Valve actuation system including discrete lost motion device

Abstract

A valve actuation system includes a first arm having a first arm contact surface and operatively connected to a valve actuation motion. A second arm having a second arm contact surface is operatively connected to at least one engine valve. A discrete lost motion device is provided that is controllable between a first motion transmission state and a second motion absorption state. The discrete lost motion device includes a plunger contact surface and a housing contact surface. The housing contact surface is configured to engage one of the first arm contact surface or the second arm contact surface, and the plunger contact surface is configured to engage the other of the first arm contact surface and the second arm contact surface. The first and second arm contact surfaces, the housing contact surface, and the first plunger contact surface are configured to support the discrete lost motion device between the first and second arms.

Description

Background Art

[0001] Valve actuation in an internal combustion engine is necessary for engine operation. Generally, the valve actuation force for opening an engine valve (i.e., an intake valve, an exhaust valve, or an auxiliary engine valve) is transmitted by a valve train, where such valve actuation force can be provided by a primary motion source and / or an auxiliary motion source. As used herein, the descriptor "primary" refers to the so-called primary event engine valve motion, i.e., the valve motion used during positive power generation, where fuel is burned in an engine cylinder to provide a net output of engine power; however, the descriptor "auxiliary" refers to other engine valve motions used for purposes alternative to positive power generation (e.g., compression release braking, exhaust braking, cylinder deactivation, cylinder cut-off, brake gas recirculation (BGR), etc.) or as a supplement to positive power generation (e.g., internal exhaust gas recirculation (IEGR), variable valve actuation (VVA), early exhaust valve opening (EEVO), late intake valve closing (LIVC), swirl control, etc.).

[0002] In many internal combustion engines, the primary motion source and / or the auxiliary motion source can be provided by a cam with a fixed profile, and more specifically by one or more fixed lobes or projections (which can be an integral part of each cam in the cam). If the intake valve and / or exhaust valve timing and lift can be changed, benefits such as improved performance, better fuel economy, reduced emissions, and better vehicle drivability can be obtained. However, the use of a fixed profile cam may make it difficult to adjust the timing and / or amount of engine valve lift to optimize them for various engine operating conditions.

[0003] Given a fixed cam profile, one method of adjusting valve timing and lift is to provide a "lost motion" or variable length device in the valve train linkage between a given engine valve and its corresponding cam. Lost motion is a term applied to a class of technical solutions for varying the valve actuation motion defined by a cam profile having variable length mechanical, hydraulic, or other linkage components. In a lost motion system, the cam lobe can provide the "maximum" motion (longest dwell and maximum lift) required over the entire range of engine operating conditions, including positive power generating operations and / or auxiliary operations as required in some cases. The variable length system can then be included in the valve train linkage between the valve to be opened and the cam providing the maximum motion to reduce or lose some or all of the motion imparted to the valve by the cam. Typically, such lost motion devices are capable of being controlled between a "locked" or motion transmitting state and an "unlocked" or motion absorbing state. During the locked state, the lost motion device remains in a substantially rigid configuration (allowing clearance adjustment) such that the valve actuation motion applied to it is transmitted to the corresponding engine valve. On the other hand, during the unlocked state, the lost motion device is allowed to absorb or avoid (i.e., "lose") any valve actuation motion applied to it, thereby preventing such valve actuation motion from being transmitted to the corresponding engine valve.

[0004] Figure 1 An embodiment of a conventional valve actuation system 100 including a lost motion component 130 is schematically shown. As shown, the valve actuation system 100 includes a valve actuation motion source 102 that serves as the sole source of valve actuation motion (i.e., valve opening motion and valve closing motion) for one or more engine valves 104 via a valve actuation load path 106. The one or more engine valves 104 are associated with a cylinder 105 of an internal combustion engine. As is known in the art, each cylinder 105 typically has at least one valve actuation motion source 102 uniquely corresponding to it for actuating the corresponding engine valve 104. Additionally, although only a single cylinder 105 is shown Figure 1 in the figure, it should be understood that an internal combustion engine can include and often does include more than one cylinder, and the valve actuation systems described herein are applicable to any number of cylinders of a given internal combustion engine.

[0005] The valve actuation motion source 102 can include any combination of known elements capable of providing valve actuation motion, such as a cam. The valve actuation motion source 110 can be dedicated to providing exhaust motion, intake motion, auxiliary motion, or a combination of exhaust or intake motion and auxiliary motion.

[0006] As shown, a valve actuation load path 106 can include one or more valve train components (in the example shown, a first valve train component 108 and a second valve train component 110), which are deployed between a valve actuation motion source 102 and at least one engine valve 104 and are configured to transfer the motion provided by the valve actuation motion source 102 to the at least one engine valve 104, such as tappets, push rods, rocker arms, valve bridges, automatic clearance adjusters, etc. Although Figure 1 two valve train components 108, 110 are shown, it should be understood that more or fewer valve train components may be used. Further, in this example, the valve actuation load path 106 includes a lost motion component 130 housed within the second valve train component 110. That is, although the lost motion component 130 may contact other components within the valve train 106, since it is housed within the second valve train component 110, the lost motion component is fully supported by the valve train 106 and retained within the valve train. For example, the second valve train component 110 may be implemented by a rocker arm or a valve bridge that has a bore formed therein, and the components forming the lost motion component 130 are deployed within the bore.

[0007] As Figure 1 further shown, an engine controller 120 may be provided and is operably connected to the lost motion component 130. The engine controller 120 may include any electronic, mechanical, hydraulic, electro-hydraulic, or other type of control device for controlling the operation of the lost motion mechanism 130, i.e., switching between its respective locked and unlocked states as described above. For example, the engine controller 120 may be implemented by a microprocessor and a corresponding memory storing executable instructions for implementing the desired control functions, including those described below that are known in the art. It should be understood that other functionally equivalent specific implementations of the engine controller 130 (e.g., a suitably programmed application specific integrated circuit (ASIC), etc.) may be equivalently employed. Further, the engine controller 120 may include peripherals that are intermediate the engine controller 120 and the lost motion device 130, which allow the engine controller 120 to implement control over the operating state of the lost motion device 130. For example, in the case where the lost motion device 130 is a hydraulically controlled mechanism (i.e., responsive to the absence or application of hydraulic fluid to an input), such peripherals may include suitable solenoids known in the art.

[0008] Figure 2 Another embodiment of a conventional valve actuation system 100’ including a lost motion component 230 is schematically shown, where Figure 1In comparison, like reference numerals denote like elements. In this second embodiment, the floating member 230 is not housed within one of the valve mechanism components 108, 110, but rather is housed within a stationary member 232, such as a cylinder head or engine block, while still contacting the second valve mechanism component 110. For example, in the case where the second valve mechanism component 110 is an end pivot type rocker arm or finger follower, the floating member 230 may be implemented by a collapsible pivot known in the art.

[0009] Cost, packaging, and size are often factors that determine the desirability of an engine valve actuation system. Generally, in cases where it is desired to incorporate one or more floating members into a valve mechanism, the ability to include valve mechanism components that house such floating members may be limited by a variety of factors, such as a lack of space due to their large size and / or high cost. Thus, providing a valve actuation system that includes floating members that overcome these limitations would represent a welcome technological advancement. SUMMARY OF THE INVENTION

[0010] The present disclosure describes various embodiments of a valve actuation system for actuating at least one engine valve in an internal combustion engine. In various embodiments, the valve actuation system includes a first arm operatively connected to a valve actuation motion source to receive valve actuation motion from the valve actuation motion source, the first arm further having a first arm contact surface. A second arm is operatively connected to at least one engine valve to apply valve actuation motion to the at least one engine valve, the second arm further having a second arm contact surface. A discrete floating device includes: a housing having a housing contact surface; and a plunger that is controllable between a first state in which the plunger is rigidly held relative to the housing and a second state in which the plunger is permitted to reciprocate relative to the housing, the plunger further including an end having a plunger contact surface. The housing contact surface is configured to engage one of the first arm contact surface or the second arm contact surface, and the plunger contact surface is configured to engage the other of the first arm contact surface and the second arm contact surface. Further, the first arm contact surface, the second arm contact surface, the housing contact surface, and the first plunger contact surface are configured to support the discrete floating device between the first arm and the second arm.

