Rocker Arm Assemblies for Engine Braking

This application claims the benefit under 35 U.S.C. § 365(c) of International Patent Application No. PCT/EP2024/025070, filed 9 Feb. 2024, which claims the benefit under 35U.S.C. § 119(e) of U.S. Provisional Patent Application No. 63/493,680 filed 31 Mar. 2023, and U.S. Provisional Patent Application No. 63/501,331 filed 10 May 2023, which are incorporated herein by reference in their entirety.

This application relates to engine valvetrains, and more particularly to rocker arm assemblies for use in engine valvetrain assemblies to facilitate engine braking functions.

Internal combustion engines may include valvetrains, wherein, in particular configurations, engine valvetrains may include rocker arms for controlling the opening and closing of intake and/or exhaust valves.

Particular embodiments of engines may include an engine braking system that, when activated, can provide early and/or additional opening of an exhaust valve. For example, an exhaust valve may be additionally opened early when the piston in that cylinder may be near a top dead center (TDC) position of its compression stroke. By such opening of an exhaust valve by the engine braking system, compression gases may be released by compression release through the exhaust valve. This may cause an engine to function as a power consuming device, which may assist in slowing the vehicle.

In particular embodiments, a rocker arm assembly is disclosed, the rocker arm assembly rotatable about a rocker shaft and including: a first portion configured to receive a valve lift profile; and a second portion configured to operatively engage with one or more valves based on the valve lift profile, the second portion including: an actuator assembly switchable between a first state and a second state, the actuator assembly including a valve mechanism actuated by a control member; and a plunger assembly having a plunger axis angled to a longitudinal axis of the actuator assembly, the plunger assembly including: an elongated member having a first end and a second end opposite the first end; a plunger pad slidably disposed at the first end of the elongated member; and a lash adjustment mechanism associated with the second end of the elongated member, wherein the control member of the actuator assembly is hydraulically actuated to act on the valve mechanism, and wherein, based on an actuation of the actuator assembly, the plunger pad is selectively extendable relative to the elongated member along the plunger axis between a retracted position and an extended position.

In particular embodiments, which may combine the features of some or all of the above embodiments, the plunger assembly further includes: a collar secured to the plunger pad; and a plunger biasing member disposed between the first end of the elongated member and the collar, wherein the plunger biasing member is configured to bias the plunger pad toward the retracted position.

In particular embodiments, which may combine the features of some or all of the above embodiments, corresponding to the second state of the actuator assembly, an extending force based on hydraulic pressure acts to overcome a force associated with the plunger biasing member such that the plunger pad extends to the extended position. In particular embodiments, which may combine the features of some or all of the above embodiments, the plunger biasing member includes a spring.

In particular embodiments, which may combine the features of some or all of the above embodiments, an inner surface of the plunger pad includes a detent, and the elongated member of the plunger assembly further includes a locking assembly provided proximal to the first end and configured to engage with the detent.

In particular embodiments, which may combine the features of some or all of the above embodiments, corresponding to the second state of the actuator assembly, an extending force based on hydraulic pressure acts to overcome a detent force associated with the locking assembly engaging with the detent such that the plunger pad extends to the extended position.

In particular embodiments, which may combine the features of some or all of the above embodiments, the detent includes a groove, and wherein the locking assembly includes a protruding feature and a lock biasing member, the lock biasing member configured to bias the protruding feature toward the groove. In particular embodiments, which may combine the features of some or all of the above embodiments, the lock biasing member is disposed along a lock axis angled to the plunger axis. In particular embodiments, which may combine the features of some or all of the above embodiments, the lash adjustment mechanism is accessible via an upper surface of the rocker arm assembly to facilitate lash adjustment of the plunger assembly.

In particular embodiments, which may combine the features of some or all of the above embodiments, the lash adjustment mechanism extends above the upper surface of the rocker arm assembly. In particular embodiments, which may combine the features of some or all of the above embodiments, the longitudinal axis of the actuator assembly is oriented perpendicular to the plunger axis.

In particular embodiments, which may combine the features of some or all of the above embodiments, the second portion further includes a lost motion assembly configured to absorb at least a portion of the valve lift profile. In particular embodiments, which may combine the features of some or all of the above embodiments, the lost motion assembly includes: a lost motion shaft movable within a bore provided along a longitudinal axis of the lost motion assembly; and a lost motion biasing member configured to bias the lost motion shaft toward the one or more valves.

