2-stage valve closing rocker assembly

Abstract

The valve actuation system comprises a rocker for transmitting motion to an engine valve, a motion source arranged to impart motion to the rocker, a rocker stop assembly configured to operate in an active mode and an inactive mode, wherein in the active mode the rocker stop assembly maintains the rocker at a position corresponding to a partial valve lift, and in the inactive mode the rocker stop assembly enables moving the rocker to a position corresponding to a fully closed valve position, and a rocker stop reset assembly for resetting the rocker stop assembly to the inactive mode following a main event peak lift to achieve late valve closing. A damper assembly may interact with the rocker stop assembly to provide a smooth transition of rocker and valve motion to the late intake valve closing dwell. A valve catch assembly may control the settling speed of at least one valve.

Description

Background Technology

[0001] Technology field

[0002] The present disclosure relates to an internal combustion engine valve actuation system comprising a system for providing late intake valve closure (LIVC). The present disclosure also relates to a valve closure timing system and a valve catch system. The present disclosure also relates to a method associated with such a system.

[0003] Engine valve actuation systems providing LIVC in internal combustion engines are known to offer improved fuel economy and lower operating costs by changing the engine's effective compression ratio based on operating conditions. LIVC has been shown to slightly improve fuel economy under specific operating conditions.

[0004] Such a system can also be advantageous by providing thermal management to the engine aftertreatment system by changing the engine's effective compression ratio based on different operating conditions. LIVC has been shown to increase temperature based on operating conditions.

[0005] Background Technology

[0006] There are loss motion LIVC systems that use a collapse loss motion piston in the rocker arm. However, one limitation of such systems is that the peak main event intake valve lift needs to be modified, which can affect operating conditions (activated LIVC vs. deactivated LIVC). Therefore, it would be advantageous to provide a loss motion LIVC system that does not require modification of the peak intake valve main event lift.

[0007] Many known variable valve actuation (VVA) systems are designed to achieve the LIVC Miller cycle. For example, a loss motion VVA system is known in which a single motion source (VVA cam profile) is configured for LIVC. In this case, the single motion source must add lift to the closing portion of the normal cam profile to achieve LIVC and cancel (or lose) this LIVC lift to provide normal closing timing (i.e., closing without LIVC action). Examples of such systems can be found in U.S. Patent No. 6,883,492 (master-slave piston arrangement in an overhead housing), U.S. Patent No. 7,484,483 (master-slave piston arrangement in a tappet between rocker and valve bridge), U.S. Patent No. 5,829,397 (master-slave piston arrangement in a tappet between push-tube and rocker), U.S. Patent No. 7,905,208 (collapsing valve bridge), and U.S. Patent No. 6,510,824 (collapsing rocker pivot). However, such systems may have drawbacks regarding performance and cold start. Furthermore, the cost and complexity of such systems often make their use impractical or prohibitive. Therefore, it would be advantageous to provide a LIVC system that is less expensive and less complex than conventional VVA systems.

[0008] Some stationary power systems use fixed Miller cycles because such systems result in a high percentage of time under specific operating conditions where Miller timing is required. However, since such systems lack the ability to switch between LIVC and normal closing timing, they experience a performance impact under certain operating conditions.

[0009] U.S. Patent Application Publication No. 20030213443 (Fig. 1) discloses a system having a separate overhead housing designed to achieve a LIVC Miller cycle by fixing the intake rocker in an open position. However, the use of the electronically controlled high-speed solenoid valve disclosed herein makes this system expensive, and software or high-speed solenoid valve failure can lead to valve-piston contact and engine damage. Therefore, a LIVC solution based on a mechanical reset system would improve reliability, reduce the risk of valve-piston contact, and reduce costs.

[0010] U.S. Patent No. 7,156,062 (Fig. 2) describes a system having an intermediate loss motion actuator and a self-adjusting valve catch (SAVC) acting on a valve train element (e.g., a rocker arm) independently of a loss motion system. U.S. Patent No. 8,453,613 (Fig. 3) describes a system having an improved SAVC acting on a valve train element independently of a loss motion system.

[0011] The present disclosure describes embodiments of valve actuation systems that may include a LIVC system that overcomes many, but not all, of the aforementioned disadvantages of systems of the prior art. As mentioned above, in the case of lossy motion LIVC systems, the peak main event lift is often modified. In the case of auxiliary rocker-based LIVC systems (e.g., U.S. Patent No. 7,392,772 and U.S. Patent No. 11,131,222), a separate cam lobe is required, and there is a handoff that needs to be managed between the main event and the auxiliary LIVC event. One advantage of the embodiments described in the present disclosure is that all lift associated with intake valve motion including LIVC capability can be derived from a single cam lobe. Thus, the need for a separate cam lobe and handoff of the prior art is eliminated.

[0012] To achieve LIVC, embodiments of the present disclosure may provide a valve actuation system that utilizes a rocker stop to maintain the intake rocker arm and valve open position following a peak main event lift (typically between 3 mm and full valve lift) to achieve a subsequent closing event. The present disclosure also describes different systems and methods used to achieve a predetermined closing crank angle timing for the intake valve, such as a hydraulic reset. Additionally, different systems and methods for controlling the settling speed using a valve catch or a sub-base round cam closing ramp are disclosed herein.

[0013] In the disclosed embodiment, the rocker stop is a hydraulic actuator piston that keeps the rocker and valve open for a specific period of crank angle degree before the occurrence of a closing event. In one embodiment, the rocker stop actuator piston may be located on the rocker arm and arranged to work with a damper assembly positioned on a stationary part of the overhead, such as a rocker shaft pedestal. The use of a damper ensures a smooth transition into the LIVC dwell. In an alternative embodiment, the rocker motion stop actuator piston may be located within a stationary housing to contact the valve or cam side of the rocker arm.

[0014] Subsequently, the rocker arm and the corresponding valve closing timing may be controlled based on a separate system. For example, as described above and according to the teachings of the prior art, this may be done using an electronically controlled high-speed solenoid valve. However, according to the present disclosure, a crank-angle-based reset mechanism may provide a predetermined intake valve closing timing by releasing hydraulic fluid from a high-pressure volume that otherwise maintains the actuator piston in a fixed, extended position (thereby maintaining the rocker arm / valve in an open position).

[0015] In various embodiments, the reset is triggered by the relative position of the cam to the rocker arm. As the rocker stop actuator piston keeps the rocker stationary, the cam is still moving away from the rocker when the cam approaches the normal closed position. A reset mechanism between the rocker and the cam (or a push rod connected to the cam) can be used to time the reset of the actuator piston with respect to the crank angle so that the rocker arm and the valve can be fully closed.

