Abstract:
In a variable phased valve lifter of an internal combustion engine, two or more roller lifter are allowed to move along constraining faces of a constraining mechanism in a first direction, and the constraining mechanism is allowed to move freely in a second direction. As the roller lifters move through their parallel arcuate paths, the engaging surface(s) of the roller lifters will engage with the constraining face(s) of the constraining mechanism, and each roller lifter will prevent the other from rotating about its longitudinal axis. The roller lifter is thus prevented from rotating about its longitudinal axis as it moves in arcuate fashion in cooperation with the constraining mechanism.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to an internal combustion engine using poppet type valves to direct gases into and out of one or more cylinders or cam operated fuel injection units to inject fuel into one or more cylinders. More particularly, the orientation of a roller lifter follower in a pushrod operated engine is to be kept constant during rotation of a rotatable element to alter the phasing of the valves or injectors in the engine.  
       BACKGROUND OF THE INVENTION  
       [0002]     A description of a phasing system for roller lifter followers on a camshaft is given by Riley in U.S. Pat. No. 6,155,216, which is hereby incorporated by reference for all that is taught and disclosed therein. A description of means to maintain orientation of a roller lifter used in conjunction with a variable phase lifter is given by Riley in U.S. Pat. No. 6,932,041, which is hereby incorporated by reference for all that is taught and disclosed therein.  
         [0003]     As the rotatable element, such as an eccentric sleeve, is rotated to phase the roller lifter follower (hereinafter simply “roller lifter”), the roller lifter orientation must be controlled to allow the roller to follow the cam lobe on the camshaft. In fixed timing systems a simple pin or plate is usually sufficient to prevent the roller lifter from rotating around its longitudinal axis during operation. The arcuate path of the phased roller lifter requires an extra degree of freedom of movement. Therefore additional measures must be taken in order to maintain controlled orientation of the roller lifter.  
       SUMMARY OF THE INVENTION  
       [0004]     The present invention describes a simple system for providing controlled orientation of two or more roller lifters in a pushrod engine using a phasing device to change the point of contact of the roller lifters on the cam. It also applies to roller lifters that may have curved surfaces for contacting the cam, but may not have rollers.  
         [0005]     A description of the need for controlled orientation of roller lifters is given in U.S. Pat. No. 6,932,041. In the present invention roller lifters with the same motion caused by rotation of their respective eccentric sleeves are allowed to move through their arcuate paths, with the orientation mechanism also following the same path in one embodiment. The orientation mechanism may be located in a direction parallel to the axis of the lifter, but it is free to move in the plane perpendicular to that direction. In one embodiment the orientation mechanism will fit snugly over each lifter, as it is the action of two or more moving lifters acting on the orientation mechanism that provides the means of orientation for the other lifter(s). In another embodiment the orientation mechanism need not fit snugly, but is free to slide in a direction parallel to the orienting surfaces on the lifters. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]      FIG. 1  shows the prior art of how the geometry of rotation of an eccentric sleeve achieves transverse travel of a roller lifter on a cam lobe of a camshaft.  
         [0007]      FIG. 2  shows an isometric view of an eccentric sleeve of the prior art.  
         [0008]      FIG. 3  shows an isometric view of two roller lifters with substantially parallel flat surfaces with one yoke-like constraining mechanism with two openings that are only slightly larger than the lifters that the constraining mechanism captures.  
         [0009]      FIG. 4  shows the constraining mechanism from  FIG. 3 , and highlights the interior surfaces.  
         [0010]      FIG. 5  shows an isometric view of three roller lifters, with the outer two being constrained by a constraining mechanism, and the interior lifter not being so constrained.  
         [0011]      FIG. 6  shows an isometric view of a constraining mechanism that fits snugly over the parallel flat sides of two roller lifters, such as those in  FIG. 3 , but has a loose fit over the remaining faces of the lifters.  
         [0012]      FIG. 7  shows a yoke arrangement as in  FIG. 6  capturing two roller lifters, but with the flat sides of the lifter rotated 90° from the orientation of  FIGS. 3 and 6 .  
         [0013]      FIG. 8  shows the same arrangement as  FIG. 3  but with three lifters constrained by one yoke.  
