CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. Prov. App. No. 63/326,321, filed April 1, 2022, which is hereby incorporated by reference as if reproduced in its entirety

BACKGROUND

The present disclosure relates generally to variable valve actuation and, more particularly, to an improved two-plunger capsule with an integrated check valve.

Internal combustion engines typically use either a mechanical, electrical, or hydromechanical valve actuation system to actuate the engine valves. These systems may include a combination of camshafts, rocker arms and push rods that are driven by the engine's crankshaft rotation. In a typical valvetrain assembly used with a compression engine brake, the exhaust valve is actuated by a rocker arm which engages the exhaust valve by means of a valve bridge. The rocker arm rocks in response to a cam on a rotating cam shaft and presses down on the valve bridge which itself presses down on the exhaust valve to open it.

BRIEF DESCRIPTION OF THE DRAWINGS

The following figures are included to illustrate certain aspects of the present disclosure and should not be viewed as exclusive embodiments. The subject matter disclosed is capable of considerable modifications alterations combinations, and equivalents in form and function, without departing from the scope of this disclosure.

FIG. 1 illustrates a perspective view of a valve train assembly incorporating a rocker arm assembly that includes an intake rocker arm assembly and a combined exhaust rocker arm assembly and engine brake rocker arm assembly, according to one or more aspects of the present disclosure.

FIG. 2 illustrates a cross-sectional view of the combined rocker arm assembly shown in FIG. 1, according to one or more aspects of the present disclosure.

FIGs. 3A-3E illustrate cross-sectional views of an engine brake capsule assembly of the combined rocker arm of FIG. 2 transitioning between a drive mode and an engine brake mode, according to one or more aspects of the present disclosure.

FIG. 4 illustrates a cross-sectional view of another embodiment of an engine brake capsule assembly of the combined rocker arm of FIG. 2, according to one or more aspects of the present disclosure. DETAILED DESCRIPTION

Illustrative embodiments of the present invention are described in detail herein. In the interest of clarity, not all features of an actual implementation may be described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions may be made to achieve the specific implementation goals, which may vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time consuming but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of the present disclosure.

Throughout this disclosure, a reference numeral followed by an alphabetical character refers to a specific instance of an element and the reference numeral alone refers to the element generically or collectively. Thus, as an example (not shown in the drawings), widget "la" refers to an instance of a widget class, which may be referred to collectively as widgets " 1 " and any one of which may be referred to generically as a widget " 1". In the figures and the description, like numerals are intended to represent like elements.

The terms “couple” or “couples,” as used herein, are intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect electrical connection or a shaft coupling via other devices and connections.

To facilitate a better understanding of the present disclosure, the following examples of certain embodiments are given. In no way should the following examples be read to limit, or define, the scope of the disclosure. Embodiments described below with respect to one implementation are not intended to be limiting.

With initial reference to FIGs. 1 and 2, a valvetrain assembly constructed in accordance to one example of the present disclosure is shown and generally identified at reference 10. The valvetrain assembly 10 utilizes engine braking and is shown for use in a four-cylinder engine, but it will be appreciated the features described herein may be used in any valvetrain assembly that utilizes engine braking. Without limitations, type III or type IV engine layouts may utilize valvetrain assembly 10. The valvetrain assembly 10 may be supported in a valvetrain carrier 12 and can include two rocker arms per cylinder.

Specifically, each cylinder may include an intake valve rocker arm assembly 14, an exhaust rocker arm assembly 16, and an engine brake rocker arm assembly 18. However, as illustrated, the exhaust valve rocker arm assembly 16 and the engine brake rocker arm assembly 18 may be combined into a single rocker arm and are collectively referred to as a combined exhaust and engine brake rocker arm assembly 20, which cooperates to control opening of both of the exhaust valves. The present disclosure is not limited to such embodiments and may include separate rocker arm assemblies for the exhaust rocker arm assembly 16 and engine brake rocker arm assembly 18. The intake valve rocker arm assembly 14 may be configured to control motion of the intake valves, the exhaust valve rocker arm assembly 16 may be configured to control exhaust valve motion in a drive mode, and the engine brake rocker arm assembly 18 may be configured to act on one of the two exhaust valves in an engine brake mode, as will be described herein.

