US20070266973A1 - Valve actuating mechanism - Google Patents

Valve actuating mechanism Download PDF

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Publication number
US20070266973A1
US20070266973A1 US11/744,964 US74496407A US2007266973A1 US 20070266973 A1 US20070266973 A1 US 20070266973A1 US 74496407 A US74496407 A US 74496407A US 2007266973 A1 US2007266973 A1 US 2007266973A1
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United States
Prior art keywords
valve
rocker
combustion engine
internal combustion
latching mechanism
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Abandoned
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US11/744,964
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English (en)
Inventor
Timothy Mark Lancefield
Ian Methley
Mark Andrew Richard Walton
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Mechadyne PLC
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Mechadyne PLC
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Assigned to MECHADYNE PLC reassignment MECHADYNE PLC ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: LANCEFIELD, TIMOTHY MARK, METHLEY, IAN, WALTON, MARK ANDREW RICHARD
Publication of US20070266973A1 publication Critical patent/US20070266973A1/en
Abandoned 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
    • 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
    • F01L13/0047—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 the movement of the valves resulting from the sum of the simultaneous actions of at least two cams, the cams being independently variable in phase in respect of each other
    • 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
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/12—Transmitting gear between valve drive and valve
    • F01L1/14—Tappets; Push rods
    • F01L1/146—Push-rods
    • 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
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/20—Adjusting or compensating clearance
    • F01L1/22—Adjusting or compensating clearance automatically, e.g. mechanically
    • F01L1/24—Adjusting or compensating clearance automatically, e.g. mechanically by fluid means, e.g. hydraulically
    • F01L1/2411—Adjusting or compensating clearance automatically, e.g. mechanically by fluid means, e.g. hydraulically by means of a hydraulic adjusting device located between the valve stem and rocker arm
    • 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
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/26—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of two or more valves operated simultaneously by same transmitting-gear; peculiar to machines or engines with more than two lift-valves per cylinder
    • F01L1/267—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of two or more valves operated simultaneously by same transmitting-gear; peculiar to machines or engines with more than two lift-valves per cylinder with means for varying the timing or the lift of the valves
    • 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
    • F01L13/0005—Deactivating valves
    • 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
    • F01L2305/00—Valve arrangements comprising rollers

Definitions

  • the invention relates to an internal combustion engine comprising a poppet valve and a valve actuating mechanism for acting on a stem of the poppet valve to open and close the valve, the valve actuating mechanism including two rotatable cams, a first rocker mounted on a pivot shaft and acting between a first of the two cams and the valve stem, and a second rocker mounted for rotation about a fixed axis and acting between the second of the two cams and the pivot shaft of the first rocker to raise and lower the pivot axis of the first rocker cyclically in synchronism with the rotation of the second cam, whereby the valve is operated in dependence upon the instantaneous sum of the lifts of the two cams.
  • Such valve actuating mechanisms are known per se and are described for example in U.S. Pat. No. 6,854,434, GB Pat. Appln. No. 0519876.7, and U.S. patent application Ser. No. 11/284,725.
  • cylinder deactivation is becoming increasingly common on large displacement gasoline engines, where significant fuel economy improvements can result from running an eight cylinder engine on four cylinders during light load operation. Deactivating one of a pair of intake valves on a diesel engine in order to control in-cylinder swirl levels is also an interesting concept for future research.
  • the present invention therefore seeks to provide a system for controlling valve lift and duration which is additionally capable of deactivating one or more valves per cylinder.
  • an internal combustion engine comprising a poppet valve and a valve actuating mechanism for acting on a stem of the poppet valve to open and close the valve, the valve actuating mechanism including two rotatable cams, a first rocker mounted on a pivot shaft and acting between a first of the two cams and the valve stem, and a second rocker mounted for rotation about a fixed axis and acting between the second of the two cams and the pivot shaft of the first rocker to raise and lower the pivot axis of the first rocker cyclically in synchronism with the rotation of the second cam, whereby the valve is operated in dependence upon the instantaneous sum of the lifts of the two cams, characterised in that an element of the valve actuating mechanism transmitting force from one of the cams to the valve stem is formed in two parts, one part movable by the associated cam and the other transmitting force to the valve stem, a latching mechanism is provided for selectively locking the two parts of the element for movement in unison
  • two cams are used to actuate one or more valves via a summation system, and the valve lift characteristic can be changed by phasing one of the cam lobes relative to the other.
