Patent Publication Number: US-6209498-B1

Title: Roller valve lifter with oiling channel

Description:
FIELD OF THE INVENTION 
     The present invention relates to a roller valve lifter having a roller at one end thereof that cooperates with the cams of a camshaft in an internal combustion engine. More specifically, the invention relates to a valve lifter having an oiling channel to improve oil flow to the roller, roller bearing and the cam of a camshaft. 
     BACKGROUND OF THE INVENTION 
     Internal combustion engines utilize valve lifters that operate in conjunction with cams of a camshaft to reciprocate the lifters. Typically, as the camshaft rotates, the cams of the camshaft operatively engage an end of the valve lifter to reciprocate the valve lifters in an internal combustion engine. The valve lifters are located within cylindrical bores in an engine block. The engine block provides a travel passageway for each valve lifter and allows oil to lubricate each lifter assembly. Oil is directed to the valve bores by a straight and common transverse oil passageway that intersects the valve bores. 
     Various valve lifter designs have been developed for specific engine environments. Hydraulic valve lifter assemblies and solid lifters are typically used for engines having relatively low revolutions per minute. Rolier valve lifters, which utilize a roller to contact the cams of a camshaft, are typically used in engines having relatively high revolutions per minute. The use of a roller to contact the cams reduces wear and extends the useful life of both the valve lifter and the cams of the camshaft. 
     One problem associated with valve lifters is the need to provide oil to the lifters as they reciprocate within the valve bores and to the valve lifter rollers and cams of the camshaft as the lifters ride on the cams. When using roller valve lifters, it is important to provide sufficient oiling of the rollers and cams particularly at the point of contact. A known approach to increase the oiling of these areas is to provide an oil pressure feed groove on the valve lifter. This oil pressure feed groove is typically an annular groove on the circumference of the tappet body of the valve lifter. Oil enters the oil pressure feed groove from the common transverse oil passageway in the engine block that intersects the valve bores. As the valve lifter reciprocates within the engine, the oil pressure feed groove carries oil up and down the valve lifter bore and also directs oil towards the roller of the valve lifter that engages the cam. Although this method serves to provide some quantity of oil to the rollers and cams, in an engine having high revolutions per minute, there is a need to maximize the quantity of oil flowing to the rollers and cams to decrease roller and cam wear. 
     Another problem associated with engines having high revolutions per minute and using roller valve lifters is the need to supply adequate oil to the roller bearings of the valve lifter. Inadequate oiling of the roller bearing results in excessive wear and may lead to catastrophic failure of the bearing, and consequently failure of the entire engine. A known approach to oiling the roller bearings is to provide an oil feed slot or slots in the portion of the valve lifter that houses the roller. This oil feed slot directs any oil at the distal end of the valve lifter towards the shaft and bearings of the roller. While this method attempts to provide oil to the roller bearing, oil may not be present in this area or may be directed away from the shaft and bearing due to the rotation of the cam. Thus, there is a need to provide a positive flow of oil to the roller bearings to ensure oiling of the roller bearings. 
     SUMMARY OF THE INVENTION 
     In accordance with a preferred embodiment of the present invention, a valve lifter assembly for use in internal combustion engines having improved oiling characteristics is provided. The invention preferably includes a cylindrical tappet body having a forked housing for receiving a cylindrical roller, wherein the cylindrical roller includes a bearing assembly and a circular opening for positioning about a shaft located in the forked housing. The tappet body further includes an oil pressure feed groove and oil feed slots located on inner planar surfaces of the forked housing. The invention further preferably includes an oiling channel located on an external surface of the tappet body to direct oil to the cylindrical roller and roller bearing assembly of the valve lifter. 
     The tappet body preferably includes a cylindrical bore extending from a first end along the longitudinal axis of the tappet body for receiving a rod to operatively connect the tappet body to a valve member. A second end of the tappet body preferably has a forked housing for receiving a cylindrical roller. The cylindrical roller preferably includes a bearing assembly consisting of bearing members and an inner race. The inner race contains a circular opening for receiving a shaft located in the forked housing. The shaft is connected to both sides of the forked housing on the tappet body, and the cylindrical roller is rotatably mounted to the shaft. 