[0011] In one embodiment, the housing includes a housing bore that extends longitudinally into the housing from a first end of the housing, and the plunger is disposed in the housing bore through the first end of the housing. In this embodiment, the second end of the housing or the end of the plunger includes a floating hydraulic passage that is configured to receive hydraulic fluid to control the plunger between the first state and the second state of the plunger. Still further, the first arm or the second arm includes a hydraulic supply passage that is configured to register with the floating hydraulic passage.

[0012] In one embodiment, the first arm contact surface and the second arm contact surface are configured to allow the idle device to rotate relative to the first arm and the second arm. For example, the first arm contact surface may be concave, and at least one of the housing contact surface or the plunger contact surface is convex, or the first arm contact surface may be convex, and at least one of the housing contact surface or the plunger contact surface is concave. As another example, the second arm contact surface may be concave, and at least one of the housing contact surface or the plunger contact surface is convex, or the second arm contact surface may be convex, and at least one of the housing contact surface or the plunger contact surface is concave.

[0013] In one embodiment, the first arm or the second arm is configured for central pivoting. When the first arm is configured for central pivoting, the first arm may include a first arm pivot, and the second arm may be configured to be mounted on the first arm pivot and pivot about the first arm pivot. Alternatively, when the second arm is configured for central pivoting, the second arm may include a second arm pivot, and the first arm may be configured to be mounted on the second arm pivot and pivot about the second arm pivot. In yet another alternative, both the first arm and the second arm are configured for central pivoting.

[0014] In another embodiment, each of the first arm and the second arm includes an input end and an output end. In this embodiment, a discrete idle component is disposed between the output end of the first arm and the input end of the second arm. In this case, the output end of the first arm includes a first arm contact surface, and the input end of the second arm includes a second arm contact surface.

[0015] In another embodiment, the first arm includes a first arm stop surface, and the second arm includes a second arm stop surface. The first arm stop surface and the second arm stop surface are configured to prevent the first arm and the second arm from rotating excessively away from each other.

[0016] In yet another embodiment, the first arm contact surface and the second arm contact surface are configured to be rotatably attached to a corresponding one of the plunger contact surface and the housing contact surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The foregoing and other features and advantages will be discussed in detail in the following non-limiting description of specific embodiments in conjunction with the accompanying drawings, in which:

[0018] Figure 1 and Figure 2 schematically shows a valve actuation system according to the prior art;

[0019] Figure 3 schematically shows a valve actuation system according to the present disclosure, the valve actuation system including an idle component;

[0020] Figure 4 and Figure 5 illustrates a valve actuation system according to the present disclosure, which includes a floating member in addition to a first arm pivotally mounted at its center and a second arm pivotally mounted at its end on the valve side;

[0021] Figure 6 and Figure 7 illustrates a valve actuation system according to the present disclosure, which includes a floating member in addition to a first arm pivotally mounted at its end on the cam side and a second arm pivotally mounted at its center;

[0022] Figures 8 to 11 illustrates a valve actuation system according to the present disclosure, which includes a floating member in addition to a first arm pivotally mounted at its center and a second arm pivotally mounted at its center;

[0023] Figure 12 and Figure 13 illustrates an alternative embodiment of a valve actuation system according to the present disclosure, which includes a floating member in addition to a first arm pivotally mounted at its center and a second arm pivotally mounted at its center;

[0024] Figures 14 to 16 is a schematic view of a valve actuation system according to the present disclosure and illustrates the rotation of the floating member relative to the first and second arms of the valve actuation system;

[0025] Figure 17 and Figure 18 are a side sectional view and a rear sectional view of a valve actuation system according to the present disclosure, respectively, and illustrate an alternative configuration of a stop surface according to the present disclosure;

[0026] Figures 19 to 22 illustrates an alternative embodiment for providing a "carry" feature according to the present disclosure; and

[0027] Figure 23 and Figure 24 illustrates an alternative embodiment of a pivot mechanism according to the present disclosure that is capable of minimizing the clearance between the floating member and an adjacent valve mechanism component. DETAILED DESCRIPTION

[0028] As used herein, the term "operatively connected" is understood to refer at least to a functional relationship between two components, i.e., the claimed components must be connected in such a way as to perform the indicated function (which may include the presence of intermediate elements or components).

[0029] Figure 3 Schematically illustrates an embodiment of a valve actuation system 300 according to the present disclosure, which includes a discrete floating member 330, wherein Figure 1 andFigure 2 For comparison, like reference numerals denote like elements. As used herein, "discrete" has its ordinary meaning of being separate entities or parts. Thus, in this second embodiment, the discrete floating member 330 is not housed or supported within one of the valve train components 108, 110 as is the case with Figure 1 or housed or supported within the stationary member 232 as is the case with Figure 2 , but is formed as a discrete member that is supported within the valve train 106 by one or more of its adjacent valve train components 108, 110, as described in further detail below. Generally, the support of the discrete floating member 330 is provided by one or more support joints. As used herein, a support joint is a junction of two elements that (i) are joined in the sense of being in close association or relationship with each other (from being separably in contact with each other to including being inseparably connected to each other), and (ii) are configured to carry or hold the discrete floating member within the valve train. Additionally, the support joint can provide the discrete floating member 330 with a degree of freedom of rotation relative to one or more adjacent valve train components.

[0030] In Figure 3 the example shown, such support joints 340, 341 are schematically shown as including contact surfaces 330a, 330b disposed on the floating member 330 and corresponding contact surfaces 108a, 110a disposed on the adjacent valve train components 108, 110. As described in more detail below, the contact surfaces 330a, 330b of the floating member 330 and the corresponding contact surfaces 108a, 110a of the valve train components 108, 110 are complementarily configured to facilitate the support of the floating member 330 by the valve train components 108, 110 and to facilitate the operation of the floating member 330 despite movement of the valve train components 108, 110. Thus, it should be understood that the various complementary contact surfaces described herein are examples of support joints or portions thereof that can be used to implement the floating member 330 (and its various specific embodiments described below).

[0031] Thus, the valve actuation system 300 is considered to include the discrete floating member 330 and the adjacent valve train components 108, 110 that support the discrete floating member 330.

[0032] As Figure 3Further shown, the control of the discrete air-actuated component 330 by the engine controller 120 is provided via a path through at least one of the adjacent valve train components 108, 110. For example, in the various embodiments described below, such control is provided by using hydraulic fluid supplied under the control of the engine controller 120. However, as will be understood by those skilled in the art, other types of control schemes may equally be used for this purpose. In the case where fluid is supplied under the control of the engine controller 120, the present disclosure is characterized in that such a fluid supply passage passes through at least one of the contact surfaces 108a, 110a, 330a, 330b, various examples of which are further shown and described below.

[0033] Although the specific implementation of the discrete air-actuated component 330 based on the specific construction of the sub-components and the locking mechanism will be described in more detail below, the general characteristics of the discrete air-actuated component 330 according to the present disclosure are that it is capable of controlling between a rigid / unlocked state and a flexible / unlocked state, regardless of the mechanism employed for this purpose, and it is constructed as a discrete component supported by adjacent valve train components.

[0034] Figure 4 and Figure 5 An embodiment of a valve actuation system 400 is shown, which can be used to implement Figure 3 the valve actuation system 300. As shown, in addition to the shaft-mounted first arm 402 and the pivot-mounted valve-side second arm 404, the valve actuation system 400 further includes a discrete air-actuated component 406. As Figure 4 best shown in, the valve actuation system 400 is operatively connected to a valve actuation motion source 408 (in this embodiment, in the form of a cam, although other constructions known to those skilled in the art are also possible) and a valve crosshead 420 and corresponding engine valves 422, 424. According to known techniques, the cam 408 includes one or more cam lobes 412, which are configured to provide primary and / or secondary valve actuation motion to the engine valves 422, 424.

