Valve operating system with hydraulic lash adjusters that operate via a one-way coupling mechanism

Abstract

The valve actuation system comprises a first rocker assembly operably connected to a first valve actuation motion source and a first engine valve, with a first lost-motion component arranged in series between a first input rocker and a first output rocker. A second rocker assembly is operably connected to a second valve actuation motion source and a second engine valve, with a second lost-motion component arranged in series between a second input rocker and a second output rocker. A one-way coupling mechanism is configured to transmit the second valve actuation motion to the first output rocker, but to prevent the first valve actuation motion from being transmitted to the second output rocker. Furthermore, a primary hydraulic lash adjuster is configured within the second rocker assembly to act on the first output rocker via the one-way coupling mechanism.

Description

Technical Field

[0001] This disclosure generally relates to systems for operating engine valves of internal combustion engines, and more particularly to valve operating systems comprising a hydraulic lash adjuster operating via a one-way coupling mechanism.

Background Art

[0002] The co-pending U.S. patent application Ser. No. 18 / 540,611, filed Dec. 14, 2023 (the “‘611 application”), the teachings of which are incorporated herein by reference, discloses an embodiment of a valve operating system as schematically shown in FIG. 1. In particular, the valve operating system 100 includes a first rocker assembly 110 and a second rocker assembly 140. As shown, the first rocker assembly 110 is operatively connected to a first valve operating motion source 120, and the second rocker assembly 140 is operatively connected to a second valve operating motion source 150. First engine valve 162 and second engine valve 164 (both of which may be, for example, intake valves or exhaust valves) are associated with a cylinder 160 of an internal combustion engine, and valves 162, 164 are operatively connected to one of each of the first rocker assembly 110 and the second rocker assembly 140. In this way, the first rocker assembly 110 and the second rocker assembly 140 operate to operate (i.e., open and close) the engine valves 162, 164 as commanded by the first valve operating motion source 120 and the second valve operating motion source 150 (and in response to the operation of incorporated lost motion components), as will be described in more detail below. Although only a single cylinder 160 is illustrated in FIG. 1, it is understood that an internal combustion engine may include two or more cylinders, and the valve operating systems described herein are applicable to any number of cylinders of a given internal combustion engine.

[0003] The valve actuation motion sources 120, 150 may comprise any combination of known elements capable of providing valve actuation motion, such as cams. Each of the valve actuation motion sources 120, 150 may be dedicated to providing main exhaust motion, main intake motion, auxiliary motion, or a combination of main exhaust or main intake motion together with auxiliary motion. For example, in one embodiment, the first motion source 120 is configured to provide auxiliary valve actuation motion, and the second motion source 150 is configured to provide main valve actuation motion (either exhaust or intake).

[0004] In this embodiment, the first rocker assembly 110 comprises a first input rocker 112, a first lost-motion component 114, and a first output rocker 116 arranged in series. In particular, the first input rocker 112 is operably connected to a first valve actuation motion source 120, the first output rocker 116 is operably connected to a first engine valve 162, and the first lost-motion component 114 is operably connected and positioned between the first input rocker 112 and the first output rocker 116. The first input rocker 112 and the first output rocker 116 may comprise a central pivot (and possibly shaft-mounted) rocker arm, but it is understood that the teachings of this disclosure may also apply equally to end-pivot rocker arms. Optionally, the '611 application discloses that a first hydraulic lash adjuster (HLA) 118 may be included in the first rocker assembly 110. In the illustrated example, the first HLA118 taught by the '611 application is located within a first output rocker 116, which may include a hydraulic passage (not shown) suitable for supplying hydraulic fluid to the first HLA118. The '611 application further teaches that the first HLA118 may instead be located as part of other components 112, 114 constituting the first rocker assembly 110. In addition, the '611 application teaches that when the first HLA118 is provided, it may be desirable to control the operation of the first HLA118, for example, by limiting its stroke, so as not to allow the HLA118 to absorb all the rush in the first rocker assembly 110 (which could result in overextension of the first engine valve 162 when the first lost motion component 114 is operated again in the locked / motion-transmitting state) even when the first lost motion component 114 is in the unlocked / motion-absorbing state.Alternatively, the '944 application teaches that the prevention of engine valve overextension by the operation of the HLA118 may instead be provided by a stroke limit incorporated in the first lost motion component 114 and a biasing force supplied by the first lost motion component 114 that is sufficient to prevent overextension of the HLA118.

[0005] As further illustrated in Figure 1, an engine controller 180 may be provided and operably connected to the first lost motion component 114. The engine controller 180 may include any electronic, mechanical, hydraulic, electrohydraulic, or other type of control device for controlling the operation of the lost motion mechanism 114, i.e., for switching between the respective locked and unlocked states as described above. For example, the engine controller 180 may be implemented by a microprocessor and corresponding memory that stores executable instructions used to implement the necessary control functions, including those described below, as is known in the art. It is understood that other functionally equivalent embodiments of the engine controller 180, e.g., preferably programmed application-specific integrated circuits (ASICs), etc., may be used equally. Furthermore, the engine controller 180 may include intermediate peripheral devices between the engine controller 180 and the first lost motion component 114, enabling the engine controller 180 to achieve control over the operating state of the lost motion device 114. For example, if the lost motion device 114 is a hydraulic control mechanism (i.e., responding to the absence or application of hydraulic fluid to the input), such peripheral devices may include a suitable solenoid.

[0006] As shown in Figure 1, control of the first lost-motion component 114 by the engine controller 180 is provided directly to the first lost-motion component 114. However, in practice, such control may be provided via a path through at least one of the adjacent input rockers 112 or output rockers 116. For example, in various embodiments described herein, such control is provided through the use of hydraulic fluid supplied through one or more fluid passages formed in the first input rocker 112 or the first output rocker 116, under the control of the engine controller 180. However, as will be understood by those skilled in the art, other types of control schemes may be equally employed for this purpose.