  • Such systems can be arranged such that valve lift will only occur when both cam lobes are on lift and the valve will be closed if either of the cam profiles is on its base circle radius. It follows that there will be some clearance in the system during some portion of the camshaft cycle when both cams are close to their base circle radii, and it is this clearance that provides the opportunity for a valve deactivation system to operate.
  • valve deactivation and cam switching devices are known from the prior art that are designed to operate when the valve is closed (e.g. U.S. Pat. No. 6,196,175 US 2002/0014217 U.S. Pat. No. 6,135,074) but in conventional systems where there is little or no clearance when the valves are closed the switching of the valve deactivation system has to be carefully controlled in order to prevent the switching process from taking place when the valve begins to lift. This would be likely to cause overloading of the locking components and damage to the system. In order to avoid this, the switching of the systems applied to each cylinder of the engine is often controlled independently to make sure each cylinder switches fully whilst the valve is closed.
  • the summation rocker system design requires the rocker system to move whilst the valve is closed and the system is not heavily loaded. This allows a number of different implementations of the present invention, in which use is made of this additional rocker motion to effect the switching of the rocker system to a deactivated mode of operation. This allows the timing of the switch to be controlled such that it will always occur whilst the valve is closed and also offers the opportunity for the deactivation system to be integrated into the design of the rocker system rather than being a totally separate system.
  • FIGS. 1A and 1B are perspective views of two different types of known summation valve trains
  • FIG. 2 is a graph showing the principle of operation of a summation valve train
  • FIGS. 3A , 3 B and 3 C are a section, end view and perspective view, respectively, of a first embodiment of the invention in which a valve deactivation system is located in the position of a lash adjuster,
  • FIGS. 4A , 4 B and 4 C are similar views showing a modification of the valve deactivation system of FIG. 3 .
  • FIGS. 5A and 5B show side and perspective views of another embodiment of the invention.
  • FIGS. 6A , 6 B and 6 C show isometric, side and exploded views of the deactivation system incorporated in the valve train of FIG. 5 ,
  • FIGS. 7A and 7B are isometric and side views, respectively, of a further embodiment of the invention using mechanical valve deactivation
  • FIGS. 8A , 8 B, 8 C and 8 D are respectively a section, an end view, a perspective view and an exploded view of a rocker in FIGS. 7A and 7B ,
  • FIGS. 9A to 9F show end views and views from below of the rocker of FIGS. 7 and 8 in different positions
  • FIGS. 10A and 10B show a side view and a perspective view, respectively, of an embodiment of the invention in which a single rocker is used to actuate two valves through a bridge piece,
  • FIGS. 11A to 11E are a side view, section, plan view from above, perspective view and an exploded view of one of the rockers in FIG. 10 ,
  • FIG. 12 shows the valves and bridge piece operated by the rocker in FIG. 11 .
  • FIGS. 13A and 13B are assembled and exploded perspective views of a further embodiment of the invention.
  • FIGS. 14A to 14C are an exploded view from the opposite end and details of modifications of the embodiment shown in FIG. 13 .
  • FIGS. 15A and 15B are assembled and exploded perspective views of a further embodiment of the invention.
  • FIGS. 16A , 16 B and 16 C are a perspective, plan and exploded view, respectively, of three-part rocker in FIGS. 15A and 15B ,
  • FIGS. 17 A to C are different sections through the rocker of FIG. 16 .
  • FIGS. 17D and 17E are sections similar to the sections of FIGS. 17A and 17B but showing the locking pins in a different position
  • FIGS. 18A , 18 B and 18 C are a perspective view, a section and an exploded perspective view, respectively, of a rocker of a further embodiment of the invention.
  • FIGS. 19A and 19B show a valve train using the rocker of FIG. 18 in the deactivated and activated positions, respectively,
  • FIG. 19C shows a front view of the valve train of FIGS. 19A and 19B .
  • FIG. 20 is a perspective view of the valve train of FIG. 19 .
  • FIG. 21A is a side view of a cam follower embodying the invention.
  • FIG. 21B is a section through the cam follower of FIG. 21A along the section line A-A in FIG. 21A ,
  • FIGS. 21C to 21E are sections along the line B-B of FIG. 21B showing different states of the cam follower
  • FIGS. 22A , 22 B, 22 C and 22 D are a side view, a partially cut away perspective view, a section and an exploded view, respectively, of a further cam follower embodying the present invention.
