FINGER FOLLOWER

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of U.S. Provisional Patent Application

Serial No. 63/175,753, filed April 16, 2021 . The above-identified application is hereby incorporated by reference as if fully set forth in its entirety.

FIELD

[0002] This application relates to switching roller finger followers and more specifically to a switching roller finger follower having a metal sheet stamped outer body.

BACKGROUND

[0003] 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.

[0004] 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. [0005] 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.

[0006] In some examples manufacturing of such switching roller finger followers can be expensive. Commonly used technology for manufacturing outer bodies of switching roller finger followers include investment casing or metal injection molding (MIM). These techniques are expensive due to the operation itself and the necessity of further machining the part.

SUMMARY

[0007] A switching roller finger follower (SRDD for valve actuation includes an outer arm assembly, an inner arm, a bearing axle and a latch pin. The outer arm assembly can be pivotally coupled to a main axle. The outer arm assembly can comprise a main body and a latch pin body. The inner arm can be coupled to the main axle and be pivotably secured to the outer arm assembly. The bearing axle can extend through the outer arm assembly and the first inner arm. The bearing axle can support a roller thereon. The latch pin can be slidably disposed in the outer arm and be 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 am and the first inner arm can be configured to rotate relative to the other of the outer arm and the first inner arm. The main body and the latch pin body can both be formed of a metal stamping. [0008] According to other features, the main body can include outer side arms. The outer side arms can define grooves thereon. The grooves can have a square profile. The main body can define a plurality of apertures therethrough. The apertures of the plurality of apertures can beach define a square profile. The latch pin body can comprise a forward body portion, a rearward body portion and an upper body portion. The upper body portion can include extension portions. The extension portions of the latch pin body can have a square profile and be received by the grooves of the main body portion. The extension portions can be staked into the grooves of the main body portion. The latch pin body can include a plurality of pins extending therefrom.

[0009] According to still other features, the pins of the plurality of pins each have a square profile and are received by the respective apertures of the main body portion. The pins can be staked into the apertures of the main body portion. The SRFF can be a single roller SRFF. The roller supported by the bearing axle can be the only roller on the SRFF. The roller can be configured to communicate with a single cam. The SRFF can be configured for cylinder deactivation.

[0010] A switching roller finger follower (SRFF) for valve actuation constructed in accordance to additional features includes an outer arm assembly and an inner arm. The outer arm assembly can be pivotally coupled to a main axle. The outer arm assembly can include a main body formed of metal stamping and a latch pin body formed of metal stamping. The inner arm can be coupled to the main axle and be pivotably secured to the outer arm assembly. The main body can include outer side arms that extend relative to a front support platform configured as a slider acting on a tip of the valve and a rear support platform configured as an interface for a hydraulic lash adjuster. Each side arm of the outer side arms can define a groove. The rear support platform can define a plurality of apertures. The latch pin body can comprise a forward body portion, a rearward body portion and an upper body portion. The upper body portion can define extension portions that locate into respective grooves defined on the outer side arms. The forward body portion and the rearward body portion can include pins that are received into the respective apertures defined on the rear support platform. The extension portions can be staked into the respective grooves. The pins can be staked into the respective apertures.

[0011] A method of forming an outer rocker arm of a switching roller finger follower (SRFF) by stamping is provided. A first metal sheet is stamped into a first shape having a main body structure of the outer rocker arm. Portions of the first sheet metal are deflected to form a main body having outer side arms relative to a front support platform and a rear support platform. A second metal sheet can be stamped into a second shape having a latch pin body structure of the outer rocker arm. Portions of the second sheet metal can be deflected to form a latch pin body having a forward body portion, a rearward body portion and an upper body portion. The latch pin body can be located relative to the main body. Pins extending from the latch pin body can locate into respective apertures defined in the main body. Wings extending from the latch pin body locate into grooves defined in the main body. The latch pin body is staked to the main body.

[0012] In additional features, the pins are axial staked to the main body. The wings are axial staked to the main body.

BRIEF DESCRIPTION OF THE DRAWINGS [0013] FIG. 1 is a front perspective view of a rolling rocker arm (RRA) or switching roller finger follower (SRFF) configured for valve deactivation and constructed with a stamped outer body assembly according to one example of the present disclosure;

[0014] FIG. 2 is a rear perspective view of the SRFF of FIG. 1 ;

[0015] FIG. 3 is a front perspective view of a main body of the outer body assembly of FIG. 1 ;

[0016] FIG. 4 is a rear perspective view of the main body of FIG. 3;

[0017] FIG. 5 is a side view of the main body of FIG. 3;

[0018] FIG. 6 is a bottom view of the main body of FIG. 3;

[0019] FIG. 7 is a first perspective view of a latch pin body of the outer body assembly of FIG. 1 ;

[0020] FIG. 8 is a second perspective view of the latch pin body of FIG. 7;

[0021] FIG. 9 is a rear perspective exploded view of the outer body assembly of FIG. 1;

[0022] FIG. 10 is a front perspective exploded view of the outer body assembly of FIG. 9;

[0023] FIG. 11 is a top perspective exploded view of the outer body assembly of FIG. 9;

[0024] FIG. 12 is a front perspective exploded view of the outer body assembly prior to advancing the latch pin body into engagement with the main body; [0025] FIG. 13 is a front perspective view of the outer body assembly in an assembled position;

[0026] FIG. 14 is a rear perspective view of the outer body assembly of FIG.

13; [0027] FIG. 15 is a side perspective view of the outer body assembly of FIG. 13 subsequent to two axial staking events on an upper section of the outer body assembly; and

[0028] FIG. 16 is a bottom perspective view of the outer body assembly of FIG. 15 subsequent to four axial staking events on a lower section of the outer body assembly.