         [0014]      FIG. 9  shows an unusual shape to the lifters and the matching shape on the constraining yoke.  
         [0015]      FIG. 10  shows a constraining yoke with pins to engage a mating slot on each of two roller lifters.  
         [0016]      FIG. 11  shows a view of the constraining yoke from  FIG. 3  with its own constraining mechanism to maintain its position in the direction parallel to the axis of the lifter and sleeve.  
         [0017]      FIG. 12  shows another embodiment of a mechanism to constrain the movement of the constraining yoke in a direction parallel to the axis of the lifter and sleeve. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]     Referring now to the Figures, in which like reference numerals refer to like components thereof,  FIG. 1  shows the prior art of how the geometry of rotation of an eccentric sleeve achieves transverse travel of a roller lifter on a cam lobe of a camshaft, and  FIG. 2  shows an isometric view of an eccentric sleeve. Referring now to  FIG. 1 , the geometry of an eccentric sleeve  10  ( FIG. 2 ), in a view from the top of the roller lifter along the longitudinal axis  11  ( FIG. 2 ) of the roller lifter is shown. Circle  1  is the outside edge of the eccentric sleeve  10 , with center  1   a , and circle  2  is the inside edge of the eccentric sleeve, with center  2   a , offset from the center  1   a  of the eccentric sleeve. Circle  3  represents the path of the center of the offset as the eccentric sleeve is rotated. Circle  4  with center  4   a  shows the position of the offset when the eccentric sleeve is rotated by some angle, here approximately 60° clockwise, around center  1   a . Similarly, circle  5  with center  5   a  shows the position of the offset when rotated the same amount, approximately 60°, in the opposite direction around center  1   a . Line  6 , between the centers  4   a  and  5   a  of circles  4  and  5  respectively, shows the distance that the center of the roller lifter (not shown) inside the eccentric sleeve  10  moves transverse to the axis of the camshaft  9   a , shown as arrow  7 . Line  8 , perpendicular to line  6 , is the farthermost distance to circle  3 . Circle  2  corresponds to the outer location of a roller lifter that would make contact with cam lobe  9 . Line  8  represents the maximum fore-and-aft movement of the roller lifter along the axial direction of camshaft  9   a , parallel to arrow  7 .  FIG. 2  shows an isometric view of eccentric sleeve  10  with its longitudinal axis  11  corresponding to center  1   a  in  FIG. 1 .  
         [0019]      FIG. 3  shows an isometric view of two roller lifters with substantially parallel flat surfaces with one yoke-like constraining mechanism with slots into which the two roller lifters fit of the present invention. Referring now to  FIG. 3 , an isometric view of two roller lifters  12   a  and  12   b , with rollers  13   a  and  13   b  and flat surfaces  14   a  and  14   b  which are substantially parallel to each other, engaged by constraining mechanism  15  is shown. Any tendency by roller lifter  12   a  to rotate about its longitudinal axis  16   a  will be countered by the inability of roller lifter  12   b  to rotate about longitudinal axis  16   a  of roller lifter  12   a , and vice versa for roller lifter  12   a  attempting to rotate about longitudinal axis  16   b  of roller lifter  12   b  due to the mutual constraint provided by constraining mechanism  15 . This requires that each eccentric sleeve  10  (see  FIG. 2 ) that surrounds each group of jointly constrained roller lifters ( 12   a  and  12   b  here) has the same angular displacement of the center of the lifter bore (longitudinal axes  16   a  and  16   b ) from the center of the each sleeve (longitudinal axis  11  in  FIG. 2 ).  
