U.S. patent number RE42,490 [Application Number 12/911,938] was granted by the patent office on 2011-06-28 for device and method for amplifying suction noise.
This patent grant is currently assigned to Nissan Motor Co., Ltd.. Invention is credited to Takeharu Sasaoka, Hiroshi Shimada, Shinichi Takeuchi.
United States Patent |
RE42,490 |
Takeuchi , et al. |
June 28, 2011 |
Device and method for amplifying suction noise
Abstract
A device for amplifying the suction noise of a vehicle is
disclosed. The device comprises an intake duct, a connecting pipe
and a composite membrane. The intake duct is for feeding air to an
engine intake port. A connecting pipe is connected to an interior
of the intake duct. The composite membrane is positioned within the
connecting pipe. The composite member blocks an interior passage
formed in the connecting pipe. The composite member further
includes at least two elastic membranes with one of masses and
rigidities that different from each other. A method is also
disclosed.
Inventors: |
Takeuchi; Shinichi (Ebina,
JP), Shimada; Hiroshi (Machida, JP),
Sasaoka; Takeharu (Sagmihara, JP) |
Assignee: |
Nissan Motor Co., Ltd.
(Yokohama-shi, Kanagawa, JP)
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Family
ID: |
38523465 |
Appl.
No.: |
12/911,938 |
Filed: |
October 26, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
11810058 |
Jun 4, 2007 |
7717230 |
May 18, 2010 |
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Foreign Application Priority Data
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Jun 5, 2006 [JP] |
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2006-155945 |
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Current U.S.
Class: |
181/271;
123/184.55; 123/184.56; 180/296; 180/68.3; 123/184.57; 123/184.54;
123/184.53; 180/309; 181/174; 181/167 |
Current CPC
Class: |
F02M
35/112 (20130101); F02M 35/1294 (20130101); F02M
35/10295 (20130101); F02M 35/10301 (20130101); F02M
35/10321 (20130101); F02M 35/161 (20130101); F02M
35/1272 (20130101) |
Current International
Class: |
F01N
1/16 (20060101) |
Field of
Search: |
;181/271,250,202,18,167,174,212,214
;123/184.53,184.54,184.55,184.56,184.57 ;340/381.1,438,439,384.3
;180/309,296,68.3 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 704 617 |
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Apr 1996 |
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EP |
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1 111 228 |
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Jun 2001 |
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EP |
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1 772 614 |
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Apr 2007 |
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EP |
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1 808 594 |
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Jul 2007 |
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EP |
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2000045895 |
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Feb 2000 |
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JP |
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2000303925 |
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Oct 2000 |
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JP |
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2005139982 |
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Jun 2005 |
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JP |
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2005/045225 |
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May 2005 |
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WO |
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Primary Examiner: Enad; Elvin G
Assistant Examiner: Phillips; Forrest M
Attorney, Agent or Firm: Young Basile
Claims
What is claimed is:
1. A method for amplifying the suction noise of a vehicle,
comprising: passing variations in air pressure transmitted into an
engine intake port through a pipe that is connected to an engine,
the variations in air pressure resulting in intake pulsations
having one of at least two different frequencies; resonating a
first elastic member of a composite membrane at one of the at least
two different frequencies; resonating a second elastic member of
the composite membrane at the other one of the at least two
different frequencies; and varying the air pressure transmitted to
an external air side in response to one of the resonated first
elastic member and the resonated second elastic member.
2. A device for amplifying the suction noise of a vehicle,
comprising: an intake duct for feeding air to an engine intake
port, a connecting pipe connected to an interior of the intake
duct, and a composite membrane positioned within the connecting
pipe, wherein the composite membrane blocks an interior passage
formed in the connecting pipe, wherein the composite membrane
includes at least two elastic membranes with one of masses and
rigidities that differ from each other, each of the at least two
elastic membranes vibrating in response to a different intake
pulsation frequency.
3. The device for amplifying the suction noise of a vehicle
described in claim 2, wherein the composite membrane further
comprises a rigidity changing portion formed between the at least
two elastic membranes, with the rigidity of the rigidity changing
portion being different from that of the at least two elastic
membranes.
4. The device for amplifying the suction noise of a vehicle
described in claim 3, wherein the rigidity changing portion is one
of a convex portion and concave portion formed on the surface of
the composite membrane.
5. The device for amplifying the suction noise of a vehicle
described in claim 3, wherein the rigidity changing portion further
comprises a core member with a rigidity higher than that of the
elastic membranes.
6. The device for amplifying the suction noise of a vehicle
described in claim 3, wherein the rigidity changing portion further
comprises: at least an annular rigidity changing portion of one of
a circular and elliptical shape and arranged inward of an outer
periphery of the composite membrane, and radial rigidity changing
portions that extend from said annular rigidity changing portion to
the outer periphery of the composite membrane, and which divide the
region between the portion surrounded by the annular rigidity
changing portion and the outer periphery of the composite membrane
into at least two portions.
7. The device for amplifying the suction noise of a vehicle
described claim 3 wherein the at least two elastic membranes have
different areas from each other.
8. The device for amplifying the suction noise of a vehicle
described claim 7 wherein the rigidity changing portion refers to
one of a convex portion and concave portion formed on a surface of
the composite membrane.
9. The device for amplifying the suction noise of a vehicle
described in claim 7 wherein the rigidity changing portion further
comprises a core member with a rigidity higher than that of the
elastic membranes.
10. The device for amplifying the suction noise of a vehicle
described in claim 7 wherein the rigidity changing portion further
comprises: at least an annular rigidity changing portion of one of
a generally circular and elliptical shape that is arranged inward
of an outer periphery of the composite membrane, and radial
rigidity changing portions that extend from the annular rigidity
changing portion to the outer periphery of the composite membrane,
and which divide the region between the portion surrounded by the
annular rigidity changing portion and the outer periphery of the
compo site membrane into at least two portions.
11. The device for amplifying the suction noise of a vehicle
described in claim 2, wherein at least two elastic membranes are
made of materials having one of different moduli and densities from
each other.
12. The device for amplifying the suction noise of a vehicle
described in claim 11 wherein: the composite membrane has a
rigidity changing portion formed between the at least two elastic
membranes, with the rigidity of the rigidity changing portion being
different from that of the at least two elastic membranes.
13. The device for amplifying the suction noise of a vehicle
described in claim 12, wherein the rigidity changing portion is one
of a convex portion and concave portion formed on the surface of
the composite membrane.
14. The device for amplifying the suction noise of a vehicle
described in claim 12 wherein the rigidity changing portion further
comprises a core member with a rigidity higher than that of the
elastic membranes.
15. The device for amplifying the suction noise of a vehicle
described in claim 12 wherein the rigidity changing portion further
comprises: at least an annular rigidity changing portion of one of
a generally circular and elliptical shape that is arranged inward
of an outer periphery of the composite membrane, and radial
rigidity changing portions that extend from the annular rigidity
changing portion to the outer periphery of the composite membrane,
and which divide the region between the portion surrounded by the
annular rigidity changing portion and the outer periphery of the
composite membrane into at least two portions.
16. The device for amplifying the suction noise of a vehicle
described in claim 12 wherein the at least two elastic membranes
have different thicknesses from each other.
17. The device for amplifying the suction noise of a vehicle
described in claim 16 wherein the composite membrane further
comprises a rigidity changing portion formed between the at least
two elastic membranes, with the rigidity of the rigidity changing
portion being different from that of the at least two elastic
membranes.
18. The device for amplifying the suction noise of a vehicle
described in claim 17 wherein the rigidity changing portion is one
of a convex portion and concave portion formed on a surface of the
compo site membrane.
19. The device for amplifying the suction noise of a vehicle
described in claim 17 wherein the rigidity changing portion further
comprises a core member with a rigidity higher than that of the
elastic membranes.