[0035] In this embodiment, the first arm 402 is configured to be mounted on a rocker shaft (not shown) via a rocker shaft hole 414 formed in the first arm 402. Additionally, the first arm 402 includes a motion receiving member 410 which, in this case, is in the form of a cam roller configured to contact the cam 408. Additionally, the first arm 402 includes a protrusion 430 extending opposite the motion receiving member 410, i.e., the protrusion is on the opposite side of the rocker shaft hole 414 and extends towards the engine valves 422, 424. The protrusion 430 includes a pivot 432 which allows the second arm 404 to be mounted thereon and further allows the second arm 404 to reciprocate about the pivot 432. The distal end (relative to the first arm 402) of the second arm 404 includes a swivel joint or e-foot 426 which is configured to establish contact with the valve crosshead 420.

[0036] It should be noted that although the various embodiments shown and described herein include two engine valves and corresponding valve crossheads, it should be understood that the valve actuation system described herein can equally be applied to a single-valve system, i.e., a system that does not require a valve crosshead.

[0037] In a particular embodiment, the first arm 402 and the second arm 404 are "half-rockers" in that although they are operatively connected to the valve actuation motion source 408 and the corresponding one of the valve crosshead 420 / valves 422, 424, they do not fully span the distance between the valve actuation motion source 408 and the valve crosshead 420 / valves 422, 424 as in the case of a "full rocker" known in the art. As described in further detail below, when operating in a locked or motion transfer state, in combination with the discrete idle member 406, the first arm 402 and the second arm 404 can operate as a substantially rigid unit such that the valve actuation motion provided by the valve actuation motion source 408 is transferred to the valve crosshead 420 / valves 422, 424, or when the discrete idle member 406 is controlled to be in an unlocked state, the first arm and the second arm act as a flexible unit where all (or almost all, as in the case of "fail-safe" lift provided even in the unlocked state) of the valve actuation motion applied thereto causes the first arm 402 to reciprocate relative to the second arm 404, thereby absorbing such motion relative to the valve crosshead 420 / valves 422, 424.

[0038] Referring again to Figure 4, the discrete floating component 406 is disposed between the first arm 402 and the second arm 404 and is supported by the first arm and the second arm. The discrete floating component 406 includes a housing 440 and a plunger 442 disposed therein through a first end of the housing 440. Both the housing 440 and the plunger 442 can be centered on the longitudinal axis of the floating component 406. As used herein, the modifier "discrete" refers to the construction of the floating component 406 such that it exists as an independent structure relative to other valve train components and is not surrounded by or contained within other valve train components, but is still in communication with other valve train components via support joints to be supported within the entire valve train. As Figure 5 best shown in, the plunger 442 is slidably disposed in a housing bore 502 formed in the housing 440.

[0039] As Figure 5 further shown, the housing 440 has a housing contact surface 540 formed at a second end of the housing 440, and the plunger 442 has a plunger contact surface 542 formed at a first end of the plunger 442 extending out of the housing 440. In a particular embodiment, each of the housing contact surface 540 and the plunger contact surface 542 (e.g., Figure 3 the contact surfaces 330a, 330b shown) is configured to cooperate with complementary contact surfaces (i.e., the first arm 402 and the second arm 404) formed in adjacent valve train components. That is, the plunger contact surface 542 and the corresponding contact surface 544 (e.g., Figure 3 the contact surface 108a shown) of the first arm 402 together form a support joint, and the housing contact surface 540 and the corresponding contact surface 546 (e.g., Figure 3 the contact surface 110a shown) of the second arm 404 together form another support joint.

[0040] In the example shown, both the housing contact surface 540 and the plunger contact surface 542 are formed as convex surfaces that are configured to engage corresponding and complementary concave surfaces 544, 546 formed in the first arm 402 and the second arm 404, respectively, as described below. However, it should be understood that Figure 5The convex surface / concave surface shown can be interchanged, i.e., the housing contact surface 540 and the plunger contact surface 542 are formed as concave surfaces, and the first arm contact surface 544 and the second arm contact surface 546 are formed as convex surfaces. Further, the housing contact surface 540 and the plunger contact surface 542 can include a combination of concave and convex surfaces, and the corresponding contact surfaces 744, 746 of the first and second arms are also a complementary combination of convex and concave surfaces. By combining convex and concave contact surfaces in this way, a degree of manufacturing "foolproofing" is provided, because it is difficult if not impossible to misorient the floating member 406 relative to the first arm 602 and the second arm 604. The illustrated embodiment also includes a floating hydraulic passage 526 formed in the first end of the plunger 442, and more specifically, the opening of the floating hydraulic passage 526 is formed within the plunger contact surface 542. Although the floating hydraulic passage 526 is shown as being formed within the plunger 442, it should be understood that such a passage could alternatively be formed in the second end of the housing 440, and more specifically, the opening of the floating hydraulic passage 526 is formed within the housing contact surface 540.

[0041] Figure 5 Additional features of the second arm 404 are also shown. As described above, the second arm 404 is mounted on a pivot 432 provided by the first arm 402. The pivot 432 can include a hydraulic passage 531 that is operatively connected to a constant source of hydraulic fluid (not shown) provided by a rocker shaft. The hydraulic passage 531 can be in fluid communication with an annular passage (not shown) formed in the outer surface of the pivot 432. The annular passage can be aligned and in fluid communication with a first lubricant supply passage 532 formed in the second arm 404, which in turn is in fluid communication with a second lubricant supply passage 534 formed in the second arm 404. The first lubricant supply passage 532 is in fluid communication with a clearance screw hydraulic passage 561 formed in a clearance screw 560 that extends from an end of the second arm remote from the pivot 432. In this way, lubricating hydraulic fluid is supplied to the swivel joint 426 that contacts the valve crossarm 420. Similarly, the second lubricant supply passage 534 supplies lubricating hydraulic fluid to a support joint established by the housing contact surface 540 and the corresponding contact surface 544 provided by the first arm 404.

[0042] As described above, the convex housing contact surface 540 and the plunger contact surface 542 are shown as engaging corresponding concave contact surfaces 544, 546 formed in the first arm 402 and the second arm 404, respectively. When a biasing force is applied to (or by) the floating member 406 such that contact occurs between the floating member 406 and the adjacent first arm 402 and second arm 404, the mating engagement of the housing contact surface 540 and the plunger contact surface 542 with the corresponding contact surfaces 546, 544 tends to prevent the floating member 406 from moving out from between the first arm 402 and the second arm 404 due to other forces (e.g., vibration or torque) applied to the housing 440 or the plunger 442 and that are generally not parallel to the longitudinal axis of the floating member 406. Although other configurations of the complementary contact surfaces 540, 542, 544, 546 could be used for this purpose, as described below, the shown convex and concave surfaces allow the first arm 402 or the second arm 404 to rotate relative to the housing 440 or the plunger 442 to the extent that the contact surfaces 540, 542, 544, 546 are allowed to slide relative to each other without losing mating engagement, i.e., to operate as a flexible support joint. In one embodiment, any corresponding concave and convex contact surfaces shown and described herein may be formed as spherical contact surfaces.

[0043] As will be understood by those skilled in the art, the mating engagement of the contact surfaces 540, 542, 544, 546 helps to hold the floating member 406 between the first arm 402 and the second arm 404 so long as the contact surfaces 540, 542, 544, 546 are allowed to remain in close relation to each other. To ensure such close relation in all operating states of the valve actuation system 400 (as well as during assembly in manufacturing), it is desirable to ensure that the first arm 402 and the second arm 404 are not allowed to rotate away from each other such that the close relation between the corresponding contact surfaces 540, 542, 544, 546 is lost, which could allow for an unexpected displacement of the floating member 406. To this end, the first arm 402 may include a first arm stop surface 550, and the second arm 404 may include a second arm stop surface 552 that is configured to engage the first arm stop surface 550 to prevent the first arm 402 and the second arm 404 from rotating excessively relative to each other. In Figure 5 the example shown, the first arm stop surface 550 and the second arm stop surface 552 are configured to be close to each other relative to each other such that rotation of the second arm 404 about the pivot 432 and away from the first arm 402 (clockwise, as Figure 5As shown, this will cause the first arm stop surface 550 and the second arm stop surface 552 to engage with each other, thereby preventing further rotation. By selecting such that when the maximum allowable rotation of the first arm 402 away from the second arm 404 is reached, the distance between the first arm stop surface 550 and the second arm stop surface 552 is fully occupied (i.e., the surfaces 550, 552 are in contact with each other), this excessive rotation of the first arm 402 away from the second arm 404 can be prevented.

