SYSTEMS AND METHODS FOR LASH ADJUSTMENT AND CYLINDER DEACTIVATION FOR INTERNAL COMBUSTION ENGINES

RELATED APPLICATIONS

The present application claims the benefit of and priority to UK Patent Application No. GB2204663.5 filed Mar. 31, 2022, the disclosure of which is hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to internal combustion engine systems, and more particularly, but not exclusively, relates to internal combustion engines with valve actuation mechanisms that are capable of cylinder deactivation and/or lash adjustment for selective valve lift.

BACKGROUND

Cylinder deactivation at low engine loads can be accomplished by leaving the intake and exhaust valves of part of the engine cylinders closed during certain operating conditions to save fuel and operate with increased efficiency. Certain cylinder deactivation systems require switching the cam lobe that operates on the deactivated cylinders from a cam lobe with a nominal lift profile to a cam lobe with a zero lift profile. Other cam lobe profiles can be employed for other valve lift conditions, such as for compression release braking. Other systems employ tappets with components that are mechanically locked together for valve lift operating modes and mechanically unlocked from one another to employ lost motion for cylinder deactivation operating modes.

Some internal combustion engines have not effectively employed hydraulic control of lash adjustment for selective valve lift and cylinder deactivation operations. Thus, there is a continuing demand for further contributions in this area of technology.

SUMMARY

Certain embodiments of the present application include unique systems and methods that hydraulically achieve cylinder deactivation for one or more cylinders of an internal combustion engine. The systems and methods may also hydraulically achieve selective lift for one or more of the intake and/or exhaust valves in order to provide, for example, compression release braking or swirl in the corresponding cylinder. Other embodiments include unique apparatus, devices, systems, and methods relating to an internal combustion engine system with a hydraulic circuit that is configured so that one or more cylinders can operate under nominal exhaust valve and intake valve lifts, cylinder deactivation, and/or selective intake and/or exhaust valve lifts that vary in lift height and/or lift timing from the nominal lift thereof.

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

FIG. 1 is a schematic view of one embodiment of an internal combustion engine system with a valve actuation mechanism that provides alternate valve lift and cylinder deactivation capabilities for at least one cylinder.

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

FIG. 3 is a schematic view of a hydraulic circuit for control of the valve actuation mechanism for valve lift operations with hydraulic fluid being provided to a control passage of the hydraulic circuit that controls a reciprocating member associated with an intake valve and/or exhaust valve.

FIG. 4 is the schematic view of FIG. 3 showing the hydraulic fluid being pressurized in the control passage.

FIG. 5 is the schematic view of FIG. 4 showing the reciprocating member hydraulically locked by the control passage.

FIG. 6 is the schematic view of FIG. 5 showing a signal passage being pressurized with a control fluid for cylinder deactivation operations.

FIG. 7 is the schematic view of FIG. 6 showing a control valve opened by the control fluid to relieve hydraulic fluid from the pressurized control passage.

FIG. 8 is the schematic view of FIG. 7 showing the reciprocating member being displaced into the control passage by the three of the intake valve or exhaust valve.

FIG. 9 is the schematic view of FIG. 8 showing the cancellation of pressurization of the signal passage.

FIG. 10 is the schematic view of FIG. 9 showing control passage re-pressurized with hydraulic fluid to lock the reciprocating member extended from the control passage.

FIGS. 11-13 show one example rocker assembly for implementing the hydraulic circuit of the present disclosure.

FIGS. 14-15 show another example rocker assembly for implementing the hydraulic circuit of the present disclosure.

FIG. 16 shows another embodiment valve train with a hydraulic circuit according to the present disclosure for control of the valve actuation mechanism.

FIG. 17 shows another embodiment valve train with a hydraulic circuit according to the present disclosure for control of the valve actuation mechanism.

FIG. 18 is a flow diagram of an embodiment of a method for operating a valve actuation mechanism of an internal combustion engine.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

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.

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 can include 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.

