Valve actuation system with isolated lost motion device

Abstract

The valve actuation system includes a first arm having a first arm contact surface and operably connected to a valve actuation motion sensor. A second arm having a second arm contact surface is operably connected to at least one engine valve. A decoupled lost motion device is provided that is controllable between a first motion-transmitting state and a second motion-absorbing state. The decoupled lost motion device includes a plunger contact surface and a housing contact surface. The housing contact surface is configured to engage with one of the first arm contact surface or the second arm contact surface, and the plunger contact surface is configured to engage with the other of the first arm contact surface and the second arm contact surface. The first arm contact surface and the second arm contact surface, the housing contact surface, and the first plunger contact surface are configured to support the decoupled lost motion device between the first arm and the second arm.

Description

[Technical Field]

[0001] Valve actuation in an internal combustion engine is required for the engine to operate. Typically, valve actuation forces to open engine valves (i.e., intake valves, exhaust valves, or auxiliary engine valves) are transmitted by a valve train, where such valve actuation forces may be provided by primary and / or auxiliary motion sources. As used herein, the description "primary" refers to so-called primary event engine valve motion, i.e., valve motion used during positive force generation when fuel is combusted in an engine cylinder to provide net engine power output, while the description "auxiliary" refers to other engine valve motions that either substitute for positive force generation (e.g., compression release braking, bleeder braking, cylinder decompression, cylinder deactivation, brake gas recirculation (BGR), etc.) or are in addition to positive force generation (e.g., internal exhaust gas recirculation (IEGR), variable valve actuations (VVA), early exhaust valve opening (EEVO), late intake valve closing (LIVC), swirl control, etc.).

[0002] In many internal combustion engines, the primary and / or secondary sources of motion may be provided by fixed-profile cams, and more specifically, by one or more fixed lobes or bumps that may be an integral part of each cam. The ability to vary the timing and lift of the intake and / or exhaust valves may provide benefits such as improved performance, improved fuel economy, reduced emissions, and better vehicle drivability. However, the use of fixed-profile cams can make it difficult to adjust the timing and / or amount of engine valve lift to optimize them for various engine operating conditions.

[0003] One way to adjust valve timing and lift given a fixed cam profile has been to incorporate a “lost motion” or variable-length device in the valvetrain linkage between a given engine valve and its corresponding cam. Lost motion is a term applied to a class of engineering solutions for modifying the valve actuation motion defined by a cam profile using a variable-length mechanical, hydraulic, or other linkage assembly. In a lost motion system, a cam lobe may provide the “maximum” motion (longest dwell and maximum lift) required over the entire range of engine operating conditions, including for positive force generation and / or auxiliary operation, as needed. A variable-length system may then be included in the valvetrain linkage intermediate the opening valve and the cam providing the maximum motion to reduce or eliminate some or all of the motion imparted to the valve by the cam. Typically, such lost motion devices are controllable between a “locked,” or motion-transmitting, state and an “unlocked,” or motion-absorbing, state. During the locked state, the lost motion device is maintained in a substantially rigid configuration (with allowance for lash adjustment) so that valve actuation motion applied to the lost motion device is transmitted to the corresponding engine valve, whereas during the unlocked state, the lost motion device is capable of absorbing or avoiding, or "neutralizing," valve actuation motion applied to the lost motion device, thereby preventing such valve actuation motion from being transmitted to the corresponding engine valve.

[0004] FIG. 1 schematically illustrates one embodiment of a conventional valve actuation system 100 incorporating a lost motion component 130. As illustrated, 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 and closing motion) to one or more engine valves 104 via a valve actuation load path 106. The one or more engine valves 104 are associated with cylinders 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 associated therewith for actuation of the corresponding engine valve 104. Furthermore, while only a single cylinder 105 is shown in FIG. 1 , it should be understood that an internal combustion engine may, and often does, include two or more cylinders, and the valve actuation systems described herein are applicable to any number of cylinders in a given internal combustion engine.

[0005] Valve actuation motion source 102 may include any combination of known elements capable of providing valve actuation motion, such as cams, etc. Valve actuation motion source 110 may be dedicated to providing exhaust motion, intake motion, auxiliary motion, or a combination of exhaust or intake motion along with auxiliary motion.

[0006] As shown, the valve actuation load path 106 is disposed between the valve actuation motion source 102 and at least one engine valve 104 and may include one or more valve train components (in the illustrated example, a first valve train component 108 and a second valve train component 110) used to transfer 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 lash adjusters, etc. While two valve train components 108, 110 are shown in FIG. 1 , it is understood that a greater or lesser number of valve train components may be disposed. Additionally, 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, while the lost motion component 130 may come into contact with other components within the valve train 106, by being housed within the second valve train component 110, the lost motion component 130 is fully supported by and maintained within the valve train 106. For example, the second valve train component 110 may be embodied by a rocker arm or valve bridge having a bore formed therein within which the components forming the lost motion component 130 are disposed.

[0007] As further shown in FIG. 1 , an engine controller 120 may be provided and operatively connected to the lost motion component 130. The engine controller 120 may comprise any electronic, mechanical, hydraulic, electro-hydraulic, or other type of control device for controlling the operation of the lost motion mechanism 130, i.e., for switching it between its locked and unlocked states, respectively, as described above. For example, the engine controller 120 may be implemented by a microprocessor and corresponding memory storing executable instructions used to implement the necessary control functions, including those described below, as known in the art. It should be understood that other functionally equivalent implementations of the engine controller 130, such as a suitable programmed application-specific integrated circuit (ASIC), may also be employed. Additionally, the engine controller 120 may include peripheral devices intermediate to the engine controller 120 and the lost motion device 130 that enable the engine controller 120 to achieve control over the operating state of the lost motion device 130. For example, if 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 peripheral devices may include suitable solenoids, as known in the art.

[0008] 2 schematically illustrates another embodiment of a conventional valve actuation system 100′ incorporating a lost motion component 230, with like reference numerals referring to like elements as compared to FIG. 1. In this second embodiment, the lost motion component 230 is not housed within one of the valve train components 108, 110, but instead is housed within a fixed member 232, such as a cylinder head or engine block, while still contacting the second valve train component 110. For example, if the second valve train component 110 is an end-pivoting rocker arm or finger follower, the lost motion component 230 may be embodied by a foldable pivot as known in the art.

[0009] Cost, packaging, and size are often factors that can determine the desirability of an engine valve actuation system. In many cases where it is desirable to incorporate one or more lost motion components into a valve train, the ability to include valve train components to accommodate such lost motion components may be limited by various factors, such as lack of space requirements due to their bulky size and / or high cost. Therefore, the provision of a valve actuation system with lost motion components that overcomes these limitations would be a welcome advancement in the art. Summary of the Invention

[0010] This 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 operably 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 operably connected to at least one engine valve to impart valve actuation motion to the at least one engine valve, the second arm further having a second arm contact surface. The separated lost motion device includes a housing having a housing contact surface and a plunger, the plunger being controllable between a first state in which the plunger is maintained rigidly relative to the housing and a second state in which the plunger is capable of reciprocating relative to the housing, the plunger further having an end portion having a plunger contact surface. The housing contact surface is configured to engage with one of the first arm contact surface or the second arm contact surface, and the plunger contact surface is configured to engage with 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 a separated lost motion device between the first arm and the second arm.

