Internal-combustion engines – Charge forming device – Crankcase vapor used with combustible mixture
Reexamination Certificate
2001-10-25
2002-09-03
McMahon, Marguerite (Department: 3747)
Internal-combustion engines
Charge forming device
Crankcase vapor used with combustible mixture
Reexamination Certificate
active
06443136
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a breather apparatus provided with a gas-liquid separation chamber for separating oil contents from blow-by gases produced in an internal combustion engine.
2. Description of the Related Art
A gas-liquid separation chamber for separating oil contents from blow-by gases is usually provided on a blow-by gas returning device for retuning blow-by gases leaking from between the pistons and cylinder walls in an internal combustion engine to an intake system for combustion therein so that blow-by gases from which oil has been removed are then returned to the intake system so as to suppress the consumption of oil.
Shown in
FIGS. 7 and 8
is an example of an internal combustion engine
01
described in Japanese Utility Model Registration No. 2532890 in which a gas-liquid separation chamber of a type described above is provided within a cylinder head cover which covers a valve system from thereabove.
A valve train
05
is covered with a cylinder head cover
03
which is overlaid on a cylinder head
02
to be joined thereto.
A rectangular opening at a lower end of a side frame wall
04
which forms an upper space within the cylinder head cover
03
is closed with a bottom plate
06
so as to form a gas-liquid separation chamber
07
.
A blow-by gas outlet pipe
08
is provided in such a manner as to penetrate through the side frame wall
04
, and a blow-by gas inlet port
09
is opened in the bottom plate
06
along a corner portion which is situated away from the blow-by gas outlet port
08
.
Then, three bent portions
010
which are each bent to be inclined downwardly are provided at portions along a side edge of the circumferential edge portion of the rectangular bottom plate
06
where the blow-by gas outlet pipe
08
is situated, and a gap
011
through which oil is to be returned is formed in each bent portion
010
between a lower end face of the side frame wall
04
and the bent portion
010
.
Blow-by gases in the cylinder head cover
03
flow into the gas-liquid separation chamber
07
through the blow-by gas inlet port
09
, and the blow-by gases from which oil contents have been removed are then returned to the intake system through the blow-by gas outlet port
08
.
Oil separated from the blow-by gas and collected on an upper surface of the bottom plate
06
flows over the bottom plate
06
which is inclined along the inclination of the internal combustion engine toward the oil return gaps
011
, and oil so reaching the gaps flows out through the oil return gaps
011
into the lower space in which the valve train is accommodated.
The oil return gaps
011
are closed with oil which tries to flow out therethrough, so as to prevent blow-by gases present within the cylinder head cover
03
from being blown up into the gas-liquid separation chamber
07
through the oil return gaps
011
.
However, in the event that there is little oil flowing out through the oil return gap
011
, there may be a case where the gap is not closed with oil, and if this occurs, there may be a case where blow-by gases within the cylinder head cover
03
is blown up into the gas-liquid separation chamber
07
via the gaps
011
, resulting in a risk that oil separated from blow-by gases mixes again with the blow-by gases so blown up into the gas-liquid separation chamber to be sent into the intake system.
If the oil return gap
011
is narrowed, the gap
011
can easily be closed with oil, but there may be a case where the gap
011
is rigidly closed with oil due to its viscosity, resulting in a risk that oil is difficult to flow out through the gap
011
before a lot of oil is accumulated on the upper surface of the bottom plate
06
.
In addition, there is suggested (in JP-A-10-30423) an example in which an oil flow-down pipe is extended downwardly from a bottom plate constituting a gas-liquid separation chamber, and a lower end of the oil flow-down pipe is formed into an S-shape which faces laterally, whereby the oil flow-down pipe is closed with oil separated from blow-by gases to be collected in a bent portion of the S-shape which faces downwardly. However, this requires the special oil flow-down pipe and complicates the construction, where by the number of components is increased, resulting in a troublesome assembling process.
Additionally, with an oil flow-down pipe of a large diameter, oil does not flow out, and a large amount of oil is accumulated therein, whereas with an oil flow-down pipe of a small diameter, oil accumulated in the oil flow-down pipe is caused to flow back to be easily blown up into the gas-liquid separation chamber due to a negative pressure produced in the intake system.
The oil return gaps
011
are closed with oil which tries to flow out there through so as to prevent blow-by gases present within the cylinder head cover
03
from being blown up into the gas-liquid separation chamber
07
through the oil return gaps
001
.
Moreover, once blow-by gases have flowed into the gas-liquid separation chamber
07
through the blow-by gas inlet port
09
, a flow of the blow-by gases is formed as indicated by broken line arrows in
FIG. 8
which flow is directed over the gas-liquid separation chamber
07
toward the blow-by gas outlet pipe
08
.
Therefore, blow-by gases that have flowed into the gas-liquid separation chamber
07
through the blow-by gas inlet port
09
is allowed to act directly on oil accumulated in the oil return gap
011
due to the closure of the gap therewith, and oil is drawn into the blow-by gases to thereby be reversed.
This action makes it difficult for oil to flow out through the oil return gap
011
, and if there is only a small amount of oil that closes the gap, the small amount of oil is drawn into the blow-by gases, whereby the gap
011
cannot be closed, resulting in the fact that blow-by gases are easy to be blown up, reducing the gas-liquid separation effect.
SUMMARY OF THE INVENTION
The invention was made in view of the drawbacks inherent in the conventional examples, and an object thereof is to provide a breather apparatus for an internal combustion engine which can prevent blow-by gases from being blown up into a gas-liquid separation chamber by closing an oil return port in an ensured fashion without accumulating a large amount of oil separated from blow-by gases in the gas-liquid separation chamber, and further can promote the gas-liquid separation effect with a simple construction.
With a view to attaining the object, according to a first aspect of the invention, there is provided a breather apparatus for an internal combustion engine in which an opening at a lower end of a circumferential wall of a cylinder head cover which defines an internal upper space within the cylinder head cover together with a top wall of the cylinder head cover is closed with a bottom plate so as to form a gas-liquid separation chamber, wherein the bottom plate is inclined when the internal combustion engine is set in a normal posture, further wherein an oil return port is formed at a lowest portion along an edge of a lower side of the inclined bottom plate, further wherein a blow-by gas inlet port is provided at a position along an edge portion of an upper side of the bottom plate which edge portion faces the oil return port, and further wherein a guide wall is provided for guiding flows of blow-by gases that have flowed through the blow-by gas inlet port toward the oil return port such that the flows of blow-by gases are deflected at right angles before the oil return port.
Since the guide wall deflects and guides at right angles the flow of blow-by gases that have flowed in through the blow-by gas inlet port toward the oil return port before the oil return port, the risk is avoided that the flow of blow-by gases acts on oil which is about to flow out through the oil return port to thereby draw oil back into the gas-liquid separation chamber, thereby making it possible to promote the gas-liquid separation effect.
According to a second aspect of the invention, there is provided a brea
Konishi Yukio
Suganami Tomoji
Takehana Masahiro
Armstrong Westerman & Hattori, LLP
Honda Giken Kogyo Kabushiki Kaisha
McMahon Marguerite
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