Abstract:
An improved cam shaft configuration for internal combustion engines is provided wherein the oil is efficiently diverted from the camshaft cap to adjacent camshaft lobes. A reorientation of the camshaft oil diverter improves the distribution and increases the quantity of oil flow without building in additional oil passages to supply oil to cams, that would introduce additional expense without substantially alleviating existing prior art lubrication deficiency problems. The invention obviates the known prior art configurations that suffer from the drawback of insufficient distribution of lubricating oil to adjacent camshaft lobes that is effected by oil diverter configurations.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to an improved lubricating device for the cam lobes of camshafts in an internal combustion engine.  
       BACKGROUND OF THE INVENTION  
       [0002]     A typical concern with valve train lubrication in internal combustion engines is assuring the furnishing of an adequate supply of oil on the cam lobes while the engine is operating at all engine conditions. When the camshaft, particularly in an overhead cam engine, is operating, it is critical that the cam lobes are well lubricated. Lubricating is typically done using the engine oil. Without adequate oil supply to the cam lobes, components can overheat and fail. Accordingly, an adequate supply of oil to lubricate the lobes is critical to an engine under all operating conditions and engine speeds, including low engine speeds.  
         [0003]     An example of one current method of supplying oil is to allow oil to bleed off out of top holes in lash adjusters through holes in roller finger followers. The oil then flows by gravity along the top surface of the body of the roller finger follower toward the areas in need of lubrication. While this works acceptably for some geometries of cam and roller configurations, oil does not always flow properly for all configurations.  
         [0004]     A difficulty occurs with those geometries of overhead cam engines when one of the two sets of valves is located above all but the valve contacting tip portion of the roller finger followers such that gravitational force will cause the oil to flow away from rather than toward the critical areas in need of lubrication. In other words, the oil will flow off of the roller finger follower and down to the tappet gallery floor, thus providing no lubrication to the cam lobes and roller of the roller finger follower.  
         [0005]     Some attempted solutions to this problem include adding extra oil passages around the cams to supply oil directly to the cam lobes, at the added cost, added for weight for additional parts and loss of oil pressure in the overall system; or by adding parts that force oil to be sprayed onto the cams at the expense of additional parts and the resultant loss of oil pressure in the overall oil system. A prior art attempt to remedy the inadequacy in a 90 degree V-type automotive engine was found to divert an insufficient quantity of oil, to the camshaft lobe. Thus, a need exists for an oiling mechanism that will assure adequate oil supply to the cam lobes at all engine speeds while not losing oil pressure or adding significant cost increases.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention contemplates an oiling mechanism for use in an internal combustion engine having a camshaft that includes a journal portion having oil supplied to its surface and a cam lobe portion. The oiling mechanism is comprised of at least one camshaft bearing member affixed to the engine about the camshaft journal portion. The oiling mechanism comprises a diverter affixed to the camshaft bearing member provided adjacent to the camshaft journal, whereby oil will be diverted from the camshaft journal toward the cam lobe.  
         [0007]     An object of the present invention is to provide a mechanism for supplying an improved quantity of oil to the camshaft lobes of a camshaft in an engine that includes a diverter affixed to the camshaft bearing members.  
         [0008]     Another object of the present invention is providing adequate oil supply to the cam lobes while not adding additional parts to the system.  
         [0009]     An additional object of the present invention is to provide an arrangement that assures an adequate oil supply without losing pressure in the oil system at all engine speeds.  
         [0010]     Additional objects and advantages will be apparent from the following detailed description. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is an elevation view illustrating in partial section of a prior art engine.  
         [0012]      FIG. 2  is a partial plan view of a prior art cylinder head of a single overhead cam engine, with the lash adjusters not shown.  
         [0013]      FIG. 3  is an elevation view in partial section of an engine in accordance with the present invention.  
         [0014]      FIG. 4  is a partial plan view of a cylinder head of a single overhead cam engine with lash adjusters not shown, in accordance with the present invention.  
