U.S. patent application number 10/574858 was filed with the patent office on 2007-03-15 for hermetic compressor and manufacturing method of suction muffler.
This patent application is currently assigned to MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.. Invention is credited to Ko Inagaki, Akira Nakano.
Application Number | 20070059189 10/574858 |
Document ID | / |
Family ID | 34656101 |
Filed Date | 2007-03-15 |
United States Patent
Application |
20070059189 |
Kind Code |
A1 |
Nakano; Akira ; et
al. |
March 15, 2007 |
Hermetic compressor and manufacturing method of suction muffler
Abstract
This relates to a hermetic compressor and a manufacturing method
of a suction muffler, and discloses a technique for making energy
efficiency higher and reducing noise. According to that technique,
in a suction muffler 140 having a sound attenuation space 143, by
foam-molding a wall 147, such as an opposite surface and the like,
where open ends 145a, 146a within the sound attenuation space among
the walls constituting a casing 140C of the suction muffler 140 are
opened, it is possible to reduce the heating action of refrigerant
gas released into the sound attenuation space 143 effectively in a
space-saving manner, and make a sucking efficiency higher, and
effectively absorb a refrigerant pulsation tone radiated in the
open end 145a within the sound attenuation space, and consequently
reduce the noise.
Inventors: |
Nakano; Akira; (Kyoto,
JP) ; Inagaki; Ko; (Kanagawa, JP) |
Correspondence
Address: |
STEVENS, DAVIS, MILLER & MOSHER, LLP
1615 L. STREET N.W.
SUITE 850
WASHINGTON
DC
20036
US
|
Assignee: |
MATSUSHITA ELECTRIC INDUSTRIAL CO.,
LTD.
1006, Osaka Kadoma, Kadoma-shi
Osaka
JP
571-8501
|
Family ID: |
34656101 |
Appl. No.: |
10/574858 |
Filed: |
October 8, 2004 |
PCT Filed: |
October 8, 2004 |
PCT NO: |
PCT/JP04/15300 |
371 Date: |
April 6, 2006 |
Current U.S.
Class: |
417/415 |
Current CPC
Class: |
F04B 39/0072
20130101 |
Class at
Publication: |
417/415 |
International
Class: |
F04B 35/04 20060101
F04B035/04 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 10, 2003 |
JP |
2003-3520321 |
Apr 21, 2004 |
JP |
2004-1252321 |
Claims
1. A hermetic compressor including: a motor element within a
hermetic vessel; a compression element driven by said motor
element; and a suction muffler made of synthetic resin which is
linked to said compression element, wherein at least a part of a
casing of said suction muffler is foam-molded.
2. The hermetic compressor according to claim 1, wherein a bubble
diameter obtained by said foam-molding is 50 .mu.m or less.
3. The hermetic compressor according to claim 1, wherein a material
of said foam-molding is crystal synthetic resin.
4. The hermetic compressor according to claim 1, wherein a skin
layer in which a bubble does not exist substantially is formed on a
surface of said foam-molding.
5. The hermetic compressor according to claim 4, wherein a
thickness of said skin layer is 30% or less of a plate thickness in
the thinnest portion.
6. The hermetic compressor according to claim 1, wherein a foaming
magnification of said foam-molding is 1.2 times or more.
7. The hermetic compressor according to claim 1, wherein among a
plurality of walls constituting said casing, a plate thickness of
the wall in which the maximum projection area is obtained is
thicker than plate thicknesses of the other plate thicknesses.
8. The hermetic compressor according to claim 1, wherein said
casing is produced by combining at least two parts, and said two
parts are separated and divided in a direction substantially
vertical to the wall in which the maximum projection area of said
casing is obtained.
9. The hermetic compressor according to claim 1, wherein plate
thicknesses of a corner of said casing and a portion having a high
curvature are relatively larger than the other portions.
10. The hermetic compressor according to claim 1, wherein said
suction muffler includes a sound attenuation space formed inside
said casing, a first linkage path to link said compression element
and said sound attenuation space, and a second linkage path to link
an inner portion of said hermetic vessel and said sound attenuation
space, and wherein a wall of said casing, which is close to at
least one of said motor-element, said compression element, an open
end within said sound attenuation space of said first linkage path,
and an open end within said sound attenuation space of said second
linkage path is designed so as to have at least one of a
configuration that it is thicker than the other walls of said
casing and a configuration that it is higher in foaming
magnification.
11. The hermetic compressor according to claim 1, wherein a
lubricating oil is stored in said hermetic vessel, and at least one
of walls of said casing of said suction muffler to which said
lubricating oil is supplied is designed so as to have at least one
of a configuration that it is thicker than the other walls of said
casing and a configuration that it is higher in foaming
magnification.
12. The hermetic compressor according to claim 1, wherein the
casing of said suction muffler has a suction muffler body and a
suction muffler cover, and wherein a bonding portion between said
suction muffler body and said suction muffler cover has a foaming
magnification which is relatively lower as compared with portions
except said bonding portion, or it is not foam-molded.
13. The hermetic compressor according to claim 1, wherein the
linkage path to link the inner portion of said hermetic vessel and
the sound attenuation space of said suction muffler is formed
integrally with the farthest element from the motor element, among
a plurality of elements constituting the casing of said suction
muffler.
14. The hermetic compressor according to claim 1, wherein a part of
the casing of said suction muffler is interposed between a cylinder
head and a valve plate which constitute said compression element,
and said interposed part of said casing has a relatively low
foaming magnification or it is not foam-molded.
15. The hermetic compressor according to claim 1, wherein a part of
the casing of said suction muffler is interposed between a cylinder
head and a valve plate which constitute said compression element,
and the thickness of said interposed part of said casing is thicker
than the other portions.
16. The hermetic compressor according to claim 1, wherein said
motor element is inverter-driven at a rotation number including a
rotation number less than a commercial power supply frequency.
17. The hermetic compressor according to claim 16, wherein said
rotation number is 20 r/sec or less.
18. The hermetic compressor according to claim 1, wherein a
refrigerant gas compressed by said compression element is
R600a.
19. A manufacturing method of a suction muffler, which foam-molds
at least a part of a casing of a suction muffler made of synthetic
resin for a hermetic compressor, wherein in said molding course, a
core-back is used to move a part of a die, enlarge a cavity and
make a plate thickness thicker.
20. A manufacturing method of a suction muffler, which foam-molds
at least a part of a casing of a suction muffler made of synthetic
resin for a hermetic compressor, wherein a section area of a gate
serving as a resin supplying portion to cavities inside a die is
equal to or greater than 70% of a square of a plate thickness of
said casing.
21. A manufacturing method of a suction muffler, which foam-molds
at least a part of a casing of a suction muffler made of synthetic
resin for a hermetic compressor, wherein two or more gates serving
as resin supplying portions to cavities inside a die are installed
for at least one unit.
Description
TECHNICAL FIELD
[0001] The present invention relates to a hermetic compressor for
use in a refrigerator, an air conditioner, a freezing refrigerating
apparatus or the like, and more particularly relates to its suction
muffler and an improvement of its manufacturing method.
BACKGROUND ART
[0002] In recent years, a hermetic compressor used in a freezing
refrigerating apparatus or the like strongly desires that energy
efficiency is high, in addition to a fact that the noise caused by
an operation is low.