[0044] As Figure 5 As further shown, the first arm 402 is configured with a first hydraulic passage 520, a second hydraulic passage 522, and a third hydraulic passage 524, wherein the first hydraulic passage 520 is configured to register with an optional (switchable) hydraulic fluid supply source provided by a rocker arm (not shown) known in the art, the third hydraulic passage 524 is configured to register with a dead - band hydraulic passage 526 formed in the plunger 442, and the second hydraulic passage 522 provides a connection between the first hydraulic passage 520 and the third hydraulic passage 524. In one embodiment, the diameters of the third hydraulic passage 524 and the plunger dead - band hydraulic passage 526 are each large enough to ensure fluid communication between these hydraulic passages 524, 526 regardless of the rotational movement of the first arm 402 relative to the plunger 442. As described below, supplying or removing pressurized hydraulic fluid through the hydraulic passages 524, 526 can provide control of the locked and unlocked states of the operation of the dead - band component 406.

[0045] Referring again to Figure 5 , the dead - band component 406 is shown in cross - section to better illustrate the hydraulically controlled locking mechanism 504, which forms a sub - assembly of the dead - band component 406 and is deployed between the housing 440 and the plunger 442. As further shown, a plunger spring 516 is provided to bias the plunger 442 out of the housing 440. Figure 5 The locking mechanism 504 shown is generally of the type described in U.S. Patent No. 9,790,824, the teachings of which are incorporated herein by reference and repeated in the relevant section below.

[0046] As Figure 5As shown, the locking mechanism 504 includes a plunger 442 disposed within a housing bore 502 formed in the floating member 406 and extending along the longitudinal axis from a first end of the housing 440. An inner plunger 510 is slidably disposed within a longitudinal bore 514 formed in the plunger 442. Locking elements in the form of wedges 506 are provided and are configured to engage an annular outer recess 508 formed in the surface defining the housing bore 502. The illustrated embodiment is a locking mechanism 504 that is normally locked, i.e., in the absence of applying hydraulic control via (in this case) the floating hydraulic passage 526 to the inner plunger 510, the inner plunger spring 512 biases the inner plunger 510 into position such that the wedges 506 contact a larger diameter portion of the inner plunger 442 and thereby radially extend out of an opening formed in the plunger 442 to engage the outer recess 508 and effectively lock the plunger 442 in place relative to the housing 440.

[0047] In this locked state, any valve actuation movement applied to the floating member 406 (whether primary or secondary) is transmitted by the floating member 406. It should be noted that although in the locked state as Figure 5 shown, the longitudinal length of the outer recess 508 is greater than the thickness of the wedges 506 such that a small amount of movement is still permitted between the plunger 442 and the housing 440, as described in further detail below. As Figure 5 shown, for example, in the case where valve actuation movement has been applied to the floating member 406 to overcome any outward biasing applied to the plunger 442 by the plunger spring 516, this additional space has been occupied.

[0048] Alternatively, when the floating member 406 is unloaded while still in the locked state (e.g., during the cam base circle), the biasing applied by the plunger spring 516 causes the plunger 442 to translate within its bore 502 to the extent permitted by the longitudinal length of the outer recess 508, i.e., to the Figure 5 left side as shown until the wedges 506 abut the leftmost surface of the outer recess 508. In this way, the plunger spring 516 ensures that the housing contact surface 540 and the plunger contact surface 542 continue to be biased into contact with the corresponding contact surfaces 546, 544 of the adjacent arms 402, 404.

[0049] This biasing force applied by the plunger spring 516 can be selected to additionally ensure that the arms 402, 404 (or additional upstream or downstream valve train components in the system, not shown) are biased into continuous contact with the respective endpoints of the valve train (i.e., the valve actuation motion source and the engine valve). Further, since the outward stroke of the plunger 442 from within its bore 502 is limited by the longitudinal length of the outer recess 508 (when in the locked state), the biasing force applied by the plunger spring 516 to the adjacent arms 402, 404 (and again, any additional upstream or downstream valve train components in the system) will not apply an excessive biasing force to the normal operation of any automatically adjustable flexible components (such as a hydraulic lash adjuster (HLA), etc.) within the valve train. It should be understood that other techniques for such stroke limitation of the plunger 410 relative to the housing 402 can also be used for this purpose, even during the unlocked state of the lash component 400. Additionally, the plunger spring 516 is preferably selected such that regardless of the locked / unlocked state of the locking mechanism 504, the force applied by the plunger spring 516 on any of the valve train components will not apply an excessive biasing force to the flexible valve train components (such as HLA) or the engine valve spring.

[0050] Referring again to Figure 5 , hydraulic fluid that is sufficiently pressurized to overcome the biasing force of the inner piston spring 512 is provided to the top of the inner plunger 510 (the leftmost surface as shown Figure 5 ) via the lash hydraulic passage 526, causing the inner plunger 510 to translate within the bore 514 such that the wedge 506 contacts the smaller diameter portion of the inner plunger 510 and is allowed to retract from the outer recess 508 and disengage from the outer recess, thereby effectively unlocking the plunger 442 relative to the housing 440 and allowing the plunger 442 to freely slide within its bore 502 due to the biasing force provided by the plunger spring 516 in this case. In this unlocked state, any valve actuation motion applied to the lash component 406 will cause the plunger 442 to reciprocate within its bore 502. In this way, and assuming that the stroke of the plunger 442 within its bore 702 is greater than the maximum extent of any applied valve actuation motion (i.e., the plunger 442 cannot reach the lowest point within its bore 502), such valve actuation motion will not be transmitted by the lash component 406 and will effectively be lost. Alternatively, as previously described, the stroke of the plunger 442 within its bore 502 can be configured such that the plunger 442 "reaches the lowest point", i.e., contacts the closed end of the bore 502, thereby always providing "fail-safe" valve lift in the event of failure of the locking mechanism 504.

[0051] As described above, the contact surfaces 540, 542, 544, 546 provided by the floating member 406 and the first arm 402 and the second arm 404 are configured to accommodate rotation of the floating member 406 relative to one or both of the first arm 402 and the second arm 404. Referring to Figures 14 to 16 , this rotation depending on the operating state of the floating member 406 is further shown and described in a highly schematic manner. Figures 14 to 16 FIG. shows a valve actuation system 1400 according to the present disclosure, which specifically includes a first arm 1402, a second arm 1404, and a floating member 1406 that rotate about a rocker shaft 1410 (in this case) as described in various embodiments set forth herein. As further shown, the floating member 1406 includes a housing 1440 and a plunger 1442 as described herein.

[0052] Figure 14 and Figure 15 FIG. shows a situation in which the locking mechanism of the floating member 1406 is maintained in its locked state such that the floating member 1406 and the first arm 1402 and the second arm 1404 operate substantially as a single rigid unit, and the valve actuation motion applied by the valve actuation motion source 1416 is transmitted from the first arm 1402 to the floating member 1406 and then to the second arm 1404. For ease of illustration, the first arm 1402 and the second arm 1404 are depicted as having vertical portions 1402a, 1404a extending therefrom, respectively, and providing fixed contact surfaces for the corresponding contact surfaces of the housing 1440 and the plunger 1442. In this locked state, as Figure 14 shown, the plunger 1442 extends a length L from the housing 1440 1 , and contacts the vertical portion 1402a of the first arm 1402 at an angle θ 1 . Similarly, the housing 1440 (including the portion 1440a of the housing 1440 that contacts the second arm 1404) has a substantially constant length L 2 , and in this locked state, contacts the vertical portion 1404a of the second arm 1404 at an angle θ 2 . As Figure 14 further shown, when no valve actuation motion (e.g., cam base circle) is applied to the first arm 1402, the second arm 1404 does not achieve deflection or valve lift.

