Valve bridge with a concave chamber

Abstract

The valve bridge includes a central body and at least first and second valve interface portions extending from the central body, each of the at least first and second valve interface portions defining a chamber configured to receive an engine valve and a corresponding valve spring and spring retainer, each chamber includes a valve bridge control surface configured to selectively contact at least one of the corresponding valve spring and spring retainer, each valve bridge control surface being a concave surface configured to extend downwardly around the corresponding valve spring.

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 a 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 allows 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 the 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 normal lash settings) with the engine valve and the motion transmission component at the same time. In this way, the valve bridge is consistently maintained in alignment 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 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 an outer plunger 720 and engaged in 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 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.

[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, the 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, allowing the engine valve to rapidly accelerate to the closed position without restraint under the considerable force of the valve spring. 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 travel in an uncontrolled trajectory generally away from the engine valve until it hits a rocker arm or some other object. In fact, it is possible for the valve bridge to disengage from the tip of any 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 can occur as a result of the 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 for use with an engine valve assembly of an internal combustion engine, the engine valve assembly including 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. The valve bridge includes a central body and at least first and second valve interface portions extending from the central body, each of the at least first and second valve interface portions defining a chamber configured to receive one of the at least two engine valves and a corresponding one of the at least two valve springs and at least two spring retainers. Each chamber includes a valve bridge control surface configured to selectively contact at least one of the corresponding valve spring and spring retainer, each valve bridge control surface being a concave surface configured to extend downwardly around the corresponding valve spring. Each valve bridge control surface is configured to not contact the corresponding valve spring and spring retainer when the valve bridge is in a controlled state with respect to the at least two engine valves, and to contact the corresponding valve spring and spring retainer to resist an uncontrolled movement of the valve bridge when the valve bridge is in an uncontrolled state with respect to the at least two engine valves.

[0007] In one embodiment, the central body of the valve bridge includes a bore configured to receive a locking mechanism.

[0008] In one embodiment, each of at least the first and second valve interface portions extends laterally away from the central body and includes parallel side walls that define a corresponding chamber. Further, each valve bridge control surface is defined by the side walls and the inner surface of the central body. Preferably, for each chamber, the distal edge of the side wall relative to the central body extends beyond the longitudinal axis of the corresponding engine valve. Further, each chamber may be configured to open in a direction away from the central body.

[0009] In another embodiment, each of at least the first and second valve interface portions also includes an upper wall that defines a corresponding chamber. Each upper wall may include a receptacle configured to receive the valve stem tip of the corresponding engine valve.

Brief Description of the Drawings

[0010] 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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DETAILED DESCRIPTION OF THE INVENTION

[0011] FIGS. 2 to 41 illustrate various embodiments of a valve bridge system including a valve bridge guide according to the present disclosure. In all of the embodiments and variations illustrated in FIGS. 2 to 41, it is assumed that the valve bridge is of the type illustrated in FIG. 1, i.e., a valve bridge having a locking mechanism of the general type illustrated in FIG. 1 and described above.

[0012] Figure 2 illustrates a first embodiment according to the present disclosure in which an 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) can 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 an internal combustion engine.

[0013] 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 engine valve head engaged with a valve seat formed in the cylinder head 230), and valve spring retainers 209, 211 attached to the valve stems of the engine valves. As further shown, the valve bridge system 202 further includes a valve bridge guide 206 that extends downwardly (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, 210 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 formed in the valve bridge 204 and the valve bridge guide 206 (best shown in FIG. 3). 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.

[0014] FIG. 3 illustrates a cross-sectional view of the valve bridge guide 206 and the first valve spring 208 taken along section line III-III (as shown in FIG. 2). An opening 310 for accommodating the locking mechanism is formed in the valve spring guide 206, and FIG. 3 further illustrates a valve stem 320 disposed within the corresponding valve spring 208. More specifically, FIG. 3 illustrates two valve bridge control surfaces 402 defined by the valve bridge guide 206 such that the valve bridge control surface 402 conforms to the corresponding valve springs 208, 210 (only one is shown in FIG. 3), i.e., the valve bridge control surface 402 is concave with respect to the convex outer surfaces of the valve springs 208, 210. Although conforming, the valve bridge control surface 402 is configured such that during the controlled state of the valve bridge, the valve bridge control surface 402 (and thus the valve bridge guide 206) can avoid contact with their corresponding valve springs 208, 210. The valve bridge control surfaces 402 can be 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, valve bridge guide 206, and 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 account for the expected maximum change in spring diameter while remaining as close as possible to the valve springs 208, 210.