  • valve train of FIG. 1A is for use in overhead valve engines where the camshaft is located in the cylinder block whilst the valve train of FIG. 1B is for engines with an overhead camshaft.
  • each valve 10 is acted upon by valve-opening rocker 12 , the angular position of which is defined by a first cam profile, and the valve-opening rocker 12 is itself carried by a pivot on a supporting rocker 14 which is moved by a second cam profile.
  • cams mounted on the same or different camshafts have cam followers 16 and 18 which transmit the movement of the two cams to the rockers 12 and 14 by way of push rods 20 and 22 , respectively.
  • the cams are mounted on a common assembled camshaft 30 .
  • a roller follower 32 transmits the motion of one cam to the rocker 14 which is pivoted about a fixed shaft 34 and carries the pivot shaft 36 of the valve opening rockers 12 , each of the latter having a roller follower 38 in contact with a respective cam of the assembled camshaft 30 .
  • FIG. 2 shows the way in which the two cam profiles 40 and 42 are added together in order to produce the valve lift 44 .
  • An additional control spring is normally integrated into the system in order to dictate whether this clearance will occur between the valve tip and its rocker or between one of the cam followers and its associated cam lobe (see GB Patent Appln. No. 0426352.1 and U.S. Ser. No. 11/284,725).
  • phase of the cams acting on the two rockers By varying the phase of the cams acting on the two rockers relative to one another, it is possible to vary the overlap period and hence the event duration.
  • the phase of the valve event can be varied by altering the phase of both cams relative to the crankshaft.
  • the rocker system is not stationary during the clearance phase of the motion, but moves from its valve closing position back to its valve opening position.
  • the proposed designs utilise the clearance in the system and the movement of the rocker system in the clearance phase to effect the valve deactivation.
  • a number of different locations can be selected for integrating a valve deactivation systems into the summation valve trains shown in FIGS. 1A and 1B . In essence it is only necessary to interrupt either one of the paths transmitting motion, be it directly or indirectly, from one of the cams to the valve, to cause the valve to remain closed at all times. In the case of the OHC design shown in FIG. 1B , where a pair of valves is being actuated, the valve deactivation could be applied to one valve or to both valves as required.
  • valve deactivation is effected by preventing transmission of force at the interface between the valve stem and the valve-opening rocker 12 .
  • the rocker design shown in FIG. 3 is intended as a direct replacement for the valve opening rockers 12 for either of the valve trains shown in FIGS. 1A and 1B .
  • the deactivation system is integrated into a clearance adjuster 50 , which is mounted in the end of the rocker 12 and acts on the valve tip.
  • the adjuster 50 comprises a hollow plunger 52 that can slide into the end of the rocker 12 and is biased into contact with the valve stem (not shown in FIG. 3 ) by means of a spring 54 .
  • the opposite end of the spring 54 acts on a ball 56 that can itself slide within an inner sleeve 55 located inside the plunger 52 .
  • the ball 56 which can itself be urged out of the inner sleeve 55 by application of hydraulic pressure serves as part of a latching system which prevents the plunger 52 from being retracted into the end of the rocker 12 .
  • FIG. 3 shows the system in its locked position where the rocker will lift the valve.
  • the lift is transmitted to the valve via the plunger 52 , which is prevented from sliding into its bore in the rocker by the ring of balls 58 connecting it to an inner sleeve 55 which is in turn located by the clearance adjusting screw 60 .
  • the balls 58 are prevented from sliding inwards by the large central ball 56 , which is held against an end stop by a spring and the contact forces of the smaller balls.
  • the valve is deactivated by applying oil pressure to a drilling in the rocker, which acts to force the central ball downwards against the action of the spring 54 .
  • the central ball 56 can only move when there is clearance between the rocker and the valve tip because it has to force the small balls away from the centre in order to pass through.
  • the movement of the small balls pushes the plunger out of the rocker slightly due to the angle of the face on which they locate and this can only happen when the plunger is unloaded.
  • the spring 54 also acts to move the plunger axially to a position where the small balls 58 can move freely.
  • the plunger 52 When the rocker next contacts the valve, the plunger 52 will push the small balls inwards and retract freely into the rocker 12 . If the oil pressure is removed, the large ball will move back against its stop under the action of the spring 54 the next time the system is in clearance. The contact of the small balls 58 on the larger ball 56 ensures that there are only two stable equilibrium positions, with the large ball being held against its upper stop, or against its retaining clip.
