EP3073071A1 - Nockenwellendrehmomentbasierte anpassung der ventilsteuerzeit - Google Patents

Nockenwellendrehmomentbasierte anpassung der ventilsteuerzeit Download PDF

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Publication number
EP3073071A1
EP3073071A1 EP15160902.1A EP15160902A EP3073071A1 EP 3073071 A1 EP3073071 A1 EP 3073071A1 EP 15160902 A EP15160902 A EP 15160902A EP 3073071 A1 EP3073071 A1 EP 3073071A1
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EP
European Patent Office
Prior art keywords
valve
camshaft
cam
rocker
driven
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP15160902.1A
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English (en)
French (fr)
Inventor
Íñigo Guisasola
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Caterpillar Energy Solutions GmbH
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Caterpillar Energy Solutions GmbH
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Publication date
Application filed by Caterpillar Energy Solutions GmbH filed Critical Caterpillar Energy Solutions GmbH
Priority to EP15160902.1A priority Critical patent/EP3073071A1/de
Publication of EP3073071A1 publication Critical patent/EP3073071A1/de
Withdrawn legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
    • F01L13/0015—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque
    • F01L13/0021—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque by modification of rocker arm ratio
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
    • F01L13/0015—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque
    • F01L13/0036—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque the valves being driven by two or more cams with different shape, size or timing or a single cam profiled in axial and radial direction
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
    • F01L13/06—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for braking
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L2800/00—Methods of operation using a variable valve timing mechanism