         [0015]      FIG. 5  is a side elevation view of a prior art camshaft bearing cap shown inclined as it would be in a 90 degree V-type engine.  
         [0016]      FIG. 6  is a plan view of a camshaft bearing cap of  FIG. 5 .  
         [0017]      FIG. 7  is a side elevation view of a prior art camshaft bearing cap shown inclined as it would be in a 90 degree V-type engine.  
         [0018]      FIG. 8  is a plan view of the camshaft bearing cap of  FIG. 7 .  
         [0019]      FIG. 9  is a side elevation view of a camshaft bearing cap with oil diverter pad re-oriented in accordance with the present invention, shown inclined as it would be in a 90 degree V-type engine.  
         [0020]      FIG. 10  is a plan view of a camshaft bearing cap of  FIG. 9 .  
         [0021]      FIG. 11  is a side elevation view of an alternative camshaft bearing cap in accordance with the present invention, shown inclined as it would be in a 90 degree V-type engine.  
         [0022]      FIG. 12  is a plan view of a camshaft bearing cap of  FIG. 11 .  
         [0023]      FIG. 13  is a plan view of a prior art camshaft bearing cap and camshaft illustrating the flow of oil.  
         [0024]      FIG. 14  is an isometric view of a camshaft bearing cap and camshaft of  FIG. 13  shown inclined as it would be in a 90 degree V-type engine illustrating the flow of oil.  
         [0025]      FIG. 15  is a plan view of a prototype prior art camshaft bearing cap and a camshaft illustrating the flow of oil.  
         [0026]      FIG. 16  is an isometric view of a camshaft bearing cap and camshaft of  FIG. 15 , inclined as it would be in a 90 degree V-type engine illustrating the flow of oil.  
         [0027]      FIG. 17  is a plan view of a camshaft bearing cap and a camshaft in accordance with the present invention illustrating the flow of oil.  
         [0028]      FIG. 18  is an isometric view of a camshaft bearing cap and camshaft in accordance with the present invention showing the camshaft bearing cap inclined as it would be in a 90 degree V-type engine illustrating the flow of oil.  
         [0029]      FIG. 19  is a plan view of an alternative camshaft bearing cap and a camshaft in accordance with the present invention illustrating the flow of oil.  
         [0030]      FIG. 20  is an isometric view of a camshaft bearing cap of  FIG. 19  showing the camshaft bearing cap inclined as it would be in a 90 degree V-type engine illustrating the flow of oil.  
         [0031]      FIG. 21  is an elevation of a camshaft bearing cap and a camshaft of the kind shown in  FIG. 17  and partially rotated illustrating the flow of oil when the camshaft is rotating in the opposite direction as compared to  FIG. 17 .  
         [0032]      FIG. 22  is an isometric view of a camshaft bearing cap and a camshaft of  FIG. 21  inclined as it would be in a 90 degree V-type engine and illustrating the flow of oil.  
         [0033]      FIG. 23  is an elevation of a camshaft bearing cap and a camshaft of the kind shown in  FIG. 19  and partially rotated illustrating the flow of oil when the camshaft is rotating in the opposite direction as compared to  FIG. 19 .  
         [0034]      FIG. 24  is an isometric view of a camshaft bearing cap and camshaft of  FIG. 23  showing the camshaft bearing cap inclined as it would be in a 90 degree V-type engine illustrating the flow of oil. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0035]     Referring to  FIGS. 1 and 2 , a portion of an internal combustion engine  20  is shown having a single overhead camshaft  36 . Conventional intake valves  22  and exhaust valves (not shown), are mounted in a cylinder head  27 , each of which has a head located within one of the cylinders  26  of engine  20 . Each of the valves  22  is biased in a closed position (although illustrated in the open position) by a spring  28 . A roller finger follower  30  is in surface contact with the back end of each of the valves. Each of the roller finger followers  30  has a roller  32 , in contact with either an intake cam lobe  34  or an exhaust cam lobe  35  (shown in  FIG. 2 ) on the camshaft  36 , and an adjustment portion  38  that is often referred to as a “ball socket” into which the end of a lash adjuster seals and that is in surface contact with the lash adjuster  40 . Each of the rollers  32  includes a series of needle bearings  33  to promote rotation of rollers  32 .  