  • the latching system is an over-centre arrangement which cannot operate when the rocker is in contact with the valve tip, hence the switch between valve lifting and valve deactivation modes can only occur during the clearance part of the valve train cycle.
  • the system is also of a bi-stable design in that if the rocker is brought into contact with the valve whilst the system is in the process of switching, the contact forces the system into one or other of its stable positions. This avoids any extremely high forces being applied to the components of the latch.
  • This design can be applied to one or both valves of a pair, depending on whether single valve deactivation or cylinder deactivation are required. It would also be possible to switch a pair of valves independently if two separate switched oil feeds were provided—one for each rocker. Although it has been drawn for an OHC application, this design could be simply applied to a pushrod valve train system to achieve valve deactivation. In all cases a control spring is still required to maintain contact between both cam profiles and their respective followers.
  • FIG. 4 An alternative design for the mechanism of FIG. 3 is shown in FIG. 4 in which the large central ball 56 is replaced by a sliding sleeve 66 that holds a ring of balls 58 ′ in engagement with the sliding plunger 52 ′ to lock it into position.
  • the sleeve 66 is moved upwards as viewed hydraulically to release the latch and it moved into the illustrated latching position by a spring 64 .
  • the surface of the sleeve 66 that contacts the balls 58 ′ is profiled in order to give the system a bi-stable characteristic as described above. In other respects, the device will operate in a similar manner to the design in FIG. 3 .
  • FIGS. 5 and 6 is similar to the embodiments of FIGS. 3 and 4 in that it provides a method for disconnecting the valve tip from the valve-opening rocker such that the opening rocker motion is no longer transmitted to the valve.
  • the deactivation system is operated mechanically, rather than by an oil pressure signal.
  • FIGS. 5A and 5B A first method for achieving this objective is shown in FIGS. 5A and 5B where control shafts 70 may be rotated in order to determine which valves are deactivated at any particular time.
  • a lever 72 on a rocker 12 When a lever 72 on a rocker 12 is moved towards the valve by rotating the control shaft 70 , the valve is deactivated. Having different profiled sections on the control shaft to act on each rocker will allow different combinations of valves to be deactivated.
  • FIG. 6 illustrates how the valve deactivation system operates in more detail.
  • a ball-ended clearance adjuster 74 is threaded into a sliding cylinder 76 that has an interrupted external key 78 on both sides and runs in a corresponding slot in the rocker body.
  • a latching plate 82 is located between the lower part of the key 78 on the sliding cylinder 76 and the underside of the body of the rocker 12 , preventing the sliding cylinder 76 from moving and hence lifting the valve.
  • the latch plate 82 may not move quickly enough the avoid contact with the key on the sliding cylinder. In this case, the latch plate 82 will be forced back to its seated position in contact with the underside of the rocker body against the action of the two springs, and no damage to the moving parts will occur.
  • FIGS. 7 and 8 An alternative mechanical valve deactivating system is shown in FIGS. 7 and 8 .
  • the valve can be deactivated by allowing a sliding plunger 94 to move into the rocker instead of transmitting the rocker motion to the valve.
  • Each rocker is fitted with a lever 96 , the position of which determines whether the valve lift will be deactivated. Positioning of the lever 96 close to the pivot point of the rocker 12 minimises its movement relative to the static parts of the cylinder head and a number of fairly simple methods for moving the levers are feasible. One such method is shown in, and will be described below by reference to, FIG. 10 .
  • FIG. 8 show the design of the valve-lifting rocker in more detail.
  • the valve lift is enabled and deactivated via a sliding plate 98 that pivots about a pin 92 mounted in the rocker body.
  • the plate 98 slides against the underside of the rocker body, and has a bore 100 through which the ball-ended plunger 94 for lifting the valve is able to pass.
  • the bore 100 in the plate 98 is aligned with the plunger bore in the rocker, the plunger is free to slide and the valve will be deactivated.
  • Rotating the plate through a small angle about the pin 92 allows it to engage in a recess 102 machined into the plunger 94 , and this will lock the plunger 94 in position to transmit the rocker motion to the valve.
  • An interlock system is provided to ensure that any change from valve activation to valve de-activation may only occur during the clearance phase of the rocker motion. This is achieved by a pin 104 that is fitted to the plunger 94 and passes through a slot 106 in the rocker body, into a profiled slot 108 in the sliding plate 98 .