[0003] As a conventional hermetic compressor, there is a hermetic
compressor whose energy efficiency is improved by improving the
sound attenuation effect of a suction muffler and effectively using
the sound attenuation effect and consequently increasing the
refrigerant circulation quantity into a compression chamber (for
example, refer to the following patent document 1).
[0004] Also, there is a hermetic compressor whose energy efficiency
is improved by maintaining the refrigerant gas, which is returned
from a freezing cycle, at the state of a low temperature and high
density and sucking into the compression room (for example, refer
to the following patent document 2). [0005] Patent Document 1:
Laid-open Unexamined Patent Publication No. 2003-42064 [0006]
Patent Document 2: Laid-open Unexamined Patent Publication No.
11-303739
[0007] The configuration of the above-mentioned conventional
hermetic compressor will be described below with reference to the
drawings.
[0008] FIG. 17 is a sectional view of the conventional hermetic
compressor, FIG. 18 is a sectional view of a suction muffler in
FIG. 19, and FIG. 19 is a flow velocity vector diagram showing the
behavior of the refrigerant gas by using the flow vector within the
suction muffler shown in FIG. 18.
[0009] In FIG. 17, a hermetic vessel 1 accommodates: a motor
element 5 composed of a rotator 4 and a stator 3 holding a coil
portion 2; and a compression element 6 driven by the motor element
5. A lubricating oil 8 is stored in the hermetic vessel 1.
[0010] The schematic configuration of the compression element 6
will be described below. A crank shaft 10 has: a main shaft portion
11 where the rotator 4 is press-fitted and fixed; and an eccentric
portion 12 formed eccentrically to the main shaft portion 11.
Inside the main shaft portion 11, an oil pump 13 is placed so as to
be opened in the lubricating oil 8.
[0011] A cylinder block 20 formed above the motor element 5 has: a
compression room 22 that is approximately cylindrical; and a shaft
supporter 23 that supports the main shaft portion 11 with a shaft.
A piston 30 is inserted into the compression chamber 22 of the
cylinder block 20 so as to be reciprocatingly slidable therein, and
linked to the eccentric portion 12 by a linking device 31.
[0012] A valve plate 35 for sealing the open end surface of the
compression room 22 has a suck hole 38 to be linked to the
compression room 22 in accordance with the opening/closing action
of a suction valve 34. A cylinder head 36 is fixed through the
valve plate 35 to the opposite side to the compression room 22.
[0013] A suction tube 37 is fixed to the hermetic vessel 1 and
connected to the low pressure side (not shown) of a freezing cycle,
and introduces the refrigerant gas (not shown) into the hermetic
vessel 1. A suction muffler 40 is fixed because it is interposed
between the valve plate 35 and the cylinder head 36, and it is made
of synthetic resin, such as polybutylene telephthalate and the
like, to which glass fiber is mainly added.
[0014] In FIG. 18, the suction muffler 40 has a sound attenuation
space 43 and also has: a second linkage path 46 where an open end
46b is linked into the hermetic vessel 1 and an open end 46a is
opened while extended to the sound attenuation space 43; and a
first linkage path 45 where an open end 45b is linked to the suck
hole 38 of the valve plate 35 and an open end 45a is opened while
extended to the sound attenuation space 43.
[0015] FIG. 19 shows flow velocity vectors 60 indicating the
behavior of the refrigerant gas within the suction muffler 40
obtained by a computer simulation. The length of each vector
indicates the magnitude of the flow velocity, and the orientation
of the vector indicates the flow direction of the refrigerant
gas.
[0016] Also, respective arrows indicate an upper eddy 61 generated
by the upstream flows in the refrigerant gas sucked from the open
end 46a of the second linkage path 46, and a lower eddy 62
generated by the downstream flow in the refrigerant gas sucked from
the open end 46a of the second linkage path 46.
[0017] The operation of the conventional hermetic compressor
configured as mentioned above will be described below.
[0018] When the rotator 4 of the motor element 5 rotates the crank
shaft 10, since the rotation motion of the eccentric portion 12 is
transmitted through the linking device 31 to the piston 30, the
piston 30 reciprocates inside the compression room 22. Due to this
operation, the refrigerant gas is introduced into the hermetic
vessel 1 through the suction tube 37 from the cooling system (not
shown). The refrigerant gas introduced into the hermetic vessel 1
is sucked from the open end 46b of the suction muffler 40, and
released to the sound attenuation space 43 from the open end
46a.
[0019] The released refrigerant gas, after colliding with the wall
of the casing of the suction muffler 40 that is close and opposite
to the open end 46a as shown in FIG. 19, generates the upper eddy
61 and the lower eddy 62, and circulates through the sound
attenuation space 43. After that, the refrigerant gas mainly
constituted by the upper eddy 61 is sucked from the open end 45a to
the first linkage path 45 and introduced into the suck hole 38
opened in the valve plate 35.
[0020] Then, when the suction valve 34 is opened, the refrigerant
gas is sucked into the compression room 22, and compressed by the
reciprocating motion of the piston 30, and discharged into the
cooling system.
[0021] Here, the pressure pulsation of the refrigerant induced when
the refrigerant is sucked into the compression room 22 is
propagated in the direction opposite to the flow of the refrigerant
as mentioned above and propagated from the open end 45a to the
sound attenuation space 43. Here, since the first linkage path 45
is extended into the sound attenuation space 43 where the sound
attenuation effect is high, and the open end 45a is located in the
node of the sound, for example, in the 3 to 4 kHz region where the
noise becomes troublesome, it is possible to obtain the high sound
attenuation effect in a particular frequency band.
[0022] Also, the noise pulsation attenuated in the sound
attenuation space 43 is further attenuated by adjusting the
dimension of the sound attenuation space 43 and the length and
inner diameter of the second linkage path 46. Thus, it is possible
to obtain the higher sound attenuation effect.
[0023] Also, FIG. 20 shows a sectional view of a suction muffler of
another conventional hermetic compressor. Another conventional
example will be described below with reference to the drawings. By
the way, the entire configuration except the suction muffler is
similar to the above-mentioned conventional example. Thus, the
detailed explanation is omitted.
[0024] In FIG. 20, a suction muffler 50 has a resonant space 58
placed so as to surround a suction space 57. In a second linkage
path 56, one end is linked to the hermetic vessel 1, and the other
end is linked o the suction space 57. In a first linkage path 55,
an open end 55a is opened to the suction space 57, and the other
end is linked through the suction valve 34 to the compression room
22, and this has a linkage hole 59 to link the first linkage path
55 and the resonant space 58.
[0025] The operation of another conventional hermetic compressor
configured as mentioned above is explained.
[0026] The refrigerant gas of a low temperature returned from a
freezing system (not shown), after sucked into the suction space 57
of the suction muffler 50 from the second linkage path 56, is
sucked into the compression room 22 from the first linkage path 55.
At this time, since the suction space 57 is surrounded by the
resonant space 58, the suction space 57 is thermally insulated by
the refrigerant gas in the resonant space 58 and the wall portion
constituting the casing of the resonant space 58.
[0027] Consequently, the refrigerant gas inside the suction space
57 is not directly heated by the refrigerant gas of a high
temperature within the hermetic vessel 1, and the refrigerant gas
of a high density can be sucked into the compression room 22. Thus,
the suck efficiency can be made higher. Also, since the resonant
space 58 is linked through the linkage hole 59 to the suction space
57, it acts as a resonant room, and the noise can be reduced.