[0011] In one embodiment, the housing includes a housing bore extending longitudinally from a first end of the housing, and the plunger is disposed within the housing bore through the first end of the housing. In this embodiment, either the second end of the housing or the end of the plunger includes a lost motion hydraulic passage configured to receive hydraulic fluid for controlling the plunger between the first and second states of the plunger. Furthermore, either the first arm or the second arm includes a hydraulic supply passage configured to align with the lost motion hydraulic passage.

[0012] In one embodiment, the first arm contact surface and the second arm contact surface are configured to allow rotation of the lost motion device 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 may be convex, or the first arm contact surface may be convex and at least one of the housing contact surface or the plunger contact surface may be 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 may be 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, either the first arm or the second arm is configured to pivot about a center. If the first arm is configured to pivot about a center, the first arm may include a first arm pivot, and the second arm may be attached to and configured to pivot about the first arm pivot. Alternatively, if the second arm is configured to pivot about a center, the second arm may include a second arm pivot, and the first arm may be attached to and configured to pivot about the second arm pivot. In yet another alternative, both the first arm and the second arm are configured to pivot about a center.

[0014] In another embodiment, the first arm and the second arm each include an input end and an output end. In this embodiment, the separated lost motion 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 configured to prevent over-rotation of the first arm and the second arm 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 fixed to corresponding ones of the plunger contact surface and the housing contact surface. [Brief explanation of the drawings]

[0017] The foregoing and other features and advantages are discussed in detail in the following non-limiting description of specific embodiments, taken in conjunction with the accompanying drawings.

[0018] [Figure 1] 1 is a schematic diagram of a prior art valve actuation system; [Figure 2] 1 is a schematic diagram of a prior art valve actuation system; [Figure 3] FIG. 1 is a schematic diagram of a valve actuation system including a lost motion component according to the present disclosure. [Figure 4] FIG. 1 illustrates a valve actuation system with a center-pivoting first arm and an end-pivoting valve-side second arm, plus a lost motion component, according to the present disclosure. [Figure 5] FIG. 1 illustrates a valve actuation system with a center-pivoting first arm and an end-pivoting valve-side second arm, plus a lost motion component, according to the present disclosure. [Figure 6] FIG. 1 illustrates a valve actuation system including an end-pivoting cam-side first arm and a center-pivoting second arm, as well as a lost motion component, according to the present disclosure. [Figure 7] FIG. 1 illustrates a valve actuation system including an end-pivoting cam-side first arm and a center-pivoting second arm, as well as a lost motion component, according to the present disclosure. [Figure 8]1 illustrates a valve actuation system including a center-pivoted first arm and a center-pivoted second arm as well as a lost motion component according to the present disclosure. [Figure 9] 1 illustrates a valve actuation system including a center-pivoted first arm and a center-pivoted second arm as well as a lost motion component according to the present disclosure. [Figure 10] 1 illustrates a valve actuation system including a center-pivoted first arm and a center-pivoted second arm as well as a lost motion component according to the present disclosure. [Figure 11] 1 illustrates a valve actuation system including a center-pivoted first arm and a center-pivoted second arm as well as a lost motion component according to the present disclosure. [Figure 12] 10A-10C illustrate an alternative embodiment of a valve actuation system including a center-pivoted first arm and a center-pivoted second arm as well as a lost motion component in accordance with the present disclosure. [Figure 13] 10A-10C illustrate an alternative embodiment of a valve actuation system including a center-pivoted first arm and a center-pivoted second arm as well as a lost motion component in accordance with the present disclosure. [Figure 14] FIG. 1 is a schematic diagram of a valve actuation system according to the present disclosure illustrating the rotation of a lost motion component relative to a first arm and a second arm of the valve actuation system. [Figure 15] FIG. 1 is a schematic diagram of a valve actuation system according to the present disclosure illustrating the rotation of a lost motion component relative to a first arm and a second arm of the valve actuation system. [Figure 16] FIG. 1 is a schematic diagram of a valve actuation system according to the present disclosure illustrating the rotation of a lost motion component relative to a first arm and a second arm of the valve actuation system. [Figure 17] 10 is a side cross-sectional view of a valve actuation system according to the present disclosure, illustrating an alternative configuration of a stop surface according to the present disclosure. [Figure 18]FIG. 10 is a rear cross-sectional view of a valve actuation system according to the present disclosure, illustrating an alternative configuration of a stop surface according to the present disclosure. [Figure 19] 10A-10C illustrate alternative embodiments for providing "carry along" functionality according to the present disclosure. [Figure 20] 10A-10C illustrate alternative embodiments for providing "carry along" functionality according to the present disclosure. [Figure 21] 10A-10C illustrate alternative embodiments for providing "carry along" functionality according to the present disclosure. [Figure 22] 10A-10C illustrate alternative embodiments for providing "carry along" functionality according to the present disclosure. [Figure 23] 10A-10C illustrate alternative embodiments of pivot mechanisms that can minimize clearance between lost motion components and adjacent valve train components in accordance with the present disclosure. [Figure 24] 10A-10C illustrate alternative embodiments of pivot mechanisms that can minimize clearance between lost motion components and adjacent valve train components in accordance with the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0019] As used herein, the term "operably connected" is understood to refer to at least a functional relationship between two components, i.e., that the claimed components must be connected (which may include the presence of an intervening element or elements) to perform the specified function.

[0020] FIG. 3 schematically illustrates one embodiment of a valve actuation system 300 according to the present disclosure incorporating a discrete lost motion component 330, with like reference numerals referring to like elements as compared to FIGS. 1 and 2. As used herein, “discrete” refers to its conventional meaning of constituting a separate entity or part. Thus, in this second embodiment, the discrete lost motion component 330 is not housed or supported within one of the valve train components 108, 110 as in FIG. 1, or within a fixed member 232 as in FIG. 2, but instead is formed as a separate component 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, support for the discrete lost motion component 330 is provided by one or more support joints. As used herein, a support joint is the meeting of two elements that are (i) joined in the sense of being in close association or relationship with one another, including from separable contact to inseparable connection, and (ii) configured to support or hold an isolated lost motion component within a valve train. Additionally, the support joint may provide a degree of freedom for the isolated lost motion component 330 to rotate relative to one or more adjacent valve train components.

[0021] 3, such support joints 340, 341 are shown generally as including contact surfaces 330a, 330b disposed on the lost motion component 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 lost motion component 330 and the corresponding contact surfaces 108a, 110a of the valve train components 108, 110 are complementarily configured to facilitate support of the lost motion component 330 by the valve train components 108, 110 and to smooth operation of the lost motion component 330 despite movement of the valve train components 108, 110. It will therefore be understood that the various complementary contact surfaces described herein are examples of support joints or portions of support joints that may be used to implement the lost motion component 330 (and the various specific embodiments thereof described below).

[0022] Thus, it can be seen that the valve actuation system 300 comprises an isolated lost motion component 330 and adjacent valve train components 108 , 110 that support the isolated lost motion component 330 .

[0023] 3, control of the isolated lost motion 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 various embodiments described below, such control is provided through the use of hydraulic fluid supplied under the control of the engine controller 120. However, as will be appreciated by those skilled in the art, other types of control schemes may likewise be employed for this purpose. In the case of fluid supplied under the control of the engine controller 120, a feature of the present disclosure is that such fluid supply passages pass through at least one of the contact surfaces 108a, 110a, 330a, 330b, various examples of which are further shown and described below.

[0024] While specific implementations of the isolated lost motion component 330 based on specific configurations of sub-components and locking mechanisms are described in more detail below, isolated lost motion components 330 according to the present disclosure are generally characterized as being capable of being controlled between a rigid / unlocked state and a compliant / unlocked state, regardless of the mechanism employed for this purpose, and as being configured to be isolated components supported by adjacent valve train components.

