Valve bridge system for resisting uncontrolled movement of a valve bridge

Abstract

To provide valve bridge systems that prevent, minimize or accommodate uncontrolled states of valve bridges.SOLUTION: A valve bridge system comprises a valve bridge body configured to extend between at least two engine valves of an internal combustion engine. The valve bridge body comprises a through-bore configured to align with a first engine valve and to receive a bridge pin. A bridge pin boss has the through-bore formed therein, has a longitudinal length, and terminates in an upper surface. The longitudinal length is configured such that the upper surface of the bridge pin boss contacts a surface of the auxiliary rocker arm to resist uncontrolled movement of the valve bridge when the valve bridge is in an uncontrolled state relative to the at least two engine valves.SELECTED DRAWING: Figure 24

Description

Technical Field

[0001] The present disclosure generally relates to a valve actuation system for an internal combustion engine, and more particularly to a valve bridge system including a valve bridge guide used in conjunction with such a valve actuation system.

Background Art

[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 having one or more components for transmitting valve actuation motion from a valve actuation motion source (e.g., one or more cams) to an engine valve. A commonly seen component in the valve train is a so-called valve bridge that includes a device spanning two or more engine valves associated with a given cylinder. In many cases, such a valve bridge enables another component of the valve train (e.g., a rocker arm) to simultaneously actuate two further engine valves that engage the valve bridge. Ideally, during operation, the counteraction of forces applied by the motion transmission component (such as a rocker arm) and the engine valve spring ensures that the valve bridge remains in contact (allowing for normal lash settings) with the motion transmission component and the engine valve at the same time. In this way, the valve bridge consistently maintains an aligned state with the engine valve and is positioned to transmit the 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 with respect to the engine valve.

[0003] Some valve actuation systems are configured to provide a valve actuation motion, other than or in addition to the valve actuation motion used to operate the engine in a positive power generation mode through combustion of fuel, so-called auxiliary valve actuation motion. In such a valve actuation system, the valve bridge may include a device or lost motion assembly that allows the valve actuation motion to be transmitted to the engine valve through the valve bridge, or may be configured to selectively "lose" such motion if it is not transmitted to the engine valve through the valve bridge. FIG. 1 illustrates such a system as 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 710 includes a lost motion assembly in the form of a locking mechanism. In the illustrated embodiment, the locking mechanism includes a ball 740 that can be pushed through an opening in the outer plunger 720 and engage a recess 770 formed in the body of the valve bridge. 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 to the valve bridge 710. As a result, any valve actuation motion applied to the outer plunger 720 by the rocker arms 200 / 400 is transmitted to the valve bridge 710 and the engine valves 810 / 910, 820 / 920. However, when a recess formed in the inner plunger 760 is aligned with the ball 740, the ball can disengage from the recess 770 of the valve bridge 710, thereby releasing the lock on 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 lock / lock release system is disclosed in U.S. Patent Application Publication No. 2014 / 0326212, the teachings of which are incorporated herein by reference.

[0004] However, in a system of the type illustrated in FIG. 1, there is a possibility of partial engagement of the locking mechanism. In this case, a valve actuation movement is first applied to the engine valve, thereby enabling the engine valve to be lifted from the valve seat. However, due to the partial engagement of the locking mechanism and an increase in load or vibration in the valve actuation system, the locking mechanism quickly switches from a partially locked state to an unlocked state. When this occurs, the force provided by the valve actuation movement to open the engine valve is suddenly removed, and under the considerable force of the valve spring, the engine valve can rapidly accelerate to the closed position without being restricted. When the engine valve reaches the fully closed position (i.e., stops against the valve seat formed in the cylinder head), due to the momentum applied to the valve bridge, the valve bridge can continue to move along an uncontrolled trajectory generally away from the engine valve until it hits the rocker arm or some other object. In fact, it is possible for the valve bridge to disengage from the tip of either of the engine valves, resulting in the valve bridge falling off the engine valve and thereby causing engine damage. This type of movement is referred to as "uncontrolled movement" of the valve bridge, and when used herein, this state of the valve bridge is referred to as an "uncontrolled state" of the valve bridge with respect to the engine valve. It is also known that an uncontrolled state of the valve bridge occurs as a result of overspeed operation of an internal combustion engine.

[0005] Considering this potential for malfunction, a solution to prevent, minimize, or accommodate the uncontrolled state of the valve bridge (regardless of the cause) represents a welcome addition to the art. SUMMARY OF THE INVENTION

[0006] The present disclosure describes a valve bridge system that overcomes the above problems of prior art valve bridge systems. In a first main embodiment, the valve bridge system comprises a valve bridge configured to extend between at least two engine valves of an internal combustion engine. A valve bridge guide is operably connected to the valve bridge and comprises a valve bridge control surface for selectively contacting at least one of the valve bridge or the engine valve assembly (comprising at least two engine valves, at least two valve springs corresponding to the at least two engine valves, and at least two spring retainers corresponding to the at least two engine valves). In this embodiment, the valve bridge guide may extend from a formable polymer. The valve bridge control surface is configured to avoid contact with the valve bridge or the engine valve assembly when the valve bridge is in a controlled state with respect to the at least two engine valves, and is further configured to contact the valve bridge or the engine valve assembly and resist the uncontrolled movement of the valve bridge when the valve bridge is in an uncontrolled state with respect to the at least two engine valves. In one embodiment, the valve bridge guide is configured to extend between at least two valve springs, and the valve bridge control surface is at least one concave surface corresponding to at least one convex surface defined by the at least two valve springs or at least two spring retainers or a convex surface defined by a part of the valve bridge. More specifically, each of the at least one concave surface may be defined by both edges such that a line intersecting both edges forms a secant line with respect to the outer diameter of the corresponding one of the at least two valve springs or at least two spring retainers.

[0007] The valve bridge guide and the valve bridge can form an integral structure, or the valve bridge guide can comprise one or more separate components operably connected to the valve bridge. In one embodiment, the valve bridge guide comprises two guide members configured to engage opposite sides of the valve bridge, and may further comprise at least one fastener for operably coupling the two guide members together. The valve bridge guide can comprise an opening for receiving at least a portion of the valve bridge, and can further comprise at least two protruding members, each of the at least two protruding members protruding from the valve bridge guide towards the valve bridge and extending beyond at least the lower surface of the valve bridge facing at least two engine valves. Further, the at least two protruding members can define a valve bridge control surface. Alternatively, each of the at least two protruding members can comprise an attachment surface for engaging a corresponding surface of the valve bridge.

