US20240125254A1

US20240125254A1 - Discrete lost motion device

Info

Publication number: US20240125254A1
Application number: US18/484,045
Authority: US
Inventors: G. Michael Gron, Jr.; Bruce A. Swanbon; John MANDELL; Marc B. SILVA; Tyler HINES; Matei ALEXANDRU; Austen P. Metsack; Gabriel S. ROBERTS; P. Douglas AUBIN
Original assignee: Jacobs Vehicle Systems Inc
Current assignee: Jacobs Vehicle Systems Inc
Priority date: 2022-10-12
Filing date: 2023-10-10
Publication date: 2024-04-18
Also published as: WO2024079641A1

Abstract

A discrete lost motion device for use in a valve train of an internal combustion engine comprises a housing having a housing bore extending longitudinally into the housing and a second end having a housing contact surface configured to engage a corresponding contact surface of a first valve train component. A plunger slidably is disposed in the housing bore is controllable between a first state in which the plunger rigidly extends out of the housing bore and a second state in which the plunger is permitted to reciprocate within the housing bore, the plunger further comprising an end having a plunger contact surface configured to engage a corresponding contact surface of a second valve train component. The housing contact surface and the plunger contact surface are configured to support the discrete lost motion device between the first and second valve train components.

Description

BACKGROUND

Valve actuation in an internal combustion engine is required for the engine to operate. Typically, valve actuation forces to open the engine valves (i.e., intake, exhaust or auxiliary engine valves) are conveyed by valve trains where such valve actuation forces may be provided by main and/or auxiliary motion sources. As used herein, the descriptor “main” refers to so-called main event engine valve motions, i.e., valve motions used during positive power generation in which fuel is combusted in an engine cylinder to provide a net output of engine power, whereas the descriptor “auxiliary” refers to other engine valve motions for purposes that are alternative to positive power generation (e.g., compression release braking, bleeder braking, cylinder decompression, cylinder deactivation, brake gas recirculation (BGR), etc.) or in addition to positive power generation (e.g., internal exhaust gas recirculation (IEGR), variable valve actuations (VVA), early exhaust valve opening (EEVO), late intake valve closing (LIVC), swirl control, etc.).
In many internal combustion engines, the main and/or auxiliary motion sources may be provided by fixed profile cams, and more specifically by one or more fixed lobes or bumps which may be an integral part of each of the cams. Benefits such as increased performance, improved fuel economy, lower emissions, and better vehicle drivability may be obtained if the intake and/or exhaust valve timing and lift can be varied. The use of fixed profile cams, however, can make it difficult to adjust the timings and/or amounts of engine valve lift to optimize them for various engine operating conditions.
One method of adjusting valve timing and lift, given a fixed cam profile, has been to provide a “lost motion” or variable length device in the valve train linkage between a given engine valve and its corresponding cam. Lost motion is the term applied to a class of technical solutions for modifying the valve actuation motion defined by a cam profile with a variable length mechanical, hydraulic, or other linkage assembly. In a lost motion system, a cam lobe may provide the “maximum” (longest dwell and greatest lift) motion needed over a full range of engine operating conditions including, as required in some cases, for positive power generation operation and/or auxiliary operation. A variable length system may then be included in the valve train linkage, intermediate of the valve to be opened and the cam providing the maximum motion, to subtract or lose part or all of the motion imparted by the cam to the valve. Typically, such lost motion devices are controllable between a “locked” or motion conveying state and an “unlocked” or motion absorbing state. During the locked state, the lost motion device is maintained in a substantially rigid configuration (with allowances for lash adjustments) such that valve actuation motions applied thereto are conveyed to the corresponding engine valve(s). On the other hand, during the unlocked state, the lost motion device is permitted to absorb or avoid, i.e., “lose,” any valve actuation motions applied thereto, thereby preventing such valve actuation motions from being conveyed to the corresponding engine valve(s).
FIG. 1 schematically illustrates an embodiment of a conventional valve actuation system 100 incorporating a lost motion component 130. As shown, the valve actuation system 100 comprises a valve actuation motion source 102 that serves, in this example, as the sole source of valve actuation motions (i.e., valve opening and closing motions) to one or more engine valves 104 via a valve actuation load path 106. The one or more engine valves 104 are associated with a cylinder 105 of an internal combustion engine. As known in the art, each cylinder 105 typically has at least one valve actuation motion source 102 uniquely corresponding thereto for actuation of the corresponding engine valve(s) 104. Further, although only a single cylinder 105 is illustrated in FIG. 1 , it is appreciated that an internal combustion engine may comprise, and often does, more than one cylinder and the valve actuation systems described herein are applicable to any number of cylinders for a given internal combustion engine.
The valve actuation motion source 102 may comprise any combination of known elements capable of providing valve actuation motions, such as a cam. The valve actuation motion source 110 may be dedicated to providing exhaust motions, intake motions, auxiliary motions, a combination of exhaust or intake motions or such a combination in further combination with auxiliary motions.
As shown, the valve actuation load path 106 may comprise one or more valve train components (in the illustrated example, first and second valve train components 108, 110) deployed between the valve actuation motion source 102 and the at least one engine valve 104 and used to convey motions provided by the valve actuation motion source 102 to the at least one engine valve 104, e.g., tappets, pushrods, rocker arms, valve bridges, automatic lash adjusters, etc. Although two valve train components 108, 110 are illustrated in FIG. 1 , it is understood that a greater or lesser number of valve train components may be deployed. Further, in this example, the valve actuation load path 106 includes a lost motion component 130 housed within the second valve train component 110. That is, while the lost motion component 130 may contact other components in the valve train 106, it is fully supported within the valve train 106 by virtue of being housed within the second valve train component 110. As used herein, the term “supported” refers to being retained within, or in functional communication with, the valve train. For example, the second valve train component 110 may be embodied by a rocker arm or valve bridge having a bore formed therein in which constituent components forming the lost motion component 130 are deployed such that support for such lost motion component 130 is solely or primarily provided by the rocker arm.
As further depicted in FIG. 1 , an engine controller 120 may be provided and operatively connected to the lost motion component 130. The engine controller 120 may comprise any electronic, mechanical, hydraulic, electrohydraulic, or other type of control device for controlling operation of the lost motion mechanism 130, i.e., switching between its respective locked and unlocked states as described above. For example, the engine controller 120 may be implemented by a microprocessor and corresponding memory storing executable instructions used to implement the required control functions, including those described below, as known in the art. It is appreciated that other functionally equivalent implementations of the engine controller 130, e.g., a suitable programmed application specific integrated circuit (ASIC) or the like, may be equally employed. Further, the engine controller 120 may include peripheral devices, intermediate to engine controller 120 and the lost motion device 130, that allow the engine controller 120 to effectuate control over the operating state of the lost motion device 130. For example, where the lost motion device 130 is a hydraulically controlled mechanism (i.e., responsive to the absence or application of hydraulic fluid to an input), such peripheral devices may include suitable solenoids, as known in the art.
FIG. 2 schematically illustrates another embodiment of a conventional valve actuation system 100′ incorporating a lost motion component 230, in which like reference numerals refer to like elements as compared to FIG. 1 . In this second embodiment, the lost motion component 230, rather than being housed (and thus supported) within one of the valve train components 108, 110, is instead housed within a fixed member 232, such as a cylinder head or engine block, while still contacting the second valve train component 110. For example, in the case where the second valve train component 110 is an end pivot type rocker arm or finger follower, the lost motion component 230 may be embodied by a collapsible pivot as known in the art.
Cost, packaging and size are factors that may often determine the desirability of an engine valve actuation system. Often, where it is desirable to incorporate one or more lost motion components into valve trains, the ability to include valve train components that support such lost motion components may be constrained by a variety of factors, e.g., lack of space requirements due to their bulky size and/or greater expense. Thus, the provision of lost motions components that overcome these limitations would represent a welcome advancement of the art.

