EP4457430A1

EP4457430A1 - Rocker system, camshaft, and valve train for use with an internal combustion engine

Info

Publication number: EP4457430A1
Application number: EP22917436.2A
Authority: EP
Inventors: Gregory J. Mitchum; Amit Dilip THORAT; Anthony Kyle Perfetto; Girish Chandra Kura
Original assignee: Cummins Inc
Current assignee: Cummins Inc
Priority date: 2021-12-27
Filing date: 2022-12-12
Publication date: 2024-11-06
Also published as: KR20240113550A; WO2023129804A1; CN118414477A

Abstract

An internal combustion engine system includes an engine with a plurality of pistons housed in respective ones of a plurality of cylinders. A valve train is provided for opening and closing intake and exhaust valves of the cylinders during nominal engine operations. The valve train is also configured to provide for asynchronous switching between selected cam lobe lift profiles for opening and closing of the intake and/or exhaust valves.

Description

ROCKER SYSTEM, CAMSHAFT, AND VALVE TRAIN FOR USE WITH AN

INTERNAL COMBUSTION ENGINE

Cross-Reference to Related Application:

[0001] The present application claims the benefit of the filing date of U.S. Provisional Application No. 63/266,012 filed on December 27, 2021, which is incorporated herein by reference.

BACKGROUND

[0002] The present application relates to internal combustion engine systems, and more particularly, but not exclusively, relates to internal combustion engines and a rocker system, camshaft, and valve train for use therewith.

[0003] Nominal valve opening/closing, compression release braking, and other alternative valve lift operating modes can be produced by a desired cam lobe profile with the intake and/or exhaust valves of one or more engine cylinders during certain engine operating conditions. The cam lobe profile(s) produce the selected lift profile for the intake and/or exhaust valves during corresponding crank angles in order to, for example, operate with increased efficiency, provide engine braking, or produce other outcomes.

[0004] Certain systems may employ an input rocker lever that is engaged to a cam lobe with a lobe profile for producing the desired valve lift and/or opening and closing timing. The input rocker lever is selectively engaged to another rocker lever that operates the intake or exhaust valve(s) in order to link the desired cam lobe profile with the output rocker lever to produce the selected valve lift. However, if the switching of the input rocker lever into engagement with the output rocker lever is improperly timed, durability and operability issues can be presented for the switching apparatus and/or the rocker levers involved in the switching operation. Thus, there is a continuing demand for further contributions in this area of technology. SUMMARY

[0005] Certain embodiments of the present application includes unique systems, devices, methods and apparatus that operate one or more cylinders of an internal combustion engine. In an embodiment, one or more input rocker levers are selectively coupled to another rocker lever to produce a desired valve lift for one or more of the cylinders in order to output, for example, a nominal valve lift at nominal opening and closing timing, compression release braking, swirl, high lift, low lift, or other alternative valve lift and/or opening and closing timing in the corresponding cylinder.

[0006] In an embodiment, a rocker system is provided for an internal combustion engine. The internal combustion engine includes a camshaft having at least one camshaft lobe. The camshaft lobe includes a cam lobe profile with a first portion, a second portion, and a third portion. The rocker system includes at least one input rocker lever rotatable about an engine component in response to motion received from the at least one camshaft lobe. An output rocker lever is rotatable about the engine component and is configured to control opening and closing of at least one of an exhaust valve and an intake valve associated with a cylinder of the internal combustion engine. The at least one input rocker lever is rotated by the first portion of the cam lobe profile to produce a desired lift of the at least one of the exhaust valve and the intake valve while the at least one input rocker lever is coupled to the output rocker lever. The at least one input rocker is rotated by the second portion of the cam lobe profile to misalign the at least one input rocker lever with the output rocker lever to prevent coupling of the at least one input rocker lever and the output rocker lever. The at least one input rocker lever is rotated by the third portion of the cam lobe profile to align the at least one input rocker lever with the output rocker lever for coupling the at least one input rocker lever to the output rocker lever.

[0007] In an embodiment, a camshaft is provided for an internal combustion having a cylinder and at least one an intake valve and exhaust valve associated with the cylinder. The camshaft includes at least one camshaft lobe configured to control opening and closing of the at least one of the intake and exhaust valve by inducing movement of a rocker lever. The at least one camshaft lobe includes a cam lobe profile with a first portion that produces a lift to open the at least one of the exhaust valve and the intake valve through the rocker lever while the rocker lever is associated with the at least one of the exhaust valve and the intake valve. The cam lobe profile includes a second portion which misaligns the rocker lever to prevent association of the rocker lever with the at least one of the exhaust valve and the intake valve. The cam lobe profile includes a third portion which aligns the rocker lever for associating the rocker lever to the at least one of the exhaust valve and the intake valve.

[0008] In an embodiment, one of the base circle profiles has a smaller radius than the other base circle profiles. The camshaft lobes also each include a second profile portion which aligns the rocker levers during a second range of crank angle degrees to allow the coupling of the rocker levers via the switching apparatus. In an embodiment, the valve lift profiles of the two camshaft lobes also produce different valve lifts and/or valve opening and closing timing from one another.

[0009] In an embodiment, a valve train is provided for an internal combustion engine. The valve train includes one of an intake valve or an exhaust valve. The valve train includes a camshaft including a camshaft lobe, a first rocker lever movable by the camshaft lobe, and a switch apparatus for selectively coupling the first rocker lever to a second rocker lever. The camshaft lobe includes a lift profile with a first portion that lifts the one of the intake valve or exhaust valve associated with the camshaft lobe through the first rocker lever, a second portion that misaligns the first rocker lever with the second rocker lever, and a third portion which aligns the first rocker lever with the second rocker lever.

[0010] In an embodiment, a method for operating a rocker system includes aligning an input rocker lever and an output rocker lever with a camshaft lobe; coupling the aligned input rocker lever to the output rocker lever; lifting at least one of an intake valve and an exhaust valve with the output rocker lever in response to movement of the input rocker lever induced by the camshaft lobe; decoupling the input rocker lever from the output rocker lever; and misaligning the input rocker lever with the output rocker lever with the camshaft lobe to prevent coupling the input rocker lever to the output rocker lever until the input rocker lever and the output rocker lever are aligned with the camshaft lobe.

[0011] This summary is provided to introduce a selection of concepts that are further described below in the illustrative embodiments. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter. Further embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. l is a schematic view of one embodiment of an internal combustion engine system with a valve train that provides asynchronous switching of alternative valve lift profiles for at least one cylinder.

[0013] FIG. 2 is a diagrammatic and schematic view of one embodiment of a cylinder of the internal combustion engine system of FIG. 1 and a schematic of a valve actuation mechanism.

[0014] FIGs. 3 and 4 are graphical representations comparing lift profiles for the intake valves and the exhaust valves of the cylinders of the internal combustion engine system of FIG. 1 using camshaft lobes without a profile for misaligning rocker levers (FIG. 3) and with a profile for misaligning rocker levers (FIG. 4.)

[0015] FIGs. 5 and 6 are schematic views of cam lobe profiles of a camshaft for providing asynchronous switching to connect a rocker lever to another rocker lever.

[0016] FIG. 7 is a schematic of part of a valve train for providing asynchronous switching to connect a rocker lever driven by an alternative valve lift profile.

[0017] FIG. 8 is a section view of through line 8-8 of FIG. 7 showing aligned rocker levers for switching to connect a rocker lever driven by an alternative valve lift profile.

[0018] FIG. 9 is a section view similar to FIG. 8 but with the rocker levers misaligned to prevent switching to connect the rocker lever driven by the alternative valve lift profile.

[0019] FIG. 10 is a perspective view showing a valve actuation system and the intake valves and the exhaust valves of a cylinder of the internal combustion engine system of FIG. 1.