[0016] In one embodiment, when the motion-stopped actuator piston is reset, the valve settling speed is controlled by a valve catch (similar in configuration to a damper). The valve catch may be activated only in LIVC mode by selectively switching the oil supply to the valve catch. In this embodiment, the valve catch may be positioned in a fixed part of the engine overhead environment and may be configured to engage with a rocker arm to control shock loads and valve train dynamics. In another embodiment, a closing ramp is provided in the sub-base cam profile, wherein the reset mechanism causes the actuator piston to collapse at a predetermined speed so that the rocker arm follows the sub-base closing ramp.

[0017] According to one aspect of the present disclosure, a valve actuation system for actuating at least one engine valve comprises: a rocker for transmitting motion to at least one valve; a motion source arranged to impart motion to the rocker, the motion source defining a main event peak lift for at least one engine valve; a rocker stop assembly configured to operate in an active mode and an inactive mode, wherein in the active mode the rocker stop assembly maintains the rocker at a position corresponding to a partial valve lift, and in the inactive mode the rocker stop assembly enables the rocker to move to a position corresponding to a fully closed valve position; and a rocker stop reset assembly for resetting the rocker stop assembly to the inactive mode following the main event peak lift to achieve a subsequent valve closing.

[0018] According to a further embodiment of the present disclosure, a rocker stop assembly may be positioned on the rocker or elsewhere in the valve train. The rocker stop assembly may be positioned on the cam side of the rocker. The rocker stop assembly may include a hydraulically actuated piston.

[0019] According to an additional embodiment, the rocker stop reset assembly may be configured to reset the rocker stop assembly to an inactive mode at a predetermined rotational angle of the engine crankshaft or cam. The rocker stop reset assembly may include a plunger configured to extend to occupy the lash between the motion source and the rocker, and further configured to reset the rocker stop assembly to an inactive mode when the plunger extends to a reset position. The rocker stop reset assembly may be configured to maintain the rocker stop assembly in an active mode during a portion of the closed profile of the motion source. According to an additional embodiment, the motion source may be a single cam lobe.

[0020] According to an additional embodiment, the valve actuation system may include a damper assembly arranged to interact with a rocker stop assembly and configured to provide a smooth transition of rocker and valve motion into the later intake valve closing dwell. The damper assembly may be placed in a fixed housing relative to the rocker.

[0021] According to an additional embodiment, the rocker stop assembly and the rocker stop reset assembly may be positioned on the cam side of the rocker. The rocker stop assembly and the rocker stop reset assembly may be connected through at least one hydraulic passage.

[0022] According to an additional embodiment, the motion source may include a sub-base circular cam profile having a closing ramp, wherein the rocker stop reset mechanism is configured to cause the rocker stop assembly to collapse at a predetermined speed so that the rocker arm follows the sub-base circular closing ramp. The rocker stop reset mechanism may be configured to reset the rocker stop assembly to an inactive mode based on the motion source lift and to collapse at a speed independent of the motion source. The rocker stop reset mechanism may include a spring-biased reset piston configured to maintain hydraulic fluid in the rocker stop assembly in an active mode and to vent hydraulic fluid from the rocker stop assembly to the periphery in an inactive mode, and the reset piston is configured to remain open during the collapse of the rocker stop assembly.

[0023] Other aspects and advantages of the present disclosure will become apparent to those skilled in the art from the following detailed description, and such aspects should not be construed as comprehensive or limiting. The foregoing general description and the following detailed description are intended to provide examples of the inventive aspects of the present disclosure and should not be construed as limiting or restricting the scope defined in the appended claims. Brief explanation of the drawing

[0024] The features described in this disclosure are specifically set forth in the appended claims. These features and the accompanying advantages will become apparent by considering the following detailed description taken together with the accompanying drawings. Now, with reference to the following appended drawings in which similar reference numerals denote similar elements, one or more embodiments are described merely as examples. FIG. 1 illustrates a valve operating system of the prior art as described in the aforementioned U.S. Patent Application Publication No. 20030213443; FIG. 2 illustrates a prior art valve operating system such as that described in the aforementioned U.S. Patent No. 7,156,062; FIG. 3 illustrates a prior art valve operating system such as that described in the aforementioned U.S. Patent No. 8,453,613; FIG. 4 is a schematic diagram illustrating exemplary high-level components and sub-components of a valve operating system according to an embodiment of the present disclosure; FIG. 5 is a side perspective view of a valve operating system according to an embodiment of the present disclosure; FIG. 6 is an upper front perspective view of a valve operating system according to an embodiment of the present disclosure; FIG. 7 is a cross-sectional view (in a plane orthogonal to the rocker arm pivot plane) of an exemplary valve actuation system comprising a rocker stop assembly, a rocker stop reset assembly disposed on the motion source side of the rocker arm, and a damper assembly disposed in a fixed housing, all of which conform to aspects of the present disclosure; FIG. 8 is a cross-sectional view (in a plane parallel to the rocker arm pivot plane) of a rocker arm and a rocker stop reset assembly according to an embodiment of the present disclosure; FIG. 9 is a cross-sectional view (in a plane parallel to the rocker arm pivot plane) of a rocker arm, a rocker stop assembly, and a damper assembly disposed in a fixed housing, all according to an embodiment of the present disclosure, wherein the rocker arm is in a valve lift position; FIG. 10 is a cross-sectional view (in a plane parallel to the rocker arm pivot plane) of a rocker stop reset assembly when the rocker arm is in a valve lift position (as shown in FIG. 9), according to an embodiment of the present disclosure; FIG. 11 is a cross-sectional view (in a plane parallel to the rocker arm pivot plane) of a rocker arm, a rocker stop assembly, and a damper assembly disposed in a fixed housing, all according to an embodiment of the present disclosure, wherein the rocker arm is in a damped position and the damper assembly is in a damped transition mode; FIG. 12 is a cross-sectional view (in a plane parallel to the rocker arm pivot plane) of a rocker arm, a rocker stop assembly, and a damper assembly disposed in a fixed housing, all according to an embodiment of the present disclosure, wherein the rocker arm is in a stop position and the damper assembly is in a solid contact dwell position; FIG. 13 is a cross-sectional view of a rocker stop reset assembly in reset mode according to an embodiment of the present disclosure; FIG. 14 is a cross-sectional view of a rocker stop assembly with the actuator piston fully retracted into the actuator bore; FIG. 15 is an exemplary graphic representation of a cam profile as a function of crank angle and normal and LIVC lift profiles achieved using a valve actuation system according to an embodiment of the present disclosure; FIG. 16 is a side perspective view of a second exemplary valve operating system according to an embodiment of the present disclosure; FIG. 17 is an upper front perspective view of the second exemplary valve operating system of FIG. 16; FIG. 18 is a cross-sectional view of a rocker stop reset assembly in reset mode according to an embodiment of the present disclosure; FIG. 19 is a cross-sectional view (in a plane parallel to the rocker arm pivot plane) illustrating an exemplary rocker stop assembly, damper assembly, and valve catch having a rocker arm in a valve lift position according to an embodiment of the present disclosure; FIG. 20 is a cross-sectional view of a rocker arm, a rocker stop assembly, and a damper assembly disposed in a fixed housing, wherein the rocker arm is in a stopped damping position and the damper assembly is in a damping transition mode; FIG. 21 is a cross-sectional view of a rocker arm, a rocker stop assembly, and a damper assembly disposed in a fixed housing, all according to an embodiment of the present disclosure, wherein the rocker arm is in a stop position and the damper assembly is in a solid contact dwell position; FIG. 22 is a cross-sectional view of a rocker stop reset assembly in reset mode according to an embodiment of the present disclosure; FIG. 23 is a cross-sectional view of a rocker arm in valve catch mode according to an embodiment of the present disclosure; FIG. 24 is an exemplary graphic representation of a cam profile as a function of crank angle and normal and LIVC lift profiles achieved using a valve operating system according to an embodiment of the present disclosure. Specific details for implementing the invention

