Note: Descriptions are shown in the official language in which they were submitted.
CA 02319292 2000-11-14
AN AIR INTAKE SILENCER
Backgiround of the Invention
1. Field of the Invention
The present invention relates to devices intended to reduce unwanted sounds
created by internal combustion engines, and more specifically, to structure
for decreasing
the amount and intensity of sound produced by the air intake of such engines.
2. Description of Related Art
Throughout the world, governments concerned with the spread of noise pollution
have enacted or are considering enacting legislation and/or regulations aimed
at lessening
the amount and effects) of that pollution. Those efforts are, in part,
directed at limiting
sound energy emissions provided by internal combustion engines utilized in
both small and
large scale vehicles, including emissions produced by grounds-care equipment.
To address
the restraints imposed by this legislation on permitted emissions levels,
industry has sought
to reduce the level of noise associated with both the exhaust and air
induction systems of
these engines.
With regard to the air induction system of internal combustion engines,
devices
known as air intake silencers have often been used to muffle, and therefore
reduce, the
noticeability of sound energy caused by these engines. With air as the medium
through
which sound travels, silencers of this type assist in reducing sound energy
created when air
is introduced into the engine from the atmosphere. This is in opposition to
exhaust systems
whereby sound is produced as air exits the engine. This energy often takes the
form of
noise, the loudness of that noise corresponding to the chosen engine speed
upon entry of air
into the silencer.
The design of intake silencers has included structure composed of several
components requiring connection by welding or other means. For example, one
construction
includes an open dampening shell having covers welded thereon at its ends.
Thereafter,
inlet and outlet piping is then attached, by additional welds, to the
periphery of apertures
provided in the covers for accommodating the flow of air through the shell.
Although designs
of this type have been capable of performing a silencing function, materials
and construction
costs remain as areas in which improvement can be viewed as advantageous.
Summaryr of the Invention
Thus, in order to obtain an economically advantageous construction, there is
provided a silencer formed as a one-piece structure. This structure is formed
according to
the principles of rotational molding thereby reducing the expense of
fabrication. Preferably,
the mold will be constructed of plastic in the form of cross-linked
polyethelene. Alternatively,
composite materials could be substituted.
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To permit air flow into an engine of vehicle, the silencer is constructed of a
main body
equipped with an inlet to which suitably fitting tubing can be attached to
direct air into the
inlet. Paralleling the inlet on an opposing side of the silencer is an outlet
through which air is
delivered to the engine. Those of ordinary skill in the art will recognize
that designation of
the inlet and outlet may be interchanged.
Forming the above inlet and outlet are two pipe-like formations molded as part
of the
overall silencer body. These formations are laterally spaced apart from one
another and are
substantially similar in the preferred embodiment. Formation of each of the
inlet and outlet
pipes in this manner enables the main body to be formed from a single mold
while also
creating an air flow path through the main body. Optimum silencing effect may
be achieved
by tailoring the dimensions and thus, the volume, of the main body to the
engine with which
the silencer is to be used. Such tailoring will permit an adequate and
appropriately sized
flow path so that as air is introduced into the engine during operation, the
engine is not
starved of air, thereby avoiding engine stall. It is contemplated that the
silencer of the instant
invention may be used with an engine equipped with either a carburetor or
injector fuel
delivery system.
Further delivery of air to the engine is accomplished by travel through
additional
tubing connected to the outlet and to an attached air filter flowing to the
engine.
Thus, there is provided a simple and economical air intake silencer allowing
for the
introduction of air into a vehicle engine while silencing the effect of that
entry.
Brief Descriation of the Drawingis
FIG. 1 is a front perspective view of the silencer of the present invention
connected
with an air filter.
FIG. 2 is an exploded view corresponding to the illustration of FIG. 1.
FIG. 3 is a top perspective view of the silencer according to the present
invention and
illustrating the inlet of the silencer.
FIG. 4 is a cross-sectional view taken along lines 4--4 of FIG. 3 illustrating
an outline
of the silencer.
