Cross-Reference to Related Application:

[0001] The present application claims the benefit of the filing date of U.S. Provisional

Application No. 62/045,661 filed on September 4, 2014, which is incorporated herein by reference.

FIELD OF FNVENTION

[0002] This invention relates to an internal combustion engine with multiple cylinders, and more particularly to cylinder deactivation of one or more of the multiple cylinders.

BACKGROUND

[0003] The cylinders in an internal combustion engine can be disabled in order to reduce fuel consumption. This may be accomplished by cutting off the supply of fuel to selected cylinders, particularly to save fuel under light engine load conditions. This increases the load on the other cylinders and provides some pumping loss reduction, but still requires pumping work to move the air flow through all the cylinders.

[0004] Another method of cylinder disablement includes disabling or maintaining the intake and exhaust valves of the cylinder in a closed condition, which further reduces pumping work over simply providing a fuel cutoff to the deactivated cylinders. It is desirable with these methods to trap charge air in the deactivated cylinder so the trapped charge air provides an air spring to minimize losses with the piston moving up and down in the combustion chamber. A small amount of charge air is lost during each engine cycle so the amount of charge air in the cylinder reduces over time. After a certain period of time, the charge air pressure in the deactivated cylinder is below atmospheric pressure during some parts of the cycle, allowing an undesirable buildup of oil from the crankcase into the deactivated cylinder.

[0005] In order to maintain an amount of charge air in the cylinder that prevents oil buildup in the crankcase, prior techniques re-activate the valves of deactivated cylinder to refill the reactivated cylinders with charge air. However, this approach involves pumping work and a fuel economy penalty. In addition, there is noise and vibration associated with transitioning between the deactivated and activated conditions. Therefore, further improvements in cylinder deactivation systems and techniques are needed.

SUMMARY

[0006] One embodiment is a unique system that includes a multi-cylinder internal combustion engine configured to control deactivation of at least one cylinder of the multiple cylinders. In one embodiment, the engine includes an exhaust system with an exhaust emission after-treatment device for treatment of exhaust gases from the cylinders, an air supply system for supplying a charge flow to the cylinders, and a fuel supply system for supplying fuel to each cylinder. A controller is configured to switch a valve actuation mechanism of the engine between at least two fixed non-zero valve lift profiles to control the opening and closing of the intake valve(s) of the deactivated cylinder(s) in response to the presence or absence of a cylinder deactivation condition.

[0007] In the nominal non-deactivated operation condition, each of the multiple cylinders are operated on a first fixed non-zero lift profile that opens the intake and exhaust valves to receive and combust a charge flow and to discharge exhaust gases according to any suitable valve opening and closing timing arrangement for a non-deactivated cylinder. In response to a deactivation condition indicated by engine operation conditions, the valve actuation mechanism is switched to a deactivation profile for at least one of the cylinders. The deactivation profile includes a second non-zero valve lift profile that is nearly a base circle but includes a small duration, low lift portion for the intake valve near bottom dead center (BDC) of the intake stroke of the deactivated cylinder to equalize cylinder pressure and intake manifold pressure. The exhaust valve(s) of the deactivated cylinder(s) simultaneously operates with a zero lift profile and therefore remains closed during cylinder deactivation. Accordingly, there is no need to temporarily re-activate the deactivated cylinders during a deactivation condition to prevent oil build-up in the crank case and/or deactivated cylinders.

[0008] 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

[0009] Fig. 1 A is a schematic depiction of a system having an internal combustion engine.

[0010] Fig. IB is a schematic depiction of the system of Fig. 1A with another embodiment internal combustion engine.

[0011] Fig. 2 is a schematic cross-section of a deactivation cylinder and valve actuation mechanism.

[0012] Fig. 3 is a graph of intake valve lift profiles for nominal and cylinder deactivation operating conditions.

[0013] Fig. 4 is a flow diagram of a procedure for deactivating one or more cylinders of an internal combustion engine.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0014] For the purposes 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 in the illustrated embodiments, and any further applications of the principles of the invention as illustrated therein as would normally occur to one skilled in the art to which the invention relates are contemplated herein.

