Classifications

• • 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
  • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
  • F01L1/12—Transmitting gear between valve drive and valve
  • F01L1/18—Rocking arms or levers
  • F01L1/181—Centre pivot rocking arms
• • 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
• • 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
  • F01L13/065—Compression release engine retarders of the "Jacobs Manufacturing" type
• • 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
  • F01L1/46—Component parts, details, or accessories, not provided for in preceding subgroups
  • F01L2001/467—Lost motion springs
• • 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
  • F01L2013/001—Deactivating cylinders
• • 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
  • F01L2013/10—Auxiliary actuators for variable valve timing
  • F01L2013/105—Hydraulic motors
• • 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
  • F01L2800/01—Starting
• • 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
  • F01L2800/02—Cold running

Definitions

• the instant disclosure relates generally to valve actuation systems and, in particular, to a valve actuation system comprising lost motion components in series along a valve actuation load path, which valve actuation system may be used to implement both cylinder deactivation and auxiliary valve actuations.
• Valve actuation systems for use in internal combustion engines are well known in the art. During positive power operation of an internal combustion engine, such valve actuation systems are used to provide so-called main valve actuation motions to engine valves, in conjunction with the combustion of fuel, such that the engine outputs power that may be used, for example, to operate a vehicle. Alternatively, valve actuation systems may be operated to provide so-called auxiliary valve actuation motions other than or in addition to the main valve actuation motions.
• Valve actuation systems may also be operated in a manner so as to cease operation of a given engine cylinder altogether, i.e., no operation in either main or auxiliary modes of operation through elimination of any engine valve actuations, often referred to as cylinder deactivation.
• these various modes of operation may be combined to provide to provide desirable benefits.
• future emissions standards for heavy duty diesel trucks require a technology that improves fuel economy and reduces emissions output.
• a leading technology that provides both at the same time is cylinder deactivation. It is well documented that cylinder deactivation reduces fuel consumption and increase temperatures that provide for improved aftertreatment emissions control. [0003]
• a known system for cylinder deactivation is described in U.S. Patent No.
• the lost motion mechanism comprises an outer plunger 120 disposed with a bore 112 formed in the body 110 of a valve bridge 100.
• Locking elements in the form of wedges 180 are provided, which wedges are configured to engage with an annular outer recess 172 formed in a surface defining the bore 112.
• an inner piston spring 144 biases the inner plunger 160 into position such that the wedges 180 extend out of openings formed in the outer plunger 120, thereby engaging the outer recess 172 and effectively locking the outer plunger 120 in place relative to the valve bridge body 110.
• any valve actuation motions (whether main or auxiliary motions) applied to the valve bridge via the outer plunger 120 are conveyed to the valve bridge body 110 and ultimately to the engine valves (not shown).
• EVO early exhaust valve opening
• a valve actuation system for providing EEVO may be provided using a rocker arm having a hydraulically-controlled lost motion component in the form of an actuator, such as that illustrated in U.S. Patent No. 6,450,144, an example of which is illustrated in FIG. 19 of the ‘824 patent and reproduced herein as FIG. 2.
• a rocker arm 200 is provide having an actuator piston 210 disposed in a motion imparting end of the rocker am 200.
• the actuator piston 210 is biased out of its bore by a spring 217 such that the actuator piston 210 continuously contacts the corresponding engine valve (or valve bridge).
• Hydraulic passages 231, 236 are provided such that hydraulic fluid can be provided by a control passage 211 to fill the actuator piston bore.
• a cam comprises cam lobes for providing both main and auxiliary valve actuation motions.
• EEVO lost motion combines a normal main event lift with an early raised portion on the same camshaft.
• FIG. 3 a first curve 310 illustrates an idealized version of a main event valve lift that, in this example, has a maximum lift of approximately 14 millimeters.
• a second curve 311 illustrates a typical actual main event as experienced by the engine valve, which would occur when any EEVO motion provided by the cam is lost, e.g., the above-described rocker arm actuator in FIG. 2 is permitted to reciprocate.
• the upper, dashed curve 312 illustrates idealized valve lift if all valve actuation motions provided by the EEVO-capable cam are provided, e.g., when the rocker arm actuator is fully extended.
• the idealized lift 312 includes an EEVO event 313 of approximately 3 mm of valve lift during valve opening that, in practice, translates to approximately 2 millimeters of valve lift 314.
• FIG. 3 also shows occurrence of resetting, whereby the actuator piston is allowed to collapse (i.e., the locked hydraulic fluid in the actuator bore is vented for this cycle of the engine valve), in this example, at approximately 10 mm of lift, thereby causing the normal-lift main event 311 to occur.
• the combination of these two lift events results in a total stroke of approximately 17mm and would place, when being lost by the lost motion mechanism illustrated in FIG. 1, relatively high stresses on the outer plunger spring 146 as it attempts to bias the outer plunger 120 throughout the full 17 mm of travel of the outer plunger 120.
• rocker arm biasing element is configured to provide sufficient force at these speeds to ensure proper contact between the rocker arm and cam.
• otherwise lost EEVO valve actuation motions will be present even up to high engine speeds (e.g., on the order of 2600 rpm).
• the rocker arm biasing element would need to accommodate the higher speed at which EEVO valve actuation motions may still be applied to the rocker arm.
• rocker arm control for lost EEVO valve actuation motions requires application of a high force by the rocker arm biasing element. However, this occurs at a small valve lift where the rocker arm bias spring has its lowest preload.
