Patent Publication Number: US-2022228516-A1

Title: Metal stamped switching roller finger follower

Description:
FIELD 
     This application relates to switching roller finger followers and more specifically to a switching roller finger follower having metal stamped outer arms. 
     BACKGROUND 
     Switching rocker arms allow for control of valve actuation by alternating between two or more states, usually involving multiple arms, such as in inner arm and outer arm. In some circumstances, these arms engage different cam lobes, such as low-lift lobes, high-lift lobes, and no-lift lobes. Mechanisms are required for switching rocker arm modes in a manner suited for operation of internal combustion engines. 
     Variable valve actuation refers to manipulating the timing of valve action with respect to engine cylinders. A cylinder of an engine has a reciprocating piston. An intake valve controls when the cylinder is open to intake a charge, and an exhaust valve controls when the cylinder is open to exhaust a spent charge. Techniques include early intake valve closing (EIVC) and late intake valve closing (LIVC). “Early” and “Late” are with respect to a normal Otto cycle valve closing timing, which is near bottom dead center of piston travel. 
     Another technique deactivates the valve motion altogether, resulting in a “lost motion.” Examples of mechanisms for cylinder deactivation can be seen in WO 2014/071373, and related applications, assigned to the present applicant. The mechanisms of WO 2014/071373 are used for implementing either a valve lift event or a cylinder deactivation event. The rocker arm can either actuate a valve, or accommodate “lost motion” during a cylinder deactivation event. 
     In some examples manufacturing of such switching roller finger followers can be expensive. 
     SUMMARY 
     A switching roller finger follower (SRFF) for valve actuation includes an outer arm, a first inner arm, a bearing axle and a latch pin. The outer arm is formed of a metal stamping. The outer arm is pivotally coupled to a main axle. The first inner arm is coupled to the main axle and is pivotably secure to the outer arm. The bearing axle extends through the outer arm and the first inner arm. The bearing axle supports a roller thereon. The latch pin is slidably disposed in the outer arm and is movable between at least a first position where the outer arm and the first inner arm are coupled for concurrent rotation and a second position wherein one of the outer arm and the first inner arm are configured to rotate relative to the other arm. 
     According to other feature the SRFF further includes an upper latch cavity member and a lower latch cavity member that is coupled to the upper latch cavity member to form a latch cavity assembly that is coupled to the outer arm. The upper and lower cavity members are formed of metal stamping. The latch cavity assembly is coupled to the outer arm by at least one of welding, chemical bonding and riveting. The upper and lower latch cavity members are coupled together by at least one of welding, brazing, bonding and staking. 
     In other features the SRFF further includes an axle pin that is received by complementary holes formed in the outer arm and the latch cavity assembly. The axle pin retains the latch cavity assembly to the outer arm. The axle pin is staked to the outer arm to maintain a fixed position relative to the outer arm. The upper latch cavity member can include outwardly extending protrusions. The lower latch cavity member can define a cavity notch. The cavity notch receives the outwardly extending protrusions. The outer arm defines a rocker arm notch. The outwardly extending protrusions are further received by the rocker arm notch. The outer arm defines integrally formed axles configured to support springs. 
     According to additional features, the SRFF can include a latch cavity assembly formed of a single stamping. The latch cavity assembly is configured to be coupled to the outer arm. The outer arm further defines a latch housing integrally formed by the metal stamping. The latch housing can comprise box walls that define at least one passage that accommodate the latch pin. In one configuration, the SRRF is a single roller SRFF. The roller supported by the bearing axle is the only roller on the SRFF. The roller is configured to communicate with a single cam. The SRFF can be configured for cylinder deactivation. The SRFF is configured for variable lift. In other configurations, the SRFF further comprises a second inner arm coupled to the main axle and pivotably secured to the outer arm. The first inner arm is configured to control a main lift event through a single roller. The second inner arm has two rollers that control a secondary lift. 