In particular embodiments, which may combine the features of some or all of the above embodiments, the longitudinal axis of the lost motion assembly is disposed parallel to the plunger axis of the plunger assembly. In particular embodiments, which may combine the features of some or all of the above embodiments, the first portion of the rocker arm assembly includes a roller configured to engage with a cam to receive at least a portion of the valve lift profile.

In particular embodiments, which may combine the features of some or all of the above embodiments, corresponding to the first state of the actuator assembly, the valve mechanism is held open by the control member so that the plunger pad retracts to the retracted position. In particular embodiments, which may combine the features of some or all of the above embodiments, a rocker arm assembly, the valve mechanism includes a check valve biased against a hydraulic channel opening by a check valve biasing member.

In particular embodiments, which may combine the features of some or all of the above embodiments, the control member includes a control pin biased against the check valve by a control biasing member, the control member movable along the longitudinal axis of the actuator assembly.

In particular embodiments, which may combine the features of some or all of the above embodiments, a method of assembling a rocker arm assembly is disclosed, including: providing a plunger assembly proximal to a valve-engaging portion of the rocker arm assembly, the plunger assembly including an elongated member, a plunger pad slidably disposed at a first end of the elongated member, and a lash adjustment mechanism associated with a second end of the elongated member disposed opposite the first end; providing a hydraulic actuator assembly connected in fluid communication with the plunger assembly such that a longitudinal axis of the hydraulic actuator assembly is angled to a plunger axis of the plunger assembly; and configuring the second end of the elongated member to be accessible via an upper surface of the rocker arm assembly to facilitate lash adjustment of the plunger assembly.

In particular embodiments, which may combine the features of some or all of the above embodiments, a valvetrain system is disclosed, including: a cam provided with a valve lift profile; one or more valves; a rocker shaft; and a rocker arm assembly rotatable about the rocker shaft, the rocker arm assembly including: a first portion configured to receive the valve lift profile; and a second portion configured to operatively engage with one or more of the valves based on the valve lift profile, the second portion including: an actuator assembly switchable between a first state and a second state, the actuator assembly including a valve mechanism actuated by a control member; and a plunger assembly having a plunger axis angled to a longitudinal axis of the actuator assembly, the plunger assembly including: an elongated member having a first end and a second end opposite the first end; a plunger pad slidably disposed at the first end of the elongated member; and a lash adjustment mechanism associated with the second end of the elongated member, wherein the control member of the actuator assembly is hydraulically actuated to act on the valve mechanism, and wherein, based on an actuation of the actuator assembly, the plunger pad is selectively extendable relative to the elongated member along the plunger axis between a retracted position and an extended position.

It should be noted that figures provided may be illustrated schematically rather than literally or precisely; components and aspects of the figures may also not necessarily be to scale. Moreover, while like reference numerals may designate corresponding parts throughout the different views in many cases, like parts may not always be provided with like reference numerals in each view.

In accordance with various embodiments of the present disclosure, rocker arm assemblies and related mechanisms, devices, and methodologies are provided herein. While this disclosure may include particular embodiments having specific features and combinations of features as well as particular use cases to provide a better understanding, it will be appreciated that this disclosure is not limited to these particular exemplary embodiments or use cases.

In particular embodiments, engine valvetrains may include rocker arms for controlling the opening and closing of intake and/or exhaust valves of an engine. In particular embodiments, a rocker arm may comprise a reciprocating body that may translate rotational motion, such as from a cam lobe of a rotating camshaft lobe, into motion that can control the opening and closing of a valve. In particular embodiments, a rocker arm may be configured to rotate about a rocker shaft.

In particular embodiments, a rocker arm assembly may comprise a first portion configured to receive a valve lift profile. By way of example and not limitation, a first portion may comprise a cam end suitably configured and/or provided in direct or indirect contact with one or more rotating cams to receive a valve lift profile. By way of example and not limitation, a first portion of the rocker arm assembly may be operatively engaged with a cam lobe of a rotating camshaft lobe, such as via rollers, tappets, pushrods, etc.