A rocker shaft 22 may be received by the valvetrain carrier 12 and may support rotation of the combined exhaust and engine brake rocker arm assembly 20. As described herein, the rocker shaft 22 may communicate oil to the assemblies 16, 18 during operation. A cam shaft 24 may include lift profiles or cam lobes configured to rotate assemblies 16, 18 to activate first and second exhaust valves 26 and 28, as is described herein in more detail. For example, FIG. 2 illustrates cam shaft 24 with an exhaust event lift profile or lobe 30 and a brake event lift profile or lobe 32, which may respectively cause combined rocker arm assembly 20 to operate in a drive mode and an engine brake mode.

The combined exhaust and engine brake rocker arm assembly 20 may generally include a rocker arm body 40, an axle 42, and a roller 44. The rocker arm body 40 may include an exhaust rocker arm portion 46, and an engine brake arm portion 48. Rocker arm body 40 may receive the rocker shaft 22 and defines a pair of flanges 50 to receive the axle 42 such that roller 44 is positioned at least partially therebetween. As such, the axle 42 may be coupled to the rocker arm body 40 and may receive the roller 44, which is configured to be engaged by the exhaust lift lobe 30 or engine brake lobe 32 of the cam shaft 24. This engagement of the roller 44 may cause combined rocker arm assembly 20 to rotate about rocker shaft 22 and engage a valve bridge assembly 52, as described herein in more detail.

The exhaust valve rocker arm assembly 16 may include exhaust rocker arm portion 46, which defines a bore 54 configured to at least partially receive a lost motion spigot assembly 56. When roller 44 is engaged by the exhaust lift profile 30, the exhaust rocker arm portion 46 and lost motion spigot assembly 56 may be rotated downward, causing downward movement of the valve bridge assembly 52, which engages the first and second exhaust valve 26 and 28 associated with a cylinder of an engine (not shown). The lost motion spigot assembly 56 may be configured to take up any lash between the lost motion spigot assembly 56 and the valve bridge assembly 52. In the example implementation, the lost motion exhaust spigot assembly 56 may generally include an e-foot 66 configured to engage with the valve bridge assembly 52.

With continued reference to FIG. 2, the engine brake arm portion 48 may define a bore 110 configured to at least partially receive an engine brake capsule assembly 112. When roller 44 is engaged by the engine brake lift profile 32, the engine brake rocker arm portion 48 and engine brake capsule assembly 112 may be rotated downward, causing downward movement of the valve bridge assembly 52, which engages only the first exhaust valve 26 (i.e. , not valve 28).

In the example embodiment, engine brake capsule assembly 112 may configured to selectively move from a collapsing mode to a rigid mode to selectively transfer cam motion to the first exhaust valve 26 during an engine braking event (i.e., engine brake mode). As illustrated, an e-foot included in the engine brake capsule assembly 112 may be configured to act against a valve pin 130, which is slidingly disposed within the valve bridge assembly 52, wherein the valve pin 130 is configured to transfer force to the first exhaust valve 26.

FIGs. 3A-3E illustrate a cross-sectional view of an improved engine brake capsule assembly 300 transitioning between a drive mode and an engine brake mode, according to one or more aspects of the present disclosure. The present disclosure contemplates usage of combined exhaust and engine brake rocker arm assembly 20 (referring to FIGs. 1-2) or solely a dedicated engine brake rocker arm assembly 18 (referring to FIGs. 1-2) with the engine brake capsule assembly 300. In previous embodiments, the engine brake capsule assembly 112 (referring to FIG. 2) may have remained in contact with the first exhaust valve 26 (referring to FIG. 2) when there is no active actuation of the engine brake capsule assembly 112 (for example, when the oil control valve is turned off or de-energized). The present embodiments of engine brake capsule assembly 300 may eliminate this issue by retracting the force-driving component (i.e., a plunger) within the rocker arm assembly.

The engine brake capsule assembly 300 may be configured to transition between a retracted position and an extended position, wherein in the retracted position the engine brake capsule assembly 300 does not engage a valve bridge (such as valve bridge assembly 52 illustrated in FIG. 2), and in the extended position, the engine brake capsule assembly 300 may selectively engage the valve bridge to open first exhaust valve 26 (referring to FIG. 2). The engine brake capsule assembly 300 may be any suitable size, height, shape, and any combinations thereof. Further, the engine brake capsule assembly 300 may comprise any suitable materials, such as metals, nonmetals, polymers, composites, and any combinations thereof.