[0025] FIG. 4 is a schematic diagram of the components of a valve operating system according to the present disclosure. Details of specific embodiments of the exemplary system according to this overview of FIG. 4 will become more apparent from the subsequent description with reference to FIG. 5 through 24. The upper-level components and sub-components of the exemplary embodiments according to the present disclosure may include a motion source (or cam) (1), a valve rocker assembly (7), a valve system (13), a controller (14), and a fixed housing (19). An exemplary sub-component of each of these upper-level components is also illustrated, and their functional interactions and / or relationships are also illustrated. For example, the rocker valve assembly (7) may include a motion transmission mechanism or a rocker arm (3), a rocker stop assembly (5) arranged and configured to limit the motion of the rocker arm (3), and a reset mechanism (2) configured to reset the rocker stop assembly (5). For further example, the fixed housing (19) may be a fixed structure (i.e., a rocker shaft pedestal fixed to the rocker arm motion) in an engine overhead environment and may support a hydraulic damper (18) and a valve catch (16) to control the valve settling speed, each of which may interact with the valve rocker assembly (7) to achieve LIVC and other valve motions. Specific embodiments of these upper-level components, subcomponents and their interactions according to the present disclosure will become more apparent from the examples in FIGS. 5 through 24 and the description that follows.

[0026] Referring again to FIG. 4, a motion source (1), which may be a cam or a push tube driven by a cam, is arranged and configured to generate motion to drive a rocker assembly (7). A motion transmission mechanism (3) (e.g., a rocker arm) transmits motion from the cam (1) to the valve (12). In a preferred embodiment, the rocker arm (3) carries a reset mechanism (2) and a motion stop actuator (5) as described below. The entire valve rocker assembly is indicated by reference numeral 7. The cam (1) may be in direct contact with a follower on the valve rocker assembly (7), or may operate in combination with a tappet or a push tube to transmit motion to the rocker assembly (7). The valve rocker assembly (7) may include a reset mechanism (2) configured to maintain the rocker stop in an open state to achieve valve lift dwell and to reset (collapse) the rocker stop at an appropriate crankshaft or cam rotation angle to achieve additional (late) valve closure. In one embodiment, the rocker stop reset mechanism (2) may be positioned on the motion source cam side of the rocker arm (3) and positioned between the motion source (1) and the rocker arm (3). The reset mechanism (2) may have an internal spring arranged to bias the reset mechanism (2) toward the motion source (1). This configuration allows the reset mechanism (2) to pick up any lash generated by the second mode delayed (late) closure (11) (described later).

[0027] A controller (14), such as a programmable engine control module (ECM), can provide control of actuator energy (4) by controlling hydraulic flow and pressure to the rocker stop assembly (5) to create a motion source mismatch (6) that keeps the rocker stop assembly (5) in an extended (expanded) state and thus causes the valve to dwell in a partially lifted state. The rocker stop reset mechanism (2) can operate as a check for the flow of hydraulic fluid from the motion stop actuator (5) when pressurized by a controlled supply of hydraulic oil (4) as the valve (12) opens. The rocker stop reset mechanism (2) can disrupt, reset, or purge the actuator energy (hydraulic fluid) (4) from the rocker stop mechanism (5) to achieve valve closure when triggered in reset mode. The rocker stop reset mechanism (2) can be configured and arranged to be triggered at a specific crank angle on the closed portion of the cam profile. As described in detail below, the rocker stop reset mechanism (2) may include a reset piston or plunger that follows the cam profile. When the reset piston extends more than a certain amount while following the closing portion of the cam profile, one or more reset ports on the reset piston allow the flow of hydraulic fluid from the rocker stop mechanism and will cause the collapse or reset of the rocker stop piston. This consequently allows the rocker to continue the valve closing motion. In an embodiment illustrated in more detail below, the reset mechanism (2) may include a lash adjustment on the cam side.

[0028] The motion stop (5) may be an actuator piston that is slidably positioned in the rocker assembly (7) and is generally biased in the retracted position unless hydraulic energy / pressure (4) extends the actuator piston. The actuator is extended in alignment with the motion source (1) to the extent that the valve (12) opens at peak lift. During operation, oil is checked in the motion stop actuator (5) by the reset mechanism (2) and reacts with the hydraulic damper (18) to keep the motion transmission mechanism, in this case the rocker assembly (7), in a caulked open state until the reset mechanism (2) completely purges the oil in the motion stop actuator (5).

[0029] As is recognized, the operation of the rocker stop mechanism (5), when activated, creates a mismatch (6) between the motion source (1) and the rocker arm (3). That is, when the rocker stop mechanism (5) is activated, the rocker arm does not follow the closing profile of the motion source (1) but rather dwells in a position corresponding to a partial valve lift, thus implementing the desired LIVC operation. When the rocker arm (3) is supported toward the valve (12) to keep the valve (12) open and the cam (1) begins to rotate through its valve closing profile to command the rocker arm (3) and the valve to a closed position, a gap / mismatch (6) begins to form between the cam side of the rocker (3) and the cam (1) (or push tube or other valve train component). As a result of this gap, the reset piston in the reset mechanism (2) may begin to extend to compensate for the gap until it reaches the reset mode, thereby allowing the rocker arm and valve to continue in a fully closed position, thereby achieving LIVC.

