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EP-3775508-B1 - SYSTEMS AND METHODS FOR IEGR USING SECONDARY INTAKE VALVE MOTION AND LOST-MOTION RESET

EP3775508B1EP 3775508 B1EP3775508 B1EP 3775508B1EP-3775508-B1

Inventors

  • BALTRUCKI, Justin, D.
  • SCHWOERER, JOHN, A.

Dates

Publication Date
20260506
Application Date
20190326

Claims (18)

  1. A system for actuating at least one (396) of two or more engine valves to provide exhaust gas recirculation in an internal combustion engine, the system comprising; an exhaust valvetrain (350) for conveying motion to at least one exhaust valve; an intake valve motion source (394); an intake valvetrain (390, 300) for conveying motion from the intake valve motion source to at least one intake valve, the intake valvetrain including an intake rocker (300); a lost motion component (320) in the intake valvetrain for selectively absorbing motion in the intake valvetrain; a control fluid circuit (330) in communication with the lost motion component; the system being further characterized by : the intake rocker including a reset component (340) for resetting the control fluid circuit; and a reset trigger (360) for triggering the reset component, the reset trigger being cooperatively associated with the exhaust valvetrain, the reset component being adapted to collapse the lost motion component at an appropriate time in an engine cycle to complete a secondary lift event (242, 410) in the at least one intake valve at a time near a start or end of a main exhaust event motion (210) of the at least one exhaust valve and to thereby facilitate exhaust gas recirculation in the internal combustion engine.
  2. The system of claim 1, wherein the exhaust valvetrain is an exhaust rocker, wherein the reset trigger is disposed on the exhaust rocker.
  3. The system of claim 1, wherein the reset component is disposed at least partially within the intake rocker, and wherein the reset trigger is arranged to be engaged by the reset component as a result of motion of the intake rocker.
  4. The system of any of claims 1 to 3, wherein the reset component comprises a poppet valve (344).
  5. The system of any of claims 1 to 4, wherein the reset component comprises a triggered vent.
  6. The system of any of claims 1 to 5, wherein the reset component is adapted to reduce pressure in the control fluid circuit.
  7. The system of any of claims 1 to 6, wherein at least one of the reset trigger and the reset component is adapted to be adjusted to set reset to correspond with a specific valve lift height.
  8. The system of any of claims 1 to 7, wherein the lost motion component is disposed on a valve side of the intake rocker in the intake valvetrain.
  9. The system of any of claims 1 to 7, wherein the lost motion component is disposed on a cam side of the intake rocker in the intake valvetrain.
  10. The system of any of claims 1 to 9, wherein the lost motion component comprises a piston (324) disposed in a bore (322) in the intake rocker in the intake valvetrain.
  11. The system of claim 10, wherein the lost motion component further comprises a biasing spring (336).
  12. The system of claims 10 or 11, wherein the control fluid circuit communicates with the bore in the intake rocker.
  13. The system of any of claims 1 to 12, wherein the intake valvetrain comprises an overhead rocker.
  14. A method of providing exhaust gas recirculation in an internal combustion engine, the internal combustion engine comprising an exhaust valvetrain (350) for conveying motion to at least one exhaust valve (396); an intake valve motion source (394); an intake valvetrain (390, 300) for conveying motion from the intake valve motion source to at least one intake valve; a lost motion component (320) in the intake valvetrain for selectively absorbing motion in the intake valvetrain; a control fluid circuit (330) in communication with the lost motion component; the intake valvetrain including an intake rocker (300), the intake rocker including a reset component (340) for resetting the control fluid circuit; and a reset trigger (360) cooperatively associated with the exhaust valvetrain, for triggering the reset component, the method comprising: opening the at least one exhaust valve during a main exhaust event (210) of an internal combustion engine power cycle; the method being further characterized by : resetting the reset component with the reset trigger at an appropriate time in the internal combustion engine power cycle to collapse the lost motion component, thereby ending opening of the at least one intake valve to complete a secondary lift event (242, 410) during the at least one exhaust valve opening to facilitate internal exhaust gas recirculation in the internal combustion engine.
  15. The method of claim 14, further comprising a step of triggering the reset component in response to motion of the intake rocker.
  16. The method of claim 14, wherein the exhaust valvetrain further comprises an exhaust rocker, the method further comprising a step of triggering the reset component by motion of the exhaust rocker.
  17. The method of claim 14, further comprising a step of resetting the control fluid circuit using a poppet valve (344).
  18. The method of claim 14, further comprising a step of adjusting at least one of the reset component or the reset trigger to correspond with a specific valve lift height.

