Internal-combustion engines – Lubricators – Crankcase – pressure control
Reexamination Certificate
2000-09-15
2001-07-17
McMahon, Marguerite (Department: 3747)
Internal-combustion engines
Lubricators
Crankcase, pressure control
Reexamination Certificate
active
06260534
ABSTRACT:
The invention relates to an oil-pickup system for an internal combustion engine according to the preamble of claim
1
.
An important criterion for the maximum permissible inclination during operation of internal combustion engines is the lubricating-oil system. If the inclination of the internal combustion engine exceeds a critical value, it is important to prevent the oil pump from sucking in air and the propulsion-unit components disposed at the bottom of the crankcase from churning in the oil, which would lead to heating of the lubricating oil and would also hinder the return flow of oil, for example from the valve-lifter housing to the oil pan. Finally, at steep inclinations, oil can travel through the crankcase vents into the combustion-air intake system, which in the extreme case could cause engine damage in diesel engines because of a speed increase that can no longer be controlled.
Extreme inclinations of internal combustion engines occur, for example, when they are used for motor-vehicle drives. In this area attempts have been made to avoid the problems mentioned hereinabove by lowering the oil level by means of a deeper oil pan. It was indeed possible largely to avoid the cited disadvantages by particularly deep oil pans. Such special oil pans, however, cause high manufacturing costs and limit the use of the engine because of its greater space requirement.
In a known oil-pickup system (German Laid-open Application DE-OS 2339730) of the type mentioned in the introduction, the control valves are disposed at the inside ends of the respective oil-pickup tubes, or in other words close to the center of the oil pan. The danger therefore exists that the control valves will respond only after a delay, and so intake of residual air flows has to be tolerated.
The object of the present invention is therefore to provide an oil-pickup system which avoids the foregoing disadvantages and which in particular responds sufficiently sensitively to avoid intake of air reliably even at steep inclinations.
This object is achieved by an oil-pickup system with the features of claim
1
. Advantageous embodiments are described in the dependent claims.
According to the invention, the oil-pickup system is provided with at least three oil-pickup tubes having at least four pickup heads, which are in communication with the oil pump via a suction tube and which are disposed in the oil pan in such a way that, when the internal combustion engine is in inclined position, intake of air is prevented by control valves disposed in the oil-pickup tubes. Those control valves are open during “normal” horizontal position of the oil pan. At extreme inclination of the oil pan, however, only the control valves wetted with oil are open. All other control valves remain closed. The oil-pickup system according to the present invention can be easily retrofitted to existing internal combustion engines, since it is merely necessary to detach the oil pan and the normal suction strainer and replace the latter by the oil-pickup system according to the present invention. Adjustment of the control valves can be accomplished mechanically or by other suitable means.
By the fact that the control valves in the present invention are provided with valve plates disposed to slide along slide rods under the effect of gravity and with valve seats disposed at the tube ends, there is achieved simple but nevertheless sensitively responding mechanical gravity control of the valves. In addition to the desired automatic open and closed positions of the control valves, depending on inclination, this gravity control also has a “fail-safe” function, since simultaneous closing of all valves is reliably prevented by the fact that two valve plates are disposed on a common slide rod.
One advantageous embodiment of the invention provides that three oil-pickup tubes are disposed in the form of an “H”, each of the two side tubes being provided with two pickup heads. This arrangement ensures that sufficient oil to ensure pickup of oil without air is present in at least one corner of the oil pan, regardless of tilt position. The suction tube can be disposed centrally, for example, between the two side tubes, by means of a flange to the connecting tube.
Further advantageous embodiments of the inventive oil-pickup system can be formed by arranging the oil-pickup tubes in the form of an “X”, “Z” or rectangle. What is important in each case is that at least one pickup head be present at all corners of the oil pan where the oil level can collect during inclined positions. Depending on the geometry of the oil pan, this may also be possible, for example, by a triangular, polygonal or star-shaped arrangement of oil-pickup tubes.
A further advantageous embodiment of the present invention provides that the pickup heads are provided with a pickup opening directed toward the pan bottom. Without such a structural geometry, a minimum oil level corresponding to the size of the tube diameter would have to be present to avoid intake of air. An even lower oil level is possible only with the oil-pickup openings disposed at the bottom, as in the advantageous embodiment.
In yet another advantageous embodiment, filter screens are disposed on the pickup heads. Hereby intake of impurities present in the oil sump is prevented.
A final advantageous embodiment provides that a nonreturn valve is disposed at the junction between suction tube and oil-pump seat, in order to prevent the suction-tube and pump spaces from running empty when the engine is stopped.
A practical example of the present invention will be described hereinafter with reference to the attached drawings, wherein:
FIG. 1
shows a schematic top view of an oil-pickup system according to the present invention in section;
FIG. 2
shows a schematic side view from direction A—A in
FIG. 1
in section, the oil pan being in horizontal position, and
FIG. 3
shows a view according to
FIG. 2
, but with the oil pan tilted.
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Kampichler Guenter
Madl Albert
Helfgott & Karas P.C.
McMahon Marguerite
Motorenfabrik Hatz GmbH & Co. KG
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