     A method of forming an outer rocker arm of a switching roller finger follower (SRFF) by stamping is provided. Sheet metal is stamped into a first shape having a rocker arm structure. The stamped sheet metal is located into a fixture where the rocker arm structure is supported at least in two locations. One of the locations comprises a sphere. An insert is located into the rocker arm structure against the sphere. The insert is configured to accommodate a latch. Portions of the rocker arm structure are deflected at least partially over the insert thereby locking the insert relative to the rocker arm structure. 
     In other features the insert defines pockets thereon. Deflecting portions of the rocker arm structure further comprises deflecting the sheet metal into the pockets. The insert can be further welded to the rocker arm structure subsequent to locating the insert into the rocker arm structure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a rolling rocker arm (RRA) or switching roller finger follower (SRFF) configured for dual lift and valve deactivation and constructed with a stamped outer arm according to one example of the present disclosure; 
         FIG. 2  is a side view of the SRFF of  FIG. 1 ; 
         FIG. 3  is a sectional view taken along lines  3 - 3  of  FIG. 1 ; 
         FIG. 4A  is a sectional view taken along lines  4 A- 4 A of  FIG. 1  and shown with the actuation cams on base radius with the latch pin fully engaged resulting in all bodies latched; 
         FIG. 4B  is a sectional view of the SRFF shown in  FIG. 4A  and shown with the actuation cam rotating to lower lift and with the latch pin moved to a central position; 
         FIG. 4C  is a sectional view of the SRFF shown in  FIG. 4A  and shown during secondary lift where the main lift inner body is disengaged and a secondary lift inner body is engaged 
         FIG. 4D  is a sectional view of the SRFF shown in  FIG. 4A  and shown with the actuation cam rotated to a higher lift position and the latch pin moved to a fully disengaged position; 
         FIG. 4E  is a sectional view of the SRFF shown in  FIG. 4A  and shown during valve deactivation with both inner bodies disengaged; 
         FIG. 5A  illustrates a single RRA cooperating with a valve bridge according to another example of the present disclosure; 
         FIG. 5B  is a front view of the single RRA of  FIG. 5A ; 
         FIG. 5C  is a sectional view of the RRA of  FIG. 5A  taken along lines  5 C- 5 C of  FIG. 5A ; 
         FIG. 6  is a perspective view of a SRFF having an outer arm investment cast according to one prior art example; 
         FIG. 7  is a perspective view of a SRFF having outer arms formed of stamping according to the present disclosure; 
         FIG. 8  is a sectional view taken through the latch pin of the SRFF of  FIG. 7 ; 
         FIGS. 9A and 9B  are a rear perspective sequence view illustrating assembling of a latch cavity assembly of the SRFF of  FIG. 7 ; 
         FIGS. 10A and 10B  are a front perspective sequence view illustrating assembling of a latch cavity assembly of the SRFF of  FIG. 7 ; 
         FIGS. 11A and 11B  are a front perspective sequence illustrating assembling of the latch cavity assembly of  FIG. 9B  into the outer arm stamping; 
         FIG. 12A  is a sectional view taken along lines  12 A- 12 A of  FIG. 11B  illustrating holes pierced in the stamping of the latch cavity assembly; 
         FIG. 12B  is a perspective view of the rocker arm and latch cavity assembly of  FIG. 12A ; 
         FIG. 13  is a perspective view of the SRFF illustrating formation of a hole and insertion of an axle subsequent to inserting the latch cavity assembly into the outer arm; 
         FIG. 14A  is a sectional view taken along lines  14 A- 14 A of the SRFF of  FIG. 13 ; 
         FIG. 14B  is a perspective view of the rocker arm; latch cavity assembly and axle of  FIG. 14A ; 
         FIG. 15  illustrates a measurement step where the latch bore is measured as an assembly to maintain the relation between critical features of the SRFF; 
         FIG. 16  is a first perspective view of a stamped outer arm of a SRFF according to one example of the present disclosure; 
         FIG. 17  is a second perspective view of the stamped outer arm of  FIG. 16 ; 
         FIG. 18  is a front view of the stamped outer arm of  FIG. 16 ; 