[0008] In a second main embodiment, the valve bridge system can comprise a valve bridge configured to extend between at least two engine valves of an internal combustion engine, the valve bridge comprising a lower surface facing at least two engine valves and an upper surface opposite the lower surface. The system of this main embodiment further comprises a valve bridge guide having a first member maintained in a first fixed position relative to the valve bridge, the first member comprising a first surface facing the upper surface of the valve bridge and at a predetermined distance from the upper surface of the valve bridge when at least two engine valves are in a closed state. The predetermined distance is configured to prevent contact between the first surface and the upper surface of the valve bridge when the upper bridge body is in a controlled state relative to at least two engine valves, and to allow contact between the first surface and the upper surface of the valve bridge when the valve bridge is in an uncontrolled state relative to at least two engine valves to resist the uncontrolled movement of the valve bridge. If the valve bridge comprises a receptacle for receiving the tip of one of the at least two engine valves, the predetermined distance can be shorter than the depth of the receptacle.

[0009] The first fixed position of the first member may be aligned with a first engine valve of at least two engine valves, the first engine valve being the farthest from the rocker shaft of the internal combustion engine. The valve bridge system may further include a second member maintained at a second fixed position relative to the valve bridge, the second member facing the upper surface of the valve bridge and having a second surface at a predetermined distance from the upper surface of the valve bridge. In this case, the second fixed position of the second member is aligned with a second engine valve of at least two engine valves, the second engine valve being the closest to the rocker shaft of the internal combustion engine. The first member may be configured to be attached to the cylinder head of the internal combustion engine, while the second member may form an integral structure with the rocker shaft pedestal of the internal combustion engine.

[0010] In a further alternative of this second main embodiment, the valve bridge guide may further include a bridge pin disposed at one end of the valve bridge and aligned with an engine valve of at least two engine valves. Alternatively, the first member of the valve bridge guide in this embodiment may be configured to be attached to the cylinder head and include an arch extending between at least two engine valves and over the upper surface of the valve bridge, the arch having an opening formed therein that is further aligned with a portion of the valve bridge that contacts the valve train component.

Brief Description of the Drawings

[0011] The features described in this disclosure are set forth in detail in the appended claims. These features and attendant advantages will become apparent from consideration of the following detailed description in conjunction with the accompanying drawings. Here, by way of example only, one or more embodiments will be described with reference to the accompanying drawings in which like reference numerals represent like elements.

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[0012] Figs. 2 - 36 illustrate various embodiments of a valve bridge system with a valve bridge guide according to the present disclosure. In all of the embodiments and variations illustrated in Figs. 2 - 36, it is assumed that the valve bridge is of the type illustrated in Fig. 1, i.e., a valve bridge having the general type of locking mechanism illustrated in Fig. 1 and described above.

[0013] FIG. 2 illustrates a first embodiment according to the present disclosure in which the internal combustion engine 202 includes a pair of valve bridges 204, 212 for a single cylinder. In the illustrated embodiment, each valve bridge 204, 212 actuates two corresponding engine valves, although it is possible for each valve bridge to actuate more than two engine valves. As is known in the art, each valve bridge 204, 212 (or any of the other valve bridges illustrated and described herein) may actuate two engine valves of the same type, i.e., two intake valves or two exhaust valves. For ease of illustration, only the features and operation of the first valve actuation system according to the first embodiment are described, but it is understood that the described features and operations are equally applicable to all valve bridges included in the internal combustion engine.

[0014] Accordingly, as shown, the first valve bridge 204 spans a pair of engine valves in a conventional manner known in the art (not visible in FIG. 2). Each engine valve has valve springs 208, 210 that bias its corresponding engine valve to a closed state (i.e., the state where the engine valve head engages a valve seat formed in the cylinder head 230), and valve spring retainers 209, 211 attached to the valve stems of the engine valves. Further shown, the valve bridge system 202 further includes a valve bridge guide 206 that extends downward (i.e., in the direction of the cylinder head and away from the rocker arm 220) from the valve bridge 204 and between the valve springs 208, 210. In one embodiment, the distance that the valve bridge guide 206 extends between the valve springs 208, 219 is minimally defined by that portion of the valve bridge 204 that surrounds the locking mechanism (e.g., referring to FIG. 1, the depth of that portion of the valve bridge that houses the outer plunger 720 and the outer plunger spring 746). In the embodiment illustrated in FIG. 2, the valve bridge and the valve bridge guide form an integral structure, i.e., an overall portion that is not divided, whereby the locking mechanism is housed within an opening (best shown in FIG. 3) formed in the valve bridge 204 and the valve bridge guide 206. As will be described in more detail below, the valve bridge guide 206 includes at least one valve bridge control surface configured to interact with one or both of the valve springs 208, 210 or the valve spring retainers 209, 211 to prevent, minimize, or at least accommodate uncontrolled movement of the valve bridge 204.

[0015] Figure 3 illustrates a cross-sectional view of the valve spring guide 206 and the first valve spring 208 taken along section line III-III (as shown in Figure 2). An opening 310 for accommodating the locking mechanism is formed in the valve spring guide 206, and Figure 3 further illustrates the valve stem 320 disposed within the corresponding valve spring 208. More specifically, Figure 3 illustrates that the valve bridge control surface 402 conforms to the corresponding valve spring 306 (only one is shown in Figure 3), i.e., the valve bridge control surface 402 is concave with respect to the convex outer surfaces of the valve springs 208, 210, and is defined by the valve bridge guide 206 to form two valve bridge control surfaces 402. Although they are in conformity, the valve bridge control surfaces 402 are configured such that during the controlled state of the valve bridge, the valve bridge control surfaces 402 (and thus the valve bridge guide 206) can avoid contact with their corresponding valve springs 208, 210. The valve bridge control surfaces 402 are configured to be as close as possible (within manufacturing tolerances) to the valve springs 208, 210 such that the normal movement and vibration of the valve bridge 204, the valve bridge guide 206, and the valve springs 208, 210 are insufficient to cause contact between the valve bridge control surfaces 402 and the valve springs 208, 210. For example, as is known in the art, when a compression spring such as the valve springs 208, 210 is deformed (i.e., compressed), the outer diameter of the spring increases slightly. Thus, the valve bridge control surfaces 402 can be configured to take into account the expected maximum change in the spring diameter while remaining as close as possible to the valve springs 208, 210.

[0016] In some cases, it may be undesirable for the valve bridge guide 206 to contact the valve springs 208, 210, as this could otherwise lead to premature deterioration of the valve springs 208, 210. Therefore, in some cases, it may be desirable to configure the valve bridge control surface 402 to contact the spring retainers 209, 211 instead. To achieve this configuration, the spring retainers 209, 211 may need to have an outer diameter larger than the outer diameter of the valve springs 208, 210. In this case, the valve bridge control surface 402 is instead defined by the valve bridge guide 206 such that the valve bridge control surface 402 conforms to the corresponding spring retainers 209, 211, i.e., the valve bridge control surface 402 is concave with respect to the convex outer surfaces of the spring retainers 209, 211. Also in this case, such a concave surface is configured such that during the controlled state of the valve bridge, the valve bridge control surface 402 can avoid contact with their corresponding spring retainers 209, 211, and further, the normal movement and vibration of the valve bridge 204, the valve bridge guide 206, and the valve springs 208, 210 are insufficient to cause contact between the valve bridge control surface 402 and the spring retainers 209, 211, and are configured to be as close as possible (within manufacturing tolerances) to the valve springs 208, 210.