Definitions

  • the present disclosure generally relates to valve operation systems for an internal combustion engine and, more particularly, to controlling valve closing in variable valve timing configurations.
  • rocker arm configurations are used to operate intake and exhaust valves.
  • several valves are provided, for example, within a cylinder head, each being operated by a respective rocker arm configuration.
  • an intake and an exhaust rocker arm configuration may control the opening and closing of two intake valves and two exhaust valves, respectively.
  • a common camshaft driving the rocker arm configurations may, for example, ensure respective timings.
  • intake and exhaust valves are driven by specifically shaped cams, thereby enforcing a specific valve timing that provides, for example, a Miller timing with a respective valve overlap.
  • valve timing adjustment mechanism known that allow, for example, an operation mode specific adjustment of valve timings.
  • the present disclosure is directed, at least in part, to improving or overcoming one or more aspects of prior systems.
  • a method for deriving a control parameter for a variable valve actuation assembly using a valve spring driven /cam decoupled valve closing process comprises the steps of providing a camshaft driven valve actuation assembly that is configured to provide a cam driven valve opening procedure and the valve spring driven / cam decoupled valve closing process, rotating the camshaft through a sequence of the cam driven valve opening process and the valve spring driven / cam decoupled valve closing process, during the rotation, measuring a torque to be provided for the rotation, and deriving the control parameter from the detected torque.
  • an internal combustion engine comprises a plurality of cylinder units with a plurality of engine valves, a plurality of camshaft driven valve actuation assemblies as summarized above for respectively operating one or more engine valves of the for the plurality of engine valves of the plurality of cylinder units, and a control unit configured to control the cam decoupling units to adapt the closing process of the engine valves for in particular synchronizing the valve closing times of the plurality of engine valves.
  • the present disclosure may be based in part on the realization that in certain VVT (variable valve drive) concepts, valves are decoupled from the cam contour when closing the valve.
  • VVT variable valve drive
  • VVT concepts valves are decoupled from the cam contour when closing the valve.
  • European patent applications entitled “VARIABLE VALVE TIMING BY ROCKER ARM ROTATION AXIS DISPLACEMENT” and "PUSH ROD BASED VARIABLE VALVE TIMING SYSTEMS” filed by the applicant on the same day as the present application, which are incorporated herein by reference.
  • VVT concepts being based on a decoupling from the camshaft system
  • valve spring forces for different valve springs of engine valves operated by such a VVT concept may differ. Accordingly, the distribution of differing valve spring forces may have an influence on the closing of the inlet valves employed within an engine as closing times of those valves differ, e.g. they are not sufficiently synchronized. It was further realized that a measurement of the valve spring forces may be used to take proper action. For example, one may "uncouple" - e.g. by feedback control - the valves at different times from the cam contour so that they are closing essentially at the same time (with respect to the OT of every station) and the respective areas (flows) during the valve activation stays essentially the same.
  • VARIABLE VALVE TIMING BY ROCKER ARM ROTATION AXIS DISPLACEMENT this may be achieved by displacing the position of the second cylinder (and thus the control opening) with respect to the rocket arm pivot movement, to thereby vary the crank angle (time) at which the displacement movement of the rocker arm mount and, thus, the decoupling is initiated.
  • exemplary embodiments are disclosed that illustrate the control concepts, which use the measurement of the torque provided via the camshaft to operate engine valves.
  • the control concepts can be employed, for example, in internal combustion engines such as the one schematically illustrated in of Fig. 1 .
  • the control concepts are configured to provide adjustable valve timings as illustrated in Fig. 2 .
  • Figs. 3 and 4 illustrate the torque as it is present at the camshaft for multi-cylinder engines, e.g. four and eight cylinder engines.
  • exemplary cam decoupled valve closing mechanisms are disclosed in connection with Figs. 5 and 6 .
  • Fig. 1 an exemplary embodiment of an internal combustion engine 10 is illustrated that uses a camshaft driven rocker arm system for valve actuation exemplarily for a pre-combustion chamber ignited gaseous fuel operation.
  • the valve actuation of engine 10 provides for a cam decoupled operation mode in which the rocker arm system is decoupled from the camshaft system such that in particular the closing process of the valve depends essentially on the valve spring configuration.
  • Engine 10 may include features not shown, such as a fuel system, an air system, a cooling system, drivetrain components, etc.
  • engine 10 is exemplarily considered to be a four-stroke gaseous fuel internal combustion engine.
  • engine 10 may be any type of engine (two-stroke, turbine, gas, diesel, natural gas, propane, etc.).
  • engine 10 may be of any size, with any number of cylinders, and in any configuration ("V", in-line, radial, etc.).
  • Engine 10 may be used to power any machine or other device, including locomotive applications, on-highway trucks or vehicles, off-highway trucks or machines, earth moving equipment, generators, aerospace applications, marine applications, pumps, stationary equipment, or other engine powered applications.
  • Engine 10 includes an engine block 12 having a plurality of cylinder units 14 (one of which is illustrated in Fig. 1 ).
  • a piston 16 is slidably disposed within cylinder unit 14 (e.g. within a cylinder liner 15) to reciprocate between a top-dead-center position (TDC) and a bottom-dead-center position (BDC).