[0015] Referencing Fig. 1A, a system 100 is depicted having an engine 102. The engine 102 is an internal combustion engine of any type, and can include a stoichiometric engine, a diesel engine, a gasoline engine, an ethanol engine, and/or a natural gas engine. In certain

embodiments, the engine 102 includes a lean combustion engine such as a lean burn gasoline engine, or a diesel cycle engine. In certain embodiments, the engine 102 may be any engine type producing emissions that may include an exhaust gas recirculation (EGR) system, for example to reduce NO _x emissions from the engine 102. The engine 102 includes a number of cylinders 103a, 103b (collectively referred to as cylinders 103.) The number of cylinders 103 may be any number suitable for an engine.

[0016] In the illustrated embodiment of Fig. 1A, the system 100 includes an engine 102 having an inline 4 cylinder arrangement for illustration purposes, but V-shaped arrangements and other cylinder numbers are also contemplated. For example, the embodiment in Fig. IB includes a system 100' with another embodiment engine 102' that includes inline 6 cylinder arrangement. The discussion herein with respect to engine 102 also applies to engine 102' and system 100' unless specifically noted otherwise. In Fig. IB, the intake, exhaust and controller systems are omitted for brevity and clarity.

[0017] The engine 102 includes nominal cylinders 103 a which are operated with a nominal valve lift profile under both nominal and cylinder deactivation operating conditions, and one or more deactivation cylinders 103b which are operated with a deactivation valve lift profile in response to cylinder deactivation conditions being present. The deactivation cylinders 103b can be operated with the nominal valve lift profile when cylinder deactivation conditions are not present. In the illustrated embodiment of Fig. 1A, two cylinders of engine 102 are deactivation cylinders 103b, but more or fewer than two cylinders can be deactivation cylinders. In the illustrated embodiment of Fig. IB, three cylinders of engine 102' are deactivation cylinders 103b' and three cylinders 103a' are nominal cylinders, but more or fewer than three cylinders can be deactivation cylinders. In addition, the cylinders identified as nominal and deactivation cylinders in Figs. 1 A and IB can be in any order.

[0018] A typical multi-cylinder engine 102 has an engine block 200 with multiple cylinders 103, and, as shown in Fig. 2, a piston 202 in each cylinder that is operably attached to a crankshaft 204. There is also at least one intake valve 206 and at least one exhaust valve 208 that allow passage of air into and out of each cylinder 103. A combustion chamber 210 is formed inside each cylinder. The typical engine 102 operates on a four-stroke cycle that sequentially includes an air intake stroke, a compression stroke, a power stroke, and an exhaust stroke. As used herein, one cycle of the cylinder or engine occurs at the completion of these four strokes.

[0019] When cylinders are deactivated, the opening mechanism of prior art valve actuation mechanisms is collapsed so the intake and exhaust valves of the deactivated cylinders remain in a completely closed condition during cylinder deactivation. In addition, fuel delivery to the deactivated cylinders is stopped. The active cylinders are then operated with a greater amount of air and fuel to meet the engine power demands. The active cylinders thus operate with a greater air flow, reducing pumping losses, and improved fuel efficiency. However, due to imperfect sealing of the piston rings for the deactivated cylinders, the amount of charge air trapped in the combustion chamber reduces during each deactivation cycle. When this pressure drop results in a cylinder pressure that is less than atmospheric, oil build-up can occur in the deactivated cylinders.

[0020] The present system 100 includes a valve actuation mechanism 220 that is configured to provide a first non-zero lift profile for opening and closing intake valve 206 of each cylinder 103 in response to nominal engine operation conditions. The exhaust valve(s) of each cylinder can also be opened and closed with a non-zero valve lift profile that is the same or different from that of the non-zero-valve lift profile that opens and closes the intake valves 206. As shown in Fig. 2, valve actuation mechanism 220 is further configured for switching to a second non-zero valve lift profile for operation of intake valves 206 of deactivation cylinders 103b in response to a cylinder deactivation condition where cylinders 103b are deactivated. The exhaust valves 208 of deactivation cylinders 103b are operated with a zero lift profile in response to cylinder deactivation conditions. A cylinder deactivation condition can be determined in response to one or more engine operating conditions, such as a low engine load and/or low engine speed.

