Abstract:
In a variable phased valve lifter of an internal combustion engine, a roller lifter is allowed to move along a constraining face of a constraining mechanism in a first direction, and the constraining mechanism is allowed to move freely in a second direction. As the roller lifter moves through its arcuate path, the flat surface(s) of the roller lifter will slide across the constraining face(s) of the constraining mechanism, and end members of the constraining mechanism slide fore-and-aft in at least one stationary block. 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:
CROSS REFERENCE TO RELATED APPLICATION 
   This application is related to a co-pending patent application Ser. No. 10/266,335 titled “APPARATUS AND METHOD FOR MAINTAINING CONTROLLED ORIENTATION OF A ROLLER LIFTER FOLLOWER USED IN CONJUNCTION WITH A VARIABLE PHASED VALVE LIFTER”, and filed on Oct. 8, 2002, now allowed, which is owned by the same assignee of this invention. 
   FIELD OF THE INVENTION 
   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 
   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. 
   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 
   The present invention describes a simple system for providing controlled orientation of a roller lifter in a pushrod engine using a phasing device to change the point of contact of the roller lifter on the cam. This system is applicable to single or multiple roller lifters. It also applies to roller lifters that may have curved surfaces for contacting the cam, but may not have rollers. 
   Roller lifters usually have either one or more flat surfaces machined into the outer body of the roller lifter. With the phasing mechanism described in U.S. Pat. No. 6,155,216, the arcuate motion of the roller lifter during phasing would result in excessive clearance at most positions if a fixed anti-rotation mechanism were attempted, and misalignment between cam and roller lifter could result. In the present invention the roller lifter is allowed to move along a constraining face of a constraining mechanism, and the constraining mechanism is allowed to move freely in a direction substantially parallel to a line perpendicular to the flat surface machined onto the roller lifter. As the roller lifter moves through its arcuate path, the flat surface(s) of the roller lifter will slide across the constraining face(s) of the constraining mechanism. 
   An alternative embodiment of this anti-rotation approach is to have one or more locating pins extending from the side of the lifter, perpendicular to the roller lifter longitudinal axis. These locating pins would engage slots in a constraining mechanism and the constraining mechanism would be free to move in a direction substantially perpendicular to both the longitudinal axis of the roller lifter and the axis of the locating pins. 
   Another alternative embodiment of this anti-rotation approach is to machine one or more slots into the body of the roller lifter parallel to the longitudinal axis of the lifter. Engaging pins may be inserted into these slots, the engaging pins being attached to a constraining mechanism that may move substantially perpendicular to the engaging pins and the longitudinal axis of the lifter. 
   Another alternative embodiment of this anti-rotation approach is a one-sided spring-like deformable constraining mechanism that pushes against the flat surface of a roller lifter. The constraining mechanism moves in one direction only while allowing movement of the roller lifter in the same direction as the constraining mechanism and in a direction substantially perpendicular to this direction. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       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. 
       FIG. 2  shows an isometric view of one roller lifter with substantially parallel flat surfaces with one yoke-like constraining mechanism with two sides and stationary slots into which the constraining mechanism slides of the present invention. 
       FIG. 3A  shows the objects in  FIG. 2  viewed from above, looking down the longitudinal axis of the roller lifter, where the roller lifter is shown in a position near one extreme of travel. 
       FIG. 3B  shows the same view as  FIG. 3A , but with the roller lifter now in a centered position. 
       FIG. 3C  shows the same view as  FIG. 3B , but with the roller lifter moved near to the other extreme of travel. 
       FIG. 4  shows an isometric view of a roller lifter and a two-sided yoke-like constraining mechanism with the location of the flat surfaces on the roller lifter located essentially perpendicular to their position in  FIG. 2 , where the direction of movement of the constraining mechanism is also substantially perpendicular. 
       FIG. 5  shows an isometric view of multiple lifters with a common two-sided yoke-like constraining mechanism of the present invention. 
       FIG. 6  shows an isometric view of a single roller lifter with a one-sided yoke-like constraining mechanism of the present invention. 