In particular embodiments, a rocker arm assembly may comprise a second portion suitably configured to operatively engage with one or more valves based on the valve lift profile received by the first portion. By way of example and not limitation, a second portion of a rocker arm assembly may comprise a valve end or portion and configured to directly or indirectly (e.g., via a valve bridge, sliding pin, swinging and/or connecting platform) interface with one or more valves of the engine.

In particular embodiments, engine valvetrains in general, and rocker arm assemblies in particular, may be configured to enable particular desirable functions of engine operation. By way of example and not limitation, particular embodiments of engine valvetrains may include an engine braking system that, when activated, can provide early and/or additional opening of an exhaust valve during an engine cycle relative to a normal (i.e., engine braking off, or drive mode) operation, thereby providing a capability to decelerate the vehicle. In particular embodiments, particular subsets of exhaust valves of an engine-braking capable valvetrain may be designated as engine braking valves. In particular embodiments, engine braking valves may be switchably engaged to perform normal exhaust valve operation (when drive mode, i.e., engine braking off mode, is engaged), or operate under specific valve timing protocols to provide engine braking (when engine braking mode is engaged).

In particular embodiments, an engine cylinder configured for engine braking may be equipped with an integrated engine braking rocker arm, wherein the rocker arm may be configured to actuate both (non-braking) exhaust valves and engine braking valves. By way of example and not limitation, an integrated engine braking rocker arm may apply an engine braking valve lift profile to engine braking valves when an engine braking mode is engaged, and apply a normal exhaust valve lift profile when in drive mode. In particular embodiments, an engine cylinder configured for engine braking may be equipped with dedicated engine braking rocker arms configured for actuating engine braking valves. In particular embodiments, a dedicated engine braking rocker arm may actuate engine braking valves only. In particular embodiments, a dedicated engine braking rocker arm may only actuate the engine braking valves when an engine braking mode is engaged.

While particular embodiments of features, combinations of features, illustrations and/or applications of rocker arm assemblies are described herein as non-limiting examples to provide a better understanding, this disclosure contemplates any suitable combinations and/or applications of features described herein. By way of example and not limitation, applications of features disclosed are not limited to engine braking applications. By way of example and not limitation, aspects of plunger assembly features disclosed herein do not require combination with actuator assemblies of any kind, and are fully contemplated as such. By way of example and not limitation, one or more features disclosed herein are contemplated in the context of both integrated rocker arm assemblies and dedicated rocker arm assemblies, as well as other suitable rocker arm configurations, in any suitable combination.

With reference to the figures,illustrates a schematic partial perspective view of an engine valvetrain assembly, according to particular embodiments.illustrates a cross-sectional enlarged view of the engine valvetrain assembly of. In particular embodiments, rocker arm assemblymay be configured to be rotatable about a rocker shaftprovided within a rocker bore. As illustrated inby way of non-limiting example, a valvetrain assemblycan include a rocker arm assemblyhaving a first portionconfigured to receive a valve lift profile. In particular embodiments, first portionmay be configured to receive a valve lift profile from a suitable assembly. By way of example and not limitation, first portionmay receive a valve lift profile from a cam, via a roller mechanism, such as illustrated in. By way of example and not limitation, first portionmay be configured to receive a valve lift profile via a pushrod mechanism (not shown).

In particular embodiments, rocker arm assemblycan comprise a second portionconfigured to operatively engage, based on the valve lift profile received by rocker arm assembly, with one or more of a plurality of valves of valvetrain assembly.

In particular embodiments, such as illustrated inby way of example and not limitation, rocker arm assemblymay be configured as a dedicated exhaust rocker arm assembly. By way of example and not limitation, in particular configurations wherein a rocker arm assemblymay be configured as a dedicated exhaust rocker arm assembly, rocker arm assemblycan be configured to operatively engage with a specific subset of exhaust valves, such as engine braking valve. By way of example and not limitation, in particular configurations wherein a rocker arm assemblymay be configured as a dedicated exhaust rocker arm, each cylinder may be additionally provided with a separate exhaust rocker arm assembly, such as exhaust rocker arm assembly, to facilitate normal non-engine braking related exhaust valve operation. By way of example and not limitation, exhaust rocker arm assemblywhere present can be configured to act on multiple exhaust valves, such as both the main exhaust valveas well as engine braking valve, via a suitable mechanism, such as a common central portionof valve bridge. In particular embodiments, rocker arm assemblymay be configured to operatively engage with engine braking valvevia a suitable mechanism, such as a swinging pin mechanism(illustrated inby way of non-limiting example), or a sliding pin(illustrated inby way of non-limiting example).

