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DESCRIPTION JPH11252686

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DESCRIPTION JPH11252686
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker, and more particularly to a speaker provided with a speaker frame made of FRP.
[0002]
2. Description of the Related Art There is a strong demand for further weight reduction in recent
speakers, particularly in-vehicle speakers. The weight reduction of the magnetic circuit part and
the frame is the main focus in the weight reduction of the speaker, but in the weight reduction of
the frame, FRP is excellent in mechanical strength and extremely favorable for weight reduction,
particularly as a reinforcing fiber FRP using a certain carbon fiber (hereinafter referred to as
"CFRP". The speaker frame molded in) is very advantageous.
[0003]
As described above, CFRP is an extremely advantageous material as a frame material both in
terms of strength and weight reduction, but since a CFRP frame does not undergo plastic
deformation, it can be used for ordinary internal magnetic type magnetic circuits as shown in
FIG. In the speaker, when the magnetic circuit portion M is crimped to the bottom portion 12 of
the frame 1 in the normal mode, when a predetermined pressure is applied to the crimped
portion, as shown in FIG. There is a defect that a crack C occurs in the part and the reliability in
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mounting of the magnetic circuit part M can not be secured. In the figure, Vc is a voice coil, Df is
a diaphragm, E is an edge, and S is a damper.
[0004]
A mode for caulking the magnetic circuit unit M will be described. As shown in FIG. 8, a plate M3
as a magnetic circuit component is provided with a dowel M3D having a predetermined diameter
and height, and the frame bottom 12 is compatible with the dowel M3D. The dowel M3D is
caulked to the frame 1 by means such as cutting the dowel M3D from the top or crushing the
long part as shown in FIG. The Rukoto.
[0005]
When the above-mentioned dowel M3D is crimped on a metal frame 1 such as an iron plate
frame or an aluminum frame, the caulking portion of the frame 1, that is, the hole 12h into which
the dowel M3D is inserted is plastically deformed to absorb stress due to caulking. Although
possible, since CFRP does not plastically deform, a crack C as shown in FIG. 9 is generated when
dowel squeezing pressure is applied to the crimped portion (crimping hole 12h) of the frame 1
when the magnetic circuit is attached.
In addition, since the internal loss of the frame is small in the CFRP frame, there is a defect that
when the input signal is added to the speaker on which the CFRP frame is mounted, resonance
occurs easily at a specific frequency.
[0006]
The cause of this resonance is caused by the repulsion operation of the magnetic circuit M
attached to the frame 1 and depends on the shape of the frame 1 and the weight balance of the
attached magnetic circuit M. For example, if the shape of the frame 1 is constant and the weight
of the magnetic circuit M increases, the resonance frequency band decreases and the resonance
power also increases. If this frequency band is within the audible range, the sound quality is
extremely adversely affected.
[0007]
Therefore, we use a neodymium magnet that is extremely lightweight to reduce the weight of the
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magnetic circuit part, and place the two magnets facing each other with the center plate made of
magnetic material facing the same center. A speaker structure was proposed separately in which
a repulsive magnetic circuit structure was formed so as to form a magnetic field due to repulsive
magnetism generated on the outer periphery of the plate, and for weight reduction of the frame,
a CFRP frame as described above was adopted.
[0008]
In this speaker structure, a repulsive magnetic circuit structure using a neodymium magnet is
used as a defect that easily resonates, the repulsion operation by the magnetic circuit section is
greatly reduced to suppress the resonance, and the repulsive magnetic magnet frame is made as
a CFRP frame. In order to prevent the occurrence of cracks due to caulking, the magnetic circuit
portion is mounted by a method other than caulking in order to prevent the occurrence of cracks
due to caulking. .
That is, as a point of adopting a CFRP frame, it is premised to adopt a repulsion type magnetic
circuit structure using a neodymium magnet in order to reduce the weight of the magnetic circuit
part.