As discussed further below and with further reference to FIG. 2, internal combustion engine system 10 includes a valve actuation system 90. Valve actuation system 90 includes at least one rocker assembly 92, 94 that links at least one intake valve 22 or at least one exhaust valve 24 to a corresponding one of the camshaft lobes 91, 93. Rocker assemblies 92, 94 are configured to move in response to the camshaft lobes 91, 93 acting directly or indirectly on the rocker assemblies 92, 94.

Valve actuation system 90 is configured for valve actuation for the engine 12. Valve actuation system 90 includes at least one rocker assembly 92, 94 linking at least one valve 22, 24 for opening and closing an associated cylinder 14 of the internal combustion engine 12 to one or more camshaft lobes 91, 93. A reciprocating member 97, 99 is connected with the rocker assembly 92, 94. The reciprocating member 97, 99 includes an extended configuration transferring motion from the one or more camshaft lobes 91, 93 to the at least one valve 22, 24. The reciprocating member 97, 99 includes a movable configuration in which the reciprocating member 97, 99 reciprocates relative to the rocker assembly 92, 94. A hydraulic circuit 96, 98 is associated with the rocker assembly 92, 94. The hydraulic circuit 96, 98 is closed in the extended configuration of the reciprocating member 97, 99, and the hydraulic circuit 96, 98 is opened to allow reciprocation of the reciprocating member 97, 99 in the movable configuration.

A method for operating valve actuation system 90 of internal combustion engine 12 includes hydraulically securing a reciprocating member 97, 99 connected with a rocker assembly 92, 94 in an extended position to transfer motion from one or more camshaft lobes 91, 93 to at least one intake valve 22 or exhaust valve 24 via the rocker assembly 92, 94. The intake valve 22 or exhaust valve 24 is movable to open and close an associated cylinder 14 of the internal combustion engine 12. The method further includes allowing the reciprocating member 97, 99 to reciprocate from the extended position so that motion from the one or more camshaft lobes 91, 93 is lost to the intake valve 22 or exhaust valve 24. The reciprocating member 97, 99 is allowed to reciprocate by relieving the hydraulic fluid that hydraulically secures the reciprocating member 97, 99 in response to reciprocation of the reciprocating member 97, 99.

In an embodiment of valve actuation system 90, the rocker assembly 92 is associated with a hydraulic circuit 96, and the rocker assembly 94 is associated with a hydraulic circuit 98. A reciprocating member 97 operates the intake valve 22 in conjunction with the hydraulic circuit 96, and a reciprocating member 99 operates the exhaust valve 24 in conjunction with hydraulic circuit 98.

Reciprocating members 97, 99 have an extended configuration in which the reciprocating members 97, 99 are unable to reciprocate due to hydraulic pressure in the respective hydraulic circuit 96, 98. In the extended configuration, motion from the camshaft lobes 91, 93 is transferred to the intake valve(s) 22 and exhaust valve(s) 24 by the corresponding reciprocating member 97, 99 connected to the rocker assemblies 92, 94. Reciprocating members 97, 99 can be locked or secured in a fully extended position, or a partially extended position to achieve partial valve lift.

Reciprocating members 97, 99 have a movable configuration that is achieved by opening the hydraulic circuit 96, 98 to provide an outlet to vent hydraulic pressure from the respective hydraulic circuit 96, 98, unlocking or decoupling the reciprocating members from the extended configuration. In the movable configuration, motion from the camshaft lobes 91, 93 is not transferred to the intake valve(s) 22 and exhaust valve(s) 24 since the corresponding reciprocating member 97, 99 is allowed to reciprocate in response to the resistance provided by the corresponding intake valve(s) 22 and exhaust valve(s) 24. As a result, motion of the corresponding rocker assembly 92, 94 is not transferred to the intake valve(s) 22 and exhaust valve(s) 24.

Hydraulic circuits 96, 98 are configured to be operated to control a valve lift and/or valve opening and closing timing of the respective intake valves 22 and exhaust valves 24 connected thereto. For example, the valve lift and valve opening/closing timing that can be achieved with rocker assemblies 92, 94 by operation of the hydraulic circuits 96, 98 may include nominal intake/exhaust valve opening/closing timing, cylinder deactivation, and/or selective valve lift operations. Functional modes of operation that can be achieved by the hydraulic circuits(s) 96, 98 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, and/or dynamic skip fire.

