Patent Publication Number: US-7584732-B2

Title: Shaft-mounted rocker arm arrangement

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     The present invention non-provisional patent application claims the benefit of priority to U.S. Provisional Patent Application No. 60/761,891, filed Jan. 25, 2006, and entitled “ROCKER ARM ARRANGEMENT”, which is important in-full by reference herein. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to a valvetrain for an automotive engine and, more particularly, to a valvetrain having a shaft-mounted rocker arm arrangement for an automotive internal combustion engine. 
     BACKGROUND OF THE INVENTION 
     Shaft-mounted rocker arms are configured to rotate about a rocker shaft when actuated by a camshaft to operate intake and exhaust valves. The rocker shaft is configured to support the rocker arms as they rotate. Typically, there is a rocker arm for each intake and exhaust valve. Traditionally, rocker arms include an opening where each rocker arm is inserted through the rocker shaft. The opening can be at one end of the rocker arm or in the middle of the rocker arm. 
     Assembly of traditional shaft-mounted rocker arms includes inserting each rocker arm into the rocker shaft in sequence, and placing spacers on the rocker shaft to prevent movement laterally along the rocker shaft by the rocker arms. For maintenance and repair of traditional shaft-mounted rocker arms, the rocker shaft and rocker arms must be disassembled. For example, removal and replacement of a rocker arm in the middle of the rocker shaft requires removing the entire rocker shaft and several rocker arms, as well as spacers on the rocker shaft and the like. 
     Disadvantageously, assembly and disassembly of existing of existing shaft-mounted rocker arms is challenging due to the inability to remove a rocker arm without removing the shaft and other rocker arms. Additionally, the opening in the rocker arms is typically circular, and matched to the size of the rocker shaft. This prevents the use of a formation in the rocker arm to engage a groove in the rocker shaft to locate the rocker arms on the rocker shaft because the formation would prevent the rockers arms from sliding on the rocker shaft. 
     Thus, there exists a need for a shaft-mounted rocker arrangement which overcomes these limitations. 
     BRIEF SUMMARY OF THE INVENTION 
     In various exemplary embodiments, the present invention provides a shaft-mounted rocker arm arrangement for an internal combustion engine which provides simplified assembly and disassembly by allowing individual rocker arms to be added or removed individually and without removing the rocker shaft. The present invention utilizes a rocker shaft and a rocker arm rotatably coupled to the rocker shaft. The rocker shaft includes a flat portion arranged to receive the rocker arm. The rocker arm includes a body portion and a curved arm portion arranged to match a curvature of the rocker shaft, and arranged to engage more than 180 degrees of the rocker shaft. 
     In an exemplary embodiment of the present invention, a shaft-mounted rocker arm arrangement includes a rocker arm including a body portion and a curved arm portion, and a rocker shaft including a flat portion arranged to receive the curved arm portion of the rocker arm, wherein the curved arm portion is arranged to match a curvature of the rocker shaft, and wherein the rocker arm is rotatably coupled to the rocker shaft. The curved arm portion is arranged to engaged more than 180 degrees of the rocker shaft. The rocker arm is arranged to be placed over the flat portion of the rocker shaft, and then translated axially along the rocker shaft to an operating position whereby the rocker arm is captured by the rocker shaft. Optionally, the flat portion is machined flat or formed flat. 
     In another exemplary embodiment of the present invention, a shaft-mounted rocker arm arrangement includes a rocker shaft including a flat portion and a groove, and a rocker arm including a body portion and a curved arm portion, wherein the curved arm portion comprises a formation and a curvature arranged to match a curvature of the rocker shaft, and the formation engages the groove thereby axially locating the rocker arm. The curved arm portion engages more than 180 degrees of the rocker shaft. The rocker shaft rotates in the plane established by the groove. The rocker arm is arranged to be placed over the flat portion of the rocker shaft, and then rotated about the rocker shaft to engage the formation in the groove. Optionally, the flat portion is machined flat or formed flat. 