     The valve lifter also preferably includes an oil pressure feed groove comprising an annular groove on the circumference of the tappet body of the valve lifter for receiving oil as the valve lifter reciprocates in the cylindrical bore of an engine block. The tappet body may also include oiling holes to provide oil to the rod member located in the cylindrical bore of the tappet body. 
     The first and second sides of the forked housing on the tappet body preferably have oil feed slots on an inner planar surface of each side. The tappet body further includes an oiling channel located on an external surface of the tappet body preferably extending from the oil pressure feed groove to the forked housing. 
     Therefore, the present invention facilitates the movement of oil to the cylindrical roller and the bearing of the roller. Features of the subject invention which provide the oiling properties include an oil pressure feed groove, oil feed slots and an oiling channel on the tappet body. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further advantages of an illustrative embodiment of the present invention will be more readily apparent from the following detailed description which proceeds with references to the accompany drawings. 
     FIG. 1 is a side view of an embodiment of the valve lifter of the present invention. 
     FIG. 2 is a bottom view of the second end of the tappet body having a forked housing and cylindrical roller. 
     FIG. 3 is a side view of the cylindrical roller. 
    
    
     While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawings and detailed description thereof are not intended to limit the invention to the particular from disclosed, but on the contrary, the invention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention. 
     DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT 
     The Valve Lifter 
     The present invention is directed to a valve lifter  10  for an internal combustion engine having a plurality of valve members  12  and having a camshaft  14  for causing reciprocating movement of the valve members  12 . 
     As shown in FIG. 1, the valve lifter  10  includes a cylindrical tappet body  16  having a first end  18  and a second end  20 . The tappet body is preferably made of high strength steel. First end  18  of the tappet body  16  contains a cylindrical bore  22  extending from the first end  18  of the tappet body  16 , along the longitudinal axis of the tappet body  16  toward the second end  20  for receiving the distal end of a rod structure  24  which is associated either with a rocker arm assembly (not shown), or with a bucket to directly engage the valve member  12 . 
     The second end  20  of the tappet body  16  includes a forked housing  26  having a first side  28  and a second side  30 . The forked housing  26  is adapted to receive a cylindrical roller  32 . The cylindrical roller  32  is rotatably mounted to the forked housing  26  by way of a shaft  34  connected to the first side  28  and the second side  30  of the forked housing  26 . As shown in FIG. 3, the cylindrical roller  32  further includes a bearing assembly  36  consisting of an inner race  38  and bearing members  40  for providing a wear means for the cylindrical roller  32  as it rotates on the shaft  34 . 
     In a preferred embodiment of the present invention, the second end  20  also contains a first oil feed slot  42  and a second oil feed slot  44 . As shown in FIG. 2, the first oil feed slot  42  is a depression located on the inner planar surface of the first side  28  of the forked housing  26 . Likewise, the second oil feed slot  44  is a depression located on the inner planar surface of the second side  30  of the forked housing  26 . Oil feed slots  42  and  44  preferably extend between second end  20  and shaft  34 . The oil teed slots  42  and  44  are also preferably 0.063 inches deep and 0.25 inches wide. 
     The valve lifter  10  may also contain an oil pressure feed groove  46  located on the valve tappet at body  16 . Preferably, the oil pressure feed groove  46  is an annular groove on the circumference of the tappet body  16  of the valve lifter  10  and is located between the first end  18  and the second end  20  of the tappet body  16 . Oil enters the oil pressure feed groove  46  from the common transverse oil passageway that intersects the valve bores  50 . As the valve lifter  10  reciprocates within the engine, the oil pressure feed groove  46  carries oil up and down the valve lifter bore  50  and also directs oil towards the roller  32  of the valve lifter  10  that engages the cam  54 . As known in the art, the valve lifter  10  may contain an oiling hole  48  located on the tappet body  16  between the first end  18  and the oil pressure feed groove  46 . The oiling hole  48  provides oil to the cylindrical bore  22  of the valve tappet body  16  and thus the rod  24 . 