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 a 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.

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. A stroke begins either at a top dead center (TDC) when the piston 16 is at the top of cylinder head 20 of the cylinder 14, or at a bottom dead center (BDC), when the piston 16 has reached its lowest point in the cylinder 14.

During the intake stroke, 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.

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.

During the compression stroke in a nominal or standard mode of operation, the intake valves 22 and the exhaust valves 24 are closed. The piston 16 returns toward TDC and fuel is injected near TDC in the compressed air 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.

During the exhaust stroke, the piston 16 is returned toward TDC while the exhaust valves 24 are open. 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 a cylinder deactivation condition or alternative valve lift condition is desired, as discussed further below.

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 40a 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 40a, 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.

The intake passage 36 can be further provided with an optional cooler 44 that is provided downstream of the compressor 40a. In one example, the cooler 44 can be a charge air cooler (CAC). In this example, the compressor 40a 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.

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 40b 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 40b to rotate. The wastegate 50 is a device that enables part of the exhaust gas to by-pass the turbine 40b 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.

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 40b 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 40b and upstream of compressor 40a. 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.

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.

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 (I/O) interface. The memory can include a non-transitory computer-readable medium with instructions stored thereon for execution by the processor to perform the methods disclosed herein.

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.

Controller 80 can be configured to determine one or more engine operating conditions in response to inputs from the various sensors and control the valve actuation mechanism 90 in response thereto. For example, in response to a cylinder deactivation condition, the controller 80 can provide one or more commands to vent the hydraulic circuit 96 and/or the hydraulic circuit 98 to allow corresponding reciprocating member 97, 99 to reciprocate without transferring motion to the connected intake valves 22 or exhaust valves 24. In another example, in response to a selective or alternative valve lift condition, the controller 80 can provide one or more commands to vent the hydraulic circuit 96 and/or hydraulic circuit 98 and then lock or secure one of the reciprocating members 97, 99 at a partially collapsed or reciprocated position so that less than a full valve lift is obtained.

Referring to FIGS. 3-10, an embodiment for hydraulic circuit 96, 98 is shown and designated as hydraulic circuit 100. Hydraulic circuit 100 includes a hydraulic fluid 102 contained therein that is selectively pressurized and vented to provide the desired lift characteristic for the intake and/or exhaust valves 22, 24. The hydraulic fluid 102 is typically the engine oil that is circulated through the engine lubrication system, but other fluid sources are also contemplated and not precluded.

Hydraulic circuit 100 includes a first valve 108 for admitting hydraulic fluid 102 to pressurize the hydraulic circuit 100 for locking or securing the reciprocating member 96, 98 in an extended configuration. Hydraulic circuit 100 also includes a second valve 130 to vent the hydraulic fluid 102 to allow the reciprocating members 96, 98 to reciprocate.

Referring to FIG. 3, hydraulic fluid 102 is provided into hydraulic circuit 100 from a feed 104. Feed 104 is connected to a control passage 106 with first valve 108. First valve 108 may be, for example, a one-way valve or a check valve so that pressurized fluid flow is allowed from feed 104 but reverse flow through feed 104 is prevented. The first valve 108 includes a biased valve member 110 that normally blocks feed 104 from control passage 106. When it is desired to change the valve operation mode, pressurized hydraulic fluid is supplied as indicated by arrow P to lift the valve member 110 from seat 111 and pressurize hydraulic fluid 102 in control passage 106, as shown in FIG. 4.

Control passage 106 extends from a reciprocating member 120 to a second valve 130. Feed 104 is located between the reciprocating member 120 and control valve 130. Second valve 130 is biased to normally close an outlet 132 into which hydraulic fluid pressure is vented to allow reciprocating member 120 to reciprocate in response to resistance provided by the connected intake valve 22 or exhaust valve 24.