[0025] 4 and 5 illustrate an embodiment of a valve actuation system 400 that can be used to implement the valve actuation system 300 of FIG. 3. As shown, the valve actuation system 400 includes a shaft-mounted first arm 402 and a pivot-mounted valve-side second arm 404, as well as a separate lost motion component 406. As best shown in FIG. 4, 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 configurations are possible as known to those skilled in the art) and a valve bridge 420 and corresponding engine valves 422, 424. In accordance with known techniques, the cam 408 includes one or more cam lobes 412 configured to provide primary and / or auxiliary valve actuation motion to the engine valves 422, 424.

[0026] In this embodiment, the first arm 402 is configured to be attached to a rocker shaft (not shown) via a rocker shaft bore 414 formed in the first arm 402. Additionally, the first arm 402 includes a motion-receiving component 410, in this case in the form of a cam roller, configured to contact a cam 408. Additionally, the first arm 402 includes a boss 430 opposite the motion-receiving component 410, i.e., on the opposite side of the rocker shaft bore 414, that extends toward the engine valves 422, 424. The boss 430 includes a pivot 432 that allows for attachment of the second arm 404 to the pivot 432 and further allows for reciprocating movement of the second arm 404 about the pivot 432. The distal end of the second arm 404 (relative to the first arm 402) includes a swivel or e-foot 426 configured to establish contact with the valve bridge 420.

[0027] It should be noted that although the various embodiments shown and described herein include two engine valves and corresponding valve bridges, it is understood that the valve actuation systems described herein may be applied to single valve systems as well, i.e., systems where no valve bridge is required.

[0028] In certain embodiments, the first arm 402 and second arm 404 are operatively connected to the valve actuation motion source 408 and the valve bridge 420 / valves 422, 424, respectively, but are "half rockers" in that they do not completely cover the distance between the valve actuation motion source 408 and the valve bridge 420 / valves 422, 424, as is the case with "full rockers" known in the art. As explained in more detail below, the first arm 402 and the second arm 404, in combination with the decoupled lost motion component 406 when operating in a locked or motion transmitting state, may operate as an essentially rigid unit such that the valve actuation motion provided by the valve actuation motion source 408 is transmitted to the valve bridge 420 / valves 422, 424, or, when the decoupled lost motion component 406 is controlled to an unlocked state, may operate as a compliant unit in which all (or almost all, as in the case of the "failsafe" lift provided even in the unlocked state) valve actuation motion applied to the decoupled lost motion component 406 results in reciprocating motion of the first arm 402 relative to the second arm 404, thus absorbing such motion relative to the valve bridge 420 / valves 422, 424.

[0029] Referring again to FIG. 4 , the isolated lost motion component 406 is disposed between and supported by the first arm 402 and the second arm 404. The isolated lost motion component 406 includes a housing 440 and a plunger 442 disposed within the housing 440 through a first end of the housing 440. Both the housing 440 and the plunger 442 may be disposed about the longitudinal axis of the lost motion component 406. As used herein, the modifier “isolated” refers to a configuration of the lost motion component 406 in which the lost motion component 406 exists as a separate structure relative to other valve train components, is not surrounded by or contained within other valve train components, but still communicates with other valve train components via support joints for support within the overall valve train. As best shown in FIG. 5 , the plunger 442 is slidably disposed within a housing bore 502 formed in the housing 440.

[0030] 5, 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 that extends out of the housing 440. In certain embodiments, each of the housing contact surfaces 540 and plunger contact surfaces 542, such as contact surfaces 330a, 330b shown in FIG. 3, is configured to mate with a complementary contact surface formed on an adjacent valve train component, i.e., the first arm 402 and the second arm 404. That is, the plunger contact surface 542 and the corresponding contact surface 544 (such as contact surface 108a shown in FIG. 3) on the first arm 402 collectively form one support joint, and the housing contact surface 540 and the corresponding contact surface 546 (such as contact surface 110a shown in FIG. 3) on the second arm 404 collectively form another support joint.

[0031] In the illustrated example, both the housing contact surface 540 and the plunger contact surface 542 are formed as convex surfaces configured to engage corresponding complementary concave surfaces 544, 546 formed on the first arm 402 and the second arm 404, respectively, as described below. However, it should be understood that the convex / concave surfaces shown in FIG. 5 may be reversed, i.e., the housing contact surface 540 and the plunger contact surface 542 may be formed as concave surfaces, and the first arm contact surface 544 and the second arm contact surface 546 may be formed as convex surfaces. Furthermore, the housing contact surface 540 and the plunger contact surface 542 may include a combination of concave and convex surfaces, and the corresponding contact surface 744 of the first arm and the corresponding contact surface 746 of the second arm may also be a combination of complementary convex and concave surfaces. This combination of convex and concave contact surfaces provides a degree of manufacturing “foolproofing” in that it makes it difficult, if not impossible, to incorrectly orient the lost motion component 406 relative to the first arm 602 and the second arm 604. The illustrated embodiment further includes a lost motion hydraulic passage 526 formed in the first end of the plunger 442, and more specifically, the opening of the lost motion hydraulic passage 526 is formed in the plunger contact surface 542. Although the lost motion hydraulic passage 526 is shown as being formed in the plunger 442, it should be understood that such a passage may alternatively be formed in the second end of the housing 440, and more specifically, the opening of the lost motion hydraulic passage 526 may be formed in the housing contact surface 540.

[0032] FIG. 5 also illustrates additional features of the second arm 404. As described above, the second arm 404 is attached to a pivot 432 provided by the first arm 402. The pivot 432 may include a hydraulic passage 531 operably connected to a constant supply of hydraulic fluid (not shown) provided by the rocker shaft. The hydraulic passage 531 may be in fluid communication with an annular channel (not shown) formed in the outer surface of the pivot 432. The annular channel may be aligned with 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 lash screw hydraulic passage 561 formed in a lash screw 560 extending from the end of the second arm distal to the pivot 432. In this manner, lubricating hydraulic fluid is supplied to the swivel 426 in contact with the valve bridge 420. Similarly, the second lubricant supply passage 534 provides lubricating hydraulic fluid to the support joint established by the housing contact surface 540 and the corresponding contact surface 544 provided by the first arm 404.

[0033] As mentioned above, the convex housing contact surface 540 and the plunger contact surface 542 are shown engaged with corresponding concave contact surfaces 544, 546 formed on the first arm 402 and the second arm 404, respectively. When a biasing force is applied to (or by) the lost motion component 406, resulting in contact between the lost motion component 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 lost motion component 406 from becoming disengaged from between the first arm 402 and the second arm 404 due to other forces (e.g., vibration or torque) applied to either the housing 440 or the plunger 442 that are not substantially parallel to the longitudinal axis of the lost motion component 406. While other configurations of complementary contact surfaces 540, 542, 544, 546 may be employed for this purpose, as described below, the illustrated convex and concave surfaces allow rotational movement of either first arm 402 or second arm 404 relative to either housing 440 or plunger 442, so long as the contact surfaces 540, 542, 544, 546 are able to slide relative to one another without losing mating engagement, i.e., operate as a flexible support joint. In one embodiment, any of the respective concave and convex contact surfaces shown and described herein may be formed as spherical contact surfaces.