[0028] However, in the conventional configuration, the refrigerant
gas, which is sucked into the suction muffler 40 through the
hermetic vessel 1 from the cooling system (not shown) by the
reciprocating motion of the piston 30 and released to the sound
attenuation space 43 from the second linkage path 46, as shown in
FIG. 19, does not directly flow into the first linkage path 45, and
it collides with the wall of the casing of the suction muffler 40,
which is close and opposite to the open end 46a, and then generates
the upper eddy 61 and the lower eddy 62 and circulates through the
sound attenuation space 43.
[0029] For this reason, the heat-exchange is carried out between
the refrigerant gas of the low temperature returned from the
cooling system and the refrigerant gas of the high temperature
within the hermetic vessel 1. Thus, it is greatly heated.
[0030] Moreover, after the circulation flow generated by the upper
eddy 61 and the lower eddy 62 is heated by the refrigerant gas
whose temperature is increased due to the stay inside the sound
attenuation space 43, it is sucked from the open end 45a and flows
into the compression room 22. Thus, this has a problem that the
mass flow quantity of the refrigerant which can be sucked into the
compression room 22 is reduced and the suck efficiency is
dropped.
[0031] Also, the open end 45a is close and opposite to the wall of
the casing of the suction muffler 40. Thus, the wall of the casing
of the close opposite suction muffler 40 is vibrated by the
influence of the open end 45a in which the pressure pulsation
becomes maximum. The pulsation sound of the refrigerant is radiated
out of the casing of the suction muffler 40. Hence, this has a
problem that the noise is increased.
[0032] On the other hand, in another conventional hermetic
compressor configuration, the suction space 57 constituting the
suction muffler 50 is placed so as to be surrounded by the resonant
space 58. Thus, it is possible to protect the refrigerant gas
within the suction space 57 from being directly heated by the
refrigerant gas of the high temperature inside the hermetic vessel
1, and possible to make the suck efficiency higher. However, the
whole of the suction space 57 is configured so as to be surrounded
by the resonant space 58. Thus, this has problems that the entire
dimension of the suction muffler 50 becomes bigger and the number
of parts becomes greater or the molding becomes complex.
DISCLOSURE OF THE INVENTION
[0033] The present invention solves the above-mentioned
conventional problems and has an object to provide the hermetic
compressor in which the suck efficiency is high and the noise
vibration is small, and the manufacturing method of the suction
muffler.
[0034] In order to solve the above-mentioned conventional problems,
in the hermetic compressor of the present invention, at least -a
part of a casing of the suction muffler is foam-molded. Thus, due
to the thermal insulating effect of bubbles generated within foamed
synthetic resin, this has an action of extremely improving the
thermal insulating performance under the same volume, and dropping
the loss caused by heat reception, as compared with non-foamed
resin, and also has an action of increasing the acoustic
transmission loss because acoustic energy is absorbed by the
friction between the gas within the bubble and the synthetic resin
material around the bubble.
[0035] The hermetic compressor of the present invention can make
the suck efficiency of the refrigerant gas higher and reduce the
noise vibration.
[0036] One aspect of the present invention has a motor element
inside a hermetic vessel, a compression element driven by the motor
element, and a suction muffler made of synthetic resin that is
linked to the compression element, and at least a part of a casing
of the suction muffler is foam-molded. Thus, due to the thermal
insulating effect of the bubbles generated within the foamed resin,
the thermal insulating performance is extremely improved as
compared with the resin of the non-foamed solid material. Also, the
heat reception from the refrigerant gas of a low temperature sucked
into the suction muffler can be largely reduced, thereby making the
suck efficiency higher. Moreover, the absorption of the acoustic
energy caused by the friction between the gas within the bubble and
the material around the bubble increases the acoustic transmission
loss, which enables the reduction in the noise vibration.
[0037] In another aspect of the present invention, the bubble
diameter obtained by the foam-molding is 50 .mu.m or less. Thus, by
reducing the bubble diameter generated within the foamed resin, the
number of the bubbles is increased to make the thermal insulating
effect higher. Hence, in addition to the above-mentioned effects,
the suck efficiency can be made higher.
[0038] In another aspect of the present invention, the material of
the foam-molding is crystal synthetic resin. Thus, as the feature
of the crystal synthetic resin, the chemical resistance is high,
and the solubility of the resin material to the refrigerant and the
lubricating oil is dropped. Thus, in addition to the
above-mentioned effects, it is possible to further improve the
reliability of the compressor and carry out the stable
operation.
[0039] In another aspect of the present invention, the skin layer
where the bubble does not exist substantially is formed on the
surface of the foam-molding. Thus, the refrigerant and the
lubricating oil are hard to permeate into the suction muffler.
Hence, in addition to the above-mentioned effects, it is possible
to further improve the reliability of the compressor and carry out
the stable operation.
[0040] In another aspect of the present invention, the thickness of
the skin layer is 30% or less of the plate thickness in the
thinnest portion. Thus, by thinning the skin layer which has no
bubble and has the low thermal insulating property, it is possible
to make the foaming magnification higher, improve the thermal
insulating property and make the suck efficiency higher, in
addition to the above-mentioned effects.
[0041] In another aspect of the present invention, the foaming
magnification of the foam-molding is 1.2 times or more. Thus, since
the excellent thermal insulating performance is obtained, it is
possible to make the suck efficiency higher and obtain the
excellent absorption effect of the acoustic energy. Hence, in
addition to the above-mentioned effects, the noise vibration can be
further reduced.
[0042] In another aspect of the present invention, among a
plurality of walls constituting the casing, the plate thickness of
the wall where the maximum projection area is obtained is thicker
than the plate thicknesses of the other walls. Thus, since the
space enabling the foaming is enlarged, in addition to the
above-mentioned effects, the foaming magnification of the surface
occupying most of the surface area can be made higher, thereby
improving the thermal insulating property and making the suck
efficiency higher.
[0043] In another aspect of the present invention, the casing is
produced by combining at least two parts, and the two parts are
separated and divided in the direction substantially vertical to
the wall where the maximum projection area of the casing is
obtained. Thus, in addition to the above-mentioned effects, since
the bonding surface is placed on the side, the foaming
magnification of the surface occupying most of the surface area can
be made higher, thereby improving the thermal insulating property
and making the suck efficiency higher. Moreover, when the core-back
is used, by enlarging the die vertical to the surface where the
projection area is large, it is possible to make the foaming
magnification of the wide surface higher and improve the thermal
insulating property and consequently make the suck efficiency
higher.
[0044] In another aspect of the present invention, since the plate
thicknesses of the corner of the casing and the portion having the
high curvature are relatively larger than the other portions, the
flow resistance of the resin at the time of the molding is dropped.
Thus, in addition to the above-mentioned effects, since the molding
is possible at the low pressure, the growth of the bubble through
the foaming gas is impelled, and since the foaming magnification is
made higher to consequently make the thermal insulating property
higher, the loss caused by the heat reception is dropped.