[0015] In some cases, it may not be desirable 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, it may be desirable instead to configure the valve bridge control surface 402 to contact the spring retainers 209, 211. 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 surface of the spring retainers 209, 211. Also in this case, such a concave surface is configured such that the valve bridge control surface 402 can avoid contact with their corresponding spring retainers 209, 211 during the controlled state of the valve bridge, and further, the normal movement and vibration of the valve bridge 204, valve bridge guide 206, and 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.

[0016] The various figures illustrated and described in this disclosure show at least two concave valve bridge control surfaces 402, but 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), a combination of a single valve bridge control surface 402 and the bridge pin may be sufficient.

[0017] 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, although only the valve spring 208 illustrated in FIG. 4 is described herein for ease of explanation, it 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 circumference 408 of the valve spring 208. In practice, the clearance between the valve bridge control surface 402 and the outer circumference 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 tolerance of the parts plus the 0.25 mm play allowed. Further, the chamfering of 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.

[0018] As further shown in FIG. 4, the circumferential length of the concave valve bridge control surface 402 (with respect to the outer circumference 408 of the spring 208) is bounded 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 circumference 408 of the valve spring 208. When configured in this way, any movement of the valve bridge guide 206 in any direction indicated by the line 410 (e.g., 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 circumference 408, whereby it is 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.

[0019] 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 in 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, even though it is 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 as 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.

[0020] Anyway, as further shown, the valve bridge guide 502 has an internally formed opening or aperture 602 configured to snugly receive portion 604 of the valve bridge 204. As shown, 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 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 comprises a hole that intersects the opening 602 formed in the valve bridge guide 502. Thus, at the location where the hole 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 portion 604 of the valve bridge 204 is also formed as a semi-circular channel in the outer wall surface of 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 portion 604 of the valve bridge 204. For example, in the illustrated embodiment, the fastener 612 may comprise a split dowel pin as shown, but those skilled in the art will recognize that other types of fasteners, such as screws, may 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) may 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 may also be employed as a design option.

[0021] 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 regard. However, in this embodiment, the valve bridge guide 702 extends inwardly from the side wall surface of the opening 602 and is configured with one or more teeth 802 adapted to engage a notch 804 formed in 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 in the side wall of the portion 604 of the valve bridge 204. When the teeth 802 engage 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 702 and the valve bridge 204 move together. Note 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.

[0022] 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 over 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.

[0023] 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 also formed in this case as a single unit 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, in this case as well, 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 1002, the valve bridge guide 902 is operably connected to the valve bridge 204 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.

[0024] Referring now to FIG. 11, a fourth variant of the valve bridge guide 1102 is shown. In this variant, 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 permits 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 bridge 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 1107, which 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, 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 described above. 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 will again resist uncontrolled movement and allow the valve bridge 204 to settle back onto the tip of the engine valve.

[0025] Referring now to FIG. 12, a fifth modification 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 modification 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 described above. Further, as shown, each of the projecting members 1204-1212 comprises attachment 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 attachment 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.

[0026] 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. As with 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). Further, 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 (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 an arm of the valve bridge 204.

[0027] 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 on top of 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 even if a vertical displacement is applied to the valve bridge 204, the valve bridge guide 1402 cannot lift completely off the spring retainers 209, 211. In addition to the central opening 1418 that allows passage of a portion of the valve bridge 204, the valve bridge guide 1402 also includes a plurality of protruding members 1408 - 1416 (four are shown in the illustrated example) similar to those illustrated in FIGS. 7, 8, 11, and 12. As shown, the protruding members 1408 - 1416 are formed as upwardly bent portions of the horizontal plane 1404, resulting in openings 1426, 1428 that allow passage of the tips of the engine valves 1502. In this case, the protruding members 1408 - 1416 also define valve bridge control surfaces 1422, 1424 here to resist uncontrolled movement of the valve bridge 204.

[0028] FIG. 16 illustrates an isometric view of an eighth variation of a first main embodiment, which includes two guide members 1603 (only one is shown) configured such that a valve bridge guide 1602 engages both sides of a valve bridge 204 (not shown). Each guide member 1603 is formed as a punched sheet metal structure having a horizontal plane 1604 and a continuous side wall 1606 extending downward therefrom, as in the embodiments of FIGS. 14 and 15, but is configured to rest only on a single spring retainer 209. Again, 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 the valve bridge 204.