20. The device for amplifying the suction noise of a vehicle
described in claim 17 wherein the rigidity changing portion further
comprises: at least an annular rigidity changing portion of one of
a generally circular or elliptical shape and arranged inward of an
outer periphery of the composite membrane, and radial rigidity
changing portions that extend from the annular rigidity changing
portion to the outer periphery of the composite membrane, and which
divide the region between the portion surrounded by the annular
rigidity changing portion and the outer periphery of the composite
membrane into at least two portions.
21. A device for amplifying the suction noise of a vehicle,
comprising: intake means for feeding air to an engine intake port,
pipe means fluidly connected to the intake means, and composite
membrane means positioned within the pipe means, wherein the
composite membrane means blocks an interior passage formed in the
pipe means, wherein the composite membrane means includes at least
two elastic membranes with one of masses and rigidities that differ
from each other, each of the at least two elastic membranes adapted
to vibrate in response to a different intake pulsation frequency.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority from Japanese Patent Application
Serial No. .[.2006-155944.]. .Iadd.2006-155945 .Iaddend.filed Jun.
5, 2006.[., the disclosure of which, including its specification,
drawings and claims, are incorporated herein by reference in its
entirety.]..
TECHNICAL FIELD
The present disclosure pertains to a type of device for improving
the sound quality of a suction noise generated by an intake system
of an automobile or the like.
BACKGROUND
Japanese Patent No. 3613665 describes a known device that boosts
suction noise. The device described therein is for amplifying
suction noise and has plural intake ducts having resonance
frequencies that are different from each other, so that it is
possible to boost the suction noise at different frequencies, and
permits introduction of suction noise into the vehicle passenger
compartment.
However, the device for amplifying suction noise described in
Japanese Patent No. 3613665 has some disadvantages. First, because
the device is constituted with plural intake ducts, there is no
leeway in the space required inside the engine compartment. Thus,
there are restrictions on the layout, and the device is difficult
to install in the engine compartment.
SUMMARY
The present disclosure provides a device to boost the suction noise
of a vehicle characterized by the fact that resonance of an elastic
membrane, due to variation in pressure of air transmitted into an
engine intake port, is allowed to occur at least two different
frequencies.
According to the present disclosure, it is possible to boost
suction noise at plural frequencies without the need of plural
intake ducts, so that it is possible to generate impressive suction
noise, and at the same time to improve the freedom of design
layout.
One embodiment of the disclosure includes a device for amplifying
the suction noise of a vehicle. The embodiment of the device
comprises an intake duct, a connecting pipe and a composite
membrane. The intake duct is for feeding air to an engine intake
port. A connecting pipe is connected to an interior of the intake
duct. The composite membrane is positioned within the connecting
pipe. The composite member blocks an interior passage formed in the
connecting pipe. The composite member further includes at least two
elastic membranes with one of masses and rigidities that different
from each other. A method is also disclosed.
BRIEF DESCRIPTION OF DRAWINGS
Other features and advantages of the present disclosure will be
apparent from the ensuing description, taken in conjunction with
the accompanying drawings, in which:
FIG. 1A is a side elevational view of a vehicle equipped with a
device for amplifying a suction noise of a vehicle.
FIG. 1B is a top plan view of the vehicle of FIG. 1A.
FIG. 1C is a front elevational view of the vehicle of FIG. 1A.
FIG. 2 is a diagram illustrating the structure of the device for
amplifying suction noise according to a first embodiment.
FIG. 3 is a diagram illustrating in detail the structure of a
composite membrane.
FIG. 4 is a diagram illustrating a vibration state of each elastic
membrane in an out-of-plane direction of the composite membrane
during a first acceleration mode.
FIG. 5 is a diagram illustrating a vibration state of each elastic
membrane in the out-of-plane direction of the composite membrane
during a second acceleration mode.
FIG. 6 is a diagram illustrating the vibration state of each
elastic membrane in an out-of-plane direction of the composite
membrane during a third acceleration mode.
FIG. 7 is a diagram illustrating the structure of a composite
membrane of the device for amplifying the suction noise of a
vehicle in a second embodiment.
FIG. 8 is a diagram illustrating the structure a composite membrane
of the device for amplifying the suction noise of a vehicle in a
third embodiment
FIG. 9 is a cross section of the composite membrane taken across
X-Y in FIG. 8.
FIGS. 10A-10C are diagrams illustrating modified examples of the
composite membrane of the device for amplifying the suction noise
of a vehicle in the third embodiment.
FIG. 11A-11D are diagrams illustrating modified examples of the
composite membrane of the device for amplifying the suction noise
of a vehicle in the third embodiment.
FIG. 12 is a diagram illustrating the structure of the composite
membrane of the device for amplifying the suction noise of a
vehicle in a forth embodiment.
FIG. 13 is a cross section of the composite membrane taken across
Y-Y in FIG. 12.
FIGS. 14A-14C are diagrams illustrating modified examples of the
composite membrane of the device for amplifying the suction noise
of a vehicle the fourth embodiment.
FIGS. 15A-15D are diagrams illustrating modified examples of the
composite membrane of the device for amplifying the suction noise
of a vehicle in the fourth embodiment.
FIG. 16 is a diagram illustrating the structure of a composite
membrane for the device for amplifying the suction noise of a
vehicle in a fifth embodiment.
DETAILED DESCRIPTION
While the claims are not limited to the illustrated embodiments, an
appreciation of various aspects of the apparatus is best gained
through a discussion of various examples thereof. Referring now to
the drawings, illustrative embodiments are shown in detail.
Although the drawings represent the embodiments, the drawings are
not necessarily to scale and certain features may be exaggerated to
better illustrate and explain an innovative aspect of an
embodiment. Further, the embodiments described herein are not
intended to be exhaustive or otherwise limiting or restricting to
the precise form and configuration shown in the drawings and
disclosed in the following detailed description. Exemplary
embodiments of the present invention are described in detail by
referring to the drawings as follows.
Embodiment 1
FIGS. 1A-1C includes diagrams illustrating a vehicle C carrying a
device 1 for amplifying suction noise according to a first
embodiment. FIG. 1A is a side view of a vehicle C. FIG. 1B is a top
view of vehicle C. And FIG. 1C is a front view of vehicle C.
As can be seen from FIG. 1, device 1 that boosts suction noise in
the first embodiment is arranged in front of a vehicle passenger
compartment 2. Indeed, device 1 is arranged in an engine
compartment 6 that is separated from vehicle passenger compartment
2 by a dash panel 4. Further, device 1 is arranged on an intake
duct 10 that is connected to an engine 8.
The resonant vibration of air in intake duct 10 takes place in air
intake duct 10. When resonance occurs, pressure variations develop
in air in intake duct 10, and these pressure variations in the air
are perceived by humans as noise. The noise accompanying intake is
called suction noise. The frequency of the suction noise depends on
the frequency of the pressure variations generated due to the
resonance phenomenon. The frequency of the pressure variation that
takes place due to the resonance phenomenon is determined by the
resonance frequency, which depends on the length of the intake
duct, etc.
FIG. 2 is a diagram illustrating the structure of device 1 that
amplifies the suction noise in the first embodiment. As shown in
FIG. 2, device 1 that amplifies the suction noise in the first
embodiment comprises a connecting pipe 12, an additional pipe 14,
and a composite membrane 16 (represented by dashed lines in FIG.
2).
In the embodiment shown, connecting pipe 12 is generally
cylindrical, and is attached to an outer peripheral surface of
intake duct 10, which may be formed of a draft tube with air inside
it. Connecting pipe 12 communicates with intake duct 10.
