Valve bridge restraint and guide and related methods

Abstract

The valve bridge system includes constraints and guides to manage bridge jumps and other uncontrolled valve bridge motions during engine operation. The constraints may include an e-foot collar, an extension on the bridge, and a bridge brake pin. The guides may include a deflection surface on the bridge extension as well as a valve stem tip lead-in chamfer that surrounds the valve bridge valve pocket. The method of configuring the valve bridge may include configuring the valve step tip lead-in chamfer based on a worst case position of the valve bridge defined by one or more or a combination of the constraints provided by the e-foot collar, the extension, and the brake pin.

Description

[Technical Field]

[0001] The present disclosure relates generally to valve actuation systems in internal combustion engines, and more particularly to a valve bridge system with restraints and guides for managing bridge jump and other uncontrolled valve bridge motion during engine operation. The restraints may include an e-foot collar, an extension with a lower guide surface on the bridge, and a bridge brake pin. The guides may include a deflection surface on the bridge extension, as well as a valve stem tip lead-in chamfer surrounding the valve bridge valve pocket. The present disclosure also generally relates to a method for configuring a valve bridge with restraints and guides. [Background technology]

[0002] Valve actuation systems for use in internal combustion engines are well known in the art. Such valve actuation systems typically include a valve train with one or more components that transfer valve actuation motion from a valve actuation motion source (e.g., one or more cams) to the engine valves. FIG. 1 illustrates a typical exhaust valve actuation subsystem in a prior art valve actuation system having a lost motion valve bridge 600 / 700. It should be understood that similar components may be used to implement intake valve actuation. A main exhaust rocker arm 100 / 400 may be pivotally mounted and adapted to rotate about a rocker shaft 110. A motion follower 120 may be disposed at one end of the main exhaust rocker arm 100 / 400 and may contact and follow a motion source (i.e., a rotating cam 260) to impart motion to the rocker. The cam 260 may be controlled by a controller 265 and may include a single main exhaust bump 262 (or a main intake bump in the case of an intake valve actuation system). As is well known in the art, actuating fluid may be supplied to the rocker arms 100 / 400 from an actuating fluid supply under the control of a solenoid hydraulic control valve (not shown). The actuating fluid may flow through a passage 510 formed in the rocker shaft 110 to a hydraulic passage 215 formed in the rocker arms 100 / 400. A return or auxiliary passage 520 may also be formed in the rocker shaft.

[0003] Continuing to refer to FIG. 1 , a swivel foot, also commonly referred to as an elephant foot or e-foot 240, can be part of a screw assembly 230 disposed at one end of the rocker arm 100 / 400 and transfers motion from the rocker arm 100 / 400 to a valve bridge 710 that spans two or more engine valves 810 / 890 and 820 / 920 associated with a given cylinder. Often, such a valve bridge allows another component of the valve train (e.g., a rocker arm) to simultaneously actuate the engine valves that engage the valve bridge through a brake pin 650 / 700 disposed in a bore 714. The position of the swivel foot 240 relative to the rocker arm 100 / 400 can be adjusted using an adjustment screw 232 secured by a threaded fastener 234, thereby providing adjustment for lash (i.e., the space between the swivel foot 240 and the valve bridge 710). A hydraulic passage 235 communicating with the rocker passage 215 may be formed in the screw 232 to convey fluid from the rocker passage 215 to the valve bridge. A swivel foot 240 may contact the lost motion valve bridge 600 / 700. The exhaust valve bridge 600 / 700 may include a valve bridge body 710 having a central opening 712 extending through the valve bridge and a side opening 714 extending through a first end of the valve bridge. The side opening 714 may receive a sliding pin 650 that contacts the valve stem of the first exhaust valve 810. The valve stem of the second exhaust valve 820 may contact the other end of the exhaust valve bridge.

[0004] Ideally, during operation, the opposing forces exerted by the motion-transmitting component (such as a rocker arm) and the engine valve spring ensure that the valve bridge remains in contact (allowing for normal lash settings) simultaneously with the motion-transmitting component and the engine valve. In this way, the valve bridge consistently remains aligned with the engine valve and is positioned to transmit valve-actuation motion to the engine valve. As used herein, this state of the valve bridge is referred to as the "controlled state" of the valve bridge relative to the engine valve.