• cylinder deactivation normally occurs at a lower speed, and throughout a higher lift portion (main valve actuation motions) where the rocker arm biasing element is at an increased preload.
• the challenge of providing a rocker arm biasing element that is capable of both providing a high force at lowest preload (as required by EEVO) and surviving the stresses required during full travel (as required by cylinder deactivation) is difficult to overcome.
• valve actuation system for actuating at least one engine valve in accordance with the instant disclosure.
• the valve actuation system comprises a valve actuation motion source configured to provide a main valve actuation motion and an auxiliary valve actuation motion for actuating the at least one engine valve via a valve actuation load path.
• a lost motion subtracting mechanism is arranged in pre-rocker arm valve train component and configured, in a first default operating state, to convey at least the main valve actuation motion and configured, in a first activated state, to lose the main valve actuation motion and the auxiliary valve actuation motion.
• a lost motion adding mechanism is arranged in a valve bridge and configured, in a second default operating state, to lose the auxiliary valve actuation motion and configured, in a second activated state, to convey the auxiliary valve actuation motion, wherein the lost motion adding mechanism is in series with the lost motion subtracting mechanism in the valve actuation load path.
• auxiliary valve actuation motions include at least one of an early exhaust valve opening valve actuation motion, a late intake valve closing valve actuation motion or an engine braking valve actuation motion.
• the valve actuation system further includes an engine controller configured to operate the internal combustion engine using the lost motion subtracting mechanism and the lost motion adding mechanism. In a positive power mode, the engine controller controls the lost motion subtracting mechanism to operate in the first default operating state and the lost motion adding mechanism to operate in the second default operating state. In a deactivated mode, the engine controller controls the lost motion subtracting mechanism to operate in the first activated operating state and the lost motion adding mechanism to operate in the second default operating state. In an auxiliary mode, the engine controller controls the lost motion subtracting mechanism to operate in the first default operating state and the lost motion adding mechanism to operate in the second activated operating state.
• FIG. 1 illustrates a lost motion mechanism suitable for providing cylinder deactivation in accordance with prior art techniques
• FIG. 2 illustrates a lost motion mechanism suitable for providing auxiliary valve actuation in accordance with prior art techniques
• FIG. 3 is a graph illustrating an example of EEVO valve actuation motions in accordance with the instant disclosure
• FIGs. 4 and 5 are schematic illustrations of embodiments of a valve actuation system in accordance with the instant disclosure
• FIG. 6 illustrates a partial cross-sectional view of an embodiment of a valve actuation system in accordance with embodiment of FIG. 4;
• FIG. 7 is an exploded view of a resetting rocker arm in accordance with the embodiment of FIG. 6;
• FIGs. 8-11 are respective partial top and side cross-sectional views of the resetting rocker arm in accordance with the embodiment of FIGs. 6-8;
• FIG. 12 is a partial cross-sectional view of first embodiment of a valve actuation system in accordance with the embodiment of FIG. 5;
• FIG. 13 is a partial cross-sectional view of a second embodiment of a valve actuation system in accordance with the embodiment of FIG. 5;
• FIG. 14 is a flowchart illustrating a method of operating an internal combustion engine in accordance with the instant disclosure
• FIG. 15 is a schematic illustration of an embodiment of a valve actuation system in accordance with a variation of the valve actuation system depicted in FIG. 4 and in accordance with the instant disclosure;
• FIG. 16 is a side view of an embodiment of a valve actuation system in accordance with the embodiment of FIG. 15;
• FIG. 17 is a side, cross-sectional view of the embodiment in accordance with FIG. 16.
• FIG. 18 is a side, cross-sectional view of the LM+ mechanism of FIG. 17 illustrated in greater detail.
• FIG. 4 schematically illustrates a valve actuation system 400 in accordance with the instant disclosure.
• the valve actuation system 400 comprises a valve actuation motion source 402 that serves as the sole source of valve actuation motions (i.e., valve opening and closing motions) to one or more engine valves 404 via a valve actuation load path 406.
• the one or more engine valves 404 are associated with a cylinder 405 of an internal combustion engine.
• each cylinder 405 typically has at least one valve actuation motion source 402 uniquely corresponding thereto for actuation of the corresponding engine valve(s) 404.
• an internal combustion engine may comprise, and often does, more than one cylinder and the valve actuation systems described herein are applicable to any number of cylinders for a given internal combustion engine.
• the valve actuation motion source 402 may comprise any combination of known elements capable of providing valve actuation motions, such as a cam.
• the valve actuation motion source 110 may be dedicated to providing exhaust motions, intake motions, auxiliary motions or a combination of exhaust or intake motions together with auxiliary motions.
• the valve actuation motion source 402 may comprise a single cam configured to provide a main valve actuation motion (exhaust or intake) and at least one auxiliary valve actuation motion.
• the at least one auxiliary valve actuation motion may comprise an EEVO valve event and/or a compression-release engine braking valve event.
• the at least one auxiliary valve actuation motion may comprise a late intake valve closing (LIVC) valve event.
• LIVC late intake valve closing
• the valve actuation load path 406 comprises any one or more components deployed between the valve actuation motion source 402 and the at least one engine valve 404 and used to convey motions provided by the valve actuation motion source 402 to the at least one engine valve 404, e.g., tappets, pushrods, rocker arms, valve bridges, automatic lash adjusters, etc. Further, as shown, the valve actuation load path 406 also includes a lost motion adding (LM+) mechanism 408 and a lost motion subtracting (LM-) mechanism 410.