Reciprocating member 120 is fluidly connected to control passage 106. Reciprocating member 120 is representative of just one embodiment of reciprocating members 96, 98 discussed above. Reciprocating member 120 can be, for example, a piston, tappet, cylinder, sleeve, rod, or other device connected directly to intake valve(s) 22 or exhaust valve(s) 24. Reciprocating member 120 can also be indirectly connected to intake valve(s) 22 or exhaust valve(s) 24 via an elephant foot, push rod, follower, rocker lever, or other device or devices. Reciprocating member 120 is housed in a chamber 122 of, for example, a rocker lever, pedestal, or other structure of the rocker assembly or cylinder head. Reciprocating member 120 can be normally biased to an extended position as shown in FIGS. 3-5.

Pressurized hydraulic fluid in control passage 106 and chamber 122 hydraulically locks or secures reciprocating member 120 in the extended position of FIGS. 4-5. Reciprocating member 120 is forced in a direction toward chamber 122 by resistance from the connected intake valve(s) 22 or exhaust valve(s) 24, as indicated by arrow F. When second valve 130 is closed, this force pressurizes the hydraulic fluid 102 to close the first valve 108 as indicated by arrow S so that valve member 110 is seated against seat 111, and the reciprocating member 120 is hydraulically locked or secured and cannot move or reciprocate into chamber 122. Therefore, motion from the rocker assembly induced by the camshaft lobes is transferred to open and close the intake valve(s) 22 or exhaust valve(s) 24.

When an alternative operation mode is desired, such as cylinder deactivation or alternate valve lift, the hydraulic fluid 102 in control passage 106 is vented to allow reciprocating member 120 to move into and out of chamber 122. In an embodiment, the second valve 130 is opened to vent hydraulic fluid pressure from control passage 106. For example, in FIG. 6 a signal passage 134 that is in fluid communication with second valve 130 is pressurized with a control fluid, as indicated by arrow C, to displace the second valve 130 in valve passage 136, as indicated by arrow D and shown in FIG. 7. The displaced second valve 130 opens the outlet 132 to allow venting of the pressurized hydraulic fluid 102 in response to resistance forces from valve(s) 22, 24, which in turn allows reciprocating member 120 to move into and out of chamber 122, as indicated by arrow R and shown in FIG. 8.

The open second valve 130 allows hydraulic fluid to enter outlet 132, as indicated by arrows V in FIG. 7. Outlet 132 may be in fluid communication with an accumulator 138. Accumulator 138 may be vented to the crankcase or other component of the engine. Accumulator 138 may include a plunger 140 biased toward control passage 106 to provide leak down of the hydraulic fluid in accumulator 138 as indicated by arrows H in FIG. 8. This prevents hydraulic locking during the next cylinder deactivation event.

When the cylinder deactivation or alternative valve lift mode of operation is no longer desired, the pressurized control fluid in signal passage 134 is cancelled, as indicated by the X shown in FIG. 9. This allows second valve 130 to return to its normally closed position and close outlet 132, as indicated by arrow D′. Pressurized hydraulic fluid 102 is supplied from feed 104 as indicated by arrow P is FIG. 10 to lift valve member 110 from seat 111, as indicated by arrow S′. This re-pressurizes the control passage 106, displacing reciprocating member 120 out of the chamber 122 and locking or securing reciprocating member 120 in the extended position, as shown by arrow E. The first valve 108 then re-seats in response to the resistance force from valve(s) 22, 24, as discussed above.

In the illustrated embodiment, the second valve 130 includes an end member 142 and a blocking portion 144, as shown in FIG. 3. Stem 146 connects end member 142 with blocking portion 144. Blocking portion 144 extends in valve passage 136 and is configured occupy control passage 106 and substantially block or close outlet 132 while second valve 130 is closed, as shown in FIGS. 4-6, 7, and 9-10.

As indicated above, second valve 130 is normally biased by a spring 150 or other device to the closed position against a seat 148. The pressurization of the control fluid in signal passage 134 against end member 142 displaces second valve 130 in valve passage 136 against spring 150 so that stem 146 is at least partially located in control passage 106 to open the outlet 132 for venting of hydraulic fluid 102 from control passage 106, as shown in FIGS. 7-8. Other embodiments contemplate other configurations for second valve 130 capable of selectively closing and opening control passage 106 for venting of hydraulic fluid 102.

