close

Вход

Забыли?

вход по аккаунту

?

DESCRIPTION JP2016027730

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2016027730
An object of the present invention is to sufficiently reduce abnormal noise emitted from a bass
reflex port of a speaker device. A bass reflex port (30) is a tubular body having side end portions
(342, 344) located on both sides of an intermediate portion (32), and allows communication
between the inside and the outside of a housing of a speaker device. The inner circumferential
area surrounded by the inner circumferential surface 42 of the side end is a noncircular shape
that is five-fold symmetric about the central axis X, and the area of the inner circumferential area
is from the proximal end to the distal end of the side end To increase. The ridges and valleys of
the inner circumferential surface 42 extend in a spiral shape. [Selected figure] Figure 10
Bass reflex port, speaker device and tube
[0001]
The present invention relates to a tube through which air flows, and in particular to a tube
structure suitable for a bass reflex port of a speaker device.
[0002]
BACKGROUND ART Conventionally, bass reflex type speaker devices have been proposed that
use the sound radiated from the speaker unit to the rear side to increase the volume of the bass
range.
In the bass reflex type speaker device, a bass reflex port for connecting the inside and the outside
16-04-2019
1
of the enclosure is provided. For example, Patent Document 1 discloses a speaker device aiming
to reduce abnormal noise by forming the vicinity of an end portion of a bass reflex port in a flare
shape (a shape in which an inner diameter increases as approaching a tip portion).
[0003]
JP, 2008-048176, A
[0004]
However, it is actually difficult to sufficiently reduce the abnormal noise emitted through the
bass reflex port only by the configuration in which the vicinity of the end of the bass reflex port
has a simple flare shape.
For example, when the volume of the reproduced sound is large, the listener may perceive
abnormal noise originating from the bass reflex port. In consideration of the above
circumstances, the present invention aims to reduce noise emitted from a pipe body such as a
bass reflex port.
[0005]
In order to solve the above problems, the bass reflex port according to the present invention is a
tubular bass reflex port through which air flows, and it passes through one feature point on the
inner circumference in the first cross section perpendicular to the central axis. The first inner
diameter line perpendicular to the central axis and the first cross section pass through the
feature points corresponding to one feature point on the inner periphery of the second cross
section different in position on the central axis and pass the central axis The angle with the
reference plane including the central axis is different between the orthogonal second inner
diameter lines. In the above configuration, since the angle of the inner diameter line passing
through the feature point on the inner periphery and orthogonal to the central axis is different
between the first cross section and the second cross section, the angle of the inner diameter line
is at the position of the cross section The symmetry of the vortex ring generated inside the bass
reflex port is reduced as compared with the configuration which is maintained constant
regardless of that. Therefore, it is possible to reduce the noise emitted from the bass reflex port.
Note that a typical example of the feature point on the inner circumference is, for example, an
extreme value point (maximum point of the inner diameter or minimum point of the inner
16-04-2019
2
diameter) where the inner diameter is an extreme value. It is also possible to use feature points.
Further, the feature points on the inner circumference in the first cross section and the feature
points on the inner circumference in the second cross section “correspond” to each other
means the figure defined by the inner circumference in the first cross section. It means that the
positional relationship of the feature points on the circumference and the positional relationship
of the feature points on the inner periphery with respect to the figure defined by the inner
periphery in the second cross section are similar to each other.
[0006]
In a preferred aspect of the present invention, an angle of the inner diameter line passing
through one feature point on the inner periphery in a cross section perpendicular to the central
axis and orthogonal to the central axis is the angle of the cross section on the central axis Change
continuously with movement. In the above configuration, since the angle of the inner diameter
line changes continuously with respect to the movement of the cross section, the abnormal noise
radiated from the bass reflex port is reduced and the angle of the inner diameter line changes
discontinuously as compared with the configuration It is possible to improve the aesthetic
appearance of the bass reflex port. The section in which the angle of the inner diameter line
changes does not have to extend over the entire length of the bass reflex port. For example, a
configuration in which the angle of the inner diameter line is continuously varied only in a
specific portion of the bass reflex port may be employed. In a particularly preferred manner, the
inner diameter line rotates continuously in one direction for the movement of the cross section
on the central axis. That is, in the bass reflex port according to the present invention, the
characteristic point on the inner periphery in the cross section perpendicular to the central axis
is configured such that the locus connecting the respective cross sections having different
positions on the central axis has a spiral shape. It can be said in another way.
[0007]
In a preferred embodiment of the present invention, the rotation angle of the inner diameter line
for the movement of the unit volume of the cross section is different depending on the position
on the central axis. For example, the rotation angle of the inner diameter line with respect to the
movement of the unit amount of the cross section is larger on the tip side of the bass reflex port
than on the center side. According to the above configuration, it is possible to reduce abnormal
noise radiated from the bass reflex port and to improve the aesthetic appearance of the bass
reflex port.
16-04-2019
3
[0008]
In a preferred embodiment of the present invention, the cross-sectional area in the pipe (for
example, the area of the inner circumferential region Q) increases toward the tip of the bass
reflex port. That is, for example, a flare shape is added. It is possible to enhance the noise
suppression effect as compared with the configuration in which the cross-sectional area in the
pipe is equal at each position on the central axis.
[0009]
In a preferred embodiment of the present invention, a first locus (for example, maximum point
PA) on the inner periphery of a cross section perpendicular to the central axis is mutually
connected for each cross section, and on the inner periphery of the cross section The shape is
different from the second locus in which the second feature points (for example, the minimum
points PB) different from the first feature points are mutually connected in each cross section.