  • the plunger 94 is loaded by a spring 110 , so that as clearance appears in the rocker system, the plunger will move out of its bore and the pin 104 will move to the bottom of the ‘V’ profile of the slot 108 , rotating the plate to a ‘central’ position between the locked and unlocked positions. As the system approaches the point of valve lift, the clearance reduces and the pin travels up one or other side of the ‘V’, moving the plate into one of its extreme positions.
  • the movement of the plate 98 is determined by a torque spring 112 that acts on the pivot pin 92 of the plate 98 and reacts against the control lever 96 . Moving the control lever therefore determines the direction in which the plate is preloaded by the torque spring 112 , and this in turn determines whether the interlock pin 104 will move up the short or the long side of the ‘V’ slot.
  • FIGS. 9A to 9F show the operation of the interlock system as the system moves from the valve lift position ( FIG. 9A ) through the clearance position ( FIG. 9C ) and into the valve-deactivated position ( FIGS. 9E ).
  • the corresponding views of the underside of the rocker as seen in FIGS. 9B , 9 D and 9 F, respectively, show how the plate engages with the plunger to transmit the rocker motion to the valve.
  • a similar deactivation system can be applied to an engine using bridge pieces to transmit the lift of a single rocker to a pair of valves.
  • the bridge piece design is particularly popular for engines using ‘twisted’ or ‘diamond pattern’ valve arrangements (as shown in FIG. 10 ) where different rocker geometry would be necessary to actuate the valves of each pair individually.
  • FIGS. 10 to 12 show how the deactivation method described by reference to FIGS. 7 to 9 can be used to switch from two-valve operation via a bridge piece to single valve operation. This is achieved by deactivating a plunger 124 that acts on the centre of the bridge 130 and actuating a single valve via an insert 132 that passes through the bridge piece 130 (see FIG. 12 ).
  • the valve lift of the single valve will be less than that of the pair of valves because it is closer to the pivot point of the rocker 12 than the centre of the bridge 130 .
  • FIG. 10 also shows how the control levers 96 on the rockers may be actuated by a simple plate 140 mounted to the cylinder head cover that is free to slide parallel to the camshaft axis.
  • the plate 140 engages the control levers 96 of the rockers via slots, such that changing the position of the plate 140 will cause all of the levers 96 to rotate.
  • the plate is engaged with an eccentric 142 at one end such that rotating the eccentric will cause the plate 140 to move.
  • the design of the valve-lifting rocker may be described more easily with reference to the different views of FIG. 11 .
  • the rocker 12 is fitted with two spherical pads 150 , 152 .
  • the first pad 150 acts on the centre of the bridge piece 130
  • the second pad 152 acts on the separate insert 132 in the bridge piece 130 that opens a single valve 10 B.
  • the first pad 150 is part of the sliding plunger 124 that may be disconnected from the rocker 12 by the valve deactivation system, whilst the second pad 152 is fixed and may be threaded into the rocker 12 for adjustment purposes.
  • FIG. 11 shows the design of the deactivation system for the plunger 124 that acts on the centre of the bridge piece 130 .
  • a moving plate 160 engages with a step on the plunger 124 in order to prevent it from sliding in the rocker, and the plate 160 is provided with an interlock arrangement to ensure that it may only be in one of its two end positions at the point of valve lift. In principle this system operates in an identical manner to that described by reference to FIGS. 7 to 9 .
  • FIG. 12 shows the arrangement of the bridge piece 130 and the insert 132 , which allows a single valve 10 B to be operated through the bridge. Any of the previously described embodiments may be adapted to work with a bridge piece of this type as outlined above.
  • FIGS. 13 and 14 deactivates the valve lift by isolating a pivot 200 of the valve-lifting rocker 12 from the movement of the supporting rocker 14 .
  • FIGS. 13 and 14 illustrate how this may be achieved on an OHV engine by mounting the valve-opening rocker 12 on a separate eccentric sleeve 200 .
  • the eccentric sleeve 200 is mounted for rotation about a fixed pivot shaft 202 , which also supports the second ‘supporting’ rocker 14 .
  • a latching system 210 is integrated with the eccentric 200 in order to connect the eccentric for rotation with the second rocker 14 and removing this connection acts to deactivate the valve lift.
  • the latching system 210 is designed to transmit rotation in only one direction. This is achieved by forming an end surface 214 of a latch pin 212 (see FIGS. 14B and 14C ) with a ramp which terminates in an abrupt step, thereby acting in a manner analogous to a pawl and ratchet.