[0009]
On the other hand, we can use the CFRP frame as a speaker frame equipped with a conventional
magnetic circuit that is generally used in the past, taking advantage of the lightness and
toughness of the CFRP frame. As a result of various researches on the properties, it has been
found that it is difficult to completely eliminate the occurrence of cracks due to caulking
attachment of the magnetic circuit part in a frame made of CFRP molded in a normal form.
[0010]
Taking a 6.5-inch aperture speaker most frequently used as a car-mounted speaker as an
example, a typical magnetic circuit section M (hereinafter referred to as "ferrite magnet") using a
ferrite magnet M1 at present based on FIG. 7 and FIG. It is referred to as a circuit unit M ".
The magnet M1 has a ring shape having an outer diameter of 75 mm, an inner diameter of 32
mm, and a thickness of 10 mm, and has a weight of 184 g. The diameter of the bottom portion of
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the yoke M2 is 70 mm, the diameter of the pole is 25.4 mm, and the weight is 191 g. The plate
M3 has an outer diameter of 70 mm, an inner diameter of 27.75 mm, a thickness of 4 mm, and a
weight of 108 g. The total weight of the ferrite magnetic circuit portion M is 483 g.
[0011]
Also, instead of a ferrite magnet, a magnetic circuit unit M using a neodymium magnet with
much higher magnetic performance (hereinafter referred to as "neodymium magnetic circuit unit
M". In the case of the above, the weight can be reduced by about 54% compared to the ferrite
magnetic circuit part M, and the total weight of the magnetic circuit part is about 260 g.
Incidentally, the total weight of the neodymium repelling magnetic circuit portion of the speaker
structure separately proposed by us is 65 g. The weight of the metal frame 1 generally used
conventionally is about 140 g for a press frame of an iron plate (0.7 t) and about 60 g for a press
frame of an aluminum plate (1 t), and the resin by injection molding In the case of a frame, it is
about 80 g.
[0012]
Also, in the case of an aluminum frame, even with an aluminum frame (about 40 g) having a
plate thickness of 0.7 mm, deterioration in sound quality due to resonance of frame 1 does not
significantly appear within the generally used range, and the required strength as frame 1 Is
secured. However, since such an aluminum frame with a thickness of 0.7 mm is about half as
strong as an iron plate frame with the same thickness of 0.7 mm, when mounting the speaker of
this aluminum frame in a vehicle interior There is a risk that the mounting flange portion of the
speaker may be deformed in screwing work or the like.
[0013]
In order to cope with such a danger, the screwing deformation of the flange portion is prevented
at present by increasing the thickness of the frame 1 from 0.7 mm to 1 mm. That is, the strength
of the flange portion is enhanced by increasing the overall strength of the frame 1, and naturally,
the weight of the frame 1 is also increased from about 40 g to about 60 g.
[0014]
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From the above, it is lighter than the conventional aluminum frame, and even if the ferrite
magnetic circuit portion M of about 480 g to 500 g is attached to the frame 1, it withstands the
practical impact including the drop test, and the specific frequency Require a frame made of
CFRP that is difficult to resonate.
[0015]
SUMMARY OF THE INVENTION To reduce the weight of the frame as a CFRP frame, an increase
in the weight of a screw is required when screwing, not caulking, when mounting the magnetic
circuit portion on the frame. However, it is more advantageous to reduce the weight of the frame.
In addition, since the mounting of the magnetic circuit portion M may be premised on screwing
as described above, there is no concern about the occurrence of a crack or the like in the
mounting portion of the magnetic circuit portion M as in the prior art.
[0016]
On the other hand, with regard to resonance, as is well known, it is possible to prevent the
occurrence of resonance by increasing the strength of the frame itself, but in the case of a CFRP
frame, it is possible to increase the thickness of the molded frame It is easy to improve the
strength by increasing the thickness of the frame after molding by increasing the number of
laminated base cloths made of woven or non-woven cloth made of carbon fiber. However, carbon
fibers used as reinforcing fibers of FRP are lightweight and high in strength but expensive.
[0017]
Therefore, simply increasing the number of woven or non-woven cloths made of carbon fibers is
not practical because the cost increases, and it is characteristic of CFRP that all the reinforcing
fibers are carbon fibers with little internal loss. It is difficult to fundamentally change the nature
of resonance.