[0021] Valve actuation mechanism 220 includes hardware mounted in a head 212 of engine 102 and control algorithms that are internal to the controller 140. The cylinder deactivation hardware includes a valve opening mechanism 214, 216 for respective ones of intake and exhaust valves 206, 208 of each cylinder 103. The valve actuation mechanism 220 also comprises a hydraulic subsystem (not shown) that supplies pressurized oil from an engine oil pump (not shown) to each valve opening mechanism 214, 216. In one embodiment, the valve opening mechanism 214, 216 is comprised of a lifter and a locking pin mechanism that is inserted between the camshaft 222, 224 and the respective valves 206, 208.

[0022] A typical valve train is comprised of the camshafts 222, 224, or in another embodiment a single cam shaft.) The plurality of valves 206, 208 are normally closed to a zero lift position against their respective valve seats and are spring-mounted in the head 212. The valve train is operable to open the plurality of exhaust valves 208, the plurality of intake valves 206, or both, depending upon the engine design. Each camshaft 222, 224 is a long rod that is mounted in the engine 102 and rotates around its longitudinal axis. Each camshaft 222, 224 has cam lobes 226, 228, respectively, that correspond to and operate each valve 206, 208. Cam lobes 226, 228 are typically cut into the respective camshaft 222, 224 such that they are eccentric to the axis of rotation of the respective camshaft 222, 224.

[0023] Each lobe 226, 228 has an eccentric portion and a portion that is concentric to the longitudinal axis of the cam shaft. The concentric portion is defined by and can be referred to as the cam base circle, and the eccentric portion projects from the base circle to define a non-zero- lift profile to open and close the respective valve 206, 208 for a specified lift and duration from its valve seat. For example, the intake valve cam lobe 226 can define a non-zero lift profile 300 as shown in Fig. 3. Each lobe 226, 228 is in physical contact with a respective one of the valve opening mechanisms 214, 216, which are each comprised of a lifter and a locking pin mechanism. The valve opening mechanisms 214, 216 are in physical contact with a respective one of the valves 206, 208. The rotation of the camshaft 222, 224 causes respective valve 206, 208 to open according to the non-zero lift profile defined by the corresponding lobe 226, 228 when the position of the respective camshaft 222, 224 is such that the eccentric portion of its corresponding lobe 226, 228 is in contact with the adjacent valve opening mechanism 214, 216.

[0024] For deactivation cylinders 103b, such as shown in Fig. 2, the valve actuation mechanism 220 is operable to substantially disable each intake valve 206, completely disable each exhaust valve 208, and completely disable each fuel injector 162 for each cylinder 103b that is to be deactivated in response to a cylinder deactivation condition. In one embodiment, the valve actuation mechanism 220 disables half of the cylinders 103 when in the deactivation mode. In a specific embodiment, camshaft 222 is switchable to place a second cam lobe 226' to operate the intake valves 206 of each of the deactivation cylinders 103b with a second non-zero lift profile defined by second cam lobe 226' that includes a second non-zero valve lift profile 302 (Fig. 3) that defines a low lift, short duration profile for opening intake valve 206 of the deactivation cylinder(s) 103b during cylinder deactivation conditions. Camshaft 224 associated with the exhaust valves 208 is also switchable from a third non-zero lift profile defined by a third cam lobe 228 to a fourth profile at a fourth cam lobe 228' that defines a cam base circle/zero lift profile that maintains the respective exhaust valve 208 at each deactivation cylinder 103b in a closed position against its valve seat in response to cylinder deactivation conditions.

[0025] In a specific embodiment, Fig. 3 shows a nominal or first non-zero intake valve lift profile 300 for nominal cylinders 103a and, during non-deactivation conditions, for deactivation cylinders 103b. The exhaust valves of the cylinders 103 are opened and closed with any suitable non-zero valve lift profile that may be the same or different from profile 300. Under deactivation conditions, deactivation cylinders 103b operate with a second non-zero lift profile 302 that includes a short duration and a low lift for intake valve(s) 206 of the deactivated cylinder(s) while nominal cylinders 103 a continue to operate with the first non-zero valve lift profile 300. The exhaust valve(s) 208 of the deactivation cylinder(s) 103b operate with a zero lift profile during the deactivation condition.

