Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1 0~ ;5
This invention has for its object an exhaust device for
internal combustion en~ines.
It has already been suggested to improve the performances
of certain internal combustion engines, to shape their exhaust
pipe with a diverging section then a converging section as seen
in the direction of the gas flow, such a device being sometimes
referred to as an "extractor". Besides, the fact that such de-
vices are only fully operational in a small operating range of
the engine, i.e. in a small range of rotational speeds, they do
not moreover enable to satisfy the imposed requirements of noise
level limitations for the exhaust of the engine which is equipped
with them.
Whereas there exists, in other respects, a large number
of silencer devices for internal combustion engines of the type
comprising deflectors or absorbing materials, such silencers
introduce by their construction perturbations in the flow of
exhaust gases, with generally results in a reduction in perfor-
mance of the engines with which they are associated.
It is an object of this invention to provide an exhaust
device for internal combustion engines which eliminates the di-
sadvantages of the above mentioned means and which, in particu-
lar, leads to an improvement in the performances of the engine
which is equipped with them, at least as significant as that
- obtained by means of devices of the "extractor" type, without
presenting the disadvantages inherant to these devices.
It is also another object of this invention to provide
such a device, which, contrarily to known devices of the "extrac-
tor" type, are operational in a very wide operating range of
the engine which is equipped with it.
According to this invention, an exhaust device for inter-
- 2 ~
lo~ s~s
nal combu~tion engines comprisinCJ an exhaust device for an in-
teInal combustion enginc comprisirlg a pipe which includes a
irst section having a progressively increasing cross-sectional
area and then a second section with a progressively decreasing
cross-.sectional area of exhaust gas flow as seen in the direct-
ion of flow of ths exhaust gases, said section with progressive-
ly decrea3in~ cross-sectional area of the exhaust gas flow com-
prising an external sub3t~ntially cylindrical envelope and a
streamlined member with an ogival or conical surface disposed
within said envelope substantially coaxially therewith such that
the exhaust gases flow without any disturbances of the fluid
stream, said cylindrical envelope having first and second ends,
said second end being downstream from said first end so that the
exhaust ~ases pass out of said device through said second end.
According to another feature of this invention, the
stream-lined member i~ movably mounted into the external enve~
lope along the axis thereof and in a preferred embodiment, such
movement is controlled relatively to the engine rating.
The invention will be better understood from the fol-
lowing description given as an example and with reference tothe accompanying drawing wherein
- figure 1 îs a diagrammatical longitudinal sectional
view of a device according to this invention,
- figure 2 is an end view oE the device as seen in the
direction of arrow A of figure 1,
- figure 3 is a view similar to that of figure 1, but
for an alternative embodiment.
An exhaust device for internal combustion engine ac-
cording to this invention, 10, igures 1 and 2, comprises a
diverging section 11 connected to an engine M. which extends,
in the direction of flow of the exhaust gases shown by an arrow
f, into
,, .
ss
an external envelope 12. Into the latter, preferably of cylin-
drical shape, is mounted by means of supports 13 and 14, a
stream-lined member 15 which defines in conjunction with the
envelope 12 an interval 16 with progressively decreasing cross-
section in the direction of flow of the exhaust gases.
In an embodiment, the stream-lined member 15 is shaped
according to an ogival or conical surface with a vertex 19 and
its axis 20 is preferably coaxial with the axis 21 of the en-
velope 12.
The stream-lined member 15 is preferably movably mounted
inside envelope 12 the direction of possible movement being that
of arrow f and the direction opposite thereto. This movement is
carried out by means, not shown, adapted to be controlled in
relationship with the rating of the engine through a connection
17 from a member 18, which can for example, be the throttle
lever of a motor-cycle engine or the accelerator pedal of a car
engine, when the engine is that of a motor vehicle.
The operation of a device according to this invention is
similar to that of a device of the "extractor" type in respect
of the flow of the exhaust gases. In the device of the invention,
however,
/the vertex 19 of the stream-lined member 15 acts upon the sound
wave system to cause a vihration node to appear at said vertex
with therefore a decrease in noise relatively to that generated
by a usual exhaust.
Complementarily, the longitudinally displaceable mounting
of the stream-lined member 15 and the control of the movement
subject to the rating of the engine, through connection 17 ena-
bles an automatical adjustment of the flow characteristics of
the exhaust gases in relation to the rotational rate of the
engine, the efficiency of which is thus improved continuously.
10~ 5
In an all:errlat.ivc embodi.ment, f:ig~re 3, on the totality or
on ~art o~ ~he length o the cnvel.ope L2, thon punched with
oponin-J.s, a aloavo meml~er 22 is added in an acoustically i80-
lating material ~IICh af; fiberglaf~s~ rock wool or the like en-
cloaed in an external tubing 23~
In ~uch a dcvice, the opcrat:ion of which is similar to
that of the embodiment described hereabove, the absorption of
the hlgh nound frequenc.ic.s by the sleeve 22 contributes to the
acl~ievement o a particularly satif;factory sound level.
