The instant disclosure relates generally to systems for actuating one or more engine valves in an internal combustion engine. In particular, embodiments of the instant disclosure relate to systems and methods for valve actuation using a lost motion system in the form of a collapsing valve train component, such as a collapsing valve bridge.
As known in the art, engine valve actuation is required in order to operate an internal combustion engine in a positive power generation mode. Further, auxiliary valve actuation motions (as opposed to “main” valve actuation motions used to operate in positive power generation mode) are known in the art that allow an internal combustion engine to operate in variations of positive power generation mode (e.g., exhaust gas recirculation (EGR)) or in other modes of operation, such as engine braking in which the internal combustion engine is operated essentially as an air compressor to develop retarding power to assist in slowing down the vehicle. Further still, variants in valve actuation motions used to provide engine braking are known (e.g., brake gas recirculation (BGR), bleeder braking, etc.)
To facilitate operation of an internal combustion engine in either positive power or engine braking modes, the use of lost motion components is also known in the art. Such lost motion components typically alter their length or engage/disengage adjacent components within a valve train to permit certain potentially-conflicting valve actuation motions, which are otherwise dictated by fixed-profile valve actuation motion sources such as rotating cams, to be “lost,” i.e., not conveyed via the valve train. A particular type of lost motion component known in the art are so-called collapsing (or, alternatively, locking) valve bridges. Examples of such components are taught in U.S. Pat. Nos. 8,936,006, 9,790,824 and European Patent No. 2975230. The subject matter of all of these documents is incorporated herein by reference. In these devices, locking elements are provided that permit a sliding plunger or similar element, disposed within a housing (such as within a centrally-located bore of a valve bridge), to be selectively unlocked (in which case the plunger is free to slide within the bore thereby permitting valve actuation motions applied to the plunger to be lost) or locked (in which case the plunger is maintained in a fixed position relative to the valve bridge thereby permitting valve actuation motions to be conveyed through the plunger to the housing).
While collapsing or locking valve bridges (or other valve train components) operate well for their intended purpose, various improvements thereto would be a welcome addition in the art. More specifically, improvements providing ease of assembly, lower manufacturing cost and more dependable and durable operation of collapsing valve train components, such as collapsing valve bridges, would contribute to the state of the art. It would therefore be advantageous to provide systems that address the aforementioned shortcoming and others in the prior art.
Responsive to the foregoing challenges, the instant disclosure provides various embodiments of valve actuation systems with features for facilitating locking and unlocking of a collapsing valve train components, such as a valve bridge.
According to aspects of the disclosure, a device for controlling motion applied to the one or more engine valves comprises a housing disposed within the valve train, the housing including a housing bore and at least one housing locking surface, a piston disposed within the housing bore, the piston having a piston bore and at least one locking pin receptacle defined therein, the at least one locking pin receptacle having a cylindrical shape, a locking assembly for selectively locking the piston to the housing, the locking assembly comprising an actuator pin supported for movement within the piston bore and at least one respective locking pin disposed in the at least one locking pin receptacle, the actuator pin including an outer locking pin engagement surface adapted to support the at least one locking pin in an extended position, and an inner locking pin support surface adapted to support the at least one locking pin in a retracted position, whereby movement of the actuator pin causes the at least one locking pin to selectively engage or disengage the housing locking surface thereby selectively locking or unlocking the piston relative to the housing.
According to one example implementation, a valve actuation system may include a collapsing valve bridge including a housing having a housing bore or cavity. A bridge piston is disposed in the housing bore and a locking assembly is disposed in the bridge piston for selectively locking and unlocking the piston for movement relative to the housing. A transverse bore, which may be generally cylindrical in shape and thus easily machined, may extend within the bridge piston and defines receptacles for locking pins of the locking assembly. A locking pin extension spring provides a biasing force on the locking pins tending to force the locking pins in a radially outward direction. Inward travel of the locking pins is limited by an inward travel limiting component, which may be a locking pin inner limit snap ring disposed centrally within the transverse bore. Outward travel of the locking pins may be limited by an outward travel limiting component, which may be in the form of a locking pin outer limit snap ring. The locking pins may include an undercut face on a radially outer surface, which may engage the outer limit snap ring. The undercut face may define a conical surface that engages a corresponding surface in an annular recess of the housing to ensure thorough engagement and load distribution when the piston is locked to the housing. Owing to the cylindrical shape, the locking pins may undergo some degree of rotation within their housings to facilitate alignment. The outer limit snap ring facilitates quick and easy installation of the locking assembly in the bridge piston and prevents significant rotation of the locking pins within the locking pin receptacles. The locking pins may be selectively actuated by control of hydraulic fluid provided through a piston fluid passage in the bridge piston which is in fluid communication with an annular channel formed in the housing bore. When pressurized hydraulic fluid is provided to the piston fluid passage and annular channel an inward force will be presented on radially-outermost surface of the locking pins and force them into a retracted position within the locking pin receptacles, thereby unlocking the bridge piston relative to the housing.
