero-lift valve actuation motion, the corresponding engine valve is not opened, thereby implementing a cylinder deactivation mode. On the other hand, when the latch 510 is controlled as described above such that the valve actuation motion provided by the second valve actuation motion source 1806 is not lost, the valve actuation motion provided by both the first and second valve actuation motion sources 1804, 1806 is transferred to the corresponding engine valve by the finger follower assembly 2002. In this case, the main event valve actuation motion provided by the second valve actuation motion source 1806 is combined with the zero-lift valve actuation motion provided by the first valve actuation motion source 1804, with the net effect that only the main event valve actuation motion is transferred to the engine valve.

21, a valve actuation system 2100 is shown that includes a lost motion cam 1900 in combination with a finger follower assembly 2102 according to the embodiment of FIG. 11 described above. In this embodiment, both the first and second valve actuation motion sources 1904, 1906 are operatively connected to the motion receiving component, i.e., the central roller follower 440. In this embodiment, the first valve actuation motion source 1904 may be configured to provide a main event valve actuation motion, while the second valve actuation motion source 1906 may be configured to provide additional and/or main event modified auxiliary valve actuation motion, as described above. In this manner, the latch 510 may be controlled as described above to allow the valve actuation motion provided by the second valve actuation motion source 1906 to be lost, thereby allowing only the valve actuation motion provided by the first valve actuation motion source 1904 to be transmitted by the finger follower assembly 2102 to the corresponding engine valve (not shown). Meanwhile, the latch 510 can be controlled as described above so that the valve actuation motion provided by the second valve actuation motion source 1906 is not lost, thereby allowing the valve actuation motion provided by both the first and second valve actuation motion sources 1904, 1906 to be transmitted to the corresponding engine valves by the finger follower assembly 2102.

As previously discussed, it will be appreciated that the finger follower assembly 2102 may also be operated such that all valve actuation motion (from both the first and second sources of valve actuation motion 1904, 1906) is lost, thereby facilitating cylinder deactivation of a given cylinder, for example.

While the present implementation has been described with reference to certain exemplary embodiments, it will be apparent that various modifications and changes can be made to these embodiments without departing from the broader spirit and scope of the invention as set forth in the claims. The specification and drawings are therefore to be regarded in an illustrative rather than a restrictive sense.

Claims (36)