         [0020]      FIG. 4  shows an isometric view of constraining mechanism  15  from  FIG. 3 . Referring now to  FIG. 4 , the constraining mechanism  15  contains two apertures  17   a  and  17   b  that capture roller lifters  12   a  and  12   b  respectively (see  FIG. 3 ) whose parallel sides  18   a  and  18   b  fit closely over the parallel flat surfaces  14   a  and  14   b  of roller lifters  12   a  and  12   b  (see  FIG. 3 ), and whose curved sides  19   a  and  19   b  fit closely over the curved portions of roller lifters  12   a  and  12   b  (see  FIG. 3 ). Parallel sides  18   a  and  18   b  and curved sides  19   a  and  19   b  are the inside edges of apertures  17   a  and  17   b  of constraining mechanism  15 , and are substantially flat and aligned substantially parallel with longitudinal axes  16   a  and  16   b  and flat surfaces  14   a  and  14   b  of roller lifters  12   a  and  12   b . When roller lifters  12   a  and  12   b  move through their parallel arcuate paths, each point on constraining mechanism  15  moves through the same path, and maintains the orientation of roller lifters  12   a  and  12   b  with respect to their respective longitudinal axes  16   a  and  16   b.    
         [0021]     One skilled in the art will recognize that roller lifters  12   a  and  12   b  could each have just one flat surface  14   a  and  14   b , and corresponding constraining mechanism  15  would have within apertures  17   a  and  17   b  only one flat surface  18   a  and  18   b . Also, the flat surfaces  14   a / 14   b  for one roller lifter  12   a / 12   b  and flat surfaces  18   a / 18   b  for apertures  17   a / 17   b  could be on the same side in relation to each other, or on opposite sides in relation to each other.  
         [0022]      FIG. 5  shows an isometric view of a constraining mechanism orienting two roller lifters on either side of another roller lifter that is not being constrained by the same mechanism. Referring now to  FIG. 5 , the constraining mechanism  20   a  with extension member  20   b  captures roller lifters  12   a  and  12   c , with roller lifter  12   b  not captured because extension member  20   b  does not touch roller lifter  12   b . This allows orientation of roller lifters  12   a  and  12   c  with respect to each others&#39; longitudinal axes  16   a  and  16   c , but allows roller lifter  12   b  to orient independently about its longitudinal axis  16   b.    
         [0023]      FIG. 6  shows an isometric view of a constraining mechanism with elongated apertures compared to the close-fitting apertures shown in  FIGS. 3 and 4 . Referring now to  FIG. 6 , the constraining mechanism  21  contains two apertures  22   a  and  22   b  whose parallel sides  23   a  and  23   b  fit closely over the parallel flat surfaces  14   a  and  14   b  (see  FIG. 3 ) of roller lifters  12   a  and  12   b  (see  FIG. 3 ), and whose other loose fitting sides  24   a  and  24   b  do not fit closely over the curved surfaces of roller lifters  12   a  and  12   b  (see  FIG. 3 .) This additional clearance to the curved surfaces allows constraining mechanism  21  to slide freely back and forth in a direction parallel to arrow  25 . Thus when roller lifters  12   a  and  12   b  move through their parallel arcuate paths, constraining mechanism  21  maintains the orientation of roller lifters  12   a  and  12   b  with respect to their longitudinal axes  16   a  and  16   b  (see  FIG. 3 ) without having to follow exactly the same arcuate path.  
         [0024]      FIG. 7  shows an isometric view of two roller lifters captured by a constraining mechanism with the location of the flat surfaces on the roller lifter located essentially perpendicular to their position in  FIG. 3 , where the direction of movement of the constraining mechanism is also substantially perpendicular to that shown in  FIG. 6 . Referring now to  FIG. 7 , this embodiment of the invention shows roller lifters  26   a  and  26   b  with flat surfaces  27   a  and  27   b  that are substantially perpendicular to flat surfaces  14   a  and  14   b  on roller lifters  12   a  and  12   b  in  FIG. 3 . In addition, constraining mechanism  28  is free to slide back and forth in a direction parallel to arrow  29 , substantially perpendicular to the movement of constraining mechanism  21 , shown by arrow  25  in  FIG. 6 . Flat surfaces  14   a  and  14   b  on roller lifters  12   a  and  12   b  and surfaces  27   a  and  27   b  on roller lifters  26   a  and  26   b  may be located at any orientation between those shown in  FIG. 3  and  FIG. 7  as long as the interior mating edges of the constraining mechanism to these flat surfaces are substantially parallel to each other.  