Similar to connecting pipe 12, additional pipe 14 may also be
generally cylindrical. A first opening at one end of additional
pipe 14 is connected to connecting pipe 12, and a second opening at
the other end of additional pipe 14 opens to external air.
Composite membrane 16 is generally disk-shaped and may be made of,
for example, rubber or another elastic material. Composite member
16 is attached on an inner peripheral surface of connecting pipe 12
and extends across an interior of connecting pipe 12 so as to close
connecting pipe 12. Composite membrane 16 undergoes elastic
deformation during intake by engine 8, corresponding to variation
in an intake vacuum generated in air inside intake duct 10, so that
vibration of composite membrane 16 occurs in an out-of-plane
direction. The detailed structure of composite membrane 16 will be
explained later.
The structure of intake duct 10 and the parts related to thereto
will now be explained.
Intake duct 10 forms an intake path from the external air to engine
8, and is comprised of a dust side intake duct 20 and a clean side
intake duct 18.
A first opening at one end of dust side intake duct 20 is connected
to an air cleaner 22, and a second opening at the other end of dust
side intake duct 20 opens to the external air.
Clean side intake duct 18 includes a throttle chamber 24. A first
opening at one end of clean side intake duct 18 is connected to air
cleaner 22, and a second opening at the other end of clean side
intake duct 18 is connected via a surge tank 26 to various portions
of an intake manifold 28 to the various cylinders (not shown in the
figure) of engine 8.
For example, air cleaner 22 includes an oiled filter or other
filter part for cleaning air flowing from the second opening at one
end of dust side intake duct 10 as it passes through the filter
portion.
Throttle chamber 24 is installed between air cleaner 22 and surge
tank 26, and is connected to an accelerator pedal (not shown in the
figure). Throttle chamber 24 adjusts the airflow rate from air
cleaner 22 to surge tank 26 corresponding to the amount of
accelerator pedal depression. When the amount of accelerator pedal
depression is reduced, the airflow rate from air cleaner 22 to
surge tank 26 is decreased, so that the rotational velocity of
engine 8 falls, and at the same time the intake vacuum generated in
the air inside intake duct 10 is reduced. On the other hand, when
the amount of accelerator pedal depression is increased, the
airflow rate from air cleaner 22 to surge tank 26 is increased, so
that the rotational velocity of engine 8 rises, and at the same
time, the intake vacuum generated in the air in intake duct 10 is
increased.
During intake, engine 8 draws air that has flowed from the opening
at the second end of dust side intake duct 20 and is present inside
clean side intake duct 18 into the various cylinders via surge tank
26 and intake manifold 28.
Also, in conjunction with the intake operation, engine 8 becomes a
pressure source that generates intake pulsation in the air inside
intake duct 10, and this intake pulsation results in suction
noise.
Here, the intake pulsation that occurs in conjunction with the
intake operation of engine 8 is a pressure variation generated in
the air inside intake duct 10. This pressure variation is composed
of plural pressure variations at different frequencies. That is,
the intake pulsation that occurs in conjunction with the intake
operation of engine 8 is composed of plural intake pulsations at
different frequencies. In the first embodiment, engine 8 is assumed
to be a 6-cylinder in-line engine. However, engine 8 is not limited
to this construction.
FIG. 3 is a diagram illustrating the detailed structure of
composite membrane 16.
Viewed in the thickness direction of composite membrane 16, as may
be seen, composite membrane 16 includes three elastic membranes
30a-30c. Elastic membranes 30a-30c are separated from each other by
slots 32 formed in the surface on an intake duct side of composite
membrane 16. In the embodiment shown, and slots 32 are formed in
shapes having different areas. More specifically, area Sa of
elastic membrane 30a is larger than area Sb of elastic membrane
30b, and area Sb of said elastic membrane 30b is larger than area
Sc of elastic membrane 30c. That is, elastic membranes 30a-30c are
formed to satisfy the relationship Sa>Sb>Sc.
Here, because elastic membranes 30a-30c have different areas from
each other, their resonance frequencies for vibration in the
out-of-plane direction of composite membrane 16 are different from
each other.
The resonance frequency is that for vibration at a prescribed
frequency detected when an object is allowed to vibration freely.
Any object has a natural resonance frequency. Usually, an object
has plural resonance frequencies. The resonance frequency depends
on the rigidity and mass of the object. More specifically, the
higher the rigidity, the higher the resonance frequency, while the
larger the mass, the lower the resonance frequency. Here, rigidity
refers to the proportionality coefficient between a bending or
twisting force applied to the structural body and the deflection of
the structural body as a whole.
Consequently, because elastic membranes 30a-30c have different
areas, they differ from each other in rigidity and mass. As a
result, they have different resonance frequencies.
Compared with elastic membrane 30c with a smaller area, elastic
membrane 30a with a larger area has a lower resonance frequency for
vibration in the out-of-plane direction. Consequently, for said
elastic membranes 30a-30c, assuming the resonance frequency of
elastic membrane 30a to be first resonance frequency f1, the
resonance frequency of elastic membrane 30b to be second resonance
frequency f2, and the resonance frequency of elastic membrane 30c
to be third resonance frequency f3, the following conditional
relationship among them applies: f1<f2<f3.
Also, elastic membranes 30a-30c are appropriately formed such that
their resonance frequencies correspond to intake pulsation at a
first frequency, intake pulsation at a second frequency and intake
pulsation at a third frequency selected from among the intake
pulsations at plural frequencies that form the intake pulsation
generated in conjunction with the intake operation of engine 8.
More specifically, first resonance frequency f1 of elastic membrane
30a matches the first intake pulsation frequency, second resonance
frequency f2 of elastic membrane 30b matches the second intake
pulsation frequency, and third resonance frequency f3 of elastic
membrane 30c matches the third intake pulsation frequency.
Here, the first frequency is lower than the second frequency and
the second frequency is lower than the third frequency. That is,
the first frequency, second frequency and third frequency satisfy
the following relationship: first frequency<second
frequency<third frequency.
The first frequency is the frequency of the intake pulsation
generated when the engine rotates at a prescribed rotational
velocity R1, the second frequency is the frequency of the intake
pulsation generated at a prescribed rotational velocity R2, and the
third frequency is the frequency of the intake pulsation generated
at a prescribed rotational velocity R3.
Here, R1 is a rotational velocity lower than R2 and R2 is a
rotational velocity lower than R3. That is, rotational velocities
R1, R2, R3 satisfy the following relationship: R1<R2<R3.
In addition, each of slots 32 is formed between two adjacent
elastic membranes, and they form rigidity changing portions having
different rigidities from those of elastic membranes 30a-30c.
The operation of the first embodiment of device 1 that amplifies
the suction noise will now be explained.
When engine 8 is started, the intake pulsation generated in
conjunction with the intake operation of engine 8 is propagated via
intake manifold 28 and surge tank 26 into the air inside intake
duct 10 (see FIG. 2).
While engine 8 is running, as the amount of accelerator pedal
depression is increased, the airflow rate from air cleaner 22 to
surge tank 26 is increased (hereinafter to be referred to as
acceleration mode). As a result, while the rotational velocity of
engine 8 is increased, the intake vacuum generated for the air in
intake duct 10 rises (see FIG. 2).
In the following, the operation of elastic membranes 30a-30c in the
acceleration mode will be explained in more detail with reference
to FIGS. 4-6.
FIGS. 4-6 are diagrams illustrating the vibration of elastic
membranes 30a-30c in the out-of-plane direction of the composite
membrane 16 during the acceleration mode. FIG. 4 is a diagram
illustrating the state when the rotational velocity of the engine
is R1; FIG. 5 is a diagram illustrating the state when the
rotational velocity of the engine is R2; and FIG. 6 is a diagram
illustrating the state when the rotational velocity of the engine
is R3.