According to the above configuration, since the shapes of the first locus of the first feature point
and the second locus of the second feature point are different, the effect of reducing noise
emitted from the bass reflex port is particularly remarkable. is there.
[0010]
In a preferred embodiment of the present invention, the inner diameter in the cross section
perpendicular to the central axis changes continuously along the circumferential direction of the
central axis. For example, the inner circumferential area surrounded by the inner circumferential
surface in a cross section perpendicular to the central axis is non-circular with rotational
symmetry. According to the above configuration, compared with the configuration in which the
inner peripheral region of the bass reflex port is a perfect circle, it is possible to disperse the area
where the turbulence of the air flow is large in the bass reflex port in a wide range on the central
axis. . Therefore, the effect of reducing noise emitted from the bass reflex port is particularly
remarkable.
[0011]
16-04-2019
4
A speaker device according to the present invention includes a housing, a speaker unit fixed to
the housing, and the bass reflex port of each of the above-described modes for communicating
the inside and the outside of the housing. According to the above configuration, it is possible to
reduce abnormal noise emitted from the bass reflex port.
[0012]
Further, the present invention is also specified as a tube having the same structure as the bass
reflex port of each of the above-described embodiments. A tube according to the present
invention is a tube through which air flows, and a first inner diameter line passing through one
feature point on the inner periphery in a first cross section perpendicular to the central axis and
orthogonal to the central axis; The second cross-sectional area is the center axis of the second
cross section perpendicular to the central axis, passing through the feature point corresponding
to one feature point on the inner periphery of the second cross section different in position on
the central axis from the first cross section. The angles with respect to the reference plane
including. In addition, the use of the pipe body which concerns on this invention is arbitrary.
[0013]
It is a sectional view of a speaker device concerning a 1st embodiment of the present invention. It
is a perspective view and a cutaway view of a bass reflex port. It is a front view of a bass reflex
port. It is a longitudinal cross-sectional view of a bass reflex port. It is explanatory drawing of the
abnormal noise which generate | occur | produces from a bass reflex port. It is a distribution map
of the light hill volume in the inside of the existing port, and the circumference. It is explanatory
drawing of the principle by which abnormal noise is reduced in 1st Embodiment. It is a frequency
characteristic of reproduction sound by a plurality of types of bass reflex ports. It is a graph
which shows the level of the abnormal sound by each bass reflex port. It is a perspective view
and a cutaway view of a bass reflex port in a 2nd embodiment. It is a front view of the bass reflex
port in a 2nd embodiment. It is explanatory drawing of the shape of an inner peripheral area |
region. It is explanatory drawing of the inner peripheral area | region in each cross section. It is a
graph which shows the relationship between the shape of a bass reflex port, and the level of
noise. It is a schematic diagram of the other shape of an inner peripheral area | region. It is a
graph which shows the relationship between the order of rotation object of an inner periphery
area | region, and the level of noise. It is a schematic diagram of the other shape of an inner
peripheral area | region. It is a graph which shows the relationship between each shape
illustrated in FIG. 17 and the level of noise.
16-04-2019
5
[0014]
First Embodiment FIG. 1 is a cross-sectional view of a speaker device 100 according to a first
embodiment of the present invention. As shown in FIG. 1, the speaker device 100 according to
the first embodiment includes a housing (enclosure) 10, a speaker unit 20, and a bass reflex port
30A, and responds to acoustic signals supplied from an external device (not shown). Sound
device that radiates the
[0015]
The housing 10 is a hollow structure (typically, a rectangular solid) formed of a plurality of plate
members. A substantially circular opening 14 and an opening 16 are formed in the plate member
12 located on the front side of the housing 10. The speaker unit 20 is fixed to the inside of the
opening 14. That is, the plate 12 of the housing 10 functions as a baffle plate. The speaker unit
20 is a sound emitting body that radiates a sound according to an acoustic signal by vibrating a
diaphragm according to an acoustic signal supplied from an external device (for example, a signal
processing device such as an amplifier). Although the height and bandwidth of the reproduction
band of the speaker unit 20 are arbitrary, the present invention is particularly suitable for a
configuration using the speaker unit 20 (for example, a subwoofer) having the bass band as the
reproduction band.
[0016]
The bass reflex port (duct) 30 </ b> A is a substantially cylindrical tube which is installed inside
the housing 10 and causes the inside and the outside of the housing 10 to communicate, and is
radiated from the speaker unit 20 to the back side of the housing 10 Among the sounds, the
sound component in the low range is enhanced by resonance (Helmholtz resonance) and emitted.
That is, the housing 10 and the bass reflex port 30A constitute a Helmholtz resonator whose
resonance frequency is a frequency near the lower limit frequency of the sound radiated from
the speaker unit 20 to the front side.
[0017]
16-04-2019
6
FIG. 2 is a perspective view and a cutaway view of the bass reflex port 30A. In the cutaway view
of FIG. 2, a state in which the bass reflex port 30A is cut along a plane including the central axis
(tube axis) X (hereinafter referred to as “longitudinal section”) is illustrated. As shown in FIGS.