[0034] As will be appreciated by those skilled in the art, the mating engagement of the contact surfaces 540, 542, 544, 546 helps to facilitate retention of the lost motion component 406 between the first arm 402 and the second arm 404, so long as the contact surfaces 540, 542, 544, 546 are able to remain in close proximity to one another. To ensure such close proximity throughout all operating conditions of the valve actuation system 400 (as well as its assembly during manufacture), it is desirable to prevent the first arm 402 and the second arm 404 from rotating away from one another such that the close proximity between the corresponding contact surfaces 540, 542, 544, 546 could be lost, thereby enabling unintended displacement of the lost motion component 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 configured to engage with the first arm stop surface 550 to prevent over-rotation of the first arm 402 and the second arm 404 relative to one another. In the example shown in FIG. 5 , the first arm stop surface 550 and the second arm stop surface 552 are configured to be in close proximity to one another such that as the second arm 404 rotates about the pivot 432 away from the first arm 402 (clockwise as shown in FIG. 5 ), the first arm stop surface 550 and the second arm stop surface 552 engage with one another, thereby preventing further rotation. Such over-rotation of the first arm 402 away from the second arm 404 can be prevented by selecting the distance between the first arm stop surface 550 and the second arm stop surface 552 such that the distance between them is fully taken up (i.e., the surfaces 550, 552 contact each other) when the first arm 402 reaches the maximum allowable rotation away from the second arm 404.

[0035] 5 , first arm 402 is configured with a first hydraulic passage 520, a second hydraulic passage 522, and a third hydraulic passage 524, where first hydraulic passage 520 is configured to align with a selectable hydraulic fluid supply provided by a rocker arm (not shown) as known in the art, third hydraulic passage 524 is configured to align with a lost motion hydraulic passage 526 formed in plunger 442, and second hydraulic passage 522 provides a connection between first hydraulic passage 520 and third hydraulic passage 524. In one embodiment, the respective diameters of third hydraulic passage 524 and plunger lost motion hydraulic passage 526 are large enough to ensure fluid communication between these hydraulic passages 524, 526 despite rotational movement of first arm 402 relative to plunger 442. As described below, the supply or removal of pressurized hydraulic fluid through hydraulic passages 524, 526 may provide control over the locked and unlocked states of operation of lost motion component 406.

[0036] 5, lost motion component 406 is shown in cross section to better illustrate hydraulically controlled locking mechanism 504, which forms a subassembly of lost motion component 406 and is disposed between housing 440 and plunger 442. As further shown, plunger spring 516 is provided to bias plunger 442 out of housing 440. Locking mechanism 504 shown in FIG. 5 is generally of the type described in U.S. Pat. No. 9,790,824, the teachings of which are incorporated herein by reference and repeated in relevant portions below.

[0037] 5, the locking mechanism 504 includes a plunger 442 disposed within a housing bore 502 formed and extending from a first end of the housing 440 along the longitudinal axis of the lost motion component 406. An inner plunger 510 is slidably disposed within a longitudinal bore 514 formed in the plunger 442. A locking element in the form of a wedge 506 is provided and configured to engage an outer annular recess 508 formed in a surface defining the housing bore 502. The illustrated embodiment is of a normally locked locking mechanism 504, i.e., in this case, no hydraulic control is applied to the inner plunger 510 via the lost motion hydraulic passage 526, the inner plunger spring 512 biases the inner plunger 510 into position, and the wedge 506 contacts the larger diameter portion of the inner plunger 442, thereby extending radially from an opening formed in the plunger 442 and thereby engaging the outer recess 508, effectively locking the plunger 442 in position relative to the housing 440.

[0038] In this locked state, any valve-actuating motion applied to lost motion component 406 (whether primary or secondary) is transmitted by lost motion component 406. Note that despite being in the locked state as shown in FIG. 5, because the longitudinal extent of outer recess 508 is greater than the thickness of wedge 506, a small amount of movement is still possible between plunger 442 and housing 440, as will be explained in more detail below. As shown in FIG. 5, this additional space is occupied, for example, when valve-actuating motion is applied to lost motion component 406, thereby overcoming the outward bias applied to plunger 442 by plunger spring 516.

[0039] Alternatively, if the lost motion component 406 remains locked and unloaded (e.g., during base circle), the bias applied by the plunger spring 516 will cause the plunger 442 to move within its bore 502 as far as the longitudinal extent of the outer recess 508 will allow, i.e., to the left as shown in FIG. 5, until the wedge 506 abuts the leftmost face 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 remain biased into contact with the corresponding contact surfaces 546, 544 of the adjacent arms 402, 404.

[0040] Such biasing force exerted by plunger spring 516 can be selected to further ensure that arms 402, 404 (or additional upstream or downstream valve train components in the system, not shown) are biased continuously into contact with their respective endpoints of the valve train, i.e., the source of valve actuation motion and the engine valve. Furthermore, because outward movement of plunger 442 from within bore 502 is limited by the longitudinal extent of outer recess 508 (when in the locked state), the biasing force exerted by plunger spring 516 on adjacent arms 402, 404 (and, again, any additional upstream or downstream valve train components in the system) does not excessively bias the normal operation of any automatically adjustable compliant components in the valve train, such as hydraulic lash adjusters (HLAs). To this end, it should be understood that other techniques for limiting such movement of plunger 410 relative to housing 402 may be employed, even during the unlocked state of lost motion component 400. Additionally, plunger spring 516 is preferably selected so that the force applied by plunger spring 516 to any of the valve train components, regardless of the locked / unlocked state of locking mechanism 504, does not apply excessive biasing force to compliant valve train components (such as HLA) or engine valve springs.

[0041] 5 , supplying hydraulic fluid sufficiently pressurized to the top of the inner plunger 510 (the left-most face as shown in FIG. 5 ) via the lost motion hydraulic passage 526 to overcome the bias of the inner piston spring 516 moves the inner plunger 510 within the bore 514, allowing the wedge 506 to contact the small radius portion of the inner plunger 510 and retract to disengage from the outer recess 508, thereby effectively unlocking the plunger 442 from the housing 440 and allowing the plunger 442 to slide freely within its bore 502, in this case under the bias provided by the plunger spring 516. In this unlocked state, a valve actuation motion applied to the lost motion component 406 will cause the plunger 442 to reciprocate within its bore 502. In this manner, assuming the movement of plunger 442 within bore 702 is greater than the maximum range of the applied valve actuation motion (i.e., plunger 442 cannot bottom out within bore 502), such valve actuation motion is not transferred by lost motion component 406 and is effectively lost. Alternatively, as previously described, the movement of plunger 442 within bore 502 may be configured so that plunger 442 "bottoms out," i.e., contacts the closed end of bore 502, to always provide a "fail-safe" valve lift in the event that locking mechanism 504 fails.

[0042] As described above, the contact surfaces 540, 542, 544, 546 provided by the lost motion component 406 and the first and second arms 402, 404 are configured to accommodate rotation of the lost motion component 406 relative to either or both of the first and second arms 402, 404. Such rotation, which depends on the operating state of the lost motion component 406, is further illustrated and described highly schematically with reference to FIGS. 14-16. FIGS. 14-16 illustrate a valve actuation system 1400 according to the present disclosure, specifically including a first arm 1402, a second arm 1404, and a lost motion component 1406, which rotates (in this case) about a rocker shaft 1410, as described in accordance with various embodiments herein. As further shown, the lost motion component 1406 comprises a housing 1440 and a plunger 1442, as described herein.