[0053] Because the floating member 1406 and the first arm 1402 and the second arm 1404 operate as a single unit during this locked state, the maximum valve actuation motion is applied to the first arm 1402 by the valve actuation motion source 1416 (as Figure 15The application of such valve actuation motion to the second arm 1404, as shown, causes deflection or valve lift D of the second arm 1404. Despite the application of such valve actuation motion, the locked state of the floating member 1406 ensures that L 1 、L 2 、θ 1 and θ 2 remain substantially the same, resulting in little rotation of the plunger 1442 or the housings 1440, 1440a relative to the first or second arms 1402, 1404, respectively.

[0054] In contrast, Figure 16 illustrates a situation where the locking mechanism of the floating member 1406 is maintained in its unlocked state such that the floating member 1406 absorbs any valve actuation motion applied to the first arm 1402 via the plunger 1442 and the first arm 1402, with the result that no valve actuation motion is transmitted to the second arm 1404. This is described in Figure 16 by the second arm 1404 not experiencing any deflection or valve lift. However, the angles θ 1 ' at which the plunger 1442 and the housings 1440, 1440a contact the first arm 1402 and the second arm 1404, respectively, and θ 2 ' as well as the length L 1 ' by which the plunger 1442 extends out of the housing 1440 during this unlocked state vary relative to the unlocked state during the application of the maximum valve actuation motion as shown in Figure 16 . More specifically, the application of the maximum valve actuation motion results in L1'<L1 and rotation of the floating member 1406, as shown by θ 1 '<θ 1 and θ 2 '<θ 2 . However, again, the construction of the corresponding contact surfaces described herein facilitates such rotation of the floating member 1406.

[0055] Figure 6 And Figure 7 illustrate an alternative embodiment of the valve actuation system 600 that can be used as the valve actuation system 300 shown in Figure 3 , where like reference numerals represent like elements. In addition to the pivotally mounted cam side first arm 602 and the shaft mounted second arm 604, the valve actuation system 600 further includes a floating member 406. As with the system 400 shown in Figure 4 and Figure 5 , the valve actuation system 600 is operatively connected to a valve actuation motion source 408 (e.g., a cam) and a valve crosshead 420 and corresponding engine valves 422, 424.

[0056] In this embodiment, the second arm 604 is configured to be mounted on a rocker shaft (not shown) via a rocker shaft hole 614 formed in the second arm 604. The distal end of the second arm 604 (away from the rocker shaft hole 614) includes a swivel joint or e-foot 426 configured to establish contact with the valve crosshead 420. Additionally, the second arm 604 includes a protrusion 630 extending opposite the swivel joint or e-foot 426, i.e., the protrusion is on the opposite side of the rocker shaft hole 614 and extends toward the valve actuation motion source 408. The protrusion 630 includes a pivot 632 that allows the first arm 602 to be mounted thereon and allows the first arm 602 to reciprocate about the pivot 632. Additionally, the first arm 602 includes a motion receiving member 610, which in this case is in the form of a cam roller configured to contact the cam 408.

[0057] In one embodiment, similar to Figure 4 and Figure 5 the system 400 shown, the first arm 602 and the second arm 604 are "semi-rockers". Thus, similarly, in combination with the idle member 406, the first arm 602 and the second arm 604 can operate as a substantially rigid unit such that the valve actuation motion provided by the valve actuation motion source 408 is transmitted to the valve crosshead 420 / valves 422, 424, or when the idle member 406 is controlled to be in an unlocked state, the first and second arms act as a flexible unit where all valve actuation motion applied thereto causes reciprocating motion of the first arm 602 relative to the second arm 604, thereby absorbing this motion relative to the valve crosshead 420 / valves 422, 424.

[0058] As previously described, and as Figure 7 best shown in, each of the housing contact surface 540 and the plunger contact surface 542 is configured to mate with complementary contact surfaces formed in adjacent valve mechanism components (i.e., the first arm 602 and the second arm 604). In the example shown, both the housing contact surface 540 and the plunger contact surface 542 are formed as convex surfaces configured to engage corresponding and complementary concave surfaces 744, 746 formed in the first arm 602 and the second arm 604, respectively. However, it should be understood that Figure 7The convex surface / concave surface shown can be interchanged, i.e., the housing contact surface 540 and the plunger contact surface 542 are formed as concave surfaces, and the first arm contact surface 744 and the second arm contact surface 746 are formed as convex surfaces. Further, the housing contact surface 540 and the plunger contact surface 542 can include a combination of concave and convex surfaces, and the corresponding contact surfaces 744, 746 of the first and second arms are also complementary combinations of convex and concave surfaces. By combining convex and concave contact surfaces in this way, a certain degree of manufacturing "foolproofing" is provided because it is difficult, if not impossible, to misorient the floating member 406 relative to the first arm 602 and the second arm 604.

[0059] As Figure 6 and Figure 7 shown, the first arm 602 is mounted on a pivot 632 provided by the second arm 604. The pivot 632 can include a hydraulic passage 731 that is operatively connected to an optional (switched) hydraulic fluid supply source (not shown) provided by the rocker shaft. As Figure 7 shown, the hydraulic passage 731 is in fluid communication with a lubrication passage 770 that supplies lubricating hydraulic fluid to the motion receiving member 610. The hydraulic passage 731 can additionally be in fluid communication with an annular passage (not shown) formed in the outer surface of the pivot 632. As Figure 7 shown, the first arm 602 is further configured with a first hydraulic passage 722 that is in fluid communication with a second hydraulic passage 724. The annular passage formed in the pivot 632 can be aligned and in fluid communication with the first hydraulic passage 722. In turn, the second hydraulic passage 724 is configured to register with a floating hydraulic passage 526 formed in the plunger 442. In this case, the diameters of the second hydraulic passage 724 and the floating hydraulic passage 526 of the plunger are each large enough to ensure fluid communication between these hydraulic passages 724, 526 regardless of the rotational movement of the first arm 402 relative to the plunger 442. As previously described, supplying or removing pressurized hydraulic fluid through the hydraulic passages 722, 724, 526 can provide control of the locked and unlocked states of the operation of the floating member 406.

[0060] As Figure 7Further shown, a first lubricant supply passage 732 is formed in the second arm 604, which in turn is in fluid communication with a second lubricant supply passage 734 formed in the second arm 604. The first lubricant supply passage 732 is in fluid communication with a constant supply source (not shown) of hydraulic fluid provided by the rocker shaft and is also in fluid communication with a clearance screw hydraulic passage 561 formed in the clearance screw 560, which extends from an end of the second arm remote from the pivot 432. In this manner, lubricating hydraulic fluid is supplied to the swivel joint 426 that contacts the valve crosshead 420. Similarly, the second lubricant supply passage 734 supplies lubricating hydraulic fluid to a joint established by the housing contact surface 540 and the corresponding contact surface 746 provided by the second arm 604.

[0061] As in Figure 4 and Figure 5 the embodiment of, a stop surface can be provided to prevent over-rotation of the first arm 602 and the second arm 604. This is shown in Figure 7 which the first arm 602 includes a first arm stop surface 750 and the second arm 604 includes a second arm stop surface 752 configured to engage the first arm stop surface 550.

[0062] Figures 8 to 11 Another alternative embodiment of a valve actuation system 800 is shown, which can be used as Figure 3 the valve actuation system 300 shown, where like reference numerals denote like elements. In addition to the shaft-mounted first arm 802 and the shaft-mounted second arm 804, the valve actuation system 800 further includes a floating member 406. As in Figures 4 to 7 the systems 400, 600 shown, the valve actuation system 800 is operatively connected to a valve actuation motion source 408 (e.g., a cam) and the valve crosshead 420 and the corresponding engine valves 422, 424.