1 and 2, the bass reflex port 30A is divided along the central axis X into an intermediate portion
32, a side end 342 and a side end 344. The side end 342 is positioned on one end side (end on
the front side) of the middle portion 32, and the side end 344 is positioned on the other end side
(rear end) on the middle portion 32. As shown in FIG. 1, an end (hereinafter referred to as
“tip”) of the side end 342 opposite to the middle portion 32 is connected to the inner
peripheral edge of the opening 16 of the plate 12 on the front side of the housing 10. The inner
circumferential surface (inner wall surface) 42 of the side end portion 342 and the front surface
of the plate 12 are continuous. On the other hand, the tip of the side end 344 opposite to the
middle portion 32 is located inside the housing 10. That is, the bass reflex port 30 </ b> A
protrudes on the back side of the plate 12 so that the central axis X is substantially orthogonal to
the plate 12. Incidentally, the division of the middle portion 32, the side end 342 and the side
end 344 is a convenient division focusing on the structure of the bass reflex port 30A, and in
practice, the bass reflex port 30A is integrally formed by a manufacturing technique such as
injection molding. Configured However, it is also possible to separately manufacture the
intermediate portion 32, the side end 342 and the side end 344 and connect them to each other.
The side end 342 and the side end 344 in the first embodiment have the same shape. Therefore,
in the following description, the side end portion 342 and the side end portion 344 are
comprehensively expressed as the side end portion 34, and the individual description thereof is
appropriately omitted. However, it is also possible to make the shape different between the side
end 342 and the side end 344.
[0018]
FIG. 3 is a front view of the bass reflex port 30A when the tip end of the side end 34 is observed
from the direction of the central axis X (that is, the longitudinal direction of the bass reflex port
30A). As understood from FIGS. 2 and 3, the middle portion 32 has a circular cross-sectional
shape in a cross section perpendicular to the central axis X (hereinafter referred to as “cross
section”) and has an inner diameter and an outer diameter of the central axis X. It is a straight
tubular portion maintained substantially constant at each upper position. On the other hand, in
the lateral end 34 (342, 344), the area of a region Q (hereinafter referred to as “inner
circumferential region”) surrounded by the inner circumferential surface 42 in the cross section
perpendicular to the central axis X is on the intermediate portion 32 side. It forms in the flare
shape which increases continuously from an edge part (henceforth a "base edge part") to a tip
part. The inner circumferential region Q corresponds to a cross section (a cross section in the
tube) of the flow path of air in the bass reflex port 30A.
16-04-2019
7
[0019]
As shown in FIGS. 2 and 3, the inner circumferential region Q of the side end portion 34 is noncircular having rotational symmetry (N-fold symmetry) about the central axis X (N is a natural
number of 2 or more) , Funnel-shaped corolla (petals of convolvulus etc.). In the first
embodiment, the case where the inner circumferential region Q of the side end portion 34 is a
five-fold symmetric (N = 5) closed curve is illustrated. As can be understood from FIGS. 2 and 3,
the shape of the inner circumferential region Q is such that the noncircular shape of five-fold
symmetry gradually approaches circular from the distal end to the proximal end of the side end
34 and is circular at the proximal end. And continues to the circular inner circumferential region
Q of the intermediate portion 32. That is, the inner circumferential area Q in each cross section
on the central axis X has a corresponding shape.
[0020]
As shown in FIG. 3, the distance between any one point on the line of intersection between the
cross section and the inner circumferential surface 42 (that is, the outline of the inner
circumferential area Q) and the central axis X is the inner diameter Φ of the side end 34 and the
distance When defined, the inner circumferential region Q of the side end portion 34 can also be
expressed as a shape in which the inner diameter Φ changes in the circumferential direction
around the central axis X. Specifically, the inner diameter Φ increases and decreases periodically
and continuously with a unit (period) of 72 ° (360 ° / N) around the central axis X. Therefore,
on the contour line of the inner circumferential region Q, there are five (N) maximum points PA
at which the inner diameter 極大 is a maximum and the same number of minimum points PB at
which the inner diameter 極小 is a minimum. The maximum points PA and the minimum points
PB are alternately arranged in the circumferential direction every 36 ° (360 ° / 2N). As
understood from FIG. 3, the maximum point PA corresponds to the bottom point of the valley of
the inner circumferential surface 42, and the minimum point PB corresponds to the top of the
peak of the inner circumferential surface 42. Therefore, the contour line of the inner
circumferential region Q can also be described as a closed curve in which five peaks and five
valleys are alternately arranged in the circumferential direction. As understood from the above
description, the inner circumferential region Q of the first embodiment has a shape in which the
curvature is repeatedly increased and decreased in the circumferential direction around the
central axis X. Specifically, the curvature of the contour line of the inner circumferential region Q
repeatedly changes from one of positive and negative numbers to the other along the
circumferential direction. That is, in the inner circumferential area Q, a range in which the center
of curvature is located inside the inner circumferential area Q and a range in which the center of
16-04-2019
8
curvature is located outside the inner circumferential area Q alternate alternately along the
circumferential direction.
[0021]
FIG. 4 is a cross-sectional view of the side end 34 in the vertical cross section V0 of FIG. 3. The
longitudinal cross section V0 passes through both the maximum point PA and the minimum
point PB. Therefore, a locus RA connecting the maximum points PA of the inner circumferential
area Q over a plurality of cross sections on the central axis X, and a locus RB connecting the
minimum points PB of the inner circumferential area Q over a plurality of transverse sections on
the central axis X And exist in the longitudinal cross section V0. Trajectory RA corresponds to a
line of intersection of longitudinal cross section V0 and inner circumferential surface 42, and
locus RB corresponds to a line of intersection of longitudinal cross section V0 and inner
circumferential surface 42. Each of the locus RA and the locus RB is a curve in which the distance
(inner diameter Φ) with the central axis X continuously increases from the proximal end to the
distal end of the side end 34.