By way of example and not limitation, sliding pin, swinging pin mechanism, and/or other suitable mechanisms may be configured to permit a suitable plunger of rocker arm assemblyto engage with engine braking valvewithout affecting normal operation of main exhaust valveand/or valve bridge. In particular embodiments, sliding pin, swinging pin mechanism, and/or other suitable mechanisms may be configured to maintain valve bridgein a horizontal, parallel, and/or other desirable orientation, such as to permit a plunger of rocker arm assemblyto engage with engine braking valvewithout inadvertently applying valve lift to main exhaust valve, and/or otherwise causing undesirable friction, stress, fatigue, and/or wear on the valvetrain.

In particular embodiments, rocker arm assemblymay comprise a plunger assembly. In particular embodiments, plunger assemblymay be configured as a switchable plunger assembly. In particular embodiments, plunger assemblymay comprise a suitable plunger interface to engage with a valve interface. By way of example and not limitation, a suitable plunger interface may comprise a plunger pad. In particular embodiments, rocker arm assemblymay comprise an actuator assemblyconfigured to switchably facilitate movement of a plunger surface (e.g., extension and/or retraction between a first position and a second position), such as of plunger padof plunger assembly.

illustrates a schematic cross-sectional partial front view of an engine valvetrain assembly, with a plunger pad of a plunger assembly in a retracted position, according to particular embodiments.illustrates a schematic view of the engine valvetrain assembly of, with the plunger pad in an extend position.

illustrates a schematic cross-sectional perspective view of an exemplary plunger assembly, with a plunger pad in a retracted position, according to particular embodiments.illustrates a schematic view of the exemplary plunger assembly of, with the plunger pad in an extended position.

It will be appreciated that while particular figures may illustrate specific embodiments of plunger assemblyand/or actuator assembly, either alone, or in combination with each other, or in combination with other rocker arm and/or valvetrain assembly elements, any suitable embodiments and/or combinations are fully contemplated herein. By way of example and not limitation,may depict a different embodiment of plunger assemblyrelative to, or; such distinctions are not to read as limiting particular features, combinations, and/or applicability of any embodiment(s). By way of another non-limiting example, an embodiment of plunger assemblymay be deployed in a rocker arm assemblylacking a lost motion assembly (such as illustrated in), or it may be deployed in combination with a lost motion assembly(such as illustrated in).

In particular embodiments, plunger assemblymay comprise a selectively extendable plunger pad. In particular embodiments, plunger padmay be extendable between a retracted position (away from a valve interface) and an extended position (toward a valve interface), such as based on an actuation of actuator assembly. In particular embodiments, rocker arm assemblycan be configured so that, based on energizing and/or suitable actuation by actuator assemblywhen an engine braking mode is enabled, plunger padof plunger assemblycan extend to operatively engage with engine braking valve. In particular embodiments, in an extended position, plunger padmay be configured to be substantially stiff, i.e., to support and resist a force received from contact with a corresponding valve interface. By way of example and not limitation, plunger padin an extended position, which may correspond to an energized, or on, actuator assemblyconfiguration and an engine braking mode, may be configured to contact swinging pin mechanismor sliding pinto transfer at least a portion of a received valve lift profile to engine braking valve.

In particular embodiments, rocker arm assemblycan be configured so that, based on de-energizing and/or suitable actuation by actuator assemblywhen an engine braking mode is disabled (i.e., in engine braking off or drive mode), plunger padof plunger assemblycan retract and/or soften, collapse, and/or become compliant, so as to not exert and/or support forces relative to engine braking valve. In particular embodiments, in a retracted position, plunger padmay be configured to be substantially collapsed, soft, and/or compliant, i.e., unable support and/or resist forces due to contact with a corresponding valve interface. By way of example and not limitation, plunger padin a retracted position, which may correspond to a de-energized, or off, actuator assembly configuration and a normal or drive mode (engine braking off), may be configured to collapse under contact with swinging pin mechanismor sliding pin.