[0029] 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 sidewalls 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 1703 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 1714 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.

[0030] 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, although here too it is possible for each valve bridge to actuate more than three 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 valve and an upper surface 1904 opposite the lower surface 1902.

[0031] As further shown in this second main embodiment, the valve bridge system further includes a valve bridge guide in the form of a first member 1802 having a first surface 1906 facing the upper surface 1904 of the valve bridge 204. Using suitable fasteners 1806 (such as bolts threaded 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 1802 at a predetermined distance 1908 from the upper surface 1904 of the valve bridge 204 when at least two valve bridges 204, 212 are maintained in the closed state. Further, as shown, the first fixed position of the first member 1802 is aligned with a 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 in this manner across the valve bridges 204, 212 of a plurality of cylinders of the internal combustion engine, or can include a plurality of such first members 1802 if the cylinder configuration precludes the use of a single first member 1802.

[0032] 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 204 outside its normal range of movement when operating in a controlled state. Thus, a plurality of variations of the first embodiment illustrated in FIGS. 2-12 may resist movements that can cause the inclination or rotation of the valve bridge 204 with respect to the engine valves, but the first member 1802 resists 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 less than the depth 2002 of the receptacle 2004.In this way, when the valve bridges 204, 212 operate in an uncontrolled state, before the valve bridges 204, 212 can move a distance exceeding the depth 2002 of the receptacle 2004, they contact the first member 1802; 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), whereby that portion of the valve bridge 204 can be engaged with an external engine valve (i.e., the one farthest from the rocker shaft) and lifted slightly upward, for example, by about 1 - 2 mm. Thus, the predetermined distance 1908 should be selected to accommodate this possibility in order to avoid unwanted contact with the valve bridge 204. Additionally, normal wear of the engine valve seat can cause the tip 2006 of the engine valve to rise over time, and the predetermined distance 1908 must also account for this possibility.

[0033] 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 explained 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 closest to the rocker shaft 1808. Further, as best shown in FIGS. 18 and 19, the second member 1804 can be formed as an integral structure with the rocker pedestal 1810. In this way, the first and second members 1802, 1804 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.

[0034] 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, as is known in the art, by the use of a bridge pin 2102 that allows the application of auxiliary valve actuation motion to a single engine valve and also 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 2102 passing through the valve bridge 212 effectively functions as a second member 1804 that defines a valve bridge guide. That is, when the valve bridge 212 operates in an uncontrolled state, the presence of the bridge pin 2102 (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 2102. 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 in FIG. 21), the combined action of the first and second members 1802, 1804 resists uncontrolled movement of the valve bridge 212, particularly upward movement.

[0035] Figure 22 illustrates a first variant of a second embodiment in which the valve bridge guide comprises a first member 2202 formed as a three-sided arch or “strap”. Similar to the embodiments of FIGS. 18-21, the variant 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 204. 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 204 to the bases 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 204 (i.e., when the engine valve is fully closed) and above the upper surface 1904 of the valve bridge 204, 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 204 (e.g., referring to FIG. 1, the outer plunger 720 / cap 730) to contact the rocker arm 2212 as shown. Thus, in this variant, the displacement of the valve bridge 204 is constrained by the third side 2206 of the first member 2202 and the opening 2210 formed therein.

[0036] 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. Next, the bridge pin 2308 is received within a through hole 2310 formed within the valve bridge body 2302 and aligned with the first engine valve 2306, thereby allowing 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 the second engine valve 2304 and receive the stem of the second engine valve 2304. In FIG. 23, the valve bridge 2302 is depicted as being in an uncontrolled state, as illustrated by the receptacle 2314 losing contact with the second engine valve 2304. This results from the fact that there is no surface provided to suppress the upward movement of the valve bridge 2302 during the uncontrolled state.

[0037] Figure 24 illustrates a valve bridge according to a third main embodiment, showing a valve bridge substantially similar to that depicted in Figure 23. However, in this case, the valve bridge also has a through-hole 2404 formed therein and includes a bridge pin boss 2402 having a greater longitudinal length (or height) compared to the embodiment illustrated in Figure 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 causes 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 Figure 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.

[0038] 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 2414 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 up to the point of contact with 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.

[0039] 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 hole 2502 and the outer diameter of the bridge pin 2504. In particular, by tightly controlling and minimizing the clearance between the through hole 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 hole 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.