• LM+ lost motion adding
• LM- lost motion subtracting
• an LM+ mechanism is a mechanism that defaults to or is “normally” in a state (i.e., when a controlling input is not asserted) in which the mechanism does not convey any auxiliary valve actuation motions applied thereto and may or may not convey any main valve actuation motions applied thereto.
• a state i.e., when a controlling input is not asserted
• the mechanism does convey any auxiliary valve actuation motions applied thereto and also conveys any main valve actuation motions applied thereto.
• an LM- mechanism is a mechanism that defaults to or is “normally” in a state (i.e., when a controlling input is not asserted) in which the mechanism does convey any main valve actuation motions applied thereto and may or may not convey any auxiliary valve actuation motions applied thereto.
• a state i.e., when a controlling input is not asserted
• the mechanism does not convey any valve actuation motions applied thereto, whether main or auxiliary valve actuation motions.
• an LM+ mechanism when activated, is capable of adding or including valve actuation motions relative to its default or normal operating state, whereas an LM- mechanism, when activated, is capable of subtracting or losing valve actuation motions relative to its default or normal operating state.
• lost motion mechanisms that may serve as LM+ or LM- mechanisms are well known in the art, including hydraulically- or mechanically-based lost motion mechanisms that may be hydraulically-, pneumatically-, or electromagnetically-actuated.
• the lost motion mechanism depicted in FIG. 1 and taught in U.S. Patent No. 9,790,824 is an example of a mechanically locking LM- mechanism that is hydraulically-controlled.
• the locking elements 180 are received in the outer recess 772 thereby “locking” the outer plunger 120 to the body 120 such that actuation motions applied thereto are conveyed.
• the locking elements 180 are permitted to retract thereby “unlocking” the outer plunger 120 from the body 120 such that actuation motions applied thereto are not conveyed or lost.
• 6,450,144 (the teachings of which are incorporated herein by this reference), is an example of a hydraulically-based LM+ mechanism that is hydraulically- controlled.
• the actuator piston 210 in the absence of hydraulic fluid input to the passages 231, 236 (i.e., in the default state), the actuator piston 210 is free to reciprocate in its bore such that any actuation motions applied thereto that are lesser in magnitude than the maximum distance that the actuator piston 210 can retract into its bore (the actuator piston stroke length) are not conveyed or lost, whereas any actuation motions applied thereto that are greater than the actuator piston stroke length are conveyed.
• an engine controller 420 may be provided and operatively connected to the LM+ and LM- mechanisms 408, 410.
• the engine controller 420 may comprise any electronic, mechanical, hydraulic, electrohydraulic, or other type of control device for controlling operation of the LM+ and LM- mechanisms 408, 410, i.e., switching between their respective default and activated operating states as described above.
• the engine controller 420 may be implemented by a microprocessor and corresponding memory storing executable instructions used to implement the required control functions, including those described below, as known in the art.
• the engine controller 420 may include peripheral devices, intermediate to engine controller 420 and the LM+ and LM- mechanisms 408, 410, that allow the engine controller 420 to effectuate control over the operating state of the LM+ and LM- mechanisms 408, 410.
• peripheral devices may include suitable solenoids, as known in the art.
• FIGs. 5 and 15 illustrate valve actuation systems 400’, 1500 in which like reference numerals refer to like elements as compared to FIG. 4, where the LM- mechanism 410, 410’ is arranged closer to the valve actuation motion source 402 than the LM+ mechanism 408, 408’.
• Examples of the system of FIG. 5 are described in further detail below with reference to FIGs. 12 and 13, and an example of the system of FIG. 15 is described in further detail below with reference to FIGs. 16-18.
• the LM+ mechanism 408 is in series along the valve actuation load path 406 with the LM- mechanism 410 in all operating states of the LM+ mechanism 408. That is, whether the LM+ mechanism 408 is in its default state or in its activated state as described above, any main valve actuation motions provided by the valve actuation motion source 402 are conveyed by the LM+ mechanism 408 to the LM- mechanism 410. However, once again, this is not a requirement, as illustrated in FIG. 5 where the LM+ mechanism 408 is illustrated either in series or not in series with the LM- mechanism 410 as a function of the operating state of the LM+ mechanism 408.
• the LM+ mechanism 408 when the LM+ mechanism 408 is in its default operating state, i.e., when it is controlled to lose any auxiliary valve actuation motions applied thereto, the LM+ mechanism 408 plays no role in conveying main valve actuation motions conveyed by the LM- mechanism 410; this is illustrated by the solid arrow between the LM- mechanism 410 and the engine valve(s) 404. In effect, in this state, the LM+ mechanism 408 is removed from the valve actuation load path 406 as depicted in FIG. 5.
• the LM+ mechanism 408 when the LM+ mechanism 408 is in its activated operating state, i.e., when it is controlled to convey any auxiliary valve actuation motions applied thereto, the LM+ mechanism 408 participates in the conveyance of both the main valve actuation motions and the auxiliary valve actuation motions that are received from the LM- mechanism 410, thereby effectively placing the LM+ mechanism 408 in series therewith; this is illustrated by the dashed arrows between the LM- mechanism 410 and the LM+ mechanism 408, and the LM+ mechanism 408 and the engine valve(s) 404.
• valve actuation systems 400, 400’ of FIGs. 4 and 5 facilitate operation of the cylinder 405, and consequently the internal combustion engine, in a positive power mode, a deactivated mode or an auxiliary mode in systems having a single valve actuation motions source 402 providing all valve actuation motions to the engine valve(s) 404. This is further described with reference to the method illustrated in FIG. 14.