When the rotational velocity of the engine is R1, among the plural
intake pulsations at different frequencies that form the intake
pulsation generated in conjunction with the intake operation of the
engine, an intake pulsation at the first frequency is propagated
via connecting pipe 12 to composite membrane 16.
As illustrated in FIG. 4, because in this case the frequency of the
intake pulsation at the first frequency matches first resonance
frequency f1 of elastic membrane 30a, only elastic membrane 30a
among the elastic membranes 30a-30c vibrates in the out-of-plane
direction of composite membrane 16. When elastic membrane 30a
vibrates in the out-of-plane direction of composite membrane 16, it
causes pressure variations in the air in additional pipe 14 on the
side of composite membrane 16 that is open to the external air.
There, air pressure variations become noise that is emitted to an
external air side, and the suction noise is thereby amplified.
When the amount of accelerator pedal depression is further
increased, that is, when the rotational velocity of the engine is
at R2, among the plural intake pulsations at different frequencies
that form the intake pulsation in conjunction with the intake
operation of the engine, the intake pulsation at the second
frequency is propagated via connecting pipe 12 to composite
membrane 16.
As shown in FIG. 5, because in this case the frequency of the
intake pulsation at the second frequency matches second resonance
frequency f2 of elastic membrane 30b, only elastic membrane 30b
among elastic membranes 30a-30c vibrates in the out-of-plane
direction of composite membrane 16. When elastic membrane 30b
vibrates in the out-of-plane direction of composite membrane 16, it
causes pressure variations in the air between composite membrane 16
and the second opening of additional pipe 14, and said air pressure
variations become noise that is emitted to the external air side,
and the suction noise is thereby amplified.
When the amount of accelerator pedal depression is further
increased, that is, when the rotational velocity of the engine is
at R3, among the plural intake pulsations at different frequencies
that form the intake pulsation in conjunction with the intake
operation of the engine, the intake pulsation at the third
frequency is propagated via connecting pipe 12 to composite
membrane 16.
As shown in FIG. 6, because in this case the frequency of the
intake pulsation at the third frequency matches third resonance
frequency f3 of elastic membrane 30c, only elastic membrane 30c
among elastic membranes 30a-30c vibrates in the out-of-plane
direction of composite membrane 16. When elastic membrane 30c
vibrates in the out-of-plane direction of composite membrane 16, it
causes pressure variations in the air in additional pipe 14 on the
side of composite membrane 16 that is open to the external air, and
air pressure variations become noise that is emitted to the
external air side, and therefore the suction noise is
amplified.
Consequently, in the acceleration mode, elastic membranes 30a-30c
with different resonance frequencies vibrate in the out-of-plane
direction of the composite membrane according to variation in the
rotational velocity of the engine. As a result, the suction noise
at the first frequency, the suction noise at the second frequency
and the suction noise at the third frequency are amplified, and the
amplified suction noise is emitted to the external air side from
the second opening at the additional pipe 14 (see FIG. 2).
When the amplified suction noise is emitted to the external air
side from the second opening of additional pipe 14, the emitted
suction noise is propagated via the air into vehicle passenger
compartment 2 such that an impressive suction noise is transmitted
into vehicle passenger compartment 2 (see FIG. 1).
Variations of Embodiment 1
For device 1 that amplifies the suction noise in the first
embodiment, three elastic membranes 30a-30c are formed to have
different resonance frequencies for vibration in the out-of-plane
direction of composite membrane 16. However, it is understood that
the present embodiment is not limited to this scheme. Indeed, a
scheme may also be adopted in which among three elastic membranes
30a-30c, at least two elastic membranes have resonance frequencies
for vibration in the out-of-plane direction of the composite
membrane that are different from each other.
Also, for device 1 that amplifies the suction noise in the first
embodiment, three elastic membranes 30a-30c are formed to have
different resonance frequencies for vibration in the out-of-plane
direction of composite membrane 16 by virtue of having different
areas. The present embodiment is not limited to this scheme,
however. That is, a scheme may also be adopted in which three
elastic membranes 30a-30c are formed with the same area, and at the
same time, they are formed different from each other with respect
to rigidity and/or mass, so that the resonance frequencies for
vibration in the out-of-plane direction of the composite membrane
are different from each other. Here, to form an elastic membrane 30
having increased rigidity and/or mass, a core member may be
arranged inside it, or a processed mass body for forming ribs on
elastic membrane 30 may be attached, or the thickness of elastic
membrane 30 may be increased. As a result, although elastic
membrane 30 has the same area as the other elastic membranes,
elastic membrane 30 nevertheless has higher rigidity and/or larger
mass than the others. In this case, by selecting the rigidity
and/or mass of each elastic membrane 30a, 30b, 30c to meet the
required resonance frequency conditions for vibration in the
out-of-plane direction of composite membrane 16, it is possible to
set each elastic membrane 30a, 30b, 30c at a desired resonance
frequency.
In the first embodiment, device 1 that amplifies the suction noise
has a composite membrane 16 composed of three elastic membranes
30a-30c. The present embodiment is not limited to this scheme,
however. A scheme can also be adopted in which composite membrane
16 is composed of two elastic membranes 30 or more than three
elastic membranes 30.
Also, in the structure for device 1 that amplifies the suction
noise of the present embodiment, device 1 that amplifies the
suction noise is set in engine compartment 6 in front of vehicle
passenger compartment 2. However, other locations for device 1 that
amplifies the suction noise are contemplated. That is, for example,
when vehicle C has an engine compartment 6 arranged behind vehicle
passenger compartment 2, the location for device 1 that amplifies
the suction noise can be in engine compartment 6 located behind
vehicle passenger compartment 2. Also, for example, when vehicle C
has an engine compartment 6 beneath vehicle passenger compartment
2, the location for device 1 that amplifies the suction noise can
be within engine compartment 6 set beneath vehicle passenger
compartment 2. In any case, the location of device 1 that amplifies
the suction noise can be adjusted appropriately according to the
configuration of vehicle C, that is, the position of engine
compartment 6.
Viewing the device 1 for amplifying suction noise of the first
embodiment in the thickness direction of composite membrane 16, the
composite membrane 16 is composed of three elastic membranes 30a,
30b, 30c. Elastic membranes 30a, 30b, 30c have resonance
frequencies for vibrations in the out-of-plane direction of
composite membrane 16 that differ from each other.
As a result, in the acceleration mode, the various elastic
membranes 30a, 30b, 30c vibrate in the out-of-plane direction of
composite membrane 16 corresponding to variation in the rotational
velocity of the engine.
Consequently, the intake pulsation at the first frequency, and the
suction noises at the second frequency and third frequency are
amplified corresponding to variation in the rotational velocity of
the engine, and the amplified suction noise is emitted from the
second opening of additional pipe 14 on the external air side. The
emitted suction noise is propagated via the air into the vehicle
passenger compartment, so that an impressive suction noise is
transmitted into vehicle passenger compartment 2.
As a result, it is possible to generate the suction noise at plural
frequencies by via composite membrane 16, and it is possible to
generate an impressive suction noise without a requirement of
plural intake ducts. Because there is no need for plural intake
ducts in this embodiment, freedom of layout is improved, allowing
device 1 to be adopted on a variety of vehicles with different
constructions, such as vehicles having different body sizes.
Also, viewing the device for amplifying suction noise of the
present embodiment in the thickness direction, composite membrane
16 is comprised of three elastic membranes, and these elastic
membranes are formed with different areas, so that they have
different vibration frequencies in the out-of-plane direction of
composite membrane 16.
Consequently, by selecting the areas of the respective elastic
membranes corresponding to resonance frequencies for vibration in
the out-of-plane direction of composite membrane 16, it is possible
to set the resonance frequencies of the elastic membranes at the
respective desired resonance frequencies.