[0018]
As a result of various studies to solve the problems as described above, by improving the
laminated structure of the CFRP frame, it is possible to reduce the weight of the frame and to
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reduce the weight of the entire speaker, and also extremely heavy. It has been found that the
occurrence of resonance or the like can be suppressed even if the conventional internal magnet
type magnetic circuit unit by a conventional ferrite magnet is mounted.
[0019]
Therefore, an object of the present invention is to provide a speaker capable of reducing the
weight of the frame and reducing the weight of the entire speaker without increasing the cost
and suppressing the occurrence of resonance and the like.
[0020]
In the speaker according to the present invention, a base fabric made of woven or non-woven
fabric is coated with a synthetic resin to make it into a prepreg state, and a plurality of base
fabrics in the prepreg state are used. The speaker frame is formed into a predetermined shape by
heat pressure molding or the like, and the frame is characterized in that a layer of pulp is
interposed between the base fabrics.
[0021]
A second aspect of the present invention is characterized in that the fibers constituting the
woven or non-woven fabric are carbon fibers.
[0022]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiment of the
speaker according to the present invention will be described with reference to FIGS. 1 to 6. The
same reference numerals are given to the same components as the conventional components
described based on FIGS. The explanation is omitted.
[0023]
In the figure, 1 is a frame of the speaker, and M is a magnetic circuit unit.
The frame 1 is coated with a synthetic resin on a woven or non-woven base fabric to make it into
a prepreg state, and a plurality of sheets of the base fabric in the prepreg state are stacked and
molded into a predetermined shape by heat pressure molding etc. The layer of pulp intervenes in
the
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[0024]
The raw material of CFRP used in this example is a woven fabric in which carbon fibers in a flat
state with 3000 filaments are flat-woven with 13 warps and wefts per 1 inch and the number of
strikes per 1 inch (hereinafter referred to as "carbon woven fabric" .
And the carbon woven fabric is further coated with a vinyl ester resin in a weight corresponding
to about 40% of the weight per 1 m 2 of the woven fabric, and the resin is in the form of a
prepreg generally referred to as B-stage. Carbon woven fabric (hereinafter referred to as "B
carbon woven fabric CF".
Got).
[0025]
A normal CFRP laminates an arbitrary number of the B carbon woven fabric CF and is formed
into an arbitrary shape by hot pressure molding. In the present embodiment, a pulp layer 1P is
provided between the CFRP laminations.
A pulp cup (hereinafter referred to as "pulp cup PC") adapted to the shape of the frame 1 in order
to form the pulp layer 1P.
Got).
The pulp cup PC is obtained by beating an arbitrary pulp material and making it into a shape of a
frame 1 with a papermaking die produced, and hot-air drying the obtained frame-shaped
papermaking.
[0026]
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The weight of the pulp cup PC is about 6 g, and the average meat pressure is about 0.8 mm. The
pulp cup PC is placed in the lower molding die D2 as shown in FIG. 2, the B carbon cloth CF is
placed on the next pulp cup PC, and the upper die D1 is lowered as shown in FIG. Hot press
molding (hereinafter referred to as "primary molding"). Hot press molding conditions are the
same as general CFRP hot press molded products, upper and lower molds D1, D2 temperature is
140 ° C, press pressure is 15 tons (axial output), press time is 3 minutes It is.
[0027]
In primary molding, as shown in the enlarged view of FIG. 3, fibers of carbon woven fabric CF
stick to the surface of the pulp cup PC, and a vinyl ester resin is cured to form a CFRP molded
article with so-called pulp cup PC. can get. As shown in FIG. 4, this primary molded product (PC +
CF) is adsorbed to the upper mold D1 of the secondary molding mold and installed, and the B
carbon woven fabric CF is disposed on the next lower mold D2. When hot pressing is performed
in the same manner as in the primary molding, as shown in FIG. 5, a cup-shaped molded article is
completed in a state where the pulp layer 1P is sandwiched by the CFRP molded layer.