[0005] Some valve actuation systems are configured to provide so-called auxiliary valve actuation motion, i.e., valve actuation motion other than or in addition to that used to operate the engine in a positive power-producing mode through the combustion of fuel. In such valve actuation systems, valve train components (e.g., tappets, push rods, rocker arms, valve bridges, etc.) may be configured to include devices or lost motion assemblies that allow valve actuation motion to be transmitted through the valve train components to the engine valves, or to be selectively “lost” if such motion is not transmitted through the valve train components to the engine valves. Signals to activate or deactivate the lost motion assembly, thereby causing it to absorb or transmit motion, may be provided via hydraulic (hydraulic) pressure controlled by an upstream solenoid valve. FIG. 1 illustrates an example of such a system, described in U.S. Patent Application Publication No. 2012 / 0024260, the teachings of which are incorporated herein by reference. In this case, the valve bridge assembly 600 / 700 includes a lost motion assembly in the form of a locking mechanism. The central opening 712 of the exhaust valve bridge 600 may receive a lost motion or locking assembly including an outer plunger 720 disposed in an outer plunger bore 722, a cap 730 disposed on the outer plunger 720, an inner plunger 760, an inner plunger spring 744, an outer plunger spring 746, and one or more wedge rollers or balls 740. The swivel foot 240 engages the cap 730, thus transferring motion to the outer plunger 720 and ultimately to the bridge 600 and valve when the outer plunger 720 is locked relative to the bridge 600. In the illustrated embodiment, the locking mechanism ball 740 may be located within an inner plunger recess 762 and may pass through an opening in the outer plunger 720 and engage with a recess 770 formed in the body of the valve bridge upon upward movement of the inner plunger 760.In this state, the ball 740 is prevented from disengaging from the recess 770 due to the outer diameter of the inner plunger 760, thereby locking the outer plunger 720 in a fixed relationship relative to the valve bridge 710. As a result, any valve actuation motion applied to the outer plunger 720 by the rocker arm 100 / 400 is transmitted to the valve bridge 710 and the engine valves 810 / 910, 820 / 920. However, when the recess formed in the inner plunger 760 aligns with the ball 740, the ball can disengage from the recess 770 in the valve bridge 710, thereby unlocking the outer plunger 720 and allowing it to reciprocate relative to the valve bridge 710. In this state, any valve actuation motion applied to the outer plunger 720 moves the outer plunger within the valve bridge 710 and is not transmitted to the engine valves. Another valve bridge based locking / unlocking system is disclosed in U.S. Patent Application Publication No. 2014 / 0326212, the teachings of which are incorporated herein by reference.

[0006] However, in systems of the type illustrated in FIG. 1, the possibility exists for the locking mechanism to partially engage, particularly in operating environments where the valve bridge is reciprocating at high speeds and under high loads. Partial engagement can occur, for example, when the inner plunger or latch piston in prior art systems such as those described above disengages from its ball or wedge element. In this case, slippage of the locking mechanism can occur during rapid changes in load and high-speed oscillations of the bridge and other valve train components during engine operation. Partial engagement and slippage of the locking mechanism can occur after the normal valve actuation motion (i.e., valve opening motion) is initially applied to the engine valve by the bridge. Slippage after such initial motion can result in a rapid release of valve spring energy when one or both of the engine valves are suddenly closed against their respective valve seats. When this occurs, the force provided by the valve actuation components to open the engine valve is suddenly removed, allowing the engine valve to rapidly accelerate to a closed position without being restrained under the considerable force of the valve spring. When an engine valve reaches a fully closed position (i.e., stops against a valve seat formed in the cylinder head), the momentum of the valve bridge can cause the valve bridge to "jump" off the valve stem tip. That is, the valve bridge continues to move in an uncontrolled manner, generally away from and / or out of alignment with one or both of the engine valve stems. Such movement can create the potential for a collision between the valve bridge and a rocker arm or other component within the valve train or engine cylinder head environment. In extreme situations, the valve bridge can completely jump off one or both of the valve stem tips and remain disengaged from the engine valve, thereby causing engine failure and / or damage. Uncontrolled valve bridge conditions are also known to occur as a result of overspeed operation of an internal combustion engine.This type of movement of the valve bridge into a position where the stability or operation of the system is compromised is referred to herein as "uncontrolled movement," and as used herein, this condition of the valve bridge in a position where the stability or operation of the system is compromised is referred to as an "uncontrolled condition" of the valve bridge relative to the engine valve.