[0020] FIG. 11 is an elevation view of the valve actuation system and the intake valves and the exhaust valves of FIG. 9. [0021] FIG. 12 is a perspective of one embodiment of a rocker system of the valve actuation system of FIG. 9.

[0022] FIG. 13 is a plan view of the rocker system of FIG. 12.

[0023] FIG. 14 is an elevation view of the rocker system of FIG. 12.

[0024] FIGs. 15-17 are sectional views of the rocker system of FIG. 13 showing standard lift, cylinder deactivation, and auxiliary lift operating modes, respectively.

[0025] FIG. 18 is an elevation view of another embodiment of a rocker system for a cylinder of the internal combustion engine of FIG. 1.

[0026] FIG. 19 is a plan view of the rocker system of FIG. 18.

[0027] FIGs. 20-22 are sectional views of the rocker system of FIG. 18 showing standard lift, cylinder deactivation, and braking operating modes, respectively.

[0028] FIG. 23 is a flowchart of a procedure for operating a rocker system.

DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS

[0029] While the present invention can take many different forms, for the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications of the described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates.

[0030] With reference to FIG. 1, an internal combustion engine system 10 is shown that includes, for example, an internal combustion engine 12. Any engine type is contemplated, including compression ignition, spark-ignition, and combinations of these. The engine 12 includes a plurality of cylinders 14. FIG. 1 illustrates the plurality of cylinders 14 in an arrangement that includes six cylinders 14 in an in-line arrangement for illustration purposes only. Any number of cylinders and any arrangement of the cylinders suitable for use in an internal combustion engine 12 can be utilized. The number of cylinders 14 that can be used can range, for example, from two cylinders to eighteen or more. Furthermore, the following description at times will be in reference to one of the cylinders 14. It is to be realized that corresponding features in reference to the cylinder 14 described in FIG. 2 and at other locations herein can be present for all or a subset of the other cylinders 14 of engine 12 unless noted otherwise.

[0031] Engine 12 further includes at least one intake valve 22 and at least one exhaust valve 24 associated with each of the cylinders 14. A valve actuation system 90 is provided to open and close the intake valves 22 and/or exhaust valves 24 based on the crank angle of crankshaft 18. The valve actuation system 90 includes an engine component 570, such as a rocker shaft, about which one or more rocker levers move to control opening and closing of the intake valves 22 and/or exhaust valves 24.

[0032] As discussed further below with further reference to FIGs. 3-9, engine 12 includes a valve train 550, a rocker system 540, and/or a camshaft 520. In an embodiment, valve train 550 includes one or more intake valves 22 and/or exhaust valves 24 that are opened and closed by one or more camshaft lobes 500, 510 of camshaft 520 acting on one more rocker levers 552, 560 of rocker system 540 while the one or more rocker levers 552, 560 are associated with the intake valves 22 or exhaust valve 24.

[0033] In an embodiment, valve train 550 includes a camshaft 520, a first rocker lever 560, and one of intake valve 22 or exhaust valve 24 associated with a cylinder 14. A switch apparatus 580 selectively couples the first rocker lever 560 to a second rocker lever 5552. Camshaft 520 includes at least one camshaft lobe 510 with a lift profile having a first portion that lifts the intake valve 22 or exhaust valve 24 through the first rocker lever 560, a second portion that misaligns the first rocker lever 560 with the second rocker lever 552, and a third portion that aligns the first rocker lever 560 with the second rocker lever 552.

[0034] In an embodiment, engine 12 includes a rocker system 540 . The rocker system 540 includes an output rocker lever 552 that can be selectively coupled one or more input rocker levers 560 to control the opening and closing of the intake valve 22 or exhaust valve 24 of an associated cylinder 14. The rocker levers 552, 560 are rotatable about the engine component 570. The input rocker lever 560 rotates in response to motion received from the at least one camshaft lobe 510. The input rocker 560 is rotated by a first portion of the camshaft lobe 510 to produce a desired lift of the intake valve 22 or exhaust valve 24 while the input rocker lever 560 is coupled to the output rocker lever 552. The input rocker 560 is rotated by a second portion of the camshaft lobe 510 to misalign the input rocker lever 560 with the output rocker lever 552 to prevent coupling of the input rocker lever 560 and the output rocker lever 552. The input rocker lever 560 is rotated by a third portion of the camshaft lobe 510 to align the input rocker lever 560 with the output rocker lever 552 for coupling the input rocker lever 560 to the output rocker lever 552.

[0035] In an embodiment, the camshaft 520 includes camshaft lobes 500, 510 that are configured so the rocker levers 552, 560 are misaligned to prevent coupling of the rocker levers 552, 560 outside of a desired permitted range of crank angle degrees of the crankshaft 18. The prohibition of coupling the rocker levers 552, 560 outside the desired range of crank angle degrees prevents the switching apparatus from being able to couple rocker levers 552, 560 to one another during a valve lift event by one of the rocker levers 552, 560, which could prevent the switching apparatus from achieving a full or proper engagement with the rocker levers 552, 560 involved in the switching operation. [0036] In an embodiment, a camshaft is provided that includes camshaft lobe 510 includes a first portion 512 which misaligns the rocker lever 560 to prevent association of the rocker lever 560 with the intake valve 22 or exhaust valve 24. Camshaft lobe 510 includes a second portion 514 that produces a lift to open the intake valve 22 or exhaust valve 24 through the rocker lever 560 while the rocker lever 560 is associated with the intake valve 22 or exhaust valve 24. The camshaft lobe 510 includes a third portion 516 which aligns the rocker lever 560 for associating the rocker lever 560 to the intake valve 22 or exhaust valve 24.

[0037] Functional modes of operation that can be achieved by selectively coupling the rocker levers 552, 560 of the rocker system 540 of the present disclosure include, for example, nominal or standard intake and exhaust valve operations, Miller cycling intake valve operations, four stroke engine compression braking exhaust valve operations, cylinder deactivation for the intake and exhaust valves, two stroke engine compression braking for the intake and exhaust valves, variable swirl intake valve operation, dynamic skip fire, and/or any nominal and alternative valve lift and/or opening-closing timing operation.

[0038] One exemplary embodiment for the cylinder 14 is shown in FIG. 2, it being understood that any suitable cylinder embodiment is contemplated herein. Cylinder 14 typically houses a piston 16 that is operably attached to crankshaft 18 that is rotated by reciprocal movement of piston 16 in a combustion chamber 28 of the cylinder 14. Within a cylinder head 20 of the cylinder 14, there is at least one intake valve 22, at least one exhaust valve 24, and in certain embodiments a fuel injector 26 that provides fuel to the combustion chamber 28 formed by cylinder 14 between the piston 16 and the cylinder head 20. In other embodiments, fuel can be provided to combustion chamber 28 by port injection, or by injection in the intake system, upstream of combustion chamber 28. Furthermore, in the discussion that follows, each cylinder 14 includes two intake valves 22 and two exhaust valves 24, but such is not required in all embodiments.

[0039] The term “four stroke” herein means the following four strokes - intake, compression, power, and exhaust - that the piston 16 completes during two separate revolutions of the engine’s crankshaft 18, which is a combustion cycle occurring over 720 crank angle degrees (CAD) of rotation. A stroke begins either at top dead center (TDC) when the piston 16 is at the top of cylinder head 20 of the cylinder 14, or at bottom dead center (BDC), when the piston 16 has reached its lowest point in the cylinder 14.

[0040] Referring further to FIG. 3, there is shown example nominal or standard intake and exhaust valve opening and closing profiles during a combustion cycle for the intake valves (IV1) and the exhaust valves (EVI). During the intake stroke for IV 1, the piston 16 descends away from cylinder head 20 of the cylinder 14 to a bottom (not shown) of the cylinder, thereby reducing the pressure in the combustion chamber 28 of the cylinder 14. A combustion charge is created in the combustion chamber 28 by an intake of air through the intake valves 22 when the intake valves 22 are opened.