[0026] In a specific embodiment, the second non-zero lift profile 302 includes a peak lift amount between 0.25 and 2 millimeters and a lift duration between 20 and 80 crank angle degrees that encompasses bottom dead center of the intake stroke of the piston of the corresponding deactivation cylinder 103b. The lift amount is the distance the intake valve 206 is spaced from its respective valve seat. The remaining portion of the second non-zero lift profile 302 follows the cam base circle so the intake valve 206 remains closed. In another embodiment, the low lift profile 302 obtains a peak lift 302a at a different crank angle than a crank angle at which a peak lift 300a of the nominal or first non-zero valve lift profile 300 is obtained.

[0027] Referring back to Fig. 1A, in the system 100 exhaust flow 134 produced by cylinders 103 is provided to an exhaust manifold 130 and outlet to an exhaust passage 132. System 100 may include and exhaust gas recirculation (EGR) passage 109 to provide an EGR flow 108 that combines with an intake flow 118 at a position upstream of an intake manifold 105. Intake manifold 105 provides a charge flow including the intake flow 118 and, if provided, with EGR flow 108 to cylinders 103. Intake manifold 105 is connected to an intake passage 104 that includes an intake throttle 107 to regulate the charge flow to cylinders 103. Intake passage 104 may also include a charge air cooler (not shown) to cool the charge flow provided to intake manifold 105. Intake passage 104 may also include an optional compressor 170 to compress the intake air flow received from an intake air cleaner (not shown.)

[0028] The EGR flow 108 may combine with the intake flow 118 at an outlet of EGR passage 109, at a mixer, or by any other arrangement. In certain embodiments, the EGR flow 108 returns to the intake manifold 105 directly. In the illustrated embodiment, EGR flow 108 mixes with the intake flow 118 downstream of throttle 107 so that exhaust pressure on cylinders 103 is closely aligned with intake pressure, which reduces pumping losses through cylinders 103. In other embodiments, EGR passage 109 can include an EGR cooler (not shown) and a bypass (not shown) with a valve that selectively allows EGR flow to bypass the EGR cooler. The presence of an EGR cooler and/or an EGR cooler bypass is optional and non-limiting. [0029] Cylinders 103 are connected to an exhaust system that includes an exhaust manifold 130 that receives exhaust gases in the form of exhaust flow 134 from cylinders 103 and an exhaust passage 132 that receives exhaust gas from exhaust manifold 130. In other embodiments, a turbine 172 in exhaust passage 132 is provided that is operable via the exhaust gases to drive a compressor 174 in intake passage 104. Exhaust passage 132 includes an aftertreatment system 138 in exhaust passage 132 that is configured to treat emissions in the exhaust gas. In one embodiment, aftertreatment system 138 includes a catalyst, such as a selective catalytic reduction catalyst or a three-way catalyst. Other embodiments contemplate an exhaust throttle (not shown) in the exhaust passage 132.

[0030] System 100 further includes a fuel system 150 that is operable to provide fuel from a fuel storage source 152, such as a fuel tank, to cylinders 103. The fuel storage source 152 includes, for example, an onboard fuel pump 154 which delivers fuel from the source 152 via a conduit 156 through a filter (not shown) to a common supply rail 158. The common rail 158 feeds fuel via respective fuel lines 160 to a plurality of fuel injectors 162, at least one per cylinder, and in this example, four injectors 162. The common rail 158 can also be connected via conduit 156 to a pressure regulator valve 164 which in turn is connected to conduit 166 to vent fuel vapor to the intake passage 104 when the pressure in the rail 158 exceeds a predetermined maximum pressure. The fuel pump 154 is operated through a relay or other suitable connection to controller 140.

[0031] A direct injector, as utilized herein, includes any fuel injection device that injects fuel directly into the cylinder volume, and is capable of delivering fuel into the cylinder volume when the intake valve(s) and exhaust valve(s) are closed. The direct injector 162 may be structured to inject fuel at the top of the cylinder. In certain embodiments, the direct injector 162 may be structured to inject fuel into a combustion pre-chamber. Each cylinder 103 may include one or more direct injectors 162. The direct injectors 162 may be the primary or the only fueling device for the cylinders 103, or alternatively the direct injectors may be an auxiliary or secondary fueling device for the cylinders 103. In certain embodiments, the direct injectors 162 are capable of providing the entire designed fueling amount for the cylinders 103 at any operating condition. Alternatively, the direct injectors 162 may be only partially capable, for example the direct injectors 162 may be capable of providing a designated amount of fuel for a specific purpose.