[0007] Given the potential for valve bridge jumping, misalignment, and the associated deleterious effects on engine and valve actuation system operation and wear in prior art systems, a solution that prevents, minimizes, accommodates, or guides against uncontrolled valve bridge conditions or positions (regardless of cause) would represent a welcome addition to the art. Summary of the Invention

[0008] According to one aspect of the present disclosure, the valve bridge may include restraints and guides to control and manage variations in valve bridge motion during engine operation. Restraints contemplated by the present disclosure include an e-foot collar adapted to surround the e-foot and an extension on the valve bridge adapted to fit between the valve springs. Guides contemplated by the present disclosure include a lead-in chamfer that surrounds the valve pocket on the valve bridge to guide the valve tip into the valve pocket when the valve bridge becomes misaligned, and a deflection surface on the extension to prevent the extension from catching on sharp corners or other features within the valve bridge environment. The disclosed restraint and guide features prevent bridge jump or other bridge motion that would otherwise be uncontrolled, thus maintaining the valve bridge in a controlled state throughout engine operation.

[0009] According to one aspect, the present disclosure provides a valve bridge for use with an engine valve assembly of an internal combustion engine, the engine valve assembly including a plurality of engine valves, the internal combustion engine having a valve train for transferring motion from a motion source to the valve bridge, the valve train including an e-foot adapted to engage the valve bridge, the valve bridge including a central bridge housing and a locking assembly disposed within the central bridge housing and having an e-foot engagement surface, the locking assembly adapted to selectively lock or enable movement of the e-foot engagement surface relative to the central bridge housing, thereby transferring or absorbing motion, the bridge further including a control surface disposed in contact with the e-foot that would otherwise move the bridge to an uncontrolled state, thereby maintaining the bridge in a controlled state throughout engine operation. According to a further aspect, the control surface may be circular and may be defined by a collar that may completely or partially surround the e-foot engagement surface on the bridge. According to a further aspect, the e-foot engagement surface may be on a plunger or piston assembly disposed within the central bridge housing. According to a further aspect, the control surface may extend a sufficient distance from the central bridge housing to constrain movement of the valve bridge relative to the e-foot to maintain the bridge in a controlled state. According to a further aspect, the control surface may extend a sufficient distance from the central bridge housing to limit movement of the valve bridge through a maximum controlled displacement. According to a further aspect, the valve bridge may include a valve pocket defining a valve stem seat for receiving a valve stem tip, and a lead-in surface adapted to guide the valve stem seat into alignment with the valve stem tip, whereby the bridge would otherwise move to an uncontrolled position. According to another aspect, the lead-in surface may be a chamfer. According to a further aspect, the lead-in surface may extend a sufficient distance from the valve seat to guide the valve stem seat into alignment, whereby maximum bridge jump displacement would otherwise occur.According to a further aspect, an extension having at least one lower guide surface may be disposed adjacent to the central bridge housing and may have at least one lower guide control surface configured to limit bridge movement by engaging a valve spring assembly including a valve spring and a valve spring retainer, which may be oversized, to maintain the bridge in a controlled state. According to a further aspect, the valve bridge may include a brake pin disposed within the brake pin bore to further constrain valve bridge movement. Furthermore, according to one aspect, the disclosed constraining e-foot collar and extension provide a constraint against, and thus define, a worst-case deviation in bridge position, and this worst-case position can be used to configure a guide surface, such as a lead-in chamfer, to ensure that the lead-in chamfer captures and guides the valve bridge back to an aligned, controlled position against all possible erroneous movement. Thus, the valve bridge is maintained in a controlled position, preventing jumps and erroneous, uncontrolled movement of the valve bridge.

[0010] According to one aspect, the valve bridge includes an e-foot collar having a control surface surrounding the e-foot, thereby constraining movement (translation, pitch, roll, or yaw) of the valve bridge relative to the e-foot. According to one aspect, a valve bridge for use with an engine valve assembly of an internal combustion engine, the engine valve assembly including a plurality of engine valves, the internal combustion engine having a valve train for transferring motion from a motion source to the valve bridge, the valve train including an e-foot adapted to engage the valve bridge, the valve bridge may include a central bridge housing and a locking assembly disposed within the central bridge housing and having an e-foot engagement surface, the locking assembly adapted to selectively lock or allow movement of the e-foot engagement surface relative to the central bridge housing, thereby transferring or absorbing motion, the bridge further including a control surface disposed in contact with the e-foot that would otherwise cause the bridge to move in an uncontrolled state, the control surface thereby maintaining the bridge in a controlled state throughout engine operation.

[0011] According to another aspect, the valve bridge may include an extension on the bridge that defines one or more control surfaces positioned and adapted to engage the valve spring and / or valve spring retainer when the valve bridge position deflects from the controlled state, thereby restraining movement of the valve bridge.

[0012] According to another aspect, the valve bridge can include a valve stem tip lead-in chamfer surrounding the valve pocket, the lead-in chamfer configured to capture the valve stem tip at all possible positions of the valve bridge relative to the valve stem tip, as defined by the constraint of the e-foot collar control surface and / or the extension control surface.