[0041] The fuel from the fuel injector 26 can be supplied by, for example, a high pressure common-rail system 30 (FIG. 1) that is connected to the fuel tank 32. Fuel from the fuel tank 32 is suctioned by a fuel pump (not shown) and fed to the common-rail fuel system 30. The fuel fed from the fuel pump is accumulated in the common-rail fuel system 30, and the accumulated fuel is supplied to the fuel injector 26 of each cylinder 14 through a fuel line 34. The accumulated fuel in common rail system can be pressurized to boost and control the fuel pressure of the fuel delivered to combustion chamber 28 of each cylinder 14. However, as mentioned above, any type of fuel delivery system is contemplated.

[0042] During the compression stroke in a standard or nominal mode of operation, the intake valves 22 and the exhaust valves 24 can both be closed at TDC, such as indicated by the nominal valve lift profiles for IV1 and EVI in FIGs. 3-4. The piston 16 returns toward TDC and fuel is injected near TDC in the compressed intake charge in a main injection event, and the compressed fuel-air mixture ignites in the combustion chamber 28 after a short delay. In the instance where the engine 12 is a diesel engine, this results in the combustion charge being ignited. The ignition of the air and fuel causes a rapid increase in pressure in the combustion chamber 28, which is applied to the piston 16 during its power stroke toward the BDC. Combustion phasing in combustion chamber 28 is calibrated so that the increase in pressure in combustion chamber 28 pushes piston 16, providing a net positive in the force/work/power of piston 16.

[0043] During the exhaust stroke, the piston 16 is returned toward TDC while the exhaust valves 24 are open, as shown by EVI (nominal) in FIGs. 3-4. This action discharges the burnt products of the combustion of the fuel in the combustion chamber 28 and expels the spent fuel- air mixture (exhaust gas) out through the exhaust valves 24. The next combustion cycle occurs using these same intake and exhaust valve opening closing profiles, unless an alternative valve lift condition is selected, as discussed further below.

[0044] Referring back to FIG. 1, the intake air flows through an intake passage 36 and intake manifold 38 before reaching the intake valves 22. The intake passage 36 may be connected to a compressor 41a of a turbocharger 40 and an intake throttle 42. The intake air can be purified by an air cleaner (not shown), compressed by the compressor 41 and then aspirated into the combustion chamber 28 through the intake throttle 42. The intake throttle 42 can be controlled to influence the air flow into the cylinder.

[0045] The intake passage 36 can be further provided with an optional cooler 44 that is provided downstream of the compressor 41. In one example, the cooler 44 can be a charge air cooler (CAC). In this example, the compressor 41 can increase the temperature and pressure of the intake air, while the CAC 44 can increase a charge density and provide more air to the cylinders. In another example, the cooler 44 can be a low temperature aftercooler (LTA). The CAC 44 uses air as the cooling media, while the LTA uses coolant as the cooling media.

[0046] The exhaust gas flows out from the combustion chamber 28 into an exhaust passage 46 from an exhaust manifold 48 that connects the cylinders 14 to exhaust passage 46. The exhaust passage 46 is connected to a turbine 43 and a wastegate 50 of the turbocharger 40 and then into an aftertreatment system 52. The exhaust gas that is discharged from the combustion chamber 28 drives the turbine 43 to rotate. The wastegate 50 is a device that enables part of the exhaust gas to by-pass the turbine 43 through a passageway 54. The wastegate 50 can include a control valve 56 that can be an open/closed (two position) type of valve, or a full authority valve allowing control over the amount of by-pass flow, or anything between. The exhaust passage 46 can further or alternatively include an exhaust throttle 58 for adjusting the flow of the exhaust gas through the exhaust passage 46. The exhaust gas, which can be a combination of by-passed and turbine flow, then enters the aftertreatment system 52. Other embodiments contemplate a variable inlet turbine, systems with no turbine, and/or systems with no compressor.

[0047] Optionally, a part of the exhaust gas can be recirculated into the intake system via an EGR passage (not shown.) The EGR passage can be connected the exhaust passage upstream of the turbine 43b to the intake passage 36 downstream of the intake air throttle 42. Alternatively or additionally, a low pressure EGR system (not shown) can be provided downstream of turbine 43 and upstream of compressor 41. An EGR valve can be provided for regulating the EGR flow through the EGR passage. The EGR passage can be further provided with an EGR cooler and a bypass around the EGR cooler.

[0048] The aftertreatment system 52 may include one or more devices useful for handling and/or removing material from exhaust gas that may be harmful constituents, including carbon monoxide, nitric oxide, nitrogen dioxide, hydrocarbons, and/or soot in the exhaust gas. In some examples, the aftertreatment system 52 can include at least one of a catalytic device and a particulate matter filter. The catalytic device can be a diesel oxidation catalyst (DOC) device, ammonia oxidation (AMOX) catalyst device, a selective catalytic reduction (SCR) device, three- way catalyst (TWC), lean NOX trap (LNT) etc. The reduction catalyst can include any suitable reduction catalysts, for example, a urea selective reduction catalyst. The particulate matter filter can be a diesel particulate filter (DPF), a partial flow particulate filter (PFF), etc. A PFF functions to capture the particulate matter in a portion of the flow; in contrast the entire exhaust gas volume passes through the particulate filter.

[0049] A controller 80 is provided to receive data as input from various sensors, and send command signals as output to various actuators. Some of the various sensors and actuators that may be employed are described in detail below. The controller 80 can include, for example, a processor, a memory, a clock, and an input/output (VO) interface.

[0050] The system 10 includes various sensors such as an intake manifold pressure/temperature sensor 70, an exhaust manifold pressure/temperature sensor 72, one or more aftertreatment sensors 74 (such as a differential pressure sensor, temperature sensor(s), pressure sensor(s), constituent sensor(s)), engine sensors 76 (which can detect the air/fuel ratio of the air/fuel mixture supplied to the combustion chamber, a crank angle, the rotation speed of the crankshaft, etc.), and a fuel sensor 78 to detect the fuel pressure and/or other properties of the fuel, common rail 38 and/or fuel injector 26. Any other sensors known in the art for an engine system are contemplated.

[0051] System 10 can also include various actuators for opening and closing the intake valves 22, for opening and closing the exhaust valves 24, for injecting fuel from the fuel injector 26, for opening and closing the wastegate valve 56, for the intake throttle 42, and/or for the exhaust throttle 58. Furthermore, in one embodiment, the actuators for opening and closing the intake and exhaust valves 22, 24 are provided as a part of a valve actuation (VA) system 90, such as shown schematically in FIG. 2, and include rocker levers 552, 560 that are rotated by respective camshaft lobes 500, 510 in order to produce opening and closing of the intake and exhaust valves 22, 24 at a timing determined by the camshaft lobe or lobes 500, 510 linked to the intake and exhaust valves 22, 24 via the VA system 90.

[0052] During certain operating conditions, one or more alternative valve lift profiles may be desired for one or more of the intake and exhaust valves 22, 24. For example, in FIGs. 3-4, there is shown a brake profile for EVI in which the exhaust valve is opened before top-dead-center of the power stroke and during at least a portion of the power stroke to provide compression release braking. In order to provide compression release braking, the VA system 90 can include a cam having a cam lobe profile that can be linked to the actuator(s) for opening the exhaust valve(s) 24 to provide the compression release braking opening and closing timing.