[0040] FIG. 25 further illustrates the fifth main embodiment in the range 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.

[0041] Furthermore, FIG. 25 further illustrates a sixth main embodiment in terms of showing the features of the extended valve stem. In the illustrated embodiment, the feature of the extended valve stem takes the form of a bridge pin 2512 present in the second through hole 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. Regardless of 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.

[0042] 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 aligns 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. Although the slot 2608 is illustrated in FIGS. 26-28 as extending laterally away from the valve bridge body 2602, this is not a requirement. For example, the slot 2608 may 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.

[0043] 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 extends toward and below at least one spring retainer 2910 and away from the protrusion 2904 such that a hook or latch feature 2906 extends beyond the outer periphery of 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, preventing 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 rim of protruding material that extends beyond the outer periphery of the corresponding valve spring 2914. In this way, the hook feature 2906 engages better with the spring retainer 2910, thereby better ensuring resistance to disengagement of the valve bridge.

[0044] As further shown in FIG. 29, the peripheral shape 2916 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, as 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.

[0045] 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 that extend within the valve body 3002 and are 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 stem 3012. As shown, each of the bridge pins 3008, 3010 has a spool-like shape with 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 bodies 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 experiences uncontrolled movement, the restraint placed on the valve bridge body 3002 by the bridge pins 3008, 3010 prevents disengagement from the engine valve stems 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 may 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.

[0046] Figure 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 a 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 cause disengagement in some cases.

[0047] 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 comprises 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.

[0048] 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 comprises an upward facing surface 3310. In the case of a sudden rearward rotation, the upward 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.

[0049] 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) the valve bridge body 3402 is provided. As shown, the valve bridge guide 3404 extends along 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 shaped 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 downwardly 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 downwardly below the lower surface 3502 as shown.

[0050] FIG. 36 illustrates the valve bridge and 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 the lateral portions outside the 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 during normal (i.e., controlled) operation of the valve bridge, no contact occurs between the half-cylinder wall and the valve spring retainer 3602 or the corresponding valve spring 3604. On the other hand, the radius of the half-cylinder wall is further configured such that during an uncontrolled state of the valve bridge body 3402, the half-cylinder wall contacts the valve spring retainer 3602 but avoids contact with the valve spring 3604. 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 valve bridge guide 3404 (preferably rather than the valve spring 3604).

[0051] FIG. 37 illustrates a twelfth embodiment of a valve bridge 3702 according to the eleventh embodiment. In this embodiment, the valve bridge 3702 includes a central body 3704 having first and second valve interface portions 3706 extending away from the central body 3704. As best shown in FIG. 40, the central body 3704 includes a bore 4004 configured to receive a locking mechanism 4002 that is substantially similar to the locking mechanism 606 illustrated in FIG. 6 and illustrated and described in connection with FIG. 1. The first and second valve interface portions 3706 preferably extend away from the central body 3704 and face each other. Although two valve interface portions 3706 are shown, it is understood that additional valve interface portions may be used. Preferably, the central body 3704 and the first and second valve interface portions 3706 are formed as an integral, single unit. As will be described in more detail below, each of the first and second valve interface portions 3706 is configured to receive at least a portion of an engine valve and its corresponding valve spring and valve spring retainer.

[0052] Each of the first and second valve interface portions 3706 is provided with a chamber 3708 configured to receive an engine valve and its corresponding valve spring and valve spring retainer. Referring to FIGS. 38 and 39, each chamber 3708 extends downwardly, i.e., toward the engine valve 3804. As further shown, each chamber 3708 is open in a direction away from the central body 3704, thereby allowing the corresponding engine valve, valve spring, and valve spring retainer to be received without completely surrounding these components. Each chamber 3708 is bounded by a concave valve bridge control surface defined by inner surfaces 3710, 3712, 3714 provided by the central body 3704 respectively and side walls 3716, 3718 that extend laterally and are (within manufacturing tolerances) substantially parallel. In practice, as shown in FIG. 37, the central body and side walls 3716, 3718 define an "H" shape. Each chamber 3708 is further bounded by an upper wall 3720 that surrounds each respective chamber 3708 from above. Each chamber further includes a receptacle 3722 formed in the inner surface of the upper wall 3720 and configured to receive the tip of the engine valve stem, as best illustrated in FIGS. 40 and 41. As shown in FIGS. 37 and 40, the first receptacle 3722a of the receptacles is configured to be substantially circular in shape to match (within manufacturing tolerances) the outer diameter of the tip of the engine valve, whereas the second receptacle 3722b of the receptacles is configured to have an elongated slot-shaped outer profile to accommodate the compliance or deflection of the engine valve stem relative to each other.