[0045] In another aspect of the present invention, the suction
muffler includes a sound attenuation space formed inside the
casing, a first linkage path to link the compression element and
the sound attenuation space, and a second linkage path to link the
hermetic vessel and the sound attenuation space, and wherein a wall
of the casing, which is close to at least one of the motor element,
the compression element, an open end within the sound attenuation
space of the first linkage path, and an open end within the sound
attenuation space of the second linkage path is designed so as to
have at least one of the configuration that it is thicker than the
other walls of the casing and the configuration that it is higher
in foaming magnification. Thus, the heat-exchange between the heat
source residing inside the hermetic vessel and the low temperature
refrigerant sucked into the suction muffler can be suppressed
effectively under the small volume. Hence, in addition to the
above-mentioned effects, it is possible to effectively make the
suck efficiency higher under the small volume.
[0046] In another aspect of the present invention, the lubricating
oil is stored in the hermetic vessel, and at least one of the walls
of the casing of the suction muffler to which the lubricating oil
is supplied is designed so as to have at least one of the
configuration that it is thicker than the other walls of the casing
and the configuration that it is higher in foaming magnification.
Thus, the heat-exchange at a wall of the suction muffler, where the
lubricating oil of a high temperature flows, is effectively
suppressed. Hence, in addition to the above-mentioned effects, it
is possible to effectively make the suck efficiency higher under
the small volume.
[0047] In another aspect of the present invention, the casing of
the suction muffler has a suction muffler body and a suction
muffler cover, and the bonding portion between the suction muffler
body and the suction muffler cover has the foaming magnification
that is relatively lower as compared with the portions except the
bonding portion, or it is not foam-molded. Since the vibration
absorption effect through the bubble is suppressed, in addition to
the above-mentioned effects, the bonding strength can be made
higher.
[0048] In another aspect of the present invention, the linkage path
to link the inner portion of the hermetic vessel and the sound
attenuation space of the suction muffler is formed integrally with
the farthest element from the motor element, among the plurality of
elements constituting the casing of the suction muffler. Thus, in
addition to the above-mentioned effects, the number of the parts is
reduced to reduce the cost. Also, by placing the surface having the
low thermal insulating performance on the side far away from the
motor element, the thermal insulating performance is made higher as
the entire suction muffler, and the loss caused by the heat
reception is reduced.
[0049] In another aspect of the present invention, a part of the
casing of the suction muffler is interposed between the cylinder
head and the valve plate, which constitute the compression element,
and the interposed part of the casing has the relatively low
foaming magnification, or it is not foam-molded. Thus, the strength
of the engaged portion is held, which enables the muffler to be
surely held. Hence, in addition to the above-mentioned effects, the
occurrence of an abnormal tone and the like can be protected.
[0050] In another aspect of the present invention, a part of the
casing of said suction muffler is interposed between the cylinder
head and the valve plate which constitute said compression element,
and the thickness of said interposed part of said casing is thicker
than the other portions. Thus, the strength of the engaged portion
is held, which enables the muffler to be surely held. Hence, in
addition to the above-mentioned effects, the occurrence of an
abnormal tone and the like can be protected.
[0051] In another aspect of the present invention, at a rotation
number including a rotation number less than a commercial power
supply frequency or less, the motor element is inverter-driven,
which absorbs the noise associated with the fast pulsation flow of
the refrigerant at the time of the fast rotation number operation
where the refrigerant circulation quantity is great. Thus, in
addition to the above-mentioned effects, the noise can be further
reduced.
[0052] In another aspect of the present invention, the rotation
number is 20 r/sec or less, which consequently suppresses the
heat-exchange between the low temperature refrigerant gas sucked
into the suction muffler and the heat source, such as the high
temperature refrigerant gas and the like, inside the hermetic
vessel when the low rotation number operation causes the drop in
the refrigerant flow velocity. Thus, in addition to the
above-mentioned effects, the suck efficiency can be further
reduced.
[0053] In another aspect of the present invention, since the
refrigerant gas compressed by the compression element is R600a, the
refrigerant circulation quantity is increased, and the noise of the
high frequency in the audible region associated with the fast
pulsation flow of the refrigerant gas is absorbed. Thus, in
addition to the above-mentioned effects, the noise can be further
reduced.
[0054] Another aspect of the present invention is a manufacturing
method of a suction muffler, which foam-molds at least a part of a
casing of a suction muffler made of synthetic resin for a hermetic
compressor, wherein in the molding course, a core-back is used to
move a part of a die, enlarge a cavity and make a plate thickness
thicker. Then, by enlarging the die, the pressure is dropped and
the gas is expanded, thereby impelling the foaming. Thus, in
addition to the above-mentioned effects, since the higher foaming
magnification is obtained, the excellent thermal insulating
performance is obtained, thereby enabling the suck efficiency to be
made higher.
[0055] Another embodiment of the present invention is a
manufacturing method of a suction muffler, which foam-molds at
least a part of a casing of a suction muffler made of synthetic
resin for a hermetic compressor, wherein a section area of a gate
serving as a resin supplying portion to cavities inside a die is
equal to or greater than 70% of a square of a plate thickness of
the casing. Thus, since the resistance when the resin flows from
the gate is dropped, in addition to the above-mentioned effects,
the molding is possible under the low pressure, which impels the
growth of the bubble through the foamed gas. Then, by making the
foaming magnification higher and making the foaming magnification
higher, the loss caused by the heat reception is reduced.
[0056] Another embodiment of the present invention is a
manufacturing method of a suction muffler, which foam-molds at
least a part of a casing of a suction muffler made of synthetic
resin for a hermetic compressor, wherein two or more gates serving
as resin supplying portions to cavities inside a die are installed
for at least one unit. Thus, the installation of the plurality of
gates causes the resin to be easily permeated into the die. Hence,
in addition to the above-mentioned effects, the molding is possible
under the low pressure, which impels the growth of the bubble
through the foamed gas. Then, by making the foaming magnification
higher and making the foaming magnification higher, the loss caused
by the heat reception is reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0057] FIG. 1 is a sectional view of a hermetic compressor in a
first embodiment 1 of the present invention;
[0058] FIG. 2 is a sectional view of a suction muffler in the same
embodiment;
[0059] FIG. 3 is an enlarged sectional view of a wall A portion in
FIG. 2;
[0060] FIG. 4 is a main portion sectional view of a corner of the
hermetic compressor in the same embodiment;
[0061] FIG. 5A is a schematic configuration view of a foam molding
machine in the same embodiment;
[0062] FIG. 5B is a schematic configuration view of a foam molding
machine in the same embodiment;
[0063] FIG. 5C is a schematic configuration view of a foam molding
machine in the same embodiment;
[0064] FIG. 6 is a front view showing a suction muffler body and a
runner in the same embodiment;
[0065] FIG. 7 is a sectional view of a suction muffler in a second
embodiment of the present invention;
[0066] FIG. 8 is an enlarged view of a foaming portion of the
suction muffler in the same embodiment;
[0067] FIG. 9 is a rear view of a suction muffler body in the same
embodiment;
[0068] FIG. 10 is a decomposed perspective view of the suction
muffler in the same embodiment;
[0069] FIG. 11 is an enlarged view of a bonded section between a
cover and the suction muffler in the same embodiment;
[0070] FIG. 12A is a schematic configuration view of a
supercritical foam molding machine in the same embodiment;
[0071] FIG. 12B is a schematic configuration view of a
supercritical foam molding machine in the same embodiment;
[0072] FIG. 12C is a schematic configuration view of a
supercritical foam molding machine in the same embodiment;
[0073] FIG. 13 is a sectional view of a hermetic compressor in a
third embodiment of the present invention;
[0074] FIG. 14 is a decomposition view of a suction muffler in the
same embodiment;
[0075] FIG. 15A is a schematic configuration view of a
supercritical foam molding machine in the same embodiment;
[0076] FIG. 15B is a schematic configuration view of a
supercritical foam molding machine in the same embodiment;
[0077] FIG. 15C is a schematic configuration view of a
supercritical foam molding machine in the same embodiment;
[0078] FIG. 16 is a decomposition view of a suction muffler in a
fourth embodiment of the present invention;
[0079] FIG. 17 is a sectional view of a conventional hermetic
compressor;
[0080] FIG. 18 is a sectional view of a suction muffler in the
conventional hermetic compressor;
[0081] FIG. 19 is a flow velocity vector view inside the suction
muffler of the conventional hermetic compressor; and
[0082] FIG. 20 is a sectional view of the suction muffler in the
conventional hermetic compressor.