In particular embodiments, plunger assemblymay comprise an elongated member, such as shaft. In particular embodiments, plunger padmay be slidably disposed at an end of shaft. By way of example and not limitation, plunger padmay comprise a cavity, such as chamber, such that a suitably formed portion of shaftmay fit within the cavity. In particular embodiments, shaftmay be fixed in place, such as with a nut. In particular embodiments, such as illustrated by way of non-limiting example in at least, andD, andB, corresponding to a retracted position of plunger assembly, plunger padmay slide over fixed shaftaway from a valve interface. In particular embodiments, such as illustrated by way of non-limiting example in at least, corresponding to an extended position of plunger assembly, plunger padmay slide over fixed shafttoward a valve interface.

illustrates a schematic cross-sectional perspective view of a rocker arm assembly, according to particular embodiments.

In particular embodiments, plunger assemblymay comprise a plunger axis (P.A.) associated with a longitudinal axis of shaft, and/or an axis of motion of plunger pad. In particular embodiments, actuator assemblymay comprise an actuator axis (A.A.) associated with a longitudinal axis of actuator assembly. In particular embodiments, such as illustrated by way of non-limiting example in at least, a plunger axis of plunger assemblymay be angled, and/or non-parallel, to a longitudinal axis of actuator assembly. By way of example and not limitation, an actuator axis of actuator assemblymay be provided at right angles to a plunger axis of plunger assembly.

In particular embodiments, a lash adjustment mechanism may be associated with an end of the elongated member of plunger assembly. By way of example and not limitation, a lash adjustment mechanism may be associated with a second end of shaft, which may be provided opposite to a first end configured to engage and/or operatively connect with plunger pad. In particular embodiments, a first end of shaftmay be adjustable for calibration, maintenance, and/or adjustment (e.g., lash adjustment) based on temporarily loosening nutto set a desired longitudinal position of shaftwithin a bore of plunger assembly. In particular embodiments, the lash adjustment mechanism is accessible via an upper surface of the rocker arm assembly, for e.g., to facilitate lash adjustment of the plunger assembly. By way of example and not limitation, the lash adjustment mechanism may extend above the upper surface of the rocker arm assembly, e.g., for easy access and maintenance.

illustrates a schematic perspective view of a rocker arm assembly, according to particular embodiments.illustrates a schematic cross-sectional side view of the rocker arm assembly of. In particular embodiments, such as illustrated inby way of non-limiting example, rocker arm assemblymay be configured as an integrated rocker arm assembly. By way of example and not limitation, a rocker arm assemblyconfigured as an integrated rocker arm assembly may be configured to actuate multiple exhaust valves (e.g., main exhaust valveand engine braking valve) for non-engine braking exhaust valve operation, as well as selectively actuate a particular engine-braking related exhaust valve (e.g., only engine braking valve) based on engine braking valve lift protocols when engine braking mode is engaged. In particular embodiments, such as when configured as an integrated engine braking rocker arm, rocker arm assemblymay comprise a lost motion assembly.

In particular embodiments, lost motion assemblymay comprise one or more shafts, and/or a screw coupled to a shaft. By way of example and not limitation, lost motion assemblymay comprise a screwand a lost motion shaftprovided within a bore of lost motion assembly. In particular embodiments, screwmay comprise an adjustable lash screw. In particular embodiments, screwmay be coupled to a nut. In particular embodiments, lost motion assemblymay be provided with a lost motion biasing member. By way of example and not limitation, biasing membermay comprise a spring. By way of example and not limitation, biasing membermay be used to absorb at least a portion of a valve lift profile received by rocker arm assembly. In particular embodiments, lost motion shaftmay comprise a valve end configured to directly or indirectly engage with one or more valves. In particular embodiments, a valve end of lost motion shaftmay be configured to engage with a valve bridge, such as valve bridge(for e.g., a central portion). In particular embodiments, a valve end of lost motion shaftmay comprise a suitable interface, such as a plunger end, plunger pad, and/or an E-foot, e.g., E-foot.

In particular embodiments of lost motion assembly, such as depicted inas a non-limiting illustrative example, lost motion shaftmay be configured to translate along a longitudinal lost motion axis (L.M.A.) of lost motion assembly.

