Patent Application
20240401508
The present disclosure relates generally to variable valve actuation and, more particularly, to an improved hydraulic capsule for variable valve actuation.
Internal combustion engines typically use either a mechanical, electrical, or hydro-mechanical 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. Existing engine brake actuators may experience impact loading and failure between a latch pin and seeger clip when pressurized during a braking mode.
In particular embodiments, a rocker assembly includes: a rocker arm including a valve end, the valve end including an actuator bore; and an engine brake capsule assembly in the actuator bore. The engine brake capsule assembly is movable between a retracted position and an extended position. In the retracted position the engine brake capsule assembly does not engage a valve bridge, and in the extended position the engine brake capsule assembly selectively engages the valve bridge to open a first exhaust valve. The engine brake capsule assembly includes: an outer housing including a lower chamber; a plunger defining a bottom end of the lower chamber, the plunger extends out below the outer housing; a check ball valve assembly disposed within the lower chamber configured to selectively enable a hydraulic fluid into the lower chamber to move the plunger from the retracted position to the extended position; an oil channel fluidly coupled to the lower chamber and configured to direct a flow of the hydraulic fluid out of the lower chamber during a transition from the extended position to the retracted position; and a spool valve configured to selectively block the oil channel.
In particular embodiments, the outer housing further includes a first bore disposed along a horizontal plane and configured to receive the hydraulic fluid from a rocker shaft. The rocker shaft is disposed through a center pivot bore of the rocker arm.
In particular embodiments, the lower chamber is fluidly coupled to the first bore. The check ball valve assembly is configured to allow the hydraulic fluid into the lower chamber as the hydraulic fluid is introduced into the first bore.
In particular embodiments, the spool valve is disposed within the first bore coupled to a spring disposed at an end of the first bore.
In particular embodiments, the rocker assembly further includes a plug disposed at the end of the first bore configured to seal the end of the first bore.
In particular embodiments, the spool valve is configured to compress the spring and translate along the first bore as a flow of the hydraulic fluid is introduced into the outer housing.
In particular embodiments, the spool valve is configured to block the oil channel and rest against the end of the first bore in response to an increase in pressure based on introduction of the hydraulic fluid.
In particular embodiments, the spring is configured to expand and translate the spool valve back along the first bore in response to a decrease in pressure based on a reduction of the flow of the hydraulic fluid, thereby opening the oil channel to reduce a pressure within the lower chamber.
In particular embodiments, the outer housing further includes an upper chamber having an inlet. The first bore is disposed between the upper chamber and the lower chamber. The oil channel fluidly couples the upper chamber and the lower chamber.
In particular embodiments, the outer housing further includes a central bore and a connecting pathway. The central bore is disposed along a central axis of the outer housing and fluidly couples the upper chamber and the lower chamber. The connecting pathway is disposed between the inlet and the first bore.
In particular embodiments, the inlet is configured to receive the hydraulic fluid from the rocker shaft and direct the hydraulic fluid into the upper chamber and to the first bore through the connecting pathway.
In particular embodiments, a valvetrain assembly includes: a first engine valve; a second engine valve; a valve bridge operatively associated with the first engine valve and the second engine valve; and a combined exhaust and engine brake rocker arm assembly configured to selectively open the first engine valve and the second engine valve. The rocker arm assembly includes: a rocker arm including a valve end, the valve end including a first actuator bore; and an engine brake capsule assembly in the first actuator bore. The engine brake capsule assembly is movable between a retracted position and an extended position. In the retracted position the engine brake capsule assembly does not engage the valve bridge, and in the extended position the engine brake capsule assembly selectively engages the valve bridge to open the first engine valve. The engine brake capsule assembly includes: an outer housing including a lower chamber; a plunger defining a bottom end of the lower chamber, the plunger extends out below the outer housing; a check ball valve assembly disposed within the lower chamber configured to selectively enable a hydraulic fluid into the lower chamber to move the plunger from the retracted position to the extended position; an oil channel fluidly coupled to the lower chamber and configured to direct a flow of the hydraulic fluid out of the lower chamber during a transition from the extended position to the retracted position; and a spool valve configured to selectively block the oil channel.
In particular embodiments, the outer housing further includes a first bore disposed along a horizontal plane and configured to receive the hydraulic fluid from a rocker shaft. The rocker shaft is disposed through a center pivot bore of the rocker arm.
In particular embodiments, the lower chamber is fluidly coupled to the first bore. The check ball valve assembly is configured to allow the hydraulic fluid into the lower chamber as the hydraulic fluid is introduced into the first bore.
In particular embodiments, the spool valve is disposed within the first bore coupled to a spring disposed at an end of the first bore.
In particular embodiments, the spool valve is configured to compress the spring and translate along the first bore as a flow of the hydraulic fluid is introduced into the outer housing.
In particular embodiments, the spool valve is configured to block the oil channel and rest against the end of the first bore in response to an increase in pressure based on introduction of the hydraulic fluid.
In particular embodiments, the spring is configured to expand and translate the spool valve back along the first bore in response to a decrease in pressure based on a reduction of the flow of the hydraulic fluid, thereby opening the oil channel to reduce a pressure within the lower chamber.