[0017] Although the various figures illustrated and described in this disclosure show at least two concave valve bridge control surfaces 402, this is not necessarily a requirement. For example, a single such valve bridge control surface 402 may be employed when used in combination with another feature that provides additional control of otherwise uncontrolled movement of the valve bridge 204. For example, if the valve bridge 204 includes a bridge pin (see, e.g., element 2102 of FIG. 21), the combination of a single valve bridge control surface 402 and the bridge pin may be sufficient.

[0018] The configuration of the valve bridge control surface 402 according to the preferred embodiment is further described in connection with FIG. 4, which schematically illustrates in an enlarged form the valve bridge guide 206 and the valve spring 208. (Alternatively, as described above, the valve spring 208 illustrated in FIG. 4, although only the valve spring 208 is described herein for ease of explanation, can be regarded as a spring retainer.) As shown, the valve bridge guide 206 includes a concave valve bridge control surface 402 proximate to the outer diameter 408 of the valve spring 208. In practice, the clearance between the valve bridge control surface 402 and the outer diameter 408 is based in part on the manufacturing tolerances of the valve springs 208, 210 (or spring retainers 209, 211) and the valve bridge 204. Further, this clearance is based on the clearance of the tip of the engine valve within the receptacle formed in the valve bridge 204 for receiving the tip of the engine valve. For example, if the valve bridge 204 is allowed to move ±0.25 mm, the clearance between the valve spring 208 and the valve bridge control surface 402 must be greater than the allowable 0.25 mm play in the component tolerances. Further, the chamfer at the bottom of the valve bridge 204 must be large enough so that the valve bridge 204 can relocate itself onto the tip of the engine valve even if the valve bridge 204 experiences uncontrolled movement over the full clearance to the valve spring or spring retainer.

[0019] As further shown in FIG. 4, the circumferential length of the concave valve bridge control surface 402 (with respect to the outer diameter 408 of the spring 208) is defined by both edges 404, 406. In this preferred embodiment, both edges 404, 406 are spaced apart such that when the valve bridge guide 206 is positioned during the controlled state of the valve bridge 204, a line 410 intersecting both edges 404, 406 as shown forms at least a secant line with respect to the outer diameter 408 of the valve spring 208. When configured in this way, any movement of the valve bridge guide 206 in either direction indicated by the line 410 (for example, which may occur during the uncontrolled state of the valve bridge 204), if large enough, will bring the concave valve bridge control surface 402 into contact with the spring outer diameter 408, whereby it will be understood that the valve bridge guide 206 will move away from the valve spring 208 and generally deflect in the direction towards the other valve spring 210. More generally, any rotational movement of the valve bridge 204 about the axis of the center line of the locking mechanism is also constrained, similar to the lateral movement in both horizontal planes. Keeping this in mind and referring back to FIGS. 2 and 3, this operation of the concave valve bridge control surface 402 during the uncontrolled state of the valve bridge 204 has a tendency to realign the valve bridge guide 206 itself with the valve springs 208, 210, thereby effectively damping or even eliminating the uncontrolled movement of the valve bridge 204 and the valve bridge guide 206.

[0020] Referring now to FIGS. 5 and 6, a first variant of the valve bridge guide 502 comprises a single body separate from the valve bridge 204 and having a valve bridge control surface 402 formed on its side surface as shown. The valve bridge 204 is also illustrated as having a receptacle 614 for receiving the tip of the valve stem of an engine valve, as is known in the art and described above. In this embodiment (as well as further embodiments illustrated in FIGS. 7-13), the valve bridge guide 502 may be manufactured from the same material (e.g., steel) as the valve bridge 204, but in a preferred embodiment, the valve bridge guide 502 is formed of a lighter and stronger material, despite being softer than the valve bridge springs 208, 201 (or spring retainers 209, 211), to avoid being damaged or scratched. For example, a suitable moldable polymer, such as those known in the art, may be used for this purpose. Still further types of materials for manufacturing the valve bridge guide will be apparent to those skilled in the art.

[0021] Anyway, as further shown, the valve bridge guide 502 has an internally formed opening or bore 602 configured to snugly receive the portion 604 of the valve bridge 204. As shown, the portion 604 of the valve bridge 204 received by the valve bridge guide 502 preferably houses at least a portion of the locking mechanism 606. As further shown, in this embodiment, both the valve bridge guide 502 and the portion 604 of the valve bridge 204 include fastener receiving features 504, 608. In this embodiment, the fastener receiving feature 504 of the valve bridge guide includes a bore that intersects the opening 602 formed in the valve bridge guide 502. Thus, at the location where the bore intersects the opening 602, the fastener receiving feature 504 essentially comprises a channel having a semi-circular cross-section formed in the sidewall of the opening 602. In a complementary manner, the fastener receiving feature 608 of the portion 604 of the valve bridge 204 is also formed as a semi-circular channel in the outer wall surface of the portion 604. When aligned, these respective fastener receiving features 504, 608 can receive fasteners 610, 612 such that the valve bridge guide 502 is operably connected to the portion 604 of the valve bridge 204. For example, in the illustrated embodiment, the fastener 612 can comprise a split cotter pin as shown, but those skilled in the art will recognize that other types of fasteners, such as screws, can equally be employed. In this way, the valve bridge guide 502 is relatively firmly attached to the valve bridge 204 such that they move together. As an alternative to the fastener embodiments described above, the valve bridge guide 502 (or other embodiments of the valve bridge guide illustrated in FIGS. 7-13) can instead be fixedly attached to the valve bridge 204 using a suitably strong and durable epoxy or similar adhesive. Further, a combination of such techniques can also be employed as a design option.

[0022] Referring now to FIGS. 7 and 8, a second variant of the valve bridge guide 702 comprises a separate unit from the valve bridge 204 having a valve bridge control surface 402 formed on its side surface, and is substantially similar to the valve bridge guide 502 of FIGS. 5 and 6 in that respect. However, in this embodiment, the valve bridge guide 702 extends inwardly from the side wall surface of the opening 602 and comprises one or more teeth 802 configured to engage with a notch 804 formed on the outer side wall surface of the portion 604 of the valve bridge 204. For example, the notch 804 may comprise an annular groove or channel formed on the side wall of the portion 604 of the valve bridge 204. When the teeth 802 engage with the notch 804, the valve bridge guide 702 is operably connected to the valve bridge in a relatively rigid manner such that the valve bridge guide 702 and the valve bridge 204 move together. It should be noted that in this embodiment, the arrangement of the one or more teeth 802 and the notch 804 can be reversed equally, that is, the teeth 802 can be formed on the outer side wall surface of the portion 604 of the valve bridge 204, and the notch 804 can be formed on the inner side wall surface of the opening 602.