[0007] As further shown in Figure 1, the second rocker assembly 140 comprises a second input rocker 142, a second lost-motion component 144, and a second output rocker 146 arranged in series. In particular, the second input rocker 142 is operably connected to a second valve actuation motion source 150, the second output rocker 146 is operably connected to a second engine valve 162, and the lost-motion component 144 is operably connected and positioned between the second input rocker 142 and the second output rocker 146. The second input rocker 142 and the second output rocker 146 may again comprise a central pivot (and possibly shaft-mounted) rocker arm, but it is again understood that the teachings of this disclosure may apply equally to end-pivot rocker arms. Optionally, the '611 application discloses that a second hydraulic lash adjuster (HLA) 148 may be included in the second rocker assembly 140. In the illustrated example, the second HLA148 taught by the '611 application is located within a second output rocker 146, which may include a hydraulic passage (not shown) suitable for supplying hydraulic fluid to the second HLA148. The '611 application further teaches that the second HLA148 may instead be located as part of other components 142, 144 constituting the second rocker assembly 110. In addition, the '611 application teaches that, as with the first HLA118, if a second lost-motion component 144 is located within the second rocker assembly 140, it may be desirable to control the operation of the second HLA148 to prevent overextension of the second engine valve 164. Alternatively, the '611 application again teaches that the prevention of engine valve overextension by the operation of the HLA148 may instead be provided by a stroke limit incorporated in the second lost motion component 144 and a biasing force sufficient to prevent overextension of the HLA148, supplied by the first lost motion component 114.

[0008] The controller 180 is configured to be operably coupled to the second lost-motion component 144, thereby controlling the operation of the second lost-motion component 144. In this case, too, the controller 180 is shown as directly controlling the second lost-motion component 144, but it will be understood that such control may be mediated through paths provided to adjacent components, for example, the second input rocker 142 and / or the second output rocker 146.

[0009] A feature of the illustrated embodiment is the provision of a one-way coupling (OWC) 170 between the second output rocker 146 of the second rocker assembly 140 and the first output rocker 116 of the first rocker assembly 110. The second output rocker 146 can drive the first output rocker 116, but not the other way around, as indicated by the one-way arrow shown in Figure 1 between the second rocker 146, the one-way coupling 170, and the first output rocker 116. That is, the presence of the one-way coupling 170 allows the valve actuation provided by the second valve actuation motion source 150 to be applied to the first output rocker 116, but the valve actuation provided by the first valve actuation motion source 120 cannot be applied to the second output rocker 146. In one embodiment, the one-way coupling 170 is implemented using fixed elements such that the one-way coupling 170 is "always there," i.e., the one-way coupling 170 is not selectable.

[0010] In an alternative embodiment taught in Figure 1 of the '611 application, but not shown herein, the first rocker assembly 110 is as described above, but the second rocker assembly 140 may include a single second rocker configured to directly receive valve actuation motion from the second motion source 150. That is, in this embodiment, the second rocker assembly 140 includes only the second output rocker 146 and not the second input rocker 142 or the second lost motion component 144.

[0011] Nevertheless, when configured as shown in Figure 1, the valve actuation system 100 offers various options for acting the engine valves 162 and 164. For example, if a second valve actuation motion source 150 provides the main valve actuation motion and a first valve actuation motion source 120 provides the auxiliary valve actuation motion, the first lost motion component 114 can be controlled to be in an unlocked or motion-absorbing state so that the auxiliary valve actuation motion applied to the first input rocker 112 is not transmitted by the first lost motion component 114 to the first output rocker 116, or consequently to the first engine valve 162. In addition, the second lost motion component 144 can also be controlled to be in an unlocked or motion-absorbing state so that the main valve actuation motion applied to the second input rocker 142 is not transmitted by the second lost motion component 144 to the second output rocker 146, or consequently to the second engine valve 164 (or to the first engine valve via the one-way coupling 170). Such control of engine valves 162, 164 may be used, for example, to implement cylinder deactivation (CDA) operation of cylinder 160 or engine.

[0012] Alternatively, based on this same example, if the first lost-motion component 114 operates again in its unlocked / motion-absorbing state and the second lost-motion component 144 operates in its locked / motion-transmitting state, the auxiliary valve actuation motion is not transmitted to the first engine valve 162, but the main valve actuation motion is transmitted to both the first valve 162 and the second valve 164. Such control of the engine valves 162, 164 can be used, for example, to implement the positive power generation operation of the engine.

[0013] In another alternative configuration, based on this same example, if the first lost-motion component 114 operates in its locked / motion-transmitting state and the second lost-motion component 144 operates in its locked / motion-transmitting state, the auxiliary valve actuation motion is transmitted to the first engine valve 162 and the main valve actuation motion is transmitted to both the first valve 162 and the second valve 164. Such control of the engine valves 162, 164 can be used, for example, to implement the conventional four-stroke compression-release engine braking action of the engine, or to provide other additional auxiliary valve actuation motions (e.g., internal exhaust gas recirculation (IEGR), variable valve actuation (VVA), early exhaust valve opening (EEVO), late intake valve closing (LIVC), swirl control, etc.).

[0014] In yet another alternative configuration, based on this same example, if the first lost-motion component 114 operates in its locked / motion-transmitting state and the second lost-motion component 144 operates in its unlocked / motion-absorbing state, the auxiliary valve actuation motion is transmitted to the first engine valve 162, but the main valve actuation motion is not transmitted to either the first valve 162 or the second valve 164. Such control of the engine valves 162, 164 can be used to implement operating modes in which auxiliary valve actuation rather than main valve actuation is desired. For example, such operating modes may include so-called two-stroke or 1.5-stroke compression-release engine braking operation of the engine.

[0015] The '611 application further teaches specific implementations of the first lost motion component 114 and the second lost motion component 144. Figure 2 shows an example of such an implementation of the lost motion component 200 taught in the '611 application. The lost motion component 200 is shown in a cross-sectional view, thereby better illustrating the hydraulically controlled locking mechanism 210 which constitutes a subassembly of the lost motion component 200 and is located between the housing 220 and the plunger 222. The housing 220 may be formed as a single element, but in the example shown in Figure 2, the closed end of the housing 220 is provided by an end cap 221 attached to the housing 220. The plunger spring 224 is located outside the housing 220 and the plunger 222. In the illustrated embodiment, the plunger spring 224 is located between a flange 226 formed on or attached to the outer surface of the plunger 222 and a shoulder portion 228 formed inside the housing 220. In this way, the plunger spring 224 biases the housing 220 and the plunger 222 away from each other. It is understood that the plunger spring 224 may be located elsewhere between the housing 220 and the plunger 222, for example, within the housing 220.