[0013] According to another aspect, the bridge brake pin may provide additional restraint to bridge motion in combination with the restraint of the e-foot collar. This configuration may be further combined with the restraint of the extension, the valve bridge valve pocket surrounding the valve lead-in surface, and / or the deflection surface on the bridge extension, each feature used alone or in combination with one or more of the other features.

[0014] According to another aspect, the bridge extension may include a deflection feature to prevent the bridge extension from catching on sharp corners or surfaces in the overhead engine environment during engine operation.

[0015] According to another aspect, a method for configuring a valve bridge control surface includes assessing extreme positions of a valve bridge in both locked and unlocked states, configuring an e-collar to constrain movement of the bridge, optionally configuring an extension control surface to constrain movement of the bridge, and optionally configuring a valve tip lead-in chamfer based on the constraints defined by the e-collar and / or extension. [Brief explanation of the drawings]

[0016] 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. [Figure 1] 1 is a cross-sectional illustrative view of a valve actuation system including a valve bridge with a locking mechanism according to the prior art; [Figure 2] FIG. 10 is a lower front perspective view of a valve bridge according to the present disclosure; [Figure 3] FIG. 10 is a top front perspective view of a valve bridge according to the present disclosure; [Figure 4] FIG. 4 is a bottom view of the valve bridge of FIGS. 2 and 3. [Figure 5] FIG. 5 is a cross-sectional view of the valve bridge (along section line 5-5 of FIG. 3) showing the valve bridge in a partially flipped up position. [Figure 6]FIG. 6 is a perspective view of the valve bridge of FIGS. 2 to 5, arranged in an internal combustion engine and in a controlled state. [Figure 7] FIG. 7 is a perspective view of the valve bridge of FIGS. 2 to 6 positioned in an internal combustion engine and in an uncontrolled state in which the bridge is separated from the valve tip. [Figure 8A] 8A-8C are cross-sectional views of the valve bridge of FIGS. 2-7 illustrating a bridge jump condition or sequence of events. [Figure 8B] 8A-8C are cross-sectional views of the valve bridge of FIGS. 2-7 illustrating a bridge jump condition or sequence of events. [Figure 8C] 8A-8C are cross-sectional views of the valve bridge of FIGS. 2-7 illustrating a bridge jump condition or sequence of events. [Figure 9] FIG. 9 is a partial cross-sectional view (along line 9-9 of FIG. 3) of the valve bridge with the valve bridge at its peak jump height. [Figure 10A] 10A-10C illustrate, in partial cross-section, the sequence in which a valve tip lead-in chamfer according to the present disclosure maintains a valve bridge in a controlled state. [Figure 10B] 10A-10C illustrate, in partial cross-section, the sequence in which a valve tip lead-in chamfer according to the present disclosure maintains a valve bridge in a controlled state. [Figure 10C] 10A-10C illustrate, in partial cross-section, the sequence in which a valve tip lead-in chamfer according to the present disclosure maintains a valve bridge in a controlled state. [Figure 10D] 10A-10C illustrate, in partial cross-section, the sequence in which a valve tip lead-in chamfer according to the present disclosure maintains a valve bridge in a controlled state. [Figure 11] 10A-10C are schematic diagrams of lead-in chamfer configurations and exemplary bridge constraint geometries in accordance with the present disclosure; [Figure 12] 1 illustrates a cutaway view of a brake pin and e-foot collar restraint arrangement according to aspects of the present disclosure. [Figure 13] 1 illustrates an exemplary method or process for configuring a valve bridge control surface according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0017] 2-6, a valve bridge 200 according to the present disclosure includes a guide feature in the form of a collar or vertically extending wall 202 adapted to interface with and control movement of the valve bridge 200 relative to an e-foot on a rocker arm. With particular reference to FIG. 6, an e-foot (also called a swivel foot) 204 of a rocker arm 206 is adapted to engage the valve bridge 200 when the valve bridge 200 is placed (i.e., installed) in an engine environment. The collar 202 may extend upward from a body portion 220, which may have a central bridge housing that houses components of a bridge locking or folding mechanism 250. The collar 202 may define a control surface 203 therein to constrain movement of the valve bridge 200 relative to the e-foot 204, thereby preventing uncontrolled movement of the valve bridge relative to the e-foot. The collar 202 may include one or more flat areas on its outer surface to provide clearance and / or restraint of movement of the valve bridge relative to other engine components in an overhead environment (FIG. 6). The collar 202 and control surface 203 can completely surround the e-foot engagement surface 252, which can be disposed on the cap 254 of the lock assembly or mechanism 250 in a manner similar to the cap 730 described in the context of FIG. 1 . As will be appreciated, variations on the continuous surface shown in this example, such as an interrupted or discontinuous surface extending upward to surround the e-foot engagement surface, are contemplated by the present disclosure. For example, the collar need not be a complete, continuous, circular feature. There may be interrupted walls with slots or spaces between them, forming several control surfaces surrounding the e-foot. The slots or spaces can be dimensioned to prevent the e-foot from passing laterally through the slots or spaces.