The hydraulic circuit 100 does not require a mechanical switch or latch to engage and release reciprocating member 120 to alternate between cylinder deactivation and valve lift modes of operation. Rather, switching between modes of operation is controlled by alternately supplying and cancelling fluid pressure at the first valve 108 and second valve 130 to displace the valve members thereof at the appropriate timing, such as on the base circle of the camshaft lobe, to switch between modes of operation.

The control fluid pressure in signal passage 134 can be activated and cancelled using a solenoid valve (not shown). Signal passage 134 can be connected to a common passage in which a single solenoid valve controls the fluid pressure to multiple signal passages for multiple hydraulic circuits 100. Alternatively each hydraulic circuit 100 of the valve train may include a dedicated solenoid valve for isolated control of the intake and/or exhaust valves of the respective cylinder.

Referring to FIGS. 11-13, an embodiment of the rocker assembly 92, 94 including hydraulic circuit 100 is shown and designated as rocker assembly 200. Rocker assembly 200 includes a rocker lever 202 with a passage 204 for receiving a rocker shaft (not shown) about which the rocker lever 202 rotates. The rocker lever 202 and rocker shaft house the hydraulic fluid circuit 100. In particular, rocker lever 202 includes first valve 108, second valve 130, a cylinder 206 with chamber 122 for receiving reciprocating member 120, and accumulator 138. The control passage 106 extends through rocker lever 202 and the rocker shaft to fluidly connect these components, as discussed above. The rocker lever 202 of FIGS. 11-13 can be, for example, any type of rocker lever employed in a center-pivot type rocker assembly.

Referring to FIGS. 14-15, another embodiment of the rocker assembly 92, 94 including hydraulic circuit 100 is shown and designated as rocker assembly 300. Each rocker assembly 300 includes a rocker lever 302 and a pedestal 310. Rocker levers 302 are connected at one end to the intake valves 22 or the exhaust valves 24. The rocker levers 302 are moved by the respective camshaft lobes 91, 93 about an end pivot 304 connected to the reciprocating member 120.

Reciprocating member 120 is housed in a chamber 122 of a pedestal 310 that includes hydraulic fluid circuit 100. In particular, pedestal 310 includes first valve 108, second valve 130, chamber 122 for receiving reciprocating member 120, and accumulator 138. The control passage 106 extends through pedestal 310 to fluidly connect these components, as discussed above. The rocker assembly 300 of FIGS. 14-15 can be, for example, any type of rocker assembly employing an end-pivot type rocker lever.

Referring to FIG. 16, another embodiment for hydraulic circuit 96, 98 is shown and designated as hydraulic circuit 100′. Hydraulic circuit 100′ is similar to hydraulic circuit 100 discussed above, and can include the same or similar feature discussed above for hydraulic circuit 100. Therefore, like components and functionality between hydraulic circuits 100, 100′ are not specifically discussed with respect to FIG. 16 for the sake of brevity.

Hydraulic circuit 100′ includes a tappet assembly 170 in fluid communication with the control passage 106. Tappet assembly 170 is configured to directly interact with an overhead camshaft 172, such as may be provided in a Type I valve train arrangement. Hydraulic circuit 100′ includes hydraulic fluid 102 contained therein that is selectively pressurized to lock tappet assembly 170 and vented to release tappet assembly 170 to provide the desired lift characteristic for the intake and/or exhaust valves 22, 24.

Tappet assembly 170 includes a housing 180 that houses a lost motion piston 182 and a reciprocating member 184. Reciprocating member 184 is located in a chamber 192 of piston 182. The reciprocating member 184 is biased to an extended position from piston 182 via a spring 186 that is located in chamber 192 of piston 182. Spring 186 contacts an end of reciprocating member 184 and piston 182. Reciprocating member 184 can be locked in the extended position with hydraulic fluid 102 in chamber 192. The slotted opening 188 provides a path for the hydraulic fluid 102 to flow into chamber 192 from control passage 106 and to flow out of chamber 192 into control passage 106.