[0063] As described above, in this embodiment, each of the first arm 802 and the second arm 804 is configured to be mounted on a rocker shaft (not shown) via respective rocker shaft holes 814, 816 formed in the first arm 802 and the second arm 804. In this embodiment, the distal end (remote from its rocker shaft hole 816) of the first arm 802 includes a motion receiving member 810, which in this case is in the form of a cam roller configured to contact the cam 408. The distal end (remote from its rocker shaft hole 814) of the second arm 804 includes a swivel joint or e-foot 426 configured to establish contact with the valve crosshead 420.

[0064] In the presently preferred embodiment, also as in Figures 4 to 7In the systems 400, 600 shown, the first arm 802 and the second arm 804 are "semi-rocker arms". Thus, similarly, in combination with the floating member 406, the first arm 802 and the second arm 804 can operate as a substantially rigid unit, such that the valve actuation motion provided by the valve actuation motion source 408 is transmitted to the valve crosshead 420 / valves 422, 424, or when the floating member 406 is controlled to be in the unlocked state, the first arm and the second arm act as a flexible unit, where all (or almost all in the case of a "fail-safe" configuration) of the valve actuation motion applied thereto causes reciprocating motion of the first arm 802 relative to the second arm 804, thereby absorbing this motion relative to the valve crosshead 420 / valves 422, 424.

[0065] Figure 9 A top view of the system 800 is shown, where the floating member 406 has been removed to better show the relationship between the first arm 802 and the second arm 804. In particular, the first arm 802 and the second arm 804 each have corresponding overlapping portions 902, 904, in which corresponding rocker shaft holes 816, 814 (shown in dashed lines) are formed. As shown, the corresponding widths of the first arm 802 and the second arm 804 at the overlapping portions 902, 904 (as Figure 9 shown from top to bottom) are less than the corresponding maximum widths of the first arm 802 and the second arm 804. In this way, when the first arm 802 and the second arm 804 are deployed adjacent to each other on the rocker shaft, the floating member 406 (likewise, not shown in Figure 9 ) can simply remain substantially linearly aligned with the valve actuation motion source 408 and the engine valves 422, 424. Additionally, the overall width of the system 800 (likewise, when the first arm 802 and the second arm 804 are deployed adjacent to each other on the rocker shaft) can be minimized, thus saving the usually limited space along the rocker shaft. Such a configuration of the overlapping portions 902, 904 is not necessary; for example, the widths of the overlapping portions 902, 904 can be substantially equal to or even greater than the widths of the remaining portions of the first arm 802 and the second arm 804.

[0066] Figure 10 A cross-sectional view taken along the Figure 9 section line X-X in is shown. In this view, the portion of the first arm 802 adjacent to the valve actuation motion source 408 and supporting the motion receiving member 810 is shown in cross-section, as is a portion of the housing 440 of the floating member 406. Additionally, the second arm 804 is also shown in cross-section, thereby showing a portion of the lubricating hydraulic passage 1032 (the remainder of which is shown in dashed lines), which provides fluid communication from a constant hydraulic fluid supply source in the rocker shaft (not shown) to the clearance screw hydraulic passage 561 in the clearance screw 560, as described above.

[0067] Figure 11 shows a sectional view taken along the sectional line XI-XI in Figure 9 In this view, a first hydraulic passage 1122 and a second hydraulic passage 1124 are formed in the first arm 802, wherein the first hydraulic passage 1122 is configured to receive hydraulic fluid from an optional (switchable) hydraulic source provided by a rocker shaft (not shown), and the second hydraulic passage 1124 is configured to be in fluid communication with both the first hydraulic passage 1122 and the pneumatic hydraulic passage 526. As described above, the diameters of the second hydraulic passage 1124 and the pneumatic hydraulic passage 526 can be selected to remain in registration with each other, although the plunger 442 rotates relative to the first arm 802. As described above, supplying or removing pressurized hydraulic fluid through the hydraulic passages 1122, 1124, 526 can provide control of the locked and unlocked states of the operation of the pneumatic member 406.

[0068] Likewise, each of the housing contact surface 540 and the plunger contact surface 542 is configured to cooperate with complementary contact surfaces formed in adjacent valve mechanism components (i.e., the first arm 802 and the second arm 804). In the example shown, both the housing contact surface 540 and the plunger contact surface 542 are formed as convex surfaces, which are configured to engage corresponding and complementary concave surfaces 1144, 1146 formed in the first arm 802 and the second arm 804, respectively. However, it should be understood that Figure 11 the convex / concave surfaces shown can be interchanged, i.e., the housing contact surface 540 and the plunger contact surface 542 are formed as concave surfaces, the first arm contact surface 1144 and the second arm contact surface 1146 are formed as convex surfaces, or a combination of convex / concave surfaces can be used to prevent manufacturing errors as described above.

[0069] It should be noted that in the Figures 8 to 11 embodiment shown, no stop surface similar to that described above with respect to Figure 5 and Figure 7 is provided. Thus, such a stop surface is not a requirement of the present disclosure, but can be provided as a function of a particular application.

[0070] Similar to the Figures 8 to 11 embodiment, Figure 12 and Figure 13 shows an alternative embodiment of a valve actuating system 1200, which can be used as the Figure 3 valve actuating system 300 shown. According to the present disclosure, in addition to the centrally pivoted first (or input) arm 1202 and the centrally pivoted second (or output) arm 1204, the valve actuating system 1200 further includes a pneumatic member 1206. In Figures 8 to 11In an embodiment, the first arm 802 and the second arm 804 are configured to be located adjacent to each other on the rocker arm. However, different from this embodiment, the second arm 1204 includes two sides 1270, 1272 configured to nest the first arm 1202 therebetween. As previously described, the first arm 1202 and the second arm 1204 each include rocker arm shaft holes 1216, 1214 formed therein and are configured to receive a rocker arm shaft (not shown). In this case, the rocker arm shaft hole 1214 formed in the second arm 1204 includes two axially aligned openings, one opening formed in each of the two lateral sides 1270, 1272. As previously described, the first arm 1202 includes a motion receiving member 1210, which in the illustrated embodiment may take the form of a cam roller configured to contact a valve actuation motion source (not shown). Figure 12 and Figure 13 A specific feature of the embodiment is that the first arm 1202 and the second arm 1204 are configured such that the first arm 1202 receives valve actuation motion from an upper cam (not shown).

[0071] As in the previous embodiment described above, the valve actuation system 1200 includes a discrete floating member 1206 located between the first arm 1202 and the second arm 1204 and supported by the first and second arms. However, in this case, as Figure 13 best shown in, the discrete floating member 1206 is substantially vertically oriented, which is opposite to the substantially horizontal orientation of the discrete floating member shown and described above with respect to Figures 4 to 11 shown and described.

[0072] As Figure 13As best shown, the first arm 1202 includes an input end 1390 and an output end 1392 that are opposite each other about rocker shaft holes 1214, 1216, and the second arm 1204 includes an input end 1394 and an output end 1396 that are also opposite each other about rocker shaft holes 1214, 1216. Additionally, the discrete floating member 1206 is supported between the output end 1392 of the first arm 1202 and the input end 1394 of the second arm 1204. With respect to the first arm 1202 and the second arm 1204, the terms "input" and "output" refer to the role of the respective ends 1390 - 1396 in transmitting the valve actuation motion applied thereto. That is, the input end 1390 of the first arm 1202 receives valve actuation motion from a valve actuation motion source (not shown) (such as an upper cam), and the output end 1392 of the first arm 1202 transmits (or outputs) the valve actuation motion to the discrete floating device 1206. Further, the input end 1394 of the second arm 1204 receives valve actuation motion (when provided) from the discrete floating device 1206, and the output end 1396 of the second arm 1204 transmits (or re - outputs) any valve actuation motion applied to the second arm 1204 to one or more engine valves and / or additional valve train components (not shown).