[0043] 14 and 15 show the locking mechanism of the lost motion component 1406 maintained in its locked state, such that the lost motion component 1406 and the first and second arms 1402, 1404 function essentially as a single rigid unit, and valve actuation motion applied by the valve actuation motion source 1416 is transferred from the first arm 1402 to the lost motion component 1406 and then to the second arm 1404. For ease of illustration, the first and second arms 1402, 1404 are shown as having vertical portions 1402a, 1404a extending therefrom, respectively, that provide fixed contact surfaces against corresponding contact surfaces of the housing 1440 and plunger 1442. In this locked state, as shown in FIG. 14, the plunger 1442 extends a length L1 from the housing 1440 and contacts the vertical portion 1402a of the first arm 1402 at an angle θ1. Similarly, the housing 1440 has a substantially constant length L2, including the portion 1440a of the housing 1440 that contacts the second arm 1404, and in this locked state contacts the vertical portion 1404a of the second arm 1404 at an angle θ2. As further shown in FIG. 14, when no valve actuation motion is applied to the first arm 1402 (e.g., the base circle of a cam), no deflection or valve lift is achieved by the second arm 1404.

[0044] The lost motion component 1406 and the first arm 1402 and the second arm 1404 operate as a single unit during this locked state. Thus, the application of the maximum valve operating motion (as shown in FIG. 15) from the valve operating motion source 1416 to the first arm 1402 results in the application of such valve operating motion to the second arm 1404 and the deflection or valve lift D of the second arm 1404. Despite the application of such valve operating motion, the locked state of the lost motion component 1406 ensures that the values of L1, L2, θ1, and θ2 remain essentially the same, and as a result, there is little or no rotation of the plunger 1442 or the housings 1440, 1440a with respect to each of the first arm 1402 or the second arm 1404.

[0045] In contrast, FIG. 16 shows a state in which the locking mechanism of the lost motion component 1406 is maintained in its unlocked state, and the lost motion component 1406 absorbs the valve operating motion applied to the first arm 1402 through the plunger 1442 and the first arm 1402, so that the valve operating motion is not transmitted to the second arm 1404. This is shown in FIG. 16 by the absence of any deflection or valve lift in the second arm 1404. However, the angles θ1', θ2' at which the plunger 1442 and the housings 1440, 1440a contact the first arm 1402 and the second arm 1404, respectively, during this unlocked state, and the length L1' of the plunger 1442 extending from the housing 1440, as shown in FIG. 16, are changed compared to the unlocked state during the application of the maximum valve operating motion. More specifically, the application of the maximum valve operating motion results in rotation of the lost motion component 1406, as evidenced by L1' < L1, and θ1' < θ1 and θ2' < θ2. However, again here, such rotation of the lost motion component 1406 is smoothed by the configuration of each contact surface as described herein.

[0046] Figures 6 and 7, where like reference numbers represent like elements, illustrate an alternative embodiment of a valve actuation system 600 that can be used as the valve actuation system 300 shown in Figure 3. The valve actuation system 600 includes a pivot-mounted cam-side first arm 602 and a shaft-mounted second arm 604, as well as a lost motion component 406. Similar to the system 400 shown in Figures 4 and 5, the valve actuation system 600 is operatively connected to a valve actuation motion source 408 (e.g., a cam) and a valve bridge 420 and corresponding engine valves 422, 424.

[0047] In this embodiment, the second arm 604 is configured to be attached to a rocker shaft (not shown) via a rocker shaft bore 614 formed in the second arm 604. A distal end of the second arm 604 (away from the rocker shaft bore 614) includes a swivel or e-foot 426 configured to establish contact with the valve bridge 420. Additionally, the second arm 604 includes a boss 630 opposite the swivel or e-foot 426, i.e., on the opposite side of the rocker shaft bore 614, that extends toward the valve actuation motion source 408. The boss 630 includes a pivot 632 that allows attachment of the first arm 602 to the pivot 632 and allows reciprocating motion of the first arm 602 about the pivot 632. Additionally, the first arm 602 includes a motion-receiving component 610, in this case in the form of a cam roller, configured to contact the cam 408.

[0048] 4 and 5, the first arm 602 and the second arm 604 are “half rockers.” Thus, again, the first arm 602 and the second arm 604, in combination with the lost motion component 406, may operate as an essentially rigid unit such that valve actuation motion provided by the valve actuation motion source 408 is transferred to the valve bridge 420 / valves 422, 424, or, if the lost motion component 406 is controlled to an unlocked state, may operate as a compliant unit in which any valve actuation motion applied to the lost motion component 406 results in reciprocating motion of the first arm 602 relative to the second arm 604, thus absorbing such motion relative to the valve bridge 420 / valves 422, 424.

[0049] As previously discussed and best shown in FIG. 7 , each of the housing contact surface 540 and the plunger contact surface 542 is configured to mate with a complementary contact surface formed on an adjacent valve train component, i.e., the first arm 602 and the second arm 604. In the illustrated example, both the housing contact surface 540 and the plunger contact surface 542 are formed as convex surfaces configured to engage corresponding complementary concave surfaces 744, 746 formed on the first arm 602 and the second arm 604, respectively. However, it should be understood that the convex / concave surfaces shown in FIG. 7 may be reversed, i.e., the housing contact surface 540 and the plunger contact surface 542 may be formed as concave surfaces, and the first arm contact surface 744 and the second arm contact surface 746 may be formed as convex surfaces. Furthermore, the housing contact surface 540 and the plunger contact surface 542 may include a combination of concave and convex surfaces, and the corresponding contact surfaces 744 and 746 on the first and second arms are also combinations of complementary convex and concave surfaces. This combination of convex and concave contact surfaces provides a degree of manufacturing “foolproofing” in that it is difficult, if not impossible, to incorrectly orient the lost motion component 406 relative to the first and second arms 602 and 604.

[0050] As shown in FIGS. 6 and 7 , the first arm 602 is attached to a pivot 632 provided by the second arm 604. The pivot 632 may include a hydraulic passage 731 operably connected to a selectable supply of hydraulic fluid (not shown) provided by the rocker shaft. As shown in FIG. 7 , the hydraulic passage 731 is in fluid communication with a lubrication passage 770 that provides lubricating hydraulic fluid to the motion-receiving component 610. The hydraulic passage 731 may additionally be in fluid communication with an annular channel (not shown) formed in the outer surface of the pivot 632. The first arm 602 is further configured with a first hydraulic passage 722 in fluid communication with a second hydraulic passage 724, as shown in FIG. 7 . The annular channel formed in the pivot 632 may be aligned and in fluid communication with the first hydraulic passage 722. The second hydraulic passage 724, in turn, is configured to align with the lost motion hydraulic passage 526 formed in the plunger 442. In this case, the respective diameters of the second hydraulic passage 724 and the plunger lost motion hydraulic passage 526 are large enough to ensure fluid communication between these hydraulic passages 724, 526 despite rotational movement of the first arm 402 relative to the plunger 442. As previously mentioned, the supply or removal of pressurized hydraulic fluid through the hydraulic passages 722, 724, 526 may provide control over the locked and unlocked states of operation of the lost motion component 406.

[0051] 7, a first lubricant supply passage 732 is formed in the second arm 604, which 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 of hydraulic fluid (not shown) provided by the rocker shaft and is also in fluid communication with a lash screw hydraulic passage 561 formed in a lash screw 560 extending from the end of the second arm distal to the pivot 432. In this manner, lubricating hydraulic fluid is supplied to the swivel 426 in contact with the valve bridge 420. Similarly, the second lubricant supply passage 734 provides lubricating hydraulic fluid to the joint established by the housing contact surface 540 and a corresponding contact surface 746 provided by the second arm 604.