[0022]
As described above, the inner circumferential region Q of the side end portion 34 is non-circular
in which the inner diameter Φ changes in the circumferential direction around the central axis X.
Therefore, the shapes of the trajectory RA and the trajectory RB are different. For example, as
shown in FIG. 4, when the shape (flare shape) of the inner peripheral surface 42 of the side end
34 is defined so that each of the locus RA and the locus RB is an arc of an ellipse, the ellipticity of
the ellipse The relative ratio of the diameters is different between the locus RA and the locus RB.
Specifically, the locus RA is an arc of an ellipse EA of a major axis LA1 and a minor axis LA2, and
a locus RB is an arc of an ellipse EB of a major axis LB1 and a minor axis LB2. The minor axis
LA2 of the ellipse EA defining the locus RA exceeds the minor axis LB2 of the ellipse EB of the
locus RB (LA2> LB2), and the major axis LA1 of the ellipse EA of the locus RA is equal to the
major axis LB1 of the ellipse EB of the locus RB. (LA1 = LB1). Therefore, the ellipticity (LA2 /
LA1) of the ellipse EA of the trajectory RA exceeds the ellipticity (LB2 / LB1) of the ellipse EB of
the trajectory RB. That is, the curvature of the trajectory RA (the average value over the entire
length of the trajectory RA) exceeds the curvature of the trajectory RB. Also, it can be said that
the total length of the trajectory RA exceeds the total length of the trajectory RB. As understood
from the above description, the inner circumferential surface 42 of the side end portion 34 in the
first embodiment has a plurality of cross sections including feature points such as the maximum
point PA and the minimum point PB in the contour line of the inner circumferential region Q. In
16-04-2019
9
other words, the shape of the trajectory R (RA, RB) connected across may be repetitively changed
in the circumferential direction about the central axis X.
[0023]
The shape described above is adopted for the inner circumferential surface 42 of the side end 34
in order to reduce noise generated from the bass reflex port 30A. Therefore, the abnormal noise
generated from the bass reflex port will be described in detail below. FIG. 5 shows the frequency
characteristic of an acoustic signal (broken line) and the frequency characteristic of reproduced
sound (solid line) when an acoustic signal of a pure tone (for example, a sine wave of 30 Hz)
having a frequency equal to the Helmholtz resonance frequency is supplied to an existing
speaker device. Is a graph showing the relationship with In the case of reproducing a frequency
close to the Helmholtz resonance frequency, if the flow velocity of air flowing inside the bass
reflex port is high, the airflow is disturbed inside the bass reflex port or in the vicinity of the tip,
and a vortex ring is generated. The vortex ring contains a frequency component over a wide band
whose main component is the Helmholtz resonance frequency. Then, among the frequency
components included in the vortex ring, a component (dotted line portion in FIG. 5) that matches
or approximates the resonance frequency of the bass reflex port or the casing is enhanced by
resonance, and is perceived as abnormal noise by the listener.
[0024]
In consideration of the above phenomenon, the inventor of the present application infers that the
vortex ring (turbulence) of the air flow circulating inside the bass reflex port is the cause of the
abnormal noise, and the inner circumference over the entire section in the direction of the
central axis X The turbulence of the internal air flow was simulated for an existing bass reflex
port (hereinafter referred to as "pre-existing port") whose area is circular. Part (A) of FIG. 6 is an
analysis result of the existing port I, and part (B) of FIG. 6 is an analysis result of the existing port
II. The existing port I and the existing port II are bass reflex ports to which a flare shape is added.
Specifically, the existing port I is a sample adopting an arc of an ellipse having a major axis of
144 mm and a minor axis of 48 mm as the inner circumferential surface in the longitudinal cross
section, and the existing port II has a major axis of 230 mm and a minor axis of 48 mm Is a
sample in which the arc of the ellipse of is adopted as the inner circumferential surface in the
longitudinal section. That is, the ellipticity (the relative ratio of the minor axis to the major axis)
of the inner peripheral surface of the existing port I exceeds the ellipticity of the inner peripheral
surface of the existing port II. When an acoustic signal having a frequency equivalent to the
Helmholtz resonance frequency is supplied to a speaker apparatus adopting each of the existing
16-04-2019
10
port I and the existing port II, the abnormal sound perceived from the reproduced sound is the
existing port I of the existing port II. A tendency was observed that was remarkable as compared
with.
[0025]
Parts (A) and (B) of FIG. 6 illustrate the distribution of Lighthill Volumes inside and near existing
ports. The light hill volume is an index for evaluating the degree of air flow turbulence
(turbulence), and in FIG. 6, the higher the light hill volume (the higher the air flow turbulence
area), the higher the gradation (higher). It is expressed in gradation close to white. Comparing
part (A) and part (B) in FIG. 6, in the existing port II (part (B) in FIG. 6) where noise is large, the
area where the turbulence of the air flow is large is in the narrow area near the tip. In the
existing port I (part (A) in FIG. 6) where noise is localized while small, it is possible to confirm
that the region where the turbulence of the air flow is large is distributed in a wide region around
the tip. From the above tendency, the inventors of the present invention speculated that the
abnormal noise from the bass reflex port can be suppressed if the region where the turbulence of
the air flow is large can be dispersed in a wide range along the central axis X of the bass reflex
port. The bass reflex port 30A of the first embodiment described with reference to FIGS. 1 to 4 is
a preferred example of a shape adopted based on the above findings.