In particular embodiments, the outer housing further includes: an upper chamber including an inlet, the first bore is disposed between the upper chamber and the lower chamber, and the oil channel fluidly couples the upper chamber and the lower chamber; a central bore; and a connecting pathway. The central bore is disposed along a central axis of the outer housing and fluidly couples the upper chamber and the lower chamber. The connecting pathway is disposed between the inlet and the first bore.
In particular embodiments, the inlet is configured to receive the hydraulic fluid from the rocker shaft and direct the hydraulic fluid into the upper chamber and to the first bore through the connecting pathway.
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.
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 “1a” 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
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,
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
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.
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
The engine brake capsule assembly 300 may comprise an outer housing 302, a plunger 304, a check ball valve 306, an oil channel 308, and a spool valve 310. In embodiments, the outer housing 302 may be disposed within the bore 110 (referring to
The engine brake capsule assembly 300 may further comprise a plug 318 disposed at an end of the first bore 316 configured to seal that end, wherein an opposing end may be open and configured to receive a fluid. As shown, the spool valve 310 may be disposed within the first bore 316 operable to translate along a length of the first bore 316. The engine brake capsule assembly 300 may further comprise a spring 320 coupled to the plug 318, wherein the spool valve 310 may be disposed at an opposing end of the spring 320. The spool valve 310 may be operable to apply force against and compress the spring 320, and when there is a reduction in pressure, the spring 320 may be operable to expand and apply a force against the spool valve 310, thereby causing the spool valve 310 to move.
In embodiments, the first bore 316 may be configured to receive hydraulic fluid supplied by the rocker shaft 22 (referring to
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 spring 320 may bias the spool valve 310 to an initial or first position. In the illustrated initial position, the oil channel 308 is open, and there may be open fluid communication between the upper chamber 314 and lower chamber 312 through the oil channel 308. 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 inlet 324, a portion of the hydraulic fluid may flow through the connecting pathway 322 into the first bore 316. The increasing pressure may force the spool valve 310 to translate along the first bore 316 and compress the spring 320 to rest at a second position. At this second position, the spool valve 310 may block the oil channel 308. The hydraulic fluid may then be directed to flow from the upper chamber 314 through the central bore 326 and towards the lower chamber 312.
As illustrated, the check ball valve 306 may be disposed at an upper portion of the lower chamber 312 and seated against the intersection of the central bore 326 with the lower chamber 312. The check ball valve 306 may be configured to selectively allow hydraulic fluid into the lower chamber to move the plunger 304 from a retracted position to an extended position, wherein the plunger 304 defines a bottom end of the lower chamber 312. During the drive mode, the check ball valve 306 may remain seated against the aforementioned intersection as fluid communication was enabled via the oil channel 308. As the oil channel 308 is blocked in the engine brake mode, the increased pressure due to the hydraulic fluid may activate the check ball valve 306 and unseat the check ball valve, thereby allowing a flow of hydraulic fluid into the lower chamber 312. As pressure increases within the lower chamber 312, the plunger 304 may be actuated to translate downwards from a retracted position to an extended position. The check ball valve 306 may return to a seated position once there is a negligible pressure differential between the upper and lower chambers 312, 314 and when the plunger 304 engages with the first exhaust valve 26. For example, as the plunger 304 engages with the first exhaust valve 26, the reaction force may increase the pressure within the lower chamber 312, thereby causing the check ball valve 306 to close. Operation of the combined exhaust and engine brake rocker arm assembly 20 may now include opening the first exhaust valve 26 with plunger 304, 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 spool valve 310 decreases, the spring 320 may expand and cause the spool valve 310 to translate back to the initial, first position, thereby opening the oil channel 308. The opened oil channel 308 may reduce the pressure within the lower chamber 312 and may direct the pressurized hydraulic fluid out of the lower chamber 312, and the plunger 304 may return back to a retracted position.
Engine brake capsule assembly 500 may operate without an upper chamber, central bore, connecting pathway, and any combinations thereof. During operations, hydraulic fluid may be introduced directly into the outer housing 502 via the first bore 518. While in a drive mode, the spring 512 may be expanded, and the spool valve 510 may be disposed in a first position abutting a shoulder 520 within the first bore 518. At the first position, the spool valve 510 may be blocking access to the check ball valve 506 within the lower chamber 516. Further, the oil channel 508 may be open and provide fluid communication between the lower chamber 516 and an external component.
As the hydraulic fluid is introduced through the first bore 518 upon a transition to an engine brake mode, the spool valve 510 may be actuated to compress the spring 512 and to translate along the first bore 518, which may expose the check ball valve 506 to the introduced hydraulic fluid. As the pressure increases, the check ball valve 506 may be unseated (as best seen in
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 500 decreases. As the pressure acting against the spool valve 510 decreases, the spring 512 may expand and cause the spool valve 510 to translate back to the initial, first position against the shoulder 520, thereby opening the oil channel 508. The opened oil channel 508 may reduce the pressure within the lower chamber 516 and may direct the pressurized hydraulic fluid out of the lower chamber 516, and the plunger 504 may return back to a retracted position.
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.
This application claims the benefit under 35 U.S.C. § 365(c) of International Patent Application No. PCT/EP2023/025119, filed 15 Mar. 2023, which claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 63/319,870, filed 15 Mar. 2022, all of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63319870 | Mar 2022 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2023/025119 | Mar 2023 | WO |
| Child | 18802651 | US |