  • a latch pin 212 see FIGS. 14B and 14C
  • the latch pin is forced against the driving step on the second rocker (see FIG. 14A ) causing the eccentric to rotate with the rocker.
  • the second rocker is still in motion and this causes the latch pin to move away from the driving step on the closing rocker.
  • the contact face 214 of the latch pin 212 and the second rocker 14 are profiled such that the relative motion forces the latch pin into its bore in the eccentric against the action of a spring 216 . As the system approaches the valve opening position, the latch pin 212 moves back into its engaged position under the action of the spring 216 .
  • FIGS. 14B and 14C show the design of the eccentric 200 .
  • FIG. 14B illustrates a locking ball 220 that will prevent the latch pin from returning when it is supplied with oil pressure
  • FIG. 14C shows a mechanical system 230 , shown as being a ball catch, that will always trap the pin 212 in its withdrawn position unless an external force is applied to the end of the pin to re-engage it. This could be achieved with a spring-loaded mechanical system.
  • FIGS. 15A and 15B A similar arrangement is possible for the OHC design where the supporting rocker 314 may be divided into a number of sections ( 314 a, 314 b and 314 c ) as shown in FIGS. 15A and 15B . In this way either one or both of the valves may be deactivated by disconnecting the respective linkages 314 a, 314 c from the central section of the support rocker 314 b.
  • locking may be achieved via a stepped pin 312 .
  • the step of the pin 312 engages with a corresponding step on the central section 314 b of the support rocker 314 during the valve lift, and the two parts move out of contact during the clearance portion of the motion.
  • the stepped pin 312 can be pushed into a disengaged position by supplying oil pressure to a small hydraulic piston located in a bore in the central section 314 b of the rocker.
  • FIG. 17 shows the oil drilling 316 used to deactivate the lift and FIGS. 17A & 17B and FIGS. 17D and 17E show the different positions of the locking pins 312 .
  • FIGS. 17A and 17B show the system in its disengaged position whilst the FIGS. 17C and 17D show the system in its engaged position where the two pistons 318 are pushed fully into the central section 314 b of the rocker and the locking pins 312 are engaged with the drive step on the central section 314 b of the rocker.
  • the stepped locking pins 312 need to be retained in a suitable angular alignment in order to engage properly, so each is provided with a slot 320 into which is engaged a ball 322 to limit the angular rotation of the pin 312 (see FIG. 16C ).
  • a spring 324 behind the pin is designed to act as combined compression and torque spring so that it acts to urge the locking pin 312 out of its bore and to hold it against the end of its angular rotation range.
  • the disengaged pin 312 is designed to move into a position where its flat contact surface is not aligned with that of the centre section 314 of the rocker. This ensures that the pin 312 can only engage when there is some clearance in the system and this prevents the pin starting to engage right at the point of valve lift commencing and causing damage to the parts of the system. Once engaged, the pin will automatically be rotated to the correct position against the action of its spring as the clearance in the system reduces.
  • FIG. 18 deactivates the valve by disconnecting the motion of the cam follower from the rocker system and offers the opportunity for integrating the deactivation system with a control spring for positioning the rocker system during the clearance phase of the cycle.
  • FIG. 18 shows the design for an OHC application, where the valve-operating rocker 412 has been divided in to two sections 412 a and 412 b that are connected by a pivot shaft 414 .
  • the cam follower 416 is mounted into the lower section 412 b of the rocker and is able to move relative to the main section 412 a of the rocker against the action of a control spring 418 that is installed in the main section 412 a of the rocker.
  • the cam follower 416 will be held in contact with the cam and the clearance adjuster 420 will be held in contact with the valve by the control spring 418 .
  • a latch pin 422 may be engaged to transmit the motion of the lower section 412 b to the main section 412 a of the rocker in order to lift the valve. If the pin 422 is held out of contact with an abutment 424 on the main section of the rocker, the section 412 b will continue to move independently of the main section 412 a of the rocker, thereby deactivating the valve lift.
  • FIGS. 19A to 19C illustrate how a simple spring may be integrated with the rocker assembly to hold the pin 422 out of engagement with the abutment 424 .
  • Valve lift is activated by forcing the pin 422 downwards into the path of the abutment 424 via a strip of spring steel 450 installed into the engine cover.
  • the position of the steel strip 450 is determined by its contact with a control shaft 452 mounted in the cover.
  • the control shaft 452 has a number of profiled sections that each contact the steel strips 450 associated with the different rockers.