BEST MODE FOR CARRYING OUT THE INVENTION
[0083] An embodiment of the present invention will be described
below with reference the drawings. By the way, this embodiment does
not limit the present invention.
First Embodiment
[0084] FIG. 1 is a sectional view of a hermetic compressor in the
first embodiment of the present invention, and FIG. 2 is a
sectional view of a suction muffler of the hermetic compressor in
the same embodiment. FIG. 3 is an enlarged sectional view of a wall
A-portion in FIG. 2. FIG. 4 is a main portion sectional view of a
corner in the suction muffler in the same embodiment. FIGS. 5A to
5C are schematic configuration views of a foam molding machine in
the same embodiment. FIG. 6 is a front view showing a suction
muffler body and a runner in the same embodiment.
[0085] In FIG. 1, a hermetic vessel 101 accommodates: a motor
element 105 composed of a rotator 104 and a stator 103 holding a
coil portion 102; and a compression element 106 driven by the motor
element 105. A lubricating oil 108 is stored in the hermetic vessel
101. By the way, as refrigerant gas (not shown), R600a of natural
refrigerant is used.
[0086] Also, the motor element 105 is driven by an inverter method
including a rotation number of 20 r/sec or less.
[0087] The schematic configuration of the compression element 106
will be described below.
[0088] A crank shaft 110 has: a main shaft portion 111 where the
rotator 104 is press-fitted and fixed; and an eccentric portion 112
formed eccentrically to the main shaft portion 111. Inside the main
shaft portion 111, an oil pump 113 is placed so as to be opened in
the lubricating oil 108.
[0089] A cylinder block 120 formed above the motor element 105 has:
a compression room 122 that is approximately cylindrical; and a
shaft supporter 123 that supports the main shaft portion 111 with a
shaft. A piston 130 is inserted into the compression chamber 122 of
the cylinder block 120 so as to be reciprocatingly slidable
therein, and linked to the eccentric portion 112 by a linking
device 131.
[0090] A valve plate 135 for sealing the open end surface of the
compression room 122 has a suck hole 138 to be linked to the
compression room 122 in accordance with the opening/closing action
of a suction valve 134. A cylinder head 136 is fixed through the
valve plate 135 to the opposite side to the compression room 122. A
suction tube 137 is fixed to the hermetic vessel 101 and connected
to the low pressure side (not shown) of a freezing cycle, and
introduces the refrigerant gas (not shown) into the hermetic vessel
101.
[0091] A suction muffler 140 is fixed because it is interposed
between the valve plate 135 and the cylinder head 136, and it is
made of synthetic resin, such as polybutylene telephthalate and the
like, to which glass fiber is mainly added.
[0092] Moreover, the suction muffler 140 has: a casing 140C
composed of a plurality of walls; a first linkage path 145 and a
second linkage path 146, and a sound attenuation space 143 is
formed inside the casing 140C. Inside a wall 147 of the casing 140C
of the suction muffler 140 which is close and opposite to open ends
145a, 146a within the sound attenuation space, in order to generate
innumerable bubbles 150 of about 100 .mu.m at a bubbling
magnification of 1.2 times or more, a non-foaming skin layer 151
where a plate thickness is 3 to 5 mm and thicker than the other
portions and bubbles are not contained in the vicinity of the
surface is formed.
[0093] Moreover, the thicknesses E, F of the skin layer are about
10 to 20% of a plate thickness G. Then, a plate thickness B of a
corner 140a of the casing 140C of the suction muffler 140 is
thicker than the plate thicknesses C, D of a flat portion.
[0094] By the way, the bubble 150 made by a foaming resin molding
(which will be described later in detail) is generated at the size
of a bubble density of about 10.sup.7 cells/cm.sup.3 and a bubble
diameter of about 100 .mu.m by adjusting the thickness of the wall
and the molding temperature and molding pressure at the time of the
foam molding. Due to the thermal insulation effect of the bubble
150, the thermal insulation performance improvement of about 5 to
10% is attained as compared with a non-foaming solid material.
[0095] On the other hand, as shown in FIGS. 5A to SC, an injection
molder 170 is provided with a raw material inserter 171, a fusion
injector 172, a die unit 177, a controller (not shown) for
controlling the drive of the die unit 177 and the cooling
temperature and the like and adjusting the bubble density and the
bubble diameter.
[0096] The molding process for the foaming resin by using the
injection molder 170 will be described below.
[0097] At first, as shown in FIGS. 5A to 5C, the raw material
pellet of polybutylene telephthalate and the pellet of the chemical
foaming agent such as azo compound represented by azodicalbonamide
and the like are thrown into the raw material inserter 171. The
thrown into raw material pellet and foaming agent pellet are fused
at a temperature of about 250.degree. C. or more in the fusion
injector 172, mixed by a screw 175 built in the fusion injector
172, squeezed by the screw 175 and injected into the die unit
177.
[0098] Then, as shown in FIG. 6, the fused resin supplied into the
die unit 177 from a sprue 181 is passed through a runner 182
serving as a flowing path and supplied to a plurality of cavities
183 having the shapes of the molded products which are formed
inside the die. Two gates 185, 186 serving as the inlets of the
resin to the cavities 183 are placed for one part. They are
selected such that the section areas of the gates 185, 186 are
thinner than the runner 182, the thicknesses are 30 to 40% of the
wall thickness, and the widths are about three times the
thicknesses.
[0099] As for the fused resin flowing into the cavities 183 from
the gates 185, 186, the friction when it is passed through the
gates 185, 186 causes the increase in the temperature and the drop
in the pressure. In association with the chemical reaction and the
like, the mixed fused foaming agent is gasified within the cavity
183, and it becomes the foaming gas in the fused raw material, and
the bubble is generated.
[0100] On the other hand, since the die unit 177 has the structure
cooled by gas and liquid, the raw material and foaming gas which
are injected into the cavities 183 defined by the die unit 177 are
cooled to a constant temperature and consequently molded. At this
time, the controller adjusts the injection quantities and injection
temperatures of the raw material and foaming agent and the cooling
temperature of the die unit 177 and the like, and controls the
temperature and pressure at the time of the molding. Thus, it is
possible to arbitrarily adjust the bubble density and bubble
diameter of the foaming resin.