[0026]
A portion (A) of FIG. 7 is an explanatory view of a region where the disturbance of the air flow is
large in the existing port whose inner peripheral surface has a circular flare shape, and the
portion (B) of FIG. 7 is a bass reflex of the first embodiment. It is explanatory drawing of the area
| region where disturbance of the airflow in port 30A is large. As understood from part (A) of FIG.
7, in the existing port in which the inner circumferential area is maintained circularly over the
entire section, the area where the turbulence of the air flow is large is within the narrow area on
the central axis X. It occurs over 42 rounds. That is, a true circular vortex ring is generated inside
the existing port. On the other hand, in the bass reflex port 30A of the first embodiment, the
shapes of the inner circumferential surface 42 (trajectory RA, locus RB) in the longitudinal cross
section are different at each circumferential position, and thus occur inside the bass reflex port
30A. The vortex ring has a meandering shape along the circumferential direction. That is, the
area where the turbulence of the air flow is large is dispersed in a wide area on the central axis X.
As described above, the region where the turbulence of the air flow is large is dispersed in the
direction of the central axis X. As a result, according to the first embodiment, abnormal noise
caused by the bass reflex port 30A is reduced.
16-04-2019
11
[0027]
FIG. 8 shows the frequency characteristics of the reproduced sound in each of a plurality of cases
where the shapes of the bass reflex port are different, and FIG. 9 shows the sound pressure in the
band B of FIG. 8 perceived as abnormal noise by the listener (different FIG. 6 is a graph in which
sound levels are shown for each of a plurality of bass reflex ports. The existing port III in FIGS. 8
and 9 is a straight-tube type (shape in which a flare shape is not given). According to the first
embodiment in which the shape (trajectory R) of the inner circumferential surface 42 in the
longitudinal section is made different at each position in the circumferential direction, abnormal
noise is surely suppressed as compared with the comparative example from FIG. You can also
check. Further, according to the configuration in which the inner circumferential area Q is noncircular with rotational symmetry as in the first embodiment, the aesthetic appearance
(designability) is compared with the existing port in which the inner circumferential area is
simply circular. There is also an advantage of being excellent in
[0028]
Second Embodiment The second embodiment of the present invention will be described below. In
addition, about the element in which an effect | action and a function are the same as 1st
Embodiment in each form illustrated below, the code | symbol referred by description of 1st
Embodiment is diverted and detailed description of each is abbreviate | omitted suitably.
[0029]
FIG. 10 is a perspective view and a cut view (a cut view in a longitudinal cross section) of the
bass reflex port 30B according to the second embodiment, and FIG. 11 is a side view of the side
end 34 (342, 344) from the direction of the central axis X. It is a front view of the bass reflex
port 30 at the time of observing a tip part. As can be understood from FIGS. 10 and 11, the bass
reflex port 30B of the second embodiment has a shape (i.e., an inner circumferential area Q of
the same shape as that of the first embodiment rotated according to the position on the central
axis X) , A shape in which the inner circumferential surface 42 is twisted around the central axis
X). That is, the ridges and valleys of the inner circumferential surface 42 of the bass reflex port
30B extend in a spiral shape along the central axis X.
16-04-2019
12
[0030]
FIG. 12 is a schematic view of a plurality of cross sections C (C1 to C5) at different positions on
the central axis X, and FIG. 13 is a schematic view of the inner circumferential area Q for each
cross section C in FIG. . The cross section C1 to the cross section C5 in FIG. 12 are arranged in
order from the distal end (opposite to the middle portion 32) of the side end 34 to the proximal
end. For example, the cross section C1 is located on the distal end side of the side end 34, and
the cross section C5 is located on the proximal end side. The shape of the inner circumferential
area Q in any one cross section C is the same as that of the first embodiment. That is, the inner
circumferential region Q of the side end portion 34 is set to a rotationally symmetric non-circular
shape in which the inner diameter Φ changes along the circumferential direction around the
central axis X. Therefore, also in the second embodiment, the same effect as that of the first
embodiment is realized. Although the area (inner diameter)) of the inner circumferential area Q
of the side end 34 increases from the proximal end to the distal end as in the first embodiment
(flare shape), in FIG. 12 and FIG. Changes in the area of are omitted for convenience.
[0031]
As shown in FIG. 13, a straight line passing through any one maximum point PA on the inner
circumferential surface 42 in the cross section C perpendicular to the central axis X and
orthogonal to the central axis X (hereinafter referred to as “inner diameter line”) Assume L.
That is, the inner diameter line L is a straight line extending in the radial direction from the
central axis X and passing through the maximum point PA. As shown in FIG. 13, assuming a
specific vertical cross section (hereinafter referred to as “reference plane”) VREF including
central axis X, the angle θ of inner diameter line L with respect to reference plane VREF is the
cross section C on central axis X It changes continuously according to the position. Specifically,
the inner diameter line L continuously rotates in one direction with respect to movement in one
direction of the cross section C on the central axis X (for example, movement from the tip side to
the base side). That is, as shown in FIG. 13, for example, the angle θ of the inner diameter line L
in the cross section C2 exceeds the angle θ of the inner diameter line L in the cross section C1,
and the angle θ of the inner diameter line L in the cross section C3 is the cross section It
exceeds the angle θ of the inner diameter line L in C2. Therefore, as can be understood from
FIG. 12, a locus RA connecting mutually corresponding maximum points PA (black circles in FIG.