• LM+ and LM- mechanisms are arranged in a valve actuation load path.
• the LM- mechanism is configured, in a first default operating state, to convey at least main valve actuation motions applied thereto and configured, in a first activated state, to lose any main valve actuation motion and the auxiliary valve actuation motion applied thereto.
• the LM+ mechanism is configured, in a second default operating state, to lose any auxiliary valve actuation motions applied thereto and configured, in a second activated state, to convey the auxiliary valve actuation motion, wherein the LM+ mechanism is in series with the LM- mechanism in the valve actuation load path at least during the second activated state.
• processing proceeds at any of blocks 1406-1410, where engine is respectively operated in a positive power mode, a deactivated mode or an auxiliary mode based on control of the operating states of the LM+ and LM- mechanisms.
• the LM- mechanism is placed in its first default operating state and the LM+ mechanism is placed in its second default operating state.
• the LM+ mechanism will not convey any auxiliary valve actuation motions but may convey any main valve actuation motions (depending on whether the LM+ mechanism is arranged as in FIG. 4 or FIG. 5) that are conveyed by the LM- mechanism.
• the net effect of this configuration is that only main valve actuation motions are conveyed to the engine valve(s), as required for positive power operation.
• the LM- mechanism in order to operate the engine in the deactivated mode, the LM- mechanism is placed in its first activated operating state and the lost motion adding mechanism is in its second default operating state. In this mode, then, the LM- mechanism will not convey any valve actuation motions applied thereto. As a result, the corresponding cylinder will be deactivated to the extent that no valve actuation motions will be conveyed to the engine valve(s). Given this operation of the LM- mechanism, the operating state of the LM+ mechanism will have no effect on the engine valve(s). However, in a presently preferred embodiment, during deactivated mode operation, the LM+ mechanism placed in its second default operating state.
• the LM- mechanism in order to operate the engine in the auxiliary mode, the LM- mechanism is placed in its first default operating state and the LM+ mechanism is placed in its second activated operating state. In this mode, then, the LM+ mechanism will convey any auxiliary valve actuation motions and any main valve actuation motions that are conveyed by the LM- mechanism.
• the net effect of this configuration is that both main valve actuation motions and auxiliary valve actuation motions are conveyed to the engine valve(s), thereby providing for whatever auxiliary operation is provided by the particular auxiliary valve actuation motions, e.g., EEVO, LIVC, compression- release engine braking, etc.
• FIG. 6 illustrates a partial cross-sectional view of a valve actuation system 600 in accordance with the embodiment of FIG. 4.
• the system 600 comprises a valve actuation motion source 602 in the form of a cam operatively connected to a rocker arm 604 at a motion receiving end 606 of the rocker arm 604.
• a rocker arm biasing element 620 e.g., a spring
• reacting against a fixed surface 622 may be provided to assist in biasing the rocker arm 604 into contact with the valve actuation motion source 602.
• the rocker arm 604 rotationally reciprocates about a rocker shaft (not shown), thereby imparting valve actuation motions provided by the valve actuation motion source, via a motion imparting end 608 of the rocker arm 604, to a valve bridge 610.
• the valve bridge 610 is operatively connected to a pair of engine valves 612, 614.
• the valve bridge 610 comprises a LM- mechanism 616 (locking piston) of the type illustrated and described in FIG. 1 above, whereas the rocker arm 604 includes a FM+ mechanism 618 (actuator) of the type substantially similar to that illustrated and described above relative to FIG. 2.
• the FM+ mechanism 618 comprises an actuator piston 702 that is attached to a retainer 703 such that the actuator piston 702 is slidably arranged on a lash adjustment screw 704. Further details of the FM+ mechanism 618 are described with reference to FIG. 9 below.
• the lash adjustment screw 704 is threadedly fastened in an actuator piston bore 710 such that the LM+ mechanism 618 is arranged in a lower portion of the actuator piston bore 710.
• a locking nut 704 is provided to secure the lash adjustment screw 704 at its desired lash setting in use.
• FIG. 7 also illustrates a resetting assembly 712 that is arranged within in a resetting assembly bore 724, which includes openings on the top and bottom (not shown) of the rocker arm 604.
• the resetting assembly 712 comprises a reset piston 714 slidably arranged within the resetting assembly bore 724.
• a resetting piston spring 715 is arranged above the resetting piston 714 and a lower end of the resetting piston spring 716 is secured to the resetting piston 714 using a c-clip 718 or other suitable component.
• a washer 720 is arranged at an upper end of the resetting piston spring 716.
• the resetting assembly 712 is maintained in the resetting assembly bore 724 by a spring clip 722, as known in the art.
• the resetting piston spring 716 biases the resetting piston 714 out of the lower opening of the resetting assembly bore 724 such that the resetting piston 714 is capable of contacting a fixed surface (not shown in FIG. 7).
• the rocker arm 604 reciprocates, the resetting piston 714 slides within the resetting assembly bore 724 in a controllable fashion dictated by rotation of the rocker arm 604.
• the resetting piston 714 may be configured such that an annular channel 715 formed in the resetting piston registers with a resetting passage 802 (FIG. 8) to effectuate a reset of the LM+ mechanism 618, as described in further detail below.
• FIG. 7 further illustrates an upper hydraulic passage 730 formed in the rocker arm 604 that receives a check valve 732.