[0028]
The cross section of this frame-shaped secondary molded product will be described with
reference to FIG. 1. The maximum external dimension is 162.3 mm in the outer diameter of the
mounting flange 11 portion. The flange 11 is a mounting portion of the edge E of the diaphragm
Df, and has an inner diameter of 128 mm, and an outer peripheral portion of the flange is
provided with a rising portion of about 6.2 mm. The maximum depth dimension from the rising
portion is 39.4 mm, and the damper seat 13 having an outer diameter of 80 mm and a width of
5.3 is provided at a depth of 22.2 mm from the rear surface of the flange. The lower part is a
bottom 12, and the bottom 12 is a mounting part of the magnetic circuit unit M.
[0029]
After the secondary molded product is taken out of the molding dies D1 and D2, as shown in FIG.
6, an unformed and surplus portion on the outer peripheral portion of the flange 11 of the
molded product is cut away by a punching press or the like. Furthermore, in order to form a
frame post portion between the flange portion 11 and the damper seat 13 through a hole for
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attaching the frame to the flange 11 portion, a trimming process is performed in which an extra
portion other than the post is punched out and cut out. Completed as frame 1 for the speaker.
The finished weight of the CFRP frame 1 was about 38 g.
[0030]
As shown in FIG. 1, using the frame 1, an internal magnetic type magnetic circuit M by ferrite
magnet having a weight of about 485 g is attached to the magnetic circuit mounting portion
provided on the frame bottom 12 with four 4 mm screws b (90 degrees A speaker was
manufactured in the same manner as in the prior art, with the other assembly configurations
fixed. The completed weight of this speaker was about 530 g, and when the frequency
characteristics were further measured, it showed characteristics equivalent to those of the
conventional speaker and was not different from the performance of the speaker provided with
the conventional ferrite magnetic circuit unit M.
[0031]
In addition, it withstands impact tests such as drop tests, and the strength of flanges 11 for
mounting is also sufficient. Almost no deformation due to screw tightening is observed in various
mounting experiments, and there is no problem in the practical range at all. Was confirmed.
Furthermore, as a result of comparison audition between the speaker of the present embodiment
and the conventional metal frame, no problems due to the CFRP frame of the present
embodiment, in particular, deterioration of sound quality due to resonance, etc. were found.
[0032]
In the present embodiment, in order to give priority to weight reduction, the reinforcing fiber is
made of CFRP consisting of carbon fiber, but depending on the purpose of use, for example, a
general FRP consisting of glass fiber may be used. Of course.
[0033]
According to the speaker of the present invention, a base fabric made of woven fabric or nonwoven fabric is coated with a synthetic resin as a speaker frame to make it into a prepreg state,
and a plurality of base fabrics in the prepreg state are piled up and heat pressure molded etc.
And a frame in which a layer of pulp is interposed between the above-mentioned base fabrics, so
that molding is carried out in a state in which the pulp layer is sandwiched between the base
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fabrics such as woven fabrics to be reinforced fibers. By doing this, it is possible to easily
increase the thickness of the molded product, and as a result, the frame strength is dramatically
improved, and the pulp has a high weight ratio strength. However, it is extremely effective in
reducing the weight, and the object can be achieved at low cost and low cost.
[0034]
In addition, since pulp has more internal loss than resin or reinforcing fibers, etc., the damping
effect is easily exhibited to a great extent, which is extremely effective for suppressing the
occurrence of resonance of the frame made of FRP molded article, and in particular, the internal
loss is small. Basically, since the pulp layer is provided as a frame made of CFRP which easily
generates resonance, the generation of resonance can be extremely effectively suppressed.
[0035]
Furthermore, by providing a pulp layer, the pulp layer exhibits appropriate cushioning
properties, and when attaching a magnetic circuit part to a CFRP frame when attaching it by
caulking, the caulking part of the frame is appropriately deformed to attach the frame. Cracks do
not occur around the hole.
Therefore, in mounting the magnetic circuit unit on the frame, caulking mounting can be
performed at a lower cost than mounting by screwing, which is effective in cost reduction.
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