[0030] Referring still to FIG. 4, the valve rocker assembly (7) causes the valve system (13) to operate in a first (advance or normal closing) mode (9) or a second (late or delayed closing) mode (11). The normal closing mode (9) is characterized by the valve rocker assembly (7) and rocker arm (3) operating as commanded by the motion source (1) through the cam closing profile, and the rocker stop (5) operating in a non-operational, non-trigger mode (8). On the other hand, the late closing mode (11) is characterized by the valve rocker assembly (7) and rocker arm (3) operating as commanded by the cam (1), except that during the cam closing profile, the rocker stop (5) is activated to cause the valve to dwell in a partially raised state, and then the reset of the reset mechanism (2) resets the rocker stop and achieves a delayed or late valve closing. Reference numeral 10 corresponds to a second mode in which the valve system (13) is commanded by the rotational motion of the cam (1) during valve opening, but the cam (1) dwells in an open state beyond what is actually commanded, thereby opening the gap (6) between the rocker (3) and the cam (1) which is occupied by the reset mechanism (2). Reference numeral 11 indicates a delayed valve closing profile of the second mode (10) corresponding to the same valve opening profile as the first mode (9), but the rocker arm (3) is supported to remain open until released by the reset mechanism (2), resulting in an extended closing profile (or dwell) that causes the valve (12) to close later than usual. Such LIVC dwell may occur at peak cam lift or lower lift, typically at least 3 mm valve lift. As is known in the art, one or more valves (12) may be additionally engaged by a valve bridge, and a set of poppet valves (12) may be biased toward a closed position by a set of valve springs.

[0031] According to a further embodiment of the present disclosure, the controller (14) may optionally activate a self-adjusting valve catch (16) via a solenoid valve and a hydraulic link to minimize the seating speed of the rocker arm during a second mode (10) delayed closing event (11). The valve catch (16) may be activated in both the previously discussed first and second modes (8, 10). The self-adjusting valve catch may be placed in a fixed housing (19) and arranged to work in cooperation with the rocker arm (3).

[0032] According to a further aspect of the present disclosure, the controller (14) may optionally activate a hydraulic damper (18) that provides a smooth transition between the cam-driven closed profile and the LIVC dwell through a control or solenoid valve and a hydraulic link. The hydraulic damper may be placed in a fixed housing (19) and may work in cooperation with the rocker arm stop (5).

[0033] The details and interrelationships of the upper-level components and sub-components described in relation to FIG. 4 will become further apparent from the following description of specific examples and embodiments in FIGs. 5 through 24.

[0034] FIGS. 5 and 6 illustrate a first embodiment of a valve actuation system (100) comprising a rocker shaft pedestal (102) and a rocker arm (104) mounted on the rocker shaft for pivot movement relative to the rocker shaft pedestal (102). For clarity, the rocker shaft is omitted from the example in FIGS. 5 and 6, but as is recognized, the rocker shaft is typically fixed to the rocker shaft pedestal (102) and extends through the journal of the rocker arm (104) to facilitate pivot movement of the rocker arm (104) on the rocker shaft. The rocker arm (104) includes a cam (or motion source) side (106) and a valve side (108). According to an embodiment of the present disclosure, the motion source side (106) of the rocker arm (104) further comprises and accommodates a rocker stop actuator assembly (110) and a rocker stop reset assembly (112), details thereof to be described below. A hydraulic passage (154) of the rocker arm (104) may provide pressurized hydraulic fluid received from a port of the rocker shaft (which in turn receives oil from an upstream pump and oil reservoir as known in the art) to the rocker stop reset assembly (112). An additional passage (130) of the rocker arm (104) may provide a hydraulic link between the rocker stop reset assembly and the rocker stop actuator assembly (110). The rocker stop actuator assembly (110) functions to selectively restrict or stop the pivot movement of the rocker arm (104) when operated hydraulically or mechanically (i.e., restricting movement in the clockwise direction as shown in FIG. 5). Thus, the rocker stop actuator assembly (110) functions to prevent the valve side (108) of the rocker arm (104) from reaching a position corresponding to full valve closure (i.e., thus maintaining the valve in a non-closed or partially raised position for a predetermined time after peak lift to facilitate LIVC).

[0035] Additionally, with further reference to FIG. 7, as illustrated in FIG. 5 and FIG. 6, according to an embodiment of the present disclosure, the rocker stop reset assembly (112) may include a reset plunger (114), which may be biased toward a non-reset position (i.e., maximum downward displacement relative to the upper reset body (140)) by a reset plunger spring (116). The reset plunger (114) extends toward a valve motion source (not shown). The reset plunger (114) may be operably connected to a push tube, which consequently is operably associated with a cam and activated by the cam. The rocker stop reset assembly (112) is configured and arranged to provide a reset of the rocker stop actuator assembly (110) by venting hydraulic fluid from the rocker stop actuator assembly (110) at an appropriate crank or cam rotation angle, for example, thereby allowing a reset (retraction) into the bore (132) of the rocker stop assembly piston (120) through the resulting continuous closing motion of the rocker arm and the resulting closing of the valve in the LIVC operation.

[0036] According to a further embodiment of the present disclosure, a damper assembly (118) may be housed within or extend from a rocker shaft pedestal and may occasionally function to control the movement of a rocker stop actuator assembly (110), a rocker arm (104), and the motion of the valve end (108) and the valve accordingly. As described in more detail below, the damper assembly (118) is configured and arranged to interact with the rocker stop actuator assembly (110) to provide a smooth transition of valve motion, such as the transition between normal (i.e., main event) valve operation motion and a LIVC event. An additional passage (133) may supply hydraulic fluid from the rocker shaft to the damper assembly (118).

[0037] Now, referring to FIG. 7, additional details of the rocker stop actuator assembly (110), rocker stop reset assembly (112), and damper assembly (118) are illustrated in a cross-section taken through the motion source end (106) (Fig. 5) of the rocker arm (104). In particular, the rocker stop actuator assembly (110) may include an actuator piston (120) slidably disposed in an actuator bore (132) formed on the motion source side (106) of the rocker arm (104). As is known in the art, a lash adjustment screw (122) and a lash adjustment nut (124) are provided to allow lash adjustment of the actuator piston (120). An actuator spring retainer (126) may be slidably positioned on a lash screw (122), and an actuator spring (128) is positioned between the shoulder on the lash screw (122) and the actuator spring retainer (126), so that any hydraulic operation of the actuator piston (120) (i.e., appropriate hydraulic pressure in the bore (132)) is absent, and the actuator piston (120) is biased to retract into the actuator bore (132).

