Breather assembly for an internal combustion engine

Details Breather assembly for an internal combustion engine Breather assembly for an internal combustion engine

1999-11-23

2001-07-24

Denion, Thomas (Department: 3748)

Internal-combustion engines

Poppet valve operating mechanism

Rocker

C123S572000, C123S573000

Reexamination Certificate

active

06263847

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to rocker support assemblies and breather assemblies for internal combustion engines.
BACKGROUND
Combustion gases produced in the combustion chamber of an internal combustion engine are commonly forced under pressure to flow past the piston of the engine and into the engine's crankcase. Such gas is called “blow-by” gas, and usually consists at least partially of an air/oil mist. The reciprocation of the piston typically causes pressure fluctuations in the crankcase, causing the air/oil mist in the crankcase to be routed through an air cleaner having an air filter and back to the intake of the carburetor. It is undesirable to have oil in the combustion chamber because this leads to accumulations of oil in the valves and combustion chamber which may interfere with the operation of the engine. Also, the air filter in the air cleaner must be replaced frequently due to larger amounts of oil suspended in the air passing through the air cleaner, adding maintenance expense.
To alleviate this problem, it is customary in a four cycle engine to provide a breather system for separating the oil from the air/oil mist prior to recycling the air through the air cleaner and the carburetor. In a typical breather system as shown in U.S. Pat. No. 4,169,432, the oil mist in the crankcase is subjected to positive pressure when the piston travels in a downstroke, and the oil mist is forced through a breather passage containing a check or breather valve to an oil separation chamber where the oil mist is separated from the gas. On the upstroke of the piston, the pressure in the crankcase changes from positive to negative and the separated oil is drawn back into the crankcase through a return passage.
SUMMARY
The present invention provides a rocker support assembly for an internal combustion engine of a motor vehicle (e.g., a motorcycle). The rocker support assembly includes a pair of rockers and a breather assembly including a breather housing that is advantageously positioned between the rockers. Such positioning of the breather housing provides a compact, low profile rocker box. Furthermore, by properly positioning the rockers, the breather housing can be positioned in the middle of the rocker box to enhance the efficiency of the breather system.
In one embodiment, the housing at least partially defines an inlet aperture, an outlet aperture, and a passage in fluid communication between the inlet aperture and the outlet aperture. A pressure-responsive member is positioned in the housing and is operable in response to pressure differences in the passage to permit or inhibit fluid flow through the passage from the inlet to the outlet. A filter element can also be disposed within the housing such that substantially all fluid flowing from the inlet aperture to the outlet aperture passes through the filter element.
Other principal features and advantages of the invention will become apparent to those skilled in the art upon review of the following drawings, the detailed description and the appended claims.


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Harley-Davidson Motor Company Service Manual, XLH Models. 1993 and 1994 Official Factory Manual, pp. 3-13 and 3-40.
1340 Models 1993 and 1994 Parts Catalog—p. 6 undated.

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