• the upper hydraulic passage 730 provides hydraulic fluid (provided by a suitable supply passage formed in a rocker shaft, not shown) to the actuator piston bore 710 to control operation of the LM+ mechanism 618.
• a threaded plug 734 or similar device may be employed.
• FIG. 7 also illustrates a rocker arm bushing 740 that may be inserted in a rocker shaft opening 742 and over a rocker shaft as known in the art.
• a cam follower 744 may be mounted on a cam follower axle 746 arranged within a suitable opening 748.
• the actuator piston 702 of the LM+ mechanism 618 includes hydraulic passages 904, 906 that permit hydraulic fluid to be supplied to the LM- mechanism 616 via the actuator piston 702.
• a lower hydraulic passage 908 formed in the rocker arm 604 receives hydraulic fluid from a supply channel in the rocker shaft (not shown) and routes the hydraulic fluid to a lower portion of an actuator piston bore 710.
• the actuator piston 702 comprises an annular channel 910 formed in a sidewall surface thereof that registers with the hydraulic supply passage 908 throughout the entire stroke of the actuator piston 702.
• the annular channel 910 communicates with a horizontal passage 904 and a vertical passage 906 formed in the actuator piston 702.
• the vertical passage 906 directs hydraulic fluid to the swivel 706 having an opening formed therein for the passage of the hydraulic fluid to the LM- mechanism 616. In this manner, hydraulic fluid may be selectively supplied as a control input to the LM- mechanism 616.
• the LM+ mechanism 618 comprises the lash adjustment screw 704 extending into the actuator piston bore 710.
• An actuator piston spring 918 is disposed between the lash adjustment screw 704 and the actuator piston 702 and abuts a lower surface of a shoulder 920 formed in the lash adjustment screw 704, thereby biasing the actuator piston 702 out of the actuator piston bore 710.
• the actuator piston 702 is fastened via suitable threading to a retainer 703 that engages with an upper surface of the lash adjustment screw shoulder 920, thereby limiting the outward stroke of the actuator piston 702, as described in further detail below.
• FIGs. 8 and 9 further illustrate (in phantom in FIG. 9) the upper hydraulic passage 730 formed in the rocker arm 604 for selectively supplying hydraulic fluid (e.g., via a high speed solenoid, not shown) to the actuator piston bore 710 above the actuator piston 702.
• the check valve 732 is provided in a widened portion 730’ of the upper hydraulic passage 730 to prevent back flow of hydraulic fluid from the actuator piston bore 710 back to the supply passage feeding the upper hydraulic passage 730.
• a high-pressure chamber in the actuator piston bore 710 may be formed between the check valve 732 and the actuator piston 702 such that a locked volume of hydraulic fluid maintains the actuator piston 702 in an extended (activated) state.
• valve actuation systems in which a single valve actuation motion source provides both main and auxiliary valve actuation motions may require the ability to reset in order to avoid over-extension of the engine valve(s) during combined auxiliary and main valve actuation motions.
• venting of the locked volume of hydraulic fluid and reset of the actuator piston 702 is provided through operation of the resetting assembly 712.
• a resetting passage 802 is provided in fluid communication with that portion of the actuation piston bore 710 forming the high-pressure chamber with the actuator piston 702, and the resetting piston bore 804.
• the resetting piston 714 is effectively a spool valve having an end extending out of the bottom of the rocker arm 604 under bias of the resetting piston spring 716.
• the resetting piston 714 is of sufficient length and the resetting piston spring 716 has sufficient stroke to ensure that the resetting piston 714 continuously contacts a fixed contact surface 1002 throughout all positions of the rocker arm 604.
• the rocker arm 604 is at base circle relative to the cam 602 (i.e., rotated to the fullest extent toward the cam 602).
• the annular channel 715 is not aligned with the resetting passage 802 (hidden behind the upper hydraulic passage 730 as shown in FIGs. 10 and 11) such that an outer diameter of the resetting piston 714 seals off communication with resetting passage 802, thereby maintaining a trapped volume of fluid (when provided) in the actuator piston bore 710.
• the rocker arm 604 rotates at higher valve lifts (e.g., at or above the reset height shown in FIG. 3) as shown in FIG.
• the resetting piston 714 pivots about its contact point with the fixed surface 1002 and slides relative to the resetting piston bore 804 such that the annular channel 715 registers with the resetting passage 802, thereby permitting the trapped hydraulic fluid to flow through the annular channel 715, into a radial hole 1004 formed in the resetting piston 714 and vent through the top of an axial passage 1006 (shown in phantom) formed in the resetting piston 714.
• the rocker arm 604 once again rotates back following the high lift event, as in FIG. 10
• the resetting piston 714 translates in its bore 804 and once again seals off the resetting passage 802 thereby permitting refill of the actuator piston bore 710.
• the resetting assembly 712 illustrated in FIGs. 6-11 is configured to maintain constant contact with the fixed contact surface 1002.
• the resetting assembly could instead comprise a poppet-type valve that contacts a fixed surface only when the required reset height is achieved.
• the rocker arm biasing element 620 may be provided to assist in biasing the rocker arm 604 into contact with the cam 602.
• a feature of the disclosed system 600 is that individually, neither the rocker arm biasing element 620 nor the actuator piston spring 918 is configured to individually provide sufficient force to bias the rocker arm 604 into contact with the cam 602 throughout substantially all operating conditions.
• the rocker arm biasing element 620 and the actuator piston spring 918 are selected to work in combination for this purpose throughout substantially all operating conditions for the rocker arm 604.