  • a connecting rod 18 connects piston 16 to an eccentric crankpin 20 of a crankshaft 22 such that reciprocating motion of piston 16 results in rotation of crankshaft 22.
  • Engine 10 includes further a cylinder head 24 (enlarged in Fig. 1 ) that is mounted to engine block 12 and covers cylinder unit 14, thereby delimiting a main combustion chamber 26.
  • Cylinder head 24 provides intake and exhaust openings 28 to charge main combustion chamber 26, for example, with a charge air-gaseous fuel mixture and to release exhaust gases out of main combustion chamber 26 into an exhaust gas system (not shown).
  • Engine valves 30 are configured to selectively open and close respective openings 28, e.g. by a valve stem with a valve head (see also Fig. 3 ).
  • Each cylinder unit 14 may include multiple intake and exhaust openings 28 and respectively multiple intake and exhaust valves 30.
  • Engine 10 further may include an assembly configured to initiate a combustion event.
  • engine 10 may include a pre-combustion chamber assembly 32 (also referred to as pre-combustion chamber ignition device), which is positioned within cylinder head 24, for example between valves 30.
  • Pre-combustion chamber assembly 32 may be configured in a variety of ways. In general, it is an assembly configured to initiate a combustion event within a pre-combustion chamber, and to direct the combustion into main combustion chamber 26.
  • the internal combustion engine 10 may include a series of valve actuation assemblies 40 (one of which is exemplarily illustrated in Fig. 1 ). Multiple valve actuation assemblies 40 may be provided per cylinder unit 14, e.g. for different valve types (e.g. intake or exhaust valve). For example, valve actuation assembly 40 is used to open and close the intake valve(s) and another, for example similar, valve actuation assembly 40 may be provided to open and close the exhaust valve(s).
  • valve actuation assembly 40 is used to open and close the intake valve(s) and another, for example similar, valve actuation assembly 40 may be provided to open and close the exhaust valve(s).
  • Valve actuation assembly 40 includes a rocker arm 46.
  • Rocker arm 46 is pivotally mounted on cylinder head 24 by a rocker shaft unit 49 via a rocker shaft 50 and interacts with engine valves 30 at a valve actuation section 46A and with a push rod 48 at a push rod section 46B.
  • Push rod section 46B engages with one end of push rod 48, the other end engages (as exemplarily shown in Fig. 1 ) with a cam lobe 58 disposed on camshaft 56 to drive (lift) push rod 48 when camshaft 56 is rotated.
  • Camshaft 56 may be driven by crankshaft 22.
  • Camshaft 56 may be connected with crankshaft 22 in any manner readily apparent to one skilled in the art where rotation of crankshaft 22 may result in a rotation of camshaft 56.
  • camshaft 56 may be connected to crankshaft 22 through a gear train (not shown).
  • the displacement of push rod 48 corresponds to an actuation movement of push rod 48 that may result in a conventional activation of valve 30, which is herein referred to as a blocked operation mode (e.g. a conventional valve operation via push rod/camshaft configurations having a blocked, i.e. spatially fixed position of rocker shaft 50 with respect to cylinder unit 14).
  • the actuation movement includes a lifting movement L and a return movement R.
  • Lifting movement L is caused by the shape of cam lobe 58 and results in a lifting force Fl onto rocker arm 46 redirected via the pivot mounting onto the valve stem.
  • the valve stem of valve 30 moves from a closed position C to an open position O during lifting movement L (see also Figs. 5 and 6 ).
  • valve actuation assembly 40 may include - as a biasing force providing unit - for example, a valve spring 52 that provides a biasing force Fb onto the valve stem of valve 30 towards the closed position and, thus, generally counteracts against lifting force Fl.
  • biasing force Fb enforces closing of the valve as well as return movement R. In consequence, opening 28 is closed via the respective valve head.
  • the blocked operation results in an oscillation of rocker arm 46 about its pivot point in dependence of the shape of cam lobe 58 and in respective opening duration of valve(s) 30.
  • camshaft 56 may include additional cam lobes to engage with additional push rods in order to actuate additional engine valves.
  • Fig. 2 shows a plot of exemplary valve lift curves.
  • Fig. 2 shows an exhaust valve curve 72 extending from about 140° to 370° crankshaft angle during an exhaust stroke, and an intake valve curve 74 extending from about 350° to 490° crankshaft angle during an intake stroke.
  • the schematically indicated valve lift curves 72 and 74 illustrate as an example an extreme Miller valve timing that reaches a high efficiency and may be applied, for example, at full load.
  • the operation at full load is indicated by reference F.
  • those valve lift curves 72 and 74 may not be optimal to start engine 10 or to operate the same at part load as then a relative small load acceleration may be present.
  • a filling optimized lift curve 76 for an intake valve is schematically included in Fig. 2 .
  • Filling optimized lift curve 76 extends, for example, from 350° to 570° crankshaft angle and allows to increase the filling of main combustion chamber with charge air. Filling optimized operation may reduce the risk of knocking at part load such that a larger power output and improved load acceleration may be achieved. In particular when operated as a separate power supply, this aspect may affect the combustion tuning.
  • the cam based operation mode (indicated with reference B in Fig. 2 ) is implemented by a specific shape (broad shape) of cam lobe 58. Accordingly, during start of the engine (part load operation) blocked operation mode is activated.
  • Cam decoupled configurations as explained exemplarily in connection with Figs. 5 and 6 may allow adaptation of valve timings, for example, for the full load operation of engine 10 in Miller-like manner.