As a result, it is possible to set the resonance frequencies for
vibration in the out-of-plane direction of the various elastic
membranes comprising composite membrane 16 at the plural desired
frequencies, and it is possible to expand the frequency band range
where amplifying the suction noise can be realized. As a result, it
is possible to improve the sound quality of the suction noise
directed into the vehicle passenger compartment.
Second Embodiment
Turning to FIG. 7, a second embodiment will be explained. FIG. 7 is
a diagram illustrating the structure of composite membrane 16 for
device 1 for amplifying the suction noise of a vehicle.
As can be seen from FIG. 7, the structure of device 1 for
amplifying the suction noise of a vehicle C in the second
embodiment is the same as that of the first embodiment, except for
the structure of composite membrane 16. That is, composite membrane
16 in the second embodiment is divided by rigidity changing
portions 34 formed between every pair of adjacent elastic membranes
and having rigidities different from those of said elastic
membranes 30a-30d. Viewed in the thickness direction, composite
membrane 16 has four elastic membranes 30a-30d.
Rigidity changing portions 34 include an annular rigidity changing
portion 36 and radial rigidity changing portions 38a-38c.
Annular rigidity changing portion 36 is formed as a slot arranged
in the surface of composite membrane 16 on an intake duct side of
composite membrane 16. Annular rigidity changing portion 36 is
shaped to surround a portion of composite membrane 16 that includes
the center of composite membrane 16, and it has an overall circular
or elliptical shape. In the second embodiment, the center portion
surrounded with annular rigidity changing portion 36 is referred to
as elastic membrane 30d in the following description.
Similar to annular rigidity changing portion 36, radial rigidity
changing portions 38a-38c are formed as slots in the surface of
composite membrane 16 on the intake duct side of composite member
16, and annular rigidity changing portions 38a-38d extend from
annular rigidity changing portion 36 towards an outer periphery of
composite membrane 16, so that they divide the portions other than
that surrounded by annular rigidity changing portion 36 into plural
portions. With regard to radial rigidity changing portions 38a-38c
in the second embodiment, an example is explained in which three
radial rigidity changing portions 38a-38c are formed extending from
annular rigidity changing portion 36 towards the outer periphery of
composite membrane 16. Also, in explanation of the second
embodiment, the three elastic membranes 30 divided by said three
radial rigidity changing portions 38a-38c are described as elastic
membranes 30a-30c, respectively.
Elastic membranes 30a-30d are formed into shapes with different
areas by means of rigidity changing portions 34. More specifically,
area Sa of elastic membrane 30a is larger than area Sb of elastic
membrane 30b; area Sb of elastic membrane 30b is larger than area
Sc of elastic membrane 30c; and area Sc of elastic membrane 30c is
larger than area Sd of elastic membrane 30d. That is, elastic
membranes 30a-30d are formed to satisfy the following relationship:
Sa>Sb>Sc>Sd.
Also, because elastic membranes 30a-30d have different areas, their
resonance frequencies in the out-of-plane direction of composite
membrane 16 are different from each other. More specifically,
assuming the resonance frequency of elastic membrane 30a to be
first resonance frequency f1, the resonance frequency of elastic
membrane 30b to be second resonance frequency f2, the resonance
frequency of elastic membrane 30c to be third resonance frequency
f3, and the resonance frequency of elastic membrane 30d to be
fourth resonance frequency f4, the following relationship is
established: f1<f2<f3<f4.
Also, elastic membranes 30a-30d are appropriately shaped such that
their resonance frequencies match those of the intake pulsations at
the first frequency, the second frequency, the third frequency and
the fourth frequency, selected from among the intake pulsations at
plural frequencies that form the intake pulsation generated in
conjunction with the intake operation of engine 8. More
specifically, first resonance frequency f1 of elastic membrane 30a
matches the frequency of the intake pulsation at the first
frequency, second resonance frequency f2 of elastic membrane 30b
matches the frequency of the intake pulsation at the second
frequency, third resonance frequency f3 of elastic membrane 30c
matches the frequency of the intake pulsation at the third
frequency, and fourth resonance frequency f4 of elastic membrane
30d matches the frequency of the intake pulsation at the fourth
frequency.
Here, the first frequency is lower than the second frequency, the
second frequency is lower than the third frequency, and the third
frequency is lower than the fourth frequency. That is, the first
frequency, second frequency, third frequency and fourth frequency
satisfy the following relationship: first frequency<second
frequency<third frequency<fourth frequency.
The first frequency is the frequency of the intake pulsation
generated when the engine rotates at a prescribed rotational
velocity R1, the second frequency is the frequency of the intake
pulsation generated at a prescribed rotational velocity R2, the
third frequency is the frequency of the intake pulsation generated
at a prescribed rotational velocity R3, and the fourth frequency is
the frequency of the intake pulsation generated at a prescribed
rotational velocity R4.
Here, R1 is a rotational velocity lower than R2, R2 is a rotational
velocity lower than R3, and R3 is a rotational velocity lower than
R4. That is, rotational velocities R1, R2, R3, R4 satisfy the
following relationship: R1<R2<R3<R4.
The remaining structure of composite member 16 and device 1 is
substantially the same as that of in the first embodiment.
The operation of device 1 that amplifies the suction noise
according to the second embodiment will now be described. In the
following description, because the structure of everything besides
composite membrane 16 is substantially the same as in the first
embodiment, only the operation of different parts will be
explained.
When engine 8 is started, the intake pulsation generated in
conjunction with the intake operation of engine 8 is propagated via
intake manifold 28 and surge tank 26 into the air inside clean-side
intake duct 18 (see FIG. 2).
While engine 8 is running, as the amount of accelerator pedal
depression is increased, the airflow rate from air cleaner 22 to
surge tank 26 is increased (hereinafter to be referred to as the
acceleration mode). As a result, while the rotational velocity of
engine 8 is increased, the intake vacuum generated in the air
inside intake duct 10 rises (see FIG. 2).
When the engine is accelerating and the rotational velocity is R1,
the intake pulsation at the first frequency, among the plural
intake pulsations at different frequencies that form the intake
pulsation generated in conjunction with the intake operation of
engine 8, is propagated via connecting pipe 12 to the composite
membrane 16.
Because the frequency of the intake pulsation at the first
frequency matches first resonance frequency f1 of elastic membrane
30a, only elastic membrane 30a among elastic membranes 30a-30d
vibrates in the out-of-plane direction of composite membrane 16.
When elastic membrane 30a vibrates in the out-of-plane direction of
composite membrane 16, it causes pressure variations in the air in
additional pipe 14 on the side of composite membrane 16 that is
open to the external air, and these air pressure variations become
noise that is emitted to the external air side, such that the
suction noise is amplified.
When the amount of accelerator pedal depression is further
increased, that is, when the rotational velocity of the engine is
at R2, from among the plural intake pulsations at different
frequencies that form the intake pulsation in conjunction with the
intake operation of engine 8, the intake pulsation at the second
frequency is propagated via connecting pipe 12 to the composite
membrane 16 (elastic membrane).
Because the frequency of the intake pulsation at the second
frequency matches second resonance frequency f2 of elastic membrane
30b only elastic membrane 30b among elastic membranes 30a-30d
vibrates in the out-of-plane direction of composite membrane 16.
When elastic membrane 30b vibrates in the out-of-plane direction of
composite membrane 16, pressure variations result in the air in the
region between composite membrane 16 and the end of additional pipe
14 that is open to the external air, and air pressure variations
become noise that is emitted to the external air side, thereby
amplifying the suction noise.
When the amount of accelerator pedal depression is further
increased, that is, when the rotational velocity of the engine is
at R3, among the plural intake pulsations at different frequencies
that form the intake pulsation in conjunction with the intake
operation of engine 8, the intake pulsation at the third frequency
is propagated via connecting pipe 12 to composite membrane 16.