• the actuator piston spring 918 provide a high force only during relatively low lift valve actuation motions (e. g.
• the biasing force applied by the actuator piston spring 918 could cause the actuator piston 702 to push against the LM- mechanism 616 with significant force.
• the LM- mechanism 616 is a mechanical locking mechanism such as the described with reference to FIG. 1 , such force could be strong enough to interfere with the ability of the locking elements 180 to extend and retract, and thereby prevent locking and unlocking of the LM- mechanism 616.
• the travel limit imposed by the lash adjustment screw shoulder 920 on the actuator piston 702 prevents such excessive loading on the LM- mechanism 616, thereby preserving normally-provided lash space within the LM- mechanism 616 that permits the locking elements 180 to freely extend/retract as needed.
• the extension of the actuator piston 702 by the actuator piston spring 918 though relatively small, nonetheless reduces the range stress that the outer plunger spring 146 will have to endure.
• the actuator piston spring 918 can be a high force, low travel spring that provides the high force that is particularly needed for low lift, potentially high speed valve actuation motions.
• This burden sharing by the actuator piston spring 918 and the outer plunger spring 146 could also alleviate the need for the rocker arm biasing element 620 to provide a high preload, and permits design of the rocker arm biasing element 620 to be focused on the lower speed, higher lift portion for the main valve actuation motions that occur during deactivated state operation, which is a less stringent design constraint.
• FIG. 12 illustrates a partial cross-sectional view of a valve actuation system 1200 in accordance with the embodiment of FIG. 5.
• the valve actuation motion source comprises a cam (not shown) operatively connected at a motion receiving end 1206 of a rocker arm 1204 via a push tube 1202 and an intervening LM- mechanism 1216 of the type illustrated and described in FIG. 1 above.
• the rocker arm 1204 rotationally reciprocates about a rocker shaft (not shown), thereby imparting valve actuation motions provided by the valve actuation motion source, via a motion imparting end 1208 of the rocker arm 1204, to a valve bridge 1210.
• valve bridge 1210 is operatively connected to a pair of engine valves 1212, 1214.
• the rocker arm 1204 comprises a LM+ mechanism 1218 of the type substantially similar to that illustrated and described above relative to FIG. 2.
• hydraulic fluid is provided to the LM- mechanism 1216 via suitable passages formed in the rocker shaft and rocker arm 1204 and ball joint 1220.
• hydraulic fluid is provided to the LM+ mechanism 1218 via suitable passages formed in the rocker shaft and rocker arm 1204.
• the check valve 732 of the prior embodiment is replaced by a control valve 1222 to establish the hydraulic lock required to maintain the actuator piston in an extended state.
• the embodiment of FIG. 12 is further characterized by the arrangement of the LM+ mechanism 1218 to interact with only a single engine valve 1214 via a suitable bridge pin 1224.
• the LM- mechanism 1216 includes a relatively strong spring to outwardly bias the outer plunger of the locking mechanism against the pushrod 1202 so that the pushrod 1202 is biased into contact with a cam and so that the rocker arm is biased in direction of the engine valves 1212, 1214.
• the outer plunger of the LM- mechanism 1216 is not travel limited during engine operation (as opposed to engine assembly, where imposing travel limits on the LM- mechanism 1216 facilitates assembly).
• the actuator piston When in the extended (activated) state, however, the actuator piston will not only convey the auxiliary valve actuation motions applied thereto, but will also convey the main valve actuation motions that are applied thereto to its corresponding engine valve 1214.
• the LM+ mechanism 1218 is placed in series with the LM- mechanism 1216 during the activated state of the actuator piston as described above relative to FIG. 5.
• FIG. 13 illustrates a partial cross-sectional view of a valve actuation system 1300 in accordance with the embodiment of FIG. 5.
• the embodiment illustrated in FIG. 13 is substantially identical to the embodiment of FIG. 12 with the exception that the spherical joint 1220 is replaced with an outwardly biased, travel limited, sliding pin 1320.
• the outer plunger spring of the LM- mechanism 1216 is preferably designed with low preload during zero or low valve lifts (e.g., on base circle), and has a spring rate required to get the peak forces for controlling the full range of motion of the rocker arm 1204 over main valve actuation motions during deactivated mode operation.
• a sliding pin spring 1322 used to outwardly bias the sliding pin 1320 is configured with a comparatively high preload and short stroke (substantially similar to the actuator piston spring 918 discussed above). Because the sliding piston 1320 is able to slide within its bore, the sliding piston 1320 includes an annular channel 1334 and radial opening 1336 aligned therewith such that registration of the annular channel 1334 with a fluid supply passage throughout the full stroke of sliding piston 1320 ensures continuous fluid communication between the rocker arm 1204 and the LM- mechanism 1216. Additionally, a stroke adjustment screw 1338 serves to limit travel of the sliding pin 1320 out of it bore toward the LM- mechanism 1216.
• the stroke adjustment screw 1338 prevents the full force of the sliding pin spring 1322 from being applied to the LM- mechanism 1216, which would otherwise be overloaded, potentially interfering with operation thereof.
• stroke provided by the stroke adjustment screw 1338 i.e., equal to the motion that must be lost by the LM+ mechanism during its default operating state
• the lash provided to the locking elements within the LM- mechanism 1216 may be selected to ensure proper operation thereof, as described previously.
• the assembly of the sliding pin 1320, sliding pin spring 1322 and stroke adjustment screw 1338 constitute a portion of the LM+ mechanism in this embodiment.