[0053] In FIG. 5, an example camshaft 500 is shown with a first cam lobe 500 that includes a base circle portion 502 and a valve lift portion 504 to provide, for example, a nominal valve lift such as shown for EVI and/or IV1 in FIGs. 3 and 4. In FIG. 6 a cam lobe 510 of camshaft 520 is shown that provides an alternative valve lift profile, such as for compression release braking as shown in FIG. 4. Cam lobe 510 is configured to misalign the rocker levers during a range of crank angle degrees in which a mis-timed actuation of the switch to couple the rocker levers 552, 560 to one another could be problematic and prevent full or complete engagement of the switch. [0054] Cam lobe 510 can be associated with to the actuator(s) for the intake and/or exhaust valves 22, 24 by VA system 90 to provide an alternative valve lift event by selectively coupling the rocker lever 560 moved by cam lobe 510 to a rocker lever that controls the opening and closing of the intake and/or exhaust valves 22, 24. Cam lobe 510 includes a cam lobe profile with a first portion 512 that is a base circle portion and a second portion 514 that is a valve lift portion. Cam lobe 510 also includes a third portion 516 that is an alignment portion between the base circle portion and valve lift portion. Cam lobe 510 may further include a transition portion 518 between second portion 514 and third portion 516 that is smaller than the third portion 516 to misalign the rocker levers, and prevent coupling of the rocker levers 552, 560 at crank angles along the second portion 514 during which the valve is lifted. [0055] Referring back to FIG. 4, the valve lifts provided by cam lobes 500, 510 are shown. The valve lift portion 504 of cam lobe 500 controls a first rocker lever 552 to produce the nominal exhaust valve opening for EVI, while the second portion 514 of cam lobe 510 controls a second rocker lever 560 to produce an exhaust valve opening event timed for compression release braking. The first portion 512 of cam lobe 510 is a smaller base circle than the base circle portion 502 of cam lobe 500 so that the rocker levers 552, 560 are misaligned along first portion 512 . When the rocker lever positioning controlled by cam lobe 510 is along the third portion 516 of cam lobe 510, the rocker levers 552, 560 are aligned and able to be coupled in order to provide the compression release braking produced by the second portion 514 in combination with the valve lift produced by valve lift portion 504. In contrast, FIG. 3 shows ant arrangement in which the base circle portions of both of the cam lobes controlling the nominal exhaust valve opening and closing and the compression release braking opening and closing are the same size such that there is no mis-alignment of the rocker levers except when the rocker levers are controlled by the respective valve lift portions.

[0056] FIG. 7 shows an embodiment of valve actuation system 90 with a valve train 550. Valve train 550 includes first rocker lever 552 and second rocker lever 560 movable by a camshaft 520. First rocker lever 552 is controlled by cam lobe 500 for movement about a component 570 such as a rocker shaft, and second rocker lever 560 is controlled by cam lobe 510 for movement about component 570. Alternatively first rocker lever 552 can be an output rocker lever and coupled to one or more other input rocker levers that are directly linked to associated cam lobes along camshaft 520.

[0057] A switch apparatus 580 includes a switch 582 housed in one of the rocker levers 552, 560, such as rocker lever 560, that is movable to selectively couple or connect the rocker lever 560 to the rocker lever 552. For example, in FIG. 8 the rocker levers 552, 560 are shown in alignment with one another so that switch 582 can be moved into an aligned passage 554 of rocker lever 552, as shown by the position 582a of switch 582. Switch 582 can include, for example, one or more pins that are moved into and/or out of passage 554 in order to couple and decouple the rocker levers 552, 560.

[0058] The alignment between rocker levers 552, 560 occurs only while the rocker lever 560 position is controlled by the third portion 516 of cam lobe 510. When rocker lever 560 is controlled by the base circle along first portion 512, the rocker lever 560 is misaligned with rocker lever 552, such as shown in FIG. 9. This misalignment prevents the switch 582 from being movable into the passage 554 of rocker lever 552, since the passage 554 is not aligned with the switch 582.

[0059] In an embodiment, a method 600 for operating a rocker system 540 is contemplated, as shown in the flowchart FIG. 23. The method 600 can include, for example, aligning 602 an input rocker lever 560 and an output rocker lever 552 with a cam lobe 510. The aligning can include, for example, positioning the input rocker lever 560 at a predetermined orientation with output rocker lever 552 using third portion 516 of camshaft lobe 510 to allow switching apparatus 580 to couple the rocker levers 552, 560 to one another. The aligned input rocker lever 560 is then coupled to the output rocker lever 552 at 604 using, for example, switching apparatus 580. The method 600 can further includes lifting 606 at least one of an intake valve 22 and an exhaust valve 24 with the output rocker lever 552 in response to movement of the input rocker lever 560 induced by the camshaft lobe 510. For example, the movement of rocker lever 560 that lifts intake valve 22 or exhaust valve 24 via rocker lever 552 can be the rotation of the rocker lever 560 about the engine component 570, such as the rocker shaft, due to the third portion 516 of camshaft lobe 510 acting on the rocker lever 560.

[0060] The input rocker lever 560 can then be decoupled at 608 from the output rocker lever 552. In an embodiment, the decoupling can include disengaging or disconnecting a switch, such as switch apparatus 580 discussed above. The input rocker lever 560 is then misaligned at 610 with the output rocker lever 552 with the camshaft lobe 510 to prevent coupling the input rocker lever 560 to the output rocker lever 552 until the input rocker lever 560 and the output rocker lever 552 are aligned with the camshaft lobe 510. In an embodiment, misaligning the rocker levers 552, 560 includes rotating rocker lever 560 with first portion 512 of camshaft lobe 510 to a misaligned position relative to rocker lever 552 to prevent the switching apparatus 580 from being able to engage the rocker lever 560 to rocker lever 552.

[0061] Referring to FIGs. 10-17, further details regarding an embodiment of VA system 90 is shown that is applicable to provide cylinder deactivation of one or more of the cylinders 14 under cylinder deactivation conditions and/or an alternative lift profile for the intake and/or exhaust valve(s) of the one or more cylinders 14, in addition to the standard lift profile discussed above. FIGs. 10-11 show a first VA system 90a for the intake side and a second VA system 90b for the exhaust side, which may be collectively and individually referred to herein as VA system 90. The VA system 90 can be provided for operation of one or both of the intake valves 22, for operation of one or both of the exhaust valves 24, for operation of one of the intake valves 22 and one of the exhaust valves 24, or for operation of all of the intake and exhaust valves 22, 24. In addition, the first VA system 90a can provide one or more lift profiles for the intake valves 22 that differ from the one or more lift profiles for the exhaust valves 24.

[0062] Specifically, the first VA system 90a includes a first rocker system 100a that is configured to engage the lobes of the intake side camshaft 92 along one of more of the cylinders 14. Alternatively or additionally, the second VA system 90b may include a same, similar, or different second rocker system 100b that is configured to engage the lobes of the exhaust side camshaft 94 along one of more of the cylinders 14. The first and second rocker systems 100a, 100b may be individually or collectively referred to as rocker system 100 herein.

[0063] In the illustrated embodiment, intake side camshaft 92 includes three camshaft lobes 93a, 93b, 93c (generically referred to as cam shaft lobes 93) that provide at least two different valve lift profiles for the intake valves 22, and exhaust side camshaft 94 includes three camshaft lobes 95a, 95b, 95c (generically referred to as camshaft lobes 95) that provide at least two different valve lift profiles for the exhaust valves 24. Other embodiments contemplate only two lobes 93, 95, or more than three lobes 93, 95, on one or both of the camshafts 92, 94. The three camshaft lobes 93, 95 of the respective camshaft in the illustrated embodiment may provide, for example, a nominal or standard lift profile for the associated valve(s) 22, 22 and one or more auxiliary lift profiles for the associated valve(s) 22, 24 that differs from the standard lift profile in height and/or timing of the valve lift from its respective valve seat. In addition, at least one of the camshaft lobes 93, 95 may include a cam lobe profile like cam lobe 510 discussed above to misalign the associated rocker lever during a first range of crank angle degrees to prevent the rocker lever from being coupled to another rocker lever, and to align the associated rocker lever for coupling with another rocker lever during a second range of crank angle degrees before the valve lift.