       FIG. 7  shows an isometric view of a single roller lifter with locating pins and a two-sided, slotted yoke-like constraining mechanism of the present invention. 
       FIG. 8  shows an isometric view of a single roller lifter with grooves in the roller lifter for orientation and a yoke-like constraining mechanism with engaging pins of the present invention. 
       FIG. 9  shows an isometric view of an alternative single-sided biasing mechanism that does not require slidably engaging slots. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   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. Referring now to  FIG. 1 , the geometry of an eccentric sleeve, in a view from the top of the roller lifter along the longitudinal axis of the roller lifter is shown. Circle  1  is the outside edge of the eccentric sleeve, 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  11  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 one roller lifter with substantially parallel flat surfaces with one yoke-like constraining mechanism with two sides and stationary slots into which the constraining mechanism slides of the present invention. Referring now to  FIG. 2 , an isometric view of a single roller lifter  10 , with roller  11  and flat surfaces  12  which are substantially parallel to each other, engaged by constraining mechanism  13  is shown. Constraining mechanism  13  is constrained by one or more stationary blocks  14 , which are attached to the engine in any number of ways known in the art. Stationary blocks  14  have slots  14   a  which receive end members  13   a  of constraining mechanism  13 . This allows fore-and-aft movement only of constraining mechanism  13 , represented by arrow  25 , when actuated by movement of roller lifter  10 . Roller lifter  10  may also move within the constraints of constraining mechanism  13  substantially perpendicular to arrow  25 , represented by arrow  26 , through the interaction of parallel flat surfaces  12  with interior members  13   b , which are also substantially parallel to each other, of constraining mechanism  13 . Allowable movement in the two substantially perpendicular directions enables the arcuate travel path of roller lifter  10  as shown in  FIG. 1 . Roller lifter  10  also moves axially up-and-down along its longitudinal axis  27  as it engages with the cam (not shown). Thus, one skilled in the art will recognize that roller lifter  10  is prevented from rotating about its longitudinal axis  27  as it moves in arcuate fashion in cooperation with constraining mechanism  13 . 
   For simplicity one stationary block  14  is omitted from this view. Having all four stationary blocks  14  provides more constraint than is absolutely necessary. Only one stationary block  14  is necessary to provide a minimum amount of constraint for roller lifter  10 . 
   Various methods may be employed to ensure that constraining mechanism  13  remains operatively engaged within slots  14   a  of stationary blocks  14  which are well known in the art. Though slots  14   a  are shown as open channels in stationary blocks  14 , slots  14   a  may also be fully contained within stationary blocks  14  in a hole-like fashion. In addition, though the end members  13   a  and interior members  13   b  of constraining mechanism  13  are shown as being square or rectangular in cross section, some or all of end members  13   a  and interior members  13   b  of constraining mechanism  13  may also be round in cross section or some other shape, or a combination of round, square, rectangular, or some other shape. 
   One skilled in the art will recognize that interior members  13   b  that mate to flat surfaces  12  must be substantially parallel to each other. Failure to be substantially parallel would cause either wedging of the lifter, or excess slop when the lifter moved in the direction indicated by arrow  26  along interior members  13   b . On the other hand, the directions of movement indicated by arrows  25  and  26  need not be substantially perpendicular to each other. As long as the movement of constraining mechanism  13  allows the orientation of roller lifter  10  to be maintained, perpendicularity of movement is not required. The limit to the lack of perpendicularity is that the movement of constraining mechanism  13  in the direction indicated by arrow  25  cannot be oriented too close to parallel to the direction of movement of roller lifter  10  along interior members  13   b  indicated by arrow  26  such that roller lifter  10  is constrained from moving through its eccentrically prescribed arc. A range from between 90° to about 30° between the orientation of the directions of movement indicated by arrows  25  and  26  should enable roller lifter  10  to move through its eccentrically prescribed arc without constraint while still being prevented from rotating about its longitudinal axis. An orientation below 30° may begin to impinge on the unconstrained eccentric movement of roller lifter  10 , and would not be desirable. 