[0018] FIG. 3 illustrates an isometric top front view of an exemplary bridge 200. FIG. 3 also illustrates a three-dimensional reference space defined by three axes—a longitudinal axis 10 extending through the locking mechanism (center of the central bridge housing) and the valve stem pocket; a lateral axis 20 extending through the locking mechanism orthogonal to the longitudinal axis 10; and a vertical axis 30 extending orthogonal to both the longitudinal axis 10 and the lateral axis 20—that is useful for understanding bridge motion in the context of the present disclosure. This reference space provides a frame of reference for describing various bridge motions that the restraint features of the present disclosure may limit or accommodate. As will be appreciated from the present disclosure, bridge jump and the corresponding tendency of the bridge to move toward an uncontrolled state may involve one or more of translation, rotation, pitch, roll, or yaw about one or more of these three axes. For example, a bridge jump may involve translating the valve bridge 200 upward along a vertical axis, as well as pitching the valve bridge 200 relative to the longitudinal axis (i.e., the pitch elevates one valve step pocket higher than the other valve stem pocket), and rolling about the longitudinal axis (i.e., the roll causes the valve bridge to rotate about the longitudinal axis). In accordance with the present disclosure, valve bridge movement may be constrained to prevent or accommodate any one or combination of these movements to the extent that the valve bridge is maintained in a controlled state, in other words, preventing the valve bridge from moving to an otherwise uncontrolled state.

[0019] As shown in FIG. 6 , the vertical extent or height of the collar 202 may be configured to provide that, during controlled movement of the valve bridge 200 as shown in FIG. 6 , the bottom e-foot 204 is positioned above the terminal edge 209 of the control surface 203 when the locking mechanism is locked in place and at its maximum height or stroke relative to the valve bridge main body portion 220. Such a configuration may, for example, facilitate easy installation and removal of the bridge 200. Furthermore, the vertical extent or height of the collar 202 is such that the e-foot 204 can translate into the space defined by the collar 202 and the control surface 203 during a collapsed or unlocked state of a locking assembly or mechanism 250 included in the valve bridge 200. The control surface 203 is also sized (i.e., has a sufficiently large diameter) to be disengaged from engagement with the e-foot during normal, controlled movement of the valve bridge 200. However, the control surface 203 is also sized (i.e., has a sufficiently small diameter) to provide for engagement of the control surface 203 with the e-foot 204 when the valve bridge moves toward an uncontrolled position relative to the e-foot. That is, during movement, such as horizontal or vertical translation, pitch, roll, or yaw, of the valve bridge toward an uncontrolled state or position relative to the e-foot, the collar 202 may operate to surround and contact the e-foot 204 (regardless of the folded / unfolded or locked / unlocked state of the folding mechanism), thereby limiting any translation or other movement of the valve bridge 200 and maintaining the valve bridge 200 in a controlled state. This is illustrated in FIG. 7 , where movement of the valve bridge toward an uncontrolled position or state causes, for example, the valve bridge to move out of contact with the engine valve stem 602. However, as shown in both Figures 6 and 7, the collar 202 is configured to have sufficient vertical range to contact the e-foot 204 and otherwise cause the valve bridge to move into an uncontrolled state or position relative to the e-foot, thereby reducing any tilt or misalignment of the valve bridge.

[0020] According to another aspect of the present disclosure, as shown in Figures 6 and 7, the valve bridge 200 may include an additional guide mechanism in the form of an extension portion 208 (Figure 2) having a control surface 283 and configured to extend between but adjacent the engine valve springs 302 and / or engine valve spring retainers 304. Examples of various embodiments of such extension portions are described in U.S. Patent Nos. 10,883,392, 11,053,819, and 11,319,842, the disclosures and subject matter of which are incorporated herein by reference in their entireties. As described in these documents, the extension portion 208 is configured to remain out of contact with the valve springs 302 and / or retainers 304 during controlled operation of the valve bridge 200, but to contact the valve springs 302 and / or retainers 304 when the valve bridge moves toward an uncontrolled position, thereby limiting tilt / rotation or other undesired movement of the valve bridge 200 toward the uncontrolled state. Extension portion 208 may be provided with a tapered and / or conical deflection surface 281 (FIGS. 2 and 3) at its end. This feature prevents bridge extension portion 208 from catching on corners or other sharp features in the overhead environment (i.e., adjacent the space between valve springs where extension portion 208 is typically located) when bridge 200 undergoes a jump or movement toward an uncontrolled position. Deflecting surface 281 thus prevents uncontrolled positioning of bridge 200 and guides bridge 200 back to a controlled position when it deviates from a controlled state or position.