[0016] As shown in Figure 2, the locking mechanism 210 includes a plunger 222 slidably disposed within a housing bore 230 that extends from a first end of the housing 220 along the longitudinal axis of the lost motion component 200, preferably concentrically formed therewith. An inner plunger 232 is slidably disposed within a longitudinal bore 234 formed within the plunger 222. An inner plunger spring 242 is provided between the inner plunger 242 and the plunger cap 245, thereby creating a tendency to bias the inner plunger out of the bore 234. A locking element in the form of a wedge 236 is provided, which is configured to engage with an annular outer recess 238 formed on a surface defining the housing bore 230.

[0017] The illustrated embodiment is of a locking mechanism 210 that is normally unlocked, i.e., in this case, without hydraulic control applied to the inner plunger 232 via the lost motion hydraulic passage 240, the inner plunger spring 242 biases the inner plunger 232 to a predetermined position such that the wedge 236 retracts radially through an opening formed in the plunger 220. As a result, the wedge 236 is disengaged from the outer recess 238, thereby effectively unlocking the plunger 222 relative to the housing 220, i.e., consequently, the plunger 222 slides freely within the housing 220, biased in this case by the plunger spring 224. In this unlocked state, any valve operating motion applied to the lost motion component 200 causes the plunger 222 to reciprocate within its bore 230. Thus, assuming that the movement of the plunger 222 within the bore 230 is greater than the maximum range of any applied valve actuation motion (i.e., the plunger 222 cannot reach the bottom within the bore 230), such valve actuation motion is not transmitted by the lost motion component 200 and is effectively lost. Alternatively, the movement of the plunger 222 within the bore 230 may be configured such that the plunger 222 "reaches the bottom," i.e., contacts the closed end of the bore 230, so as to always provide a "fail-safe" valve lift in the event of a locking mechanism 210 failure.

[0018] On the other hand, the supply of hydraulic fluid via the lost motion hydraulic passage 240 to the input receiving end (lowest surface in Figure 3A) of the inner plunger 232, which is sufficiently pressurized to overcome the biasing force of the inner piston spring 242, causes the inner plunger 232 to translate upward (as shown) within the bore 234, thereby forcing the wedge 236 to extend radially through an opening formed in the plunger 222 and engage with the outer recess 238, thereby effectively locking the plunger 222 against the housing 220. In this locked state, valve actuation motion (main motion or auxiliary motion) applied to the lost motion component 200 engages the plunger 222 with the housing 220, thereby transmitting such valve actuation motion.

[0019] It should be noted that when the locking mechanism 210 is in the locked state, the longitudinal extent of the outer recess 238 is greater than the thickness of the wedge 236, allowing for a small amount of movement between the plunger 222 and the housing 220. Such additional space provided by the outer recess 238 facilitates the locking / unlocking of the locking mechanism 210 when the lost motion component 200 is unloaded.

[0020] The bias applied by the plunger spring 224 may be selected to further ensure that adjacent valve train components 252, 254 (e.g., rocker arms as described below, or any additional upstream or downstream valve train components in the system (not shown)) are biased to make continuous contact with the respective endpoints of the valve train, i.e., the valve actuation source and the engine valve.

[0021] Figure 2 shows a specific embodiment and configuration of the lost motion component 200, but other configurations can be used in a similar manner, and the disclosure is not limited in this respect. For example, as stated above, the illustrated lost motion component 200 is a lost motion component that is normally unlocked. However, as will be understood by those skilled in the art, a lost motion component of a normally locked type can be used in a similar manner.

[0022] Referring again to Figure 1, while valve actuation motion (e.g., main valve event) from the second valve actuation motion source 150 is transmitted to the first output rocker 116 by the one-way coupling 170, if the first lost motion component 114, such as the lost motion component 200 shown in Figure 2, is in an unlocked state, the action of the plunger spring 224 causes the housing 220 and plunger 222 to slide away from each other. That is, when the first output rocker 116 is biased toward the first engine valve 162 in accordance with the command of the one-way coupling mechanism 170, the plunger spring 224 biases the plunger 222 and the first input rocker 112 toward the first motion source 120, and the housing 220 toward the first output rocker 116. Referring to Figure 2, the separation of the housing 220 and the plunger 222 results in an increase in the so-called “ball-to-ball” distance D (refer to the hemispherical ball joints 244, 243 used to maintain the lost motion component 200 in a predetermined position between adjacent valve train components 252, 254, while still allowing the rotational motion of the lost motion component 200 relative to adjacent valve train components 252, 254). However, if the ball-to-ball distance D is not kept below its maximum value, the wedge 238 may extend beyond the bore 230 of the housing 220 and thereby detach, or even the plunger 222 may detach from the housing 220.

[0023] To prevent such a situation, it has been proposed to implement a “carry-along” feature between a first output rocker 116 and a first input rocker 112, schematically shown by reference numeral 190 in Figure 1 (e.g., U.S. Patent Application No. 18 / 484,053, filed October 10, 2023). The carry-along feature 190 is designed so that the rotation of the first output rocker 116, caused by a one-way coupling mechanism 170, engages with the first input rocker 112, and induces rotation in the input rocker 112 in accordance with the commands of the first output rocker 116 (which is again commanded by the one-way coupling mechanism 170). The carry-along feature 190 (such as the respective contact surfaces on the first input rocker 112 and the first output rocker 116 which are aligned with each other) is also designed so that rotation of the input rocker 112 is induced before the ball-to-ball distance D of the lost motion components 114, 200 exceeds its maximum value, thereby preventing the aforementioned problem.

[0024] While the carry-along feature 190 can successfully ensure that the ball-to-ball distance D of the first lost-motion components 114, 200 does not exceed a desired maximum value, it may cause other difficulties under certain conditions. For example, the valve actuation system of Figure 1 may be used to actuate an exhaust valve during so-called high power density (HPD) compression-release engine braking. Specifically, as shown in Figure 3, the first valve actuation motion source 120 may provide an auxiliary exhaust valve actuation motion 302 (shown in thin lines) used to achieve 1.5-stroke or 2.0-stroke HPD engine braking (including a first compression-release event 306, a first brake gas recirculation (BGR) event 308, a second compression-release vent 310, and a second BGR event 312), while the second valve actuation motion source 150 may provide a primary exhaust event 304. As is known in the art, during 1.5-stroke HPD engine braking, the intake main event 305 is provided, and at the same time, the exhaust main event 304 is lost and replaced by the auxiliary exhaust valve actuation motion 302. However, during 2.0-stroke HPD engine braking, both the exhaust main event 304 and the intake main event 305 are lost and replaced by the auxiliary exhaust valve actuation motion 302 and the auxiliary intake valve actuation motion (not shown in Figure 3), respectively.