     FIG. 3A  shows the objects in  FIG. 2  viewed from above, looking down the longitudinal axis of the roller lifter, where the roller lifter is shown in a position near one extreme of travel. Referring now to  FIG. 3A , the eccentric sleeve (not shown) is rotated approximately 60° counterclockwise from a centered position, displacing roller lifter  10 , whose center position is shown as center  10   a . The center of the roller lifter  10  will follow the arc on which center  10   a  lies as the eccentric sleeve is rotated. This eccentric sleeve rotation results in phasing of the roller  11  (not shown) on cam lobe  9  differently from the centered position. Two end members  13   a  of constraining mechanism  13  have moved into slots  14   a  of stationary blocks  14  at the top of the diagram, and the other two end members  13   a  have moved out of slots  14   a  of stationary blocks  14  at the bottom of the diagram. Flat surfaces  12  on the roller lifter  10  (appearing as edges in this view) maintain the orientation of roller  11  on roller lifter  10  with cam lobe  9 . 
     FIG. 3B  shows the same view as  FIG. 3A , but with the roller lifter now in a centered position. Referring now to  FIG. 3B , the eccentric sleeve (not shown) is in approximately its centered position, approximately 60° clockwise from its position in  FIG. 3A . The position of the center of roller lifter  10  is center  10   b.    
     FIG. 3C  shows the same view as  FIG. 3B , but with the roller lifter moved near to the other extreme of travel. Referring now to  FIG. 3C , the eccentric sleeve (not shown) is rotated approximately a further 60° clockwise from the centered position shown in  FIG. 3B . The movement of constraining mechanism  13  towards the bottom of the diagram is obvious. The position of the center of roller lifter  10  is shown as center  10   c.    
     FIG. 4  shows an isometric view of a roller lifter and a two-sided yoke-like constraining mechanism with the location of the flat surfaces on the roller lifter located essentially perpendicular to their position in  FIG. 2 , where the direction of movement of the constraining mechanism is also substantially perpendicular to that shown in  FIG. 2 . Referring now to  FIG. 4 , this embodiment of the invention shows that the direction of motion of the constraining mechanism  13 , shown by arrow  25 , is substantially perpendicular to the movement of the roller lifter  10 , shown by arrow  26 . Surfaces  12  on the roller lifter may be located at any orientation between those shown in  FIG. 2  and  FIG. 4  as long as interior members  13   b  that mate to flat surfaces  12  are substantially parallel to each other. As stated above, the directions of movement indicated by arrows  25  and  26  need not be substantially perpendicular to each other. As in  FIG. 2 , for simplicity one stationary block  14  is also omitted from this view. Only one stationary block  14  is necessary to provide a minimum amount of constraint for roller lifter  10 . 
     FIG. 5  shows an isometric view of multiple lifters with a common two-sided constraining mechanism of the present invention. Referring now to  FIG. 5 , an isometric view of multiple lifters with a common two-sided constraining mechanism  15  ensuring controlled orientation of roller lifters  10  is shown. As with the change in orientation of the constraining mechanism  13  and parallel flat surfaces  12  in  FIG. 4 , these may be oriented substantially perpendicular to the directions shown without altering the operation of the orientation of the roller lifters  10 . As in  FIG. 2 , only three stationary blocks  14  are shown, although adequate constraint, as discussed above, requires a minimum of one stationary block  14 . End members  15   a  are engaged within slots  14   a  of stationary blocks  14 , and each pair of interior members  15   b  each engage the parallel flat surfaces  12  of a roller lifter  10 . One skilled in the art will recognize that additional pairs of interior members  15   b  may be added for each additional roller lifter  10  so aligned in the engine. 