According to another example implementation, a bridge piston includes an actuation pin, which interacts with locking pins to provide synchronized motion and positive positioning thereof in locking and unlocking operations of a valve bridge piston within a valve bridge housing. The housing includes an internal bore in which is positioned a bridge piston for sliding movement relative thereto. Locking pins may be disposed in a transverse cylindrical bore extending through the piston. The piston includes an actuator pin bore for slidably receiving the actuator pin. Hydraulic fluid is conveyed through a fluid passage in a bridge piston cap to an upper surface of the actuator pin to cause downward movement thereof. A return spring returns the actuator pin to an upper indexed position in the absence of fluid pressure. The actuator pin includes an outer locking pin engagement surface for supporting the locking pins in an extended or deployed position in which they engage an annular recess in the bridge housing. The actuator pin also includes an inner locking pin engagement surface for supporting the locking pins in a retracted position. At least one transition surface on the actuating pin may be conical in shape and may extend from the outer locking pin engagement surface to the inner locking pin engagement surface. The locking pins may include an actuating pin interface with alignment surfaces for engaging the actuator pin and for aligning and preventing rotation of the locking pins in the deployed position, in the retracted position and during movement between the deployed and retracted positions. The alignment surfaces may include one or more conical chamfers on the locking pins adapted to cooperate with the transition surface(s) as the locking pin moves inward toward the actuation pin and to ultimately engage the transition surface of the actuating pin to provide for stable support of the locking pin in the retracted position. One or more conical surfaces on a housing interface of the locking pins may engage corresponding surfaces in an annular recess of the housing to ensure thorough engagement and load distribution when the piston is locked to the housing.
According to yet another example implementation, collapsing valve bridge locking pins comprise an actuation pin interface having a first concave surface for engaging the actuator pin outer locking pin engagement surface and a pair of conical chamfered surfaces for engaging respective transition surfaces on the actuator pin. A housing interface on the locking pins includes an outer convex surface and pair of opposed, symmetrical conical convex surfaces on top and bottom portions of the locking pins for providing effective engagement with one or more correspondingly shaped conical surfaces on an annular recess of the housing.
According to yet another example implementation, collapsing valve bridge locking pins may comprise an actuation pin interface having a first concave surface for engaging the actuator pin outer locking pin engagement surface and a single conical chamfered surface on an upper portion of the locking pin for engaging a transition surface on the actuation pin. A housing interface on the locking pins includes an outer convex surface and a single conical convex surface on a top portion of the locking pin.
According to yet another example implementation, collapsing valve bridge locking pins may comprise an actuation pin interface having a first concave surface for engaging the actuator pin outer locking pin engagement surface and a two, opposed, asymmetrical, conical chamfered surfaces on an upper and lower portion of the locking pin for engaging respective transition surface on the actuation pin. The asymmetrical conical chamfered surfaces prevent the locking pin from properly seating against the actuation pin inner locking pin engagement surface when the locking pin is upside down or improperly oriented, thus preventing improper assembly of the locking pin in the piston transverse bore. A housing interface on the locking pins includes an outer convex surface and an undercut portion forming a conical surface for engaging a correspondingly shaped conical surface on the piston bore annular recess. The undercut housing interface on the locking pin provides advantageous alignment and load distribution relative to the piston bore annular recess.
Other aspects and advantages of the disclosure will be apparent to those of ordinary skill from the detailed description that follows and the above aspects should not be viewed as exhaustive or limiting. The foregoing general description and the following detailed description are intended to provide examples of the inventive aspects of this disclosure and should in no way be construed as limiting or restrictive of the scope defined in the appended claims.