[0025] In this configuration, assuming the implementation of the carry-along feature 190, when the first lost-motion component 114 is in its unlocked state and the second lost-motion component 144 is in its locked state, the rotation of the first output rocker 116 by the one-way coupling mechanism 170 similarly causes the first input rocker 112 to rotate in accordance with the main exhaust event 304 provided by the second motion source 150 to the carry-along feature 190. As a result, the first input rocker 112 loses contact with the first motion source 120 at approximately point 314, i.e., at a crank angle of about 180° as shown in Figure 3, where the lift provided to the first output rocker 116 by the main exhaust event 304 exceeds the lift provided to the first input rocker 112 by the first BGR event 308. However, during the closing of the main exhaust event 304, and during the period T in which the main exhaust event 304 and the second compression release event 310 overlap, the first input rocker 112 moves toward the first motion source 120 (i.e., the cam) at a relatively high speed, while the cam lobe providing the second compression release event 310 moves toward the first input rocker 112. As a result, the first input rocker 112 (more specifically, the cam follower positioned above it) experiences a significant collision with the first motion source 120 at approximately point 316, i.e., at a crank angle of about 350° as shown in Figure 3, where the lift provided to the first input rocker 112 by the first BGR event 308 exceeds the lift provided to the first output rocker 116 by the main exhaust event 304. Such a high-speed collision can lead to damage to the valve train.

[0026] A valve actuation system that overcomes the above limitations while still providing a variety of valve actuation functionalities and flexibility (particularly HPD engine brake operation) with lost motion components would represent a welcome advance in this field. [Overview of the Initiative]

[0027] This disclosure describes various embodiments of a valve actuation system for acting on at least two engine valves in an internal combustion engine. In one embodiment, such a system comprises a first valve actuation motion source and a first rocker assembly operably connected to a first engine valve of at least two engine valves. The first rocker assembly comprises a first input rocker and a first output rocker, and a first lost-motion component arranged in series with the input rocker, the input rocker configured to receive first valve actuation motion from the first valve actuation motion source, and the first output rocker configured to impart first valve actuation motion to the first engine valve. The first lost-motion component is operable to prevent the transmission of first valve actuation motion from the first input rocker to the first output rocker in a motion absorption state, and to transmit first valve actuation motion from the first input rocker to the first output rocker in a motion transmission state. A second rocker assembly is operably connected to a second valve actuation motion source and a second engine valve of at least two engine valves. The second rocker assembly comprises a second input rocker and a second output rocker, and a second lost-motion component arranged in series with the second input rocker, the second input rocker configured to receive second valve actuation motion from a second valve actuation motion source, and the second output rocker configured to impart second valve actuation motion to a second engine valve. The second lost-motion component is operable to prevent the transmission of second valve actuation motion from the second input rocker to the second output rocker in a motion absorption state, and to transmit second valve actuation motion from the second input rocker to the second output rocker in a motion transmission state. A one-way coupling mechanism is positioned between the first output rocker and at least one second rocker such that second valve actuation motion is transmitted from at least one second rocker to the first output rocker, and first valve actuation motion is not transmitted from the first output rocker to at least one second rocker.Furthermore, a primary hydraulic lash adjuster is configured within the second rocker assembly such that it acts on the first output rocker via a one-way coupling mechanism. In one embodiment, the primary hydraulic lash adjuster may be disposed within the second output rocker.

[0028] In another embodiment, each of the first input rocker, the first output rocker, the second input rocker, and the second output rocker includes a half rocker attached to a shaft.

[0029] In another embodiment, the one-way coupling mechanism includes a second extension forming part of at least one second output rocker and a first extension forming part of the first output rocker, and the first extension and the second extension are configured to contact each other.

[0030] In another embodiment, the first lost motion component includes a hydraulically controlled locking mechanism. Further, the first lost motion component may include a first spring that biases the first input rocker toward the first valve actuating motion source and biases the first output rocker toward the first engine valve. Additionally, the first lost motion component may have a longitudinal range sufficient to accommodate the motion applied to the first output rocker via the one-way coupling mechanism. The first lost motion component may also be configured such that its stroke is limited.

[0031] In another embodiment, the system may include a secondary hydraulic lash adjuster disposed between the second output rocker and the second engine valve. In this case, the secondary lash preventing force provided by the secondary hydraulic lash adjuster is preferably less than the primary lash preventing force provided by the primary hydraulic lash adjuster.

[0032] In one embodiment, the second lost motion component includes a hydraulically controlled locking mechanism. Furthermore, the second lost motion component may include a second spring that biases the first input rocker toward the second valve actuation motion source and the second output rocker toward the second engine valve. Moreover, the second lost motion component may be configured to limit the stroke.

[0033] In yet another embodiment, the system includes a first valve actuation motion source and a first rocker assembly operably connected to a first engine valve among at least two engine valves. The first rocker assembly comprises a first input rocker and a first output rocker, and a first lost-motion component arranged in series with the first input rocker, which is configured to receive first valve actuation motion from the first valve actuation motion source, and the first output rocker, which is configured to impart first valve actuation motion to the first engine valve. The first lost-motion component is operable to prevent the transmission of first valve actuation motion from the first input rocker to the first output rocker in a motion absorption state, and to transmit first valve actuation motion from the first input rocker to the first output rocker in a motion transmission state. A second rocker assembly is operably connected to a second valve actuation motion source and a second engine valve among at least two engine valves. The second rocker assembly comprises at least one second rocker configured to receive a second valve actuation motion from a second valve actuation motion source and impart the second valve actuation motion to a second engine valve. A one-way coupling mechanism is positioned between the first output rocker and at least one second rocker such that the second valve actuation motion is transmitted from at least one second rocker to the first output rocker, and the first valve actuation motion is not transmitted from the first output rocker to at least one second rocker. In this embodiment, the first rocker assembly comprises a hydraulic lash adjuster, and the first valve actuation motion source includes a replenishment period including a subbase circle lift configured to relieve the load on the hydraulic lash adjuster by extending a first lost motion component. [Brief explanation of the drawing]