SUMMARY

The instant disclosure describes various embodiments of a discrete lost motion device for use in a valve train of an internal combustion engine, the valve train having at least a first and a second valve train component, and wherein the discrete lost motion device comprises a housing having a housing bore extending longitudinally into the housing from a first end of the housing, the housing further comprising a second end having a housing contact surface configured to engage a corresponding contact surface of the first valve train component. The discrete lost motion device further comprises a plunger slidably disposed in the housing bore through the first end of the housing and controllable between a first state in which the plunger rigidly extends out of the housing bore and a second state in which the plunger is permitted to reciprocate within the housing bore, the plunger further comprising an end having a plunger contact surface configured to engage a corresponding contact surface of the second valve train component. In the disclosed embodiments, the housing contact surface and the plunger contact surface are configured to support the discrete lost motion device between the first and second valve train components.
In an embodiment, the housing contact surface and the plunger contact surface are configured to permit rotation of the discrete lost motion device relative to the first valve train component or the second valve train components or both. For example, either of the housing contact surface and the plunger contact surface may comprise a convex contact surface or a concave contact surface or, more specifically, either of the housing contact surface and the plunger contact surface may comprise a spherical contact surface.
In an embodiment, either the second end of the housing or the end of the plunger comprises a hydraulic passage configured to receive hydraulic fluid for controlling the plunger between its first and second states. The discrete lost motion component may comprise a hydraulically controlled locking mechanism configured to, in the first state, lock the plunger relative to the housing and, in the second state, to unlock the plunger relative to the housing, wherein the hydraulic passage in is fluid communication with the hydraulically controlled locking mechanism. In one implementation, the hydraulically controlled locking mechanism defaults to a locked state and application of hydraulic fluid via the hydraulic passage causes an unlocked state of the hydraulically controlled locking mechanism whereas, in another implementation, the hydraulically controlled locking mechanism defaults to an unlocked state and application of hydraulic fluid via the hydraulic passage causes a locked state of the hydraulically controlled locking mechanism.
Furthermore, the hydraulically controlled locking mechanism may comprise an inner plunger slidably disposed in a longitudinal bore formed in the plunger and radially extending locking elements disposed in radial openings formed in the plunger, and wherein the housing bore comprises an annular recess engaged by the locking elements when the locking elements extend out of the radial openings. A longitudinal extent of the annular recess may be greater than a thickness of the locking elements up to an including the longitudinal extent of the annular recess being at least large enough to accommodate a maximum separation between the first and second valve train components when the elements extend out of the radial openings and engage the annular recess.
Alternatively, the discrete lost motion device may comprise a check valve in fluid communication with the hydraulic passage and configured to establish a volume of locked hydraulic fluid between the housing and the plunger. In this embodiment, the check valve may be deployed in a control valve upstream of the discrete lost motion device, or may be deployed within the discrete lost motion device. Furthermore, a biased pin may be arranged to open the check valve when hydraulic fluid is not being supplied via the hydraulic passage and to permit closure of the check valve when hydraulic fluid is being supplied via the hydraulic passage.
In another embodiment, the discrete lost motion device may comprise a plunger spring biasing the plunger out of the plunger bore. In this case, the plunger spring may be disposed within the housing bore or outside of the housing.
In another embodiment, travel of the plunger out of the housing bore is limited.
In yet another embodiment, either the housing contact surface or the plunger contact surface may be configured to be attached to a corresponding one of the first valve train component or the second valve train component.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages will be discussed in detail in the following non-limiting description of specific embodiments in connection with the accompanying drawings, in which:

FIGS. 1 and 2 schematically illustrate valve actuation systems in accordance with prior art techniques;

FIG. 3 schematically illustrates a valve actuation system, including a lost motion component, in accordance with the instant disclosure;

FIGS. 4-7 illustrate a first embodiment of a lost motion component in accordance with the instant disclosure;

FIGS. 8, 9 and 9A illustrate a second embodiment of a lost motion component in accordance with the instant disclosure;

FIGS. 10 and 10A illustrate a third embodiment of a lost motion component in accordance with the instant disclosure; and

FIGS. 11-16 illustrate various alternative embodiments for providing travel limiting within a lost motion component in accordance with the instant disclosure.