[0021] FIGS. 8A-8C illustrate a valve bridge jump sequence for a valve bridge having the described guide features. In FIG. 8A, the bridge 200 is in a controlled position relative to the valve stem tips 602, with each valve stem tip 602 aligned with and seated within a valve tip pocket 212. The bridge's locking mechanism is now locked in an extended position relative to the bridge 200. FIG. 8B shows the beginning of a bridge jump condition, where the bridge 200 disengages from the valve stem tips 602. This can occur if there is slippage in the locking mechanism due to partial engagement of the locking mechanism's locking elements. As a result, and due to valve spring force, the valve stem tips 602 can suddenly jump upward as the valves slam shut against their respective valve seats. Such action can cause the valve bridge to pop upward, potentially disengaging from the valve tips. FIG. 8C shows the full range of possible bridge jumps, reaching an upper limit when the locking mechanism collapses to its internal limit within the valve bridge's central housing. FIG. 9 is another cross-sectional view showing the location of the e-foot within the collar at peak jump height.

[0022] As will be appreciated, while the illustrated bridge jump is a pure upward translation, involving the valve tip pockets 212 being equidistant from their respective valve stem tips 602, it will be appreciated from this disclosure that the restraint and guide features described herein can mitigate or accommodate (guide) other undesirable bridge motion, such as pitch of the valve bridge 200 relative to the longitudinal axis, where one of the valve tip pockets 212 is farther from its respective valve stem tip 602 than the other valve pocket 212. Thus, the collar 202 and control surface 203 limit the pitch of the valve bridge relative to the longitudinal axis, such that the control surface 203 encounters the e-foot before the bridge pitches to an uncontrolled position. The collar 202 and control surface 203 are also configured to prevent roll of the valve bridge 200 relative to its longitudinal axis. As will be appreciated, such motion can also be viewed as a pitch of the valve bridge 200 relative to its lateral axis.

[0023] According to aspects of the present disclosure, the valve bridge may also include guide features that accommodate movement toward an uncontrolled state or position (relative to the valve tip) and guide the valve bridge back to a controlled state or position (relative to the valve tip). Referring again to FIGS. 2-9 and 10A-10D, the valve bridge 200 may include control surfaces in the form of lead-in chamfers 210 that substantially surround the valve tip pockets 212. Each lead-in chamfer 210 is configured and adapted to receive a respective engine valve stem 602 and guide the valve stem 602 back into the valve pocket upon misalignment or movement of the valve bridge toward an uncontrolled position relative to one or both of the valve stems 602. FIGS. 10A-10D illustrate, in cross-section, the sequence in which a jumped valve bridge 200 is guided back to a controlled state. The lead-in chamfer 210 in each valve tip pocket 212 is large enough to align with the outer diameter of the tip of the valve stem 602 during worst-case deviations of the valve bridge 200 from its controlled position (i.e., one or more or a combination of translation, pitch, roll, and yaw). The lead-in chamfer 210 is configured to guide the valve bridge 200 back onto one or both of the valve tips after a bridge jump, misalignment, or other event that tends to move the valve bridge toward an uncontrolled position. Starting with FIG. 10A , the valve bridge 200 is moving toward an uncontrolled state as a result of the valve tip pocket 212 losing contact with the valve stem tip 602. Furthermore, the valve tip pocket 212 can also become misaligned with the valve stem tip 602 due to bridge translation or yaw (about a vertical axis), as also shown in FIG. 10A . As can be appreciated, the valve bridge 200 can also experience roll or pitch.According to aspects of the present disclosure, as also shown in FIG. 10A , the bridge 200 is constrained against excessive translation (i.e., along the lateral and longitudinal axes) and excessive roll (about the longitudinal axis) by the collar 202 contacting the e-foot 204, thereby limiting errant, uncontrolled movement of the valve bridge 200. This constraint also limits misalignment of the valve tip pocket 212 relative to the valve stem tip 602. In FIG. 10B , the valve bridge 200 may move into position contacting the valve stem tip 602 (e.g., rotation of the rocker arm 206 and / or stroking or locking of the locking mechanism) urging the valve bridge 200 toward the engine valve). In this example, the lead-in chamfer 210 contacts the outer edge of the valve stem tip 602. As shown in FIGS. 10C and 10D , the angled configuration of the lead-in chamfer 210, combined with continuous contact between the outer diameter of the valve stem tip 602, urges the valve bridge 200 to rotate / translate or otherwise return to a position where the valve tip pocket 212 is aligned with the valve stem tip 602.