Description

FIELD This disclosure relates generally to systems and methods for managing combustion engine emissions and controlling exhaust gas recirculation. More particularly, this disclosure relates to systems and methods for internal exhaust gas recirculation, including systems and methods for actuating one or more engine valves to facilitate the flow of residual exhaust gases from the intake or exhaust manifold into the combustion chamber. BACKGROUND Internal combustion engines rely on valve actuation systems to control engine intake and exhaust valves, which in turn, control the flow of combustion components and products into and out of combustion chambers during operation. In a four-stroke operating cycle, intake valves are opened to admit fuel and air into an expanding combustion chamber during an intake stroke of a piston moving within a cylinder. In a compression stroke, the intake valves are closed and combustion components are compressed by the piston. The compressed combustion components are then ignited, causing a power stroke of the piston. In an exhaust stroke, exhaust valves are opened to allow combustion products to escape the cylinder as the piston is displaced therein. This operation is typically called a "positive power" operation of the engine and the motions applied to the valves during positive power operation are typically referred to as "main event" valve actuation motions. In addition to main event actuation, engine valve actuation systems may include features that facilitate auxiliary valve actuation motion to support functions such as engine braking (power absorbing), exhaust gas recirculation (EGR) and others. Such valve motion may be accomplished using "auxiliary" events imparted to one or more of the engine valves. Valve movement is typically controlled by one or more rotating cams as motion sources. Cam followers, push rods, rocker arms and other elements, which may form a valvetrain, provide for direct transfer of motion from the cam surface to the valves. For auxiliary events, "lost motion" devices or variable length actuators may be utilized in the valvetrain to facilitate auxiliary event valve movement. Lost motion devices refer to a class of technical solutions in which valve motion is modified compared to the motion that would otherwise occur as a result of actuation by a respective cam surface alone. Lost motion devices may include devices whose length, rigidity or compressibility is varied and controlled in order to facilitate the selective occurrence of auxiliary events in addition to, or as an alternative to, main event operation of valves. EGR systems typically provide for a portion of exhaust gases to flow back into the engine combustion chamber during positive power operation. The presence of residual exhaust gases in the combustion chamber during combustion typically reduces the concentration of nitrogen oxide (NOx) in engine emissions overall and may provide other benefits in engine operation. An external EGR (EEGR) system may route exhaust gases back to the combustion chamber by way of one or more external passages that communicate with the exhaust manifold or other part of the exhaust system. An internal EGR system (iEGR) typically provides for the introduction of exhaust gases into the combustion chamber without the use of external conduits, for example, by providing appropriate motion to one or more engine valves at the appropriate time during the engine cycle. Such systems may provide for recirculation of exhaust gases using a secondary opening of an intake valve during an exhaust event in a four-stroke engine cycle and/or the secondary opening of an exhaust valve during the intake portion of a four-stroke engine cycle. As is described in the SAE Technical Paper 98010, 1998, titled "The Potential of a Combined Miller Cycle and Internal EGR Engine of Future Heavy Duty Truck Applications" by Edwards, S., Frankle, G., Wirbeleit, F., and Raab, A., ("Edwards et al.") the residual percentage of exhaust gas can be controlled with secondary exhaust valve lift events and secondary intake valve lift events. This publication describes and graphically illustrates variation of in-cylinder and port pressures in the engine operating cycle as a function of crankshaft angle. Three potential stages in the engine operating cycle are identified as presenting opportunities for iEGR. The publication further describes prior art results of secondary exhaust valve lift profiles and secondary intake valve lift profiles on residual exhaust gas percentage. From these results, it is known that an additional intake event timed near the beginning of exhaust valve opening can provide EGR level percentages that are equivalent to using an exhaust opening event during the intake. US 2014/238324 Al and US 2005/211206 Al disclose valve actuation systems producing auxiliary valve events for engine braking or exhaust gas recirculation. Thus, two viable methods for iEGR include a secondary intake valve "bu