The above and other attendant advantages and features of the invention will be apparent from the following detailed description together with the accompanying drawings, in which like reference numerals represent like elements throughout. It will be understood that the description and embodiments are intended as illustrative examples according to aspects of the disclosure and are not intended to be limiting to the scope of invention, which is set forth in the claims appended hereto. In the following descriptions of the figures, all illustrations pertain to features that are examples according to aspects of the instant disclosure, unless otherwise noted.
As illustrated schematically in
According to aspects of the disclosure, a locking assembly 260 may be disposed in the bridge piston 240 for selectively locking and unlocking the piston 240 for movement relative to the housing 210. A transverse or radially-extending bore 241, which may be generally cylindrical in shape and thus easily formed, may extend within the bridge piston 240 and thus may provide respective, axially aligned locking pin housings or receptacles. Locking assembly 260 may include a pair of opposed locking pins 262 disposed in the transverse bore 241. A locking pin extension spring 264 may be provided in the transverse bore 241 between the two locking pins 262 and may provide a biasing force on the locking pins tending to force the locking pins in a deployed or locking direction radially outward from the axis or center of the bridge piston 240. Each locking pin 262 may include a recessed spring seat 261 formed on an inner surface thereof to engage the spring 264. Inward travel of the locking pins 262 may be limited by an inward travel limiting component, which may be in the form of a locking pin inner limit snap ring 266 disposed centrally within the transverse bore. Locking pin inner limit snap ring 266 may thus also serve to minimize any potential for one of the locking pins 262 to be fully retracted while the other locking pin is only partially retracted.
Outward travel of locking pins 262 may be limited by an outward travel limiting component, which may be in the form of a locking pin outer limit snap ring 270 disposed in a retaining groove 243 and having an outer diameter that substantially matches that of the bridge piston. As will be recognized, locking pins 262 may include an undercut face 263 on an outer surface thereof, which, in addition to providing advantages in engaging and locking the bridge piston to the housing 210, as will be detailed further herein, may engage the outer limit snap ring 270 when installed in groove 243 to define an outer travel limit of the locking pins 262. As will be recognized, outer limit snap ring 270 facilitates easy assembly of the locking pins 262 within the bridge piston 240. The inner limit snap ring 266, spring 264 and locking pins 262 may be installed in transverse bore 241 and held in a retracted position manually or with manufacturing equipment while the outer limit snap ring 270 may be fit onto the bridge piston 240 and positioned into groove 243. The outer limit snap ring 270 facilitates quick and easy installation of the locking assembly 260 in the bridge piston 240 and also serves as a locking pin travel limiting component to provide an outer limit on the travel of the locking pins 262. Still further, the outer limit snap ring prevents significant rotation of the locking pins 262 within the locking pin receptacles 241 and thus operate to maintain the locking pins 262 in a proper orientation.
Locking pins 262 may be selectively actuated by control of hydraulic fluid provided to the collapsing piston bridge 200. A piston fluid passage 245 may be provided in the bridge piston 240 and may receive hydraulic fluid via a hydraulic fluid source and passages in the valve train, such as the passage 152 in the swivel foot 150 (
When the piston is installed in the piston bore 212, outlet 247 may be in fluid communication with an annular channel 216 formed within the lateral surface of the piston bore 212. Locking pins may be controlled through application of pressurized hydraulic fluid in the piston fluid passage and annular channel 216. When pressurized hydraulic fluid is provided to the piston fluid passage 245 and annular channel 216, for example, by way of a control solenoid, as is generally known in the art, controlling fluid in the hydraulic passages in the valve train, an inward force will be presented on radially-outermost surface of the locking pins 262 and will be sufficient to overcome the bias of the locking pin extension spring 264. Consequently, the locking pins 262 will be forced into a retracted position within the locking pin receptacles 241 and out of contact with the annular channel 216, thereby unlocking the bridge piston 240 relative to the housing 210 and permitting the piston 240 to move within the housing bore 212, with the corresponding loss of motion in the valve train. Piston 240 may include a piston vent passage 249, which may vent hydraulic fluid from within the transverse bore 241 to the bottom of the housing bore 212. A housing vent passage 218 permits vented hydraulic fluid to exit the bottom of the housing 210. This arrangement prevents the buildup of hydraulic fluid in the transverse bore 241 behind (i.e., on the radially inward surfaces of) the locking pins 262.