Because the frequency of the intake pulsation at the third
frequency matches third resonance frequency f3 of elastic membrane
30c, only elastic membrane 30c among elastic membranes 30a-30d
vibrates in the out-of-plane direction of composite membrane 16.
When elastic membrane 30c vibrates in the out-of-plane direction of
composite membrane 16, pressure variations result in the air in the
region between composite membrane 16 and the end of additional pipe
14 that is open to the external air, and said air pressure
variations become noise that is emitted to the external air side,
such that suction noise is amplified.
When the amount of accelerator pedal depression is further
increased, that is, when the rotational velocity of the engine is
at R4, among the plural intake pulsations at different frequencies
that form the intake pulsation in conjunction with the intake
operation of engine 8, the intake pulsation at the fourth frequency
is propagated via connecting pipe 12 to composite membrane 16
(elastic membrane member).
Because the frequency of the intake pulsation at the fourth
frequency matches fourth resonance frequency f4 of elastic membrane
30d, only elastic membrane 30d among elastic membranes 30a-30d
vibrates in the out-of-plane direction of composite membrane 16
(elastic membrane member). When elastic membrane 30d vibrates in
the out-of-plane direction of composite membrane 16, pressure
variations result in the air in the region between composite
membrane 16 and the end of additional pipe 14 that is open to the
external air, and the air pressure variations become noise that is
emitted to the external air side, thereby amplifying the suction
noise.
Consequently, in the acceleration mode, elastic membranes 30a-30d
with different resonance frequencies vibrate in the out-of-plane
direction of composite membrane 16 corresponding to the variation
in rotational velocity of engine 8. As a result, the suction noise
at the first frequency, the suction noise at the second frequency,
the suction noise at the third frequency and the suction noise at
the fourth frequency are amplified, and the amplified suction noise
is emitted to the external air side from the opening at the second
end of additional pipe 14 (see FIG. 2).
When the amplified suction noise is emitted to the external air
side from the second opening of additional pipe 14, the emitted
suction noise is propagated via the air into vehicle passenger
compartment 2, so that an impressive suction noise is transmitted
into vehicle passenger compartment 2 (see FIG. 1).
Variations of the Second Embodiments
Viewing device 1 that amplifies the suction noise in the second
embodiment, in the thickness direction of composite membrane 16, it
may be seen that composite membrane 16 is composed of four elastic
membranes 30a-30d. However, the second embodiment is not limited to
this scheme. That is, viewing in the thickness direction of
composite membrane 16, composite membrane 16 may be composed of
five or more elastic membranes. In this case, composite membrane 16
may work with frequencies over a wider range than composite
membrane 16 with just four elastic membranes 30a-30d as viewed in
the thickness direction of composite membrane 16.
Viewing the device 1 for amplifying suction noise in the second
embodiment in the thickness direction of composite membrane 16,
composite membrane 16 is comprised of four elastic membranes
30a-30d. Elastic membranes 30a-30d are formed with different areas,
and their resonance frequencies for vibration in the out-of-plane
direction of composite membrane 16 are different from each
other.
As a result, by selecting the different areas of elastic membranes
30a-30d according to resonance frequencies of vibration in the
out-of-plane direction of composite membrane 16, it is possible to
set the respective resonance frequencies of elastic membranes
30a-30d at the desired resonance frequencies.
Consequently, compared with the device for amplifying the suction
noise of a vehicle in the first embodiment, that is, the device for
amplifying the suction noise of a vehicle having three elastic
membranes as viewed in the thickness direction, it is possible to
further expand the frequency range where the suction noise can be
amplified, and it is possible to improve the sound quality of the
suction noise transmitted into vehicle passenger compartment 2.
Third Embodiment
Referring to FIGS. 8 and 9, a third embodiment will be explained.
FIGS. 8 and 9 are diagrams illustrating the structure of device 1
that amplifies suction noise in the third embodiment. FIG. 8 is a
diagram illustrating the structure of composite membrane 16, and
FIG. 9 is a cross section taken across X-Y in FIG. 8.
As shown in FIGS. 8 and 9, the structure of device 1 that amplifies
suction noise in the third embodiment is substantially the same as
that of the first embodiment except for the structure of composite
membrane 16. That is, the rigidity changing portion for composite
membrane 16 in the third embodiment, is formed of convex portions
40 formed on the surface of composite membrane 16 on the intake
duct side.
Viewed in the radial direction of composite membrane 16, convex
portions 40 are each generally V-shaped and project toward the
intake duct side when composite member 16 is installed in
connecting pipe 12. The thickness of composite membrane 16 where
convex portions 40 are formed is substantially equal to the
thickness of the remaining portions. That is, composite membrane 16
is formed with a generally uniform thickness throughout. Composite
membrane 16 with convex portions 40 formed thereon, may be formed
by integral molding using dies.
The remainder of the structure of device 1 is generally the same as
that of the first embodiment.
In the following, the operation of device 1 that amplifies the
suction noise in the third embodiment will now be explained.
Because the structure of everything besides composite membrane 16
is substantially the same as in the first embodiment, only the
operation of the different portions will be explained in
detail.
When engine 8 is started, the intake pulsation generated in
conjunction with the intake operation of engine 8 is propagated via
intake manifold 28 and surge tank 26 into the air inside clean-side
intake duct 18 (see FIG. 2).
While engine 8 is running, as the amount of accelerator pedal
depression is increased, the airflow rate from air cleaner 22 to
surge tank 26 is increased (hereinafter to be referred to as
acceleration mode). As a result, while the rotational velocity of
engine 8 is increased, the intake vacuum generated for the air in
intake duct 10 rises (see FIG. 2).
In the acceleration mode, when the amount of accelerator pedal
depression is changed, the rotational velocity of the engine is
changed. As a result, elastic membranes 30a-30c with different
resonance frequencies vibrate in the out-of-plane direction of
composite membrane 16 corresponding to the change in rotational
velocity of engine 8. As a result, pressure variations occur in the
air in the region between composite membrane 16 and the end of
additional pipe 14 that is open to the external air. The air
pressure variations are emitted as noise to the external air side,
so that the suction noise corresponding to the first frequency, the
suction noise corresponding to the second frequency, and the
suction noise corresponding to the third frequency are amplified
(see FIG. 2).
When the amplified suction noise is emitted to the external air
side from the opening at the second end of additional pipe 14, the
emitted suction noise is propagated via the air into vehicle
passenger compartment 2, so that an impressive suction noise is
transmitted into vehicle passenger compartment 2 (see FIG. 1).
Variations of the Third Embodiment
As viewed in the radial direction of composite membrane 16, device
1 that amplifies the suction noise in the third embodiment has
convex portions 40 formed on composite membrane 16, each being
V-shaped and projecting to the intake duct side, and the thickness
of composite membrane 16 is substantially uniform throughout when
the shape is formed. However, the third embodiment is not limited
to this scheme.
For example, as shown in FIG. 10A, a scheme may also be adopted in
which the thickness of the portions of composite membrane 16 where
convex portions 40 are positioned is thicker than the remaining
portions. Also, as shown in FIG. 10B, a scheme may also be adopted
in which convex portions 40 are each generally U-shaped as viewed
in the radial direction of composite membrane 16, and the thickness
of composite membrane 16 is substantially uniform throughout. In
addition, for example, as shown in FIG. 10C, a scheme may be
adopted in which convex portions 40 are each U-shaped projecting
toward the intake duct side as viewed in the radial direction of
composite membrane 16, and the thickness of composite membrane 16
where convex portions 40 are formed is thicker than the remaining
portions.
The rigidity changing portions in device 1 that amplifies suction
noise in the present embodiment consist of convex portions 40
formed on the surface of composite membrane 16 on the intake duct
side. The third embodiment is not limited to this scheme, however.