         FIG. 19  is a front perspective view of a latch cavity assembly according to another example of the present disclosure; 
         FIG. 20  is a rear perspective view of the latch cavity assembly of  FIG. 19 ; 
         FIG. 21  is a rear perspective view of a SRFF including the stamped outer arm of  FIG. 16  and latch cavity assembly of  FIG. 19 ; 
         FIG. 22  is a front perspective view of the SRFF of  FIG. 21 ; 
         FIG. 23  is a front perspective view of a stamped outer arm of a SRFF constructed in accordance to another example of the present disclosure; 
         FIG. 24  is a side view of the stamped outer arm of  FIG. 23 ; 
         FIG. 25  is a perspective view of a SRFF constructed in accordance to one example of the present disclosure and having the stamped outer arm of  FIG. 23 ; 
         FIG. 26A  is a side view of a stamped outer rocker arm during a first assembly step; 
         FIG. 26B  is an exploded view of a stamped outer rocker arm placed into a fixture and shown with an insert positioned above, wherein a sphere is positioned for receipt of the insert; 
         FIG. 26C  is a side view of the stamped outer rocker arm subsequent to the insert being driven into the desired location controlled by the sphere; 
         FIG. 26D  is a top view of the stamped outer rocker arm and insert assembly; 
         FIG. 26E  is a rear view of the stamped outer rocker arm and insert assembly of  FIG. 26D ; 
         FIG. 27A  is a sectional view taken along lines  27 A- 27 A of  FIG. 26D ; 
         FIG. 27B  is a detail view taken around reference  27 B of  FIG. 27A ; 
         FIG. 28A  is a perspective view of the insert of  FIG. 26B ; and 
         FIG. 28B  is a front perspective view of the insert of  FIG. 28A . 
     
    
    
     DETAILED DESCRIPTION 
     As will become appreciated from the following discussion the instant disclosure provides various rocker arm configurations incorporating rocker arms that are formed of metal stamping. In some configurations, as shown in  FIGS. 7-25 , the present disclosure provides a stamped sheet metal single roller cylinder deactivation (CDA) rocker arm. As is known in the art a CDA rocker arm configuration can provide a first mode of operation that converts cam motion into valve lift and a second mode of operation where cam motion is converted to lost motion and no valve lift. 
     Depending on the configuration, typically a latch or latch pin moves between extended and retracted positions to move between lift and no lift operation. In other configurations, as shown in  FIGS. 1-5C , the present disclosure provides a stamped metal sheet roller rocker arm for dual lift and valve deactivation. The stamped construction provides advantages including cost benefits over traditional rocker arms that are formed from casting. 
     With initial reference to  FIG. 1 , a switching roller finger follower (SRFF) constructed in accordance to one example of the present disclosure is shown and generally identified at reference numeral  10 . Combination of variable valve lift (VVL) and valve deactivation capability gives an engine greater flexibility. The SRFF for dual lift and valve deactivation derives from the junction of a VVL SRFF and a deactivating SRFF. The SRFF  10  includes a first inner arm (body)  12 , a second inner arm (body)  14  and an outer arm (body)  16 . As will be described herein, the outer body  16  is a stamped metal sheet. As will become appreciated herein, prior art outer arms are formed from investment casting, metal injection molding or machined from billet steel. Additional operations such as machining and coining are required to maintain the tight tolerances needed for function. The overall cost of the outer arm is the highest cost contributor of the SRFF. The instant disclosure provides a lower cost outer arm  16  formed from a stamped metal sheet. 
     Forming an outer arm  16  of a stamped metal sheet provides many advantages. For example, stamped wall thickness can be reduced and 1.5 mm-2.0 mm are sufficient for stiffness or load carrying capacity. Lighter constructions will improve the valvetrain dynamics due to reduction in moment of inertia. Stampings have little or no sub surface defects. In contrast, investment casting and (metal injection molding (MIM) can require inspections to separate unsatisfactory parts. 