DETAILED DESCRIPTION OF THE PRESENT EMBODIMENTS

FIG. 3 schematically illustrates an embodiment of a valve actuation system 300 in accordance with the instant disclosure incorporating a discrete lost motion component 330, and in which like reference numerals refer to like elements as compared to FIGS. 1 and 2 . As used herein, “discrete” refers to its conventional meaning of constituting a separate entity or part. Thus, in this second embodiment, the discrete lost motion component 330, rather than being housed or supported within one of the valve train components 108, 110, as in the case of FIG. 1 , or housed or supported within a fixed member 232, as in the case of FIG. 2 , is instead formed as a discrete component that is supported within the valve train 106 by one or more of its adjoining valve train components 108, 110, as described in further detail below. Generally, support of the discrete lost motion component 330 is provided by one or more supporting joints. As used herein, a supporting joint is a meeting of two elements that are (i) joined in the sense of being in close association or relationship with each other, from being in separatable contact with each other up to and including being inseparably connected to each other, and (ii) configured to bear or hold the discrete lost motion component within a valve train. Additionally, a supporting joint may provide freedom for the discrete lost motion component 330 to rotate relative to one or more adjoining valve train components.
In the example shown in FIG. 3 , such support joints 340, 341 are schematically illustrated as comprising combinations of contact surface 330 a, 330 b deployed on the discrete lost motion component 330 and corresponding contact surfaces 108 a, 110 a deployed on the adjoining valve train components 108, 110. As described in greater detail below, the contact surfaces 330 a, 330 b of the discrete lost motion component 330 and the corresponding contact surfaces 108 a, 110 a of the valve train components 108, 110 are complementarily configured to facilitate support of the discrete lost motion component 330 by the valve train components 108, 110, as well as to facilitate operation of the discrete lost motion component 330 despite movement of the valve train components 108, 110. Thus, it is understood that the various complementary contact surfaces described herein are examples of supporting joints, or portions thereof, that may be employed to implement the discrete lost motion component 330 (and various specific embodiments thereof described below).
Thus, the valve actuation system 300 is seen to comprise the discrete lost motion component 330 and the adjacent valve train components 108, 110 that support the discrete lost motion component 330.
As further shown in FIG. 3 , control of the discrete lost motion component 330 by the engine controller 120 is provided via a path through at least one of the adjoining valve train components 108, 110. For example, in the various embodiments described hereinbelow, such control is provided through the use of hydraulic fluid supplied under the control of the engine controller 120. However, as will be appreciated by those having skill in the art, other types of control schemes may be equally employed for this purpose. In the case of fluid supplied under the control of the engine controller 120, a feature of the instant disclosure is that such fluid supply passage passes through at least one of the contact surfaces 108 a, 110 a, 330 a, 330 b, various examples of which are further illustrated and described below.
FIGS. 4-7 illustrate a first embodiment of a discrete lost motion component 400 that can be used as the discrete lost motion component 330 shown in the embodiment illustrated in FIG. 3 . In particular, FIGS. 4 and 5 illustrate opposite perspective views of the discrete lost motion component 400, which comprises a housing 402 having a plunger 410 disposed therein through a first end 404 of the housing 402. As shown, the housing 402 and plunger 410 are both centered on a longitudinal axis 420 of the discrete lost motion component 400. As described above, the discrete lost motion component 400 is configured such that its exists as a separate structure relative to other valve train components, but not encompassed by or wholly supported by a single valve train component or fixed structure, yet still in contact with other valve train components for support within the overall valve train. As best shown in FIG. 7 , the plunger 410 is slidably disposed in a housing bore 702 formed in the housing 402.
Furthermore, the housing 402 has a housing contact surface 408 formed at a second end 406 of the housing 402, and the plunger 410 has a plunger contact surface 414 formed at a first end 412 of the plunger 410 extending out the housing 402. In a particular embodiment, each of the housing and plunger contact surfaces 408, 414, such as contact surfaces 330 a, 330 b shown in FIG. 3 , is configured to mate with a complementary contact surface formed in an adjoining valve train component, such as the contact surfaces 108 a, 110 a shown in FIG. 3 . In the illustrated example, both the housing and plunger contact surfaces 408, 414 are formed as convex surfaces configured to engage corresponding and complementary concave surfaces as described below, though it is appreciated that the housing and plunger contact surfaces 408, 414 may be formed as concave surfaces configured to engage corresponding and complementary convex surface, again as described below. In yet another alternative, the housing and plunger contact surfaces 408, 414 may be formed as respective concave and convex surface, or vice versa. Regardless, in an embodiment, the convex and concave surfaces may be spherical contact surfaces. Further, as best shown in FIG. 4 , the illustrated embodiment also comprises a hydraulic passage 416 formed in the first end 412 the plunger 410 and, more particularly, with an opening of the hydraulic passage 416 formed within the plunger contact surface 414. Although the hydraulic passage 416 is illustrated as being formed within the plunger 410, it is appreciated that such a passage may alternatively be formed in the second end 406 of the housing 402 and, more particularly with an opening of the hydraulic passage 416 formed within the housing contact surface 408.
Referring now to FIG. 6 , the discrete lost motion component 400 is shown in contact with adjoining valve train components 602, 604 (shown in cross-section). In this embodiment, the convex housing and plunger contact surfaces 408, 414 are shown engaging with corresponding, concave contact surfaces 606, 608 (such as the contact surfaces 108 a, 110 a shown in FIG. 3 ) respectively formed in the adjoining valve train components 602, 604. When biasing forces are applied to (or by) the discrete lost motion component 400, resulting in contact between the discrete lost motion component 400 and the adjoining valve train components 602, 604, the mating engagement of the housing and plunger contact surfaces 408, 414 with the corresponding contact surfaces 606, 608 tends to prevent dislodgment of the discrete lost motion component 400 from between the adjoining valve train components 602, 604 due to forces applied to either the housing 402 or plunger 410 and not substantially parallel to the longitudinal axis 420 (e.g., vibrations or torques). While other configurations of the complementary contact surfaces 408, 414, 606, 608 may be employed for this purpose, as described below, the illustrated convex and concave surfaces permit rotational movement of the adjoining valve train components 602, 604 relative to either the housing 402 or plunger 410 the extent that the contact surfaces 408, 414, 606, 608 are permitted to slide relative to one another without losing the mating engagement.