[0032] In still other embodiments, cylinders 103 include a port injector (not shown) in addition to or alternatively to direct injectors 162. In these embodiments, the intake manifold 105 may be divided, or the port fuel injectors may be positioned such that no other cylinder 103 in the system 100 is downstream of the port fuel injector, i.e. only the target cylinder is downstream of the respective port fuel injector.

[0033] The fuel supply to the combustion chamber of each cylinder is controlled by a fuel control module 142 that is a separate controller or a part of controller 140. Fuel control module 142 operates the injectors 162 according to a fuel command produced by controller 140 in response to engine operating conditions. The controller 140 is connected to the fuel pump 154 and to a plurality of other engine condition sensors shown schematically as sensor 170. The engine condition sensors 170 may include, but are not limited to, sensors which monitor engine position, engine speed, manifold static pressure, mass air flow into the manifold, engine temperature, air temperature, cam shaft position (inlet and exhaust), inlet manifold tuning valves, barometric pressure, EGR amount, VGT position, torque demand, gear position, etc.

[0034] In certain embodiments, the system 100 includes a controller 140 structured to perform certain operations to control operations of engine 102. In certain embodiments, the controller 140 forms a portion of a processing subsystem including one or more computing devices having memory, processing, and communication hardware. The controller 140 may be a single device or a distributed device, and the functions of the controller 140 may be performed by hardware or software. The controller 140 may be included within, partially included within, or completely separated from an engine controller (not shown). The controller 140 is in communication with any sensor or actuator throughout the system 100, including through direct communication, communication over a datalink, and/or through communication with other controllers or portions of the processing subsystem that provide sensor and/or actuator information to the controller 140. [0035] In certain embodiments, the controller 140 is described as functionally executing certain operations. The descriptions herein including the controller operations emphasizes the structural independence 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. Aspects of the controller may be implemented in hardware and/or by a computer executing instructions stored in non-transient memory on one or more computer readable media, and the controller may be distributed across various hardware or computer based components.

[0036] Example and non-limiting controller implementation elements include sensors providing any value determined herein, sensors providing any value that is a precursor to a value determined herein, datalink and/or network hardware including communication chips, oscillating crystals, communication links, cables, twisted pair wiring, coaxial wiring, shielded wiring, transmitters, receivers, and/or transceivers, logic circuits, hard-wired logic circuits,

reconfigurable logic circuits in a particular non-transient state configured according to the module specification, any actuator including at least an electrical, hydraulic, or pneumatic actuator, a solenoid, an op-amp, analog control elements (springs, filters, integrators, adders, dividers, gain elements), and/or digital control elements.

[0037] The listing herein of specific implementation elements is not limiting, and any implementation element for any controller described herein that would be understood by one of skill in the art is contemplated herein. The controllers herein, once the operations are described, are capable of numerous hardware and/or computer based implementations, many of the specific implementations of which involve mechanical steps for one of skill in the art having the benefit of the disclosures herein and the understanding of the operations of the controllers provided by the present disclosure.

[0038] 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 parameter can be calculated, and/or by referencing a default value that is interpreted to be the parameter value.

[0039] Certain systems are described following, and include examples of controller operations in various contexts of the present disclosure. In certain embodiments, the controller 140 interprets a cylinder deactivation condition in response to one or more engine operating conditions, and in response to the cylinder deactivation condition the controller 140 provides a cylinder

deactivation command that cuts fuelling to one or more of deactivation cylinders 103b and switches operation of their respective intake valves 206 to a second cam lobe 226' having a second non-zero lift profile and operation of their respective exhaust valves 208 to a fourth cam lobe 228' have a zero lift profile. The determination that a cylinder deactivation condition is present includes determining or interpreting one or more engine operating conditions understood in the art indicating that cylinder deactivation produces favorable operating conditions, such as at low engine load conditions where the remaining non-deactivated cylinders 103 a can satisfy the engine load requirements and fuel efficiency can be achieved by cutting fuelling to one or more of the deactivation cylinders 103b.