[0064] Referring further to FIGs. 12-14, the rocker system 100 includes an output rocker lever 102 and at least one input rocker lever. In the illustrated embodiment, the rocker system 100 includes a first input rocker lever 104, a second input rocker lever 106, and a third input rocker lever 108 that are each rotatably mounted to an engine component, such as a rocker shaft 120, in side-by-side relation. First input rocker lever 104 includes a first roller 110 that is contact with the corresponding camshaft lobe 93a, 95a. Second input rocker lever 106 includes a second roller 112 that is contact with the corresponding camshaft lobe 93b, 95b. Third input rocker lever 108 includes a third roller 114 that is contact with the corresponding camshaft lobe 93c, 95c. As discussed further below, one or more of the input rocker levers 104, 106, 108 is selectively connectable with the output rocker lever 102 to transfer motion from the respective camshaft lobe(s) 93, 95 to the connected one(s) of the intake valves 22 or exhaust valves 24. In addition, the input rocker levers 104, 106, 108 can be disconnected from the output rocker lever 102 so that no valve lift is provided during cylinder deactivation.

[0065] A biasing mechanism 122 includes springs 124, 126, 128 that are each in contact with output rocker lever 102 and with respective ones the input rocker levers 104, 106, 108 to bias the corresponding rollers 110, 112, 114 into contact with the respective camshaft lobes 93, 95. Hydraulic lash adjusters 130, 132 also illustrated that are connected to respective arms 102a, 102b of the output rocker lever 102 and also to the corresponding ones of the intake valves 22 or exhaust valves 24. Biasing mechanism 122 is located on a side of rocker system 100 opposite hydraulic lash adjusters 130, 132 in the illustrated embodiment, although such is not required. In another embodiment, an adjusting screw or elephant foot may be provided in lieu of or in addition to hydraulic lash adjusters 130, 132. A rocker pedestal 134 may also be provided for mounting to the cylinder head, but embodiments without a rocker pedestal 134 are also contemplated. In addition, embodiments without a rocker shaft 120 are contemplated, with the rocker levers being mountable about any suitable engine component, such as an end-pivot integrated into the cylinder head to which the rocker lever(s) are mounted.

[0066] The rocker system 100 can include a first valve lift switch 150 for selectively connecting or coupling and disconnecting or decoupling first input rocker lever 104 to output rocker lever 102 to transfer motion from or prevent the transfer of motion from the associated camshaft lobe 93a, 95a to the connected ones of the intake and/or exhaust valves 22, 24. The rocker system 100 can also include a second valve lift switch 200 for selectively connecting and disconnecting one or both of second and third input rocker levers 106, 108 to output rocker lever 102 to transfer motion from or prevent the transfer of motion from the associated camshaft lobes 93b, 95b, 93c, 95c to the connected ones of the intake and/or exhaust valves 22, 24. As discussed above, one or more of the camshaft lobes 93, 95 can include a lobe profile with a third portion 516 that aligns the associated rocker lever 104, 106, 108 for actuation of the switch 150 and/or switch 200, and a differently sized base circle along first portion 512 that misaligns the associated rocker lever 104, 106, 108 to prevent actuation of switch 150 and/or switch 200.

[0067] Referring further to FIGs. 15-17, first valve lift switch 150 is housed in a bore 152 that extends in and from output rocker lever 102 to first input rocker lever 104. First switch 150 includes a first valve lift pin assembly 154 that includes a spring-biased first valve lift pin 156 comprising multiple shear pin parts 170, 172, 174 in abutting, end-to-end engagement. First valve lift pin 156 is normally biased via springs 158a, 158b to an engaged position such that first input rocker lever 104 is connected to output rocker lever 102, as shown in FIG. 15. In the engaged position, the valve lift pin 156 spans the joints 160, 162 between the rocker levers 102, 104, forming shear interfaces 160a, 162a at joints 160, 162. The engaged position of first valve lift switch 150 is used during operating conditions in which the standard or nominal lift for the intake or exhaust valves 22, 24 is desired from the camshaft lobes 92a, 94a.

[0068] In order to disconnect or decouple rocker levers 102, 104 from one another, hydraulic fluid pressure is supplied into bore 152 from the rocker shaft 120 of engine 12 via the hydraulic system of engine 12 through opening 166, and into the space 164 at one end of bore 152. The hydraulic pressure displaces valve lift pin 156 into contact with base 168, compressing springs 158a, 158b, as shown in FIG. 16 and FIG. 17. In this condition, the junction between shear pin parts 170, 172 is aligned with joint 160, and the junction between shear pin parts 172, 174 is aligned with joint 162. This disengaged position removes the shear interfaces 160a, 162a since no part of first valve lift pin 156 spans the joints 160, 162. As a result, rotation of the first input rocker lever 104 is not transferred to output rocker lever 102, and the motion imparted by the camshaft lobes 93a, 95a is not transferred to the intake or exhaust valves 22, 24 but rather is taken up by the bias spring 124. The disengaged position for first valve lift switch 150 is used during operating conditions in which cylinder deactivation is desired, and/or during which an alternate lift profile from the second and third input rockers 106, 108 is desired from camshaft lobes 93b, 95b, 93c, 95c. [0069] Second valve lift switch 200 is housed in a bore 202 that extends in and from output rocker lever 102, to second input rocker lever 106, and to third input rocker lever 108. Second valve lift switch 200 includes a second valve lift pin assembly 204 that includes a second valve lift pin 206 comprising multiple shear pin parts 220, 222 in abutting, end-to-end engagement. Second valve lift pin 206 is normally biased via spring 208 to a disengaged position, as shown in FIGs. 15 and 16.

[0070] In the engaged position shown in FIG. 17, the second input rocker lever 106 and third input rocker lever 108 are connected to output rocker lever 102. In the engaged position, the valve lift pin 206 spans the joints 210, 212 between the rocker levers 102, 106, 108, forming shear interfaces 210a, 212a at joints 210, 212. The engaged position of second valve lift switch 200 is used during operating conditions in which the alternative lift for the intake or exhaust valves 22, 24 is desired from the camshaft lobes 93b, 95b, 93c, 95c via the input rocker levers 106, 108. In order to connect or couple rocker levers 102, 106, 108 to one another, hydraulic fluid pressure is supplied into bore 202 from rocker shaft 120 of engine 12 via the hydraulic system of engine 12 through an opening 216, and into the control pressure space 214 at one end of bore 202. The hydraulic fluid pressure displaces valve lift pin 206 into contact with base 218, compressing spring 208, as shown in FIG. 17.

[0071] In the disengaged condition of FIGs. 15 and 16, the junction between shear pin parts 220, 222 is aligned with joint 210, and the end of shear pin part 222 is located within output rocker lever 102 so that shear pin part 222 does not span joint 212. This disengaged position removes the shear interfaces 210a, 212a since no part of second valve lift pin 206 spans the joints 210, 212. As a result, rotation of the second and third input rocker levers 106, 108 are not transferred to output rocker lever 102, and the motion imparted by the camshaft lobes 93b, 95b, 93c, 95c is not transferred to the intake or exhaust valves 22, 24 but rather taken up by bias springs 126, 128. The disengaged position for second valve lift switch 200 is used during operating conditions in which cylinder deactivation is desired, or during which only a nominal or standard lift profile from the first input rocker 104 is desired from camshaft lobes 93a, 95a.