The engine brake capsule assembly 300 may comprise a body 302, a first plunger 304, a second plunger 306, and a check ball valve assembly 308. In embodiments, the body 302 may be disposed within the bore 110 (referring to FIG. 2) of the engine brake arm portion 48 (referring to FIG. 2). The body 302 may be configured to house and/or contain the components of the engine brake capsule assembly 300. As illustrated, the body 302 may comprise a lower chamber 310 and an upper chamber 312. In embodiments, the upper chamber 312 may be disposed above and fluidly coupled to the lower chamber 310. The body 302 may be configured to receive hydraulic fluid supplied by the rocker shaft 22 (referring to FIGs. 1-2), wherein the rocker shaft 22 is disposed through the combined exhaust and engine brake rocker arm assembly 20. In the present embodiment, the body 302 may receive a flow of hydraulic fluid from the rocker shaft 22 through a first inlet 314. As illustrated, the body 302 may further comprise a first outlet 316, wherein both the first inlet 314 and the first outlet 316 may be fluidly coupled to the upper chamber 312. In embodiments, the hydraulic fluid may enter upper chamber 312 via first inlet 314 and exit via first outlet 316.

As illustrated, the first plunger 304 may be disposed within the body 302 and in at least a portion of the upper chamber 312 and the lower chamber 310. Abottom end 318 of the first plunger 304 may be coupled to a top end 320 of the second plunger 306, wherein the second plunger 306 may be disposed in the lower chamber 310 and define a bottom end 322 of the lower chamber 310. In embodiments, a retaining ring 324 may be used to secure and coupled the first plunger 304 to the second plunger 306. Without limitations, any other suitable component, fastener (i.e., c-clip), or coupling means (i.e., threading) may be used to couple the first plunger 304 to the second plunger 306. As the first plunger 304 and second plunger 306 are coupled together, the two-plunger system of the engine brake capsule assembly 300 may function as a singular plunger. For example, as the second plunger 306 is actuated to translate, the first plunger 304 may accordingly translate in conjunction with the second plunger 306.

In embodiments, the first plunger 304 may supply hydraulic fluid to the lower chamber 310. The first plunger 304 may comprise a second inlet 326 and a second outlet 328 located within the volume of the upper chamber 312 and both fluidly coupled with the upper chamber 312. The hydraulic fluid supplied to the upper chamber 312 may enter into an interior of the first plunger 304 via the second inlet 326 and flow down to the check ball valve assembly 308 disposed therein. In other embodiments wherein the engine brake capsule assembly 300 may be deactivated, hydraulic fluid may flow from an interior of the first plunger 304 out through the second outlet 328 into the upper chamber 312 and subsequently out via the first outlet 316.

The check ball valve assembly 308 may be disposed within the first plunger 304 and configured to selectively enable hydraulic fluid into the lower chamber 310 to cause translation of the first plunger 304 and the second plunger 306 from the retracted position to the extended position. As illustrated, the check ball valve assembly 308 may be configured to seat against an internal shoulder within the first plunger 304 and may be actuated to open by a force and/or by fluid pressure supplied from an upwards direction. Hydraulic fluid may be introduced into the first plunger 304, flow past the check ball valve assembly 308, and flow into the lower chamber 310 via ports 330 of the first plunger 304. The first plunger 304 may comprise one or more ports 330 configured to provide fluid communication between the interior of the first plunger 304 and the lower chamber 310. As hydraulic fluid is introduced into the lower chamber 310, the pressure acting upon the second plunger 306 may subsequently increase to cause the second plunger 306 to translate downwards, wherein the first plunger 304 translates in conjunction with the second plunger 306. A first spring 332 disposed in the upper chamber 312 and configured to bias the first plunger 304 upwards may be compressed as the first plunger 304 translates downwards. The first spring 332 may be disposed between a bottom end 334 of the upper chamber 312 and a protruding lip 336 of the first plunger 304 disposed at a top end 338 of the first plunger 304. The protruding lip 336 may extend out a distance laterally from the first plunger 304, creating a seat for the first spring 332.

The engine brake capsule assembly 300 may further comprise a seeger clip 340 disposed at a top end 342 of the body 302 and a cup housing 344 disposed underneath and adjacent to the seeger clip 340. The cup housing 344 may define a top end of the upper chamber 312 and may be configured to house a second spring 346. The second spring 346 may be disposed within the cup housing 344 and may be configured to expand and translate the cup housing 344 downwards in response to a decrease in pressure in the upper chamber 312 based on a reduction of the flow of the hydraulic fluid.

An actuation pin 348 may be disposed along an internal bottom side 350 of the cup housing 344 and may extend partially outwards and down from the cup housing 344 and into the first plunger 304. The second spring 346 may be disposed on top of the actuation pin 348 and below the seeger clip 340, wherein the seeger clip 340 may remain stationary and the second spring 346 may be configured to expand downwards. In embodiments, the actuation pin 346 may be configured to unseat and open the check ball valve assembly 308.