• the LM- mechanism (more specifically, an element or component thereof) may be biased into an extended position and the LM+ mechanism (again, more specifically, an element or component thereof) may be biased into a retracted position.
• the extended position of the LM- mechanism may be travel limited.
• the LM- mechanism may be biased by a first force into an extended position and the LM+ mechanism may be biased by a second force also into an extended position.
• the first biasing force is preferably greater than the second biasing force.
• the extended position of the LM- mechanism may be travel limited.
• the LM- mechanism may be biased into an extended position and the LM+ mechanism may also be biased into an extended position. In this case, however, the extended position of the LM+ mechanism is travel limited.
• a possible benefit of limiting the travel of the LM+ mechanism is to allow zero load on the valvetrain on while on cam base circle to reduce bushing wear.
• a system 1500 may be provided in which the LM- mechanism 410’ is arranged closer along the valve actuation motion path 406 to the valve actuation motion source 402 than the LM- mechanism 408’.
• the LM+ mechanism 408’ shown in FIG. 15 is always in series with the LM- mechanism 410’ regardless of the operating state (default or activated) of the LM+ mechanism 408’ such that the LM+ mechanism 408’ always plays a role in conveying main valve actuation motions conveyed by the LM- mechanism 410’ and is never removed from the valve actuation load path 406.
• the LM+ mechanism 408’ when the LM+ mechanism 408’ is in its default operating state, the LM+ mechanism 408’ is configured to lose any auxiliary valve actuation motions, but to convey an main valve actuation motions, applied thereto by the valve actuation motion source 402 and the LM- mechanism 408’.
• the LM+ mechanism 408’ when the LM+ mechanism 408’ is in its activated operating state, i.e., when it is controlled to convey any auxiliary valve actuation motions applied thereto, the LM+ mechanism 408’ participates in the conveyance of both the main valve actuation motions and the auxiliary valve actuation motions that are received from the valve actuation source 402 and LM- mechanism 410’.
• the valve actuation system 1500 facilitates operation of the cylinder 405, and consequently the internal combustion engine, in a positive power mode, a deactivated mode or an auxiliary mode (e.g., engine braking) in systems having a single valve actuation motions source 102 providing all valve actuation motions to the engine valve(s) 404. That is, the system 1500 is capable of implementing the method illustrated with reference to FIG. 14 and as described above. In this instance, however, the provisioning of the LM- and LM+ mechanisms at block 1402 occurs, respectively, in a pre- rocker valve train component and a valve bridge as described in further detail below.
• FIGs. 16-18 illustrate a valve actuation system 1600 in accordance with the embodiment of FIG. 15.
• the valve actuation system 1600 includes a LM- mechanism 1602 disposed in or on a pre-rocker arm valve train component and a LM+ mechanism 1604 disposed in a valve bridge.
• a pre-rocker arm valve train component may comprise any valve train component deployed, within a valve train, between a valve actuation motion source (e.g., a cam; not shown) and a rocker arm 1620.
• a valve actuation motion source e.g., a cam; not shown
• this may include devices known in the art such as pushrods, tappets, roller followers, etc.
• the pre-rocker arm valve train component comprises a pushrod 1610 that, in turn, is operatively connected to a roller follower 1612 establishing contact between the pushrod 1610 and a cam (not shown).
• the LM- mechanism 1602 is mounted on an upper end of the pushrod 1610 such that the LM- mechanism 1602 in operatively connected with both the pushrod 1610 and rocker arm 1620.
• the rocker arm 1620 is mounted on a rocker shaft (not shown) for reciprocating movement thereon.
• the rocker arm 1620 is operatively connected to a valve bridge 1630 in which the LM+ mechanism 1604 is deployed.
• valve bridge 1630 is operative connected to a two or more engine valves 1642, 1644 (intake or exhaust valves) that are biased into a closed position by corresponding valve springs 1646, 1648.
• FIG. 16 further illustrates a fixed reaction surface 1650 that contacts an upper end of the LM- mechanism 1602, as described in further detail below.
• the pushrod 1610 has the LM- mechanism 1602 mounted thereon.
• the LM- mechanism 1602 comprises a housing 1702 mounted on the pushrod 1610 through an interference fit or threaded engagement between a stud 1704 extending away from a base wall 1703 of the housing 1702 and an interior diameter 1705 of the pushrod 1610.
• the housing 1702 may be integrally formed as a portion of the pushrod 1610 or the pushrod 1610 may be inserted into a receptacle formed on an exterior of the base wall 1703 of the housing 1702.
• a closed housing bore 1706 is formed the housing 1702 and is configured to receive an outer plunger 1708, an inner plunger 1712, an inner plunger spring retainer 1714, an inner plunger spring 1716, an outer plunger spring 1709, and one or more locking elements 1718, illustrated in this embodiment as wedges.
• the outer plunger spring 1709 disposed within the housing bore 1706 and between the base wall 1703 and the outer plunger 1708, biases the outer plunger 1708 upward in the housing bore 1706 (as illustrated in FIG. 17).
• the inner plunger 1712 is disposed in an inner bore 1710 formed in the outer plunger 1708.
• the inner plunger spring 1716 disposed between the inner plunger spring retainer 1714 (which is affixed to and closes off a lower end of the inner bore 1710) and the inner plunger 1712, bias the inner plunger 1712 upward in the inner bore 1710. Upward travel of the inner plunger 1712 is limited by a stop surface 1726 formed at an upper end of the inner bore 1710.