[0038] The operation of the rocker stop actuator assembly (110) can be controlled via a hydraulic actuation circuit or link comprising various passages within the components of the valve train, as described in detail below. The hydraulic actuation circuit may include a first hydraulic passage (130) that is hydraulically in communication with the actuator bore (132). Although not shown in FIG. 7, the first hydraulic passage (130) is fluidly in communication with a second hydraulic passage (158) (Fig. 8) by an additional passage within the rocker arm (i.e., a fly-cut area connecting passage (158) to the passage (130)) that may allow for the supply of hydraulic fluid to the first hydraulic passage (130) and the actuator bore (132) selectively (e.g., under the control of a solenoid valve) to actuate the rocker stop assembly. As is recognized, these additional passages can provide fluid communication from passage (158) to passage (130) and to actuator bore (132) regardless of the state of the rocker stop reset assembly (reset mode or non-reset mode).

[0039] The rocker stop reset assembly (112) comprises an upper reset body (140) and a separate lower reset body (144), both of which can be fastened to the rocker arm (104) by a screw fitting, and both have an internal bore that guides and allows the sliding movement of the reset plunger (114). The upper reset body (140) may include a lash adjustment screw (and a corresponding lash adjustment nut (142)) that facilitates lash adjustment of the reset plunger (114). The lower reset body (144) is fixedly attached (e.g., screwed) to the rocker arm (104) so ​​that the reset plunger (114) extends from the lower reset body (144) toward a valve operating motion source (e.g., a push tube and a cam (not shown)) (i.e., downward in FIG. 7). A reset plunger spring (116) is positioned between the respective shoulders formed in the lower reset body (144) and formed in the lower portion of the reset plunger (114) so ​​that the reset plunger (114) is contact-biased with the motion source (i.e., downward-biased in FIG. 7). The upward movement of the reset plunger (114) (i.e., into the longitudinal channel formed in the upper reset body (140)) is restricted when solid contact occurs between the lower reset body shoulder (150) and the reset plunger shoulder (152). As illustrated, the reset plunger (114) further includes a venting passage (146) formed inside the reset plunger and configured to provide fluid communication with the surrounding atmosphere and an oil return path (i.e., into the overhead environment through a suitable passage to the oil pan and through which drip / flow) in the engine overhead environment. As further described in detail in relation to FIG. 8, the reset port (148) is formed in the reset plunger (114) and is provided as a radial opening (i.e., a radial extension port) that is fluidly in communication with the venting passage (146).

[0040] FIG. 8 illustrates additional details in cross-section of the rocker stop reset assembly (112) and the rocker arm (104). As illustrated, the rocker arm (104) includes a fourth hydraulic passage (154) configured to receive hydraulic fluid optionally applied from the rocker arm shaft (not shown) using known techniques. The check valve assembly (156) provides unidirectional fluid communication using the fourth hydraulic passage (154) and the second hydraulic passage (158). A spill port (160) formed in the upper reset body (140) provides optional (i.e., depending on the position of the lower reset body (144)) hydraulic communication with the volume established by the actuator bore (132), the first hydraulic passage (130), and the second hydraulic passage (158).

[0041] As described in more detail below, in the extended mode of the rocker arm stop assembly (110), the reset plunger (114) may be in the lower position shown in FIG. 7 relative to the upper reset body (140), and the outer diameter of the reset plunger (114) may seal the second hydraulic passage (158), thereby sealing the volume established by the actuator bore (132), the first hydraulic passage (130), and the second hydraulic passage (158). During such operation, pressurized hydraulic fluid from the fourth hydraulic passage (154) enters the actuator bore (132) and overcomes the bias applied by the actuator piston spring (128) to cause the actuator piston (120) to extend from the actuator bore (132).

[0042] According to an embodiment of the present disclosure, the rocker stop reset assembly (140) facilitates the reset mode of the rocker arm stop assembly (110), and as the reset plunger (114) translates (i.e., downward in FIG. 7) within the upper reset housing (140) (due to the application of a valve operating motion to the upper reset housing), the reset port (148) formed in the reset plunger (114) will be periodically aligned with the spill port (160). During such operation, the hydraulic fluid trapped within the actuator bore (132) is allowed to escape through the flow path established by the first hydraulic passage (130), the second hydraulic passage (158), the spill port (160), the reset port (148), and the venting passage (146), thereby allowing the actuator piston (120) to retract once again into the actuator bore (132).

[0043] The damper assembly (118) includes a damper piston (134) and a base (136). A third hydraulic passage (133) is provided to the rocker shaft pedestal (102), and the rocker shaft pedestal supplies hydraulic fluid through an opening (135) of the base (136) and into the space between the base (136) and the damper piston (134). As additionally illustrated, the damper piston (134) also includes a protrusion (137), which can align with and seal the opening (135) when the protrusion (137) contacts the base (136). The supply of pressurized hydraulic fluid to the damper assembly (118) may be continuous or selectively switched via a suitable control device (e.g., a solenoid). When hydraulic fluid is present in the space between the damper piston (134) and the base (136), the downward pressure applied to the damper piston (134) by the actuator piston (120) will cause the hydraulic fluid to flow back into the third hydraulic passage (133) through the opening (135). The continuous downward translational movement of the damper piston (134) and the protrusion (137) will gradually reduce the flow area between the protrusion and the opening (135), thereby gradually slowing down the flow of the hydraulic fluid and, consequently, slowing down the translational speed of the damper piston (134) until the protrusion (137) comes into contact with the base (136), thereby stopping any further translational movement of the damper piston (134).

[0044] FIG. 15 illustrates an intake cam profile (170) suitable for use with the embodiments illustrated in FIGS. 5 through 14. In particular, the cam profile (170) illustrates a main intake event (172) that facilitates positive power generation in the fueled cylinder of an internal combustion engine, as is known in the art. The cam profile (170) further includes a so-called sub-base circular feature comprising a second closing ramp (174) used during the LIVC operation of the valve actuation system (100) of FIGS. 5 through 8. During the normal main event (172) operation, hydraulic fluid is not supplied to the actuator bore (132), thereby preventing the extension of the actuator piston (120). Consequently, the actuator piston (120) will not engage with the damper piston (134) so ​​that the rocker arm can be closed in a normal manner, i.e., according to the first closing ramp (176) without LIVC operation. However, during the LIVC operation, hydraulic fluid is supplied to (and captured within) the actuator bore (132), and accordingly, the actuator piston (120) will be maintained in its extended position, thereby maintaining the engine valve in the open position (180) to provide the desired LIVC operation. The interaction between the actuator piston (120) and the damper piston (134) (Fig. 7) provides a smooth transition (178) between the main event lift (172) and the LIVC dwell (180). As described in more detail below, the subsequent operation of the rocker stop reset assembly (112) will cause the actuator piston (120) to collapse, providing a closing event (182) commanded by the second closing ramp (174).

