Patent Publication Number: US-11028737-B2

Title: Mechanical retention member for valvetrain components

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a national stage application of International (PCT) Patent Application Serial No. PCT/US2017/062947, Nov. 22, 2017, the complete disclosure of which is expressly incorporated by reference herein. 
     FIELD OF THE INVENTION 
     The present invention relates generally to retaining a position of various valvetrain components and, more particularly, to mechanically retaining valvetrain components positioned within a cylinder head of an engine. 
     BACKGROUND OF THE DISCLOSURE 
     A valvetrain assembly for an engine may include a small clearance between a valve and a rocker arm or cam follower. This small clearance therebetween allows for thermal expansion of one or more of the parts without causing the components to interfere with each other during operation of the engine. However, this small clearance also may cause some noise and wear as the parts contact each when the engine is operating. 
     To allow for operation of the valvetrain components while minimizing noise and wear due to the small clearance provided between a valve and its associated rocker arm or cam follower, a hydraulic lash adjuster may be used. More particularly, the hydraulic last adjuster may be provided to compensate for the small clearance between such components, thereby allowing the valvetrain assembly to operate with minimal or zero clearance between the valve and its associated rocker arm or cam follower. However, if the hydraulic lash adjuster fails or operates incorrectly (e.g., excessive lash caused by loss of hydraulic fluid or a slow-to-respond lash adjuster in cold temperatures), the cross-head of the valvetrain assembly may fall off of the tips of the valves, thereby causing misfire and/or damage to the engine. 
     However, if the valvetrain assembly includes a mechanism to retain the position of the cross-head during a failure or incorrect operation of the lash adjuster, additional mass or weight is undesirably added to the valvetrain assembly which may affect the operating speed of the engine. Alternatively, software may be used to electronically or otherwise control the position of the cross-head during a failure of the lash adjuster, but this increases the complexity of the overall engine system and may introduce an additional failure mechanism to the engine if the software and/or electronics were to operate incorrectly. 
     As such, there is a need for a separate mechanism configured to retain the cross-head on the tips of the valves even during a failure or incorrect operation of the lash adjuster. Additionally, such a mechanism should not interfere with normal or routine operation of the engine and allow for the necessary movement of the cross-head for operating the valves. 
     SUMMARY OF THE DISCLOSURE 
     In one embodiment, a retention member is configured to be supported within a cylinder head of an engine and comprises a body portion and a plurality of arms. The body portion has an opening configured to receive a fuel injector of the engine. Additionally, the plurality of arms extends from the body portion and is configured to be positioned over a portion of a cross-head of the engine. The plurality of arms is spaced apart from the cross-head during routine operation of the engine. 
     In another embodiment, a retention member is configured to be operably coupled a valvetrain assembly of an engine and comprises a body portion positioned intermediate a first valve and a second valve of the valvetrain assembly. The retention also comprises a first plurality of arms configured to be positioned relative to the first valve and a second plurality of arms configured to be positioned relative to the second valve. The body portion, first plurality of arms, and second plurality of arms are stationary relative to movement of the first and second valves. 
     In a further embodiment, an engine comprises a cylinder having a body portion and a cylinder head configured to be coupled with the body portion. The engine also comprises a valvetrain assembly supported on at least a portion of the cylinder and including an intake valve, an exhaust valve, a first cross-head operably coupled to the intake valve, and a second cross-head operably coupled to the exhaust valve. The engine also comprises a retention member configured to maintain a position of the cross-heads relative to the intake and exhaust valves. The retention member is removable relative to the cross-heads. 
     Additional features and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrative embodiment exemplifying the best mode of carrying out the invention as presently perceived. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and many of the intended advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description when taken in conjunction with the accompanying drawings. 