     In yet another exemplary embodiment of the present invention, a method of mounting a rocker arm shaft includes placing the rocker arm over a flat portion on the rocker shaft, and a capturing a curved arm portion of the rocker arm with the rocker shaft, wherein in curved arm portion includes a curvature matching a curvature of the rocker shaft, and the curved arm portion engages more than 180 degrees of the rocker shaft. Optionally, the capturing step includes translating the rocker arm axially along the rocker shaft to an operating position. Alternatively, the capturing step includes rotating the rocker arm about the rocker shaft engage a formation in the curved arm portion in a groove in the rocker shaft. Optionally, the flat portion is machined flat or formed flat, and sized accordingly to allow the curved arm portion to be placed over the rocker shaft. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is illustrated and described herein with reference to the various drawings, in which like reference numbers denote like system components, respectively, and which: 
         FIGS. 1   a  through  1   d  illustrate sectional and front views of a first exemplary embodiment of a rocker arm arrangement; 
         FIGS. 2   a  through  2   c  illustrate perspective views of the first exemplary embodiment of the rocker arm arrangement; 
         FIGS. 3   a  through  3   d  illustrate sectional, top, and front views of a second exemplary embodiment of a rocker arm arrangement in accordance with the present invention; 
         FIGS. 4   a  through  4   b  illustrate perspective views of the second exemplary embodiment of the rocker arm arrangement with the rocker arm not engaged to the rocker shaft; and 
         FIGS. 5   a  through  5   b  illustrate perspective views of the second exemplary embodiment of the rocker arm arrangement with the rocker arm connected to the rocker shaft, and illustrating a first and a second operating position. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In various exemplary embodiments, the present invention provides a shaft-mounted rocker arm arrangement for an internal combustion engine which provides simplified assembly and disassembly by allowing individual rocker arms to be added or removed individually and without removing the rocker shaft. The present invention utilizes a rocker shaft and a rocker arm rotatably coupled to the rocker shaft. The rocker shaft includes a flat portion arranged to receive the rocker arm. The rocker arm includes a body portion and a curved arm portion arranged to match a curvature of the rocker shaft, and arranged to engage more than 180 degrees of the rocker shaft. 
     In an exemplary embodiment, the rocker arm is arranged to be placed over the rocker shaft flat portion and then translated axially along the rocker shaft to an operating position whereby the rocker arm is captured by the rocker shaft, and held in place on the rocker shaft with spacers. In another exemplary embodiment, the rocker shaft includes a groove, and the rocker arm includes a formation in the curvature configured to engage the groove. The rocker arm is arranged to be placed over the rocker shaft flat portion and then rotated about the rocker shaft to an operating position wherein the formation engages the groove thereby axially locating the rocker arm and wherein the rocker arm is captured by the rocker shaft. 
     Referring to  FIGS. 1   a  through  1   d , in a first exemplary embodiment of the present invention, a rocker arm arrangement  10  includes a rocker shaft  30  and a rocker arm  20  rotatably coupled to the rocker shaft  30 .  FIG. 1   a  illustrates a sectional view of the rocker arm arrangement  10  in an installation position, and  FIG. 1   b  illustrated a sectional view of the rocker arm arrangement  10  in an operating position.  FIGS. 1   c  and  1   d  illustrate from perspective views of the rocker arm arrangement  10  in the installation and operating positions. 
     The rocker arm  20  includes a body portion  24  and a curved arm portion  22  having an arc greater than 180 degrees but less than 360 degrees (as shown in  FIGS. 1   a  and  1   b ) arranged to match a curvature of the rocker shaft  30 , and arranged to engage more than 180 degrees of the rocker shaft  30 . Also, the rocker arm  20  includes a roller  26  in the body portion  24  which is actuated by a camshaft (not shown) to engage the rocker arm  20 . The roller  26  can be a needle roller bearing as is known in the art. The end of the body portion  24  can include attachment devices (not shown), such as a valve adjustment screw, to connect to the valves (not shown). As described herein, the roller  26  can also be a curved surface or the like. 