[0072] FIGs. 18-22 illustrate another embodiment rocker system 300. Rocker system 300 can be similar to rocker system 100 discussed above, and the discussion that follows is directed to features of rocker system 300 that differ from rocker system 100. One or more aspects or features of rocker system 100 discussed above can be provided for rocker system 300, and vice versa.

[0073] Referring to FIGs. 18-19, rocker system 300 includes an output rocker lever 302, a first input rocker lever 304, a second input rocker lever 306, and a third input rocker lever 308 that are each rotatably mountable to an engine component, such as rocker shaft 120. First input rocker lever 304 includes a first roller 310 for contact with the corresponding camshaft lobe 93 a, 95a. Second input rocker lever 306 includes a second roller 312 for contact with the corresponding camshaft lobe 93b, 95b. Third input rocker lever 308 includes a third roller 314 that is contact with the corresponding camshaft lobe 93c, 95c. One or more of the input rocker levers 304, 306, 308 is selectively connectable with the output rocker lever 302 to transfer motion from the respective camshaft lobe(s) 93, 95 to the connected one(s) of the intake valves 22 or exhaust valves 24. In addition, the input rocker levers 304, 306, 308 can be disconnected from the output rocker lever 302 so that no valve lift is provided during cylinder deactivation. [0074] A biasing mechanism 322 includes springs 324, 326, 328 that are each in contact with output rocker lever 302 and a respective one of the input rocker levers 304, 306, 308 to bias the corresponding rollers 310, 312, 314 into contact with the respective camshaft lobes. Biasing mechanism 322 differs from biasing mechanism 122 in that the spring 324 for the first input rocker lever 304 is provided on the same side of the rocker assembly as the hydraulic lash adjusters 330, 332. Hydraulic lash adjusters 330, 332 are connected to respective arms 302a, 302b of the output rocker lever 302 and the corresponding ones of the intake valves 22 or exhaust valves 24.

[0075] The rocker system 300 includes a first valve lift switch 350 for selectively connecting and disconnecting first input rocker lever 304 to output rocker lever 302 to transfer motion from or prevent the transfer of motion from the associated camshaft lobe 93a, 95a to the connected ones of the intake and/or exhaust valves 22, 24. The rocker system 300 also includes a second valve lift switch 400 for selectively connecting and disconnecting one or both of second and third input rocker levers 306, 308 to output rocker lever 302 to transfer motion or prevent the transfer of motion from the associated camshaft lobes 93b, 95b, 93c, 95c to the connected ones of the intake and/or exhaust valves 22, 24. As discussed above, one or more of the camshaft lobes 93, 95 can include a lobe profile with a third portion 516 that aligns the associated rocker lever 304, 306, 308 for actuation of the switch 350 and/or switch 400, and a differently sized base circle along first portion 512 that misaligns the associated rocker lever 304, 306, 308 to prevent actuation of switch 350 and/or switch 400.

[0076] Referring further to FIGs. 20-22, first valve lift switch 350 is housed in a bore 352 that extends in and from output rocker lever 302 to first input rocker lever 304. First valve lift switch 350 includes a first valve lift pin assembly 354 that includes a first valve lift pin 356 comprising multiple shear pin parts 370, 372 normally biased away from one another via spring 358 to an engaged position such that first input rocker lever 304 is connected to output rocker lever 302, as shown in FIG. 20. In the engaged position, the valve lift pin 356 spans the joints 360, 362 between the rocker levers 302, 304, forming shear interfaces 360a, 362a at joints 360, 362. The engaged position of first switch 150 is used during operating conditions in which the standard or nominal lift for the intake or exhaust valves 22, 24 is desired from the camshaft lobes 93a, 95a. [0077] In order to disconnect or decouple rocker levers 302, 304 from one another, hydraulic fluid pressure is supplied into bore 352 from rocker shaft 120 of the engine 12 via the hydraulic system of engine 12 through openings 366a, 366b, and into the spaces 364a, 364b at the opposite ends of bore 352. The hydraulic fluid pressure displaces shear pin parts 370, 372 toward one another by compressing spring 358, as shown in FIG. 21 and FIG. 22. In this condition, the shear pin parts 370, 372 are moved entirely into first input rocker lever 304. This disengaged position removes the shear interfaces 160a, 162a since no part of first valve lift pin 356 spans the joints 360, 362. As a result, rotation of the first input rocker lever 304 is not transferred to output rocker lever 302, and the motion imparted by the camshaft lobes 93a, 95a is not transferred to the intake or exhaust valves 22, 24. The disengaged position for first valve lift switch 350 is used during operating conditions in which cylinder deactivation is desired, or during which an alternate lift profile from the second and third input rockers 306, 308 is desired from camshaft lobes 93b, 95b, 93c, 95c.

[0078] Second valve lift switch 400 is housed in a bore 402 in output rocker lever 302, second input rocker lever 306, and third input rocker lever 308. Second valve lift switch 400 includes a second valve lift pin assembly 404 that includes a second valve lift pin 406 comprising multiple shear pin parts 420, 422 in bore 402. Shear pin part 420 and shear pin part 422 are normally biased toward one another via springs 408, 409 and against a central base 418 in bore 402 to a disengaged position, as shown in FIGs. 20 and 21.

[0079] In the engaged position shown in FIG. 22, the second input rocker lever 306 and third input rocker lever 308 are connected to output rocker lever 302. In the engaged position, the shear pin parts 420, 422 of shear pin 406 span the joints 410, 412 between the rocker levers 302, 306, 308, forming shear interfaces 410a, 412a at joints 410, 412. The engaged position of second valve lift switch 400 is used during operating conditions in which the alternative lift for the intake or exhaust valves 22, 24 is desired from the camshaft lobes 93b, 95b, 93c, 95c via the input rocker levers 306, 308. In order to connect or couple rocker levers 302, 306, 308 to one another, hydraulic fluid pressure is supplied into bore 402 from the rocker shaft 120 of engine 12 via the hydraulic system of engine 12 through opening 416, and into the control pressure space 414 of bore 402 between shear pin parts 420, 422. The hydraulic fluid pressure displaces shear pin parts 420, 422 off of base 418, compressing springs 408, 409 so that the shear pin parts span joints 410, 412, as shown in FIG. 22.

[0080] In the disengaged condition, the shear pin parts 420, 422 are located within output rocker lever 302 so that shear pin parts 420, 422 do not span joints 410, 412. This disengaged position removes the shear interfaces 410a, 412a since no part of second valve lift pin 406 spans the joints 410, 412. As a result, rotation of the second and third input rocker levers 306, 308 is not transferred to output rocker lever 302, and the motion imparted by the camshaft lobes 93b, 95b, 93c, 95c is not transferred to the intake or exhaust valves 22, 24. The disengaged position for second valve lift switch 400 is used during operating conditions in which cylinder deactivation is desired, or during which a nominal or standard lift profile from the first input rocker lever 304 is desired from camshaft lobes 93a, 95a.

[0081] The rocker systems 100, 300 disclosed herein can allow multiple modes of operation to be provided at the intake and/or exhaust valve for one or more cylinders 14 of engine 12 using a single hydraulic actuator. The modes of operation can include, for example, a standard lift profile, no lift for cylinder deactivation, and an alternate lift profile. The alternate lift profile can be to provide, for example, engine braking, such as four stroke compression braking or two stroke compression braking. An example two stoke compression braking valve lift profile for the intake and exhaust valves is shown in FIG. 3 with IV2 and EV2. Other alternative lift profiles are also contemplated other than those for compression braking.

[0082] Valve actuation assemblies can be easily upgraded with using the rocker systems of the present disclosure. For example, the valve actuation system can be upgraded from a standard lift function for the intake and exhaust valves to include cylinder deactivation or four stroke compression braking. The valve actuation system can also be upgraded from a standard lift function for the intake and exhaust valves to include cylinder deactivation and four stroke compression braking. The valve actuation system can also be upgraded from a standard lift function for the intake and exhaust valves to include cylinder deactivation and two stroke compression braking.