[0101] Concretely, the high foaming magnification can be obtained
by setting the quantity of the fusion resin injected into the
cavities 183 defined by the die unit 177 to be smaller than the
volume of the cavities 183, and filling the remaining space with
the expansion through the foaming.
[0102] Moreover, the fusion resin is high in viscosity. Thus, when
the fusion resin flows through the cavities 183 defined by the die
unit 177, the flow is the fastest at the center of the plate
thickness of the molded member. As it approaches the surface of the
die unit 177, the velocity becomes slower. The region where the
resin does not substantially flow appears in the very vicinity of
the surface of the die unit 177.
[0103] For this reason, the fusion resin is sharply cooled because
it is adhered closely to the die unit 177 of the low temperature at
the substantially static state. Thus, on the surface of the die
unit 177, the resin is hardened before the formation of the bubble.
Hence, the skin layer is formed in which the bubble does not exist
substantially.
[0104] Thus, as the plate thickness becomes thinner, the rate of
the layer having the bubbles generated between the skin layer and
the skin layer becomes small, which leads to the situation that as
a whole, the bubble is little and the thermal insulation property
is low.
[0105] However, as already explained, by setting the plate
thickness of the wall of the suction muffler 140, which is close
and opposite to the open ends 145a, 146a within the sound
attenuation space, to 3 to 5 mm that is thicker than the plate
thicknesses of the other walls, the thicknesses E, F of the skin
layers can be limited to about 10 to 20% of the plate thickness G,
and by setting the foaming magnification at about 1.2 times at the
weight ratio to the solid member, the thermal insulation property
can be partially improved.
[0106] Also, as can be easily understood from the mechanism of the
formation of the skin layer, as the plate thickness is thinner, the
gap where the fusion resin can actually flow becomes extremely
narrower, and the resistance against the flow of the fused resin is
increased.
[0107] On the other hand, the pressure caused by the foaming gas is
relatively weak. Thus, if there is the portion having the large
resistance, the resin does not sufficiently flow. Hence, the
cavities 183 defined by the die unit 177 cannot be filled with the
resin. Reversely, in order to avoid the lack of the filling, the
large quantity of the resin is injected at the high pressure, which
results in the drop in the foaming magnification.
[0108] On the contrary, as shown in FIG. 4, by increasing the
thickness of the corner 140a of the die where the resistance
becomes especially easily large, it is possible to make the foaming
magnification higher, and possible to make the thermal insulation
property higher. Also, due to the supply of the resin from the two
gates 185, 186, even in the case of the die where the plate
thickness is thin and the flow resistance is large, even at the low
pressure, it is easy to fill the resin in the entire die, which
enables the foaming magnification to be higher and enables the
thermal insulating property to be higher.
[0109] Moreover, by adjusting the position of the gate, the plate
thickness of the part and the die temperature, it is also possible
to adjust the foaming magnification for each portion.
[0110] The operation of the hermetic compressor in this embodiment
having the above-mentioned configuration is explained.
[0111] The refrigerant gas introduced into the hermetic vessel 101
by the reciprocating motion of the piston is sucked from the
suction muffler 140, and released to the sound attenuation space
143 from the open end 146a within the sound attenuation space. The
released refrigerant gas collides with the wall 147 of the casing
140C of the suction muffler 140 which is close and opposite to the
open end 146a within the sound attenuation space, and then
circulates through the sound attenuation space 143. After that, the
refrigerant gas mainly circulating through the upper portion is
sucked to the first linkage path 145 from the open end 145a within
the sound attenuation space, and compressed in the compression room
122 and discharged to the cooling system.
[0112] Here, in order to reserve the foaming magnification of 1.2
times or more only for the wall 147 of the casing of the suction
muffler 140 where the main flow of the refrigerant gas flowing from
the open end 146a within the sound attenuation space into the open
end 145a within the sound attenuation space is generated, the plate
thickness is set to 3 to 5 mm, thereby obtaining the thermal
insulating effect which is partially high consequently, as compared
with the case of foam-molding the suction muffler 140 as a whole,
it is possible to obtain the effective thermal insulating effect at
the small volume.
[0113] As a result, the action for maintaining the refrigerant gas
at the state of the low temperature and high density can be
effectively made higher, thereby increasing the mass flow quantity
of the refrigerant gas. In particular, at the low operation
rotation number of 20 r/sec or less where the flow velocity of the
refrigerant gas is dropped and the stay time of the refrigerant gas
within the suction muffler 140 is longer, the reduction effect of
the loss caused by the heat reception is extremely large.
[0114] Due to the suppression of the temperature increase in the
refrigerant gas as mentioned above, the temperature increase
between the open end 146a within the sound attenuation space and
the open end 145a within the sound attenuation space can be
suppressed to 2K or less. Thus, the freezing performance is
improved by 1.5% as compared with the conventional suction muffler
specification, and the efficiency (hereafter, referred to as COP)
is improved by 1.0% or more.
[0115] On the other hand, the refrigerant gas within the suction
muffler 140 becomes the intermittent flow corresponding to the
reciprocating motion of the piston 130. At this time, the pressure
pulsation is propagated in the direction opposite to the flow of
the refrigerant gas, towards the open end 145a within the sound
attenuation space, and a reflection wave is generated towards the
wall 147 which is close and opposite to the open end 145a within
the sound attenuation space.
[0116] For this reflection wave, the vibration loss caused by the
vibration of the wall member itself constituting the casing of the
suction muffler 140 and the vibration energy caused by the friction
between the gas within the bubble and the material around the
bubble are absorbed, which can increase the acoustic transmission
loss. In particular, it is confirmed that this has the effect on
the transmission sound reduction in the high frequency component in
an audible region.
[0117] In particular, since this embodiment uses R600a that is the
natural refrigerant, the refrigerant circulation quantity is
increased as compared with the case of R134a. Thus, the pulsation
flow of the refrigerant gas sucked into the suction muffler 140 is
fast, which easily induces the noise of the high frequency. That
tendency severely appears in the rotation number of a commercial
power supply frequency or more. For this phenomenon, since the wall
147 that is close and opposite to the open end 145a within the
sound attenuation space to which the reflection wave is radiated is
foam-molded, the effect of reducing the noise in the audible region
is extremely higher.
[0118] Also, since the suction muffler 140 uses the polybutylene
telephthalat that is the crystal synthetic resin, its chemical
resistance is strong. The resin is not substantially fused in the
refrigerant and the lubricating oil 108, which improves the
reliability and enables the stable operation of the compressor.
[0119] Also, the skin layer 151 where the bubble does not exist is
formed in the vicinity of the surface of the wall 147 where the
suction muffler 140 is foam-molded. Thus, the refrigerant and the
lubricating oil 108 are never permeated into the inner space of the
suction muffler 140, which improves the reliability and enables the
stable operation of the compressor.
[0120] Moreover, by setting the foaming magnification to about 1.2
times, as compared with the case of using the solid material of the
non-foaming resin and forming the suction muffler of the same
shape, it is possible to reduce the usage quantity of the resin
material, and possible to rationalize the raw material cost.
[0121] Thus, it is possible to reduce the loss caused by the heat
reception and make the suck efficiency higher and also possible to
reduce the noise, and possible to improve the reliability and carry
out the stable operation.