[0073] As Figure 13 As further shown and consistent with the above - described embodiments, the floating member 1206 similarly includes a housing 1330 and a plunger 1334 that implement a locking mechanism 1300. However, in this case, the function of the above - mentioned plunger spring 516 is achieved by a plunger spring 1316 deployed outside the housing 1330 and the plunger 1334. In the illustrated embodiment, the plunger spring 1316 is deployed between a flange 1382 formed on or attached to the outer surface of the plunger 1334 and a shoulder 1384 formed in the housing 1330, as shown. As Figure 13 As further shown, the floating member 1206 also includes a locking mechanism 1300 that includes an internal plunger 1310 (slidably disposed in a longitudinal hole 1314 formed in the plunger 1334), a locking element or wedge 1306, and an annular channel 1308. The locking mechanism 1300 operates in the same manner (i.e., under the control of hydraulic fluid supplied by a hydraulic channel 1326 formed in the plunger 1334) as the corresponding components described above with respect to Figure 5 and Figure 7 In this case, further, the housing 1330 is not formed as a single piece but has an end cap 1331 attached to the housing 1330, which is substantially implemented as a tube in this embodiment, and the second end of which is closed by an end cap 1301. In this embodiment, a housing contact surface 1340 is formed in the end cap 1301. Although in Figure 13Although not shown in its entirety, a hydraulic passage 1336 formed in the first arm 1202 is in fluid communication with an alternative (switchable) hydraulic fluid supply source provided by a rocker shaft (not shown) and further in fluid communication with a hydraulic passage 1326 formed in the plunger 1334.

[0074] Figure 13 Contact surfaces 1344, 1346 are also shown that are configured to engage corresponding housing contact surfaces 1340 and plunger contact surfaces 1342. However, in this case, while the housing contact surface 1340 is formed as a convex surface (consistent with the Figures 4 to 11 embodiment) that is configured to mate with a corresponding concave contact surface 1346 of a clearance screw 1380 that forms part of the second arm 1204, the plunger contact surface 1342 is formed as a concave surface that is configured to mate with a corresponding convex surface 1344 of the first arm 1202. As described above, by contrarily configuring the housing contact surface 1340 and the plunger contact surface 1342 in this way, the possibility of incorrect installation of the free play member 1206 (i.e., being reversed with respect to the Figure 12 and Figure 13 shown orientation) can be effectively avoided.

[0075] Finally, as in the above-described embodiments, a stop surface can be provided to prevent excessive rotation of the first arm 1202 and the second arm 1204. This is shown in Figure 12 where the first arm 602 includes a first arm stop surface 1250 in the form of a laterally extending member and the second arm 1204 includes a second arm stop surface 1252 that is configured to engage the first arm stop surface 1250.

[0076] Figure 17 and Figure 18 show an alternative embodiment of such a stop surface, which shows a system 1700 that can be used as the Figure 3 valve actuation system 300. The valve actuation system 1700 includes a first arm 1702 and a second arm 1704 that are substantially similar to the Figure 12 and Figure 13 shown first arm 1202 and second arm 1204 except that stop surfaces 1750, 1752 are formed. In this embodiment, the first stop surface 1750 is formed as a downward-facing surface that extends radially (with respect to the rocker shaft 1714) on the first arm 1702 away from the motion receiving portion 1702a of the first arm 1702 (i.e., on the opposite side of the rocker shaft 1714). Similarly, the second stop surface 1752 is formed as an upward-facing surface that extends radially of the second arm 1704 away from the motion transfer portion 1704a of the second arm 1704. In particular, as Figure 17As shown, the first stop surface 1750 and the second stop surface 1752 are configured to be aligned relative to each other such that clockwise rotation of the first arm 1702 will cause the first stop surface 1750 and the second stop surface 1752 to separate from each other, while clockwise rotation of the second arm 1704 will cause the first stop surface 1750 and the second stop surface 1752 to move closer to each other until they eventually come into contact. At such contact, further clockwise rotation of the second arm 1704 will cause the first arm 1702 to be "carried" in the clockwise direction together with the second arm 1704. In this way, a discrete floating component (not shown) is not allowed to exceed a predetermined length of the gap between the first arm 1702 and the second arm 1704, thereby preventing the gap from exceeding the maximum length of the floating component, which otherwise might allow the floating component to move out of the system.

[0077] In addition to being able to switch between a locked state and an unlocked state, the discrete floating components described herein can also be configured to have travel limiting features that prevent the discrete floating components from exceeding a maximum overall length. For example, in the case of the housing and plunger embodiments described above, such travel limiting features would prevent the plunger from extending out of its housing bore by more than a maximum distance. Various examples of such travel limiting features are taught in co-pending U.S. patent application titled "Discrete Floating Device", the teachings of which are incorporated herein by reference, attorney docket number JVSPP110US.

[0078] While such travel limiting features in discrete floating components are advantageous, they may cause further problems in certain systems, where, with reference Figure 17 and Figure 18 As an example, the spacing between the first arm 1702 and the second arm 1704 that supports the discrete floating component may exceed the maximum length of the discrete floating component (as defined by its travel limiting features). In such a case, in the absence of the above-described "carrying" feature provided by the first stop surface 1750 and the second stop surface 1752, the discrete floating component may lose its support from the first arm 1702 and the second arm 1704 and may move out.

[0079] Assuming the presence of such travel limiting features in the discrete floating component, various alternative embodiments can be provided in which the Figure 17 and Figure 18 "carrying" feature can be achieved. Figures 19 to 22 Such an alternative embodiment is shown.

[0080] Figure 19An embodiment of system 1900 is shown, which system includes a first arm 1902 and a second arm 1904, and a schematically shown stroke-limited floating member 1906 interposed therebetween as described above. However, in this particular embodiment, the floating member 1906 is rotatably attached to the first arm 1902 and the second arm 1904 by means of a U-bolt arrangement including U-bolts 1960, 1962 and corresponding retaining clips or split pins 1961, 1963, etc. In particular, the U-bolts 1960, 1962 pass through openings formed in both the first arm 1902 and the second arm 1904, which openings are aligned with corresponding openings formed at the respective ends of the floating member 1906. Preferably, the U-bolts 1960, 1962 are loosely fitted into such openings such that the floating member 1906 can still freely rotate about the U-bolts 1960, 1962 while still being fixed to the first arm 1902 and the second arm 1904. Thus, any tendency for the first arm 1902 and the second arm 1904 to rotate away from each other such that the gap therebetween (in which the floating member 1906 is disposed) grows beyond the maximum length of the floating member 1906 will be resisted by the stroke limitation of the floating member 1906.

[0081] Figure 20 An embodiment of system 2000 is shown, which system includes a first arm 2002 and a second arm 2004, and a schematically shown stroke-limited floating member 2006 interposed therebetween as described above. However, in this particular embodiment, the floating member 2006 is rotatably attached to the first arm 2002 and the second arm 2004 by means of a constrained ball cup (convex and concave) arrangement. In particular, in the embodiment shown, each end of the floating member 2006 is equipped with a spherical ball or knob 2060, 2064, while the first arm 2002 and the second arm 2004 are equipped with corresponding spherical cups 2061, 2065. When the balls 2060, 2064 are located within the cups 2061, 2065, suitable retaining clips 2062, 2066 may be provided between the balls 2060, 2064 and the cups 2061, 2065 so as to retain the balls 2060, 2064 within the cups 2061, 2065. Thus, similarly, the separation between the first arm 2002 and the second arm 2004 is prevented to the extent that the first arm 2002 and the second arm 2004 are rotatably attached to the stroke-limited floating member 2006.

[0082] Figure 21 is shown in connection with Figure 20An embodiment of system 2100 is substantially the same as system 2000 shown, except that the cups are formed in threaded inserts 2160, 2162 configured to mate with complementary threaded portions of first arm 2102 and second arm 2104. In this embodiment, the ball cup joints as described above can be established with the corresponding threaded inserts 2160, 2162 first, and then the threaded inserts can mate with the corresponding threaded portions of first arm 2160 and second arm 2162. In addition to making the assembly of system 2100 easier, the threaded engagement between inserts 2160, 2162 and first arm 2102 and second arm 2104 allows for relatively fine adjustment of system 2100, for example for clearance purposes.