As will be recognized from the instant disclosure, when the piston fluid passage 245 is not charged with pressurized hydraulic fluid, for example, when the control solenoid valve shuts off the flow of hydraulic fluid, bias of the piston return spring 250 may cause the bridge piston 240 to index upward within the housing bore 212 until the transverse bore 241 registers with the annular channel. At that point, the bias of the locking pin extension spring 264 is sufficient to cause the locking pins 262 to extend into the annular channel 216, thereby locking the bridge piston 240 relative to the housing 210.
As can best be seen in
According to aspects of the disclosure, a locking assembly 460 may be disposed in the bridge piston 440 for selectively locking and unlocking the piston 440 for movement relative to the housing 410. A transverse or radially-extending bore 441, which may be generally cylindrical in shape and thus easily formed, may extend within the bridge piston 440 and thus may provide respective, axially aligned locking pin housings or receptacles. Locking assembly 460 may include a pair of opposed locking pins 462 disposed in the respective locking pin receptacles forming the transverse bore 441.
Piston 440 may include an actuation pin receiving bore 445 for receiving actuation pin 480. Actuation pin 480 may include an outer actuation pin engagement surface 482, which may be a cylindrical portion of the actuation pin having a diameter substantially corresponding to the internal diameter of actuation pin receiving bore 445. Actuation pin 480 may also include an inner actuation pin engagement surface 484, which may be a reduced diameter cylindrical portion compared to the outer actuation pin engagement surface 482. One or more conical, chamfered or otherwise tapered transition surfaces 486 may extend between the inner actuation pin engagement surface 484 and the outer actuating pin engagement surface 482. Actuation pin 480 may cooperate with an actuation pin return spring 488, which at one end may engage an actuation pin spring seat 489 formed on the actuation pin. An opposite end of actuation pin return spring 488 may be housed within an actuation pin return spring cavity 443 defined within the bridge piston 440 and may engage an end wall 447 thereof. As will be recognized, actuator return spring 488 provides a biasing force on the actuation pin 480 tending to move the actuation pin 480 to the position shown in
Actuation pin 480 may be moved downward, against the bias of actuation pin return spring 488 under control of hydraulic fluid entering the bridge piston cap fluid passage 496 and acting upon an upper surface of the actuation pin 480. This motion transitions the collapsing bridge 400 from a locked state, shown in
As will be recognized from the instant disclosure, the use of an actuation pin 480 as shown in
According to further aspects of the disclosure, various geometries and configurations for the locking pins and actuation pin used in a collapsing valve train component may provide additional advantages, especially with regard to alignment, ease of manufacture and assembly of locking pins, actuating pin, and the collapsing valve train components generally contemplated herein. Examples of such geometries and configurations are illustrated in
The concave actuation pin engaging surfaces of the actuation pin interface of the locking pins may be configured to complementarily engage the outer actuation pin engagement surface (i.e., 482 in
Referring collectively to
Alignment surface 916 is adapted to guide and prevent rotation of the locking pin 962 during its entire travel from the extended position in engagement with the outer locking pin engagement surface 982 of actuating pin 980 to the retracted position in which locking pin is in engagement with the inner locking pin engagement surface 984 of actuating pin 480. Stated another way, when these two conical surfaces, 916 and 986, engage each other (as in the case where the actuation pin is sliding to cause locking of the bridge piston), their complementary shapes urge alignment of the locking pin with the actuation pin, thereby preventing or at least minimizing rotation of the locking pin.
Housing interface 630 of locking pin 600 may include an outer concave surface 632 and two housing engagement surfaces 634 and 636. Housing engagement surfaces 634 and 636 may engage one or respective chamfered surfaces in the annular channel in the housing bore (i.e., 419 in
Referring collectively to
A further advantage of the double conical chamfered surfaces on the actuating pin interface according to aspects of the disclosure, such as the surfaces 814 and 816 in the embodiment of
Referring additionally to
Although the present implementations have been described with reference to specific example embodiments, it will be evident that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the invention as set forth in the claims. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.
The instant application claims priority to U.S. provisional patent application Ser. No. 62/691,947 filed on Jun. 29, 2018 and titled COLLAPSING VALVE BRIDGE WITH PIN ELEMENTS, the subject matter of which is incorporated herein in its entirety.
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