[0023] As further shown in FIG. 7, the valve bridge guide 702 may comprise at least two projecting members 704, 706 projecting from the valve bridge guide 702 towards the valve bridge 204. As shown in FIG. 8, the valve bridge 204 has a lower surface 806, and in one embodiment, the projecting members 704, 706 extend at least beyond the lower surface 806 of the valve bridge 204. In this embodiment, the at least two projecting members 704, 706 help to orient the valve bridge guide 702 on the valve bridge 204, thereby preventing rotation of the valve bridge 204 relative to the valve bridge guide 702. In this way, the at least two projecting members 704, 706 further help to align the valve bridge control surface 402 with the valve springs 208, 210 or the spring retainers 209, 211.

[0024] Referring now to FIGS. 9 and 10, a third modification of the valve bridge guide 902 is illustrated. As shown, the valve bridge guide 902 is in this case also formed as a single body separate from the valve bridge 204 and has a valve bridge control surface 402 formed on its side surface. However, in this embodiment, the valve bridge guide 902 has a side opening 904 having a cantilever latch or catch 906 disposed therein. As shown, the catch 906 is configured to engage a corresponding notch 1002 formed in the outer side wall surface of the portion 604 of the valve bridge 204. For example, also in this case, the notch 1002 may comprise an annular groove or channel formed in the side wall of the portion 604 of the valve bridge 204. When the catch 906 engages the notch 804, the valve bridge guide 702 is operatively connected to the valve bridge in a relatively rigid manner such that the valve bridge guide 902 and the valve bridge 204 move together. As shown, the valve bridge guide 902 may further comprise a secondary latch surface 908 configured to engage a corresponding secondary notch 1004 formed in the portion 604 of the valve bridge 204. By providing a plurality of latch pairs 906, 1002 / 908, 1004, the stability of the valve bridge guide 902 with respect to the valve bridge 204 can be improved.

[0025] Referring now to FIG. 11, a fourth modification of the valve bridge guide 1102 is shown. In this modification, the valve bridge guide 1102 is a single unit disposed between the spring retainers 209, 211 and the valve bridge 204. The notches 1104, 1106 are provided to enable the valve bridge guide 1102 to be positioned relative to the tip of the engine valve. Further, a central opening 1107 may be provided that enables a portion of the valve bridge 204 (e.g., the portion that houses the locking mechanism as shown in FIG. 1) to extend through the valve guide 1102. Similar to the embodiments of FIGS. 7 and 8, the valve bridge guide 1102 includes at least two projecting members in the form of side walls 1108, 1110 that define a channel 1116, and the channel 1116 is configured to receive the valve bridge 204. In this embodiment, the inner surfaces 1112, 1114 of the side walls 1108, 1110 that rise above the valve bridge 204 function as valve bridge control surfaces that prevent lateral movement or rotation of the valve bridge 204 that may occur during an uncontrolled state of the valve bridge 204. Further, although not shown in FIG. 11, as described above, an additional valve bridge control surface 402 may optionally be provided at the lower portion 1118 of the valve bridge guide 1102 to prevent tilting of the valve bridge 204. As long as the valve bridge guide 1102 is fixedly attached to the valve bridge 204 (using any of the techniques described above), excessive lifting of the valve bridge 204 (e.g., detachment from the tip of the engine valve) will cause a similar lifting within the valve bridge guide 1102, which again resists uncontrolled movement and enables the valve bridge 204 to settle back onto the tip of the engine valve.

[0026] Referring now to FIG. 12, a fifth variation of the valve bridge guide 1202 is substantially similar to the valve bridge guide 502 of FIGS. 5 and 6 in that it comprises a single body separate from the valve bridge 204 and having a valve bridge control surface 402 formed on its side surface as shown. Further as shown and similar to the second variation illustrated in FIGS. 7 and 8, this embodiment of the valve bridge guide 1202 further comprises a plurality of projecting members 1204-1212 extending upwardly from the body of the valve bridge guide 1202, which serve the same purpose as above. Further, as shown, each of the projecting members 1204-1212 comprises mounting surfaces 1214, 1216 (only two are shown in FIG. 12) in the form of inwardly extending fingers 1214, 1216 disposed at the ends of the projecting members 1204-1212. The mounting surfaces thus defined are configured to engage corresponding surfaces 1220 of the valve bridge 204, in this case the upper surface of the valve bridge 204. In this way, the valve bridge guide 1202 is held on the valve bridge 204. Alternatively, similar to the embodiment of FIGS. 9 and 10, the fingers 1214, 1216 may instead engage notches or similar features formed in the side surfaces of the valve bridge 204.

[0027] FIG. 13 illustrates a sixth variation of the first embodiment, in which the valve bridge guide 1302 is formed from two guide members 1304, 1306 configured to engage both sides of the valve bridge. Similar to other embodiments, each of the guide members 1304, 1306 defines a valve bridge control surface 402 as described above. Further, each of the guide members 1304, 1306 defines a first opening 1308 (only one is shown) configured to receive a portion 604 of the valve bridge 204 (not shown). As further shown, each of the guide members 1304, 1306 also includes a channel or second opening 1310 configured to receive one of the arms of the valve bridge 204 (i.e., that portion of the valve bridge extending from the center of the valve bridge to one of the engine valves). Additionally, each of the guide members 1304, 1306 includes fasteners in the form of complementary first latches 1312 and first latch notches 1314 and second latches 1316 and second latch notches 1318 such that the guide members 1304, 1306 can be fixedly connected to each other. Alternatively, any of the above attachment mechanisms (such as alignment pins, epoxy, etc.) can be used as a "fastener" for this purpose. When connected, the guide members 1304, 1306 together define a valve bridge guide 1302 that is maintained in a predetermined position relative to the valve bridge 204 by the fact that the second opening 1310 encompasses the arm of the valve bridge 204.

