Internal-combustion engines – Poppet valve operating mechanism – Tappet
Reexamination Certificate
1998-12-01
2001-04-03
Lo, Weilun (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
Tappet
C123S090350
Reexamination Certificate
active
06209498
ABSTRACT:
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.
REFERENCES:
patent: 3314303 (1967-04-01), Maat
patent: 4708102 (1987-11-01), Schmid
patent: 4741298 (1988-05-01), Rhoads
patent: 4747376 (1988-05-01), Speil et al.
patent: 4809651 (1989-03-01), Gerchow et al.
patent: 5022356 (1991-06-01), Morel, Jr. et al.
patent: 5127374 (1992-07-01), Morel, Jr. et al.
patent: 5186130 (1993-02-01), Melchior
patent: 5188068 (1993-02-01), Gaterman, III et al.
patent: 5566652 (1996-10-01), Deppe
patent: 5673661 (1997-10-01), Jesel
patent: 5806475 (1998-09-01), Hausknecht
Banner & Witcoff , Ltd.
Competition Cams, Inc.
Lo Weilun
LandOfFree
Roller valve lifter with oiling channel does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Roller valve lifter with oiling channel, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Roller valve lifter with oiling channel will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2533204