     Surface quality improvements on the wear surfaces of the stamped outer arm  16  are realized. Investment cast requires additional machining or coining operations. A stamped part has the coining and sizing operations in the same tool that forms the part. Previous limitations with similar outer arms with stamped constructions were related to latch cavity and the ability to seal oil in the latch cavity. The instant application offers the following solutions. A sealed latch cavity allows pressurized oil to be directed from the hydraulic lash adjuster to the jet hole to lubricate the bearing. The latch orientation in respect to the gothic and valve pads is flexible allowing the latch to be tilted helping with packaging, inner arm stiffness and antisubmarine issue. 
     The first inner body  12  controls the main lift event through a single (main lift) roller  20 . The second inner body  14  has two (secondary lift) rollers  22  controlling the secondary lift. Both of the first and second inner bodies  12  and  14  have a lost motion capacity that can be selected changing the position of a latch pin  26 . In normal operation, the latch pin  26  is fully engaged ( FIG. 4A ) permitting only the main lift (central cam) to open valve  30 . Moving the latch pin  26  to an intermediate position ( FIGS. 4B and 4C ) causes the first inner body  12  to become unlatched. In this condition, only the secondary lift will be operated. Moving again, the latch pin  26  to a fully disengaged position ( FIGS. 4D and 4E ). In this position, the second inner body  14  will also be unlatched permitting full valve deactivation. Control of the latch pin  26  can be operated by an external control cam  36  acting directly on through a lever system  38  on the latch pin  26 . The control cam  36  has three positions including a base radius for standard lift, mid-height for secondary lift and full height for complete unlatching and valve deactivation. 
     The first and second inner arms  12 ,  14  are pivotally coupled to the outer body  16  via a main axle  40 . The first and second inner arms  12 ,  14  are coupled to the main lift roller  20  through a bearing axle  50 . The bearing axle  50  can protrude through a slot  54  defined through the outer body  16 . The bearing axle  50  can include a “dog bone” shape to catch against a spring arm first end  60  of a spring  62 . The spring  62  biases a spring arm second end  64  against a surface of the outer body  16 . The spring  62  coils around a spring seat  70 . Spring arm first end  60  is biased to push the bearing axle  50  upwards along the slot  54  and therefore in to contact with a three lobe cam  76  as viewed in  FIG. 2 . A hydraulic lash adjuster (HLA)  80  can be arranged at a latch pin end of the SRFF  10  for accommodating lash. 
     With continued reference to  FIGS. 4A-4E , various operating conditions of the SRFF  10  are shown. In particular, when the actuation (control) cam  36  is on base radius, latch pin  26  is fully engaged ( FIG. 4A ) and all of the first inner body  12 , second inner body  14  and outer body  16  are latched. When the actuation cam  36  rotates to a lower lift ( FIGS. 4B and 4C ), the latch pin moves to a central position. During secondary lift, when the main lift inner body  12  is disengaged, the secondary lift inner body  14  remains engaged. As the actuation cam  36  rotates to a higher lift ( FIGS. 4D and 4E ), the latch pin  26  moves to a fully disengaged position. Valve deactivation occurs when both the first and second inner bodies  12  and  14  are disengaged.  FIG. 5  illustrates a solution using the SRFF  10  with a valve bridge  88 . The valve bridge  88  is engaged to valves  90  and  92 . It will be appreciated that while the latch pin  26  is shown in this example as translating as a result of an electro-mechanical actuation, other configurations such as hydraulic systems and others are contemplated within the scope of the present disclosure. 
       FIG. 6  is a perspective view of a SRFF  110  according to one prior art example. The SRFF  110  has outer arms  116  that are formed of investment casting. In comparison, the SRFF  10 A in  FIGS. 7 and 8  according to the present disclosure includes an outer am  16 A pivotally coupled to an inner arm  12 A by a main axle  40 A. 