[0028] Figures 14 and 15 illustrate a seventh variation of the first main embodiment in which the valve bridge guide 1402 is formed as a punched sheet metal structure having a horizontal plane 1404 and continuous side walls 1406 extending downward therefrom. In this variation, similar to the embodiment illustrated in FIG. 11, the valve bridge guide 1402 is designed to be placed above the spring retainers 209, 211 (FIG. 15) and below the valve bridge 204 (not shown). In FIG. 15, the side walls 1406 are shown extending beyond the spring retainers 209, 211 and the initial portions of the valve springs 208, 210. In one embodiment, the extent of the side walls 1406 is such that the valve bridge guide 1402 cannot be completely lifted off the spring retainers 209, 211 even when a vertical displacement is applied to the valve bridge 204. In addition to the central opening 1406 that allows passage of a portion of the valve bridge 204, the valve bridge guide 1402 also includes a plurality of projecting members 1408 - 1416 (four are shown in the example illustrated), similar to those illustrated in FIGS. 7, 8, 11, and 12. As shown, the projecting members 1408 - 1416 are formed as upwardly bent portions of the horizontal plane 1404, resulting in openings 1426, 1428 that allow passage of the tip of the engine valve 1502. In this case, the projecting members 1408 - 1416 also define valve bridge control surfaces 1422, 1424 here to resist the uncontrolled movement of the valve bridge 204.

[0029] FIG. 16 illustrates an isometric view of an eighth variation of a first main embodiment, where valve bridge guide 1602 comprises two guide members 1603 (only one is shown) configured to engage on both sides of valve bridge 204 (not shown). Each guide member 1603 is formed as a punched sheet metal structure having a horizontal plane 1604 and continuous side walls 1606 extending downward therefrom, as in the embodiments of FIGS. 14 and 15, but is configured to rest on only a single spring retainer 209. Also in this case, each guide member 1603 includes a plurality of projecting members 1608, 1610 extending upwardly and a central opening 1612 for passage of the tip of the engine valve, and each of the projecting members 1608, 1610 defines a valve bridge control surface 1614 for resisting uncontrolled movement of valve bridge 204.

[0030] Similar to the embodiment of FIG. 16, the embodiment illustrated in FIG. 17 includes a valve bridge guide 1702 having a pair of guide members 1703 configured to be placed on separate spring retainers 209, 211. In this case, formed from a moldable polymer, each guide member 1703 includes a horizontal plane 1704 and continuous side walls 1706 extending downward therefrom, similar to the embodiments of FIGS. 14 and 15, but is configured to be placed only on a single spring retainer 209 as in the embodiment of FIG. 16. Also in this case, each guide member 1603 includes a plurality of projecting members 1708, 1710 extending upwardly and a central opening 1712 for passage of the tip of the engine valve, each of the projecting members 1708, 1710 defining a valve bridge control surface 1614 for resisting uncontrolled movement of the valve bridge 204. However, in this case, each guide member 1703 is also provided with a lateral concave valve bridge control surface 402 as described above. However, in this case, the lateral concave valve bridge control surface 402 is not configured to conform to the outer surfaces of the valve springs 208, 210, but is configured to conform to that portion of the valve bridge 204 that extends downwardly between the valve springs 208, 210 to accommodate a locking mechanism, as described and illustrated above in connection with FIG. 1.

[0031] Referring now to FIGS. 18-21, a second major embodiment according to the present disclosure is illustrated, and the internal combustion engine 202 includes a pair of valve bridges 204, 212 for a single cylinder. In the illustrated embodiment, each valve bridge 204, 212 actuates two corresponding engine valves, but again, it is possible for each valve bridge to actuate three or more engine valves. In the illustrated embodiment, the first valve bridge 204 spans a pair of engine valves in a conventional manner known in the art. Each engine valve has valve springs 208, 210 that bias the corresponding engine valve to the closed position and valve spring retainers 209, 211 attached to the valve stems of the engine valves. As best shown in FIG. 19, the valve bridge 204 includes a lower surface 1902 facing the engine valves and an upper surface 1904 opposite the lower surface 1902.

[0032] As further shown in this second main embodiment, the valve bridge system further comprises a valve bridge guide in the form of a first member 1802 having a first surface 1906 facing the upper surface of the valve bridge 204. Using suitable fasteners 1806 (such as bolts screwed into the cylinder head or similar fixed structures), the first member 1802 is maintained in a first fixed position relative to the valve bridge 204. In particular, the first fixed position maintains the first member at a predetermined distance 1908 from the upper surface of the valve bridge 204 when at least two valve bridges are maintained in the closed state. Further, as shown, the first fixed position of the first member 1802 is aligned with the first engine valve of at least two engine valves, and the first engine valve is the farthest from the rocker shaft 1808 of the internal combustion engine 202. As shown, the first member 1802 can be configured to align with the first engine valve for two or more valve bridges 204, 212, as described. Further, the first member 1802 can also extend across the valve bridges of multiple cylinders of the internal combustion engine in this problem, or can comprise a plurality of such first members 1802 if the cylinder configuration prevents the use of a single first member 1802.

[0033] In this embodiment, the predetermined distance 1908 between the first member 1802 and the upper surface 1904 of the valve bridge 204 is preferably sufficient to prevent contact between the first surface 1906 of the first member 1802 and the upper surface 1904 of the valve bridge 204 when the valve bridge 204 is in a controlled state with respect to at least two engine valves, and is sufficient to allow contact between the first surface 1906 and the upper surface 1904 to resist the uncontrolled movement of the valve bridge 204 when the valve bridge 204 is in a state where it is not controlled with respect to at least two engine valves. As used herein, the uncontrolled movement of the valve bridge 204 is resisted to the extent that any of the disclosed valve bridge guides resists the movement of the valve bridge outside its normal range of movement when operating in a controlled state. Thus, the plurality of variations of the first embodiment illustrated in FIGS. 2-12 counter the movement that can cause the inclination or rotation of the valve bridge 204 with respect to the engine valves, but the first member 1802 counters the excessive vertical displacement of the valve bridge 204 with respect to the engine valves, and in particular, prevents the valve bridge 204 from completely disengaging from the engine valves. By defining a predetermined distance 1908 relative to the closed position of the engine valve, contact between the valve bridge 204 and the first member 1802 is avoided during the controlled operation of the valve bridge 204. However, by further defining the predetermined distance 1908 to be sufficiently small nevertheless, a desired resistance to the uncontrolled movement of the valve bridge 204 can be provided. In one embodiment, the predetermined distance 1908 can be based on the depth 2002 of the receptacle 2004 provided by the valve bridges 204, 212 for engaging the valve tip 2006 of the engine valve (FIG. 20). In particular, the predetermined distance 1908 can be selected to be shorter than the depth 2002 of the receptacle 2004.In this way, when the valve bridges 204, 212 operate in an uncontrolled state, they contact the first member 1802 before they can move a distance exceeding the depth 2002 of the receptacle 2004; otherwise, the valve bridges 204, 212 may disengage from the valve tip 2006. Further, in some forms of engine braking, it is known to operate only a single installed engine valve (i.e., the one closest to the rocker shaft), thereby engaging that portion of the valve bridge with an external engine valve (i.e., the one farthest from the rocker shaft) and lifting it slightly upward, for example, by about 1 - 2 mm. Therefore, the predetermined distance 1908 should be selected to accommodate this possibility in order to avoid undesirable contact with the valve bridge 204. Further, normal wear of the engine valve seat may cause the tip of the engine valve to rise over time, and the predetermined distance 1908 also needs to take this possibility into account.