[0083] During operation of the internal combustion engine system 10, the controller 80 can receive information from the various sensors listed above through VO interface(s), process the received information using a processor based on an algorithm stored in a memory of the controller 80, and then send command signals to the various actuators through the I/O interface. For example, the controller 80 can receive information regarding cylinder deactivation condition, an engine braking request, a vehicle or engine speed request, a combustion condition, an aftertreatment temperature condition, and/or an engine load condition. The controller 80 is configured to process the conditions and/or requests, and then based on the control strategy, send one or more command signals to one or more actuators to provide cylinder deactivation and/or an alternate valve lift profile using the associated camshaft lobes and input rocker levers.

[0084] The controller 80 can be configured to implement the disclosed cylinder deactivation and alternative valve lift strategies using VA system 90. In one embodiment, the disclosed method and/or controller configuration include the controller 80 providing a cylinder deactivation command or an alternate valve lift command in response to a cylinder deactivation condition or an engine operating condition that is based on one or more signals from one or more of the plurality of sensors described above for internal combustion engine system 10. The cylinder deactivation and alternative valve lift commands control VA mechanism 90 to switch the camshaft lobes for input to provide the desired intake and exhaust valve closure or opening and closing lift profile and/or timing. [0085] The control procedures implemented by the controller 80 can be executed by a processor of controller 80 executing program instructions (algorithms) stored in the memory of the controller 80. The descriptions herein can be implemented with internal combustion engine system 10. In certain embodiments, the internal combustion engine system 10 further includes a controller 80 structured or configured to perform certain operations to control internal combustion engine system 10 in achieving one or more target conditions. In certain embodiments, the controller forms a portion of a processing subsystem including one or more computing devices having memory, processing, and communication hardware. The controller may be a single device or a distributed device, and the functions of the controller 80 may be performed by hardware and/or by instructions encoded on a computer readable medium.

[0086] In certain embodiments, the controller 80 includes one or more modules structured to functionally execute the operations of the controller. The description herein including modules emphasizes the structural independence of the aspects of the controller, and illustrates one grouping of operations and responsibilities of the controller. Other groupings that execute similar overall operations are understood within the scope of the present application. Modules may be implemented in hardware and/or software on a non-transient computer readable storage medium, and modules may be distributed across various hardware or other computer components.

[0087] Certain operations described herein include operations to interpret or determine one or more parameters. Interpreting or determining, as utilized herein, includes receiving values by any method known in the art, including at least receiving values from a datalink or network communication, receiving an electronic signal (e.g. a voltage, frequency, current, or PWM signal) indicative of the value, receiving a software parameter indicative of the value, reading the value from a memory location on a non-transient computer readable storage medium, receiving the value as a run-time parameter by any means known in the art, and/or by receiving a value by which the interpreted or determined parameter can be calculated, and/or by referencing a default value that is interpreted or determined to be the parameter value.

[0088] Various aspects of the present disclosure are contemplated as described herein. According to one aspect, a rocker system is disclosed for an internal combustion engine having a camshaft with at least one camshaft lobe, and the at least one camshaft lobe includes a cam lobe profile with a first portion, a second portion, and a third portion. The rocker system includes at least one input rocker lever rotatable about an engine component in response to motion received from the at least one camshaft lobe, and an output rocker lever rotatable about the engine component. The output rocker lever can be selectively coupled to the at least one input rocker lever to control opening and closing of at least one of an exhaust valve and an intake valve associated with a cylinder of the internal combustion engine. The at least one input rocker is rotated by the first portion of the cam lobe profile to produce a desired lift of the at least one of the exhaust valve and the intake valve while the at least one input rocker lever is coupled to the output rocker lever. The at least one input rocker is rotated by the second portion of the cam lobe profile to misalign the at least one input rocker lever with the output rocker lever to prevent coupling of the at least one input rocker lever and the output rocker lever. The at least one input rocker lever is rotated by the third portion of the cam lobe profile to align the at least one input rocker lever with the output rocker lever for coupling the at least one input rocker lever to the output rocker lever.

[0089] In an embodiment, the at least one input rocker lever is aligned with the output rocker lever for switching engagement with the output rocker lever over a first range of crank angle degrees of a crankshaft of the internal combustion engine.

[0090] In a further embodiment, the at least one input rocker is misaligned with the output rocker to prevent switching engagement with the output rocker lever over a second range of crank angle degrees of the crankshaft of the internal combustion engine. In another further embodiment, the output rocker lever controls opening and closing of the at least one of the exhaust valve and the intake valve while in switching engagement with the input rocker lever.

[0091] In an embodiment, the rocker system includes at least one valve lift switch for coupling the at least one input rocker lever to the output rocker lever when the at least one input rocker is aligned with the output rocker to transfer motion from the first portion of the at least one camshaft lobe to the at least one of the exhaust valve and the intake valve.

[0092] In a further embodiment, the at least one input rocker lever includes a first input rocker lever, and the rocker system includes a second input rocker lever, and the first and second input rocker levers are each rotatable about the engine component in response to motion received from respective ones of a first camshaft lobe and a second camshaft lobe of the camshaft. [0093] In yet a further embodiment, the at least one valve lift switch includes at least one pin that is movable to selectively couple each of the first and second input rocker levers to the output rocker lever. In yet a further embodiment, the at least one valve lift switch includes a first pin that is movable to selectively couple the first input rocker lever to the output rocker lever and a second pin that is movable to selectively the second input rocker lever to the output rocker lever. [0094] According to another aspect of the present disclosure, a camshaft for an internal combustion engine is provided. The engine has a cylinder and at least one of an intake valve and an exhaust valve associated with the cylinder. The camshaft includes at least one camshaft lobe configured to control an opening and closing timing of the at least one of the exhaust valve and the intake valve by the at least one cam shaft lobe inducing movement of a rocker lever. The at least one camshaft lobe includes a cam lobe profile including a first portion, a second portion, and a third portion. The first portion produces a lift to open the at least one of the exhaust valve and the intake valve through the rocker lever while the rocker lever is associated with the at least one of the exhaust valve and the intake valve. The second portion misaligns the rocker lever to prevent association of the rocker lever with the at least one of the exhaust valve and the intake valve. The third portion aligns the rocker lever for associating the rocker lever to the at least one of the exhaust valve and the intake valve.

[0095] In an embodiment, the third portion of the cam lobe profile is a constant lift profile that lifts the rocker lever over a first range of crank angle degrees of a crankshaft of the internal combustion engine.

[0096] In a further embodiment, the second portion of the cam lobe profile is a base circle profile extends from the first portion of the cam lobe profile to the third portion of the cam lobe profile. In another further embodiment, the third portion of the cam lobe profile is connected to the first portion of the cam lobe profile with a transition portion that is smaller in size than the constant lift profile.

[0097] According to another aspect of the disclosure, a valve train for an internal combustion engine is provided. The valve train includes one of an intake valve or exhaust valve, a camshaft including a camshaft lob, a first rocker lever movable by the camshaft lobe, and a switch apparatus for selectively coupling the first rocker lever to a second rocker lever. The camshaft lobe includes a lift profile with a first portion that lifts the one of the intake valve or exhaust valve associated with the camshaft lobe through the first rocker lever, a second portion that misaligns the first rocker lever with the second rocker lever, and a third portion that aligns the first rocker lever with the second rocker lever.

[0098] In an embodiment, the second at least one other rocker lever is an output rocker lever connected to the one of the intake valve or exhaust valve.