[0034] The aforementioned and other features and advantages will be discussed in detail in the following non-limiting description of specific embodiments, along with the accompanying drawings. [Figure 1]This is a schematic diagram of an embodiment of a valve actuation system including a lost motion component, from which the teachings of this disclosure can be beneficial. [Figure 2] This is a cross-sectional view of an example of a lost motion component that may be used to implement the system shown in Figure 1. [Figure 3] This graph shows the main valve events and auxiliary valve events used in conjunction with HPD engine braking. [Figure 4] This is a cross-sectional view of an alternative example of a lost-motion component that may be used to implement the system of Figure 1 without requiring a carry-along feature. [Figure 5] This is a schematic diagram of an embodiment of a valve actuation system including a lost motion component as taught in this disclosure. [Figure 6] Figure 5 shows the valve operating system. [Figure 7] Figure 5 shows the valve operating system. [Figure 8] Figure 5 shows the valve operating system. [Figure 9] This is a schematic diagram of an alternative embodiment of a valve actuation system including a lost motion component, as taught in this disclosure. [Figure 10] This is a graph showing the hydraulic lash adjuster replenishment period provided by the first motion source according to the current preferred embodiment. [Modes for carrying out the invention]

[0035] As used herein, the term “operably connected” is understood to mean a functional relationship between at least two components, i.e., the claimed components must be connected to perform the indicated function (potentially including the presence of intervening elements or components).

[0036] The 611 application further describes lost motion components that can be used in place of the carry-along feature 190, thereby avoiding the collision problem of the first input rocker 112 caused by the carry-along feature 190. Figure 4 shows an example of such a lost motion component 200'. Elements having the same reference numerals in Figures 2 and 4 are substantially similar in structure and function, however, reference numerals with a prime symbol (') in Figure 4 refer to elements characterized by different structures and / or functions from their counterparts shown in Figure 2, as will be described below. In the embodiment shown in Figure 4, the lost motion component 200' again includes a housing 220 in which a longitudinal bore 230 is formed, and a plunger 222 slidably disposed within the bore 230. Similarly, the inner plunger 232 is located within a bore 234 formed in the plunger 222 and is biased out of the bore 234 by an inner plunger spring 242 located between the inner plunger 232 and a plunger cap 245.

[0037] Again, the inner plunger 232 is structured to provide an operation that is normally unlocked, i.e., in the absence of hydraulic control applied to the inner plunger 232, the inner plunger spring 242 biases the inner plunger 232 into place so that the wedge 236 does not extend radially from the opening formed in the plunger 232 and therefore does not engage with the outer annular recess 238', thereby effectively unlocking the plunger 222 against the housing 220, allowing the plunger 222 to slide freely within its bore 230 under the bias provided by the plunger spring 224.

[0038] On the other hand, the supply of hydraulic fluid to the input receiving end (lowest surface shown in Figure 4) of the inner plunger 232, which is sufficiently pressurized to overcome the biasing force of the inner piston spring 242, causes the inner plunger 232 to translate within the bore 234, forcing the wedge 236 to extend and engage with the outer recess 238', as shown in Figure 4, thereby effectively locking the plunger 222 against the housing 220.

[0039] A further feature of the housing 220 is that the annular outer recess 238' has a larger longitudinal range than the annular outer recess 238 shown in Figure 2. Thus, when the plunger 222 is unlocked from the housing 220 and the first output rocker 116 is commanded by the one-way coupling mechanism 170 as described above, the larger range of the annular outer recess 238' allows for a larger maximum ball-to-ball distance D' without the risk of the wedge 236 or plunger 222 falling out. In addition, given this larger maximum ball-to-ball distance D', the housing 220 and plunger 222 can be biased further apart by the plunger spring 224 so that the first input rocker 112 is biased to be in continuous contact with the first motion source 120. As a result, the first input rocker 112 can remain in contact with the first motion source 120, thus avoiding the aforementioned collision between the first input rocker 112 and the first motion source 120.

[0040] An additional feature of the lost motion component 200' shown in Figure 4 is the provision of a stroke limiting feature to prevent overextension of the plunger 222 from the housing 220. In the illustrated example, this stroke limiting feature comprises a shoulder 402 formed in the wall defining the housing bore 230 and a corresponding flange or lip 404 formed at the end of the plunger 222 that overlaps with the shoulder 402. In one embodiment, the flange 404 is configured to engage with the shoulder 402 when the plunger 222 moves outward (away from) the housing 220, thereby preventing the plunger 222 from extending beyond a maximum distance from the housing 220 in all cases.

[0041] As described above with respect to Figure 1, HLA118, 148 may optionally be included in the first and second rocker assemblies 110, 140. However, as described above, the type of lost motion component 200' shown in Figure 4 allows the plunger spring 224 to always apply force to both the housing 220 and the plunger 222, and therefore to the first input rocker 112 and the first output rocker 116 as well. If the HLA118 is positioned between the first output rocker 116 and the first valve 162 as shown in Figure 1, the constant force applied to the first output rocker 116 by the plunger spring 224 prevents such HLA118 from being crushed and / or expanding for normal operation.