  • the decoupling shifts the closing process away from a dependence of the cam shape to a dependence from delay force Fd provided by valve spring 52.
  • the decoupling modifies the torque acting onto camshaft 56.
  • the starting point and end point of the decoupling may result in some kind of discontinuity of the torque development during the rotation of camshaft 56.
  • the decoupling may not be complete such that a remaining force will act onto camshaft 56, thereby smoothing the discontinuity.
  • the torque may further be subject to an averaging process due to the respective mechanical boundary conditions.
  • a torque measurement device 60 is provided to measure a torque acting onto camshaft 56 during the rotation of camshaft 56.
  • Torque measurement device 60 may comprise, for example, one or more strain gauges. Strain gauges may be positioned at the gear train and/or next to one or all of cylinder units 14.
  • a torque distribution as shown in Figs. 3 and 4 may be detected that provides information on the torque needed to turn the camshaft.
  • the torque varies during the stages of the actuation movement of the various valves (lifting movement L and return movement R).
  • the torque depends on various mechanical components such as valve springs 52, joints between the various parts, the temperature of the engine (affecting the lubrication) etc.
  • torque measurement device 60 is provided for measuring the torque development of each valve actuation assembly without and/or without combustion and setting the control parameters, which are available for the respective decoupled operation mode, to ensure desired valve closing processes. Thereby the closing processes of a single cylinder unit as well as the synchronization of the closing processes for multiple cylinder units may be achieved.
  • torque measurement device 60 is provided for continuously measuring the torque development during the operation of the engine. This may allow a continuous control of the closing process of each valve actuation assembly individually as well as with respect to the other valve actuation assemblies.
  • torque measurement device 60 may screwed to engine block 12 once during the installation of engine 10 or it maybe continuously installed. Torque measurement device 60 may turn the gear system of camshaft 56 one round and store a measured torque characteristics as illustrated in Figs. 3 and 4 exemplarily for four and eight cylinder engines during a cam based actuation. In dependency of the cam contour, the kinematics of the valve drive, and the firing order, valve spring force of every valve system may essentially be derived from the torque characteristics.
  • a negative torque may be generated at the closing side of the cam, e.g. the camshaft would continue rotating due to the biasing force, if a negative torque is not supplied.
  • positive and negative sections may be generated due to the differing cam lobe interactions on the opening and closing sides.
  • asymmetries in the torque characteristic mac be caused by engine configurations such as V-engine configurations as well as cam shapes and spring types.
  • the torque based information can be used to initially adapt the valve actuation configuration and/or it can be used as an input parameter for the control of variable valve timing systems. It may further allow taking actions against any initial and/or during operation (due to wear out, clearance changes, or relaxations) growing deviations of the various valve spring forces.
  • torque measurement device 60 may be removed in case of an initial setting or the measurement of the torque characteristics may be integrated in the camshaft system (for example using strain gauges), so the measurement can take place during operation and/or at every start of the engine.
  • the herein disclosed torque based approach may include the whole chain of tolerances in its measurement, which may play a role for the valve actuation such as engine block, camshaft, valve drive etc.
  • the torque characteristics may allow determining in which position the middle of the cam contour is located to even consider the same for the setting of the cam based valve actuation mode.
  • Valve actuation assembly 140 includes inter alia components such as a camshaft 156, a cam lobe 158, and a push rod 148 (camshaft system exemplarily shown in Fig. 1 ).
  • valve actuation assembly 140 includes a rocker system 144 including a rocker arm 146 and a rocker shaft unit 149 comprising a rocker shaft 150 configured to provide an axis 150A of rotation for the pivot movement of rocker arm 146.
  • Rocker shaft unit 149 further comprises a rocker shaft mount 149A for mounting rocker shaft 150.
  • rocker shaft mount 149A is configured to provides the possibility to displace rocker shaft 150 to vary the position of rocker shaft 150 such as the relative position with respect to valve opening 128 and the distance to the cover face of main combustion chamber 126 (the latter illustrated by arrow 149' in Fig. 5 ).
  • Rocker shaft unit 149 may further comprise a guide structure 149B for guiding rocker shaft mount 149A during such a displacement movement.
  • rocker shaft unit 149 may further comprise a force generating unit 149C, which is configured to provide a biasing force Fb' counter-acting a hydraulic force Fh as discussed below in more detail.
  • Biasing force Fb' may in particular be set for enforcing the displacement and allowing a return movement and/or may be provided to supplement biasing force Fb generated by valve spring 152.
  • valve actuation assembly 140 comprises a hydraulic valve timing adjustment system 160.
  • Hydraulic valve timing adjustment system 160 of Fig. 3 is based on a hydraulic system that is configured, for example, to be fluidly connected to an engine oil system (not shown) and/or to be part of a separate hydraulic system.
  • Hydraulic valve timing adjustment system 160 is configured to control the position of rocker shaft mount 149A, and in particular decouple the pivot movement of rocker arm 146 from the camshaft system.