         FIG. 1A  is a perspective view of a cylinder of an engine including a portion of a valvetrain assembly positioned within a cylinder head portion of the cylinder; 
         FIG. 1B  is another perspective view of the cylinder and valvetrain assembly of  FIG. 1A ; 
         FIG. 2  is a top view of the cylinder of  FIG. 1A ; 
         FIG. 3  is an exploded view of the portion of the valvetrain assembly of  FIG. 1A , including a mechanical retention member; 
         FIG. 4  is a cross-sectional view of the cylinder of  FIG. 2 , taken along line  4 - 4  of  FIG. 2 ; 
         FIG. 5  is a cross-sectional view of the cylinder of  FIG. 2 , taken along line  5 - 5  of  FIG. 2 ; and 
         FIG. 6  is a perspective view of the mechanical retention member of  FIG. 3 . 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of various features and components according to the present disclosure, the drawings are not necessarily to scale and certain features may be exaggerated in order to better illustrate and explain the present disclosure. The exemplifications set out herein illustrate embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION OF THE DRAWINGS 
     For the purposes of promoting an understanding of the principals of the invention, reference will now be made to the embodiments illustrated in the drawings, which are described below. The embodiments disclosed below are not intended to be exhaustive or limit the invention to the precise form disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may utilize their teachings. It will be understood that no limitation of the scope of the invention is thereby intended. The invention includes any alterations and further modifications in the illustrative devices and described methods and further applications of the principles of the invention which would normally occur to one skilled in the art to which the invention relates. 
     Referring to  FIGS. 1A-5 , a portion of an internal combustion engine  10  is shown. Engine  10  includes at least one cylinder  12  having a cylinder body portion  14  and a cylinder head portion  16 . Cylinder  12  supports a fuel injector  18  and a portion of a valvetrain assembly  20 . Fuel injector  18  is configured to be supported on cylinder  12  and, more particularly, on cylinder head portion  16 , with a clamp  19 , as shown best in  FIG. 3 . Valvetrain assembly  20  is configured to operate with rotation of a crankshaft (not shown) of engine  10  to facilitate combustion within a combustion chamber of cylinder  12 . 
     Illustratively, and as shown in  FIGS. 1A-5 , valvetrain assembly  20  includes an intake valve  22  and an exhaust valve  24 . Intake valve  22  is operably coupled to an intake rocker arm  26  which is configured to pivot or otherwise move in response to reciprocating motion of an intake pushrod  28 . More particularly, an intake cross-head  30  is positioned longitudinally intermediate (e.g., generally vertically between) a tip  32  of intake valve  22  and intake rocker arm  26 . In this way, as intake pushrod  28  moves in a generally upward direction, intake rocker arm  26  pivots in a direction to push downwardly on intake cross-head  30 , thereby opening intake valve  22  during a predetermined portion of a combustion cycle. As such, intake cross-head  30  is configured for a predetermined range of movement during normal or routine operation of engine  10  such that intake cross-head  30  moves only as needed to open and close intake valve  22  but does not have extreme or excessive movement outside of the predetermined range of movement during routine of engine  10 . 
     Similarly, and referring still to  FIGS. 1A-5 , exhaust valve  24  is operably coupled to an exhaust rocker arm  34  which is configured to pivot or otherwise move in response to reciprocating motion of an exhaust pushrod  36 . More particularly, an exhaust cross-head  38  is positioned longitudinally intermediate a tip  40  of exhaust valve  24  and exhaust rocker arm  34 . In this way, as exhaust pushrod  36  moves in a generally upward direction, exhaust rocker arm  34  pivots in a direction to push downwardly on exhaust cross-head  38 , thereby opening exhaust valve  24  during a predetermined portion of a combustion cycle. As such, exhaust cross-head  38  is configured for a predetermined range of movement during normal or routine operation of engine  10  such that exhaust cross-head  38  moves only as needed to open and close exhaust valve  24  but does not have extreme or excessive movement outside of the predetermined range of movement during routine of engine  10 . 