With reciprocating member 184 locked in the extended position as shown in FIG. 16, the tappet assembly 170 opens and closes the intake and/or exhaust valves 22, 24 in response to cam lobe 172 of camshaft 179 acting on the end of piston 182 to displace the entire tappet assembly 170 downwardly in housing 180. When reciprocating member 184 is unlocked by relieving the hydraulic fluid 102 from chamber 192, the piston 182 moves along reciprocating member 184 to absorb the valve lift from cam lobe 174 without opening, or modifying the lift of, the intake and/or exhaust valves 22, 24.

Referring to FIG. 17, another embodiment for the hydraulic circuit 96, 98 is shown and designated as hydraulic circuit 100″. Hydraulic circuit 100″ is similar to hydraulic circuits 100, 100′ discussed above, and can include the same or similar features discussed above for hydraulic circuits 100, 100′. Therefore, like components and functionality between hydraulic circuits 100, 100′, 100″ are not specifically discussed with respect to FIG. 16 for the sake of brevity.

Hydraulic circuit 100″ includes a tappet assembly 170 for a Type IV or Type V valve train. In particular, piston 182 is connected to a push tube 196 which actuates the intake and/or exhaust valves 22, 24. The cam lobe 174′ acts on an end of reciprocating member 184. When the hydraulic circuit is locked via hydraulic fluid 102 pressurized in chamber 192, the reciprocating member 184 cannot translate in piston member 182, and the tappet assembly 170 operates to open and close the intake and/or exhaust valves 22, 24 in response to cam lobe 172′ of camshaft 170′ acting on reciprocating member 184. When the hydraulic circuit is unlocked by relieving hydraulic fluid 102 from chamber 192 through the slotted opening 188, the reciprocating member 184 can reciprocate in piston 182 so that motion from the cam lobe 174′ is absorbed and the intake and/or exhaust valves 22, 24 do not open or have an altered lift profile.

A method 400 for operating a valve actuation system 90 of an internal combustion engine 12 is shown in the flow diagram of FIG. 18. Referring to FIGS. 3-10, the method 400 includes an operation 402 to hydraulically secure reciprocating member 120 connected with a rocker assembly 92, 94 in an extended position to transfer motion from one or more camshaft lobes 91, 93 to at least one intake valve 22 or exhaust valve 24 via the rocker assembly 92, 94. The intake valve 22 or exhaust valve 24 is movable to open and close an associated cylinder 14 of the internal combustion engine 12.

The method 400 further includes an operation 404 to allow the reciprocating member 120 to reciprocate from the extended position so that motion from the one or more camshaft lobes 91, 93 is lost to the intake valve 22 or exhaust valve 24. The reciprocating member 120 is allowed to reciprocate by relieving the hydraulic fluid 102 that hydraulically secures the reciprocating member 120 in response to reciprocation of the reciprocating member 120.

In an embodiment, the reciprocating member 120 is hydraulically locked by pressurizing a hydraulic circuit 100 in fluid communication with the reciprocating member 120 through a first valve 110.

In an embodiment, the reciprocating member 120 is hydraulically secure by closing the first valve 110 in response to a three acting to displace the reciprocating member 120.

In an embodiment, the hydraulic fluid includes is relieved by pressurizing a control fluid to displace a control valve 130 that blocks the outlet 132 for the hydraulic fluid 102.

In an embodiment, the first valve 110 is closed in a hydraulic fluid feed 104 before hydraulically securing the reciprocating member 120. In an embodiment, the first valve 110 is biased to a closed position.

In an embodiment, the reciprocating member 120 is allowed to reciprocate by venting the hydraulic fluid 102 into an accumulator 138. The accumulator 138 includes a plunger 140 for leak down of the hydraulic fluid 102 in the accumulator 138.

In an embodiment, the reciprocating member 120 is hydraulically secured by pressurizing the hydraulic fluid 102 through a first valve 110 in a hydraulic circuit 100 in fluid communication with the reciprocating member 120. The first valve 110 is closed in response to a force acting on the reciprocating member 120 by the intake valve 22 or exhaust valve 24.