  • hydraulic valve timing adjustment system 160 is configured to position rocker shaft 150 in a spatially fixed position with respect to valve opening 128. A respective blocked state B' is shown in Fig. 5 .
  • hydraulic valve timing adjustment system 160 is configured to bring rocker shaft mount 149A in a flexible state. The flexible state enables a displacement movement of rocker shaft 150.
  • hydraulic valve timing adjustment system 160 comprises a first piston 164A housed in a first cylinder 164B, for example a hollow-cylinder.
  • First piston 164A is mounted to rocker shaft unit 149, for example to rocker shaft mount 149A on top of rocker shaft 50 as shown in Fig. 5 .
  • Hydraulic valve timing adjustment system 160 may further comprise a second piston 166A housed in a second cylinder 166B.
  • Second piston 166A is connected to rocker arm 46 at an eccentric position with respect to axis 150A of rotation.
  • second piston 166A may be connected to valve actuation section 146A (as shown in Fig. 3 ) such as via a mechanical connection 165.
  • it may be connected to push rod section 146B of rocker arm 146.
  • the eccentric connection may provide a cyclical synchronization of hydraulic valve timing adjustment system 160 with camshaft 156.
  • second cylinder 166B comprises at least one control opening 167 to release hydraulic fluid from second cylinder 166B.
  • control opening 167 is position within the sidewalls of second cylinder 166B to be covered (as shown in Fig. 3 ) and uncovered (not shown) by second piston 166A during the pivoting movement of rocker arm 146.
  • second cylinder 166B may itself be mounted in a displaceable manner to allow for adjusting the relative position between control opening 167 and second piston 166A during the pivoting movement of rocker arm 146 and the corresponding movement of piston 166A.
  • a respective displacement unit 167A is indicated in Fig. 5 .
  • hydraulic valve timing adjustment system 160 comprises an exemplary hydraulic connection 168 hydraulically connecting first cylinder 164B and second cylinder 166B (specifically the inner volume thereof), thereby providing a hydraulic interaction between rocker shaft unit 149 and the eccentric position at rocker arm 146.
  • hydraulic valve timing adjustment system 160 may further comprise a supply valve 168A for a fluid connection with a hydraulic fluid source 169 (e.g. the engine oil system).
  • a block valve 168B may be provided to be able to block or even to control the release of hydraulic fluid through control opening 167. This may allow, in particular, adjusting the dynamics of the closing of valve 130.
  • a further block valve 168B' may be provided between first cylinder 164B and second cylinder 166B.
  • supply valve 168A and block valves 168B, 168B' may be connected to a control unit 180 via control lines 182.
  • control unit 180 may be configured to activate the valves to take on/ to support taking on blocked state B or flexible state.
  • displacement unit 167A may be controlled by control unit 180.
  • the geometries of the joints between rocker arm 146 and valve stem 170 as well as rocker arm 146 and push rod 148 may be configured such that, during the respective mechanical movements of rocker arm 146 and push rod 148, the respective joint parts will be brought into or maintained in proper position with respect to each other to properly interact as a joint when needed.
  • any tilt of push rod 148 may vary in dependence of the displacement.
  • one of the joint parts may comprise, for example, a cone-like shape.
  • Alternative configurations may be apparent to the skilled person to maintain proper joint alignment despite temporal introduction of a gap between the joint parts.
  • control unit 180 may use the information gained from the torque measurement to set control parameters such as the displacement of second cylinder 166B by displacement unit 167A and/or the operation of block valves 168A, 168B, 168B' and/or the pressure within the hydraulic system and/or any supporting delay force Fd' by force generating unit 149C. Further control parameters will be apparent to the skilled person in view of specific implementations.
  • Valve actuation assembly 240 includes inter alia a camshaft system 260 with components such as a camshaft 256, a cam lobe 258, and a split push rod 248. Moreover, valve actuation assembly 240 includes a rocker arm 246 mounted to a rocker shaft 250, and a biasing force generating unit.
  • the biasing force generating unit is configured, for example, as a valve spring 252, which provides a biasing force Fb redirected via the pivotably mounted rocker arm counter-acting lifting force Fl, in particular for enforcing return movement R.
  • valve actuation assembly a40 is based on split push rod 248 that interacts with cam lobe 258 to be displaced, during a rotation of camshaft 256, in accordance with a desired actuation movement during cam driven operation mode.
  • Split push rod 248 comprises a rocker part 248A and a cam part 248B connected at tilt connection 249.
  • Tilt connection 249 is configured to allow for an adjustment of tilt angle ⁇ between rocker part 248A and cam part 248B.
  • rocker part 248A interacts with push rod section 246B, in particular for providing lifting force Fl onto rocker arm 246 during lifting movement L.
  • a lower end 248B' of cam part 248B interacts with cam lobe 258, in particular via a roller follower configuration 284 described below.
  • Camshaft system 260 comprises further an intermediate guidance element 262 providing an intermediate guidance face 263 for guiding tilt connection 249.
  • the contour of intermediate guidance face 263 may be plane (for example extending essentially along the direction between push rod section 246B and camshaft 256 or at a desired angle).
  • the contour may alternatively be shaped in a curved manner in same section as described below.
  • cam lobe 258 and the contour of intermediate guidance face 263 may define the movement of rocker arm 246 during cam driven operation.
  • tilt connection moves back and forth along a cam control section 263A of intermediate guidance face 263, wherein tilt angle ⁇ is maintained below 180°.