As further shown in FIG. 6 , a first valve train component 602 is configured with a first hydraulic passage 610 that registers with the hydraulic passage 416 formed in the plunger 410. In an embodiment, the respective diameters of the hydraulic passages 416, 610 are sufficiently large to ensure fluid communication between the hydraulic passages 416, 610 despite rotational movement of the first valve train component 602 relative to the plunger 410. As described with reference to FIG. 7 , the supply or removal of pressurized hydraulic fluid (e.g., from an engine oil pump) through the hydraulic passages 416, 610 may provide control of locked and unlocked states of operation of the discrete lost motion component 400.
Referring now to FIG. 7 , the discrete lost motion component 400 is depicted in cross section, thereby better illustrating a hydraulically controlled locking mechanism 704 deployed between the housing 402 and plunger 410. A plunger spring 716 is provided to bias the plunger 410 out of the housing 402. The locking mechanism 704 shown in FIG. 7 is generally of the type described in U.S. Pat. No. 9,790,824, the teachings of which patent are incorporated herein by this reference and replicated in relevant part below.
As shown in FIG. 7 , the locking mechanism 704 includes the plunger 410 disposed within a housing bore 702 formed in and extending along the longitudinal axis 420 from the first end 404 of the housing 402. An inner plunger 710 is slidably disposed in a longitudinal bore 714 formed in the plunger 410. Locking elements in the form of wedges 706 are provided, which wedges are configured to engage with an annular outer recess 708 formed in a surface defining the housing bore 702. The illustrated embodiment is of a normally locked locking mechanism 704, i.e., in the absence of hydraulic control applied to the inner plunger 710 via, in this case, the hydraulic passage 416, an inner plunger spring 712 biases the inner plunger 710 into position such that the wedges 706 contact a full-diameter portion of the inner plunger 710 and therefore radially extend out of openings formed in the plunger 410, thereby engaging the outer recess 708 and effectively locking the plunger 410 in place relative to the housing 402.
In this locked state, any valve actuation motions (whether main or auxiliary motions, subject to lash provisions provided by the discrete lost motion component) applied to either end of the discrete lost motion component 400 are conveyed thereby. It is noted that, despite being in the locked state as shown in FIG. 7 , a longitudinal extent of the outer recess 708 is greater than a thickness of the wedges 706 such that a small amount of movement is nevertheless permitted between the plunger 410 and housing 403 as described in further detail below. As shown in FIG. 7 , this additional space has been taken up as in the case, for example, where a valve actuation motion has been applied to the discrete lost motion component 400 thereby overcoming any outward bias applied by the plunger spring 716 to the plunger 410.
Alternatively, when the discrete lost motion component 400 is unloaded (e.g., during cam base circle) while still in the locked state, the bias applied by the plunger spring 716 causes the plunger 410 to translate in its bore 702 to the extent permitted by the longitudinal extent of the outer recess 708, i.e., to the left as shown in FIG. 7 until the wedges 706 abut the leftmost surface of the outer recess 708. In this manner, the plunger spring 716 ensures that the housing and plunger contact surfaces 408, 414 continue to be biased into contact with the corresponding contact surfaces 608, 606 (as shown in FIG. 6 ) of the adjoining valve train components 602, 604, provided that such longitudinal extent is larger than any lash within the valve train when in the unloaded state.
Such bias applied by the plunger spring 716 can be selected to additionally ensure that the adjoining valve train components 602, 604 (or such additional up- or downstream valve train components in the system, not shown) are biased into continuous contact with respective endpoints of the valve train, i.e., valve actuation motions sources and engine valves. Further still, because outward travel of the plunger 410 from within its bore 702 is limited by the longitudinal extent of the outer recess 708 (when in the locked state), the bias applied by the plunger spring 716 to the adjacent valve train components 602, 604 (and, once again, any additional up- or downstream valve train components in the system) will not apply excess biasing forces against the normal operation of any automatically adjustable, compliant components within the valve train, e.g., hydraulic lash adjusters or the like. As described relative to further embodiments below, other implementations providing such travel limiting of the plunger 410 relative to the housing 402, even during an unlocked state of the discrete lost motion component 400, may also be employed for this purpose.
Referring again to FIG. 7 , provision of hydraulic fluid to the top of the inner plunger 710 (leftmost surface as shown in FIG. 7 ) via the hydraulic passage 416, sufficiently pressurized to overcome the bias of the inner plunger spring 712, causes the inner plunger 710 to translate within the bore 714 such that the wedges 706 are aligned with a reduced-diameter portion of the inner plunger 710 and are permitted to retract and disengage from the outer recess 708, thereby effectively unlocking the plunger 410 relative to the housing 402 and permitting the plunger 410 to slide freely within its bore 702, subject, in this case, to the bias provided by the plunger spring 716. In this unlocked state, any valve actuation motions applied to the discrete lost motion component 400 will cause the plunger 410 to reciprocate in its bore 702. In this manner, and presuming travel of the plunger 410 into its bore 702 is greater than the maximum extent of any applied valve actuation motions (i.e., that the plunger 410 is unable to bottom out in its bore 702), such valve actuation motions are not conveyed by the discrete lost motion component 400 and are effectively lost.
FIGS. 8, 9 and 9A illustrate a second embodiment of a discrete lost motion component 800 that can be used as the discrete lost motion component 330 shown in the embodiment illustrated in FIG. 3 . As shown, this embodiment similarly includes a housing 802 and plunger 911 disposed along a longitudinal axis 820. In this case, however, the function of the plunger spring 716 depicted in FIG. 7 is implemented by a plunger spring 830 deployed on the outside of the housing 802 and plunger 911. As best shown in FIG. 9 , the plunger spring 830 is deployed between a flange 930 formed on or attached to an outer surface of the plunger 911 and a shoulder 932 formed in the housing 802 as shown. In the illustrated embodiment, the flange 930 is secured to the plunger 911 via an annular notch 931 formed in an outer surface of the plunger 911. As further shown in FIG. 9 , the discrete lost motion component 800 again includes a locking mechanism 904 comprising an inner plunger 910, wedges 906 and annular channel 908 that operates in the same manner, under the control of hydraulic fluid supplied by a hydraulic passage 916 formed in the plunger 911, as the corresponding components described above relative to FIG. 7 . Further still, in this embodiment, the housing 802 is not formed as a unitary component, but instead has an end cap 940 securely attached to the housing 802, which is implemented in this embodiment substantially as tube or cylinder having its second end closed off by the end cap 940. In this embodiment, the housing contact surface 808 is formed in the end cap 940.
FIG. 9 also illustrates adjoining valve train components 920, 924 having respective contact surfaces 922, 926 configured to engage with corresponding housing and plunger contact surfaces 808, 814. In this case, however, while the housing contact surface 808 is formed as a convex surface (in keeping with the embodiment of FIGS. 4-7 ) configured to mate with a corresponding concave contact surface 922 of the adjoining valve train component 920, the plunger contact surface 814 is formed as a concave surface configured to mate with a corresponding convex surface 926 of the adjoining valve train component 924. By oppositely configuring the housing and plunger contact surfaces 808, 814 in this manner, the opportunity for incorrectly installing the discrete lost motion component 800, i.e., upside down relative to the orientation shown in FIG. 9 , can be effectively avoided.