• the outer plunger 1708 includes openings extending through the sidewall of the outer plunger 1708 in which the wedges 1718 are disposed, which wedges 1718 are configured to engage with an annular outer recess 1720 formed in a surface defining the housing bore 1706.
• a bias spring 1722 is disposed between and in contact with a flange 1724, formed on and radially extending away from an outer surface of the housing 1702, and the fixed contact surface 1650.
• the fixed contact surface 1650 is configured to permit passage to the outer plunger 1708 into contact with a lash adjustment screw 1730 disposed on the rocker arm 1620 while still engaging with an upper end of the bias spring 1722.
• the bias spring 1722 is provided to manage the inertia of the pushrod 1610 and the LM- mechanism 1602 as they reciprocate according to the valve actuation motions applied to the pushrod 1610, and to ensure that the pushrod 1610 (via the roller follower 1612 in this example) maintains contact with the valve actuation motion source.
• Use of the fixed contact surface 1650 for this purpose prevents the relatively large bias applied by the bias spring 1722 from being also applied to the LM+ mechanism 1604 (via the rocker arm 1620) and interfering with operation thereof.
• the outer plunger spring 1709 is a relatively light spring sufficient to bias the outer plunger 1708 into contact with the rocker arm 1620/lash adjustment screw 1730 but not so strong, once again, as to interfere with operation of the LM+ mechanism 1604.
• a rocker shaft (not shown) may be provided with channels for supplying pressurized hydraulic fluid to hydraulic passages 1736, 1738 formed in the rocker arm 1620.
• supply of such hydraulic fluid may be controlled through the use of suitable solenoids (not shown) under supervision of the controller 420.
• the hydraulic passages 1736, 1738 route hydraulic fluid to respective ones of the LM- mechanism 1602 and the LM+ mechanism 1604.
• the respective default/activated states of the LM- and LM- mechanisms 1602, 1604 may be likewise controlled.
• the rocker arm 1620 is equipped with a lash adjustment screw 1730, as known in the art having a first fluid passage 1734 formed therein and terminating in a ball joint 1732.
• the ball joint 1732 is formed to engage a complementarily configured upper surface of the outer plunger 1708 such that fluid communication between the first fluid passage 1734 and the inner bore 1710 is provided throughout all operations of the valve actuation system 1600.
• the first hydraulic passage 1736 is in fluid communication with the first fluid passage 1734 such that hydraulic fluid may be selectively provided as a control input to the LM- mechanism 1602 as described above.
• the rocker arm 1620 is equipped, in this example, with a ball joint 1742 having a second fluid passage 1740 formed therein and in communication with the second hydraulic passage 1738.
• the ball joint 1742 is coupled to a swivel or e-foot 1744 having an opening 1746 formed therein such that fluid communication is continuously provided between the first fluid passage 1740 and the LM+ mechanism 1604.
• this continuous fluid communication permits hydraulic fluid to be selectively provided as a control input to the LM+ mechanism 1604 as described above.
• the LM+ mechanism 1604 comprises lost motion piston 1802 disposed in a closed, centrally-formed bore 1804 in the valve bridge 1630.
• the lost motion piston 1802 comprises a piston opening 1803 providing fluid communication between the first fluid passage 1740/opening 1746 and an interior bore 1813 formed in the lost motion piston 1802.
• the lost motion piston 1802 further comprises a check valve assembly comprising a check disc (or ball) 1802, a check spring 1808, a check spring retainer 1810 and a retainer clip 1812 disposed in the bore 1813.
• the retainer clip 1812 maintains the check spring retainer 1810 in a fixed position within the bore 1813 such that the check spring 1808 continuously biases the check disc 1806 into contact with an upper wall of the lost motion piston 1802, thereby sealing the first fluid passage 1740 from the bore 1813 in the absence of sufficiently pressurized hydraulic fluid provided from the first fluid passage 1740.
• the lost motion piston 1802 is biased out of the bore 1804 and into contact with the swivel 1744 by a piston spring 1814 disposed in the bore 1804, thereby ensuring continuous contact, and therefore continuous fluid communication, between the lost motion piston 1802 and the swivel 1744.
• the lost motion piston 1802 is configured to travel a distance (lost motion lash) that is at least as large as any auxiliary valve actuation motions applied thereto by the rocker arm 1620.
• the lost motion piston 1802 will retract into and bottom out in the bore 1804 under the influence of the bias applied to the rocker arm 1620 by the outer plunger spring 1709 via the outer plunger 1708, and remain bottomed out in the bore 1804 when valve actuation motions are applied to the lost motion piston 1802.
• the pre-rocker arm valve train component configured to include the LM- mechanism.
• the pre-rocker arm valve train component may be implemented using other valve train components.
• the LM- mechanism such as the above-described locking mechanism, could be implemented in a cam follower, lifter or similar component.
• the hydraulic fluid required to control the locking mechanism could be provided through suitable passages formed in the pushrod or using other hydraulic fluid provisioning techniques known to those skilled in the art.

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• Valve Device For Special Equipments (AREA)

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• 2022
  • 2022-06-03 CN CN202280035092.XA patent/CN117321291A/zh active Pending
  • 2022-06-03 KR KR1020237039668A patent/KR20230169369A/ko unknown
  • 2022-06-03 JP JP2023573119A patent/JP2024520493A/ja active Pending
  • 2022-06-03 EP EP22815484.5A patent/EP4348013A1/de active Pending
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