  • intermediate guidance face 263 comprises a decoupling section 263B being shaped to provide in combination with the shape of cam lobe 258 a desired lifting movement L in the decoupled operation mode.
  • decoupling section is configured and arranged such that tilt angle ⁇ increases up to and beyond 180° such that biasing force Fb forces tilt connection 249 to loose contact with intermediate guidance face 263 and further increase tilt angle ⁇ .
  • tilt connection 249 bends over a straight alinement - indicated as dashed line 251 - of rocker part 248A and cam part 248B.
  • cam control section 263A is configured to be plane, while decoupling section 263B is curved to move tilt connection 249 towards (and in some embodiments slightly beyond) the straight alignment.
  • a positioning unit 264 allows displacement of intermediate guidance element 262.
  • cam control section 263A can also be configured to affect the actuation movement.
  • the contour may be shaped such that a displacement of cam part 248B of push rod 248 will result in a corresponding displacement of push rod section 246B of rocker arm 246, thereby essentially maintaining the actuation movement as defined by cam lobe 258.
  • the actuation movement is defined by cam lobe 258.
  • the shape of the contour will define in combination with a shape of cam lobe 258 the displacement of push rod section 246B during the lifting movement.
  • the actuation movement is at least partly decoupled from the shape of cam lobe 258.
  • the latter may in particular be the case when the contour or at least one of the contour sections is a plane tilted with respect to line 251 or provides a curved surface as it is the case for the illustrated decoupling section 263B, thereby enforcing a change in tilt angle ⁇ .
  • a roller 265 forms tilt connection 249 for providing a roll-off movement between tilt connection 249 and intermediate guidance face 263.
  • lower end 248A' and upper end 248B" are mounted to an axis of roller 265.
  • the position of roller 265 during cam driven operation is shown in solid lines (e.g. rolling along cam control section 263A).
  • roller 265 is shown in dashed lines when being moved to the straight alignment (line 251) of split push rod 248 during decoupled operation mode, i.e. just before being decoupled from the cam interaction.
  • a brake unit 267 is further provided.
  • Break unit 267 is configured to provide a delay force Fd onto tilt connection 249 in particular at tilt angles larger 180°, thereby delaying the lateral movement of tilt connection 249 during return movement R.
  • brake unit 267 may comprise a pressing member 267A pressing onto roller 265 during the return movement.
  • brake unit 267 may comprise a spring 267B and/or a damping device 267C.
  • brake unit 267 may be configured to allow for controlling delay force Fd during return movement R.
  • biasing force Fb has essentially no counterforce such that valve 230 closes, rocker arm 246 pivots back, and push rod section 246B moves down, thereby further increasing tilt angle ⁇ .
  • break unit 267 delays the closing be slowing down the change rate (increase rate) of tilt angle ⁇ .
  • valve 230 is closed while lower end 248B' of cam part 248B is still displaced (lifted) by cam lobe 258.
  • lower end 248B' will follow the decreasing slope of cam lobe 258 and roller 265 will return to interact with intermediate guidance face 263, thereby finalizing return movement R and bringing tilt connection 249 again into tilt angles smaller 180°.
  • camshaft system 260 is brought back into the initial condition during which cam part 248B interacts with camshaft 256 next to cam lobe 258 and valve 230 maintains closed. The next actuation movement will be initiated again by cam lobe 58 at first by the lifting movement and then the cam decoupled return movement.
  • hollow cylinder body 285 may comprise an opening 285A for interacting with cam part 248B.
  • opening 285A of hollow cylinder body 285 may be configured in size and/or shape such that the required angular range for cam part 248B of split push rod 248 can be accepted by roller follower configuration 284 during the interaction of wheel 286 with cam lobe 258.
  • Internal combustion engine 10 of Fig. 1 may in particular comprise a valve actuation assembly as disclosed in connection with Fig. 6 , as well as cylinder head 24 with valve opening 28 fluidly connecting combustion chamber 26 with a charge air system, and engine valve 30.
  • engine valve 230 may comprise valve stem 270 with valve head 270A for closing valve opening 228 (closed position C shown in solid lines, while open position shown in dashed lines in Fig. 6 ), valve stem guidance 271 for guiding a movement of valve stem 270, and valve spring 252.
  • valve spring 252 may be configured such that its spring force acts as biasing force Fb, in particular by acting via the top of valve stem 270 onto rocker arm 246.
  • intermediate guidance element 262 and/or break unit 267 may be connected to a control unit 280 via control lines 282 to control the movement of those elements for start operation mode B or for full load operation F.
  • break unit 267 may be replaced by a further guiding surface for limiting and defining the return movement of the tilt connection.
  • roller 265 may be replace by a sliding part.
  • control unit 180 may use the information gained from the torque measurement to set control parameters such as the displacement of intermediate guidance element 262 by positioning unit 264 and/or the operation of break unit 267. Further control parameters will be apparent to the skilled person in view of specific implementations such as a tilt of intermediate guidance element 262 or the shape of the further guiding surface for limiting and defining the return movement of the tilt connection.
  • cam decoupling units formed by the various components required to decouple the valve stem from the cam such as disclosed in connection with Figs. 5 and 6
  • the torque characteristic and, e.g. the valve spring force present in that selected valve actuation system may be derived. This may be, for example, performed at the engine start stepwise for each valve actuation system.