FIG. 9A illustrates an example of a discrete lost motion component 800′ similar to the embodiment depicted in FIG. 9 , but that instead operates as normally unlocked. Elements having like reference numerals in FIGS. 9 and 9A are substantially similar in structure and function, whereas reference numerals including a prime symbol (′) in FIG. 9A refer to elements that are characterized by differing structure and/or function relative to counterparts illustrated in FIG. 9 , as described below. In the embodiment illustrated in FIG. 9A, the lost motion component 800′ once again includes a housing 802′ having a longitudinal bore formed therein, and a plunger 911′ slidably disposed in the bore. Likewise, an inner plunger 910′ is disposed in a bore formed in the plunger 911′ and biased out of the bore by an inner plunger spring disposed between the inner plunger 910′ and a plunger cap 950 threadedly (in this case) secured to the plunger 911′.
However, in this case, the inner plunger 910′ is structured essentially opposite the inner plunger 910 shown in FIG. 9 such that, in the absence of hydraulic control applied to the inner plunger 910′, the inner plunger spring biases the inner plunger 910′ into position such that the wedges 906 do not radially extend out of openings formed in the plunger 911′ and therefore do not engage the outer annular recess 908′, thereby effectively unlocking the plunger 911′ relative to the housing 802′ and permitting the plunger 911′ to slide freely within its bore, subject to the bias provided by the plunger spring 930. In this unlocked state, any valve actuation motions applied to the lost motion component 800′ will cause the plunger 911′ to reciprocate in its bore. In the illustrated embodiment, the plunger 911′ is configured such that travel of the plunger 911′ within its bore permits the plunger 911′ to “bottom out,” i.e., to make contact, in this case, between the plunger cap 950 and the closed end of the bore. In this manner, the lost motion component 800′ is able to prevent overextension of any hydraulic lash adjuster disposed in the same valve train as the lost motion component 800′. Additionally, such travel limiting of the plunger 911′ permits application of a “failsafe” auxiliary valve actuation motion, e.g., a high-lift braking gas recirculation (BGR) motion, in the event of failure of the locking mechanism.
On the other hand, provision of hydraulic fluid to the input-receiving end (bottommost surface as shown in FIG. 9A) of the inner plunger 910′ sufficiently pressurized to overcome the bias of the inner piston spring, causes the inner plunger 910′ to translate within the bore such that the wedges 906 are forced to radially extend out of the opening formed in the plunger 911′ and engage with the outer recess 908′, thereby effectively locking the plunger 911′ relative to the housing 802′. In this locked state, valve actuation motions applied to the lost motion component 800′ will cause the plunger 911′ to engage the housing 802′ thereby transmitting such valve actuation motions.
A further feature of the housing 802′ depicted in FIG. 9A is that the annular outer recess 908′ has a longitudinal extent such that the plunger 911′ is permitted to slide within its bore even when the lost motion component 800′ is in its locked/motion conveying state. This configuration of the outer recess 908′ accommodates separation between the valve train components adjacent to the discrete lost motion component 800′ that might otherwise permit the discrete lost motion component 800′ to lose contact with either or both of its adjacent valve train components, thereby potentially coming dislodged from the valve train. For example, it is anticipated that, in some valve actuation systems, a valve train component on an output side of the discrete lost motion component 800′ could be caused to translate away from the discrete lost motion component 800′ (and the valve train component on an input side of the discrete lost motion component 800′) due to valve actuation motions arising outside of the valve train in which the discrete lost motion component 800′ resides. In this case, the ability of the discrete lost motion component 800′ to expand up to the maximum possible separation between the adjacent valve train components without losing contact with the adjacent valve train components permits the relevant contact surfaces (e.g., 108 a, 110, 330 a, 330 b) to continue to support the discrete lost motion component 800′ within the valve train.
FIG. 10 illustrates a third embodiment of a discrete lost motion component 1000 that can be used as the discrete lost motion component 330 shown in the embodiment illustrated in FIG. 3 . Unlike the embodiments shown in FIGS. 4-9 and 9A, in which a mechanically-based locking mechanism 704, 904 is provided to effectuate the locked/unlocked states of the lost motion mechanism 400, 800, the lost motion mechanism 1000 is entirely hydraulic in its implementation. In particular, the discrete lost motion component 1000 again comprises a housing 1002 and a plunger 1004 disposed in a longitudinally extending bore 1005 formed in the housing 1002. A spring 1006 is provided, in this implementation, to bias the plunger 1004 out of the bore 1005 and into continuous contact with the adjoining valve train component (not shown). However, it is appreciated that the spring 1006 could also be configured to ensure biasing of the plunger 1004 into the bore 1005. Furthermore, though illustrated as being disposed within the housing 1002, the spring 1006 could be equally deployed on the outside of the housing 1002.
Regardless, a hydraulic passage 1008 is provided in the housing 1008, thereby providing fluid communication between the bore 1005 and a hydraulic supply source 1012 via an intermediate control valve 1010 of the type known in the art. When hydraulic fluid is provided to the control valve 1010, hydraulic fluid is permitted to flow into the bore 1005 until such time as pressure equalizes on either side of a check valve (not shown) disposed in the control valve 1010. At that time, the control valve 1010 checks the fluid disposed in the bore 1005 thereby establishing a locked volume of fluid within the bore 1005 such that the plunger 1004 is rigidly maintained in its extended position out of the bore 1005, i.e., the lost motion mechanism 1000 is in a locked state. Conversely, when fluidic pressure from the fluid source 1012 to the control valve is removed, the control valve 1010 operates to permit the locked volume of fluid to vent from the bore 1005, which in turn allows the plunger 1004 to reciprocate in the bore 1005, i.e., the lost motion mechanism 1000 is in an unlocked state.
An alternative implementation of the third embodiment is illustrated in FIG. 10A in which a control valve 1010′ is disposed within a housing 1002′ of a discrete lost motion component 1000′, as opposed to externally as depicted in FIG. 10 . Once again, elements having like reference numerals in FIGS. 10 and 10A are substantially similar in structure and function, whereas reference numerals including a prime symbol (′) in FIG. 10A refer to elements that are characterized by differing structure and/or function relative to counterparts illustrated in FIG. 10 , as described below.
In this implementation, the discrete lost motion component 1000′ comprising a housing 1002′ having a plunger bore 1005′ in which a plunger 1004′ is slidably disposed. Though not illustrated in FIG. 10A, the plunger 1004′ may be suitably biased into or out of the plunger bore 1002′ using a suitable spring (not shown). The housing 1002′ further comprises a piston bore 1022 formed opposite the plunger bore 1005′ and in fluid communication with the plunger bore 1005′ via a connecting passage 1040. A piston 1020 is slidably disposed in the piston bore 1022 and biased toward the connecting passage 1040 and plunger bore 1005′ by a piston spring 1030. Note that contact surfaces 1050, 1052, substantially similar to those discussed above, are respectively provided on an input cap 1014 and the plunger 1004′ (in this case, as respective concave and convex surfaces).