[0034] In this second embodiment, the valve bridge guide may further include a second member 1804 that is maintained in a second fixed position relative to the valve bridge 204 and has a second surface 1910 facing the upper surface 1904 of the valve bridge 204. Similar to the first member 1802, the second surface 1910 is maintained at a predetermined distance 1908 from the upper surface 1904 for the same reasons described above. In one embodiment, the second fixed position of the second member 1804 is aligned with a second engine valve of at least two engine valves, and the second engine valve is the one closest to the rocker shaft 1808. Further, as best shown in FIGS. 18 and 19, the second member 1804 may be formed as an integral structure with the rocker pedestal 1810. In this way, the first and second members 1802, 1808 can be aligned separately with different engine valves and at the same predetermined distance 1908 from the upper surface 1904, thereby functioning as a valve bridge guide that provides uniform resistance to uncontrolled movement.

[0035] As is known in the art, some valve actuation systems include an auxiliary motion source and a valve train that provide auxiliary motion to a single engine valve despite the presence of a valve bridge 212. This is accomplished by the use of a bridge pin 2102 that, as is known in the art, enables the application of auxiliary valve actuation motion to a single engine valve and also enables the application of primary valve actuation motion to a single engine valve via the valve bridge 212. In this case, the presence of the bridge pin 712 passing through the valve bridge 212 effectively functions as a second member that defines a valve bridge guide. That is, when the valve bridge 212 operates in an uncontrolled state, the presence of the bridge pin 712 (operatively connected to both the auxiliary rocker arm 2104 and a single engine valve) operates to constrain the valve bridge 212 to only sliding motion relative to the bridge pin 712. In this case, the presence of the auxiliary rocker arm 2104 (or other auxiliary valve train component) operates to prevent movement of the valve bridge 212 away from the bridge pin 2102. Again, when a first member 1802 is provided (as shown), the combined operation of the first and second members resists uncontrolled movement of the valve bridge 212, particularly upward movement.

[0036] FIG. 22 illustrates a first variation of a second embodiment in which the valve bridge guide comprises a first member 2202 formed as a three-sided "strap". Similar to the embodiments of FIGS. 18-21, the variation illustrated in FIG. 22 operates to resist uncontrolled movement by positioning the first member 2202 at a location that contacts the upper surface 1904 of the valve bridge. In this embodiment, the first member 2202 may comprise sheet metal or a similar material having two substantially vertical elongated sides 2204 (one shown in FIG. 22) that extend from above the valve bridge 214 to the base of the engine valve springs 208, 210, each of the elongated sides 2204 being attached to the cylinder head 230. Above the highest normal rest point of the valve bridge 214 (i.e., when the engine valve is fully closed) and above the upper surface 1904 of the valve bridge 214, a third substantially horizontal side 2206 of the first member 2202 connects the first and second elongated sides 2204. Similar to the embodiments of FIGS. 18-21, the third side 2206 is preferably maintained in a fixed position a predetermined distance 1908 (not shown in FIG. 22) from the upper surface 1904. As further shown, the third side 2206 includes an opening 2210 that allows a portion of the valve bridge 214 (e.g., the outer plunger 720 / cap 730, referring to FIG. 1) to contact the rocker arm 2212 as shown. Thus, in this variation, the displacement of the valve bridge 204 is constrained by the third side 2206 of the first member 2202 and the opening 2206 formed therein.

[0037] FIG. 23 is a cross-sectional view of a valve bridge that illustrates the drawbacks of prior art systems. In particular, FIG. 23 illustrates a valve bridge having a valve bridge body 2302 that spans two engine valve systems 2304, 2306. As shown, the first engine valve 2306 is actuated by an auxiliary rocker arm 2312 via a bridge pin 2308 that receives the stem of the first engine valve 2306. The bridge pin 2308 is then received within a through bore 2310 formed within the valve bridge body 2302 and aligned with the first engine valve 2306, thereby enabling the bridge pin 2308 to contact the auxiliary rocker arm 2312. Further, the valve bridge body 2302 includes a receptacle 2314 configured to align with and receive the stem of the second engine valve 2304. In FIG. 23, the valve bridge 2302 is depicted in an uncontrolled state as by the receptacle 2314 losing contact with the second engine valve 2304. This results from the fact that there is no surface provided to inhibit upward movement of the valve bridge 2302 during the uncontrolled state.

[0038] FIG. 24 illustrates a valve bridge according to a third main embodiment, showing a valve bridge substantially similar to that depicted in FIG. 23. However, in this case, the valve bridge also has a through bore 2404 formed therein and includes a bridge pin boss 2402 having a greater longitudinal length (or height) compared to the embodiment illustrated in FIG. 23. As a result, the upper surface 2406 of the bridge pin boss 2402 is closer to the lower surface 2408 of the auxiliary rocker arm 2312 (e.g., the lower surface of the actuator in the depicted embodiment). Thus, when the valve bridge is in an uncontrolled state that results in an upward movement of the valve bridge body 2302, the upper surface 2406 of the bridge pin boss 2402 contacts the lower surface 2408 of the auxiliary rocker arm 2312 before the valve bridge body 2302 has the possibility of completely disengaging from the valve stem. This is illustrated in FIG. 24, and the contact between the upper surface 2406 and the lower surface 2408 prevents complete disengagement of the receptacle 2410 from the stem of the second engine valve 2304.

[0039] It is also understood that a similar upper surface of that portion of the valve bridge body 2302 aligned with the main rocker arm 2412 can be configured in a similar manner to the upper surface 2406 of the bridge pin boss 2402. In this case, the height of the valve bridge body 2302 aligned with the main rocker arm 2412 can be similarly increased such that during an uncontrolled movement of the valve bridge body 2302, the upper surface 2411 of the valve bridge body 2302 is likely to contact the main rocker arm 2412 (e.g., the lower surface of the pivot foot in the depicted embodiment). However, in this case, the height of the upper surface 2411 must be selected so as not to prevent the folding mechanism 2412 from being able to completely absorb any valve actuation movement provided by the main rocker arm 2412. In other words, the upper surface 2411 should not be increased to the point of contacting the main rocker arm 2412 during a controlled state (or controlled movement) of the valve bridge body 2302 and when the folding mechanism 2414 is absorbing the main valve event.