         [0036]     Each lash adjuster  40  includes a top hole  41 , shown in  FIG. 1  through which oil bleeds off and then runs along the top surface  42  of the stamped body  44  of the corresponding roller finger follower  30  under a gravitational force. The top hole  41  of the roller finger follower  30  associated with the exhaust valves (not shown) is positioned vertically higher than the line of contact between the exhaust cam lobes  35  and the rollers  32  while the top hole  41  of the roller finger follower  30  associated with the intake valves  22  is vertically below the line of contact between the intake cam lobes  34  and the rollers  32 .  
         [0037]     With an engine configuration of this kind, the oil that bleeds off of the lash adjusters  40  associated with the exhaust valves (not shown) will then run down to and wet the surfaces of roller  32 . As this occurs, the contact between the rollers  32  and the associated intake cam lobes  34  will be constantly wetted with oil. On the other hand, the oil that bleeds off of the lash adjusters  40  associated with the intake valves  22  will run down to the tappet gallery floor, thus providing no lubrication to the intake cam lobes  34  and roller  32  of the roller finger followers  30  from this supply of oil.  
         [0038]     Surrounding the top portion of and retaining the camshaft  36  are camshaft bearing caps  50 . The bearing caps  50  are located adjacent to the cam lobes  34 . The bearing caps  50  are in proximate surface contact with the camshaft journal  46 , having only about a 0.02 millimeter gap between the bearing cap  50  and camshaft journal  46 , allowing for a thin film of oil in the gap. The camshaft journals  46  contain oil upon their outer surface due to oil leaking from the bearing caps  50 .  
         [0039]     Details of the prior art bearing cap  50  are further illustrated in  FIGS. 5 and 6 . Each bearing cap  50  is made up of two end portions  52  and a central portion  54 . Each of the end portions  52  has a bore  56  therethrough and a locating dowel (not shown) protruding from one end of the bore  56 . The protruding portion of the locating dowels (not shown) fit into corresponding bores (not shown) in the engine on either side of the camshaft journal  46 , where fasteners  59  can be inserted to install and maintain the bearing caps  50  in place. When installed, a semi-circular bearing surface  60  within the central portion  54  of the bearing caps  50  is approximately 0.02 millimeters from surface contact with the camshaft journal  46  as described above.  
         [0040]     The side surfaces  62  of the central portion of bearing cap  50  are generally flat and normal to the direction of rotation of the camshaft  36 . Protruding from each side of the central portion  54  of the bearing caps  50  are oil diverter pads  64 . Prior art indications are that the oil diverter pads  64  preferably extend to and form a part of the semi-circular bearing surface  60  and, alternatively, that the oil diverter pads  64  can be recessed slightly from the bearing surface  60 , so long as this additional gap formed is minimal, allowing oil to still be diverted by the pads  64 . The oil diverter pads  64  are preferably but not necessarily formed integrally with the camshaft bearing caps  50  for ease of manufacture.  
         [0041]     In prior art teachings, the width (i.e., the distance from point a to point b, shown in  FIG. 6 ) of a pad  64  has only a small effect upon the flow of oil from camshaft journal  46 . Therefore, the width can be determined based upon ease of fabrication and assembly so long as it is wide enough to withstand the forces encountered in operation. A width between 3 and 12 millimeters appears preferable.  
         [0042]     Additionally, the prior art indicates a thickness (i.e., the distance from point b to point c, shown in  FIG. 6 ) of a pad  64  can also vary and, in general, that the thicker the pad  64 , the quicker the oil will be diverted from the surface of the camshaft journal  46  to the cam lobes  34 . The minimum thickness is preferably greater than 1 millimeter; and the maximum thickness is a tradeoff of manufacturing considerations, including fabrication and the space available for the pad  64  to protrude without interfering with the operation of the cam lobes  34  and  35 , while still minimizing the time to divert the oil. The preferred thickness indicated is between 1 and 3 millimeters.  