A control valve assembly 1010′ comprises a check ball 1024 and a check ball guide 1026 securely disposed between the connecting passage 1040 and the plunger bore 1005′. A check ball spring 1028 is disposed between the check ball guide 1026 and the check ball 1024 to bias the check ball 1024 into a seat formed at an end of the connecting passage 1040, thereby tending to close off fluid communication between the connecting passage 1040 and the plunger bore 1005′. However, the piston 1020 further comprises a pin 1032 extending away from a body portion of the piston, through the connecting passage 1040 and toward the check ball 1024. Under the bias of the piston spring 1030, which is stronger than the bias applied by the check ball spring 1028 applied to the check ball 1024, and absent application of any hydraulic fluid to the discrete lost motion component 1000′ (as described below), the pin 1032 will unseat the check ball 1024 from its seat at the end of the connecting passage 1040, thereby preserving fluid communication between the connecting passage 1040 and the plunger bore 1005′.
As further shown in FIG. 10A, the discrete lost motion component 1000′ further comprises an input cap 1014 securely disposed at an open end of the piston bore 1022. The input cap 1014 comprises the hydraulic passage 1008′ through which hydraulic fluid from the hydraulic fluid source 1012 may be received. In turn, the hydraulic passage 1008′ is in fluid communication with radially-extending channels 1042 also formed in the input cap 1014.
The housing 1002′ further comprises first, second and third hydraulic passages 1034, 1036, 1038. The first hydraulic passage 1034, which may be fabricated as one or more radial channels or an annular notch, is configured to align with at least one of the radially-extending channels 1042 such that fluid communication is provided therebetween. In turn, the second hydraulic passage 1036 is in fluid communication with the first hydraulic passage 1034. In the illustrated example, the second hydraulic passage 1036 is formed as two more vertically or longitudinally extending channels that intersect, and thereby establish fluid communication with, the third hydraulic passage 1038. As shown, the third hydraulic passage 1038 may comprise a transversely formed passage or additional annular notch. Regardless, the third hydraulic passage 1038 establishes fluid communication with the piston bore 1022 such that hydraulic fluid supplied through the third hydraulic passage 1038 will establish hydraulic fluid pressure that opposes the bias of the piston spring 1030.
As noted above, the absence of hydraulic fluid applied through the hydraulic passage 1008′ and, therefore, the first, second and third hydraulic passages 1034-1038, will result in continuing unseating of the check ball 1024, as shown in FIG. 10A, such that any hydraulic fluid within the plunger bore 1005′ is permitted to escape through the connecting passage 1040 and ultimately back through the hydraulic passage 1008′. This, in turn, permits the plunger 1004′ to reciprocate in its bore 1005′, thereby losing any valve actuation motions applied to the discrete lost motion component 1000′.
On the other hand, provision of hydraulic fluid through the hydraulic passage 1008′ will cause hydraulic fluid to flow through the first, second and third passages 1034-1038 and the connecting passage 1040, and ultimately into the plunger bore 1005′, thereby extending the plunger 1004′ (when unloaded by any valve actuation motions) out of the plunger bore 1005′. During this time, the check ball 1024 will remain unseated until such time that hydraulic pressure within the plunger bore 1005′ exceeds the combined hydraulic pressure of the hydraulic fluid flowing through the connecting passage 1040 and the bias provided by the piston spring 1030, thereby causing the check ball 1024 to seat against the opening of between the plunger bore 1005′ and the connecting passage 1040. In this manner, a locked volume of hydraulic fluid will be established in the plunger bore 1005′ such that plunger 1004′ is maintained in its extended position, whereby valve actuation motions applied to the discrete lost motion component 1000′ are not lost, but are instead conveyed.
As noted above, it is desirable to incorporate some form of stroke limiting to prevent overextension of the plunger out of its bore in the housing. In addition to preventing excessive bias forces being applied to valve train components in a valve train (particularly hydraulic lash adjusters, which would then be unable to operate as usual), such travel limiting may be of particular benefit during system manufacturing and/or discrete lost motion component deployment where such outward bias force may make installation difficult or cause the discrete lost motion component to disassemble itself prior to installation. FIGS. 11-16 illustrate various embodiments for implementing such travel limiting features.
FIG. 11 illustrates a discrete lost motion component 1100 that can be used as the discrete lost motion component 330 shown in the embodiment illustrated in FIG. 3 . The illustrated discrete lost motion component 1100 is similar to those described above in that a housing 1102 has a plunger 1110 disposed therein. In this case, however, an adjustable portion 1140 of an adjacent valve train component 1150 includes a threaded portion 1142 engaging a complementarily threaded portion of the valve train component 1150. During installation of the discrete lost motion component 1100, the adjustable portion 1140 is adjusted to provide a maximum opening or distance between the adjacent valve train components 1150, 1152 such that discrete lost motion component 1100 may be installed without having to compress the housing 1102 and plunger 1110 together in order to fit the available gap. Once discrete lost motion component 1100 is properly positioned between the adjacent valve train components 1150, 1152, the adjustable portion 1140 is turned in the same manner as a conventional lash screw to decrease the gap between the adjacent valve train components 1150, 1152. In particular, it is desirable to set the adjustable portion 1140 such that a preload is applied to the plunger spring 1116 such that the wedges 1106 (when placed in the locked position such that they engage the outer recess 1108) are positioned at a desired position along the longitudinal length of the outer recess 1108.
FIG. 12 illustrates a discrete lost motion component 1200 that can be used as the discrete lost motion component 330 shown in the embodiment illustrated in FIG. 3 . In this embodiment, the housing 1202 and plunger 1210 of the discrete lost motion component 1200 are modified to accommodate the deployment of an expansion or C ring 1230 therebetween. In particular, the housing as an annular recess 1232 formed on the inner surface of the housing bore receiving the plunger 1210; in effect, the annular recess 1232 is a larger-diameter portion of the housing bore. On the other hand, the plunger 1210 has, at a second end thereof disposed within the housing bore, a channel 1234 formed on an outer surface thereof and configured to receive the expansion ring 1230. During assembly of the discrete lost motion component 1200, the expansion ring 1230 is disposed on the channel 1234 and compressed such that the expansion ring 1230 and plunger 1210 may be inserted in the housing bore. Once the expansion ring 1230 is aligned with the annular recess 1232, the expansion ring 1230 expands to extend out the channel 1234 without becoming fully disengaged therefrom. The thickness of the expansion ring 1230 and the depth of the annular recess 1230 are configured such that the expansion ring 1230 can travel along the longitudinal length of the annular recess 1232 while simultaneously engaged with the channel 1234. In this manner, as the plunger 1210 travels out of the housing bore (under bias applied by the plunger spring), the expansion ring 1230 will eventually abut the lower limit of the annular recess 1232 (as shown in FIG. 12 ). When this occurs, and because the expansion ring 1230 remains engaged with the channel 1234, the plunger 1210 will be prevented from further travel out of the housing bore.