[0045] In particular, additional operations of the embodiments illustrated in FIGS. 5 through 8 during LIVC operation are further illustrated with reference to FIGS. 9 through 15. FIG. 9 illustrates the state of the actuator piston (120) and damper piston (134) during the opening ramp of the main event (172) and prior to the LIVC transition (178) (as illustrated in FIG. 15). During this time, the main event lift (172) will provide sufficient space between the actuator piston (120) and the damper piston (134), thereby filling the actuator bore (132) with hydraulic fluid, and thereby causing the actuator piston (120) to extend to its maximum position (in this example, as indicated by the solid contact between the actuator piston spring retainer (126) and the shoulder (162) formed on the lash screw (122).

[0046] As further illustrated in FIG. 9, simultaneously with the extension of the actuator piston (120), hydraulic fluid supplied to the damper assembly (118) through the third hydraulic passage (133) and, for example, under the control of the control valve and / or porting on the rocker shaft will flow through the opening (135) to fill the space between the base (136) and the damper piston (134), thereby causing the damper piston (134) to extend out of its bore, that is, generally toward the rocker arm (104) and the actuator piston (120) (i.e., upward in FIG. 9). As further illustrated in FIG. 9, in addition to the opening (135), a checked passage (164) may be provided to the base (136) so that the fluid can fill the space between the base (136) and the damper piston (134) more quickly during valve opening.

[0047] FIG. 10 illustrates the operation of the reset assembly and plunger (114) during the same period illustrated in FIG. 9, that is, during valve opening and prior to LIVC transition (178). During this time, the valve lift provided by the main event (172) will overcome any bias applied by the reset plunger spring (116), thereby causing the reset plunger (114) to translate upward to solid contact between the respective shoulders (150, 152) of the lower reset body (144) and the reset plunger (114), as illustrated. In particular, this upward translation of the reset plunger (114) will cause the reset port (148) to move past the spill port (160), which will instead be sealed by the outer diameter of the reset plunger (114), as illustrated. As a result, the hydraulic fluid in the actuator bore (132) is prevented from venting, and instead the actuator piston (120) is maintained in its extended position.

[0048] Now, referring to FIG. 11, the state of the actuator piston (120) and damper piston (134) at that time when the fully extended actuator piston (120) and damper piston (134) come into contact with each other during the closing ramp of the main event (172) is illustrated. Referring to the example illustrated in FIG. 15, this occurs at approximately 6 mm intake valve lift (assuming zero valve lash) or a crank angle of approximately 520 degrees. Also, in this example, the stroke length of the damper piston (134) (i.e., the distance between the damper piston (134) and the base (136) when the damper piston (134) is fully extended) is assumed to be 2 mm.

[0049] As the hydraulic damper piston (134) is pressed downward by the fully extended actuator piston (120), hydraulic fluid is forced through the opening (135) within the hydraulic damper base (136). The curtain flow area between the lower protrusion (137) of the hydraulic piston and the opening (135) is gradually reduced as the damper piston (134) moves downward, thereby throttling the flow of hydraulic fluid back into the third hydraulic passage (133) and providing a smooth transition (178) to the LIVC "back porch" dwell (180) (Fig. 15). Consequently, the dwell (180) is provided when the damper piston (134) establishes solid contact with the base (136), thereby causing the fully extended actuator piston (120) to keep the rocker arm (and consequently the intake valve(s)) in an open position. FIG. 12 illustrates such a LIVC back porch lift condition or dwell (180), where the damper piston (134) is at the bottom of the base (136), while the actuator piston (120) is maintained in a fully extended position. As illustrated in the example of FIG. 15, the dwell (180) is maintained with an intake valve lift of approximately 3.5 mm for a crank angle of about 60 to 70 degrees.

[0050] During the transition period (178) and LIVC dwell (180), a mismatch or gap (184) (or 1284 in FIG. 24) occurs between the lift maintained at the intake valve(s) and the cam profile (170). As illustrated in FIG. 13, this causes the reset plunger (114) to follow the cam profile (170) (Fig. 15) under a bias applied by the reset plunger spring (116), thereby causing it to translate downward within the longitudinal channel formed in the upper reset body (140). This is illustrated in FIG. 13 by the gap created between the lower reset body (144) and the reset plunger (114). This process of the reset piston (114) following the cam profile (170) while the rocker arm (104) and intake valve(s) are maintained in the LIVC dwell (180) continues until the reset port (148) begins to align with the spill port (160). As shown in FIG. 13, as soon as a slight overlap is provided between the reset port (148) and the spill port (160), the pressurized fluid trapped in the actuator bore (132) (as well as the first hydraulic passage (130) and the second hydraulic passage (158)) can be vented to the atmosphere through the flow paths provided by the outflow port (160), the reset port (148), and the venting passage (146). Consequently, this allows the actuator piston (120) to retract back into the actuator bore (132) at a predetermined speed indicated by the velocity of the fluid venting through the spill port (160), reset port (148), and venting passage (146). As the actuator piston (120) retracts, the rocker arm (104) rotates toward the cam, while the reset plunger (114) simultaneously follows the cam profile (170). In this case, the reset piston (114) will be "dithered" so that the reset port (148) and spill port (160) are maintained in this slightly overlapping position while the rocker arm (104) continues to rotate toward valve closure.In this way, the valve lift closing event (182) is effectively commanded by the closing ramp (174) of the cam profile (170). As illustrated in FIG. 14, this process of gradual valve closing continues until the actuator piston (120) is fully retracted into the actuator bore (132).

[0051] FIGS. 16 and 17 illustrate a second embodiment of the valve actuation system (1200). Similar reference numerals shown in FIGS. 5, 6, 16, and 17 refer to structures that are structured and operated in substantially the same manner. Thus, the rocker stop actuator assembly (1110) and the damper assembly (1118) may be substantially similar to the rocker stop actuator assembly (1110, 1118) in the first embodiment. In contrast, as described below, the reset assembly (1212) may be structured and may operate somewhat differently compared to the first embodiment illustrated in FIGS. 5 and 6. Additionally, a self-adjusting valve catch (SAVC) (1300) is provided in the second embodiment illustrated in FIGS. 16 and 17. The SAVC assembly (1300) may be substantially similar in configuration and operation to the self-regulating valve catch disclosed in U.S. Patent No. 8,079,338, the entire disclosure and teaching of which is included by reference.