[0040] Referring now to FIG. 25, a valve bridge according to the fourth to sixth main embodiments is illustrated. In particular, FIG. 25 again illustrates a valve bridge having a configuration similar to the valve bridge illustrated in FIG. 23. The fourth main embodiment relates to the feature of the clearance between the inner diameter of the through bore 2502 and the outer diameter of the bridge pin 2504. In particular, by tightly controlling and minimizing the clearance between the through bore and the bridge pin, the occurrence of uncontrolled movement will result in a "pinch" (or interference) of the valve bridge body 2302 and the bridge pin 2504. This is illustrated in FIG. 25 by the contact point 2505 between the through bore 2502 and the bridge pin 2504. Next, this pinch dampens any further movement of the valve bridge body 2302, thereby tending to keep the valve bridge body 2302 aligned with the engine valve.

[0041] FIG. 25 further illustrates the fifth main embodiment in the context of depicting a spring retainer 2506 of increased radius (relative to the radius of a typical spring retainer 2510, i.e., comparable to the radius of a valve spring (not shown)). In this embodiment, the increased radius spring retainer 2506 allows that portion 2508 of the valve bridge body 2302 that extends between the engine valve stems to contact 2511 the increased radius spring retainer 2506 more quickly during uncontrolled movement (in particular, rotation of the valve bridge body 2302), thereby resisting further rotation of the valve bridge body 2302.

[0042] Furthermore, FIG. 25 further illustrates a sixth main embodiment in terms of showing the features of the extending valve stem. In the illustrated embodiment, the feature of the extending valve stem takes the form of a bridge pin 2512 present in the second through bore 2518. As shown, the bridge pin 2512 is free to move up and down on the engine valve stem 2514. In this case, when the valve bridge body 2302 is in an uncontrolled state, the bridge pin 2512 is free to move upward together with the valve bridge body 2302. Despite the uncontrolled movement of the bridge pin 2512 and the valve bridge body 2302, as long as the bridge pin 2512 remains seated on the engine valve stem 2514, the bridge pin 2512 maintains the alignment of the valve bridge body 2302 with the engine valve stems 2514, 2516. As shown, the same principle of controlled movement on the engine valve stem 2516 can be equally applied to the bridge pin 2504 aligned with the auxiliary rocker arm. In this embodiment, it may be desirable for either or both of the engine valve stems 2514, 2516 to have an extended length that exceeds the spring retainers 2506, 2512, for example, a maximum extended length of 10 mm compared to a more typical length of 2 - 3 mm.

[0043] Figures 26-28 illustrate a valve bridge according to a seventh main embodiment. According to a typical valve bridge, the illustrated valve bridge includes a valve bridge body 2602 spanning at least two engine valves 2604, 2606. In this embodiment, slots 2608 are formed in those portions of the valve bridge body 2602 configured to contact the stems of the engine valves 2604, 2606. In particular, as best shown in FIG. 28, the slot 2608 may comprise a laterally extending slot that intersects transversely the longitudinal axis 2806 (only one is shown in FIG. 28) of the engine valve stem 2604 and the receptacle 2802. When the engine valve stem 2604 is aligned with and inserted into the corresponding receptacle 2802, an annular channel 2804 formed in the engine valve stem 2604 is aligned with the slot 2608. A C-clip 2702 is inserted into the slot 2608 and engages the annular channel 2804 such that the C-clip 2702 is retained on the engine valve stem 2604. When retained on the engine valve stem 2604, further engagement of the C-clip 2702 with the slot 2608 enables the C-clip 2702 to resist disengagement of the engine valve stem 2604 from the receptacle 2802, for example, during uncontrolled movement of the valve bridge body 2602. The slot 2608 is illustrated in FIGS. 26-28 as extending laterally away from the valve bridge body 2602, but this is not a requirement. For example, the slot 2608 could instead extend perpendicular to the plane of FIG. 28, i.e., perpendicular to the longitudinal axis of the valve bridge body and perpendicular to the longitudinal axes 2806 of the engine valve stems 2604, 2606.

[0044] FIG. 29 is a side view of a valve bridge according to an eighth main embodiment. In this embodiment, the valve bridge body 2902 includes a protrusion 2904 that extends downward from the lower surface 2908 of the valve body 2902 and is positioned between at least two engine valve stems (not shown). As further shown, the protrusion 2904 has at least one hook feature 2906 (only one is shown) that extends away from the protrusion 2904 toward and below at least one spring retainer 2910 such that the hook or latch feature 2906 extends beyond the outer periphery of the at least one spring retainer 2910. When the valve bridge body 2902 is in an unregulated state, the hook feature 2906 contacts the lower surface 2912 of the valve spring retainer 2910 and prevents the valve bridge body 2902 from separating from the engine valve stem until the valve bridge body is completely disengaged from the engine valve stem. Similar to the fifth embodiment described above in connection with FIG. 25, the increased radius spring retainer 2910 can provide a protruding rim of material that extends beyond the outer periphery of the corresponding valve spring 2914. In this way, the hook feature 2906 can engage better with the spring retainer 2910, thereby better ensuring resistance to disengagement of the valve bridge.

[0045] As further shown in FIG. 29, the peripheral shape 2914 of the protrusion 2904 is configured to allow the valve bridge body 2902 to move downward over one of the engine valves (the right end as depicted in FIG. 29, in the case of the auxiliary valve actuation movement) and tilt without contacting the springs 2914, 2918. Based on the illustrated configuration, the installation of the valve bridge is facilitated by first installing the left side and then rotating the valve bridge downward onto the engine valve stem at the right end (and the corresponding bridge pin 2920). The bridge pin 2920 is pushed down by a separate auxiliary rocker or its integral actuator piston (not shown), but the bridge cannot be removed due to the latching effect of the hook feature 2906.

[0046] Figures 30 and 31 illustrate a valve bridge and bridge pins according to a ninth main embodiment. In this embodiment, the valve bridge body 3002 includes open laterally extending slots 3004, 3006 defined between respective arms 3022, 3024 extending within the valve body 3002 and configured to receive corresponding bridge pins 3008, 3010. As best shown in FIG. 31, each bridge pin 3008, 3010 has a receptacle 3102 formed therein and configured to receive a corresponding engine valve system 3012. As shown, each of the bridge pins 3008, 3010 has a spool-like shape including a barrel body 3016 and end caps 3018, 3020 of increased diameter (relative to the barrel body 3016). The slots 3004, 3006 are configured such that the arms 3022, 3024 maintain a relatively close clearance to the barrel body 3016 of their respective bridge pins 3008, 3010. On the other hand, the slots 3004, 3006 are configured such that the arms 3022, 3024 contact the end caps 3018, 3020. In this way, the vertical movement of the bridge pins 3008, 3010 is constrained by the spacing 3104 between the upper (and / or lower) surfaces of the arms 3022, 3024 and the complementary surfaces defined by the end caps 3018, 3020. In this way, when the valve bridge body 3002 is subject to uncontrolled movement, the restraint placed on the valve bridge body 3002 by the bridge pins 3008, 3010 prevents disengagement from the engine valve systems 3012, 3014. Similar to the third main embodiment illustrated in FIG. 24, it should be noted that the upper surface 3026 of the valve bridge body 3002 can be configured such that the spacing between the upper surface 3026 and the end cap 3010 further restricts upward movement of the valve bridge body 3002.