For example, as shown in FIGS. 11A and 11C, the rigidity changing
portions may also comprise generally concave portions 42 formed in
the surface of composite membrane (elastic membrane member) 16 on
the intake duct side. And, as shown in FIGS. 11B and 11D, a scheme
may also be adopted in which the rigidity changing portions
comprise generally convex portions 40 formed on the surface of
composite membrane 16 on the external air side.
The device 1 for amplifying the suction noise of a vehicle in the
third embodiment has rigidity changing portions that divide
composite membrane 16 into plural elastic membranes by convex or
concave portions 40, 42 formed on the surface of composite membrane
16 on the intake duct side. As a result, composite membrane 16 may
be formed with plural elastic membranes by means of a simple
structure.
As a result, it is possible to prevent increased manufacturing
costs for composite membrane 16, to prevent increased manufacturing
costs for the device 1 for amplifying the suction noise of a
vehicle, and to improve the producibility of the device for
amplifying the suction noise of a vehicle.
Fourth Embodiment
Referring to FIGS. 12 and 13, a fourth embodiment will be
explained. FIGS. 12 and 13 are diagrams illustrating the structure
of composite membrane 16 for device 1 that amplifies suction noise
in the fourth embodiment. FIG. 13 is a cross section of composite
member 16 taken across Y-Y in FIG. 12.
As shown in FIGS. 12 and 13, the structure of device 1 that
amplifies suction noise in the fourth embodiment is generally the
same as that of the first embodiment except for the structure of
composite membrane 16. That is, the rigidity changing portion of
composite membrane 16 in the fourth embodiment is formed of convex
portions 40 formed on the surface of composite membrane 16 on the
intake duct side, and each convex portion 40 has a core member
44.
Viewed in the radial direction of composite membrane 16, each
convex portion 40 is generally nV-shaped and projects toward the
intake duct side. The thickness of the portions of composite
membrane 16 where convex portions 40 are formed is substantially
equal to the thickness of the remaining portions. That is,
thickness of composite membrane 16 is substantially uniform
throughout.
Core member 44 is made of a wire material more rigid than composite
membrane 16, and it is arranged on the surface of composite
membrane 16 on the external air side.
The remainder of the structure of device 1 is generally the same as
that of the first embodiment 1.
In the following description, the operation of device 1 that
amplifies suction noise in the fourth embodiment will be explained.
Because the structure of everything besides composite membrane 16
is generally the same as in the first embodiment, only the
operation of the different portions will be explained in
detail.
When engine 8 is started, the intake pulsation generated in
conjunction with the intake operation of engine 8 is propagated via
intake manifold 28 and surge tank 26 into the air inside clean-side
intake duct 18 (see FIG. 2).
While engine 8 is running, as the amount of accelerator pedal
depression is increased, the airflow rate from air cleaner 22 to
surge tank 26 is increased (hereinafter to be referred to as
acceleration mode). As a result, while the rotational velocity of
engine 8 is increased, the intake vacuum generated in the air
inside intake duct 10 rises (see FIG. 2).
In the acceleration mode, when the amount of accelerator pedal
depression is changed, the rotational velocity of the engine is
changed. As a result, elastic membranes 30a-30c with different
resonance frequencies vibrate in the out-of-plane direction of
composite membrane 16 corresponding to changes in the rotational
velocity of engine 8. As a result, pressure variations develop in
the air in the region between composite membrane 16 and the end of
additional pipe 14 open to the external air. The air pressure
variations become noise emitted to the external air side, so that
the suction noise corresponding to the first frequency, the suction
noise corresponding to the second frequency, and the suction noise
corresponding to the third frequency are amplified, and the
amplified suction noise is emitted to the external air side from
the second opening of additional pipe 14 (see FIG. 2).
When the amplified suction noise is emitted to the external air
side from the second opening of additional pipe 14, the emitted
suction noise is propagated via the air into vehicle passenger
compartment 2, so that an impressive suction noise is transmitted
into vehicle passenger compartment 2 via dash panel 4 (see FIG.
1).
Variations of the Fourth Embodiment
Convex portions 40 formed on composite membrane 16 of device 1 that
amplifies the suction noise in the present embodiment are each
generally V-shaped and project to the intake duct side as viewed in
the radial direction of composite membrane 16. The thickness of
composite membrane 16 is substantially uniform throughout when the
shape is formed, and core member 44 is arranged on the surface of
composite membrane 16 on the external air side. However, the fourth
embodiment is not limited to this scheme. For example, as shown in
FIG. 14A, a scheme may also be adopted in which the thickness of
composite film 16 where convex portions 40 are set is greater than
in the remaining portions, with core member 44 being arranged
inside convex portions 40 set on composite membrane 16. Also, as
shown in FIG. 14B, a scheme may also be adopted in which each
convex portion 40 is generally U-shaped as viewed in the radial
direction of composite membrane 16. In addition, for example, as
shown in FIG. 14C, a scheme may also be adopted in which each
convex portion 40 of composite film 16 is generally U-shaped and
projects toward the intake duct side as viewed from the radial
direction of composite membrane 16, and the composite membrane 16
is formed thicker where convex portions 40 are set than in the
remaining portions, with core member 44 being arranged inside the
convex portions 40.
The rigidity changing portions of device 1 that amplifies suction
noise in the fourth embodiment comprise convex portions 40 formed
on the surface of composite membrane 16 on the intake duct side.
However, the fourth embodiment is not limited to this scheme. For
example, as shown in FIGS. 15A and 15C, the rigidity changing
portions can also comprise concave portions 42 formed on the
surface of the composite membrane 16 on the intake duct side, and
as shown in FIGS. 15B and 15D, a scheme may also be adopted in
which the rigidity changing portions consist of convex portions 40
formed on the surface of composite membrane 16 on the external air
side.
The device 1 for amplifying the suction noise of a vehicle in the
fourth embodiment has rigidity changing portions that divide
composite membrane 16 into plural elastic membranes by convex
portions 40 formed on the surface of the composite membrane on the
intake duct side, and the convex portions each have a core
member.
Thus composite membrane 16 may be formed with plural elastic
membranes with a simple structure, and at the same time, the
strength of the convex portions 40 may be increased.
As a result, it is possible to increase the producibility of the
device 1 for amplifying the suction noise of a vehicle, and at the
same time, the strength of composite membrane 16 may be increased
compared to that in the device for amplifying the suction noise of
a vehicle in the third embodiment, so that the durability of
composite membrane 16 may be improved.
Fifth Embodiment
Referring to FIG. 16, a fifth embodiment will be explained. FIG. 16
is a diagram illustrating the structure of composite member 16 of
device 1 that amplifies suction noise in the present
embodiment.
As shown in FIG. 16, the structure of device 1 that amplifies
suction noise in the fifth embodiment is substantially the same as
that of the first embodiment except for the structure of composite
membrane 16. That is, elastic membranes 30a-30c of composite
membrane 16 in the fifth embodiment are made of materials having
different modulus values. Here, the modulus refers to the property
representing resistance to deformation of the object per unit
volume. When the deformation and stress are proportional to each
other, the modulus is the proportionality coefficient, and it
depends on the material. Also, rigidity refers to the
proportionality coefficient between a bending and twisting force
applied to a structural body and the overall change in the
structural body. The factors determining rigidity include the
modulus of the material, the dimensions, and the shape of the
structure. For example, when a material with a higher modulus is
used, the rigidity is higher. When a single material is used, the
thicker the sheet, the higher the rigidity. Also, the rigidity
changes depending on the three-dimensional shape of the member that
is obtained by pressing processes.