Second Embodiment
[0122] FIG. 7 is a sectional view of a suction muffler of a
hermetic compressor in the second embodiment of the present
invention, and FIG. 8 is an enlarged view of a foaming portion of
the suction muffler in the same embodiment. FIG. 9 is a rear view
of a suction muffler body in the same embodiment, FIG. 10 is a
decomposed perspective view of the suction muffler of the hermetic
compressor in the same embodiment, and FIG. 11 is an enlarged view
of a bonding section between a cover and the suction muffler body
in the same embodiment. FIGS. 12A to 12C are schematic
configuration views of a supercritical foam molding machine in the
same embodiment. By the way, the configuration of the hermetic
compressor in this embodiment is the same configuration as the
first embodiment except the suction muffler. Thus, the explanation
is omitted.
[0123] As shown in FIG. 7, the suction muffler 240 has a casing
240C composed of a plurality of walls, a first linkage path 245 and
a second linkage path 246, and a sound attenuation space 243 is
formed inside the casing 240C. Here, the casing 240C of the suction
muffler 240 is molded by using a supercritical foam molding (which
will be described later in detail), and the micro bubbles of bubble
diameters of 1 to 50 .mu.m resides in the entire wall except the
portions where film thicknesses are thin. Here, the bubbles 250
generated by the supercritical foam molding process are generated
at the high densities of about 10.sup.9 to 10.sup.15 cells/cm3.
Thus, as compared with the non-foaming solid material, the thermal
insulating performance can be improved by about 20% or more. Here,
bubbles 250 are formed inside the walls of the casing 240C.
Although not shown, the surfaces on the walls of the casing 240C
are covered by the skin layer where the bubbles 250 do not
exist.
[0124] Also, as shown in FIG. 9, a suction muffler body 241
constituting the main portion of the casing 240C has: a lubricating
oil supplying path 252 formed in the shape of a rib on the outer
surface of the suction muffler body 241 so as to send the
lubricating oil 108; and a lubricating oil supplying hole 253 to
suck the lubricating oil into the suction muffler 240 from the
lubricating oil supplying path 252.
[0125] On the other hand, after the first linkage path 245 is
inserted and assembled into the suction muffler body 241, a welding
protrusion 245b is positionally matched with a hole 242b of a suck
muffler cover 242. After that, the suction muffler body 241 and the
suck muffler cover 242 are bonded by using a supersonic welding
method and the like, and the suction muffler 240 is completed.
[0126] Here, the suction muffler 240 is configured so as to be
bonded by a body side bonding portion 254 formed around the suction
muffler body 241 and a cover side bonding portion 255 formed around
the suck muffler cover 242. The plate thicknesses of the body side
bonding portion 254 and cover side bonding portion 255 are both
designed so as to be equal to or less than the basic wall thickness
of the casing 240C of the suction muffler 240.
[0127] By the way, a supercritical foam molding machine 270 used to
mold the suction muffler 240 in this embodiment is provided with a
raw material inserter 271, a supercritical gas generator 274, a
fusion injector 272, a die unit 277 and a controller (not shown)
for controlling the drive of the die unit 277 and the cooling
temperature, as shown in FIGS. 12A to 12C. Since the inactive gas,
such as carbon dioxide, nitrogen and the like, is used without
using the foaming agent, such as azo-compound, flon and the like,
which is environmental load substance, the environmentally friendly
molding is executed.
[0128] The molding process for the foaming resin using the
supercritical foam molding machine 270 will be described below.
[0129] At first, the raw material pellet of the polybutylene
telephthalate is thrown into the raw material inserter 271. The
thrown into raw material pellet is fused at a temperature of about
250.degree. C. or more in the fusion injector 272. On the other
hand, the carbon dioxide or nitrogen of the physical foaming agent
which becomes at the supercritical state in the supercritical gas
generator 274 is injected into the fusion injector 272, and mixed
as the high pressure solution with resin raw material by a screw
275. After that, together with the raw material fused by the screw
275, the foaming agent at the supercritical state is injected to
the die unit 277.
[0130] Then, the sharp volume change and temperature change, which
are induced at the time of the injection to the die unit 277, cause
the foaming agent at the supercritical state to be gasified,
thereby generating the bubble. At this time, the controller adjusts
the injection quantities and injection temperatures of the raw
material and foaming agent, and the pressure, and the temperature
of the die unit 277 and the like, and controls the temperature and
pressure at the time of the molding. Thus, it is possible to
arbitrarily adjust the bubble density and bubble diameter of the
foaming resin.
[0131] Moreover, the fusion resin is high in viscosity. Thus, when
the fusion resin flows through the die unit 277, the flow is the
fastest at the center of the plate thickness. As it approaches the
surface of the die unit 277, the velocity becomes slower. The
region where the resin does not substantially flow appears in the
very vicinity of the surface of the die unit 277. Thus, the fusion
resin is sharply cooled because it is adhered closely to the die
unit 277 of the low temperature at the substantially static state.
Thus, on the surface of the die unit, the resin is hardened before
the formation of the bubble. Hence, the skin layer is formed in
which the bubble does not exist substantially.
[0132] The operation of the hermetic compressor configured as
mentioned above will be described below.
[0133] In this embodiment, the carbon dioxide and nitrogen at the
supercritical state melted into the resin material at the fused
state are gasified in response to the change in the temperature and
pressure, which enables the generation of the very micro bubbles of
the diameters of 1 to 50 .mu.m.
[0134] As a result, the micro bubbles are generated on all of the
walls without any change in the basic design dimensions of the
suction muffler 240. Thus, it is possible to improve the thermal
insulating performances of all of the walls close to the high
temperature heat source, such as the rear side wall of the suction
muffler body 241 where the motor element 105 is located and the
lubricating oil supplying path 252 is formed, the vicinity of the
open end linked to the compression element 106, the wall which is
close and opposite to the open end 246a within the sound
attenuation space where the low temperature refrigerant gas sucked
into the suction muffler 240 is released to the sound attenuation
space 243, and the like.
[0135] As a result, the heat reception of the refrigerant gas of
the low temperature sucked into the suction muffler 240 can be
largely decreased, thereby maintaining the density of the
refrigerant gas low and increasing the mass flow quantity of the
sucked refrigerant gas.
[0136] As the above-mentioned result, the drop in the loss caused
by the heat reception from the refrigerant gas enables the increase
in the suck efficiency. As compared with the conventional example,
the freezing performance is improved by 2.5%, and the COP is
improved by 2.0% or more.
[0137] On the other hand, due to the improvement effect of the
acoustic transmission loss caused by the innumerable bubbles
generated so as to cover the whole of the suction muffler 240, the
noise vibration caused by the pulsation flow and the reflection
flow radiated to the wall of the close opposite casing from the
open end 245a within the sound attenuation space is largely
reduced. In particular, this has the effect on the transmission
sound drop of the high frequency component in the audible
region.
[0138] Moreover, the usage of the supercritical foam molding
technique in this embodiment enables the micro independent bubbles
to be generated on all of the walls of the suction muffler 240.
Thus, without substantially decreasing the mechanical strength of
the material and by setting the foaming magnification to 1.2 times
or more, it is possible to reduce the usage quantity of the raw
material by 20% or more, and possible to rationalize the raw
material cost.
[0139] Also, in the body side bonding portion 254 and cover side
bonding portion 255 of the suction muffler body 241, by making the
wall thickness thinner than the basic wall thickness, it is
possible to suppress the generation of the bubbles, suppress the
vibration drop effect in the bonding portion and carry out the idea
to keep the bonding strength through the vibration of the
supersonic welding.