[0042] To accommodate the presence of HLAs (such as HLA118) within the first rocker assembly 110, the first valve actuation motion source 120 may provide a period of negative valve lift so that the HLA is unloaded for at least a certain period during each engine cycle (whether or not the valve actuation motion provided by the first valve actuation motion source 120 is transmitted to the first engine valve 162), thereby allowing the HLA to expand and provide lash-absorbing force to eliminate any lash in the valve train, i.e., the first rocker assembly 110 and the first engine valve 162. An example of this is shown in Figure 10, as in Figure 3, which illustrates the exhaust main event 1004 and the intake main event 1005, and in this example, the auxiliary exhaust valve actuation motion 1002 that can be provided by the first motion source 120. (Note that in this example, all illustrated engine valve events are phase-shifted by 65° compared to the engine valve events shown in Figure 3.) However, in this case, the auxiliary exhaust valve actuation motion 1002 includes an HLA replenishment period 1007 of crank angles from approximately 500° to approximately 560°, during which a constant lift of approximately -7 mm is provided to the subbase circle (i.e., below the 0 mm lift axis shown in Figure 10). The amount of negative lift provided during the HLA replenishment period 1007 is determined by the maximum extension of the first lost motion assembly 114. That is, the HLA replenishment period 1007 allows the plunger spring 224 to bias the housing 220 and the plunger 222 (as used to implement the first lost motion component 114) to move as far apart as possible, i.e., to the extent permitted by the movement limiting features 402, 404 within the first lost motion component 114. In this state, the first lotion motion assembly 114 cannot expand further and therefore does not load the HLA in the first rocker assembly 110. Subsequently, the HLA expands freely and absorbs the lash in the first rocker assembly 110 that would have been absorbed by the plunger spring 224 if it had been possible to expand further.

[0043] In another embodiment, a system 500, as shown in Figure 5, may be used to provide the benefits of an HLA while avoiding the aforementioned problems arising from the presence of an HLA in the first rocker assembly 110. As shown, system 500 is substantially identical to system 100 in Figure 1, except that the HLA 148 located between the second output rocker 146 and the second valve 164 in Figure 1 is removed and replaced with a first HLA or primary HLA 502 located between the second lost motion component 144 and the second output rocker 146. With this configuration, the first HLA 502 can operate in a similar manner to the HLA 148 in Figure 1 to absorb lash in the valve train established by the second motion source 150, the second rocker assembly 140, and the second valve 164. Furthermore, the first lash adjuster 502 can act on the first output rocker 116 via a one-way coupling 170, thereby minimizing lash between the first output rocker 116 and the first engine valve 162. However, because of the presence of the unidirectional coupling 170, the constant bias applied by the plunger spring 224 (as part of the first lost motion component 114) cannot be applied to the first HLA 502, thereby preventing any interference with the operation of the first HLA 502. In other words, the configuration of the first HLA 502 within the second rocker assembly 140 allows the first HLA 502 to operably communicate with the first output rocker 116 via the unidirectional coupling 170, thereby acting on both the first output rocker 116 and the second rocker assembly 140. Although the first HLA 502 is shown as being located within the second output rocker 146, it should be noted that the first HLA 502 may be located elsewhere within the second rocker assembly 140, provided that it is still possible for it to act on the first output rocker 116 via the unidirectional coupling 170 (i.e., to apply a rush-absorbing force).

[0044] Figures 6 to 8 show a specific implementation of system 600 according to Figure 5. System 600 comprises a first rocker assembly 610 and a second rocker assembly 640 configured to actuate first and second engine valves 662 and 664, respectively. The first rocker assembly 610 comprises a first input rocker 612 operably connected to a first lost-motion component 614, which in turn operably connects to a first output rocker 616. Similarly, the second rocker assembly 640 comprises a second input rocker 642 operably connected to a second lost-motion component 644, which in turn operably connects to a second output rocker 646. As shown, all rockers 612, 616, 642, and 646 are half-shaft mounted rockers, but this is not a requirement. As further shown, a one-way coupling 670 is positioned between the second output rocker 646 and the first output rocker 616. In this configuration, the one-way coupling 670 is configured to be non-selectable, i.e., "always there," and is integrally formed within the second and first output rockers 646, 616, respectively, and includes overlapping extensions 672, 674 that extend away from each of them. When configured as shown, a valve actuation motion applied to the second output rocker 646 causes the first extension 672 to contact the second extension 674, thereby acting the first output rocker 616 as well. On the other hand, a valve actuation motion applied to the first output rocker 616 does not result in contact between the second extension 674 and the first extension 672. As further shown in Figure 6, the first output rocker 616 and the second output rocker 646 each include a swivel or e-foot 666, 668 positioned at their motion-giving ends and configured to contact the respective first and second engine valves 662, 664.

[0045] Figure 7 shows a cross-sectional view of the first rocker assembly 610, which generally comprises a first input rocker 612 operably connected to a first lost-motion component 614, 200', the first lost-motion component 614, 200', which is operably connected to a first output rocker 616. The first input rocker 612 comprises a first roller follower 702 configured to contact a first valve actuation motion source, i.e., a cam (not shown). In this configuration, valve actuation motion applied to the first roller follower 702 is transmitted by the first input rocker 612 to the first lost-motion component 614, 200'. Depending on the locked / unlocked state of the first lost-motion component 614, 200', valve actuation motion applied to the first input rocker 612 may be transmitted / absorbed (lost) by the first lost-motion component 614, 200'. When transmitted by the first lost motion component 614, 200', the valve actuation motion is also applied to the first output rocker 616 and the first engine valve (not shown).

[0046] In this implementation, the connection between the first input rocker 612 and the first lost motion component 614, 200' is provided by a lash adjustment screw 704 terminated by a hemispherical ball joint 244 at the end adjacent to the first lost motion component 614, 200'. Using known techniques, a lash adjustment screw 407 may be used to set the lash in a valve train comprising the first rocker assembly 601, which can be maintained by a lock nut 706. Furthermore, as indicated by reference numerals, the first lost motion component 614, 200' includes features of the lost motion component 200' described with reference to Figure 4, such that the first input rocker 612 and the first output rocker 616 are biased away from each other, while maintaining the first input rocker 612 in contact with a first valve actuation motion source (not shown) and the first output rocker 616 in contact with a first engine valve (not shown) via a swivel 666.

[0047] Note that the embodiment shown in Figure 7 includes stroke-limiting features of the overlapping shoulder portion 402 and flange 404, thereby ensuring that overextension of the plunger 222 relative to the housing 220 does not occur.

[0048] Figure 8 shows a cross-sectional view of the second rocker assembly 640, which generally comprises a second input rocker 642 operably connected to a second lost-motion component 644, 200, the second lost-motion component 644, 200 operably connected to a second output rocker 646. The second input rocker 642 comprises a second roller follower 802 configured to contact a second valve actuation motion source, i.e., a cam (not shown). In this case, as indicated by the reference numerals, the second lost-motion component 644, 200 includes the features of the lost-motion component 200 described with reference to Figure 2, such that the second input rocker 642 and the second output rocker 646 are biased toward each other. With this configuration, the valve actuation motion applied to the second roller follower 802 is transmitted to the second lost-motion component 644, 200 by the second input rocker 642. Depending on the locked / unlocked state of the second lost-motion components 644, 200, the valve actuation motion applied to the second input rocker 642 may be transmitted / absorbed (lost) by the first lost-motion components 644, 200. Once transmitted by the second lost-motion components 644, 200, the valve actuation motion is also applied to the second output rocker 646 and the first engine valve (not shown).