[0040] The fuel injectors 162 may inject the fuel supply directly into each respective cylinder 103 or may supply fuel to the inlet valve ports, the injection timing being controlled the controller 140. During cylinder deactivation the supply of fuel to the deactivation cylinders 103b is cut off by individually disabling the respective fuel injectors 162 with the disablement being controlled by the controller 140 with a fuelling command which disables the fuel injection to one or more of the deactivation cylinders 103b while the nominal cylinders 103b fire normally, or are compensated with additional fuel and air flow to meet power demands.

[0041] The operation of the engine 102 is controlled by the controller 140 in response to vehicle operating conditions sensed by the sensors represented by sensor(s) 170. Controller 140 is connected to the fuel injectors 162, either indirectly as shown through fuel control module 142, or directly, to control the injector operation. The controller 140 can determine the injection timing and the injection period or pulse width. Under normal or nominal engine operating conditions, fuel is provided to all cylinders 103. Under a cylinder deactivation condition, fuel in only provided to cylinders 103a and cut off from deactivation cylinders 103b.

[0042] Referring to Fig. 4, there is shown a flow diagram of a procedure 400 for deactivating one or more of the cylinders 103 of engine 102. Procedure 400 begins at operation 402 in which engine 102 is operated under nominal conditions by fuelling all cylinders 103 and operating all cylinder intake valves with a first common non-zero valve lift profile 300 and all exhaust valves with a common third non-zero valve lift profile that can be the same or different as the first nonzero lift profile 300. Procedure 400 further includes an operation 404 to determine a cylinder deactivation condition in response to one or more engine operating conditions. Operation 404 determines if conditions for deactivation of one or more the cylinders 103 are present.

[0043] In response to one or more cylinder deactivation conditions being present, procedure 400 continues at operation 406 to continue to operate a first set of cylinders 103 a with the first nonzero valve lift profile, such as the non-zero lift profile 300 in Fig. 3 or other suitable non-zero lift profile. Procedure 400 also includes an operation 408 to operate a second portion or set of deactivation cylinders 103b with a second non-zero valve lift profile, such as second non-zero lift profile 302 of Fig. 3. The second non-zero lift profile 302 effectively deactivates cylinders 103b while providing a short duration and low lift for the intake valve(s) near BDC of the respective deactivated cylinder during its intake stroke to provide pressure equalization between the cylinder combustion chamber and intake manifold. Cylinder deactivation can continue indefinitely without temporary suspension of the cylinder deactivation to balance pressures while cylinder deactivation conditions are present, thus improving fuel economy and eliminating noise and vibration associated with switching between deactivation and activation operating modes while cylinder deactivation conditions are present.

[0044] Various aspects of the present disclosure are contemplated. According to one aspect, a system includes an internal combustion engine including a plurality of cylinders connected to an intake system and to an exhaust system, and each of the cylinders includes at least one intake valve and at least one exhaust valve. The system also includes a valve actuation mechanism connected to each of the plurality of cylinders. The valve actuation mechanism includes a lifting mechanism with at least two non-zero valve lift profiles. A first non-zero valve lift profile is configured to lift and close the at least one intake valve of each of the plurality of cylinders during a nominal cycle of cylinder operation while the at least one exhaust valve of each of the plurality of cylinders is also lifted and closed with the lifting mechanism during the nominal cycle of cylinder operation. In response to a cylinder deactivation condition, a second non-zero valve lift profile is switchable with the first non-zero valve lift profile to operate the at least one intake valve of each cylinder of a deactivated portion of the plurality of cylinders with the second non-zero valve lift profile to lift each of the at least one intake valves with a short duration, low lift profile while the at least one exhaust valve of each cylinder of the deactivated portion of the plurality of cylinders remains closed during the cylinder deactivation condition.

[0045] In one embodiment, a remaining portion of the plurality of cylinders are operated with the first non-zero valve lift profile while the deactivated portion of the plurality of cylinders are operated with the second non-zero lift profile. In another embodiment, the short duration is between 20 and 80 crank angle degrees. In a refinement of this embodiment, the low lift profile is between 0.25 and 2 millimeters of lift of the at least one intake valve. In another embodiment, the low lift profile is between 0.25 and 2 millimeters of lift of the at least one intake valve.

[0046] In another embodiment, the plurality of cylinders is four cylinders and the portion of the plurality of cylinders is two cylinders. In yet another embodiment, the plurality of cylinders is six cylinders and the portion of the plurality of cylinders is three cylinders.