12) in each cross section C with respect to a plurality of cross sections C1 to C5 is a central axis
X It becomes a spiral shape which rotates around the central axis X along. Similarly, a locus RB in
which the local minimum points PB (white circles in FIG. 12) in each cross section C are
connected to one another for a plurality of cross sections C1 to C5 is also in a spiral shape. That
16-04-2019
13
is, as described above, the valley portion (locus RA of the maximum point PA) and the peak
portion (locus RB of the minimum point PB) of the inner circumferential surface 42 spiral around
the central axis X along the central axis X To extend. In the second embodiment, as in the first
embodiment, the inner circumferential surface 42 of the side end 34 has a flare shape, and the
inner circumferential region Q has a non-circular shape of rotational symmetry. Therefore, the
shape (curvature or total length) of the locus RA of the maximum point PA and the locus RB of
the minimum point PB are different. Specifically, the total length of the trajectory RA exceeds the
total length of the trajectory RB.
[0032]
As shown in FIG. 11, the inner diameter line L rotates by an angle η from the proximal end to
the distal end (that is, the entire region between the ends of the side end 34) of the side end 34.
The angle η is set to any appropriate numerical value. However, for example, when forming the
bass reflex port by injection molding, if the angle 取出 is large, it becomes difficult to take out the
mold, so the angle (for example, 20 °) under which the mold for injection molding can be
reliably extracted An angle η within the range is preferred. For example, a configuration in
which the angle η is set to 18 ° (360 ° / 4N) is preferable. On the other hand, if the angle η is
excessively large, turbulence (turbulence) of the air flow is likely to occur in the vicinity of the
inner circumferential surface 42. Therefore, the angle η is appropriately selected, for example,
within a range in which the generation of abnormal noise due to turbulence is not perceived.
Specifically, the upper limit value of the angle η is appropriately selected in consideration of
various factors (for example, the flow velocity assumed to the air in the bass reflex port 30B and
the like) which affect the turbulent flow of air.
[0033]
Further, the rotation angle (hereinafter referred to as “unit angle”) of the inner diameter line L
when the cross section C moves by a predetermined unit amount along the central axis X differs
depending on the position of the cross section C on the central axis X Do. Specifically, of the side
end portions 34, the tip end side (the opposite side to the middle portion 32) of the bass reflex
port 30B is larger in unit angle than the center side (the middle portion 32 side). That is, the unit
angle increases toward the tip end of the side end 34. Therefore, as shown in FIG. 11, a locus RA
observed when the tip of the side end 34 is observed from the direction of the central axis X
(front direction of the bass reflex port 30) (ie, projection perpendicular to the central axis X The
projection image of the trajectory RA with respect to the surface is a curve with a predetermined
curvature ρ. The curvature ρ is set to, for example, a numerical value of about 1/50 [1 / mm]
16-04-2019
14
(curvature radius: 50 mm).
[0034]
As described with reference to FIG. 7 in the first embodiment, in the existing port in which the
inner circumferential area Q is circular, the generation of a circular circular vortex ring in the
inner side notices abnormal noise remarkably. On the other hand, in the first embodiment,
abnormal noise is reduced by meandering the vortex ring inside the bass reflex port 30A in the
circumferential direction (dispersing a region where the turbulence of the air flow is large in a
wide range in the direction of the central axis X) . As can be inferred from the above tendency, as
the geometric symmetry of the vortex ring around the central axis X decreases, the abnormal
noise is reduced. In the second embodiment, in the inner peripheral surface 42 of the side end
34, the valley (locus RA of the maximum point PA) and the peak (locus RB of the minimum point
PB) of the inner peripheral surface 42 are spiral. Since the shape is selected, the geometric
symmetry of the vortex ring inside the bass reflex port 30B is reduced compared to the existing
port as well as the first embodiment. Therefore, according to the second embodiment, it is
possible to suppress abnormal noise more than the first embodiment. In FIG. 8 and FIG. 9
described above, the level of abnormal noise observed when the bass reflex port 30B according
to the second embodiment is adopted is also described. It can also be confirmed from FIGS. 8 and
9 that the noise reduction effect according to the second embodiment exceeds that of the first
embodiment. Further, according to the configuration in which the ridges and valleys of the inner
circumferential surface 42 are formed in a spiral shape as in the second embodiment, the
existing port whose inner circumferential region is a simple round shape and the inner diameter
line L do not rotate There is also an advantage of being superior in design aesthetics
(designability) as compared with the first embodiment.
[0035]
<Specific Shape of Bass Reflex Port> The preferred shape of the bass reflex port 30 (30A, 30B)
will be illustrated from various viewpoints based on the description of the first embodiment and
the second embodiment. In the following description, as exemplified in the first embodiment, the
configuration A in which the inner circumferential region Q is non-circular with rotational
symmetry (configuration in which the inner diameter Φ is changed in the circumferential
direction) is conveniently referred to as “feature A Configuration in which the angle θ of the
inner diameter line L is changed according to the position of the cross section C on the central
axis X as illustrated in the second embodiment (the valley portion and the peak portion of the
inner circumferential surface 42 The spiral configuration is referred to as “feature B” for
16-04-2019
15
convenience.
[0036]
<Aspect 1> In the first embodiment, the feature A and the feature B are adopted for both the side
end 342 and the side end 344 of the bass reflex port 30, but the feature is only one of the side
end 342 and the side end 344 It is also possible to adopt A and feature B.
[0037]
FIG. 14 shows the results of measuring the level of abnormal noise for a plurality of samples in
which the presence or absence of the feature A and the feature B in each of the side end 342 and
the side end 344 is different.