[0049] The control of lash adjustment in the second rocker assembly 640 according to the embodiment of Figure 5 is handled differently from that of the first rocker assembly 610. For example, instead of the lash adjustment screw 704 shown in Figure 7, the connection between the second input rocker 642 and the second lost motion components 644, 200 is provided in this case by a plug 804 that provides a concave surface 806 configured to complementarily receive a hemispherical ball joint provided on the end cap of the second lost motion components 644, 200. Alternatively, lash adjustment in the second rocker assembly 640 is provided by a first HLA 502 operably connected to both the second lost motion component 644 and the second output rocker 646, as shown (and according to the embodiment of Figure 5). According to known art, the first HLA 502 comprises an HLA housing 808 configured to be screw-received into an HLA bore 810 formed in the nose of the second output rocker 646. The HLA insert 812 is slidably received within the HLA chamber 814, which is formed by the bore of the HLA housing 808 and the end face of the HLA bore 810. The HLA insert 812 forms an orifice 816, which is closed by a check disc 818 and a check spring 820, which are located within a high-pressure chamber 822 formed by the space between the HLA housing 808 and the HLA insert 812. As is known in the art, the check disc 818 may also be implemented as a check ball.

[0050] As is known in the art, when no valve operating load is applied to the second rocker assembly 640, the pressurized hydraulic fluid supplied to the HLA chamber 814 (supplied from a pressurized hydraulic fluid source via a suitable hydraulic passage formed in the second output rocker 646, neither of which are shown) can overcome the bias applied to the check disc 818 by the check spring 820, thereby causing the hydraulic fluid to flow from the HLA chamber 814 into the high-pressure chamber 822. As is further known in the art, the biasing force resulting from such hydraulic fluid flow causes the HLA housing 808 and the HLA insert 812 to move away from each other, thereby absorbing (i.e., substantially reducing or eliminating) the lash present in the valve train comprising the second rocker assembly 640. Furthermore, as described with reference to Figure 5, the biasing force applied by the first HLA 502 is also transmitted to the first output rocker arm 616 by the one-way coupling 670, thereby absorbing any additional lash space between the first output rocker arm 616 and the first engine valve 662.

[0051] Although not shown in Figure 8 (due to the rotation of the housing 220 and plunger 222 relative to the cross-section in Figure 8), the stroke-limiting features of the overlapping shoulders 402 and flange 404 are preferably incorporated into the first lost-motion component 644 to prevent further overextension of the plunger 222 relative to the housing 220.

[0052] The systems according to Figures 5 to 8 beneficially enable the use of HLAs to absorb lash in valve actuation systems, but further drawbacks may arise. More specifically, referring again to Figure 5, during a particular valve actuation (e.g., main valve actuation provided by the second motion source 150), the speed at which the first and second engine valves 162, 164 return toward seating (so-called valve retraction speed) may differ. For example, if the first engine valve 162 fully seats before the second engine valve 164 fully seats according to the main valve actuation, any lash adjustment provided by the first HLA 502 is set by the first engine valve 162 (via the one-way coupling 170), which may lead to the formation of a gap between the second output rocker 146 and the second engine valve 164.

[0053] To address this possibility, the system 500 in Figure 5 can be modified as shown in Figure 9. The valve actuation system 900 shown in Figure 9 is identical to the system 500 shown in Figure 5, except that, in addition to the first HLA 502, a second HLA or secondary HLA 902 is provided between the second output rocker 146 and the second engine valve 164. With this configuration, the second HLA 902 can absorb any lash space between the second output rocker 146 and the second engine valve 164 resulting from the different valve retraction speeds and the operation of the first HLA 502 as described above.

[0054] Those skilled in the art will understand that connecting the first and second HLA502,902 in series with each other tends to cause them to act against each other. To prevent any undesirable operating conditions that may arise from collisions between the first HLA502 and the second HLA902, the second HLA902 can be configured to generate a lower lash-preventing bias than that provided by the first HLA502. This can be achieved by configuring the HLA housing and HLA insert of the second HLA902 to have a smaller diameter than the corresponding components in the first HLA502, even though they operate with the same pressurized hydraulic fluid supply. With this configuration, the first HLA502 can be extended to a point determined by the first output rocker 116 / first engine valve 162, which also allows the second HLA902 to be extended to a point determined by any lash formed between the second output rocker 146 and the second engine valve 164.

[0055] As configured as shown in Figure 9, the first and second HLA502,902 are maintained under compressive load under all operating conditions, thereby preventing undesirable "jacking up" (overextension) of the first and second HLA502,902. For example, continuing to refer to Figure 9, when positive power generation operation of the engine is desired, the first lost motion component 114 operates in its unlocked / motion absorption state, and the second lost motion component 144 operates in its locked / motion transmission state, thereby preventing auxiliary valve actuation motion from being transmitted to the first engine valve 162, while main valve actuation motion is transmitted to both the first valve 162 and the second valve 164. In this case, both the first and second HLA502,902 are continuous in the main motion load path (i.e., from the second motion source 150 to the second engine valve 164), and therefore overextension is prevented.

[0056] As another example, if combined valve actuation motion from first and second motion sources 120, 150 is desired (e.g., compression release engine brake, IEGR, VVA, EEVO, LIVC, etc.), the first lost motion component 114 operates in its locked / motion transmission state, and the second lost motion component 144 also operates in its locked / motion transmission state, thereby transmitting auxiliary valve actuation motion to the first engine valve 162 and main valve actuation motion to both the first and second valves 162, 164. In this case, the second motion source 150 does not provide valve actuation motion via the second rocker assembly 140 (e.g., the cam providing the second motion source 150 is located in the base circle), but a gap may occur between the components of the one-way coupling 170 (overlapping extensions 672, 674 in the example of Figure 6) when the first motion source 120 provides valve actuation motion via the first rocker assembly 110. An example of such a state is shown in Figure 3, where, at a crank angle of 0°, the main exhaust valve actuation motion 304 is not provided, but the first compression release valve actuation motion 306 is provided. In this case, despite the separation between the components forming the one-way coupling 170, the first and second HLAs 502, 902 remain under compression, for example, by the plunger spring 224 found in the first lost-motion component 114.