[0052] 4 and 5, stop surfaces may be provided to prevent over-rotation of the first arm 602 and second arm 604. This is shown in Figure 7, where 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.

[0053] Figures 8-11, where like reference numbers represent like elements, illustrate another alternative embodiment, a valve actuation system 800 that can be used as the valve actuation system 300 shown in Figure 3. Valve actuation system 800 includes a lost motion component 406, as well as a shaft-mounted first arm 802, and a shaft-mounted second arm 804 is shown. Similar to systems 400, 600 shown in Figures 4-7, valve actuation system 800 is operatively connected to a valve actuation motion source 408 (e.g., a cam) and a valve bridge 420 and corresponding engine valves 422, 424.

[0054] As mentioned above, in this embodiment, the first arm 802 and the second arm 804 are each configured to be attached to a rocker shaft (not shown) via respective rocker shaft bores 814, 816 formed in the first arm 802 and the second arm 804. In this embodiment, the distal end of the first arm 802 (away from its rocker shaft bore 816) includes a motion-receiving component 810, in this case in the form of a cam roller, configured to contact the cam 408. The distal end of the second arm 804 (away from its rocker shaft bore 814) includes a swivel or e-foot 426 configured to establish contact with the valve bridge 420.

[0055] 4-7, the first arm 802 and the second arm 804 are "half rockers." Thus, again, the first arm 802 and the second arm 804, in combination with the lost motion component 406, may operate as an essentially rigid unit such that valve actuation motion provided by the valve actuation motion source 408 is transmitted to the valve bridge 420 / valves 422, 424, or, if the lost motion component 406 is controlled to an unlocked state, may operate as a compliant unit in which all (or, again, nearly all, as in a "fail-safe" configuration) valve actuation motion applied to the lost motion component 406 results in reciprocating motion of the first arm 802 relative to the second arm 804, thus absorbing such motion relative to the valve bridge 420 / valves 422, 424.

[0056] FIG. 9 shows a top view of the system 800 with the lost motion component 406 removed to better illustrate the relationship of the first arm 802 and the second arm 804 to one another. Specifically, the first arm 802 and the second arm 804 each have respective overlapping portions 902, 904, in which respective rocker shaft bores 816, 814 (shown in hidden lines) are formed. As shown, the respective widths of the first arm 802 and the second arm 804 at the overlapping portions 902, 904 (from top to bottom as shown in FIG. 9 ) are less than the respective maximum widths of the first arm 802 and the second arm 804. In this manner, when the first arm 802 and the second arm 804 are positioned adjacent to one another on the rocker shaft, the lost motion component 406 (also not shown in FIG. 9 ) can simply be maintained in substantial linear alignment with the valve actuation motion source 408 and the engine valves 422, 424. Additionally, the overall width of the system 800 can be minimized (again, when the first arm 802 and the second arm 804 are positioned adjacent to one another on the rocker shaft), thereby conserving space that is often limited along the rocker shaft. This configuration of the overlapping portions 902, 904 is not a requirement; for example, the width of the overlapping portions 902, 904 can be substantially equal to or greater than the width of the remainder of the first arm 802 and the second arm 804.

[0057] Figure 10 shows a cross-sectional view taken along section line XX of Figure 9. In this view, the portion of the first arm 802 adjacent the valve actuation motion source 408 and supporting the motion receiving component 810 is shown in cross-section, as is a portion of the housing 440 of the lost motion component 406. In addition, the second arm 804 is also shown in cross-section, thereby revealing a portion of the lubrication hydraulic passage 1032 (the remainder of which is shown in hidden lines) that provides fluid communication from a constant hydraulic fluid supply in the rocker shaft (not shown) to the lash screw hydraulic passage 561 in the lash screw 560, as described above.

[0058] 11 shows a cross-sectional view taken along section line XI-XI of FIG. 9 . In this view, a first hydraulic passage 1122 and a second hydraulic passage 1124 are formed in the first arm 802, where the first hydraulic passage 1122 is configured to receive hydraulic fluid from a selectable (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 lost motion hydraulic passage 526. As previously mentioned, the diameters of the second hydraulic passage 1124 and the lost motion hydraulic passage 526 may be selected to maintain alignment with one another despite rotation of the plunger 442 relative to the first arm 802. As previously mentioned, the supply or removal of pressurized hydraulic fluid through the hydraulic passages 1122, 1124, 526 may provide control of locked and unlocked states of operation of the lost motion component 406.

[0059] Again, each of the housing contact surface 540 and the plunger contact surface 542 is configured to mate with a complementary contact surface formed on the adjacent valve train component, i.e., the first arm 802 and the second arm 804. In the illustrated example, both the housing contact surface 540 and the plunger contact surface 542 are formed as convex surfaces configured to engage with corresponding complementary concave surfaces 1144, 1146 formed on the first arm 802 and the second arm 804, respectively. However, it should be understood that the convex / concave surfaces shown in FIG. 11 may be reversed, i.e., the housing contact surface 540 and the plunger contact surface 542 may be formed as concave surfaces and the first arm contact surface 1144 and the second arm contact surface 1146 may be formed as convex surfaces, or a combination of convex / concave surfaces may be employed to prevent manufacturing errors as discussed above.

[0060] It should be noted that the embodiment shown in Figures 8-11 does not include stop surfaces as described above in connection with Figures 5 and 7. Thus, such stop surfaces are not a requirement of the present disclosure and may instead be provided as a function of a particular application.

[0061] Similar to the embodiment of Figures 8-11, Figures 12 and 13 illustrate an alternative embodiment of a valve actuation system 1200 that can be used as the valve actuation system 300 shown in Figure 3. The valve actuation system 1200 includes a center-pivoted first (or input) arm 1202 and a center-pivoted second (or output) arm 1204 in accordance with the present disclosure, as well as a lost motion component 1206. However, unlike the embodiment of Figures 8-11, in which the first arm 802 and the second arm 804 are configured to reside adjacent to each other on a rocker arm, the second arm 1204 includes two sides 1270, 1272 that are configured such that the first arm 1202 is nested between the sides 1270, 1272. As previously mentioned, the first arm 1202 and the second arm 1204 each include a rocker shaft bore 1216, 1214 formed therein and configured to receive a rocker shaft (not shown). In this case, the rocker shaft bore 1214 formed in the second arm 1204 includes two axially aligned openings, one on each of two side surfaces 1270, 1272. As previously mentioned, the first arm 1202 includes a motion-receiving component 1210, which, in the illustrated embodiment, may take the form of a cam roller configured to contact a source of valve-actuating motion (not shown). A particular feature of the embodiment of FIGS. 12 and 13 is that the first arm 1202 and the second arm 1204 are configured such that the first arm 1202 receives valve-actuating motion from an overhead cam (not shown).

[0062] Similar to the previous embodiments described above, valve actuation system 1200 includes a decoupled lost motion component 1206 located between and supported by a first arm 1202 and a second arm 1204. In this case, however, as best shown in Figure 13, decoupled lost motion component 1206 is oriented substantially vertically, as opposed to the substantially horizontal orientation of the decoupled lost motion component shown and described above with respect to Figures 4-11.