DETAILED DESCRIPTION

[0001]As will become appreciated from the following discussion, the instant disclosure provides a metal sheet stamped and assembled outer body assembly for a switching roller finger follower (SRFF). In the example shown, the SRFF is configured for use in a 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. The outer body assembly comprises a main body and a latch pin body that are coupled together by an axial staking process. The SRFF configuration disclosed herein provides a low cost solution for manufacturing large volume components. The stamped construction provides advantages including cost benefits over traditional rocker arms that are formed from casting.

[0002] 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. The SRFF 10 includes an inner arm or inner body 12, and an outer arm or outer arm assembly 16. As will be described herein, the outer arm assembly 16 collectively comprises a main body 20 and a latch pin body 22. The main body 20 and the latch pin body 22 are both formed from a stamped metal sheet and subsequently joined together as the outer arm assembly 16 by a staking process. 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 body assembly 16 formed from a stamped metal sheet.

[0003] Constructing the outer arm assembly 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 also 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 assembly 16 are realized. Investment casting 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 having stamped constructions were related to latch cavity challenges 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 challenges. [0004] The inner arm 12 controls the main lift event through a single (main lift) roller 24. The inner arm 12 has a lost motion capacity that can be selected by changing the position of a latch pin 26. In normal operation, the latch pin 26 is fully engaged permitting a cam to open a valve 30 (FIGS. 1 and 2). When the latch pin 26 is moved to a fully disengaged position, the inner arm 12 will be unlatched permitting full valve deactivation. Control of the latch pin 26 can be operated by an external control cam (not particularly shown) acting directly on through a lever system (not particularly shown) on the latch pin 26. It will be appreciated that while the example discussed herein is for a single inner arm configuration, the same may be applied to an SRFF having first and second inner arms for use in a variable valve lift (VVL) configuration. As is known, by incorporating two inner arms, the SRFF can be configured for dual lift applications.

[0005] The inner arm 12 and the outer body assembly 16 are pivotally coupled via a main axle 40. The inner arm 12 is coupled to the main lift roller 24 through a roller or 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 hooks 66 configured on the outer body assembly 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 cam lobe (not particularly shown). A hydraulic lash adjuster (FILA) 80 can be arranged at a latch pin end of the SRFF 10 for accommodating lash.

[0006] Turning now to FIGS. 3-6, the main body 20 will be further described. The main body 20 is a stamped metal sheet that is formed from a series of stamping, forming and folding steps. No machining steps are needed. The main body 20 includes outer side arms 100 formed from the stamped metal sheet that are folded relative to a front support platform 102, that ultimately becomes a slider acting on a tip of the valve 30 and rear support platform 104 having a semispherical pivot area that ultimately becomes the HLA interface. The outer side arms 100 define grooves 110 thereon. In the example shown, the grooves 110 have a square profile. Four square apertures 120 (best shown in FIG. 6) are defined on the main body 20 at the rear support platform 104. In the example shown, the slot 54 comprises a flat top surface 126 (FIG. 5).

[0007] With reference now to FIGS. 7 and 8, the latch pin body 22 will be further described. The latch pin body 22 is a U-shaped element whose function is to support the latch pin 26 permitting a free stroke. The latch pin body 22 is formed from a stamped metal sheet. Like the main body 20, the latch pin body 22 can be formed from a series of stamping, forming, and joining steps. No machining steps are needed. The latch pin body 22 includes a forward body portion 130, a rearward body portion 132 and an upper body portion 134. The upper body portion 134 includes extension portions or wings 150. In the example shown, the wings 150 have a squared profile to complement the geometry of the grooves 110 on the main body 20. Four pins 152 extend from the latch pin body 22. The four pins 152 have a square geometrical profile. Latch pin holes 154 are defined through the forward and rearward body 130, 132.

[0008]With reference now to FIGS. 12-16, assembly of the latch pin body 22 and the main body 20 will be described. At the outset, the latch pin body 22 is located relative to the main body 20 as shown in FIG. 12. Next, the latch pin body 22 is advanced generally between the outer side arms 100 of the main body 20 into the position shown in FIG. 13. During the advancement, the four pins 152 extending from the latch pin body 22 locate into the four complementary apertures 120 defined on the main body 20 (see FIG. 16). Concurrently, the wings 150 extending from the latch pin body 22 locate into the complementary grooves 110 defined on the main body 20.

[0009] Once the latch pin body 22 is located into a received position shown in FIGS. 13 and 14, an axial staking process is conducted. In this regard, in no particular order, the pins 152 are staked, causing the pins 152 to join and be coupled to the main body 20 at the apertures 120. Explained further, an impact force is administered onto the pins 152 generally along an axis of the pins 152 causing material of the pins to be urged outwardly (such as in a direction transverse to the axis of the pins 152 indicated at arrows F1 , FIG. 16) and into the main body 20 at the apertures 120 in the rear support platform 104. The staking of the pins 152 vertically locks the latch pin body 22 to the main body 20. Similarly, the wings 150 are staked causing the wings 150 to join and be coupled to the main body 20 at the grooves 110. Again, in examples, an impact force (such as in a direction indicated at arrows F2, FIG. 15) can be administered onto the wings 150 causing material of the wings 150 to be urged into contact with the respective outer side arms 100 at the grooves 110. The staking of the wings 150 horizontally locks the latch pin body 22 to the main body 120 to preclude side motion of the latch pin body (in a direction parallel to the arms 100).

[0010] 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.

[0011] 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’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.