FIGS. 13 and 14 illustrate a discrete lost motion component 1300 that can be used as the discrete lost motion component 330 shown in the embodiment illustrated in FIG. 3 . In this embodiment, the discrete lost motion component 1300 includes a pin 1330 to prevent over-travel of the plunger 1310 relative to the housing 1302. In particular, FIG. 13 illustrates a view in which the pin 1330 is parallel to the plane of the illustration whereas FIG. 14 illustrates a view in which the pin 1330 is perpendicular to the plane of the illustration, i.e., rotated by 90 degrees relative to the plane of illustration depicted in FIG. 13 . In this embodiment, and as best shown in FIG. 13 , the pin 1330 is rigidly mounted transverse to (i.e., along a diameter of) the plunger 1310. Simultaneously, and as best shown in FIG. 14 , ends of the pin 1330 are aligned with and disposed in an external slot 1402 formed in the housing 1402. In this embodiment, a lower boundary of the slot 1402 is configured to engage with the pin 1330 when the plunger 1310 is biased out of the housing bore. Because the pin 1330 is rigidly mounted to the plunger 1310, this engagement between the pin 1330 and lower boundary of the slot 1402 will prevent further travel of the plunger 1310 out of the housing bore.
In an alternative implementation of the embodiment illustrated in FIGS. 13 and 14 , in which travel limiting is only desired during a manufacturing or assembly phase, the pin 1330 may be configured to be removably mounted in a transverse channel formed in the second end of the plunger 1310. Further to this alternative implementation, the slot 1402 may be replaced with a hole having a substantially similar diameter to the pin 1330. In this case, during assembly of the discrete lost motion component 1300, the housing 1302 and plunger 1310 may be compressed until such time that the transverse channel of the plunger 1310 aligns with the hole formed in the housing 1302 such that the pin 1330 can be inserted through the hole and into the transverse channel, thereby effective locking the plunger 1310 to the housing 1302. In this embodiment, the longitudinal locations of the transverse channel in the plunger 1310 and the hole in the housing 1302 are selected such that, when the pin 1330 is inserted in the hole and transverse channel, the overall longitudinal length of the discrete lost motion component 1300 is sufficiently small to ensure ease of installation of the discrete lost motion component 1300 in a valve train. Once the discrete lost motion component 1300 is properly positioned in the valve train, the pin 1300 (which may have a suitable grasping element, like a ring in a “grenade pin”) may be removed, thereby allowing the plunger 1310 to expand out the housing bore (once again, under the bias of a plunger spring) until further travel is impeded by contact of the respective housing 1302 and plunger 1310 with the adjacent valve train components (not shown), thereby completing the installation.
FIG. 15 illustrates a discrete lost motion component 1500 that can be used as the discrete lost motion component 330 shown in the embodiment illustrated in FIG. 3 . In this embodiment, the discrete lost motion component 1500 once again comprises a housing 1502 and plunger 1510 biased apart from each other by a plunger spring 1516. However, as further shown, a sheath or outer shell 1560 (only partially shown) is provided having lower flange 1564 extending radially inward and configured to be trapped between the plunger spring 1516 and a flange portion 1530 of the plunger 1510. At its upper end, the outer shell 1560 comprises, in this embodiment, a plurality of tabs or fingers 1562 also extending radially inward and configured to engage with an upper surface of an end cap 1540 of the housing 1502. In contrast with the lower flange 1564, which is trapped between the plunger spring 1516 and plunger flange 1530, the fingers 1562 are not attached to the end cap 1540 and are instead free to separate from the end cap 1540 if the plunger 1510 is permitted to reciprocate in the housing bore. That is, when the plunger 1510 is in an unlocked state relative to the housing 1502, the plunger 1510 may retreat into the housing bore, i.e., translate upward as shown in FIG. 15 . Because the outer shell 1560 is effectively attached to the plunger 1510, it too will translate upward since the fingers 1562 are not attached to the end cap 1540. However, when the plunger 1510 extends out of the housing bore, under the influence of the plunger spring 1516, the outer shell 1560 will likewise translate downward as shown in FIG. 15 until such point that the fingers 1562 engage the upper surface of the end cap 1540. At this point, further expansion of the plunger spring 1516 is prevented by the lower flange 1564 of the outer shell 1560, thereby limiting further travel of the plunger 1510.
FIG. 16 illustrates a discrete lost motion component 1600 that can be used as the discrete lost motion component 330 shown in the embodiment illustrated in FIG. 3 . Once again, the discrete lost motion component 1600 comprises a housing 1602 and plunger 1610. However, the illustrated discrete lost motion component 1600 differs from previously described embodiments in that the illustrated locking mechanism 1604 is configured to be in a normally unlocked state, and a plunger spring 1616 is configured to bias the plunger 1610 into the housing bore formed in the housing 1602. In this case, the locking mechanism 1604 has an inner plunger 1611 biased by an inner plunger spring 1612 (and unresisted by any hydraulic force) such that the wedges 1686 are permitted to retract and disengage from the outer recess 1608, thereby unlocking the plunger 1610 from the housing 1602. On the other hand, when hydraulic pressure is applied to inner plunger 1611 (via a hydraulic passage 1680), the wedges 1686 are caused to extend outward and engage the outer recess 1608, thereby locking the plunger 1610 to the housing 1602.
Additionally, given the configuration of the plunger spring 1616, the plunger 1610 is prevented from over-extending out the housing bore. It is appreciated that this inward biasing of the plunger 1610 will prevent the plunger spring 1616 from urging contact between the contact surfaces of the plunger 1610 and housing 1602 and their respective adjacent valve train components. Consequently, in this embodiment, it is anticipated that one or more of the adjacent valve train components (or another up- or downstream valve train component) will need a biasing force to be applied thereto such that one or both of the adjacent valve train components is biased into contact with the discrete lost motion component 1600.
While the various embodiments in accordance with the instant disclosure have been described in conjunction with specific implementations thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. For instance, features of individual embodiments described herein may be employed, where practicable, within any of the other embodiments described herein. As a specific example, while the longitudinally extended annular channel 908′ of FIG. 9A is described in connection with a normally unlocked embodiment, it is appreciated that the extended annular channel 908′ could be equally employed with any of the normally locked embodiments described herein.
Accordingly, the preferred embodiments of the invention as set forth herein are intended to be illustrative only and not limiting so long as the variations thereof come within the scope of the appended claims and their equivalents.