[0063] As best shown in FIG. 13 , the first arm 1202 has an input end 1390 and an output end 1392 that face each other about the rocker shaft bores 1214, 1216, while the second arm 1204 has an input end 1394 and an output end 1396 that face each other about the rocker shaft bores 1214, 1216. In addition, a separate lost motion component 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 that each end 1390-1396 has in transmitting the valve actuation motion applied thereto. That is, an input end 1390 of the first arm 1202 receives valve actuation motion from a valve actuation motion source (not shown), such as an overhead cam, while an output end 1392 of the first arm 1202 transfers (or outputs) that valve actuation motion to the isolated lost motion device 1206. Meanwhile, an input end 1394 of the second arm 1204 receives valve actuation motion (if provided) from the isolated lost motion device 1206, while an output end 1396 of the second arm 1204 transfers (or, again, outputs) the valve actuation motion applied to the second arm 1204 to one or more engine valves and / or additional valve train components (not shown).

[0064] 13 , consistent with the above-described embodiments, the lost motion component 1206 similarly includes a housing 1330 and a plunger 1334 that implement a locking mechanism 1300. However, in this case, the functionality of the plunger spring 516 described above is implemented by a plunger spring 1316 disposed on the exterior of the housing 1330 and plunger 1334. In the illustrated embodiment, the plunger spring 1316 is disposed between a flange 1382 formed on or attached to the exterior surface of the plunger 1334 and a shoulder 1384 formed on the housing 1330, as shown. As further shown in FIG. 13 , the lost motion component 1206 also includes a locking mechanism 1300 comprising an inner plunger 1310 (slidably disposed with a longitudinal bore 1314 formed in the plunger 1334), a locking element or wedge 1306, and an annular channel 1308. 5 and 7, i.e., under the control of hydraulic fluid supplied by a hydraulic passage 1326 formed in the plunger 1334. Furthermore, in this case, the housing 1330 is not formed as a unitary component but instead has an end cap 1331 attached to the housing 1330, which in this embodiment is implemented substantially as a tube having a second end closed by the end cap 1301. In this embodiment, the housing contact surface 1340 is formed in the end cap 1301. Although not fully shown in FIG. 13, the hydraulic passage 1336 formed in the first arm 1202 is in fluid communication with a selectable hydraulic fluid supply provided by a rocker shaft (not shown) and is further in fluid communication with the hydraulic passage 1326 formed in the plunger 1334.

[0065] 13 also shows contact surfaces 1344, 1346 configured to engage corresponding housing and plunger contact surfaces 1340, 1342. However, in this case, the housing contact surface 1340 is formed as a convex surface (in keeping with the embodiment of FIGS. 4-11 ) configured to mate with a corresponding concave contact surface 1346 of a lash screw 1380 forming part of the second arm 1204, while the plunger contact surface 1342 is formed as a concave surface configured to mate with a corresponding convex surface 1344 of the first arm 1202. As discussed above, this opposite configuration of the housing and plunger contact surfaces 1340, 1342 effectively avoids the chance of installing the lost motion component 1206 incorrectly, i.e., upside down relative to the orientation shown in FIGS. 12 and 13 .

[0066] Finally, similar to the previous embodiment, stop surfaces may be provided to prevent over-rotation of the first arm 1202 and 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 configured to engage the first arm stop surface 1250.

[0067] An alternative implementation of such a stop surface is shown in Figures 17 and 18, which depict a system 1700 that can be used as the valve actuation system 300 of Figure 3. The valve actuation system 1700 includes a first arm 1702 and a second arm 1704 that are substantially similar to the first arm 1202 and second arm 1204 shown in Figures 12 and 13, except that the first arm 1702 and second arm 1204 include stop surfaces 1750, 1752. In this embodiment, the first stop surface 1750 is formed as a downwardly facing, radially extending surface (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 upwardly facing, radially extending surface of the second arm 1704 away from the motion-imparting portion 1704a of the second arm 1704. 17 , the first stop surface 1750 and the second stop surface 1752 are configured to be aligned opposite one another such that clockwise rotation of the first arm 1702 separates the first stop surface 1750 and the second stop surface 1752 from one another, while clockwise rotation of the second arm 1704 moves the first stop surface 1750 and the second stop surface 1752 toward one another until they eventually contact one another. Upon such contact, further clockwise rotation of the second arm 1704 causes the first arm 1702 to be “carried” along with the second arm 1704 in the clockwise direction. In this manner, the gap between the first arm 1702 and the second arm 1704, where a separate lost motion component (not shown) is present, must not exceed a predetermined length, thereby preventing the gap from exceeding the maximum length of the lost motion component, which could otherwise cause the lost motion component to become dislodged from the system.

[0068] In addition to the ability to be switched between locked and unlocked states, the discrete lost motion components described herein may be configured with a travel limiting feature that prevents the discrete lost motion component from exceeding a maximum overall length. For example, in the context of the housing and plunger embodiment described above, such a travel limiting feature would prevent the plunger from extending past a maximum distance from its housing bore. Various examples of such travel limiting features are taught in co-pending U.S. application entitled "DISCRETE LOST MOTION DEVICE" and having attorney docket number JVSPP110US, the teachings of which are incorporated herein.

[0069] While such travel limiting features in a separated lost motion component are advantageous, they can create further problems in certain systems, for example, and referring to Figures 17 and 18, where the spacing between the first arm 1702 and the second arm 1704 on which the separated lost motion component is supported can exceed the maximum length of the separated lost motion component (defined by its travel limiting features). In this case, without the above-mentioned "carry" feature provided by the first stop surface 1750 and the second stop surface 1752, the separated lost motion component could lose its support from the first arm 1702 and the second arm 1704 and become dislodged.

[0070] Given the availability of such movement-limiting features in separate lost motion components, various alternative embodiments may be provided in which the "carry" features of Figures 17 and 18 may be implemented. Figures 19-22 illustrate such alternative embodiments.

[0071] 19 illustrates one embodiment of a system 1900 comprising a first arm 1902 and a second arm 1904 and a schematically illustrated constrained lost motion component 1906 interposed therebetween as described above. However, in this implementation, the lost motion component 1906 is rotatably secured to the first arm 1902 and the second arm 1904 via an arrangement such as clevis pins 1960, 1962 and corresponding retainer clips or cotter pins 1961, 1963. Specifically, the clevis pins 1960, 1962 pass through openings formed in both the first arm 1902 and the second arm 1904 that align with corresponding openings formed in the respective ends of the lost motion component 1906. Preferably, the clevis pins 1960, 1962 fit loosely within such openings such that the lost motion component 1906 remains fixed to the first arm 1902 and second arm 1904 but is still free to rotate about the clevis pins 1960, 1962. As a result, the travel limit of the lost motion component 1906 resists any tendency for the first arm 1902 and second arm 1904 to rotate away from each other such that the gap between them (in which the lost motion component 1906 is disposed) would increase beyond the maximum length of the lost motion component 1906.

[0072] 20 illustrates one embodiment of a system 2000 comprising a first arm 2002 and a second arm 2004 and a schematically illustrated constrained lost motion component 2006 interposed therebetween as described above. However, in this implementation, the lost motion component 2006 is rotationally fixed to the first arm 2002 and the second arm 2004 by a constrained ball-and-cup (convex and concave) configuration. Specifically, in the illustrated embodiment, the lost motion component 2006 is provided with a spherical ball or knob 2060, 2064 at each end, while the first arm 2002 and the second arm 2004 are provided with corresponding spherical cups 2061, 2065. Once the balls 2060, 2064 are positioned within the cups 2061, 2065, suitable retainer clips 2062, 2066 may be disposed between the balls 2060, 2064 and the cups 2061, 2065, thereby retaining the balls 2060, 2064 within the cups 2061, 2065. Thus, again, separation between the first arm 2002 and the second arm 2004 is prevented insofar as the first arm 2002 and the second arm 2004 are rotatably attached to the limited travel lost motion component 2006.

