Internal-combustion engines – Lubricators – Crankcase – pressure control
Reexamination Certificate
2000-02-16
2001-05-15
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Lubricators
Crankcase, pressure control
C184S006130
Reexamination Certificate
active
06230680
ABSTRACT:
This invention relates to lubrication systems for four-stroke cycle motorcycle engines, and particularly to lubrication systems not relying only on wet sump splash or drip lubrication to supply lubricating oil to crankshaft main bearings and connecting rod bearings.
RELATED ART
Conventional motorcycle engines have employed splash lubrication of “wet sump” oil collected in the crankcase to lubricate main bearings and connecting rod bearings on the crankshaft. When starting cold, this oil exhibited high viscosity, making the engine hard to start.
Moreover, such conventional engines customarily incorporated two inexpensive check valves for controlling the flow of oil, with inadequate results. These check valves normally incorporate roughly fabricated seats, which may have rough spots or burrs preventing reliable check valve seating. A first check valve receiving oil pump output is nominally set to open at about 3 psi, but inadequate seating allows it to leak oil constantly to the tappets or valve guides and the cylinder walls. Faulty operation of the first check valve often prevents a second plunger type check valve from reaching its nominal opening pressure of about 40 psi, thus preventing adequate lubricating oil from reaching the crankshaft bearings. The connecting rod crankshaft bearings are generally roller bearings, to carry maximum loads, and inadequate or intermittent lubrication often causes premature failure of these bearings.
BRIEF SUMMARY OF THE INVENTION
The present invention employs three high precision ball check valves, fabricated of stainless steel with smoothly honed check valve seats. High precision check valve springs permit precise control of valve opening pressures and assure adequate lubrication even when the engine is idling.
Accordingly, a principal object of the invention is to provide reliable lubrication of the motorcycle engine at all engine speeds, producing low friction operation, successful scavenging of lubricated surfaces and satisfactory cooling.
Another object is to provide a steady stream of oil at 8 to 12 psi to the crankshaft bearings, regardless of engine speed.
Oil supplied to the crankpin and connecting rods also supplies oil to the pistons and cylinders, drastically reducing cylinder temperatures, and still another object is to assure that such cooling is reliably achieved.
Other objects of the invention will in part be obvious and will in part appear hereinafter.
The invention accordingly comprises the features of construction, combinations of elements, and arrangements of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.
REFERENCES:
patent: 2263414 (1941-11-01), Beneshek et al.
patent: 2453217 (1948-11-01), Gregg et al.
patent: 2458763 (1949-01-01), Birmann
patent: 5937817 (1999-08-01), Schanz et al.
Webster and Putnam, Motorcycle Operation and Service, 1986, pp. 177-187.
Johns, Edmundson, Scharff, Motorcycles, Fundamentals, Service and Repair, 3rd ed. 1999, pp. 234-242.
Motorcycle Mechanics Institute, The Complete Guide to Motorcycle Mechanics, 2nd ed., 1994, pp. 28-35; 42-43; 134-136.
Kamen Noah P.
Ware Fressola Van Der Sluys & Adolphson LLP
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