     The rocker shaft  30  includes a flat portion  32  arranged to receive the rocker arm  20 . The flat portion  32  can be machined flat or formed flat on the rocker shaft  30 . The flat portion  32  can be along the entire rocker shaft  32  or spaced along the rocker shaft  32  where the rocker arms  20  are installed. The rocker arm  20  is arranged to be placed over the rocker shaft  30  flat portion  32 , and the translated axially along the rocker shaft  30  to an operating position whereby the rocker arm  20  is captured by the rocker shaft  30 . Since the curved arm portion  22  engages more than 180 degrees of the rocker shaft  30 , once the rocker arm  20  is translated axially past the flat portion  32 , the rocker arm  20  is captured by the rocker shaft  30 . 
     In  FIG. 1   a , the rocker arm  20  is placed over the flat portion  32  of the rocker shaft  30 , allowing the curved arm portion  22  to engage more than 180 degrees of the rocker shaft  30 . The flat portion  32  is sized such that the curved arm portion  22  can be placed over the rocker shaft  30 .  FIG. 1   b  illustrates the rocker arm arrangement  10  in an operating position. Here, the rocker arm  20  has been translated axially along the rocker shaft  30 , and the curved portion  22  has been captured by the rocker shaft  30 . In the operating position, the cam shaft actuated the roller  26  causing the curved arm portion  22  to rotate on the rocker shaft  30 , and the end of the body portion  24  to engage and disengage the valves. 
       FIG. 1   c  illustrates a from perspective view of the curved portion  22  of the rocker arm  20  engaged on a portion  34  of the rocker shaft  30  during installation. The portion  34  includes the flat portion  32 . In  FIG. 1   d , the rocker arm  20  has been translated axially to a second portion  36  of the rocker shaft  30 , and the curved portion  22  has been captured by the rocker shaft  30 . 
     Referring to  FIGS. 2   a  through  2   c , perspective views of the rocker arm arrangement  10  are shown in various positions, according to an exemplary embodiment of the present invention. For the illustration purposes, only the body portion  24  and the curved arm portion  22  are shown on the rocker arm  20   FIGS. 2   a  through  2   c . The rocker arm  20  includes additional components, such as the roller  26 , a valve attachment device, and the like. 
       FIG. 2   a  illustrates the rocker shaft  30  with the flat portion  32 , and a rocker arm  20  with the curved arm portion  22  and the body portion  24 . Here, the rocker arm  20  is not attached to the rocker shaft  30 .  FIG. 2   b  illustrates the rocker arm  20  placed over the flat portion  32  of the rocker shaft  30  such that the curved portion  22  engages the rocker shaft  30 .  FIG. 2   c  illustrates the rocker arm  20  translated axially along the rocker shaft such that rocker shaft  30  captures the curved portion  22  of the rocker arm  20 . Once in this position, spacers (not shown) are added to the rocker shaft  30  to keep the rocker arm  20  from moving laterally along the rocker shaft  30  while in operation. Advantageously, this embodiment easily enables assembly and disassembly of rocker arms  20  from the rocker shaft  30 . 
     Referring to  FIGS. 3   a  through  3   d , in a second exemplary embodiment of the present invention, a rocker arm arrangement  50  includes a rocker shaft  70  and a rocker arm  60  rotatably coupled to the rocker shaft  70 .  FIG. 3   a  illustrates a sectional view of the rocker arm arrangement  50  in an installation position, and  FIG. 3   b  illustrated a sectional view of the rocker arm arrangement  50  in an operating position.  FIG. 3   c  and  3   d  illustrate front and top perspective views of the rocker arm arrangement  50 . 
     The rocker arm  60  includes a body portion  64  and a curved arm portion  62  having an arc greater than 180 degrees but less than 360 degrees (as shown in  FIGS. 3   a  and  3   b ). The curved arm portion  62  includes a formation  68 , and a curvature arranged to match a curvature of the rocker shaft  70 , and arranged to engage more than 180 degrees of the rocker shaft  70 . Also, the rocker arm  60  includes a roller  66  in the body portion  64  which is actuated by a camshaft (not shown) to engage the rocker arm  60 . The roller  66  can be a needle roller bearing as is known in the art. The end of the body portion  64  can include attachment devices (not shown), such as a valve adjustment screw, to connect to the valves (not shown). As described herein, the roller  66  can also be a curved surface or the like. 