The configuration M1 in FIG. 14 is a configuration (second embodiment) in which the feature A
and the feature B are adopted for both the side end 342 and the side end 344. On the other
hand, the configuration M2 is a configuration in which the feature A and the feature B are
adopted only in the side end portion 344 on the back side, and the configuration M3 is a
configuration in which the feature A and the feature B are adopted only in the side end portion
342 in the front side is there. The side end portion 342 of the configuration M2 and the side end
portion 344 of the configuration M3 adopt a flare shape in which the inner peripheral region is a
perfect circle, as in the existing port I and the existing port II.
[0038]
As can be understood from FIG. 14, the configuration M1 adopting the feature A and the feature
B at both the side end 342 and the side end 344 is the feature A and the feature B only at one of
the side end 342 and the side end 344 The noise suppression effect is large compared to (M2,
M3) when adopting. Therefore, as exemplified in the first embodiment and the second
embodiment, the configuration in which the feature A and the feature B are adopted for both the
side end 342 and the side end 344 is from the viewpoint of maximizing the effect of noise
reduction. Is preferred.
[0039]
16-04-2019
16
On the other hand, it is a reality that the cost for manufacturing the side end 34 employing the
feature A and the feature B exceeds the cost for manufacturing the simple shaped side end 34
not adopting the feature A or the feature B. Is assumed. Therefore, from the viewpoint of
reducing the manufacturing cost, a configuration in which the feature A and the feature B are
adopted for only one of the side end 342 and the side end 344 is advantageous. Referring to FIG.
14, the configuration M 2 adopting feature A and feature B at the rear side end 344 is abnormal
noise compared to the configuration M 3 adopting feature A and feature B at the front side end
342. A tendency is observed that the suppression effect of Therefore, from the viewpoint of
achieving both suppression of abnormal noise and reduction of manufacturing cost, the feature A
and the feature A at the side edge 344 on the back side are more than the configuration M3 in
which the feature A and the feature B are adopted for the side edge 342 on the front side. The
configuration M2 adopting the feature B is preferable. On the other hand, the side end 344
located inside the housing 10 is difficult to visually recognize from the outside. Therefore, from
the viewpoint of giving priority to the aesthetic appearance of the feature A and the feature B,
the configuration M3 in which the feature A and the feature B are adopted for the side end 342
that is easily visible from the outside is preferable.
[0040]
<Viewpoint 2> In each of the above-described embodiments, the configuration in which the inner
circumferential region Q is noncircular with five symmetry is illustrated, but as illustrated in FIG.
15, the rotational symmetry order N is changed to a value other than 5 It is also possible. In FIG.
15, an inner circumferential area Q from three-fold symmetry (N = 3) to seven-fold symmetry (N
= 7) is illustrated.
[0041]
FIG. 16 shows the result of measuring the level of abnormal noise for a plurality of
configurations in which the order N of rotational symmetry is changed. The symbol NA (N = 3 to
7) in FIG. 16 means a configuration in which the inner circumferential region Q is non-circular
with rotational symmetry and the feature B is not adopted, and the symbol NB indicates that the
inner circumferential region Q is rotated. It means a configuration in which the feature B is
adopted after being symmetrical and non-circular. Further, in FIG. 16, the average value of the
level of the abnormal noise of the configuration adopting feature B and the configuration not
using it is indicated by a black circle for each order N.
16-04-2019
17
[0042]
A general tendency can be confirmed from FIG. 16 that the smaller the order N of rotational
symmetry is, the larger the suppression effect of abnormal noise. Therefore, a configuration in
which the rotational symmetry order N is set to a small numerical value (for example, N = 3 to 5)
is preferable. Further, as can be understood from FIG. 16, when the rotational symmetry order N
is an odd number, it can be confirmed that the suppression effect of abnormal noise is large as
compared with the case where the order N is an even number. Therefore, a configuration in
which the rotationally symmetrical order N is set to an odd number is preferable. In the case
where the degree N is an odd number (when the geometrical symmetry of the inner
circumferential region Q is low), the noise suppressing effect is larger than that in the even
number. The above-mentioned tendency that the noise is reduced as the geometric symmetry of
the generated vortex ring is reduced is also in agreement.
[0043]
When the above tendency is comprehensively taken into consideration, the configuration in
which the rotational symmetry order N is a small odd number (for example, N = 3, 5) is
particularly preferable from the viewpoint of noise reduction. However, in the present invention,
the order N of rotational symmetry of the inner circumferential region Q is arbitrary.
[0044]
<Viewpoint 3> In the above-described embodiments, the case where the contour line of the inner
circumferential area Q is a curve over the entire circumference is exemplified, but a configuration
in which the contour line of the inner circumferential area Q includes a straight line may be
employed. For example, as illustrated in part (A) of FIG. 17, the inner circumferential region Q of
a shape (hereinafter referred to as “shape II”) in which corner portions of a rotationally
symmetric polygon (a pentagon in FIG. 17) It can be adopted. The shape II can also be expressed
as a shape in which the minimum point PB of the inner diameter Φ (the peak of the inner
circumferential surface 42) does not exist.
[0045]
16-04-2019
18
18 shows a configuration in which the inner circumferential region Q is a rotationally symmetric
closed curve (hereinafter referred to as “shape I”) as in the first embodiment (FIG. 3 or 11),
and the inner circumferential region Q is a portion of FIG. It is a graph of the result of having
measured the level of abnormal noise about each with the composition made into shape II of (A).