Claims

What is claimed is:

1. A discrete lost motion device for use in a valve train of an internal combustion engine, the valve train having at least a first and a second valve train component, the lost motion device comprising:

a housing having a housing bore extending longitudinally into the housing from a first end of the housing, the housing further comprising a second end having a housing contact surface configured to engage a corresponding contact surface of the first valve train component; and

a plunger slidably disposed in the housing bore through the first end of the housing and controllable between a first state in which the plunger rigidly extends out of the housing bore and a second state in which the plunger is permitted to reciprocate within the housing bore, the plunger further comprising an end having a plunger contact surface configured to engage a corresponding contact surface of the second valve train component,

wherein the housing contact surface and the plunger contact surface are configured to support the discrete lost motion device between the first and second valve train components.

2. The discrete lost motion device of claim 1, wherein the housing contact surface and the plunger contact surface are configured to permit rotation of the discrete lost motion device relative to the first valve train component or the second valve train components or both.

3. The discrete lost motion device of claim 2, wherein either of the housing contact surface and the plunger contact surface may comprise a convex contact surface or a concave contact surface.

4. The discrete lost motion device of claim 3, wherein either of the housing contact surface and the plunger contact surface may comprise a spherical contact surface.

5. The discrete lost motion device of claim 1, wherein either the second end of the housing or the end of the plunger comprises a hydraulic passage configured to receive hydraulic fluid for controlling the plunger between its first and second states.

6. The discrete lost motion device of claim 5, further comprising:

a hydraulically controlled locking mechanism configured to, in the first state, lock the plunger relative to the housing and, in the second state, to unlock the plunger relative to the housing,

wherein the hydraulic passage in is fluid communication with the hydraulically controlled locking mechanism.

7. The discrete lost motion device of claim 6, wherein the hydraulically controlled locking mechanism defaults to a locked state and application of hydraulic fluid via the hydraulic passage causes an unlocked state of the hydraulically controlled locking mechanism.

8. The discrete lost motion device of claim 6, wherein the hydraulically controlled locking mechanism defaults to an unlocked state and application of hydraulic fluid via the hydraulic passage causes a locked state of the hydraulically controlled locking mechanism.

9. The discrete lost motion device of claim 6, wherein the hydraulically controlled locking mechanism comprises an inner plunger slidably disposed in a longitudinal bore formed in the plunger and radially extending locking elements disposed in radial openings formed in the plunger, and wherein the housing bore comprises an annular recess engaged by the locking elements when the locking elements extend out of the radial openings.

10. The discrete lost motion device of claim 9, wherein a longitudinal extent of the annular recess is greater than a thickness of the locking elements.

11. The discrete lost motion device of claim 9, wherein a longitudinal extent of the annular recess is at least large enough to accommodate a maximum separation between the first and second valve train components when the elements extend out of the radial openings and engage the annular recess.

12. The discrete lost motion device of claim 5, further comprising:

a check valve in fluid communication with the hydraulic passage and configured to establish a volume of locked hydraulic fluid between the housing and the plunger.

13. The discrete lost motion device of claim 12, wherein the check valve is deployed in a control valve upstream of the discrete lost motion device.

14. The discrete lost motion device of claim 12, wherein the check valve is deployed within the discrete lost motion device.

15. The discrete lost motion device of claim 14, further comprising:

a biased pin arranged to open the check valve when hydraulic fluid is not being supplied via the hydraulic passage and to permit closure of the check valve when hydraulic fluid is being supplied via the hydraulic passage.

16. The discrete lost motion device of claim 1, further comprising:

a plunger spring biasing the plunger out of the plunger bore.

17. The discrete lost motion device of claim 16, wherein the plunger spring is disposed within the housing bore.

18. The discrete lost motion device of claim 16, wherein the plunger spring is disposed outside of the housing.

19. The discrete lost motion device of claim 1, wherein travel of the plunger out of the housing bore is limited.

20. The discrete lost motion device of claim 1, wherein either the housing contact surface or the plunger contact surface is configured to be attached to a corresponding one of the first valve train component or the second valve train component.