[0024] FIG. 11 is a schematic diagram showing a geometric representation of a bottom view of an exemplary lead-in chamfer 210 configuration superimposed on a representation of the valve spring perimeter 620 and a representation of a cross section of an exemplary valve bridge extension 208 having a control surface 283. According to aspects of the present disclosure, the dimensions of the valve bridge lead-in chamfer, such as the diameter of the lead-in chamfer edge circle 211, can be configured to accommodate a determined maximum movement of the valve bridge relative to the valve stem tip. According to aspects of the present disclosure, this determined maximum movement can be defined by the constraint provided by the control surface 203 on the collar 202 and / or the control surface on the extension 208. In this example, the maximum yaw of the extension 208 (about a vertical axis extending into the page) is determined based on the point at which the extension 208 engages the perimeter of the valve spring 620, or in an alternative constraint configuration, the point at which the extension 208 engages the valve spring retainer (304 in FIG. 6) if the valve spring retainer is fabricated with a larger perimeter than the spring perimeter. The extent (in this case, diameter) of the lead-in chamfer 210 may be selected to accommodate this maximum movement and may include allowance for additional clearance 213. Thus, according to aspects of the present disclosure, the maximum (worst-case) movement (translation about the longitudinal, lateral, and vertical axes, pitch, roll, yaw) of the valve bridge 200 relative to the valve stem tip 602 may be defined based on the constraints described above, i.e., the collar control surface and the extension control surface(s). The lead-in chamfer(s) may then be configured to accommodate the determined maximum movement, with some allowance for variation. In other words, the lead-in chamfer is configured to be large enough to capture and guide the valve stem tip at all possible positions of the bridge relative to the valve stem tip, as defined by the constraint features on the valve bridge, i.e., the extension control surface(s) 283 and / or the collar control surface 203. In this manner, the valve bridge can be readily configured to prevent bridge jump and uncontrolled movement.

[0025] While the embodiment of the valve bridge 200 shown in Figures 2-6 and described herein shows a combination of a collar 202, an extension 208, and a lead-in chamfer 210, it is understood that not all three of these features need be included in all implementations of a valve bridge according to the present disclosure. That is, rather than combining all three of these features, the collar 202 can be implemented as a single feature or in combination with either the extension 208 or the lead-in chamfer 210. Furthermore, while these three features are illustrated in the context of a valve bridge that includes a folding mechanism, it is noted that this is not a requirement. That is, it is understood that these features (again, individually, collectively, or in subcombinations thereof) may equally be employed in a valve bridge that does not incorporate a folding mechanism.

[0026] FIG. 12 illustrates another restraint configuration according to aspects of the present disclosure. In this example, a bridge brake pin 280 can be used in conjunction with a collar 203 to provide additional restraint against bridge movement. The bridge brake pin 280 can have a first diameter portion 282 that extends through the bore 270 and is configured to engage the brake piston assembly 400. A brake pin base 284 can have a larger diameter than the first diameter portion 282 and can be disposed within a counterbore 290 in the bridge. The dimensions of the brake pin base 284 and first diameter portion 282, as well as the dimensions of the bore 270 and counterbore 290, can be configured to provide a determined restraint against movement of the valve bridge 200 during braking or other events. As will be appreciated, the brake pin feature can provide restraint against translation and yaw (about a vertical axis) that augments the restraint against movement provided by the collar 203, thereby providing improved control of valve bridge movement and preventing bridge jump and uncontrolled movement during engine operation.

[0027] FIG. 13 illustrates a process 1300 for configuring a bridge restraint and guide according to the present disclosure. At 1302, the locked bridge position (relative to the valve stem tip) at the cam base circle is evaluated. At 1304, the locked bridge position at peak cam lift is evaluated. At 1306, the fully folded bridge position is evaluated. At 1308, the e-foot collar control surface(s) are configured to restrain bridge movement in a controlled state. At 1310, the extension control surface is configured. At 1312, the valve tip introduction control surface (guide) is configured based on the worst-case bridge movement determined based on the evaluation in steps 1302-1310. At 1314, non-interference of the bridge control surface with other components in the overhead environment during normal engine operation can be verified.