[0052] FIG. 18 illustrates additional details in cross-section of the reset assembly (1212) and rocker arm (1104) according to the second embodiment. Once again, the rocker arm (1104) includes a fourth hydraulic passage (1154), a check valve assembly (1156), and a second hydraulic passage (1158), while the rocker stop reset assembly (1112) assembly again includes an upper reset body (1140) and a lower reset body (1144). However, in this embodiment, the reset plunger (1214) extends only through a longitudinal channel formed in the lower reset body (1144), and the reset plug (1241) is provided with a reset port (1248) formed therein. In this case, the reset plug (1241) is fixedly maintained within a longitudinal channel formed in the upper reset body (1140) so that the reset port (1248) is continuously aligned with the spill port (1160) formed in the upper reset body (1140). The reset plug (1241) further includes a central passage (1242) that is in fluid communication with the reset port (1248).

[0053] A reset piston (1245) is slidably positioned in a longitudinal channel formed in the upper reset body (1140). As illustrated, the reset piston (1245) has a central upper surface (1247) that aligns with the central passage (1242) of the reset plug (1241). The reset piston (1245) further includes one or more channels (1249) that extend from the periphery of the central upper surface (1247) and provide fluid communication with the internal region of the reset piston (1245). The reset piston (1245) is biased to contact the reset plug (1241) by a reset piston spring (1251) positioned between the reset piston (1245) and the reset plunger (1214). As illustrated, the internal region of the reset piston (1245) consequently fluidly communicates with the venting passage (1246) formed in the reset plunger (1214). Under the premise that the biasing force applied by the reset piston spring (1251) is greater than any counteracting hydraulic force applied to the reset piston (1245) through the center passage (1242), the reset piston (1245) will be kept in contact with the reset plug (1241), thereby preventing any fluid flow through the center opening (1242), channel (1249), and venting passage (1246).

[0054] FIG. 24 illustrates an intake cam profile (1270) suitable for use with the second embodiment illustrated in FIG. 16 through 23. In particular, the cam profile (1170) illustrates the main intake event (1172) as described above. The cam profile (1270) further includes a closing ramp (1176). Once again, during the normal main event (1172) operation, hydraulic fluid is not supplied to the actuator bore (1132) (Fig. 19), thereby preventing the extension of the actuator piston (1120). Consequently, the actuator piston (1120) will not engage with the damper piston (134), allowing the rocker arm to close (1176) in a normal manner, i.e., without LIVC operation. However, during the LIVC operation, hydraulic fluid is once again supplied to (and captured within) the actuator bore (1132), and accordingly, the actuator piston (1120) will be maintained in its extended position, thereby maintaining the engine valve in the open position (1280) to provide the desired LIVC operation. The interaction between the actuator piston (1120) and the damper piston (1134) again provides a smooth transition (1278) between the main event lift (1172) and the LIBC dwell (1280). As described further in detail below, the subsequent operation of the reset assembly (1212) causes the actuator piston (1120) to collapse, thereby providing a valve seating profile (1283) controlled by the closing event (1282) and SAVC (1300), as described further in detail below.

[0055] Referring again to FIG. 18, the state of the reset plunger (1214) and the reset piston (1245) is shown during the opening ramp of the main event (1172) and before the LIVC transition (1278) (as shown in FIG. 24). That is, despite the presence of fluid in the second hydraulic passage (1158) and the reset port (1248), the bias of the reset piston spring (1251) is sufficient to keep the reset piston (245) in a sealing engagement with the center passage (1242), which consequently allows the actuator piston (1120) to extend out of the actuator bore (1132) as previously described.

[0056] As further illustrated in FIG. 19, simultaneously with the extension of the actuator piston (1120), the hydraulic fluid supplied to the damper assembly (1118) through the third hydraulic passage (1133) will flow through the opening (1135) and past the protrusion (1137) to fill the space between the base (1136) and the damper piston (1134), thereby extending the damper piston (1134) as described above. As further illustrated, in this embodiment, the third hydraulic passage (1133) is further extended to a SAVC assembly (1300) which operates essentially identically to the damper assembly (1118), although in this embodiment. That is, as illustrated, the SAVC assembly (1300) includes a slidable SAVC base (1302) disposed in a SAVC bore (304) that is in fluid communication with the third hydraulic passage (133). An inner chamber (1307) is formed in the SAVC base (1302), and an opening (1306) (with an optional checked passage as illustrated) provides fluid communication between the third hydraulic passage (1133) and the inner chamber (1307). A SAVC plunger (1308) is positioned in the inner chamber and is biased upward toward the opening (1306) by a SAVC plunger spring (1310). The SAVC plunger (1308) further includes a protrusion (1309) aligned with the opening (1306). As described, the hydraulic pressure provided by the third hydraulic passage (1133) causes fluid to enter the inner chamber (1307), and this fluid is pressurized sufficiently to overcome any biasing force applied by the SAVC plunger spring (1310), causing the protrusion (1309) to be disengaged from the opening (1306). Additionally, as described in U.S. Patent No. 8,079,338, the leakage of pressurized hydraulic fluid passing through the SAVC plunger (1308) results in a substantially constant volume of fluid filling the space formed by the inner region of the SAVC plunger (1308) and the wall of the SAVC bore (1304).

[0057] Now, referring to FIG. 20, the state of the actuator piston (1120) and damper piston (1134) at that time when the fully extended actuator piston (1120) and damper piston (1134) come into contact with each other during the closing ramp of the main event (1172) is illustrated. Referring to the example illustrated in FIG. 24, this occurs once again at an intake valve lift of approximately 6 mm (assuming zero valve lash) or a crank angle of approximately 1520 degrees. Additionally, in this example, the stroke length of the damper piston (1134) is again assumed to be 2 mm.

[0058] As described above, continuous interaction between the fully extended actuator piston (1120) and the damper piston (1134) provides a smooth transition (1278) to the LIBC "back porch" dwell (1280). Once again, the dwell (1280) is provided when the damper piston (1134) is in the bottom position with the base (1136), thereby causing the fully extended actuator piston (1120) to maintain the rocker arm (and consequently the intake valve(s)) in the open position. FIG. 21 illustrates this LIVC back porch lift condition or dwell (1280), where the damper piston (1134) is in the bottom position on the base (1136), while the actuator piston (1120) is maintained in the fully extended position. As illustrated in the example of FIG. 24, the dwell (1180) is maintained with an intake valve lift of approximately 3.5 mm for a crank angle of about 20 to 30 degrees.