[0099] In an embodiment, the second rocker lever is moved by a second camshaft lobe. The second camshaft lobe includes a second lift profile that lifts the one of the intake valve or exhaust valve when associated with the second camshaft lobe through the second rocker lever, and the second camshaft lobe includes a base circle portion that is a same size as the third portion of the camshaft lobe.

[0100] In an embodiment, the second portion of the lift profile of the camshaft lobe misaligns the switch apparatus to prevent coupling of the first rocker lever with the second rocker lever.

[0101] In an embodiment, the second portion of the lift profile of the camshaft lobe aligns the switch apparatus to couple of the first rocker lever with the second rocker lever.

[0102] In an embodiment, the switch apparatus includes at least one pin that is housed in one of the first and second rocker levers when the first and second rocker levers are not coupled to one another. In a further embodiment, the at least one pin spans between the first rocker lever and the second rocker lever when the first and second rocker levers are coupled to one another.

[0103] Another aspect of the present disclosure includes a method for operating a rocker system. The method includes aligning an input rocker lever and an output rocker lever with a camshaft lobe; coupling the aligned input rocker lever to the output rocker lever; lifting at least one of an intake valve and an exhaust valve with the output rocker lever in response to movement of the input rocker lever induced by the camshaft lobe; decoupling the input rocker lever from the output rocker lever; and misaligning the input rocker lever with the output rocker lever with the camshaft lobe to prevent coupling the input rocker lever to the output rocker lever until the input rocker lever and the output rocker lever are aligned with the camshaft lobe.

[0104] While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only certain exemplary embodiments have been shown and described. Those skilled in the art will appreciate that many modifications are possible in the example embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims.

[0105] In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary.

Claims

What is claimed is:

1. A rocker system for an internal combustion engine having a camshaft with at least one camshaft lobe, the at least one camshaft lobe including a cam lobe profile with a first portion, a second portion, and a third portion, the rocker system comprising: at least one input rocker lever rotatable about an engine component in response to motion received from the at least one camshaft lobe; and an output rocker lever rotatable about the engine component, and the output rocker lever can be selectively coupled to the at least one input rocker lever to control opening and closing of at least one of an exhaust valve and an intake valve associated with a cylinder of the internal combustion engine, the at least one input rocker is rotated by the first portion of the cam lobe profile to produce a desired lift of the at least one of the exhaust valve and the intake valve while the at least one input rocker lever is coupled to the output rocker lever, wherein the at least one input rocker is rotated by the second portion of the cam lobe profile to misalign the at least one input rocker lever with the output rocker lever to prevent coupling of the at least one input rocker lever and the output rocker lever, and the at least one input rocker lever is rotated by the third portion of the cam lobe profile to align the at least one input rocker lever with the output rocker lever for coupling the at least one input rocker lever to the output rocker lever.

2. The rocker system of claim 1, wherein the at least one input rocker lever is aligned with the output rocker lever for switching engagement with the output rocker lever over a first range of crank angle degrees of a crankshaft of the internal combustion engine.

3. The rocker system of claim 2, wherein the at least one input rocker is misaligned with the output rocker to prevent switching engagement with the output rocker lever over a second range of crank angle degrees of the crankshaft of the internal combustion engine.

4. The rocker system of claim 2, wherein the output rocker lever controls opening and closing of the at least one of the exhaust valve and the intake valve while in switching engagement with the input rocker lever.

29

5. The rocker system of claim 1, further comprising at least one valve lift switch for coupling the at least one input rocker lever to the output rocker lever when the at least one input rocker is aligned with the output rocker to transfer motion from the first portion of the at least one camshaft lobe to the at least one of the exhaust valve and the intake valve.

6. The rocker system of claim 5, wherein the at least one input rocker lever includes a first input rocker lever, the rocker system further comprising a second input rocker lever, and the first and second input rocker levers are each rotatable about the engine component in response to motion received from respective ones of a first camshaft lobe and a second camshaft lobe of the camshaft.

7. The rocker system of claim 6, wherein the at least one valve lift switch includes at least one pin that is movable to selectively couple each of the first and second input rocker levers to the output rocker lever.

8. The rocker system of claim 6, wherein the at least one valve lift switch includes a first pin that is movable to selectively couple the first input rocker lever to the output rocker lever and a second pin that is movable to selectively the second input rocker lever to the output rocker lever.

9. A camshaft for an internal combustion engine having a cylinder and at least one of an intake valve and an exhaust valve associated with the cylinder, the camshaft comprising: at least one camshaft lobe configured to control an opening and closing timing of the at least one of the exhaust valve and the intake valve by the at least one cam shaft lobe inducing movement of a rocker lever, the at least one camshaft lobe including a cam lobe profile including: a first portion that produces a lift to open the at least one of the exhaust valve and the intake valve through the rocker lever while the rocker lever is associated with the at least one of the exhaust valve and the intake valve; a second portion which misaligns the rocker lever to prevent association of the rocker lever with the at least one of the exhaust valve and the intake valve; and

30 a third portion which aligns the rocker lever for associating the rocker lever to the at least one of the exhaust valve and the intake valve.

10. The camshaft of claim 9, wherein the third portion of the cam lobe profile is a constant lift profile that lifts the rocker lever over a first range of crank angle degrees of a crankshaft of the internal combustion engine.

11. The camshaft of claim 10, wherein the second portion of the cam lobe profile is a base circle profile extends from the first portion of the cam lobe profile to the third portion of the cam lobe profile.

12. The camshaft of claim 10, wherein the third portion of the cam lobe profile is connected to the first portion of the cam lobe profile with a transition portion that is smaller in size than the constant lift profile.

13. A valve train for an internal combustion engine, the valve train comprising: one of an intake valve or exhaust valve; a camshaft including a camshaft lobe; a first rocker lever movable by the camshaft lobe; and a switch apparatus for selectively coupling the first rocker lever to a second rocker lever, wherein the camshaft lobe includes a lift profile with a first portion that lifts the one of the intake valve or exhaust valve associated with the camshaft lobe through the first rocker lever, a second portion that misaligns the first rocker lever with the second rocker lever, and a third portion that aligns the first rocker lever with the second rocker lever.

14. The valve train of claim 13, wherein the second at least one other rocker lever is an output rocker lever connected to the one of the intake valve or exhaust valve.

15. The valve train of claim 13, wherein the second rocker lever is moved by a second camshaft lobe, wherein the second camshaft lobe includes a second lift profile that lifts the one of the intake valve or exhaust valve when associated with the second camshaft lobe through the second rocker lever, and the second camshaft lobe includes a base circle portion that is a same size as the third portion of the camshaft lobe.

16. The valve train of claim 13, wherein the second portion of the lift profile of the camshaft lobe misaligns the switch apparatus to prevent coupling of the first rocker lever with the second rocker lever.

17. The valve train of claim 13, wherein the second portion of the lift profile of the camshaft lobe aligns the switch apparatus to couple of the first rocker lever with the second rocker lever.

18. The valve train of claim 13, wherein the switch apparatus includes at least one pin that is housed in one of the first and second rocker levers when the first and second rocker levers are not coupled to one another.

19. The valve train of claim 18, wherein the at least one pin spans between the first rocker lever and the second rocker lever when the first and second rocker levers are coupled to one another.

20. A method for operating a rocker system, the method comprising: aligning an input rocker lever and an output rocker lever with a camshaft lobe; coupling the aligned input rocker lever to the output rocker lever; lifting at least one of an intake valve and an exhaust valve with the output rocker lever in response to movement of the input rocker lever induced by the camshaft lobe; decoupling the input rocker lever from the output rocker lever; and misaligning the input rocker lever with the output rocker lever with the camshaft lobe to prevent coupling the input rocker lever to the output rocker lever until the input rocker lever and the output rocker lever are aligned with the camshaft lobe.