Patent Publication Number: US-8991349-B2

Title: Involute spring pallet component for a cylinder deactivation switchable roller finger follower

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority of U.S. 61/594,789 filed Feb. 3, 2012, which is incorporated by reference herein. 
    
    
     FIELD OF INVENTION 
     The present invention relates generally to internal combustion engines and more particularly to a method of manufacture of components of a switchable roller finger follower and to an intermediate assembly of the switchable roller finger follower. 
     BACKGROUND OF THE INVENTION 
     Various methods of producing components for internal combustion engines are known. Some common methods of manufacturing components for internal combustion engines include forming the components individually by, for example, casting or forging. After forming, these components are typically then finished by machining before or after assembly. Alternatively, components for the internal combustion engine can be formed together and then separated by, for example, fracturing, sawing, or cutting. After the components are separated, any excess material can then be removed, and the surfaces connecting the components during forming are typically machined. 
     See, for example U.S. Pat. No. 7,250,070, which is directed to a method of forming a powder metal connecting rod that has a main body and a separable cap. The main body and cap are separated from each other by fracturing the main body and the cap. To fracture the main body and the cap, a tensile force is applied at a point of fracture between the main body and cap. 
     Also, see U.S. Patent Application No. 2008/0295789 for an example of a roller finger follower for valve deactivation. 
     SUMMARY OF THE INVENTION 
     In order to make performance improvements to an internal combustion engine, for example, to reduce fuel consumption, it is desirable to control valve opening events (e.g., cylinder deactivation). Also, for a valve train with a lever system cylinder deactivation, profile switching is accomplished by creating a lever that has lost motion capabilities. 
     The present invention is directed to a method of manufacturing spring pallets of a roller finger follower and a method of manufacturing an inner arm of a roller finger follower. The present invention is also directed to an intermediate assembly of the roller finger follower. 
     Spring pallets of a roller finger follower are typically manufactured with the inner arm of a roller finger follower. However, in the present invention the spring pallets are manufactured, for example by MIM or casting, separately from the inner arm. This allows for the inner arm to be manufactured as an individual sheet metal component and the spring pallets to be manufactured separately from the inner arm as a single spring pallet unit. Throughout the manufacturing process, the spring pallets are held together by a web of material. Prior to assembly, the spring pallet unit is separated into two spring pallets, which are mirror images of each other, and the spring pallets are assembled in the roller finger follower. 
     The manufacturing process of the present invention reduces the cost and time of manufacturing as the complexity of manufacturing the inner arm and the spring pallets is reduced. Moreover, the accuracy of the spring pallets is improved as the spring pallets are formed as mirror images of each other. Further, the manufacturing process allows for adjustment of the spring pallets in a roller finger follower assembly. Thus, by not fixing the spring pallets to the inner arm, the spring pallets can be placed in a more optimal position and orientation in the roller finger follower assembly. 
     Broadly, the present invention can be defined as a method for manufacturing spring pallets, of a switchable roller finger follower. The spring pallets comprise a first spring pallet, which has a first inner surface and a second spring pallet, which has a second inner surface. The method comprises the steps of forming the first spring pallet and the second spring pallet of the switchable roller finger follower as a single unit, forming a material web between the first spring pallet and the second spring pallet, and separating the first spring pallet from the second spring pallet. 
     The first spring pallet and the second spring pallet are manufactured by casting, forging or metal injection molding. There is an additional variation of this pallet, a universal fineblanked version, where there would be no mirror images. 
     The first spring pallet and the second spring pallet are mirror images of each other. Alternatively, the first spring pallet and the second spring pallet are manufactured by fineblanking manufacturing such that the first spring pallet and the second spring pallet are not mirror images of each other. 
     The spring pallets are separated by cracking, splitting, or cutting. 
     Also, the material web holding the first spring pallet and the second spring pallet together is a seam. 
     After being separated from each other, the spring pallets can be assembled with other components of the roller finger follower. 
     Additionally, the present invention broadly relates to an intermediate assembly of a roller finger follower. The intermediate assembly comprises a first spring pallet having a first inner surface, a second spring pallet having a second inner surface, and a material web extending between the first spring pallet and the second spring pallet. The material web adjoins the first spring pallet and the second spring pallet together. 
     The spring pallets are manufactured by casting, forging or metal injection molding. 
     The first spring pallet and the second spring pallet are mirror images of each other. Alternatively, the first spring pallet and the second spring pallet are not mirror images of each other. 
     The material web holding the first spring pallet and the second spring pallet together is a seam. 
     Further, the present invention broadly relates to a method for manufacturing an inner arm of a roller finger follower, which comprises the step of forming the inner arm as a sheet metal component. The inner arm can be formed, for example, by stamping. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be further understood and appreciated by reading the following description in conjunction with the accompanying drawings, in which: 
         FIG. 1  is perspective view of a roller finger follower; 
         FIG. 2  is a perspective view of an inner arm assembly of the present invention; 
         FIG. 3  is a perspective view of a an inner arm of the present invention; 
         FIG. 4  is a perspective view of spring pallets of the present invention; and 
         FIG. 5  is a perspective view of a spring pallet unit. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates a perspective view of a roller finger follower  100   FIG. 2  illustrates an inner assembly  12  of the roller finger follower  10 . The inner assembly  12  includes an inner arm  14  and a first spring pallet  16  and a second spring pallet  18  mounted on the inner arm  14 . 
       FIG. 3  illustrates a perspective view of the inner arm  14 . The inner arm  14  is preferably manufactured as a sheet metal component that is stamped. However, any other known material or method of forming the inner arm  14 , such as forging or casting, can also be used. 
       FIG. 4  illustrates perspective views of the spring pallets  16 ,  18 . The spring pallets  16 ,  18  are mirror images of each other. 
     As shown in  FIG. 5 , the spring pallets  16 ,  18  are formed from a spring pallet  20  unit which comprises a first spring pallet  16 , a second spring pallet  18  and a seam or web of material  22 , which holds the first spring pallet  16  and the second spring pallet  18  together. The web is formed between the first spring pallet  16  and the second spring pallet  18 . Preferably, the spring pallet unit is cast, forged or metal injection molded as a single unit. However, any other known method of manufacturing the spring pallet unit can also be used. After the spring pallet unit is manufactured, the spring pallets  16 ,  18  are then separated from each other. Preferably, the spring pallet unit is cut in half to separate the spring pallets  16 ,  18  from each other. However, any other known method of separating the spring pallets  16 ,  18  can also be used, including but not limited to fracturing, sawing, or cutting. 
     By manufacturing the spring pallets  16 ,  18  as a single spring pallet unit, the cost of manufacturing and the volume of manufacturing the spring pallets  16 ,  18  and the inner arm  14  are significantly reduced. Also, the spring pallets  16 ,  18  are more accurately manufactured. 
     The present invention has been described with reference to a preferred embodiment. It should be understood that the scope of the present invention is defined by the claims and is not intended to be limited to the specific embodiment disclosed herein. 
     LIST OF REFERENCE NUMERALS 
     
         
           10  Roller Finger Follower 
           12  Inner Assembly 
           14  Inner Arm 
           16  First Spring Pallet 
           18  Second Spring Pallet 
           20  Spring Pallet Unit 
           22  Seam, Web, Material