     FIG. 6  shows an isometric view of a single roller lifter with a one-sided yoke-like constraining mechanism of the present invention. Referring now to  FIG. 6 , an isometric view of a single roller lifter  10  with a one-sided constraining mechanism  16  is shown. Spring  17  pushes an interior member  16   b  of one-sided constraining mechanism  16  against a flat surface  12  of roller lifter  10  to ensure controlled orientation of roller lifter  10 , constraining movement of roller lifter  10  in the directions represented by arrows  25  and  26 , which, as stated above, need not be substantially perpendicular to each other. As in  FIG. 2 , for simplicity one stationary block  14  is also omitted from this view. Only one stationary block  14  is necessary to provide a minimum amount of constraint for roller lifter  10 . End members  16   a  are engaged within slots  14   a  of stationary blocks  14 . One skilled in the art will recognize that additional roller lifters  10  could be added along with additional interior members  16   b  similar to that shown in  FIG. 5 . 
     FIG. 7  shows an isometric view of a single roller lifter with locating pins and a two-sided, slotted yoke-like constraining mechanism of the present invention. Referring now to  FIG. 7 , an isometric view of a single roller lifter  19  with attached or integral locating pins  20  perpendicular to longitudinal axis  27  of single roller lifter  19  is shown. Two-sided, slotted constraining mechanism  18  has interior members  18   b , each having a slot  18   c  which engage each locating pin  20 . As single roller lifter  19  is moved through its arc, locating pins  20  slide in and out of slot  18   c  of interior members  18   b  of slotted constraining mechanism  18 , in a direction indicated by arrow  26 , while the end members  18   a  of slotted constraining mechanism  18  slide fore-and-aft in slots  14   a  of stationary blocks  14 , substantially perpendicular to the direction of movement of single roller lifter  19  relative to slotted constraining mechanism  18 , indicated by arrow  25 . These two constraints maintain controlled orientation of single roller lifter  19  as it moves through its arcuate path. 
     FIG. 8  shows an isometric view of a single roller lifter with grooves in the roller lifter for orientation and a yoke-like constraining mechanism with engaging pins of the present invention. Referring now to  FIG. 8 , an isometric view of a single roller lifter  21 , with grooves  22  machined along its length parallel to its longitudinal axis  27  is shown. Engaging pins  23  attached or integral to interior members  24   b  of constraining mechanism  24  maintain controlled orientation of single roller lifter  21  as it moves through its arc. Single roller lifter  21  slides back and forth against engaging pins  23  on interior members  24   b  of constraining mechanism  24  in a direction indicated by arrow  26 , while the end members  24   a  of constraining mechanism  24  slide fore-and-aft in slots  14   a  of stationary blocks  14 , substantially perpendicular to the direction of movement of single roller lifter  21  relative to engaging pins  23  on constraining mechanism  24 , indicated by arrow  25 . These two constraints maintain controlled orientation of single roller lifter  21  as it moves through its arcuate path. 
     FIG. 9  shows an isometric view of a single roller lifter with a one-sided spring-like deformable constraining mechanism of the present invention. Referring now to  FIG. 9 , an isometric view of a single roller lifter  10  and roller  11  with a one-sided constraining mechanism  30  is shown. Base  28  is attached to the internal combustion engine. Deformable member  29  is attached to base  28  at one end, and the other end engages and pushes against a flat surface  12  of roller lifter  10  to ensure controlled orientation of roller lifter  10 , constraining movement of roller lifter  10  in the directions represented by arrows  25  and  26 . Roller lifter  10  is constrained to move in a direction coincident with the deflection of deformable member  29  (arrow  25 ), and in a direction substantially perpendicular thereto (arrow  26 ), sliding along the end of deformable member  29  in contact with flat surface  12 . As stated above, the directions of movement indicated by arrows  25  and  26  need not be substantially perpendicular to each other. 
   Roller lifter  10  also moves axially up-and-down along its longitudinal axis  27  as it engages with the cam (not shown), but is prevented from rotating about longitudinal axis  27  due to the limitations on movement provided by constraining mechanism  30 . One skilled in the art will recognize that additional roller lifters  10  could be added along with additional constraining mechanisms  30  similar to that shown in  FIG. 5 . 
   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.