During operations of combined exhaust and engine brake rocker arm assembly 20, the engine brake capsule assembly 300 may be actuated to transition between drive mode and engine brake mode. During drive mode, the first spring 332 and the second spring 346 may first plunger 304 and cup housing 344 to an initial or first position. In the initial position shown in FIG. 3 A, the check ball valve assembly 308 is open as the actuation pin 348 may unseat the ball from the internal shoulder within first plunger 304, and there may be open fluid communication between the upper chamber 312 and lower chamber 310. Transitioning to the engine brake mode may include introducing a flow of hydraulic fluid into the engine brake capsule assembly 300. As hydraulic fluid is introduced to the engine brake capsule assembly 300 via first inlet 314, the hydraulic fluid may flow through upper chamber 312 and into first plunger 304 via second inlet 326. The hydraulic fluid may freely pass the check ball valve assembly 308 and flow through the ports 330 and into the lower chamber 310. The increasing pressure may force the second plunger 306, and subsequently the first plunger 304, to translate downwards into an extended position. As the first plunger 304 translates, the first spring 332 may be compressed by the protruding lip 336 of the first plunger 304, as best seen in FIG. 3B. In this state, the pressure within the upper chamber 312 may be sufficient to contain the cup housing 344 in its position, such that the second spring 346 does not extend. The check ball valve assembly 308 may return to a seated position once there is a negligible pressure differential between the upper and lower chambers 312, 310, such as when the second plunger 306 engages with the first exhaust valve 26 (referring to FIG. 2). For example, as the second plunger 306 engages with the first exhaust valve 26, the reaction force may increase the pressure within the lower chamber 310, thereby causing the check ball valve assembly 308 to close, as seen in FIG. 3C. The engine brake capsule assembly 300 may now be in the engine brake mode. The present disclosure contemplates operation of the combined exhaust and engine brake rocker arm assembly 20 including opening the first exhaust valve 26 with second plunger 306, wherein the engine brake capsule assembly 300 may be in a rigid mode to selectively transfer cam motion to the first exhaust valve 26 during an engine braking event.

As the combined exhaust and engine brake rocker arm assembly 20 transitions from the engine brake mode back to the drive mode, the hydraulic fluid supplied to the engine brake capsule assembly 300 decreases. As the pressure acting against the cup housing 344 decreases, the second spring 346 may expand and cause both the cup housing 344 and actuation pin 348 to translate downwards to engage with the check ball valve assembly 308, thereby opening the flow path out of the engine brake capsule assembly 300, as seen in FIG. 3D. In certain embodiments, the second spring 346 may be configured to solely move the cup housing 344. For example, as illustrated in FIG. 4, the actuation pin 348 may be integrated with the cup housing 344 to form a singular component of an engine brake capsule assembly 400. In this embodiment, the actuation pin 348 may be an extending protrusion rather than a separate component from the cup housing 344. The engine brake capsule assembly 400 may otherwise operate substantially similar to the engine brake capsule assembly 300 of FIGs. 3A-3E. With reference back to FIGs. 3A-3E, the unseated check ball valve assembly 308 may reduce the pressure within the lower chamber 310 and may direct the pressurized hydraulic fluid out of the lower chamber 310, through the first plunger 304, and out the upper chamber 312 via first outlet 316. As both the upper and lower chambers 312, 310 experience a reduction in pressure, the spring force of the first spring 332 may force the first plunger 304 to translate upwards. In embodiments, the spring force of the first spring 332 may be greater than that of the second spring 346, and the second spring 346 may therefore be compressed as the first plunger 304 forces the cup housing 344 upwards. Both the first plunger 304 and cup housing 344 may be back at the initial position, in the drive mode, as seen in FIG. 3E.

Therefore, the disclosed systems and methods are well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the teachings of the present disclosure may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered, combined, or modified and all such variations are considered within the scope of the present disclosure. The systems and methods illustratively disclosed herein may suitably be practiced in the absence of any element that is not specifically disclosed herein and any optional element disclosed herein. While compositions and methods are described in terms of "comprising," "containing," or "including" various components or steps, the compositions and methods can also "consist essentially of or "consist of the various components and steps. All numbers and ranges disclosed above may vary by some amount. Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range is specifically disclosed. In particular, every range of values (of the form, "from about a to about b," or, equivalently, "from approximately a to b," or, equivalently, "from approximately a-b") disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles "a" or "an," as used in the claims, are defined herein to mean one or more than one of the element that it introduces.