         [0043]     Application of the prior art in a 90 degree V-type engine shown in  FIGS. 13 and 14  has demonstrated that the centrally located oil diverter pad  64  does not adequately divert oil  66  substantially away from the camshaft cap  50  to the adjacent camshaft lobe  34 . The flow (addressed by Arrow D) of oil  66  flows around the oil diverter  64  and never leaves the side surface  62  of the camshaft cap  50 . This phenomenon occurred regardless of the direction of rotation as shown by Arrow E.  
         [0044]     An exaggerated version of prior art was made as a prototype camshaft cap  50  with a 7 mm thickness (distance between points b and c) as shown in  FIGS. 7 and 8 . The prototype camshaft cap  50  was in accordance with prior art with the exception of the thickness of the oil diverter pad  64 . The centrally located oil diverter pads  64  were effective in directing oil  66  to the adjacent camshaft lobes  34  when the camshaft  36  was rotated in a direction E counter to what is illustrated in  FIGS. 15 and 16 . However, when the camshaft  36  is rotated in direction E, while oil  66  flows from the side surface  62  of the camshaft cap  50  (shown by D) and is diverted by the oil diverter pad  64  not to the camshaft lobe  34 , but back toward the side surface  62  of the camshaft cap  50  and down the camshaft tower  67 .  
         [0045]     The foregoing description of known prior art embodiments and teaching indicates the inadequacy of adequate lubricating capabilities of the known configurations.  
         [0046]     In accordance with the invention, it has been discovered that the relocations (reorientation of oil diverter pads results in a more efficient and broader distribution of the lubricating oil function.  
         [0047]     In the description of the invention as depicted in  FIGS. 3, 4 ,  9 - 12 , and  17 - 24 , reference numbers followed by the lower case (“i”), unless otherwise indicated, function essentially as described to the same numbers (without “i”) applied, as described hereinabove to the prior art figures of the drawing.  
         [0048]     The invention as seen by reference to  FIGS. 3, 4 ,  7 - 12  and  17 - 24  and as illustrated more particularly by reference to  FIGS. 9 and 10  involves a relocation of the oil diverter pads  64  from the central portion  54  of the camshaft cap  50  towards one end  52  of the camshaft cap  50  such that the oil diverter  64  is in a vertical position when the camshaft cap  50  is installed on the engine  20  as shown in  FIGS. 3, 4  and  9 . I have discovered that with the oil diverter pad  64  in this position, oil  66  is diverted along a path (as shown by D) away from the camshaft cap  50  toward the adjacent camshaft lobe  34  where it is needed when the camshaft  36  rotates in a direction E.  FIGS. 21 and 22  illustrate the relationship of the direction of camshaft  36  rotation E for the other cylinder bank of a V-type engine. The invention has been found to surprisingly and effectively divert the oil  66  along a path D from the camshaft cap  50  toward the camshaft lobe  34  when the camshaft  36  rotates in the opposite direction E as compared to  FIGS. 17 and 18 .  
         [0049]     As an alternative and further advantage the revised configuration of the invention is amenable to a “casting-friendly” design as shown in  FIGS. 11 and 12 , so that the camshaft cap  50  can divert the oil  66  away from the camshaft cap  50  toward the camshaft lobe  34  when the camshaft  36  rotates in either direction E. This is illustrated in  FIGS. 19, 20 ,  23 , and  24 . What is unique to the “casting-friendly” design characterization is that there are multiple planes that can be used to divide a top portion and a bottom portion of the camshaft cap. Any one of these planes is capable of representing an interface plane between an upper and lower casting die from which the basic camshaft cap shape can be cast. This design development facilitates and eases mass production of cast camshaft caps.  
         [0050]     While the best mode for carrying out the invention has been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.