     Referring to  FIG. 3 , each of rocker arms  26 ,  34  is coupled to cylinder head portion  16  with fasteners  42 . Additionally, each rocker arm  26 ,  34  includes a tappet assembly  44  configured to contact tips  32 ,  40  of intake valve  22  and exhaust valve  24 , respectively. In operation, tappet assemblies  44  are configured to contact cross-heads  30 ,  38  when opening intake valve  22  and exhaust valve  24 , respectively. To minimize any clearance between tappet assemblies  44  and cross-heads  30 ,  38  and also to minimize any clearance between cross-heads  30 ,  38  and tips  32 ,  40  of intake valve  22  and exhaust valve  24 , respectively, valvetrain assembly  20  may include a hydraulic lash adjuster (not shown) associated with each valve  22 ,  24 . The hydraulic lash adjuster is configured to accommodate any clearances between tappet assemblies  44  and cross-heads  30 ,  38  and any clearances between cross-heads  30 ,  38  and valves  22 ,  24 , respectively, to minimize noise and wear at these components during operation of valvetrain assembly  20 . 
     However, if the hydraulic lash adjuster has a failure, for example a loss of hydraulic fluid and/or pressure, or operates incorrectly, for example is slow to respond during cold temperatures, the hydraulic lash adjuster may cause excessive movement of cross-heads  30 ,  38 . More particularly, such excessive movement of cross-heads  30 ,  38  is defined as any movement of cross-heads  30 ,  38  outside of the predetermined range of movement during normal or routine operating conditions of engine  10 . In this way, if the hydraulic lash adjuster fails or operates incorrectly, engine  10  no longer operates according to normal or routine operating conditions and cross-heads  30 ,  38  may move excessively and outside of the predetermined range of movement. In such instances, if failure or incorrect operation of the hydraulic lash adjuster causes excessive movement of cross-heads  30 ,  38 , cross-heads  30 ,  38  can fall off of valve tips  32 ,  40 , respectively, leading to misfire during a combustion cycle and possible damage to engine  10 . 
     The present disclosure addresses such concerns by providing a retention member  50 , as shown in  FIGS. 1A-6 . Retention member  50  may be comprised of a metallic material and may be formed through a stamping process. For example, retention member  50  may be comprised of a steel material, such as AISI 1010 steel and/or ASTM A572 grade 50 steel. 
     It may be appreciated that retention member  50  is provided as a separate component from valvetrain assembly  20  such that retention member  50  is not defined as a part of valvetrain assembly  20 . More particularly, and as shown best in  FIG. 3 , retention member  50  is removably coupled to a portion of cylinder head portion  16  through fasteners  52 . Illustratively, fasteners  52  removably couple retention member  50  to clamp  19  of fuel injector  18  and are received through apertures  54  of retention member  50  and apertures  56  of clamp  19  and are coupled with mounting bores  58  of cylinder head portion  16 . Illustratively, fasteners  52  are threadedly coupled to cylinder head portion  16  but may be otherwise removably coupled thereto. By removably coupling retention member  50  to static components of engine  10 , such as clamp  19  and cylinder head portion  16  which do not move during operation of engine  10 , retention member  50  also is configured to maintain a static or fixed position during operation of engine  10 . As disclosed further herein, retention member  50  is not configured to contact any moving portion of engine  10 , including valvetrain assembly  20 , unless cross-heads  30 ,  38  have excessive movement or lash, in which case, retention member  50  is configured to maintain cross-heads  30 ,  38  on valve tips  32 ,  40 , respectively. 
     Retention member  50  includes a body portion  60  having apertures  54  for fasteners  52  and a plurality of arms  62  extending from body portion  60 . Illustratively, as shown in at least  FIG. 5 , body portion  60  is positioned intermediate or between valves  22 ,  24 . Body portion  60  includes an aperture  61  configured to receive a portion of fuel injector  18  therethrough. Body portion  60  also may include an alignment or guide tab (not shown) to facilitate correct positioning of retention member  50  on cylinder head portion  16 . For example, with such an alignment or guide tab, if retention member  50  is positioned incorrectly on cylinder head portion  16 , the alignment or guide tab would interfere with rocker arms  26 ,  34 . As such, during assembly of retention member  50  on cylinder head portion  16 , the alignment or guide tab ensures correct positioning of retention member  50  without interfering with other components of valvetrain assembly  20 . 