     Oil Flow of the Valve Lifter 
     The valve lifter  10  is adapted to reciprocate in a bore  50  of an engine block  52  as illustrated in FIG.  1 . As mentioned above, the engine block  52  includes a number of valve bores, bore  50  being exemplary of the remaining bores. The engine block  52  contains a straight and common transverse oil passageway  51  that intersects the valve bore  50 . As the valve lifter  10  reciprocates in the valve bore  50 , the oil pressure feed groove  46  receives oil from the common transverse oil passageway  51  and traps the oil between the valve body  16  and the valve bore  50  to maintain oil between the valve lifter  10  and the valve bore  50 . The oiling hole  48  also receives oil from the reciprocating action of the valve lifter  10  in the valve bore  50 . 
     The second end  20  of the valve lifter  10  also receives oil through the reciprocating action of the valve lifter  10  in the valve bore  50 . Oil is provided to the second end  20  of the valve lifter  10  by the camshaft  14 . Camshaft  14  is located within the engine block  52  and preferably is covered in oil resulting from oil that bleeds past camshaft bearings and is slung by centrifugal force off of the camshaft  14 , as well as oil that bleeds past the lifters and down onto the camshaft  14 . As the camshaft  14  rotates within the engine block  52 , oil is carried on the individual cam  54  which contacts with the cylindrical roller  32  located in the second end  20  of the valve lifter  10 . As the cam  54  and cylindrical roller  32  engage, oil enters the first oil feed slot  42  and the second oil feed slot  44  located on the first side  28  and the second side  30  of the fork housing  26  of the valve lifter  10 , respectively. These oil feed slots  42  and  44  provide oil to the shaft  34  and bearing assembly  36  of the roller  32  which maintains the cylindrical roller  32  in the fork housing  26 . This oil serves to prevent wear of the bearing assembly  36  and to maintain adequate rotation of the cylindrical roller  32 . 
     Oiling Channel 
     In a preferred embodiment of the present invention, the valve lifter  10  incorporates an oiling channel  56 . The oiling channel  56  is positioned on the external periphery of the tappet body  16  and preferably extends from the inner planar surface of the first side  28  of the forked housing  26  to the oil pressure feed groove  46 . The oiling channel  56  may also be positioned at other locations in a generally longitudinal direction along the external periphery of the tappet body  16 . In a preferred embodiment the oiling channel  56  is 0.0313 inches wide and 0.0313 inches deep. However, it will be understood that an oiling channel of varying widths and depths may be provided within the scope of the present invention. The reciprocating motion of the valve lifter  10  in the bore  50  forces oil from the oil pressure feed groove  46  through the oiling channel  56  to the inner planar surface of the first side  28  of the forked housing  26 . Thus, the oiling channel  56  directs oil to the oil feed slots  42  and  44  which facilitates movement of pressurized oil to the bearing assembly  36  of the cylindrical roller  32 . 
     Operation 
     The rotation of the camshaft  14  facilitates the movement of oil to the bearing  36 . For example, as the camshaft  14  rotates in a clockwise direction, the cam  54  engages the cylindrical roller  32  causing the cylindrical roller  32  to rotate in a counterclockwise manner. Oil adhering to the surface of cam  54  is transferred to the surface of the cylindrical roller  32 . The counterclockwise rotation of the cylindrical roller  32  carries oil on the surface of the cylindrical roller  32  to the opposite side of the valve lifter  10  towards the oil pressure feed groove  46 . The oiling channel  56  on the opposite side of the valve lifter  10  further directs oil from the oil pressure feed groove  46  to first and second oil feed slots  42  and  44 . 
     The oiling channel  56  facilitates the movement of oil from the oil pressure feed groove  46  as the valve lifter  10  reciprocates in the cylindrical bore  50  of the engine block  52 . Furthermore, the oiling channel  56  redirects oil traveling on the surface of the cylindrical roller  32 . Once in the oiling channel  56 , oil can enter the first and second oil feed slots  42  and  44  and be directed to the bearing  36  of roller  32 . Oil at the bearing  36  provides lubrication of the bearing members  40 . 
     In view of the wide variety of embodiments to which the principles of the invention can be applied, it should be understood that the illustrated embodiments are exemplary only, and should not be taken as limiting the scope of the present invention. For example, more or fewer elements or components may be used in the figures. 
     The claims should not be read as limited to the described order or elements unless stated to that effect. In addition, use of the term “means” in any claim is intended to involve 35 U.S.C. §112, paragraph 6, and any claim without the word “means” is not so intended. Therefore, all embodiments that come within the scope and spirit of the following claims and equivalents thereto are claimed as the invention.