[0057] As yet another example, if auxiliary valve actuation is desired for the engine (e.g., a 1.5-stroke or 2-stroke compression-release engine brake), the first lost-motion component 114 operates in its locked / motion-transmitting state, and the second lost-motion component 144 operates in its unlocked / motion-absorbing state, thereby transmitting the auxiliary valve actuation motion to the first engine valve 162, but not the main valve actuation motion to either the first valve 162 or the second valve 164. In this case, the valve actuation motion from the second motion source 150 is not transmitted through the second rocker assembly 140, i.e., the main valve actuation motion does not compress either the first HLA 502 or the second HLA 902. However, even in this case, the first and second HLA 502 and 902 remain under compression by the plunger spring 224 located within the first lost-motion component 114.

Claims

1. A system for acting at least two engine valves associated with a cylinder of an internal combustion engine, A first rocker assembly operably connected to a first valve actuation motion source and a first engine valve among the at least two engine valves, comprising a first lost-motion component arranged in series with a first input rocker and a first output rocker, wherein the first input rocker is configured to receive first valve actuation motion from the first valve actuation motion source, and the first output rocker is configured to impart the first valve actuation motion to the first engine valve, and the first lost-motion component is operable to prevent the transmission of the first valve actuation motion from the first input rocker to the first output rocker in a motion absorption state, and to transmit the first valve actuation motion from the first input rocker to the first output rocker in a motion transmission state, A second rocker assembly operably connected to a second valve actuation motion source and a second engine valve among the at least two engine valves, comprising a second lost-motion component arranged in series with a second input rocker and a second output rocker, wherein the second input rocker is configured to receive second valve actuation motion from the second valve actuation motion source, and the second output rocker is configured to impart the second valve actuation motion to the second engine valve, and the second lost-motion component is operable to prevent the transmission of the second valve actuation motion from the second input rocker to the second output rocker in a motion absorption state, and to transmit the second valve actuation motion from the second input rocker to the second output rocker in a motion transmission state, The system includes a one-way coupling mechanism positioned between the first and second output rockers such that the second valve actuation motion is transmitted from the second output rocker to the first output rocker, and the first valve actuation motion is not transmitted from the first output rocker to the second output rocker. A system in which a primary hydraulic lash adjuster is configured within the second rocker assembly to act on the first output rocker via the one-way coupling mechanism.

2. The system according to claim 1, wherein the primary hydraulic lash adjuster is located within the second output rocker.

3. The system according to claim 1, wherein each of the first input rocker, the first output rocker, the second input rocker, and the second output rocker includes a half rocker attached to a shaft.

4. The system according to claim 1, wherein the one-way coupling mechanism comprises a second extension that forms part of at least one second output rocker and a first extension that forms part of the first output rocker, and the first extension and the second extension are configured to be in contact with each other.

5. The system according to claim 1, wherein the first lost motion component includes a hydraulically controlled locking mechanism.

6. The system according to claim 1, wherein the first lost motion component includes a first spring that biases the first input rocker toward the first valve actuation motion source and the first output rocker toward the first engine valve.

7. The system according to claim 1, wherein the first lost motion component has a sufficient longitudinal range to correspond to the motion applied to the first output rocker via the unidirectional coupling mechanism.

8. The system according to claim 1, wherein the first lost motion component is configured to limit the stroke.

9. The system according to claim 1, further comprising a secondary hydraulic lash adjuster positioned between the second output rocker and the second engine valve.

10. The system according to claim 9, wherein the secondary lash-preventing force provided by the secondary hydraulic lash adjuster is less than the primary lash-preventing force provided by the primary hydraulic lash adjuster.

11. The system according to claim 1, wherein the second lost motion component includes a hydraulically controlled locking mechanism.

12. The system according to claim 1, wherein the second lost motion component includes a second spring that biases the first input rocker toward the second valve actuation motion source and the second output rocker toward the second engine valve.

13. The system according to claim 1, wherein the second lost motion component is configured to limit the stroke.

14. A system for acting at least two engine valves associated with a cylinder of an internal combustion engine, A first rocker assembly operably connected to a first valve actuation motion source and a first engine valve among the at least two engine valves, comprising a first lost-motion component arranged in series with a first input rocker and a first output rocker, wherein the first input rocker is configured to receive first valve actuation motion from the first valve actuation motion source, and the first output rocker is configured to impart the first valve actuation motion to the first engine valve, and the first lost-motion component is operable to prevent the transmission of the first valve actuation motion from the first input rocker to the first output rocker in a motion absorption state, and to transmit the first valve actuation motion from the first input rocker to the first output rocker in a motion transmission state, A second rocker assembly operably connected to a second valve actuation motion source and a second engine valve among the at least two engine valves, comprising at least one second rocker configured to receive a second valve actuation motion from the second valve actuation motion source and to impart the second valve actuation motion to the second engine valve, The system includes a one-way coupling mechanism positioned between the first output rocker and the at least one second rocker such that the second valve actuation motion is transmitted from the at least one second rocker to the first output rocker, and the first valve actuation motion is not transmitted from the first output rocker to the at least one second rocker, The first rocker assembly comprises a hydraulic lash adjuster, The system includes a replenishment period, which includes a sub-base circle lift configured to remove the load on the hydraulic lash adjuster by expanding the first lost-motion component, wherein the first valve actuation motion source is a first valve actuation motion source.

15. The at least one second locker is The system according to claim 14, comprising a second lost motion component arranged in series with a second input rocker and a second output rocker, wherein the second input rocker is configured to receive the second valve actuation motion from the second valve actuation motion source, the second output rocker is configured to impart the second valve actuation motion to the second engine valve, and the second lost motion component is operable to prevent the transmission of the second valve actuation motion from the second input rocker to the second output rocker in a motion absorption state, and to transmit the second valve actuation motion from the second input rocker to the second output rocker in a motion transmission state.

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