US-20260125995-A1 - VALVETRAIN SYSTEMS FOR CYLINDER DEACTIVATION WITH RECHARGING AND METHODS THEREOF

US20260125995A1US 20260125995 A1US20260125995 A1US 20260125995A1US-20260125995-A1

Abstract

A rocker arm assembly operable in a cylinder deactivation mode includes a valve portion, a drive cam portion, and a recharge cam portion. The valve portion is configured to operatively engage with one or more valves of a cylinder. The drive cam portion comprises a switchable lost motion mechanism that is configured to selectively absorb or transfer motion from a drive cam to the valve portion. The recharge cam portion is configured to be coupled to the valve portion.

Inventors

Tomas Bilek
Alessandro Roscioli
Vladimír BALHÁREK

Assignees

EATON INTELLIGENT POWER LIMITED

Dates

Publication Date: 20260507
Application Date: 20251229

Claims (20)

1 . A rocker arm assembly of a valvetrain operable in a cylinder deactivation mode, the rocker arm assembly comprising: a valve portion configured to operatively engage with one or more valves of a cylinder; a drive cam portion configured to operatively engage with a drive cam associated with a drive cam lift profile, the drive cam portion comprising a switchable lost motion mechanism configured to selectively absorb motion from the drive cam or transfer motion from the drive cam to the valve portion; and a recharge cam portion configured to be rotatably coupled to the valve portion; wherein when the cylinder deactivation mode is enabled, the switchable lost motion mechanism is configured to absorb motion from the drive cam to deactivate the cylinder, and the recharge cam portion is configured to operatively engage with a recharge cam associated with a recharge valve lift profile and transfer motion from the recharge cam to the valve portion to permit balancing pressure within the deactivated cylinder.
2 . The rocker arm assembly of claim 1 , wherein a transfer of motion from the drive cam to the valve portion causes one or more of the valves to move.
3 . The rocker arm assembly of claim 1 , wherein a transfer of motion from the drive cam to the valve portion causes one or more of the valves to move according to the drive lift profile associated with the drive cam.
4 . The rocker arm assembly of claim 1 , wherein the drive valve lift profile comprises a plurality of drive valve lift displacements over an engine cycle and the recharge valve lift profile comprises a plurality of recharge valve lift displacements over the engine cycle such that each drive valve lift displacement is greater than or equal to each corresponding recharge valve lift displacement over the engine cycle.
5 . The rocker arm assembly of claim 1 , wherein when the cylinder deactivation mode is disabled, the switchable lost motion mechanism transfers motion from the drive cam to the valve portion.
6 . The rocker arm assembly of claim 5 , wherein when the cylinder deactivation mode is disabled, the recharge cam portion receives motion from the recharge cam corresponding to a base circle valve lift of the recharge cam or the recharge cam portion disengages from the recharge cam for one or more portions of the engine cycle.
7 . The rocker arm assembly of claim 1 , wherein the switchable lost motion mechanism comprises a latch mechanism comprising a latch bore and one or more latch pins.
8 . The rocker arm assembly of claim 7 , further comprising a lost motion spring.
9 . The rocker arm assembly of claim 7 , wherein the one or more latch pins are hydraulically or electrically actuated to selectively decouple the drive cam portion from rotating with the valve portion about a rocker shaft.
10 . The rocker arm assembly of claim 7 , wherein the drive cam portion comprises a drive roller configured to receive the drive valve lift profile and the recharge cam portion comprises a recharge roller configured to receive the recharge valve lift profile, wherein the latch bore of the latch mechanism is at least partially disposed in the drive roller.
11 . The rocker arm assembly of claim 1 , wherein the recharge cam portion is rigidly coupled to the valve portion to rotate as an integral unit about a rocker shaft.
12 . A method of operating a valvetrain comprising, when a cylinder deactivation mode of the valvetrain is enabled, absorbing, by a switchable lost motion mechanism of a rocker arm assembly of the valvetrain, motion received from a drive cam by a drive cam portion of the rocker arm assembly to deactivate a cylinder associated with the valvetrain, the drive cam associated with a drive cam lift profile; and transferring, by a recharge cam portion of the rocker arm assembly to a valve portion of the rocker arm assembly, motion received from a recharge cam by the recharge cam portion to open one or more valves associated with the cylinder to permit balancing pressure within the deactivated cylinder, the recharge cam associated with a recharge valve lift profile, wherein the switchable lost motion mechanism is configured to selectively absorb motion from the drive cam or transfer motion from the drive cam to the valve portion.
13 . The method of claim 12 , further comprising, when the cylinder deactivation mode is disabled, transferring, by the switchable lost motion mechanism, motion from the drive cam to the valve portion of the rocker arm assembly.
14 . The method of claim 13 , further wherein the drive valve lift profile comprises a plurality of drive valve lift displacements over an engine cycle and the recharge valve lift profile comprises a plurality of recharge valve lift displacements over the engine cycle such that each drive valve lift displacement is greater than or equal to each corresponding recharge valve lift displacement over the engine cycle.
15 . The method of claim 14 , further comprising, when the cylinder deactivation mode is disabled, receiving, by the recharge cam portion, motion from the recharge cam corresponding to a base circle valve lift of the recharge cam; or disengaging the recharge cam portion from the recharge cam for one or more portions of the engine cycle.
16 . A valvetrain system comprising: a cylinder configured to be selectively deactivated; one or more valves associated with the cylinder; a drive cam and a recharge cam associated with the one or more valves; a rocker shaft; a rocker arm assembly configured to be rotatable about the rocker shaft, the rocker arm assembly comprising: a valve portion configured to operatively engage with the one or more valves; a drive cam portion configured to operatively engage with a drive cam associated with a drive cam lift profile, the drive cam portion comprising a switchable lost motion mechanism configured to selectively absorb motion from the drive cam or transfer motion from the drive cam to the valve portion; and a recharge cam portion configured to be rotatably coupled to the valve portion; wherein when an cylinder deactivation mode is enabled, the switchable lost motion mechanism is configured to absorb motion from the drive cam to deactivate the cylinder, and the recharge cam portion is configured to operatively engage with a recharge cam associated with a recharge valve lift profile and transfer motion from the recharge cam to the valve portion to permit balancing pressure within the deactivated cylinder.
17 . The valvetrain system of claim 16 , wherein the drive valve lift profile comprises a plurality of drive valve lift displacements over an engine cycle and the recharge valve lift profile comprises a plurality of recharge valve lift displacements over the engine cycle such that each drive valve lift displacement is greater than or equal to each corresponding recharge valve lift displacement over the engine cycle.
18 . The valvetrain system of claim 17 , wherein when the cylinder deactivation mode is disabled, the switchable lost motion mechanism transfers motion from the drive cam to the valve portion.
19 . The valvetrain system of claim 18 , wherein when the cylinder deactivation mode is disabled, the recharge cam portion receives motion from the recharge cam corresponding to a base circle valve lift of the recharge cam or the recharge cam portion disengages from the recharge cam for one or more portions of the engine cycle.
20 . The valvetrain system as in any of claims 16 , wherein the switchable lost motion mechanism comprises a latch mechanism comprising a latch bore and one or more latch pins, the valvetrain system further comprising a lost motion spring.

