Internal-combustion engines – Lubricators – Crankcase – pressure control
Reexamination Certificate
1999-09-16
2001-07-10
Wolfe, Willis R. (Department: 3747)
Internal-combustion engines
Lubricators
Crankcase, pressure control
Reexamination Certificate
active
06257193
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to hydraulic systems for engines. More particularly, the present invention relates to internal combustion engines having a pick-up tube in the oil pan for pumping oil from the oil reservoir outside the crankcase to the oil pump inlet.
BACKGROUND OF THE INVENTION
New vehicle designs and additional accessories require an engine to deliver more horsepower. However, the engine needs a larger crankshaft to provide the additional horsepower. A larger crankshaft requires larger main bearing caps for stabilization. To operate the engine properly, the larger crankshaft and bearing caps must be placed lower in the crankcase. This placement eliminates the previously available space for the oil pump inlet tube.
In a typical engine configuration, an oil pump connects to an inlet tube outside the crankcase. The inlet tube connects to the pick-up tube inside the crankcase or inside the oil pan. The pick-up tube is positioned in the oil pan for pumping oil from the oil reservoir formed by the oil pan. When the engine is operating, oil is pumped from the oil reservoir, through the pick-up tube, through the inlet tube, and into the oil pump.
When the inlet tube is moved outside the crankcase, there are more opportunities for leaks to develop. Leaks also may develop from improperly connected pick-up and inlet tubes. Leaks may develop because the oil pan extends beyond the crankcase. Leaks also may develop because the oil pump inlet tube or the pick-up tube extends through a passage formed in the oil pan. In the later two cases, a gap may form along an edge of the oil pan. This scenario is especially true when the oil pan extends to connect to the engine'front cover. In assembly operations, it is extremely difficult to consistently match the edges of the front cover and crankcase from engine to engine. If the edges of the front cover and the crankcase are uneven, a gap will form when the oil pan is attached.
Leaks also are a greater concern when the oil pump inlet tube is moved outside the crankcase. While no leak is desirable, a leak inside the crankcase at the connection of the inlet and pick-up tubes is less consequential. Such a leak would cause oil to leak into the inlet tube or into the crankcase or oil pan. These leaks would have less impact because the crankcase and oil pan are full of oil during engine operation.
In contrast, a leak outside the crankcase would have an adverse impact on engine performance. Such a leak may cause oil to escape from the engine. While it may not cause an immediate problem, it would harm the engine over the long term. Moreover, a leak may cause air to enter the hydraulic system. Air in the hydraulic system would have a catastrophic impact on engine operation.
To avoid some of these leaks, the pick-up tube and the oil pump inlet tube could be one piece. However, they typically are not one piece because of manufacturing costs. The one piece would stick out of the oil pan or the crankcase. This arrangement has a greater chance of being damaged during transportation of the part and assembly of the engine. The combined tube may be hit and may even snap when the part is shipped or the engine moves through the assembly line. Moreover, a combined tube would not prevent leaks from gaps in the oil pan connections.
Accordingly, there is a need for a direct passage from the oil reservoir to the oil pump in an engine that does not pass through the crankcase.
SUMMARY OF THE INVENTION
The present invention provides an engine oil pan with a direct passage from the oil reservoir to the oil pump. A direct passage is one that does not pass through the crankcase. An engine crankcase connects to a front cover having a front half and a back half. The front half forms an inlet path to the oil pump, thus avoiding the need for an oil pump inlet tube. An oil pan connects to the crankcase and the front cover. There may be a gap between the oil pan and the front cover.
The oil pan has a pick-up tube disposed along an oil pan housing, which forms an oil reservoir. The pick-up tube is positioned to take oil from the deeper part of the oil reservoir. The pick-up tube connects the oil reservoir to the inlet path formed in the front half of the front cover.
Preferably, a nipple is connected by interference bonding to the pick-up tube. The nipple also is connected to the front cover by being inserted into the inlet path. The nipple may have a tapered end. The front half may have a tapered portion for receiving the nipple. The tapered end and the tapered portion may have the same taper to make a more secured connection.
An O-ring or a gasket is disposed adjacent to the nipple and between the pick-up tube and the front half. The pick-up tube and the front half each may have a groove for positioning the O-ring. Preferably, the O-ring is wider than the gap between the front cover and the oil pan. When the O-ring is not wider than the gap, the O-ring may be positioned adjacent to the contact point between the nipple and the front cover.
An alternate embodiment omits the nipple. A gasket is disposed between the oil pan and the front cover. Preferably, the gasket is disposed in grooves formed in the oil pan and the front cover.
The following drawings and description set forth additional advantages and benefits of the invention. More advantages and benefits are obvious from the description and may be learned by practice of the invention.
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Alpan Karen A.
Bergman David G.
Rowland David L.
Ali Hyder
Calfa Jeffrey P.
Hernandez Gilberto
International Truck and Engine Corporation
Sullivan Dennis Kelly
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