[0059] Once again, during the transition period (1278) and LIVC dwell (1280), a mismatch or gap (1276) occurs between the lift maintained at the intake valve(s) and the cam profile (270). As illustrated in FIG. 22, this causes the reset plunger (1214), under a bias applied by the reset plunger spring (1116), to follow the cam profile (1170), particularly the closing ramp (1176), thereby allowing it to translate downward within the longitudinal channel formed in the lower reset body (1144). This is illustrated in FIG. 22 by the gap created between the lower reset body (1144) and the reset plunger (1214). This process of the reset piston (1214) following the cam profile (1270) while the rocker arm (1104) and intake valve(s) are maintained in the LIVC dwell (1280) continues until the spring force applied by the reset piston spring (1251) drops below the hydraulic force applied to the reset piston (1245), causing the reset piston (1245) to translate downward. This consequently opens a fluid path into the venting passage (1246) through the spill port (1160), reset port (1248), and channel (1249). In this case, unlike the aforementioned "dithering" embodiment, the spill port (1160) remains substantially open, because the hydraulic force on the reset piston (1245) increases significantly due to the large increase in pressure area and the fact that most of the pressure drop occurs across the channel (1249) formed in the reset piston (1245). As a result, the actuator piston (1120) will instead retract quickly into the actuator bore (1132), which also causes the rocker arm (1104) and intake valve(s) to close equally quickly, which may result in undesirable shock during valve seating.

[0060] To this end, the SAVC assembly (1300) engages with the rocker arm (1104) and operates to provide a gradual valve settling event (1283). In particular, as the rocker arm (1104) rotates toward the motion source, the extension (1340) of the rocker arm engages with the SAVC base (1302), thereby forcing it into the SAVC bore (1304) and compressing the hydraulic fluid in the inner chamber (1307). However, at the same time, the volume of fluid trapped behind the SAVC plunger (308) prevents the SAVC plunger (1308) from retracting further into the SAVC bore (1304). Consequently, as the SAVC base (1302) is displaced downward, the relative lack of movement of the SAVC plunger (1308) causes the hydraulic fluid to be discharged back into the third hydraulic passage (1133) through the opening (1306) from the reduced volume of the inner chamber (1307). As the SAVC base (1302) approaches the SAVC plunger (1308), the continuously reduced flow area between the protrusion (1309) and the opening (1306) increases resistance to the escaping hydraulic fluid, thereby smoothly slowing down further descent of the SAVC base (1302). This process continues until, as illustrated in FIG. 23, the protrusion (1309) fully engages with and seals the opening (1306), thereby preventing further escape of the hydraulic fluid and further descent of the SAVC base (1302). As additionally illustrated in FIG. 23, the gradual valve closing process also continues until the actuator piston (1120) is fully retracted into the actuator bore (1132).

[0061] Although preferred embodiments have been illustrated and described, those skilled in the art will understand that changes and modifications may be made without departing from the teachings of the invention. Accordingly, any and all modifications, variations, or equivalents of the teachings described above will be considered to be within the scope of the basic fundamental principles disclosed above.

[0062] For example, while the rocker motion stop actuator piston is positioned on the rocker arm in the described embodiment, other arrangements will be recognized as being within the scope of the present disclosure. For example, the rocker motion stop actuator piston may be positioned in a fixed housing (rocker shaft pedestal) and arranged to contact the cam side of the rocker arm. Alternatively, the rocker motion stop may be positioned on the valve side of the rocker arm and arranged and configured to be positioned inside it or in the fixed housing.

Claims

Claim 1 A valve actuation system for actuating at least one engine valve of an internal combustion engine, comprising: a rocker for transmitting motion to said at least one engine valve; a motion source arranged to impart motion to the motion source side of said rocker so that said rocker moves relative to the cylinder head of said internal combustion engine, said motion source defining a main event peak lift for said at least one engine valve; and a rocker stop assembly at least partially coupled to said cylinder head and configured to operate in an active mode and an inactive mode, said rocker stop assembly, said rocker stop assembly, in the active mode, initially allows said motion source side of said rocker to move as commanded by said motion source, and after said main event peak lift, maintains said motion source side of said rocker in a position corresponding to the valve lift so that said motion source side of said rocker is not commanded by the closing profile of said motion source, said rocker stop assembly A valve operating system comprising a rocker stop reset assembly configured to achieve a subsequent valve closure by resetting the rocker stop assembly to the deactivation mode based on the position of the rocker on the motion source side relative to the motion source following the main event peak lift, wherein the rocker stop reset assembly is a plunger configured to extend to occupy the lash between the motion source and the rocker, and further configured to reset the rocker stop assembly to the deactivation mode when the plunger extends to the reset position. Claim 2 In claim 1, the rocker stop assembly is a valve operating system disposed in the rocker. Claim 3 In claim 1, the rocker stop assembly is a valve operating system disposed on the cam side of the rocker. Claim 4 In paragraph 1, the rocker stop assembly is a valve operating system comprising a hydraulically actuated piston. Claim 5 A valve operating system according to claim 1, wherein the rocker stop reset assembly is configured to reset the rocker stop assembly to the deactivation mode at a predetermined rotational angle of the engine crankshaft or cam. Claim 6 delete Claim 7 A valve operating system according to claim 1, wherein the rocker stop reset assembly is configured to maintain the rocker stop assembly in the activation mode during part of the closed profile of the motion source. Claim 8 In claim 1, the motion source is a single cam lobe, a valve actuation system. Claim 9 A valve actuation system according to claim 1, further comprising a damper assembly arranged to interact with the rocker stop assembly and configured to provide a smooth transition of the rocker and valve motion to a later intake valve closing dwell. Claim 10 In claim 9, the valve operating system, wherein the damper assembly is disposed in a fixed housing relative to the rocker. Claim 11 A valve operating system according to claim 1, further comprising a valve catch assembly arranged to interact with the rocker and configured to control the seating speed of the at least one valve. Claim 12 In claim 11, the valve catch assembly is disposed in a fixed housing relative to the rocker, in a valve operating system. Claim 13 A valve operating system according to claim 11, wherein the valve catch assembly is arranged to interact with a projection on the cam side of the rocker. Claim 14 A valve operating system according to claim 1, wherein the rocker stop assembly and the rocker stop reset assembly are disposed on the cam side of the rocker. Claim 15 A valve operating system according to claim 1, wherein the rocker stop assembly and the rocker stop reset assembly are connected through at least one hydraulic passage. Claim 16 A valve operating system according to claim 1, wherein the motion source comprises a sub-base circular cam profile having a closing ramp, and the rocker stop reset assembly is configured to cause the rocker stop assembly to collapse at a predetermined speed so that the rocker arm follows the sub-base circular cam profile closing ramp. Claim 17 A valve operating system according to claim 1, wherein the rocker stop reset assembly is configured to reset the rocker stop assembly to the deactivation mode based on the motion source lift and collapse at a speed independent of the motion source. Claim 18 A valve actuation system according to claim 17, wherein the rocker stop reset assembly comprises a spring-biased reset piston configured to maintain hydraulic fluid in the rocker stop assembly in the activated mode and vent hydraulic fluid from the rocker stop assembly to the periphery in the deactivated mode, and the reset piston is configured to remain open during the collapse of the rocker stop assembly.

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