Various aspects of the present disclosure are contemplated. According to one aspect, a system for valve actuation for an internal combustion engine is provided. The system includes at least one rocker assembly linking at least one valve for opening and closing an associated cylinder of the internal combustion engine to one or more camshaft lobes. The system further includes a reciprocating member connected with the rocker assembly. The reciprocating member includes an extended configuration transferring motion from the one or more camshaft lobes to the at least one valve, and the reciprocating member includes a movable configuration in which the reciprocating member reciprocates relative to the rocker assembly. The system also includes a hydraulic circuit associated with the rocker assembly. The hydraulic circuit is closed in the extended configuration of the reciprocating member, and the hydraulic circuit is opened to allow reciprocation of the reciprocating member in the movable configuration.

In an embodiment, the reciprocating member connects the at least one valve to a rocker lever. In an embodiment, the reciprocating member is connected to one end of a rocker lever and the at least one valve is connected to an opposite end of the rocker lever.

In an embodiment, the hydraulic circuit is located at least partially within the rocker assembly. In an embodiment, the reciprocating member is normally biased toward an extended position and moves reciprocally relative to the rocker assembly in response to resistance from the at least one valve while the reciprocating member is in the movable configuration.

In an embodiment, the hydraulic circuit includes a first valve for admitting hydraulic fluid into the hydraulic circuit to pressurize the hydraulic circuit, and in the extended configuration of the reciprocating member the first valve is forced closed by the hydraulic fluid in response to a force acting on the reciprocating member. In a further embodiment, the hydraulic circuit includes a hydraulically actuated second valve for opening the hydraulic circuit to vent the hydraulic fluid while the first valve is closed. In a further embodiment, the hydraulic circuit includes an outlet downstream of the second valve for receiving the hydraulic fluid vented from the hydraulic circuit. In a further embodiment, the outlet is connected to an accumulator, and the accumulator includes a plunger that is normally biased toward the outlet for leak down of the hydraulic fluid in the accumulator. In a further embodiment, the second valve is normally biased to a closed position, and the second valve is hydraulically actuated from the closed position to an open position to vent the hydraulic circuit.

In an embodiment, the hydraulic circuit includes a hydraulically actuated valve that is positionable to open the hydraulic circuit and vent hydraulic fluid through an outlet in response to a force acting on the reciprocating member in the movable configuration. In a further embodiment, the hydraulically actuated valve includes a blocking portion for normally closing the outlet of the hydraulic circuit, and the blocking portion is movable out of the hydraulic circuit to open the outlet to vent hydraulic fluid.

According to another aspect, a method for operating a valve actuation mechanism of an internal combustion engine is provided. The method includes hydraulically securing a reciprocating member connected with a rocker assembly in an extended position to transfer motion from one or more camshaft lobes to at least one valve via the rocker assembly. The at least one valve is movable to open an close an associated cylinder of the internal combustion engine. The method further includes allowing the reciprocating member to reciprocate from the extended position so that motion from the one or more camshaft lobes is lost to the at least one valve. Allowing the reciprocating member to reciprocate includes relieving the hydraulic fluid that hydraulically secures the reciprocating member in response to reciprocation of the reciprocating member.

In an embodiment of the method, hydraulically securing the reciprocating member includes pressurizing a hydraulic circuit in fluid communication with the reciprocating member through a first valve. In a further embodiment, hydraulically securing the reciprocating member includes closing the first valve in response to a force acting to displace the reciprocating member.

In an embodiment of the method, relieving the hydraulic fluid includes pressurizing a control fluid to displace a control valve that blocks the outlet for the hydraulic fluid.

In an embodiment, the method includes closing a first valve in a hydraulic fluid feed before hydraulically securing the reciprocating member. In an embodiment, the method includes biasing the first valve to a closed position.

In an embodiment of the method, allowing the reciprocating member to reciprocate includes venting the hydraulic fluid into an accumulator, the accumulator including a plunger for leak down of the hydraulic fluid in the accumulator.

In an embodiment of the method, hydraulically securing the reciprocating member includes pressurizing the hydraulic fluid through a first valve in a hydraulic circuit in fluid communication with the reciprocating member, and closing the first valve in response to a force acting on the reciprocating member by the at least one valve.

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.

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.

SYSTEMS AND METHODS FOR LASH ADJUSTMENT AND CYLINDER DEACTIVATION FOR INTERNAL COMBUSTION ENGINES

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