In particular embodiments, such as in embodiments of rocker arm assemblyconfigured as an integrated rocker arm assembly, a plunger assemblyconfigured to be switchable based on actuator assemblymay be combined with a lost motion assemblyto selectively add, subtract, and/or engage with main exhaust valveand engine braking valvebased on a received valve profile, so that a separate exhaust rocker arm assemblyis not required for exhaust valve operation. In particular embodiments, rocker arm assemblymay be configured to receive a valve lift profile (e.g., from a cam) comprising a composite valve profile. By way of example and not limitation, a composite valve profile can include a combination of valve lifts intended to operate a specific one or both of main exhaust valveand engine braking valve, based on a selected mode (e.g., engine braking or drive). In particular embodiments, a composite valve profile may comprise a normal or main exhaust valve profile as well as an engine braking valve profile.

By way of example and not limitation, such as in an exemplary integrated engine braking rocker arm, a rocker arm assemblymay receive a valve lift profile comprising a main lift section, modified approach and/or descent sections (i.e., on and off ramps) of a main lift section based on engine braking requirements, and/or one or more discrete engine braking lift sections. In particular embodiments, rocker arm assemblymay be configured so that lost motion assemblycan absorb portions of a composite valve lift profile corresponding to engine braking operation, and transfer only portions of the composite valve lift profile needed for normal exhaust valve operation (i.e., non-engine braking operation, also called drive mode). In particular embodiments, lost motion assemblymay be configured to act on valve bridgeto operate both main exhaust valveand engine braking valve. Accordingly, in particular embodiments, lost motion assemblymay be configured to receive a composite valve lift profile, absorb portions of the profile corresponding to engine braking, and impart a valve lift profile corresponding to normal exhaust valve operation to both exhaust valves. In particular embodiments, such as described herein with respect to embodiments of rocker arm assemblyconfigured as a dedicated rocker arm assembly, plunger padmay be actuated by actuator assemblyto selectively engage with engine braking valvewhen engine braking mode is enabled.

In particular embodiments, a lost motion axis of lost motion assemblymay be oriented parallel to a plunger axis of plunger assembly.

illustrates a schematic cross-sectional side view of a plunger assembly, according to particular embodiments.illustrates a schematic cross-sectional front view of the plunger assembly of.

In particular embodiments of plunger assembly, contact of plunger padwith a corresponding valve interface, such as swinging pin mechanismor sliding pin, can apply significant forces, loads, shocks, impulses, and/or wear on plunger assembly. While such contact may be needed when plunger padis extended based on energizing or switching on actuator assembly, in particular embodiments, incidental contact between plunger padand a corresponding valve interface may continue to occur when plunger padis in a collapsed or soft state based on de-energizing actuator assembly, as such embodiments may lack a positive means to sufficiently constrain, support, and/or hold plunger padin a retracted position when plunger padis collapsed or soft.

In particular embodiments of plunger assembly, such as illustrated in at least, plunger assemblymay comprise particular mechanisms to secure, constrain, support, and/or hold plunger padin a retracted position when plunger padis collapsed, or soft. In particular embodiments, such plunger securing mechanisms may be configured to release and/or permit extension of plunger padbased on actuator assembly, such as due to an extending force applied by actuator assemblywhen it is energized, or switched on.

In particular embodiments of plunger assembly, a first end of shaftconfigured to operatively engage with plunger padmay comprise a locking assembly. By way of example and not limitation, a locking assembly of plunger assemblymay comprise one or more extendable and/or protruding locking features, such as one or more lock balls. By way of example and not limitation, lock balls, or other suitable locking features, may be biased outward from the first end of shaft, and/or toward a corresponding receiving feature of plunger pad, by one or more lock biasing members.

illustrates a schematic cross-sectional side view of a plunger assembly, according to particular embodiments. By way of example and not limitation, a lock biasing member may comprise one spring(such as illustrated in the embodiment of). By way of example and not limitation, a lock biasing member may comprise multiple springs (for e.g., two springsas illustrated in the embodiment of). In particular embodiments, each of one or more lock biasing members may be disposed along a lock axis (L.A.) angled to the plunger axis (P.A.) of plunger assembly. By way of example and not limitation, such as illustrated in, a lock axis of plunger assemblymay be oriented perpendicular to the plunger axis.