Internal-combustion engines – Charge forming device – Crankcase vapor used with combustible mixture
Reexamination Certificate
2000-01-28
2001-03-13
McMahon, Marguerite (Department: 3747)
Internal-combustion engines
Charge forming device
Crankcase vapor used with combustible mixture
C123S573000
Reexamination Certificate
active
06199543
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an oil deflector apparatus (a baffle) for use in apparatus for cleaning internal combustion engine crankcase breather (blow-by) gas, an internal combustion engine including such apparatus, and a method of use of such apparatus.
During the compression and power strokes in an internal combustion engine, the difference in gas pressures above and below a piston is sufficient to cause leakage (blow-by) of gas past the piston into the engine crankcase. The resulting increase in pressure within the crankcase can force oil past by the engine oil seals and this pressure may also damage the seals and hence lead to further leakage of oil.
To diminish the damaging effects of blow-by it is normal to relieve the crankcase pressure either by venting the breather gas to atmosphere via an open breather or by connecting the crankcase to the engine air intake system whereby breather gas is conveyed to the engine combustion chamber via the engine air inlet system and under the control of a pressure regulating means. This latter system constitutes a closed-circuit breather system.
It is desirable to include, in breather systems, means to retrieve oil contained in breather gas and return this to the engine lubricating oil system for re-use. Otherwise the carry-over of oil will lead to pollution and, in a closed-circuit system, to fouling of turbocharger compressor vanes, engine poppet valves and other components in contact with inlet air.
As well as leading to contamination and emission problems, the carry-over of oil in breather gas will reduce the volume of oil available for the lubricating and cooling requirements of the engine. It is desirable to minimised oil carry-over, and an oil/air separator is therefore included in most closed-circuit breather systems.
A further problem with oil carry-over in the closed-circuit breather system of an engine, especially of the diesel type, is that the oil can fuel the engine and lead to an unintentional and possibly severe increase in engine speed known as ‘run-away’.
The run-away problem may be exacerbated where the engine is operated at high gradients (angles of inclination), especially where conditions of abuse prevail, and in particular where the designed maximum oil level in the sump has been exceeded, where the intake air filter is dirty and/or where blow-by levels are high due to engine wear. A particular problem may arise in severe abuse conditions, at severe inclinations, in that the surface of the volume of oil within an engine sump can become closer to the breather gas connection. The tendency of this volume of oil to simultaneously become agitated, by for example the partly submerged and rotating crankshaft, can result in oil being splashed and sucked up into a breather inlet and hence translocated to the breather separator. This can be a particular problem in situations where, as might be desirable for other reasons, the breather gas inlet is already located in a relatively lower position within the engine, for instance in the engine crankcase.
Under these abuse conditions, even where a conventional separator is provided the breather system may take up more oil than the separator can handle and oil can be drawn into the engine air intake system and hence to the combustion chamber where it can fuel the engine and lead to run-away.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a baffle means for fitment to a breather gas inlet of an apparatus for cleaning internal combustion engine breather which limits the ingress of oil into the breather gas apparatus, in particular for engines operating at high gradients.
It is further object of the present invention to provide an apparatus for separating oil from breather gas in an internal combustion engine, in particular an engine operating at high gradients.
It is a further object of the present invention to provide a method of separating oil from breather gas in an internal combustion engine in particular an engine operating at high gradients.
According to a first aspect of the present invention an oil deflector apparatus (baffle) for fitment over breather gas inlet means of an internal combustion engine breather system to limit the ingress of oil droplets comprises:
a baffle plate disposed at a first end, a second end connectable to a breather gas inlet means, and a gas conduit extending between said ends being open at the second end and closed at the first end by the baffle plate and having a perforated wall.
The gas conduit has divergent walls such that the cross-sectional area of the conduit increases as the conduit extends from said second end towards said first end.
The baffle plate may be generally planar, and disposed to lie in use in an orientation generally perpendicular to the breather gas flow into the inlet. The plate may be of such a size as to extend outwardly beyond the perimeter of the conduit at the second end. The plate may have a D-shaped face.
The baffle is particularly effective in limiting the amount of oil splash sucked into breather gas inlet means located lower in the engine, for example within the crank case portion.
Although a simple perforated baffle is effective in reducing the likelihood of oil droplets being sucked into the breather inlet, particularly if in suitable orientation, the configuration and orientation of the baffle components is of importance in optimising effectiveness.
Preferably the baffle comprises a plurality of perforated baffle elements extending between the first and second ends so as to be disposed around a breather gas flow into the inlet in use.
Preferably the baffle elements comprise a plurality of substantially planar perforated baffle faces formed into a conduit by means of perforated or un-perforated intermediate portions. In a preferred arrangement, the baffle is provided with three such baffle faces, so as to produce a baffle conduit having substantially triangular cross-section.
According to a further aspect of the present invention, a breather system for an internal combustion engine comprising breather gas inlet means to receive breather gas from within an engine casing, and fluidly connected via breather gas conduit means to a separator capable of separating oil from suspension within the breather gas, has baffle means as above described fitted in position over the breather gas inlet means to limit the ingress of oil droplets.
Preferably, the breather gas inlet means are disposed to open away from the vertical, for example generally horizontally, with respect to an engine in a nominally horizontal orientation. Where the breather gas inlet means are so arranged, a baffle in which the baffle elements comprise a plurality of substantially planar baffle faces formed into a conduit by means of intermediate portions as above described is particularly preferred.
In such an arrangement, the intermediate portions comprise areas of relatively high curvature, or even sharp corners. The baffle is particularly effective where the breather arrangement is such that the breather gas inlet means open nominally horizontally into the volume defined by an engine casing when the engine is in a nominally horizontal disposition, and the baffle is arranged to be fitted onto the breather gas inlet means to be so disposed that an intermediate portion is nominally lowermost with the engine in such an horizontal orientation. Most preferably, a baffle comprising three baffle faces and having substantially triangular cross-section, as above described, is fitted to the inlet means and is so disposed that a baffle face is nominally uppermost in use with the engine in a nominally horizontal orientation. In this orientation, the holes in the baffle are presented at an angle to the prevailing direction of oil droplets impinging on the baffle.
A particular advantage of the use of the baffle in accordance with the present invention is that it permits consideration of use of breather inlets located in lower positions on the engine within the crank case volume, rather than wit
Hickman Alan J.
McMahon Marguerite
Perkins Engines Company Limited
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