[0073] 21 illustrates an embodiment of a system 2100 that is substantially identical to the system 2000 illustrated in FIG. 20 , except that the cups are formed with threaded inserts 2160, 2162 that are configured to mate with complementary threaded portions of the first arm 2102 and the second arm 2104. In this embodiment, a ball-and-cup joint as described above can be first established with the respective threaded inserts 2160, 2162, which can then be mated with the corresponding threaded portions of the first arm 2160 and the second arm 2104. The threaded fit between the inserts 2160, 2162 and the first arm 2102 and the second arm 2104, in addition to making assembly of the system 2100 easier, also allows for relatively fine adjustments to be made to the system 2100, for example, for lash purposes.

[0074] 22 illustrates one embodiment of a system 2200 including a first arm 2202 and a second arm 2204 and a schematically illustrated constrained lost motion component 2206 interposed therebetween as described above. In this implementation, the first arm 2202 and the second arm 2204 include openings 2203, 2205 configured to receive extensions 2262, 2264 formed on opposite ends of the lost motion component 2206. In turn, the extensions 2262, 2264 each include a threaded end 2265, 2267 configured to receive a respective jam nut 2263, 2266, thereby coupling or rotatably securing the lost motion component 2206 to the first arm 2202 and the second arm 2204.

[0075] As will be appreciated by those skilled in the art, due to normal valve actuation motion, etc., various ones of the embodiments shown in Figures 19-22 may cause a temporary gap or space to form between the lost motion component and the hydraulic passage (e.g., hydraulic passage 524 shown in Figure 5) that supplies hydraulic fluid to the lost motion component as well as the lost motion component as a control input. Such a gap can result in a loss of hydraulic fluid, which can lead to reduced hydraulic pressure to the lost motion component. As a result, the lost motion component may not be able to reliably switch between its locked and unlocked states, which can result in reduced engine performance or even engine damage.

[0076] To prevent this loss of hydraulic connectivity, FIG. 23 illustrates a pivot connection that may prevent such a gap from occurring. As shown in FIG. 23 , an outer sleeve 2302 (which may be integral with a valve train component, such as a rocker arm, configured to supply hydraulic fluid (oil supply) to a lost motion component, or may be an insert into the valve train 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 disposed between a surface of the bore 2362 and a recessed annular portion 2306 of the piston 2360, allowing the piston 2360 to slide within the bore 2362 but preventing it from extending beyond a predetermined distance. Meanwhile, movement of the piston 2360 into the bore 2362 is limited by contact of a shoulder surface 2364 of the piston 2360 with an upper surface 2366 of the outer sleeve 2302.

[0077] As shown, piston 2360 has a hydraulic passage 2324 formed therein that communicates with both the top and bottom of piston 2360; i.e., hydraulic fluid can pass from the bottom to the top of piston 2360 via hydraulic passage 2324. Additionally, as shown in the lower right corner of FIG. 23 , a supply port 2308 provides fluid communication between a hydraulic fluid source (not shown) and a bore 2362 adjacent the bottom end of piston 2360. Preferably, the shoulder surface 2364 and top surface 2366, mentioned above, are configured such that when these surfaces contact one another, supply port 2308 remains unobstructed by piston 2360, such that hydraulic fluid supplied by supply port 2308 can still flow within bore 2362.

[0078] When hydraulic fluid is supplied to bore 2362 via supply port 2308, the presence of pressurized fluid below piston 2360 tends to bias piston 2360 upward (as shown in FIG. 23 ) in addition to allowing fluid to flow within hydraulic passage 2324. As a result, this upward bias on piston 2360 tends to prevent the formation of a gap between contact surface 2342 of piston 2360 and a corresponding contact surface (not shown) on the lost motion component. In effect, piston 2360 acts like a hydraulic lash adjuster (without the check valves typically incorporated in hydraulic lash adjusters) to maintain fluid communication between the lost motion component and adjacent valve train components that supply hydraulic fluid thereto.

[0079] FIG. 24 illustrates an alternative mechanism for preventing loss of hydraulic connectivity similar to that shown in FIG. 23. Specifically, a sliding piston 2460 is disposed within a bore 2462 formed in a valve train component, such as a rocker arm. In this case, a hydraulic supply passage 2470 communicates (via a fluid connection, not shown) with a hydraulic passage 2424 formed in the piston 2460, which again supplies hydraulic fluid to the adjacent lost motion component. In this case, however, the upward bias of the piston 2460 is provided by a spring 2480, as shown. Thus, the bias exerted by the spring is not dependent on the presence of hydraulic fluid supplied to the piston 2460, but instead is constantly supplied. The travel limit in this embodiment is provided by a screw 2482 secured to the bottom end of the piston 2460 to prevent excessive force from the spring 2480 from being applied to the valve train in which it resides (and potentially interfering with the operation of any in-line hydraulic lash adjusters).

[0080] As will be appreciated by those skilled in the art, other types of travel limiting mechanisms or configurations may be employed similar to the embodiment shown in FIGS.

Claims

1. 1. A valve actuation system for actuating at least one engine valve in an internal combustion engine, comprising: a first arm operatively connected to a valve actuation motion source for receiving valve actuation motion from the valve actuation motion source, the first arm having a first arm contact surface; a second arm operatively connected to the at least one engine valve for imparting a valve actuation motion to the at least one engine valve, the second arm having a second arm contact surface; A separate lost motion device, a housing having a housing contact surface; a plunger controllable between a first state in which the plunger is maintained rigidly relative to the housing and a second state in which the plunger is capable of reciprocating relative to the housing, the plunger further comprising 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; A valve actuation system, 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 separated lost motion device between the first arm and the second arm.

2. the housing includes a housing bore extending longitudinally into the housing from a first end thereof, the plunger being disposed within the housing bore through the first end of the housing; 2. The valve actuation system of claim 1, wherein either the second end of the housing or the end of the plunger includes a lost motion hydraulic passage configured to receive hydraulic fluid for controlling the plunger between its first and second states, and either the first arm or the second arm includes a hydraulic supply passage configured to be aligned with the lost motion hydraulic passage.

3. 2. The valve actuation system of claim 1, wherein the first arm contact surface and the second arm contact surface are configured to allow rotation of the lost motion device relative to the first arm and the second arm.

4. 4. The valve actuation system of 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. 4. The valve actuation system of 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. 4. The valve actuation system of 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. 4. The valve actuation system of 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 of claim 1 , wherein the first arm is configured to pivot about a center.

9. 9. The valve actuation system of claim 8, wherein the first arm comprises a first arm pivot, and the second arm is attached to the first arm pivot and configured to pivot about the first arm pivot.

10. The valve actuation system of claim 8 , wherein the second arm is configured to pivot about a center.

11. 2. The valve actuation system of claim 1, wherein the second arm is configured to pivot centrally, further comprising a second arm pivot, the first arm being attached to the second arm pivot and configured to pivot about the second arm pivot.

12. The valve actuation system of claim 1 , wherein the first arm and the second arm are both configured to pivot about a center.

13. each of the first arm and the second arm having an input end and an output end; 13. The valve actuation system of claim 12, wherein the separated lost motion component 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 comprising the first arm contact surface, and the input end of the second arm comprising the second arm contact surface.

14. 2. The valve actuation system of claim 1, wherein 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 configured to prevent over-rotation of the first arm and the second arm away from each other.

15. 2. The valve actuation system of claim 1, wherein the first arm contact surface and the second arm contact surface are configured to be rotatably fixed to corresponding ones of the plunger contact surface and the housing contact surface.

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