     The SRFF  10 A is a stamped sheet metal, single roller CDA rocker arm. The outer arm  16 A of the SRFF  10 A is formed of a stamped metal sheet. Similarly, an upper latch cavity member  122  and a lower latch cavity member  124 , collectively comprising a latch cavity assembly  120  are also formed of metal stampings. In other features, the inner rocker arm  12 A can also be formed of a metal stamping. A bearing axle  50 A extends through the outer arm  16 A and the inner arm  12 A. The bearing axle  50 A supports a roller  20 A thereon. A latch pin  26 A is slidably disposed in the outer arm  16 A and is movable between at least a first position where the outer arm and the first inner arm are coupled for concurrent rotation and a second position where one of the outer arm and inner arm is configured to rotate relative to the other arm. 
     With reference to  FIGS. 9A-12B , assembling of a latch cavity (inner) assembly  120  according to one example of the present disclosure is shown. The latch cavity assembly  120  generally includes the upper latch cavity member  122  and the lower latch cavity member  124 . The upper latch cavity member  122  includes outwardly extending protrusions  126 . The lower latch cavity member  124  includes inwardly extending fingers  128  and defines a notch  129 . As best shown in  FIG. 8 , the fingers  128  can cooperate to retain features associated with the latch pin  26 A, such as, but not limited to a latch spring  131 . In some examples, a bore  133  (FIG.  15 ) is formed in the upper latch cavity member  122  to accommodate the latch pin  26 A. 
     During assembly, the notch  129  of the lower latch cavity member  124  receives the outwardly extending protrusions  126  to positively locate the upper latch cavity member  122  relative to the lower latch cavity member  124 . When assembled, the upper and lower latch cavity members  122 ,  124  form the latch cavity assembly  120 . The upper and lower latch cavity members  122 ,  124  can be held together (sealed) by way of welding, brazing, bonding, staking or combinations thereof. Once the latch cavity or inner subassembly  120  is assembled, it is mounted into the outer arm stamping  16 A ( FIG. 11A-11B ). 
     The outer arm stamping  16 A will be further described. The outer arm stamping  16 A can be formed from a single section of sheet metal. In this regard, various stamping, forming and folding operations are carried out to arrive at the structure representing the outer arm stamping  16 A. Notably, outwardly extending axles  134  are unitarily formed on the outer stamping  16 A. The axles  134  can support springs  62 A. A rocker arm notch  136  can be defined in the outer arm stamping  16 A. The rocker arm notch  136  can receive the protrusions  126  of the upper latch cavity member  122  in an assembled position ( FIG. 11B ). The inner subassembly  120  can be merged with the outer arm stamping  16 A by any suitable means such as, but not limited to, welding, chemical bonding or riveting. As shown in  FIG. 12A , holes  130  and  132  are pierced into the outer arm stamping  16 A. In some examples, the holes  130  and  132  can accommodate oil passage therethrough. 
     [ 0064 ]Turning now to  FIGS. 13-15 , additional features of the instant application are shown. A hole  150  is machined through the outer stamped arm  16 A and latch cavity assembly  120 . An axle pin  152  is fed through the outer arm  16 A and the latch cavity assembly  120 . The axle pin  152  holds the whole unit together. Explained further, the axle pin  152  further retains the latch cavity assembly  120  to the outer arm stamping  16 A. The axle pin  152  can be staked to maintain a fixed position relative to the outer stamped arm  16 A. Formation of the bore  133  is also shown in  FIG. 15 . 
       FIGS. 16-18  illustrate an outer stamped arm  16 B constructed according to additional features of the instant application. The outer stamped arm  16 B can be configured similarly to the outer stamped arm  16 A described above. Like reference numerals using a “B” suffix have been used to denote similar features.  FIGS. 19 and 20  illustrate a latch cavity assembly or inner subassembly  120 B according to additional features of the instant application. The latch cavity assembly  120 B can be formed from a single stamping. The latch cavity assembly  120 B includes protrusions  126 B that are configured to locate within the notch  136 B of the outer stamped arm  16 A. A bore  133 B is formed in the latch pin cavity assembly  120 B for accommodating features of a latch pin assembly (not shown).  FIGS. 21 and 22  illustrate the latch cavity assembly  120 B coupled to the outer stamped arm  16 B. 