[0028] While the present implementation has been described with reference to certain exemplary embodiments, it will be apparent that various modifications and changes can be made to these embodiments without departing from the broader spirit and scope of the invention as set forth in the claims. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.

Claims

1. 1. A valve bridge for use with an engine valve assembly of an internal combustion engine, the engine valve assembly comprising a plurality of engine valves, the internal combustion engine having a valve train for transferring motion from a motion source to the valve bridge, the valve train including a swivel adapted to engage the valve bridge, the valve bridge comprising: A central bridge housing; a locking assembly disposed within the central bridge housing, the locking assembly having a swivel engagement surface, the locking assembly adapted to selectively lock or allow movement of the swivel engagement surface relative to the central bridge housing, thereby transferring or absorbing movement; the valve bridge further comprising a control surface configured to be disengaged from engagement with the swivel during a controlled state of the valve bridge and configured to contact the swivel during an uncontrolled state of the valve bridge.

2. The valve bridge of claim 1 , wherein the control surface completely surrounds the swivel engagement surface.

3. The valve bridge of claim 1 , wherein the control surface is defined by a collar extending around the swivel engagement surface.

4. The valve bridge of claim 3 , wherein the collar is circular.

5. The valve bridge of claim 1 , wherein the swivel engagement surface is on a plunger or piston assembly disposed within the central bridge housing.

6. 2. The valve bridge of claim 1, wherein the control surface extends a sufficient distance from the central bridge housing to constrain movement of the valve bridge relative to the swivel when the valve bridge is in the uncontrolled state.

7. 2. The valve bridge of claim 1, wherein the swivel engagement surface is on a plunger adapted to travel a stroke length within the valve bridge in an unlocked state, and the control surface extends a distance sufficient to limit movement of the valve bridge relative to the swivel throughout the stroke length.

8. 2. The valve bridge of claim 1, further comprising a valve pocket for receiving a valve stem tip, the valve pocket defining a valve stem seat, the valve pocket further comprising a lead-in surface adapted to guide the valve stem seat into alignment with the valve stem tip.

9. The valve bridge of claim 8 , wherein the lead-in surface is a chamfer.

10. 9. The valve bridge of claim 8, wherein the lead-in surface is configured to prevent maximum displacement between the valve stem seat and the valve stem tip.

11. 2. The valve bridge of claim 1, further comprising an extension portion disposed proximate the central bridge housing, the extension portion having at least one lower guide control surface configured to engage a valve spring assembly to limit movement of the valve bridge when the valve bridge is in the uncontrolled state.

12. The valve bridge of claim 11 , wherein the lower guide control surface is configured to engage a valve spring.

13. The valve bridge of claim 11 , wherein the lower guide control surface is configured to engage an oversized valve spring retainer.

14. 12. The valve bridge of claim 11, wherein the lower guide control surface is configured to avoid contact with the valve spring assembly when the valve bridge is in the controlled state, and the lower guide control surface is configured to contact the valve spring assembly to retain the valve bridge when the valve bridge is in the uncontrolled state.

15. 10. The valve bridge of claim 1, further comprising a brake pin configured to contact at least one engine valve of the plurality of engine valves, the brake pin being disposed within a brake pin bore of the valve bridge.

16. 16. The valve bridge of claim 15, wherein dimensions of the brake pin and brake pin bore are configured to constrain relative movement between the brake pin and the valve bridge to prevent uncontrolled movement of the valve bridge.

17. 16. The valve bridge of claim 15, wherein the valve bridge further comprises a brake pin base receptacle for receiving a base of the brake pin, the brake pin base receptacle and the base of the brake pin having dimensions configured to prevent uncontrolled movement of the valve bridge.

18. 10. The valve bridge of claim 1, further comprising a valve pocket lead-in chamfer configured to capture a valve tip at all valve bridge positions within a range of travel of the valve bridge defined by the control surface.

19. 2. The valve bridge of claim 1, wherein the valve bridge has extension portions adapted to engage valve springs associated with the plurality of engine valves and control surfaces on the extension portions that define a range of travel of the valve bridge relative to at least two valve springs, and further comprises valve pocket lead-in chamfers configured to capture valve tips at all valve bridge positions within the range of travel of the valve bridge defined by the control surfaces on the extension portions.

20. 10. The valve bridge of claim 1, further comprising a brake pin adapted to restrain movement of the valve bridge, and further comprising a lead-in surface for guiding the valve bridge relative to a valve stem.

21. 21. The valve bridge of claim 20, wherein the control surface is provided on a collar adapted to at least partially surround and constrain movement of the valve bridge relative to the swivel.

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