Description

PRIORITY This application claims the benefit under 35 U.S. C. § 365(c) of International Patent Application No. PCT/IB2024/058058, filed 19 Aug. 2024, which claims the benefit under 35 U.S. C. § 119(e) of U.S. Provisional Ser. No. 63/520,540 , filed 18 Aug. 2023, which is incorporated herein by reference. TECHNICAL FIELD This disclosure generally relates to engine valvetrain systems, and more particularly to valvetrains with switchable rocker arms. BACKGROUND Cylinder deactivation (CDA) in engines can provide benefits such as improved overall efficiencies, fuel economy, and aftertreatment performance at low loads. Valvetrain systems can be adapted to selectively deactivate one or more cylinders in an engine based on preventing motion of the intake and/or exhaust valves of the corresponding cylinders. However, CDA methodologies based on by shutting off valve motion may incur particular disadvantages for engine performance. For example, a lack of cylinder pressure management authority in CDA mode may be associated with harmful low gas temperatures, lubrication system contamination, and/or reduced emission control. It can therefore be desirable to provide systems and methods for improving cylinder pressure management in CDA mode. SUMMARY OF PARTICULAR EMBODIMENTS The present disclosure relates to features that can enable and improve performance relating to valvetrains with switchable rocker arms. By way of example and not limitation, particular disclosed embodiments describe systems and methods to allow recharging and/or balancing of cylinder pressure for deactivated cylinders in cylinder deactivation (CDA) applications of valvetrains. In particular embodiments, recharging and/or balancing of cylinder pressure can be accomplished by implementing one or more valve opening events for one or more intake and/or exhaust valves of the deactivated cylinder. In particular embodiments, a rocker arm assembly of a valvetrain operable in a cylinder deactivation mode is disclosed, the rocker arm assembly including: a valve portion configured to operatively engage with one or more valves of a cylinder; a drive cam portion configured to operatively engage with a drive cam associated with a drive cam lift profile, the drive cam portion including a switchable lost motion mechanism configured to selectively absorb motion from the drive cam or transfer motion from the drive cam to the valve portion; and a recharge cam portion configured to be rotatably coupled to the valve portion; wherein when the cylinder deactivation mode is enabled, the switchable lost motion mechanism is configured to absorb motion from the drive cam to deactivate the cylinder, and the recharge cam portion is configured to operatively engage with a recharge cam associated with a recharge valve lift profile and transfer motion from the recharge cam to the valve portion to permit balancing pressure within the deactivated cylinder. In particular embodiments, which may combine the features of some or all of the above embodiments, a transfer of motion from the drive cam to the valve portion causes one or more of the valves to move. In particular embodiments, which may combine the features of some or all of the above embodiments, a transfer of motion from the drive cam to the valve portion causes one or more of the valves to move according to the drive lift profile associated with the drive cam. In particular embodiments, which may combine the features of some or all of the above embodiments, the drive valve lift profile includes a plurality of drive valve lift displacements over an engine cycle and the recharge valve lift profile includes a plurality of recharge valve lift displacements over the engine cycle such that each drive valve lift displacement is greater than or equal to each corresponding recharge valve lift displacement over the engine cycle. In particular embodiments, when the cylinder deactivation mode is disabled, the switchable lost motion mechanism transfers motion from the drive cam to the valve portion. In particular embodiments, which may combine the features of some or all of the above embodiments, when the cylinder deactivation mode is disabled, the recharge cam portion receives motion from the recharge cam corresponding to a base circle valve lift of the recharge cam or the recharge cam portion disengages from the recharge cam for one or more portions of the engine cycle. In particular embodiments, which may combine the features of some or all of the above embodiments, the switchable lost motion mechanism includes a latch mechanism including a latch bore and one or more latch pins. In particular embodiments, which may combine the features of some or all of the above embodiments, the rocker arm assembly includes a lost motion spring. In particular embodiments, which may combine the features of some or all of the above embodiments, the one or more latch pins are hydraulically or electrically actuated to selectively decouple the drive cam porti