The modulus of elastic membrane 30a is lower than the modulus of
elastic membrane 30b, and the modulus of elastic membrane 30b is
lower than the modulus of elastic membrane 30c. Consequently,
rigidity Ra of elastic membrane 30a is lower than rigidity Rb of
elastic membrane 30b, and rigidity Rb of elastic membrane 30b is
lower than rigidity Rc of elastic membrane 30c.
That is, the following relationship is established for elastic
membranes 30a-30c: Ra>Rb>Rc.
Here, because elastic membranes 30a-30c have different rigidities,
their resonance frequencies for vibration in the out-of-plane
direction of composite membrane 16 are different from each other.
Also, elastic membrane 30 with a higher rigidity has a lower
resonance frequency for vibration in the out-of-plane direction
than does elastic membrane 30 with a lower rigidity. Consequently,
for elastic membranes 30a-30c, assuming the resonance frequency of
elastic membrane 30a to be first resonance frequency f1, the
resonance frequency of elastic membrane 30b to be second resonance
frequency f2, and the resonance frequency of elastic membrane 30c
to be third resonance frequency f3, the relationship f1<f2<f3
is established.
In composite membrane 16 of the fifth embodiment, elastic membranes
30a-30c are made of materials having different modulus values. As a
result, the structure is divided into three elastic membranes
30a-30c without providing slots or other rigidity changing portions
on the intake duct side of composite membrane 16.
The remaining features of the structure of the device 1 are
substantially the same as those in the first embodiment.
In the following, the operation of device 1 that amplifies the
suction noise in the fifth embodiment will be explained. Because
the structure of everything besides composite membrane 16 is
substantially the same as that in the first embodiment, only the
operation of the different portions will be explained in
detail.
When engine 8 is started, the intake pulsation generated in
conjunction with the intake operation of engine 8 is propagated via
intake manifold 28 and surge tank 26 into the air inside clean-side
intake duct 18 (see FIG. 2).
While engine 8 is running, as the amount of accelerator pedal
depression is increased, the airflow rate from air cleaner 22 to
surge tank 26 is increased (hereinafter to be referred to as
acceleration mode). As a result, while the rotational velocity of
engine 8 is increased, the intake vacuum generated in the air
inside intake duct 10 rises (see FIG. 2).
In this case, because said elastic membranes 30a-30c have different
rigidity values, their resonance frequencies for vibration in the
out-of-plane direction of composite membrane 16 are different from
each other.
As a result, in the acceleration mode, as the amount of accelerator
pedal depression is changed, the rotational velocity of the engine
is changed. As a result, elastic membranes 30a-30c with different
resonance frequencies vibrate in the out-of-plane direction of
composite membrane 16 corresponding to changes in the rotational
velocity of engine 8.
As a result, the intake pulsation at the first frequency, the
intake pulsation at the second frequency and the intake pulsation
at the third frequency are amplified, and the amplified suction
noise is emitted to the external air side from additional pipe 14
(see FIG. 2).
When the amplified suction noise is emitted to the external air
side from the opening at the other end of additional pipe 14, the
emitted suction noise is propagated via the air into vehicle
passenger compartment 2, so that an impressive suction noise is
transmitted into vehicle passenger compartment 2 via dash panel 4
(see FIG. 1).
Variations of the Fifth Embodiment
In the fifth embodiment, elastic membranes 30a-30c of device 1 that
amplifies the suction noise have rigidities different from each
other, so that their resonance frequencies for vibration in the
out-of-plane direction of composite membrane 16 are different from
each other. However, the fifth embodiment is not limited to this
scheme. That is, a scheme may also be adopted in which elastic
membranes 30a-30c are made of materials having different mass
values, so that they have different resonance frequencies for
vibration in the out-of-plane direction of composite membrane 16.
Also, one may adopt a scheme in which elastic membranes 30a-30c are
made of materials different from each other with respect to their
modulus and/or mass, so that they have different resonance
frequencies for vibration in the out-of-plane direction of
composite membrane 16.
For composite membrane 16 in the fifth embodiment, elastic
membranes 30a-30c are made of materials having different modulus
values. As a result, the structure is provided with three divided
elastic membranes 30a-30c without setting slots or other rigidity
changing portions on the intake duct side of composite membrane 16.
However, the fifth embodiment is not limited to this scheme. For
example, a scheme may also be adopted in which composite membrane
16 is composed of three separated elastic membranes 30a-30c by
forming slots or other rigidity changing portions on the surface of
composite membrane (elastic membrane member) 16 on the intake duct
side, just as in any of the previous embodiments.
Viewed in the thickness direction of composite membrane 16,
composite membrane 16 of the device 1 for amplifying the suction
noise of a vehicle in the fifth embodiment is composed of three
elastic membranes. Because the elastic membranes have different
rigidity values, their resonance frequencies for vibration in the
out-of-plane direction of composite membrane 16 are different from
each other.
As a result, in the acceleration mode, the various elastic
membranes vibrate in the out-of-plane direction of composite
membrane 16 corresponding to changes in the rotational velocity of
engine 8.
Consequently, the intake pulsation at the first frequency, the
intake pulsation at the second frequency and the intake pulsation
at the third frequency are amplified corresponding to changes in
the rotational velocity of engine 8, and the amplified suction
noise is emitted to the external air side from the second opening
of the additional pipe. The emitted suction noise is propagated via
dash panel 4 into vehicle passenger compartment 2, and an
impressive suction noise is transmitted into vehicle passenger
compartment 2.
As a result, it is possible to generate plural resonance
frequencies with a single composite membrane 16, and an impressive
suction noise may be generated without the need of plural intake
ducts. Also, because the structure does not need plural intake
ducts, the freedom of layout design may be improved, and device 1
may be adopted for vehicles with different body sizes or different
structures.
Also, as viewed in the thickness direction, composite membrane 16
of the device 1 for amplifying suction noise in the fifth
embodiment is composed of three elastic membranes, and these
elastic membranes are made of materials with different modulus
values, so that they have different frequencies for vibration in
the out-of-plane direction of composite membrane 16.
Consequently, by selecting the modulus values of the elastic
membranes corresponding to the respective resonance frequencies for
vibration in the out-of-plane direction of composite membrane 16,
it is possible to set the resonance frequencies of the elastic
membranes at the respective desired resonance frequencies.
As a result, it is possible to set the resonance frequencies of the
various elastic membranes for vibration in the out-of-plane
direction of composite membrane 16 at plural desired frequencies,
and it is possible to expand the range of frequency bands where
amplification of the suction noise may be realized. As a result, it
is possible to improve the sound quality of the suction noise
transmitted into vehicle passenger compartment 2.
Also, because composite membrane 16 in the device 1 for amplifying
the suction noise of a vehicle in the fifth embodiment has elastic
membranes made of materials having different modulus values,
composite membrane 16 is constituted as three separated elastic
membranes without the provision of slots or other rigidity changing
portions on the surface of composite membrane 16 on the intake duct
side.
Consequently, the durability of composite membrane 16 is improved
due to the lack of rigidity changing portions with thicknesses
different from other portions set at the boundaries between
adjacent elastic membranes of composite membrane 16.
The preceding description has been presented only to illustrate and
describe exemplary embodiments of the oil return device according
to the claimed invention. It is not intended to be exhaustive or to
limit the invention to any precise form disclosed. It will be
understood by those skilled in the art that various changes may be
made and equivalents may be substituted for elements thereof
without departing from the scope of the invention. In addition,
many modifications may be made to adapt a particular situation or
material to the teachings of the invention without departing from
the essential scope. Therefore, it is intended that the invention
not be limited to the particular embodiment disclosed as the best
mode contemplated for carrying out this invention, but that the
invention will include all embodiments falling within the scope of
the claims. The invention may be practiced otherwise than is
specifically explained and illustrated without departing from its
spirit or scope. The scope of the invention is limited solely by
the following claims.
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