[0047] FIG. 32 illustrates a valve actuation system according to prior art techniques. In particular, instead of a valve bridge 3206 as depicted in many of the embodiments described above, which is similar to that shown in FIG. 1, a valve actuation system deployed on a rocker arm 3202 or a push rod 3204 is known. As is known in the art, the rocker arm 3202 is fully engaged with a rocker shaft 3208, but such a valve actuation system presents an opportunity for the valve bridge 3206 to enter an uncontrolled state when excessive lash is formed within the valve train. For example, a sudden collapse within the push rod 3204 may allow the rocker to rotate rearward (i.e., toward the push rod 3204), which is equivalent to the sudden elimination of valve lift. If the valve lift lost in this way was relatively high (e.g., 14 mm in some systems), the sudden rearward rotation of the rocker arm 3202 may cause the rocker arm 3202 to strike the valve cover 3210 or other object. Since the valve bridge 3206 typically relies on the rocker arm 3202 to maintain engagement with the engine valve system, the sudden rearward rotation of the rocker arm 3202 combined with the rapid acceleration of the valve bridge 3206 under the influence of the valve spring moves the valve bridge in an uncontrolled manner and may in some cases result in disengagement.

[0048] To prevent the valve bridge 3206 from disengaging in such a situation, a stop may be provided to prevent excessive rotation of the rocker arm 3202 that would normally allow the valve bridge 3206 to disengage. This example is illustrated in FIG. 33 where a rigid or fixed block 3302 is deployed to prevent rearward rotation of the rocker arm 3202. In the illustrated embodiment, the fixed block 3302 is rigidly attached to the rocker shaft 3208 and, in this example, includes both a vertical surface 3304 and a horizontal surface 3306 configured to engage the surface of the rocker arm 3202 to prevent its excessive rotation. The fixed block 3302 is configured such that the vertical surface 3304 and the horizontal surface 3306 do not interfere with the normal reciprocating motion (i.e., the controlled state) of the rocker arm 3202. However, the fixed block 3302 is also configured such that the vertical surface 3304 and the horizontal surface 3306 are positioned to prevent excessive rotation of the rocker arm 3202.

[0049] For example, the illustrated rocker arm 3202 may, in this case, include a rear facing surface 3308 defined by a control valve boss formed in the rocker arm 3202. In the case of a sudden rearward rotation, the rear facing surface 3308 contacts the vertical surface 3304 and prevents excessive rotation of the rocker arm 3202. Similarly, the rocker arm further includes an upward facing surface 3310. In the case of a sudden rearward rotation, the rear facing surface 3310 contacts the horizontal surface 3306 and prevents excessive rotation of the rocker arm 3202. The illustrated embodiment includes both the vertical surface 3304 and the horizontal surface 3306, but this is not a requirement as it is expected that either such surface may be sufficient to prevent excessive rotation depending on the configuration of the rocker arm 3202.

[0050] Figures 34 and 35 illustrate a valve bridge and a valve bridge guide according to the eleventh embodiment. In this embodiment, a valve bridge guide 3404 attached to (or integrally formed with) a valve bridge body 3402 is provided. As shown, the valve bridge guide 3404 extends on a side surface of the valve bridge body 3402 and is not intended to engage an engine valve (not shown) actuated by an auxiliary motion source. In the illustrated embodiment, the valve bridge guide 3404 is formed as a half-cylinder wall configured to be attached to a lower surface 3502 of the valve bridge body 3402 such that the half-cylinder wall extends downward from the lower surface 3502. However, it is understood that the valve bridge guide 3404 can be attached to any other surface (e.g., the upper surface) of the valve bridge body 3402 as long as the half-cylinder wall extends downward below the lower surface 3502 as shown.

[0051] Figure 36 illustrates the valve bridge and the valve bridge guide of FIGS. 34 and 35 deployed in a valve actuation system. As shown, the valve bridge body 3402 spans two engine valve systems, and the valve bridge guide 3404 encompasses a lateral portion outside of a valve spring retainer 3602. The radius of the half-cylinder wall (preferably centered on or near the longitudinal axis of the corresponding engine valve system) is configured such that no contact occurs between the half-cylinder wall and the valve spring retainer 3602 or the corresponding valve spring 3604 during normal (i.e., controlled) operation of the valve bridge. On the other hand, the radius of the half-cylinder wall is further configured such that the half-cylinder wall contacts the valve spring retainer 3602 but avoids contact with the valve spring 3604 during an uncontrolled state of the valve bridge body 3402. Similar to the embodiments described above in connection with FIGS. 25 and 29, an increased-radius spring retainer can be used to more reliably ensure contact between the valve spring retainer 3602 and the spring retainer (preferably not the valve spring 3604).

[0052] As described above, the present disclosure describes various embodiments and variations of valve bridge guides that resist, i.e., can be used to prevent, minimize, or accommodate, the uncontrolled movement of the valve bridge. Although various features have been described in conjunction with specific embodiments, those skilled in the art will understand that various ones of such features can be incorporated into other embodiments described herein.

Claims

1. 1. A valve actuation assembly for use in actuating at least two engine valves in an internal combustion engine, comprising: a valve bridge having a valve bridge body configured to extend between the at least two engine valves, the valve bridge body including open, laterally extending slots extending into the valve body, each of the slots defining an arm; 1. A valve actuation assembly comprising: bridge pins each comprising a body with an oppositely formed end cap, each of the end caps having an increased diameter relative to the body, each body having a receptacle formed therein configured to receive a respective stem of an engine valve of the at least two engine valves, the body of each of the bridge pins being further configured to be received in a corresponding one of the slots while allowing vertical movement of the bridge pin within the slot, the vertical movement of the bridge pin being limited by contact of the end cap with the arm of the corresponding slot.

2. 2. The valve actuation assembly of claim 1, wherein a first engine valve of the at least two engine valves is actuated by an auxiliary rocker arm via a corresponding one of the bridge pins, the valve actuation assembly further comprising an upper surface formed on the valve bridge body having a height such that when the valve bridge is in an uncontrolled state for the at least two engine valves, the upper surface contacts a surface of the auxiliary rocker arm to resist uncontrolled movement of the valve bridge.

Images