  • valves The operation of the valves is controlled by the rotation of the control shaft 452 , but it is not necessary for all of the valves to be deactivated at the same time.
  • control shaft 452 By producing the control shaft 452 , as shown in FIG. 20 , with a number of different profiles, it is possible to provide a variety of different control shaft positions that will deactivate different combinations of valves.
  • FIG. 21A to 21E shows how this may be achieved using an over-centre locking system similar to that previously described by reference FIG. 3 .
  • FIG. 21B shows the cam follower 16 in its fully extended position with the large central ball 510 in its upper position to force a ring of smaller balls 512 outwards into a recess in the main body of the cam follower.
  • a hole is provided on the left side of the follower to feed the deactivation oil supply into this recess and force the central ball 510 into its lower position.
  • a second oil drilling is provided on the right hand side to allow lubricating oil into the cam follower.
  • FIGS. 21C to 21E show the arrangement of the balls in the three different positions of the follower.
  • FIG. 21C shows the follower fully extended in order to control the rocker system
  • FIG. 21D shows the follower in its locked position where the ring of locking balls 512 are engaged with the lower face of the cut-out in the follower bore
  • the FIG. 21E shows the follower in its fully compressed state (valve deactivated) where the central ball 510 has been moved into its lower position by oil pressure and the ring of smaller balls 512 have moved inwards in order to pass the edge of the recess.
  • FIG. 22 An alternative design for integrating a deactivation system into a cam follower is shown in FIG. 22 .
  • the valve deactivation in this case is achieved via a pair of splined components 610 , 612 that may either be aligned so that the inner spline will slide into the outer spline, deactivating the valve lift, or misaligned so that the end of the inner spline will contact the top face of the outer spline, transmitting the cam lift to the rocker system.
  • the internally splined component 612 has a helical groove 614 machined into its outer diameter, which is engaged by a ball 616 that is permanently fitted to the body of the cam follower. Oil can be supplied to the cavity below the internally splined component in order to move it to a higher position and this also causes it to rotate because of the helical groove 614 .
  • the upper spline can pass through it without making contact.
  • the two sets of splines are misaligned and so the upper spline cannot enter the lower spline.
  • the lower splined component 612 can only move to its upper position when the valve train is in the clearance portion of the cycle and the cam follower is fully extended. If it should be in the process of movement when it comes into contact with the upper spline, it will simply be forced back into its bore and take up the locked position.
  • a pair of slots in the bore of the follower locates the upper spline 610 and allows it a small range of angular travel. It is preloaded against one side of these slots by a torque spring 618 that is located beneath it in a housing 620 , which also engages into the slots in the follower bore. This allows the upper splined component 610 to rotate with the lower spline when the pair are engaged and the lower spline is forced back into its bore under the action of the cam lift.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Valve Device For Special Equipments (AREA)
US11/744,964 2006-05-19 2007-05-07 Valve actuating mechanism Abandoned US20070266973A1 (en)

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GB0609935.2 2006-05-19
GB0609935A GB2438208A (en) 2006-05-19 2006-05-19 I.c. engine poppet valve actuating mechanism

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US20100294222A1 (en) * 2008-01-22 2010-11-25 Mechadyne Plc Variable valve actuating mechanism with lift deactivation
CN102966391A (zh) * 2012-11-25 2013-03-13 天津大学 双凸轮控制的摇臂机构
CN102966406A (zh) * 2012-11-25 2013-03-13 天津大学 双摇臂控制的凸轮机构
US20140326212A1 (en) * 2010-07-27 2014-11-06 Jacobs Vehicle Systems, Inc. Lost Motion Valve Actuation Systems with Locking Elements Including Wedge Locking Elements