     The rocker shaft  70  includes a flat portion  72  arranged to receive the rocker arm  60 , and a groove  74  arranged to engage the formation  68 . The flat portion  72  can be machined flat on the rocker shaft  70 . The flat portion  72  can be along the entire rocker shaft  72  or spaced along the rocker shaft  72  where the rocker arms  60  are installed. The rocker arm  60  is arranged to be placed over the rocker shaft  70  flat portion  72 , and then rotated about the rocker shaft  70  to an operating position wherein the formation  68  engages the groove  74  thereby axially locating the rocker arm  60 , and wherein the rocker arm  60  is captured by the rocker shaft  70 . In this embodiment, the rocker arm  60  is captured by the rocker shaft  70  by rotating the rocker arm  60  about the rocker shaft  70  to engage the formation  68  into the groove  74 . 
     The groove  74  and formation  68  are operable to keep the rocker arms  60  from sliding along the axis of the rocker shaft  70 . Advantageously, the groove  74  and formation  68  eliminate the need to place spacers on the rocker shaft  70  because the formation  68  engages the groove  74  to locate the rocker arm  60  in place along the rocker shaft  70 . The rocker arm  60  rotates in the plane established by the groove  74 . 
       FIG. 3   a  illustrates the rocker arm arrangement  50  in an installation position where the rocker arm  60  is placed over the flat portion  72  of the rocker shaft  70 . In this position, the curved arm portion  62  engages more than 180 degrees of the rocker shaft  70 . The flat portion  72  is sized such that the curved arm portion  62  and formation  68  can be placed over the rocker shaft  70 .  FIG. 3   b  illustrates the rocker arm arrangement  50  in an operating position. Here, the rocker arm  60  had been rotated about the rocker shaft  60  to engage the formation  68  in the groove  74  and to capture the curved arm portion  62  by the rocker shaft  70 . In this position, the camshaft actuates the roller  26  causing the curved arm portion  62  to rotate along the plane established by the groove  74 , and the end of the body portion  64  to engage and disengage the valves. 
       FIG. 3   c  illustrates a from perspective view of the curved arm portion  62  of the rocker arm  60  on the rocker shaft  70 . The groove  74  locates the rocker arm  60  axially on the shaft by engaging the formation  68  in the curved portion  62  of the rocker arm.  FIG. 3   d  illustrates a top perspective view of the rocker arm arrangement  50 . The flat portion  72  is on the opposite side as the groove  74  with the formation  68 . 
     Referring to  FIGS. 4   a  and  4   b , perspective views of the rocker arm arrangement  50  of the second exemplary embodiment of the present invention are illustrated. For illustration purposes, only the body portion  63  and the curved arm portion  62  are shown on the rocker arm  60  in  FIGS. 4   a ,  4   b ,  5   a , and  5   b . The rocker arm  60  includes additional components, such as roller  66  (shown in  FIGS. 3   a  and  3   b ), a valve attachment device, and the like. 
       FIG. 4   a  illustrates the flat portion  72  of the rocker shaft  70 , and an unattached rocker arm  60  in position to engage the flat portion  72 .  FIG. 4   b  illustrates the opposite side of the rocker shaft from  FIG. 4   a  illustrating the groove  74 , and a side view if the unattached rocker arm  60  illustrating the formation  68 . 
     Referring to  FIGS. 5   a  and  5   b , perspective views of the rocker arm arrangement  50  in a first and second operating position are illustrated. As described herein, the curved arm portion  62  of the rocker arm  60  includes the formation  68  which engages the groove  74  in the rocker shaft  70 . In  FIG. 5   a , the rocker arm  60  is rotated to a first operating position, and in  FIG. 5   b , the rocker arm is rotated to a second operating position. 
     Although the present invention has been illustrated and described herein with reference to preferred embodiments and specific examples thereof, it will be readily apparent to those of ordinary skill in the art that other embodiments and examples may perform similar functions and/or achieve like results. All such equivalent embodiments and examples are within the spirit and scope of the present invention and are intended up be covered by the following claims.