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  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Valve Device For Special Equipments (AREA)
EP15160902.1A 2015-03-25 2015-03-25 Nockenwellendrehmomentbasierte anpassung der ventilsteuerzeit Withdrawn EP3073071A1 (de)

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EP15160902.1A EP3073071A1 (de) 2015-03-25 2015-03-25 Nockenwellendrehmomentbasierte anpassung der ventilsteuerzeit

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EP15160902.1A EP3073071A1 (de) 2015-03-25 2015-03-25 Nockenwellendrehmomentbasierte anpassung der ventilsteuerzeit

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EP3073071A1 true EP3073071A1 (de) 2016-09-28

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10718238B2 (en) 2017-11-03 2020-07-21 Indian Motorcycle International, LLC Variable valve timing system for an engine
US11594081B2 (en) 2021-06-11 2023-02-28 Honda Motor Co., Ltd. Valve testing for engines

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4483283A (en) * 1983-05-13 1984-11-20 Hausknecht Louis A Variable valve control system with dampener assembly
EP1816456A1 (de) * 2005-08-02 2007-08-08 Castrol Limited Verfahren und Vorrichtung zur Drehmomentmessung an einer Kurbelwelle einer Brennkraftmaschine

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4483283A (en) * 1983-05-13 1984-11-20 Hausknecht Louis A Variable valve control system with dampener assembly
EP1816456A1 (de) * 2005-08-02 2007-08-08 Castrol Limited Verfahren und Vorrichtung zur Drehmomentmessung an einer Kurbelwelle einer Brennkraftmaschine

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10718238B2 (en) 2017-11-03 2020-07-21 Indian Motorcycle International, LLC Variable valve timing system for an engine
US11594081B2 (en) 2021-06-11 2023-02-28 Honda Motor Co., Ltd. Valve testing for engines

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