[0053] Referring to FIGS. 38-41, valve bridge 3702 is illustrated in conjunction with engine valve assembly 3802. In these figures, note that portions of the locking mechanism 4002, specifically outer plunger 3820 and cap 3822, extend outwardly from a hole 4004 formed in central body 3704. In the illustrated example, engine valve assembly 3802 includes a pair of engine valves 3804, each having a corresponding valve spring 3806, spring retainer 3808, and spring guide 3810, as is known in the art. Similar to a conventional valve bridge, valve bridge 3702 sits on top of engine valves 3804. As shown, at least a portion of each valve spring 3804, as well as its corresponding valve spring 3806 and spring retainer 3808, are received within a corresponding one of chambers 3708 such that the tip of each valve 3804 is received within a corresponding one of receptacles 3722, as best shown in FIGS. 40 and 41. In the presently preferred embodiment, the lateral length of side walls 3716, 3718 remote from central body 3704 is such that distal edges 3902, 3904 of side walls 3716, 3718 extend beyond the longitudinal axis of engine valves 3804. This example is illustrated particularly in FIG. 38, where distal edge 3902 of first chamber 3708a extends beyond longitudinal axis 3812 of first engine valve 3804a by a distance D, which can be selected as a matter of design choice.

[0054] As best shown in FIGS. 40 and 41, the dimensions of the inner surfaces 3710, 3712, 3714 are selected to provide clearance from the respective valve springs 3806 and spring retainers 3808 such that during operation of the valve bridge 3702 in a controlled state, the valve bridge control surfaces defined by the inner surfaces 3710, 3712, 3714 do not contact the respective valve springs 3806 and spring retainers 3808. Conversely, when the valve bridge is in an uncontrolled state, one or more of the inner surfaces may contact either or both of the corresponding valve springs 3806 and spring retainers 3808, thereby minimizing and / or eliminating the uncontrolled movement of the valve bridge. For example, unlike the embodiments illustrated in FIGS. 3 and 4 where the valve bridge control surface 402 is configured to reflect the curvature of the corresponding valve spring and / or spring retainer, the valve bridge control surfaces defined by the inner surfaces 3710, 3712, 3714 do not necessarily match the curvature of the valve spring and / or spring retainer, although it is possible to configure any one or more of these surfaces 3710, 3712, 3714 to match the curvature of the valve spring and / or spring retainer.

[0055] As described above, the present disclosure describes various embodiments and variations of valve bridge guides that can be used to resist, i.e., prevent, minimize, or accommodate, the uncontrolled movement of a 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. A valve bridge for use with an engine valve assembly of an internal combustion engine, wherein the engine valve assembly comprises 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, the valve bridge comprising: a central body; at least first and second valve interface portions extending from the central body, each of the at least first and second valve interface portions defining a chamber configured to receive one of the at least two engine valves and including two parallel side walls extending laterally away from the central body; and each chamber comprising a concave valve bridge control surface defined by the two parallel side walls and an inner surface of the central body, the concave valve bridge control surface being configured to selectively contact at least one of the corresponding valve spring and spring retainer; each chamber being open in a direction away from the central body; each valve bridge control surface being configured to extend downwardly around the corresponding valve spring and spring retainer; each valve bridge control surface being configured not to contact the corresponding valve spring and spring retainer when the valve bridge is in a controlled state with respect to the at least two engine valves; and each valve bridge control surface being configured to contact the corresponding valve spring and spring retainer to resist an uncontrolled movement of the valve bridge when the valve bridge is in an uncontrolled state with respect to the at least two engine valves.

2. The valve bridge according to claim 1, wherein the central body comprises a hole configured to receive a locking mechanism.

3. The valve bridge according to claim 1, wherein for each chamber, distal edges of the two parallel side walls of each chamber extend beyond a longitudinal axis of the corresponding engine valve.

4. The valve bridge according to claim 1, wherein each of the at least first and second valve interface portions includes an upper wall. **Claim 5** The valve bridge according to claim 4, wherein each upper wall includes a pocket configured to receive a valve stem tip of the corresponding engine valve.

Images