1. A valve actuation system for use in an internal combustion engine valve train, the valve actuation system comprising:
a first valve actuation motion source; and a finger follower assembly, the finger follower assembly comprising:
a follower body having a pivot end and a motion transmitting end;
a lever adapted to pivot relative to said follower body;
a motion receiving component having a motion receiving surface disposed between the pivot end and the motion transmitting end, the motion receiving surface being operatively connected to the first valve actuation motion source;
an adjustable support assembly including a movable latch configured to provide selective support to the lever, the adjustable support assembly adapted to alternately maintain the latch in a first latched position and a second latched position relative to the follower body, the adjustable support assembly further including an actuation piston extending into a piston receiving bore of the latch and cooperating with the latch to define the first latched position and the second latched position;
A valve actuation system, wherein the first valve actuation motion source is configured to provide main event valve actuation motion, auxiliary valve actuation motion, zero lift valve actuation motion, or a combination thereof. The valve actuation system of claim 1, wherein the actuation piston includes a transition surface that enables the lever to move the latch to the first latched position when the transition surface is engaged by the latch. The valve actuation system of claim 1, wherein the adjustable support assembly is further adapted to provide an engagement between the lever and the latch when the latch is in the first latched position. The valve actuation system of claim 1, wherein the adjustable support assembly is further adapted to allow the lever to pivot to a lever position in which the lever is not engaged with the latch. The valve actuation system of claim 1, wherein the adjustable support assembly is further adapted to provide an engagement between the lever and the latch when the latch is in the second position. The valve actuation system of claim 1, wherein the actuation piston is adapted to provide a supportive reaction force to the latch when the latch is in the first latched position and when the latch is in the second latched position, and the actuation piston includes a transition surface adapted to allow the latch and actuation piston to move when the latch is between the first latched position and the second latched position. The valve actuation system of claim 1, wherein the follower body further includes a guide hole, and the latch is positioned to move within the guide hole. The valve actuation system of claim 1, wherein the follower body further includes an actuation fluid passage in fluid communication with the actuation piston. The valve actuation system of claim 1, wherein the actuation piston includes a first actuation piston surface adapted to support the latch in the first latched position and a second actuation piston surface adapted to support the latch in the second latched position. The valve actuation system of claim 9, wherein the first actuation piston surface extends a first distance from an axis of the actuation piston, and the second actuation piston surface extends a second distance from the axis of the actuation piston. The valve actuation system of claim 9, wherein the second actuation piston surface corresponds to the piston receiving bore. The valve actuation system of claim 9, wherein the actuation piston further includes a transition surface between the first actuation piston surface and the second actuation piston surface, the transition surface adapted to move the latch from the first latched position to the second latched position when the actuation piston is actuated. The valve actuation system of claim 1, wherein the lever includes a lever surface adapted to engage a latch surface of the latch, and at least one of the latch surface and the lever surface includes an arcuate surface. The valve actuation system of claim 1, wherein the lever includes a lever surface adapted to engage a latch surface of the latch, the latch surface and the lever surface adapted to maintain a substantially similar contact geometry when the latch surface and the lever surface are engaged in all positions of the lever. The valve actuation system of claim 1, wherein the latch is adapted to move relative to the follower body in a latch motion direction, and the latch includes a substantially planar latch surface that extends at a latch surface angle relative to the latch motion direction. The valve actuation system of claim 15, wherein the latch is adapted to move against a guide surface on the follower body, and the latch surface angle is such that a majority of the load force applied to the latch by the lever is applied to the guide surface. The valve actuation system of claim 1, wherein the motion receiving component is a cam follower roller that cooperates with the lever. The valve actuation system of claim 1, wherein the motion receiving surface is integrally formed on the lever. The valve actuation system of claim 1, wherein the lever is coupled to the follower body via an eccentric mounting element that allows the position of the pivot end of the lever to be adjusted relative to the follower body. The valve actuation system of claim 1, further comprising a lever biasing assembly for biasing the lever toward the first source of valve actuation motion. The valve actuation system of claim 20, further comprising a movement limiter for limiting movement of the lever relative to the follower body. 21. The valve actuation system of claim 20, further comprising a hydraulic lash adjuster in the valve train, the hydraulic lash adjuster having a lash adjustment force, and the lever biasing assembly providing a biasing force to the lever that is greater than the lash adjustment force. 21. The valve actuation system of claim 20, wherein the lever biasing assembly comprises at least one resilient element disposed between the lever and the follower body. 21. The valve actuation system of claim 20, further comprising at least one follower body spring support disposed on the follower body and at least one lever spring support disposed on the lever, the lever biasing assembly including at least one respective resilient element disposed between the follower body spring support and the lever spring support. 22. The valve actuation system of claim 21, wherein the position of the travel limiter relative to the follower body is adapted to provide adjustment of the upper limit of the travel of the lever relative to the follower body. The valve actuation system of claim 1, wherein the auxiliary valve actuation motion provided by the first source of valve actuation motion includes at least one additional auxiliary valve actuation motion. 27. The valve actuation system of claim 26, wherein the at least one additional auxiliary valve actuation movement includes at least one of an engine brake valve actuation movement or an internal exhaust gas recirculation valve actuation movement. The valve actuation system of claim 1, wherein the auxiliary valve actuation motion provided by the first valve actuation motion source includes at least one primary event modified auxiliary valve actuation motion. 29. The valve actuation system of claim 28, wherein the at least one primary event modified auxiliary valve actuation comprises at least one of a late intake valve closing valve actuation, an early exhaust valve opening valve actuation, or an early intake valve closing valve actuation. The valve actuation system of claim 1, wherein the first source of valve actuation motion is a dedicated cam assembly. The valve actuation system of claim 1, wherein the first valve actuation motion source is a lost motion cam. a second valve actuation motion source;
the follower body comprising a pair of arms having the lever disposed therebetween and a pair of lateral motion receiving components disposed on each of the pair of arms, the motion receiving surfaces being operatively connected to the first valve actuation motion source;
The valve actuation system of claim 1 , wherein the second valve actuation motion source is configured to provide main event valve actuation motion or auxiliary valve actuation motion to the lateral motion receiving component. 33. The valve actuation system of claim 32, wherein the auxiliary valve actuation motion provided by the second source of valve actuation motion includes at least one additional auxiliary valve actuation motion. 34. The valve actuation system of claim 33, wherein the at least one additional auxiliary valve actuation movement includes at least one of an engine brake valve actuation movement or an internal exhaust gas recirculation valve actuation movement. 33. The valve actuation system of claim 32, wherein the auxiliary valve actuation motion provided by the second valve actuation motion source includes at least one primary event modified auxiliary valve actuation motion. 36. The valve actuation system of claim 35, wherein the at least one primary event modified auxiliary valve actuation comprises at least one of a late intake valve closing valve actuation, an early exhaust valve opening valve actuation, or an early intake valve closing valve actuation.