In FIG. 18, adoption of feature B is omitted for convenience. Referring to FIG. 18, in the
configuration in which the inner circumferential region Q is in the shape II, the tendency that the
level of the abnormal noise is higher as compared with the configuration in which the shape I is
employed is grasped. Therefore, from the viewpoint of noise reduction, the configuration in
which the inner circumferential region Q is a closed curve like the shape I illustrated in the first
embodiment is advantageous as compared to the shape II including a straight line.
[0046]
By the way, as described above in connection with the part (A) and the part (B) of FIG. 6, the level
of the abnormal sound of the existing port II having a small ellipticity of the ellipse defining the
inner peripheral surface is the existing port having a large ellipticity. I above the level of
abnormal noise. That is, as the ellipticity of the ellipse defining the inner circumferential surface
42 is larger, the noise tends to be reduced. In the shape II illustrated in FIG. 17, the range where
the ellipticity is large in the inner circumferential surface 42 (the range in which the shape is
close to the locus RA of the maximum point PA as in the broken line in FIG. 17) is compared with
the first embodiment. narrow. Therefore, it is inferred that the level of the abnormal noise is high
in the configuration in which the inner circumferential area Q is the shape II, because the range
where the ellipticity is large in the inner circumferential surface 42 is narrow.
[0047]
In consideration of the above consideration, the shape III of the portion (B) of FIG. 17 which can
sufficiently secure the range where the ellipticity of the inner peripheral surface 42 is large is
suitable as the shape of the inner peripheral region Q. FIG. 18 also shows the level of abnormal
noise perceived in the configuration adopting the shape III. As understood from FIG. 18,
according to the shape III, it is possible to enhance the suppression effect of the abnormal noise
even if the shape II as well as the shape I is of course. The above results are consistent with the
above-mentioned tendency that abnormal noise is reduced as the ellipticity of the ellipse defining
the inner circumferential surface 42 is larger. In the above description, the configuration in
which the feature B is omitted is assumed for convenience, but it is natural that the feature B can
also be adopted regardless of the shape of the inner circumferential region Q.
16-04-2019
19
[0048]
<Modifications> The above-described embodiments can be variously modified. The aspect of a
specific deformation | transformation is illustrated below. Two or more aspects arbitrarily
selected from the following examples may be appropriately combined.
[0049]
(1) In the embodiments described above, the feature A and the feature B are adopted over the
entire section (the entire area between both ends) of the side end 34, but only a specific section
(for example, the section on the tip side) of the side end 34 It is also possible to adopt feature A
and feature B. Moreover, although the intermediate part 32 was interposed between the side end
part 342 and the side end part 344 in each above-mentioned form, the intermediate part 32 may
be abbreviate | omitted. Therefore, it is also possible to adopt the feature A and the feature B
over the entire section of the bass reflex port 30.
[0050]
(2) In the second embodiment, the bass reflex port 30B having both the feature A and the feature
B is illustrated, but the feature A is not an essential requirement for the feature B, and the feature
A is omitted from the second embodiment. Is also possible. That is, in the feature B (second
embodiment) in which the ridges or valleys of the inner circumferential surface 42 are formed in
a spiral shape, the specific shape of the inner circumferential region Q is arbitrary. However,
when the inner circumferential area Q is a perfect circle, the rotation of the inner diameter line L
according to the position of the cross section C can not be conceived, so the shape of the inner
circumferential area Q in the feature B is naturally non-circular.
[0051]
(3) In the embodiments described above, the configuration in which the inner diameter line L
rotates in one direction with respect to the movement of the cross section C on the central axis X
(the angle θ of the inner diameter line L with respect to the movement of the cross section C is
16-04-2019
20
monotonous Although the configuration of increasing or monotonically decreasing is illustrated,
the rotation direction of the inner diameter line L with respect to the movement of the cross
section C is not limited to the above illustration. For example, a configuration may be employed
in which the rotation direction of the inner diameter line L is reversed at a position midway of
the side end 34. Moreover, the continuity of the change of the angle θ of the inner diameter line
L is not an essential requirement. That is, a configuration in which the angle θ changes
discontinuously with respect to the movement of the cross section C can also be adopted. As
understood from the above description, in the preferred embodiment of the present invention,
the angle θ of the inner diameter line L in the cross section (first cross section) CA on the central
axis X and the cross section CA on the central axis X The angle θ of the inner diameter line L in
the cross section (second cross section) CB having a different position is comprehensively
expressed as a configuration having a difference.
[0052]
(4) In the above-described embodiments, the bass reflex port 30 employed in the speaker device
100 is illustrated. However, the features of the bass reflex port 30 in each of the above
embodiments may be applied to a tube other than the bass reflex port 30. As a pipe body to
which the present invention can be applied, for example, a muffler of a vehicle such as a twowheeled vehicle or a four-wheeled vehicle, an intake / exhaust duct of an air conditioner, etc. can
be exemplified. The present invention can also be applied to a tube body of an instrument
(typically a wind instrument) such as a brass instrument or a woodwind instrument.
[0053]
100: speaker device, 10: housing, 12: plate material on the front side, 14, 16: opening, 20:
speaker unit, 30A, 30B: bass reflex port, 32: middle part, 34 ( 342, 344) ...... Side end, 42 ......
Inner circumferential surface, Q ...... Inner circumferential region.
16-04-2019
21
Документ
Категория
Без категории
Просмотров
0
Размер файла
39 Кб
Теги
description, jp2016027730
1/--страниц
Пожаловаться на содержимое документа