[0047] In still another embodiment, the system includes a controller structured to interpret the cylinder deactivation condition in response to one or more operating conditions of the internal combustion engine. In response to the cylinder deactivation condition, the controller is configured to switch the valve actuation mechanism to the second non-zero valve lift profile for operation of the at least one intake valve of each cylinder of the deactivated portion of the plurality of cylinders and switch the valve actuation mechanism to a base circle profile for operation of the at least one exhaust valve of each cylinder of the deactivated portion of the plurality of cylinders.

[0048] In yet another embodiment, the first non-zero lift profile obtains a peak lift at a different crank angle than a peak lift of the second non-zero lift profile. In a refinement of this embodiment, or in a separate embodiment, the short duration and low lift of the second non-zero lift profile encompasses or occurs during bottom dead center of an intake stroke of the respective cylinder.

[0049] In another embodiment, a method is disclosed that includes operating an internal combustion engine including a plurality of cylinders, where the plurality of cylinders are each operated with a first non-zero valve lift profile in which at least one intake valve and at least one exhaust valve of each of the plurality of cylinders is lifted and closed during each cycle of operation of the respective cylinder; determining a cylinder deactivation condition in response to one or more engine operating conditions; and in response to the cylinder deactivation condition, operating a deactivated portion of the plurality of cylinders with a second non-zero valve lift profile in which the at least one intake valve of each cylinder of the deactivated portion of the plurality of cylinders is opened with a low lift for a short duration during each cycle of operation of the respective cylinder while the at least one exhaust valve of each cylinder of the deactivated portion of the plurality of cylinders is operated with a zero lift profile so the at least one exhaust valve remains closed during the cylinder deactivation condition.

[0050] In one embodiment, the low lift is between 0.25 and 2 millimeters of lift of the at least one intake valve and the short duration is between 20 and 80 crank angle degrees. In another embodiment, the first non-zero lift profile obtains a peak lift at a different crank angle than a peak lift of the second non-zero lift profile. In a refinement of this embodiment, or in a separate embodiment, the low lift and the short duration of the second non-zero lift profile occurs at bottom dead center of an intake stroke of the respective cylinder.

[0051] According to another aspect, an apparatus is provided that includes a valve actuation mechanism operably connectable to one or more intake valves and one or more exhaust valves of corresponding ones of a plurality of cylinders of an engine. The valve actuation mechanism including a first cam shaft associated with the one or more intake valves of the plurality of cylinders and a second cam shaft associated with the one or more exhaust valves of the plurality of cylinders. The first cam shaft includes a first cam lobe defining a first non-zero valve lift profile and a second cam lobe that defines a second non-zero valve lift profile, and the second cam shaft includes a third cam lobe that defines a third non-zero valve lift profile and a fourth cam lobe that defines a zero valve lift profile. In response to nominal fuelling operation of the plurality of cylinders, the one or more intake valves of each of the plurality of cylinders are opened and closed by the first non-zero valve lift profile and the one or more exhaust valves of each of the plurality of cylinders are opened and closed by the third non-zero valve lift profile during each cycle of operation of the corresponding cylinder. In response to a deactivation condition terminating fuelling to a deactivated portion of the plurality of cylinders, the second non-zero valve lift profile is switchable with the first non-zero valve lift profile for only the deactivated portion of the plurality of cylinders to lift the one or more intake valves of the deactivated portion of the plurality of cylinders for a short duration, low lift profile and the zero valve lift profile is switchable with the third non-zero valve lift profile to prevent lifting of the one or more exhaust valves of the deactivated portion of the plurality of cylinders during the deactivation condition.

[0052] In one embodiment, the low lift profile is between 0.25 and 2 millimeters of lift of the at least one intake valve and the short duration is between 20 and 80 crank angle degrees. In another embodiment, the first non-zero lift profile obtains a peak lift at a different crank angle than a peak lift of the second non-zero lift profile. In a refinement of this embodiment, or in a separate embodiment, the low lift and the short duration of the second non-zero lift profile encompasses bottom dead center of an intake stroke of a respective one of the deactivated portion of the plurality of cylinders.

[0053] 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.

[0054] 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.