US9133735B2 (en) 2013-03-15 2015-09-15 Kohler Co. Variable valve timing apparatus and internal combustion engine incorporating the same
US20170145876A1 (en) * 2015-11-20 2017-05-25 Man Truck & Bus Ag Variable valve train with a rocker arm
US10487763B2 (en) 2018-04-26 2019-11-26 Ford Global Technologies, Llc Method and system for variable displacement engine diagnostics
US20200011212A1 (en) * 2018-07-03 2020-01-09 Schaeffler Technologies AG & Co. KG Module for a variable-stroke valve drive of an internal combustion engine
US10753303B2 (en) 2018-04-26 2020-08-25 Ford Global Technologies, Llc Method and system for variable displacement engine diagnostics
US10801418B2 (en) 2018-04-26 2020-10-13 Ford Global Technologies, Llc Method and system for variable displacement engine diagnostics
US10851717B2 (en) 2010-07-27 2020-12-01 Jacobs Vehicle Systems, Inc. Combined engine braking and positive power engine lost motion valve actuation system
US11008968B2 (en) 2018-04-26 2021-05-18 Ford Global Technologies, Llc Method and system for variable displacement engine diagnostics

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CN102261283B (zh) * 2010-05-27 2013-10-09 上海尤顺汽车部件有限公司 一种固链式发动机制动装置
EP2975230B1 (de) * 2014-07-15 2018-02-21 Jacobs Vehicle Systems, Inc. Leerlaufventilbetätigungssysteme mit sicherungselementen einschliesslich keilsicherungselementen
DE102017008219A1 (de) 2017-08-31 2019-02-28 Daimler Ag Ventiltrieb für eine Verbrennungskraftmaschine, insbesondere eines Kraftfahrzeugs
CN109779717B (zh) * 2019-03-27 2021-01-05 大连理工大学 一种紧凑型固定式驱动支点
CN109812315A (zh) * 2019-03-27 2019-05-28 大连理工大学 一种高效固定式制动支点
CN109779716B (zh) * 2019-03-27 2021-01-05 大连理工大学 一种紧凑型移动式驱动支点
CN109854326A (zh) * 2019-03-27 2019-06-07 大连理工大学 一种高效移动式制动支点
US11047267B2 (en) * 2019-04-25 2021-06-29 Mechadyne International Ltd. Variable valve lift system
AT524829B1 (de) * 2021-02-18 2023-03-15 Avl List Gmbh Ventilbetätigungsvorrichtung
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US20100294222A1 (en) * 2008-01-22 2010-11-25 Mechadyne Plc Variable valve actuating mechanism with lift deactivation
US8365691B2 (en) * 2008-01-22 2013-02-05 Mechadyne Plc Variable valve actuating mechanism with lift deactivation
US20140326212A1 (en) * 2010-07-27 2014-11-06 Jacobs Vehicle Systems, Inc. Lost Motion Valve Actuation Systems with Locking Elements Including Wedge Locking Elements
US10851717B2 (en) 2010-07-27 2020-12-01 Jacobs Vehicle Systems, Inc. Combined engine braking and positive power engine lost motion valve actuation system
US9790824B2 (en) * 2010-07-27 2017-10-17 Jacobs Vehicle Systems, Inc. Lost motion valve actuation systems with locking elements including wedge locking elements
CN102966391A (zh) * 2012-11-25 2013-03-13 天津大学 双凸轮控制的摇臂机构
CN102966406A (zh) * 2012-11-25 2013-03-13 天津大学 双摇臂控制的凸轮机构
US9133735B2 (en) 2013-03-15 2015-09-15 Kohler Co. Variable valve timing apparatus and internal combustion engine incorporating the same
US10400639B2 (en) * 2015-11-20 2019-09-03 Man Truck & Bus Ag Variable valve train with a rocker arm
RU2723650C2 (ru) * 2015-11-20 2020-06-17 Ман Трак Унд Бас Аг Регулируемый клапанный механизм, имеющий коромысло
US20170145876A1 (en) * 2015-11-20 2017-05-25 Man Truck & Bus Ag Variable valve train with a rocker arm
US10487763B2 (en) 2018-04-26 2019-11-26 Ford Global Technologies, Llc Method and system for variable displacement engine diagnostics
US10753303B2 (en) 2018-04-26 2020-08-25 Ford Global Technologies, Llc Method and system for variable displacement engine diagnostics
US10801418B2 (en) 2018-04-26 2020-10-13 Ford Global Technologies, Llc Method and system for variable displacement engine diagnostics
US11008968B2 (en) 2018-04-26 2021-05-18 Ford Global Technologies, Llc Method and system for variable displacement engine diagnostics
US20200011212A1 (en) * 2018-07-03 2020-01-09 Schaeffler Technologies AG & Co. KG Module for a variable-stroke valve drive of an internal combustion engine
US11193396B2 (en) * 2018-07-03 2021-12-07 Schaeffler Technologies AG & Co. KG Module for a variable-stroke valve drive of an internal combustion engine

Also Published As

Publication number Publication date
EP1857642A1 (de) 2007-11-21
GB0609935D0 (en) 2006-06-28
GB2438208A (en) 2007-11-21

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