Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a resanator, and in
particular to a resonator for use on an air inlet tube
attached to an internal combustion engine.
Air is introduced into an automotive engine for
creating an air/gasoline mixture which fuels the engine.
Typically, the air passes through an air filter, an inlet
tube, a throttle body or carburetor and an intake or inlet
manifold to the cylinders of the engine. Sound generated in
the cylinders, i.e. engine noise travels back through the
manifold and the inlet tube.
Many attempts have been made to reduce or attenuate .
engine noise. Typical devices for sound attenuation are
described in for example Canadian Patent No. 703,518, issued
top E. Ludlow et al on February 9, 1965, and United States
Patents Nos. 3,111,191, issued to J. Bachert on November 19,
1963; 3,388,769, issued to R.J. Martoia on June 18, 1968;
3,612,268, issued to O.E. Rieder on December 1, 1969;
3,966,015, issued to W.A. Bychinsky on June 29, 1976;
4,124,092, issued to S. Kajiya et al on November 7, 1978;
4,132,286, issued to H. Hasui et al on January 2, 1979;
4,164,266, issued to L. Collin et al on August 14, 1979;
4,165,798, issued to G. Martinez on August 28, 1979;
4,172,508, issued to L.C. Moss et al on October 30, 1979;
4,281,742, issued to A. Scheuermann et al on August 4, 1981;
4,415,059, issued to Y. Hayashi on November 15, 1983;
4,418,790, issued to R.E. Agnew on December 6, 1983;
1
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4,538,701, issued to D.C. Lowery et al on September 3, 1985;
4,574,914, issued to R.T. Flugger on March 11, 1986;
4,623,035, issued to K. Schad et al on November 18, 1986;
4,848,513, issued to G. Csaszar on July 18, 1989; 4,874,062,
issued to K. Yanagida et al on October 17, 1989 and 4,890,691,
issued to C. Ching-ho on January 2, 1990.
It is well established that the geometry of a
resonator determines the sound attenuating efficiency of the
device. In this connection, reference is made to the
introductory portion of the Kajiya et al U.S. Patent No.
4,124,092 which succinctly sets out the physics of the
situation. It is readily apparent that the altering of
resonator dimensions affects noise attenuation. The mufflers
described in the above listed patents, and for that matter
mufflers in general are discrete devices which must be
installed in an inlet or exhaust system by interrupting the
system. Usually the muffler forms part of the system, and is
connected to tubes or pipes forming other parts of the system
by clamps or welding. Thus, the installation or removal of a
muffler is a somewhat difficult, time consuming and often
expensive job. Moreover, the structures used to achieve the
desired attenuation are often complicated and consequently
expensive to produce.
An object of the present invention is to solve the
above mentioned problems by providing a relatively simple,
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CA 02021871 2000-02-25
easily installed, resonator, which can be inserted into
existing inlet or exhaust systems.
Another object of the invention is to provide a
resonator which can readily be mass produced by blow molding
at relatively little expense.
Accordingly, the present invention relates to a
sound resonator device for use on a sound transmitting tube
connected to an engine comprising elongated casing means, said
casing means including two elongated, hollow sections of
arcuate cross section; hinge means interconnecting one side
edge of one section to one side edge of the other section,
whereby said sections can be wrapped around the sound
transmitting tube to define a hollow sleeve with the hinge
means extending longitudinally thereof; partition means in
each said section dividing the interior thereof into at least
one elongated, tortuous passage; and inlet means in each said
section for connecting the interior of said tube to the
passage in said section, whereby sound is attenuated running
movement along said tortuous passage.
The invention will be described in greater detail
with reference to the accompanying drawings, which illustrate
a preferred embodiment of the invention, and wherein:
Figure 1 is a schematic, isometric view of a
resonator in accordance with the present invention in the open
position;
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CA 02021871 2000-02-25
Figure 2 is a schematic, isometric view of the
resonator of Fig. 1 in the closed position around a duct;
Figure 3 is a cross section taken generally along
line III-III of Fig. 2;
Figure 4 is a schematic, isometric view of an engine
and resonator in accordance with the present invention;
Figure 5 is a schematic graph of sound pressure
level versus engine noise frequency for a vehicle with and
without the resonator of Figs. 1 to 3; and
Figure 6 is a schematic graph of sound pressure
level versus engine speed for a vehicle with and without the
resonator of Figs. 1 to 3.
With reference to Figs. 1 to 3, a resonator in
accordance with the present invention which is generally
indicated at 1 includes an elongated casing defined by a pair
of arcuate, hollow sections 2 and 3. The sections 2 and 3 are
pivotally interconnected along one side edge by a hinge 4.
The hinge 4 is merely a web of material integral with the
sections 2 and 3.
Each section 2 and 3 is concavo-convex in cross
section, and includes an outer wall 6, an inner wall 7 and end
walls 8. The side edges of the walls 6 and 7 are pinched
together. When folded together (Figs. 2 and 3), the sections
2 and 3 define an oval cross section tube or casing. The free
side edges of the casing are interconnected by a latch defined
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CA 02021871 2000-02-25
by a lug 10 on one section 2 and a detent 11 in the other
section 3. The walls 6 and 7 of each panel 2 and 3 are joined
by a pair of longitudinally extending straight partitions 12,
a T-shaped partition 13 and an L-shaped partition 14. The
partitions 12, 13 and 14 divide the interior of the sections 2
and 3 into
15
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elongated tortuous passages 16 (Fig. 3) of varying lengths.
An inlet nozzle 18 extends outwardly from the center of each
inner wall 8 of each panel 2 and 3. When the panels are
wrapped around a pipe or tube 19 (Figs. 2 and 3), the nozzles
18 project inwardly through an opening 20 in the pipe or tube.
The material used in the resonator is polyethylene,
polypropylene reinforced or rubber modified thermoplastic
polyolefin, an engineering material, e.g. a polyamide, ABS
(acrylobutadiene styrene or polyphenyl oxide). Rubber
modified thermoplastic polyolefin is preferred because of its
flexibility and ease of modification to obtain a high
specific gravity, e.g. 1.6 to 1.8. Higher mass is desired for
sound reduction. An example of a suitable rubber modified
thermoplastic polyolefin is Salflex 355EX-S (trademark)
available from Salflex Polymers Ltd., Concord, Ontario.
As shown in Figs. 2 and 4, in use the resonator 1 is
mounted on a pipe or tube - in this case a flexible air intake
tube 21, which carries air from its inlet end 22 through a
throttle 23 and an intake manifold 24 to an automobile engine
25. The geometry of the passages 16 can readily be changed to
attenuate noises at different frequencies. The graph of Fig.
5 is a simplistic representation of the results of tests using
the resonator 1 of Figs. 1 to 3. It will be noted that with
no resonator 1 on the intake tube the noise level (plot A) at
certain frequencies is substantially higher than the noise
level (plot B) when the resonator 1 is installed on the
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CA 02021871 2000-02-25
intake or inlet tube 21. Figure 6 is a graph of expected
overall sound pressure level in decibels versus engine speed
for a vehicle without the resonator l (the solid upper line on
the graph) and for a vehicle using the resonator 1 (the broken
lower line). It has been found that a dramatic decrease in
the sound pressure level can be realized by using a resonator
1 of the type described herein.
It will be appreciated that the interior of the
sections 2 and 3 can be in fluid communication with each other
in the area of the hinge 4. Thus, in its simplest form, the
device of the present invention includes one inlet nozzle 18 w
and a single elongated tortuous passage 16. Moreover, the
geometry and the number of sections can be changed, provided
that the sections can be wrapped around a tube or pipe to
surround the latter.
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