Intake manifold

Details Intake manifold Intake manifold

2000-01-14

2001-02-27

McMahon, Marguerite (Department: 3747)

Internal-combustion engines

Intake manifold

Passage to crankcase

C123S572000

Reexamination Certificate

active

06192848

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an intake manifold for a multi-cylinder engine and particularly, to an improvement in a structure of blow-by-gas passage in the same.
2. Description of the Related Art
A known intake manifold for a multi-cylinder engine is designed such that intake tubes are bound to groups or a single bundle to avoid interference between intake air flows and to distribute the air-flows uniformly.
Such a conventional intake manifold
1
comprises, as shown in
FIG. 5
, a collector
2
formed by aluminum die casting, a plurality of intake tubes
3
made of aluminum pipes, and an intake tube mount
4
formed by aluminum die casting for fixedly mounting the intake tubes
3
to the engine. The intake tubes
3
are bent to desired shapes and joined to the collector
2
and the intake tube mount
4
. One end of the collector
2
is connected to a blow-by gas tube
5
. when the cylinders are negatively pressurized, The blow-by gas tube
5
serves to feed back to the engine a mist of blow-by gas (oil mist) which has leaked through gaps at the piston rings to the crank case and contains some lubricant oil (and thus should not be discharged directly to the outside). The blow-by gas from the blow-by gas tube
5
is fed via an inner space
6
in the collector
2
to the intake tubes
3
as shown in FIG.
6
.
Another type of a known intake manifold has a structure shown in
FIGS. 7 and 8
, in which a communicating tube
7
communicates with the intake tubes
3
and is mounted as a branch to intermediate portions of the intake tube
3
for taking a blow-by gas via a tube
8
from the engine. The intake tubes
3
and the communicating tube
7
are made of cast iron. The communicating tube
7
is joined to the intake tubes
3
by pipes
9
.
The first known type of intake manifold
1
discussed above permits the single blow-by gas tube
5
to be connected to the inner space
6
of a considerable size to which the intake tubes
3
are also connected. This may cause blow-by gas to flow mostly into some of the intake tubes
3
located adjacent to the blow-by gas tube
5
. Therefore, only a small amount of blow-by gas flows into the other intake tubes
3
located far from the blow-by gas tube
5
, hence hardly providing uniform distribution of the blow-by gas to the intake tubes
3
. If the intake manifold
1
includes pipes each connected to their respective intake tube
3
for distributing the blow-by gas uniformly, its construction will be intricate thus increasing the cost.
The second known type of the intake manifold has the communicating tube
7
mounted to the intermediate portions of the intake tubes
3
and is complicated in the structure. Also, because the communicating tube
7
is joined by the intake tubes
3
by the pipes
9
, measures against vibration of the pipes
9
are needed.
SUMMARY OF THE INVENTION
The present invention is intended to eliminate the foregoing problems and its object is to provide an intake manifold capable of distributing blow-by gas to the intake tubes uniformly and easily with the use of a simple construction and without accounting for measures against vibration.
According to the present invention, an intake manifold having a collector and a plurality of intake tubes connected to the collector for feeding intake air to corresponding cylinders of an engine comprises a blow-by gas passage formed integral with the surface of the collector adjacent to the proximal ends of the intake tubes where the intake tubes are connected to the collector. Through apertures are formed in both sides of the blow-by gas passage for communicating the blow-by gas passage with the proximal ends of the intake tubes, thus eliminating the foregoing problems.
Thus, the intake manifold according to the present invention has the blow-gas passage formed on the surface of the collector and provided with the through apertures to communicate with the intake tubes, whereby the through apertures can easily be machined for having desired cross section and direction. Accordingly, with a simple construction, the distribution of blow-by gas to the cylinders will be uniform due to the corresponding cross sections and directions of the through apertures. In particular, the blow-by gas passage in the intake manifold of the present invention is formed on the surface of the collector and is thus simple in the construction and requires no measures against vibration.
The blow-by gas passage may be ridged on the surface of the collector.
Also, the manifold may further comprise intake tube mounting rings formed upright on the surface of the collector adjacent to the blow-by gas passage so that the inside of the proximal ends of the intake tubes fitted into the intake tube mounting rings communicates with the through apertures.
Moreover, it may be arranged that the intake tubes are connected to the collector so that their axes extend across two substantially parallel straight lines and the blow-by gas passage is arranged to extend in parallel to and between the two straight lines and connected at both sides to the intake tubes.


REFERENCES:
patent: 4790287 (1988-12-01), Sakurai et al.
patent: 6009863 (2000-01-01), Tochizawa
patent: 6089199 (2000-07-01), Lohr et al.

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