         [0025]      FIG. 8  shows an isometric view of three lifters with a single constraining mechanism of the present invention. Referring now to  FIG. 8 , an isometric view of multiple lifters with a common, close-fitting constraining mechanism  30  ensuring controlled orientation of all three roller lifters  12   a ,  12   b  and  12   c  is shown. One skilled in the art will recognize that any number of lifters greater than two may be constrained in this manner. Similarly the orientation of the apertures of the constraining mechanism may be varied as shown above.  
         [0026]      FIG. 9  shows an isometric view of two roller lifters with a constraining mechanism containing arbitrary shaped apertures of the present invention. Referring now to  FIG. 9 , an isometric view of two roller lifters  31   a  and  31   b  with a constraining mechanism  32  is shown. The shape at the upper end of roller lifters  31   a  and  31   b  is intended to indicate any arbitrary or irregular geometry with sides parallel to roller lifter longitudinal axes  33   a  and  33   b . Similarly there are correspondingly shaped apertures in constraining mechanism  32  that capture roller lifters  31   a  and  31   b  to maintain their orientation with respect to lifter longitudinal axes  33   a  and  33   b . One skilled in the art will recognize that additional arbitrary shapes to the upper portions of roller lifters  31   a  and  31   b  and corresponding shaped apertures to constraining mechanism  32  could be substituted and still perform the functionality of constraining the orientation of the roller lifters.  
         [0027]      FIG. 10  shows an isometric view of two roller lifters with locating slots and a constraining mechanism of the present invention with matching tangs to fit the slots. Referring now to  FIG. 10 , an isometric view of two roller lifters  34   a  and  34   b  with longitudinal slots  35   a  and  35   b  parallel to longitudinal axes  36   a  and  36   b  of roller lifters  34   a  and  34   b  is shown. Constraining mechanism  37  has two tangs  38   a  and  38   b  that engage with longitudinal slots  35   a  and  35   b  of roller lifters  34   a  and  34   b  and so maintain controlled alignment of roller lifters  34   a  and  34   b  about their longitudinal axes  36   a  and  36   b.    
         [0028]      FIG. 11  shows an isometric view of a means of constraining the constraining mechanism of the present invention. Referring now to  FIG. 11 , an isometric view of constraining mechanism  39  is shown. It should be apparent that constraining mechanism  39  is the same geometry as constraining mechanism  15  from  FIG. 3 , but with an arcuate fastener slot  40  parallel to the paths that the longitudinal axes  16   a  and  16   b  of roller lifters  12   a  and  12   b  from  FIG. 3  would follow when moved by an eccentric sleeve (see  FIG. 2 ). A fastener  41  acts to constrain constraining mechanism  39  from moving in a direction parallel to longitudinal axes  16   a  and  16   b . Fastener  41  attaches to block  42  which is considered to be part of the structure containing the eccentric sleeves and lifters (not shown). Fastener  41  may contain a spacer or other mechanical separator that prevents fastener  41  from restricting the ability of constraining mechanism  39  from moving in a plane perpendicular to longitudinal axes  16   a  and  16   b . To anyone skilled in the art, it should be obvious that fastener slot  40  may have a large variety of shapes, provided that fastener  41  is capable of providing the necessary constraint to prevent constraining mechanism  39  from moving out of its plane of movement perpendicular to longitudinal axes  16   a  and  16   b.    
         [0029]      FIG. 12  shows an isometric view of a means of constraining the constraining mechanism of the present invention. Referring now to  FIG. 12 , an isometric view of constraining mechanism  15  is shown. Now instead of having fastener  41  penetrating constraining mechanism  15 , fastener  43  secures tab  44  to block  45 , which is considered to be part of the structure containing the eccentric sleeves and lifters (not shown). Tab  44  and block  45  act to constrain the movement of constraining mechanism  15  in a plane perpendicular to longitudinal axes  16   a  and  16   b . This results in constraining mechanism  15  allowing roller lifters  12   a  and  12   b  to move freely in the direction of their longitudinal axes  16   a  and  16   b , and when roller lifters  12   a  and  12   b  are rotated about said axes by simultaneous rotation of like phased eccentric sleeves (not shown) constraining mechanism  15  is free to slide between tab  44  and block  45 , maintaining the required orientation of roller lifters  12   a  and  12   b.    
         [0030]     Having described the present invention, it will be understood by those skilled in the art that many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the present invention.