Description of the Preferred Embodiment
Looking at Figures 1-2, there is illustrated the silencer 10 of the instant
invention
which may be arranged within and connected with an internal combustion engine
(not
shown). Further, it can be seen that air is to be directed into the silencer
10 through a length
of tubing 12 having, preferably, a tapered end 14 and a rounded end 16.
Connected with the
rounded end 16 is an inlet pipe 18 of silencer 10 set within a pocket 20
extending
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CA 02319292 2000-11-14
downwardly from a top surface 22, as best seen in Figure 3. Spaced from inlet
18 is a first
concave surface 24 formed within top surface 22. This concave 24 provides
structural
rigidity to silencer 10. On a bottom surface 26 is formed a pocket 28 and an
outlet pipe 30,
formed within the pocket 28 which is similar to pocket 20, through which air
travels toward
the engine. With like appearance as to top surface 22, a second concave
surface 32 shown
in Figure 4 is formed across from outlet 30 on bottom surface 26.
Returning to Figures 1-2, it will be seen that silencer 10 is connected to an
air filter 34
by a tubular elbow 36 at outlet 30. As air travels through filter 36, it is
then directed toward
engine 12 by an intake pipe 38.
Shown in Figure 4 is a cutaway view of silencer 10 taken along lines 4--4 of
Figure 3.
This view illustrates the interior flow path and silencer structure relative
to a generally
cylindrical side surface 40. As can be seen, the inlet 18 and outlet 30 take
the form of
generally cylindrical tubes having therein respective end portions within the
silencer
overlapping one another. Accordingly, an interior end portion 42 of inlet 18
is located close
to bottom surface 26 while an end portion 44 of outlet 30 is located closer to
top surface 22.
Together with pockets 20 and 28, parallel extension of inlet 18 and outlet 30
relative to each
other in this manner serves to define an air path depicted by the directional
arrows A
provided in Figure 4.
Flow of air through the silencer 10 is as follows. Air is first introduced
into the engine
(not shown) during its operation through tubing 12 wherein it then flows into
silencer 10 via
inlet 18. Upon movement beyond inlet 18, the stream of air is then smoothed
upon
encountering convex surfaces or deflectors 46, 48 which are opposite concave
surfaces 32
and 24, respectively, on an interior of the silencer 10. After impacting
deflector 46, the
stream is then caused to flow through a channel 50 for delivery into outlet
30, where it then
exits the silencer 10 and proceeds toward the engine.
Reduction of sound energy, in the form of noise resulting from the engine's
operation,
is attributable to at least two factors. First, silencer 10 is a reactive type
silencer wherein a
portion of sound produced by the engine enters the silencer 10 and is then
reflected back
towards the engine. This reflection back is caused, significantly, by the
structural mold of the
interior of the silencer 10. Accordingly, a large portion of sound does not
radiate outwardly
away from the engine toward the atmosphere. Secondly, sound traveling through
the interior
of the silencer 10, and outwardly toward the atmosphere, as shown by the
directional arrows
B in Figure 4, is dampened in terms of its acoustic intensity. This dampening,
as well as the
reflection back mentioned above, is caused by the indirect path created by the
convergence
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of inlet 18 and outlet 30 at channel 50 and shown by the arrows B in Figure 4,
in which
sound must travel as it leaves the silencer 10. Travel along this path B
provides an
opportunity for a dampening of sound energy which is not reflected back toward
the engine.
As this dampening occurs, the level and intensity of sound emitted from the
silencer 10 is
decreased, thereby resulting in a less noticeable and more tolerable degree of
noise emitted
into the environment.
While the present invention has been described in conjunction with a specific
embodiment, it is understood that many alternatives, modifications, and
variations will be
apparent to those skilled in the art in light of the foregoing description.
Accordingly, this
invention is intended to embrace all such alternatives, modifications and
variations which fall
within the spirit and scope of the appended claims.
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