Internal-combustion engines – Charge forming device – Crankcase vapor used with combustible mixture
Reexamination Certificate
2000-06-08
2001-10-09
McMahon, Marguerite (Department: 3747)
Internal-combustion engines
Charge forming device
Crankcase vapor used with combustible mixture
Reexamination Certificate
active
06298836
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention concerns an arrangement to extract air from a crankcase of an internal combustion engine of the substantially throttless type.
2. Description of Related Art
There are various known arrangements for extracting air from engine crankcases. German Utility Model 18 31 027 describes, for example, such an arrangement having an air conduit extending from the crankcase to an intake fitting formed to the engine air filter assembly. This arrangement achieves a relatively high negative pressure in the conduit relative to the crankcase which results in desired air extraction therefrom.
Likewise, German DE-B 14 76 052 describes an air extracting arrangement for a crankcase of an internal combustion engine having a carburetor. A filter cap allows air to enter the crankcase and an extraction line withdraws air therefrom to the narrowest position of the carburetor's venturi. A control mechanism is used to regulate air flow.
Further, in the extracting arrangement for air disclosed in German DE 37 26 332 C1, a crankcase extraction line is connected to a throttle housing and specifically to a trough-like depression formed therein. This construction allows condensation which may form particularly during idling of the engine to collect in this depression rather than on the throttle itself.
In the carburetor or manifold-injection fitted type of internal combustion engines described above, a difference in pressure between the throttle and crankcase regions is utilised in order to purge crankcase air. Typically, an outlet fitting on the cylinder head valve cover is utilised as an exit for air withdrawn from the engine. The extracted air includes so-called blow-by gases (about the pistons and piston rings). It is desirable to remove these blow-by gases because they are abrasive and promote engine wear of pistons and cylinders.
SUMMARY OF THE INVENTION
In a substantially throttle-free internal combustion engines, e.g. a direct-injection spark-ignition internal combustion engine, the aforedescribed arrangements for extracting air from the crankcase are not possible because the differential pressure which is sued cannot be generated without a throttle.
The object of the present invention is to provide an arrangement for extracting air and blow-by gases from the crankcase of a substantially throttless internal combustion engine, in particular a direct-injection spark-ignition internal combustion engine, during all operating states of the engine.
The arrangement according to this invention produces a depressed air pressure in the engine's air intake line which is used to reliably extract crankcase air and blowby gas from the engine crankcase.
The aforementioned negative-pressure producing arrangement may be in the form of a venturi nozzle section of the engine air intake system. Such a venturi nozzle has the advantage that it does not influence the quantity of air to the internal combustion engine and as a result of this the engine maintains its full power capacity.
Further advantageous configurations and developments of the invention can be understood from a reading of the following detailed description of and embodiment of the invention, reference being to the drawing of the embodiment.
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Bach Klaus J.
Daimler-Chrysler A.G.
MacLean Kenneth H.
McMahon Marguerite
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