     Arms  62  of retention member  50  may be integrally formed with body portion  60  or may be coupled thereto using conventional coupling mechanisms and methods. Illustratively, retention member  50  includes four arms  62 , with two arms associated with intake valve  22  and two arms associated with exhaust valve  24 . In one embodiment, arms  62  each defines an upside-down “U” shape. More particularly, the upside-down “U” shape defines a recessed portion  64  of each arm  62 . As shown in  FIGS. 1-5 , a portion of cross-heads  30 ,  38  which positioned directly above or over valve tips  32 ,  40 , respectively, is positioned within recessed portion  64  of each arm  62  such that arms  62  are positioned directly over or above the portion of cross-heads  30 ,  38  on respective valve tips  32 ,  40 . The upside-down “U” shape of arms  62  allows arms  62  to generally extend around a portion of cross-heads  30 ,  38 , such that vertical, lateral, and rotational movement of cross-heads  30 ,  38  outside of a predetermined range of movement during normal or routine operation of engine  10  would be prevented. More particularly, if cross-heads  30 ,  38  were to move off of valve tips  32 ,  40 , respectively, during a failure or incorrect operation of engine  10 , cross-heads  38  would contact arms  62  but the shape and position of arms  62  maintains the position of cross-heads  30 ,  38  on valve tips  32 ,  40 , respectively, as disclosed further herein. 
     Referring to  FIGS. 4 and 5 , while a portion of cross-heads  30 ,  38  is positioned within recessed portion  64  of each arm  62 , arms  62  do not contact cross-heads  30 ,  38  during normal or routine operation of engine  10 . More particularly, a gap  66  is defined between arm  62  and an upper surface of cross-head  30 ,  38 . Gap  66  allows for cross-head  30 , 38  to move in the predetermined range of motion during normal or routine operation of engine  10  without any contact between cross-head  30 ,  38  and arm  62 . In one embodiment, gap  66  may be approximately 0.01-5.0 mm and, more particularly, approximately 0.1-3.0 mm. For example, gap  66  may define the smallest available clearance between cross-heads  30 ,  38  and arms  62  that allows for the predetermined range or movement of cross-heads  30 ,  38  during normal or routine operation of engine  10 , manufacturing tolerances, and expected thermal expansion of components. Additionally, it may be appreciated that retention member  50 , including body portion  60  and arms  62 , remains stationary during movement of cross-heads  30 ,  38  and does not move therewith. 
     If a failure or incorrect operation occurs with the hydraulic lash adjuster, then retention member  50  is configured to mechanically, rather than electronically or otherwise, retain cross-heads  30 ,  38  on valve tips  32 ,  40 , respectively, and prevent cross-heads  30 ,  38  from falling off of respective valve tips  32 ,  40 . More particularly, even though arms  62  do not contact cross-heads  30 ,  38  during normal or routine operation of engine  10  due to gap  66 , if the hydraulic lash adjuster fails or operates incorrectly to cause excessive movement of cross-heads  30 ,  38 , such that cross-heads  30 ,  38  contact arms  62 , the contact between arms  62  and cross-heads  30 ,  38  prevents cross-heads  30 ,  38  from falling off of valve tips  32 ,  40 , respectively. As such, the upside-down “U” shape of arms  62 , which generally extends around a portion of cross-heads  30 ,  38 , prevents rotational, lateral, and vertical movement of cross-heads  30 ,  38  relative to respective valve tips  32 ,  40  during lash. In this way, damage to engine  10  is minimized or prevented even if there is a failure or incorrect operation of the hydraulic lash adjuster. 
     It may be appreciated that the illustrative retention member  50  is configured to mechanically prevent separation of a portion of valvetrain assembly  20  from valves  22 ,  24  but is not a component of valvetrain assembly  20 . In this way, retention member  50  does not add mass to valvetrain assembly  20  which allows engine  10  to operate at an expected speed (i.e., rpm valve or range) without any additional calibrations or adjustments to engine  10  to accommodate retention member  50 . 
     While this invention has been described as having an exemplary design, the present invention may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practices in the art to which this invention pertains.