[0083] Figure 22 An embodiment of system 2200 is shown, which includes a first arm 2202 and a second arm 2204 and a schematically shown limited-stroke floating member 2206 interposed therebetween as described above. In this particular embodiment, first arm 2202 and second arm 2204 include openings 2203, 2205 configured to receive extensions 2262, 2264 formed on opposite ends of floating member 2206. Further, each of extensions 2262, 2264 includes threaded ends 2265, 2267 configured to receive corresponding lock nuts 2263, 2266, thereby coupling or rotatably attaching floating member 2206 to first arm 2202 and second arm 2204.

[0084] As will be understood by those skilled in the art, through normal valve actuation movements, etc., Figures 19 to 22 the various embodiments shown may result in the formation of a temporary gap or space between the floating member and a hydraulic passage (e.g., Figure 5 the hydraulic passage 524 shown), which supplies hydraulic fluid to the floating member as a control input. Such a gap may result in a loss of hydraulic fluid, which in turn results in a decrease in the hydraulic pressure acting on the floating member. As a result, the floating member may not be able to reliably switch between its locked and unlocked states, which may lead to a decrease in engine performance or even engine damage.

[0085] To prevent such a loss of hydraulic connection, Figure 23 a pivot connection is shown that can prevent such a gap from occurring. As Figure 23As shown, an outer sleeve 2302 (which may be integral with or inserted into a valve mechanism component, such as a rocker arm or the like, configured to supply hydraulic fluid (oil supply) to a floating component) is provided with a sliding piston 2360 disposed within a piston bore 2362 formed in the outer sleeve 2302. A stroke limiting clip 2304 may be deployed between the surface of the bore 2362 and a recessed annular portion 2306 of the piston 2360 such that the piston 2360 is permitted to slide within the bore 2362 but is not permitted to extend out of the bore 2362 by more than a predetermined distance. On the other hand, the travel of the piston 2360 into the bore 2362 is limited when the shoulder surface 2364 of the piston 2360 contacts the upper surface 2366 of the outer sleeve 2302.

[0086] As shown, the piston 2360 has a hydraulic passage 2324 formed therein that communicates with both the top and bottom of the piston 2360, i.e., hydraulic fluid can flow from the bottom to the top of the piston 2360 via the hydraulic passage 2324. Additionally, as Figure 23 shown in the lower right corner, a supply port 2308 provides fluid communication between a hydraulic fluid supply source (not shown) and the bore 2362 near the bottom end of the piston 2360. Preferably, the shoulder surface 2364 and the upper surface 2366 are configured such that when these surfaces contact each other, the supply port 2308 remains unobstructed by the piston 2360, such that hydraulic fluid can still flow within the bore 2362 when supplied by the supply port 2308.

[0087] When hydraulic fluid is supplied to the bore 2362 via the supply port 2308, the presence of the pressurized fluid below the piston 2360 will tend to bias the piston 2360 upward (as Figure 23 shown). Thus, this upward biasing of the piston 2360 will tend to prevent any gap from forming between the contact surface 2342 of the piston 2360 and a corresponding contact surface (not shown) of the floating component. In effect, the piston 2360 serves as a hydraulic lash adjuster (without a check valve typically incorporated into a hydraulic lash adjuster) to maintain fluid communication between the floating component and an adjacent valve mechanism component that supplies hydraulic fluid thereto.

[0088] Figure 24 is shown similar to Figure 23An alternative mechanism for preventing loss of hydraulic connection is shown. In particular, a sliding piston 2460 is deployed in a bore 2462 formed in a valve train component such as a rocker arm or the like. In this case, a hydraulic supply passage 2470 is in communication with a hydraulic passage 2424 formed in the piston 2460 (via a fluid connection not shown), which passage 2424 again supplies hydraulic fluid to an adjacent lash adjuster. However, in this case, the upward biasing of the piston 2460 is provided by a spring 2480 as shown. Thus, the biasing force applied by the spring does not depend on the presence of hydraulic fluid supplied to the piston 2460, but is constantly supplied at all times. To prevent an excessive force from the spring 2480 from being applied to the valve train in which it is located (and thus potentially interfering with the operation of any in-line hydraulic lash adjuster), in this embodiment, the travel limitation is provided by a screw 2482 fixed to the bottom end of the piston 2460.

[0089] As will be appreciated by those skilled in the art, other types of travel limitation mechanisms or configurations may equivalently be used for Figure 23 and Figure 24 the embodiment shown.

Claims

1. A valve actuation system for actuating at least one engine valve in an internal combustion engine, the system comprising: a first arm operatively connected to a valve actuation motion source to receive valve actuation motion from the valve actuation motion source and having a first arm contact surface; a second arm operatively connected to the at least one engine valve to apply valve actuation motion to the at least one engine valve and having a second arm contact surface; and a discrete floating device, the discrete floating device comprising: a housing having a housing contact surface; and a plunger controllable between a first state in which the plunger is rigidly held relative to the housing and a second state in which the plunger is allowed to reciprocate relative to the housing, the plunger further including an end having a plunger contact surface, wherein the housing contact surface is configured to engage one of the first arm contact surface or the second arm contact surface, and the plunger contact surface is configured to engage the other of the first arm contact surface and the second arm contact surface, and wherein the first arm contact surface, the second arm contact surface, the housing contact surface and the first plunger contact surface are configured to support the discrete floating device between the first arm and the second arm.

2. The valve actuation system according to claim 1, wherein, the housing includes a housing bore extending longitudinally into the housing from a first end of the housing, and the plunger is disposed in the housing bore through the first end of the housing, and wherein a second end of the housing or the end of the plunger includes a floating hydraulic passage configured to receive hydraulic fluid to control the plunger between the first state and the second state of the plunger, and wherein the first arm or the second arm includes a hydraulic supply passage configured to register with the floating hydraulic passage.

3. The valve actuation system according to claim 1, wherein, the first arm contact surface and the second arm contact surface are configured to allow the floating device to rotate relative to the first arm and the second arm.

4. The valve actuation system according to claim 3, wherein, the first arm contact surface is concave, and at least one of the housing contact surface or the plunger contact surface is convex.

5. The valve actuation system according to claim 3, wherein, the first arm contact surface is convex, and at least one of the housing contact surface or the plunger contact surface is concave.

6. The valve actuation system according to claim 3, wherein, the second arm contact surface is concave, and at least one of the housing contact surface or the plunger contact surface is convex.

7. The valve actuation system according to claim 3, wherein, the second arm contact surface is convex, and at least one of the housing contact surface or the plunger contact surface is concave.

8. The valve actuation system according to claim 1, wherein, the first arm is configured for central pivoting.

9. The valve actuation system according to claim 8, wherein, the first arm includes a first arm pivot, and the second arm is configured to be mounted on the first arm pivot and pivot about the first arm pivot.

10. The valve actuation system according to claim 8, wherein, the second arm is configured to pivot centrally.

11. The valve actuation system according to claim 1, wherein, the second arm is configured to pivot centrally, and the second arm further includes a second arm pivot, wherein the first arm is configured to be mounted on the second arm pivot and pivot about the second arm.

12. The valve actuation system according to claim 1, wherein, both the first arm and the second arm are configured to pivot centrally.

13. The valve actuation system according to claim 12, wherein, each of the first arm and the second arm includes an input end and an output end, and wherein the discrete idle member is disposed between the output end of the first arm and the input end of the second arm, the output end of the first arm includes the first arm contact surface, and the input end of the second arm includes the second arm contact surface.

14. The valve actuation system according to claim 1, wherein, the first arm includes a first arm stop surface, and the second arm includes a second arm stop surface, and wherein the first arm stop surface and the second arm stop surface are configured to prevent the first arm and the second arm from rotating excessively away from each other.

15. The valve actuation system according to claim 1, wherein, the first arm contact surface and the second arm contact surface are configured to be rotatably attached to a corresponding one of the plunger contact surface and the housing contact surface.

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