       FIGS. 23 and 24  illustrate an outer stamped arm  16 C constructed according to additional features of the instant application. The stamped arm  16 C includes a latch housing  170  integrally formed by the stamped rocker arm  16 C. Explained further, the stamped rocker arm  16 C, like the other stamped rocker arms disclosed herein is formed from a series of stamping, forming, folding and joining steps. The stamped rocker arm  16 C includes box walls  172  that are folded and formed from the stamped metal sheet. In some examples, the box walls  172  can be subsequently secured, such as by welding to the outer walls of the stamped rocker arm  16 C after being folded into the position shown in  FIG. 23 .  FIG. 25  illustrates a SRFF  10 C constructed in accordance to another example of the instant application and including the outer stamped arm  16 C. The SRFF  10 C includes a latch  176  that is accommodated through passages  178  formed in the box walls  172  of the latch housing  170 . 
     Turning now to  FIGS. 26A-28B , additional features of the instant application will be described.  FIGS. 26A-26D  illustrates a stamped outer arm  16 D moving along an assembly line. At  210 , pad, holes and room for an ogive insert are completed. At  212 , the stamped outer arm  16 D is placed into a fixture  190  with precise references. A sphere  170  enters in a larger hole into the outer arm  16 D (thus giving no positioning to the outer arm  16 D). An ogive insert  172  comes from the top. The insert  172  can accommodate a latch. The ogive insert  172  is driven in the right position and further translation during the driving step is stopped and controlled by the sphere  170 . Clearances within the outer arm  16 D allow for this. When the insert  172  is in the correct position, upper portions  194  of the outer arm  16 D are bent to lock the insert  172 . As shown in  FIG. 27B , the ogive insert  172  cannot rotate. 
     As shown in  FIGS. 28A and 28B , pockets  180  on the insert  172  allow material from the upper portions  194  of the outer arm  16 D to flow inside. They constrain the ogive insert  172  in the proper position. In addition to bending, laser welding (or other welding) may be performed at interface  196  ( FIG. 26D ). The configuration shown in  FIGS. 26D-27B  provides precise control of the interaxes between the ogive center and the valve pad center. Only one component is needed to realize the ogive as opposed to two needed in prior art examples. In this example, it is not necessary to seal the ogive as it is realized inside the ogive insert. The instant manufacturing process requires low numbers of manufacturing steps to achieve the stamped outer arm. 
     For the purposes of this disclosure and unless otherwise specified, “a” or “an” means “one or more.” To the extent that the term “includes” or “including” is used in the specification or the claims, it is intended to be inclusive in a manner similar to the term “comprising” as that term is interpreted when employed as a transitional word in a claim. Furthermore, to the extent that the term “or” is employed (e.g., A or B) it is intended to mean “A or B or both.” When the applicants intend to indicate “only A or B but not both” then the term “only A or B but not both” will be employed. Thus, use of the term “or” herein is the inclusive, and not the exclusive use. See, Bryan A. Garner, A Dictionary of Modern Legal Usage 624 (2d. Ed. 1995). Also, to the extent that the terms “in” or “into” are used in the specification or the claims, it is intended to additionally mean “on” or “onto.” Furthermore, to the extent the term “connect” is used in the specification or claims, it is intended to mean not only “directly connected to,” but also “indirectly connected to” such as connected through another component or multiple components. As used herein, “about” will be understood by persons of ordinary skill in the art and will vary to some extent depending upon the context in which it is used. If there are uses of the term which are not clear to persons of ordinary skill in the art, given the context in which it is used, “about” will mean up to plus or minus 10% of the particular term. From about X to Y is intended to mean from about X to about Y, where X and Y are the specified values. 
     While the present disclosure illustrates various embodiments, and while these embodiments have been described in some detail, it is not the intention of the applicant to restrict or in any way limit the scope of the claimed invention to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention, in its broader aspects, is not limited to the specific details and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicant&#39;s claimed invention. Moreover, the foregoing embodiments are illustrative, and no single feature or element is essential to all possible combinations that may be claimed in this or a later application.