[0140] By the way, in this embodiment, the wall thickness is
thinner than the basic wall thickness in the body side bonding
portion 254 and the cover side bonding portion 255. However, by
making the wall thickness equal to or thicker than the basic wall
thickness and making the bubbles reside in all of the walls of the
suction muffler 240, it is natural to further reduce the light
reception from the refrigerant gas.
[0141] Also, in this embodiment, the explanation of the
specification overlapping with the first embodiment is omitted.
However, the improvement of the reliability resulting from the
chemical resistance of the crystal synthetic resin and the
permeation protection effect of the refrigerant and lubricating oil
through the skin layer, and the effect of the operational
stabilization of the compressor can be similarly obtained even in
this embodiment.
[0142] Also, the noise drop effect in the audible region in
association with the fast pulsation flow of the refrigerant gas in
the high rotation number, and the heat reception drop effect within
the suction muffler 240 in association with the low velocity flow
of the refrigerant gas in the low rotation number of the 20 r/sec
or less can be made higher as compared with the first
embodiment.
Third Embodiment
[0143] FIG. 13 is a sectional view of a hermetic compressor in the
third embodiment of the present invention, and FIG. 14 is a
decomposition view of a suction muffler in the same embodiment.
FIGS. 15A to 15C are schematic configuration views of a
supercritical foam molding machine in the same embodiment. By the
way, the configuration of the hermetic compressor in this
embodiment is the same configuration as the second embodiment,
except the suction muffler. Thus, the explanation is omitted.
[0144] A suction muffler 340 is composed of three parts of a motor
element side 341, an anti-motor element side 342 and a center 343.
Most of the portions of their elements constitute a casing 340C.
The suction muffler 340 where the three parts of the motor element
side 341, the anti-motor element side 342 and the center 343 are
combined has a first linkage path 345 and a second linkage path
346, and a sound attenuation space 347 is formed inside the casing
340C. Also, the first linkage path 345 is formed on the bonding
surface between the center 343 and the anti-motor element side 342,
and the second linkage path 346 is formed integrally with the part
of the anti-motor element side 342.
[0145] Moreover, the suction muffler 340 is interposed between the
cylinder head 136 and the valve plate 135, and the thickness of
this engaged portion is thicker than the other portions.
[0146] Also, the above-mentioned configuration elements (including
the casing 340C) of the suction muffler 340 are molded by using the
supercritical foam molding. In particular, the supercritical foam
molding which uses core-back is performed on the motor element side
341.
[0147] The molding process for the foaming resin which uses the
core-back in a supercritical foam molding machine 370 will be
described below.
[0148] At first, the raw material pellet of the polybutylene
telephthalate is thrown into a raw material inserter 371. The
thrown into raw material pellet is fused at the temperature of
about 250.degree. C. or more in a fusion injector 372. On the other
hand, the carbon dioxide or nitrogen of the physical foaming agent
which becomes at the supercritical state in the supercritical gas
generator 374 is injected into the fusion injector 372, and mixed
as the high pressure solution with the resin raw material by a
screw 375. After that, together with the raw material fused by the
screw 375, the foaming agent at the supercritical state is injected
into a die unit 377. The processes until this are similar to the
second embodiment.
[0149] Then, because of the sharp volume change and temperature
change which are induced in the passage through the gate at the
time of the injection to the cavity inside the die unit 377, the
foaming agent at the supercritical state is gasified, thereby
generating the bubble. However, it is selected that the thickness
of the gate portion is 60% of the wall thickness and that the width
is about three times the thickness. The section area is
approximately equal to the square of the wall thickness. As
compared with the first embodiment, the area becomes wider, such as
two times.
[0150] Thus, the section area of the gate portion is wider than the
second embodiment, and the flow behavior of the resin is excellent.
Hence, while the gas pressure of the physical foaming agent is kept
high, in the situation that the bubble is small, the fused resin is
filled into the cavity.
[0151] After that, a part 377a of the die unit is retreated in an
arrow direction, and the core-back is executed to enlarge the space
of the cavity. Thus, the pressure inside the cavity is dropped, and
the bubble is expanded. Hence, the foaming magnification is
increased to 30 to 40% that exceeds the supercritical foaming in
which the core-back is not used. As a result, the thermal
insulating property of the casing 340C of the suction muffler 340
can be further improved, thereby improving the performance.
[0152] By the way, the suction muffler 340 is separated and divided
in the direction approximately vertical to the wall where the
maximum projection area is obtained. Moreover, the direction where
at the time of the molding, the part of the die unit is moved-to
enlarge the cavity is the projection direction where the maximum
projection area of the suction muffler 340 is obtained. As a
result, enlarging the thickness of the surface having the largest
area increases the improvement effect of the thermal insulating
performance and the foaming magnification through the core-back,
and improves the suck efficiency. Here, the maximum projection area
implies the maximum projection area obtained when the projections
from various directions are performed on the targeted member.
[0153] Also, although the core-back contributes to the improvement
of the thermal insulating performance, the application to the
complex part into which a pipe and the like are integrated is
difficult. However, according to this embodiment, the motor element
side 341 close to the compression element 106 and the motor element
105 serving as the heat source is configured such that the
relatively simple surface is main and the core-back can be
effectively applied, thereby attaining the efficiency improvement.
On the other hand, the second linkage path 346 is molded integrally
with the anti-motor element side 342 on the opposite side.
Consequently, the number of the parts is reduced to reduce the
cost.
[0154] In the case of using the supercritical foaming technique,
the drop in the strength caused by the foaming is low as compared
with the conventional foaming technique. However, as the foaming
magnification is higher, the strength is further dropped.
Incidentally, since the suction muffler 340 is fixed, in the
portion interposed between the valve plate 135 and the cylinder
head 136, by making the plate thickness relatively thicker, the
strength can be reserved, thereby protecting the occurrence of the
abnormal tone caused by the vibration of the suction muffler 340
and the leakage of the gas.
Fourth Embodiment
[0155] FIG. 16 is a decomposition view of a suction muffler of a
hermetic compressor in the fourth embodiment of the present
invention. By the way, the configuration of the hermetic compressor
in this embodiment is the same configuration as the third
embodiment except the suction muffler, and the method of the
supercritical foam molding is also similar. Thus, the explanation
is omitted.
[0156] In FIG. 16, a casing 440C of a suction muffler 440 is
constituted by two parts of a suction muffler body 441 and a
suction muffler cover 442 and assembled by a method of welding and
the like. Also, since the suction muffler cover 442 is interposed
between the cylinder head 136 and the valve plate 135, the suction
muffler 440 is fixed.
[0157] The suction muffler cover 442 has the sufficient strength,
because the foam molding is not executed. Thus, it is possible to
protect the occurrence of the abnormal tone caused by the vibration
of the suction muffler 440 and the leakage of the gas.
[0158] On the other hand, the suction muffler body 441 is
manufactured by the supercritical foam molding, similarly to the
third embodiment. Moreover, the core-back is carried-out in the
projection direction where the maximum projection area is obtained
as shown by an arrow of FIG. 16. Consequently, a plate thickness H
of the wall, which occupies most of the surface area of the casing
440C of the suction muffler 440 and is close to the motor element
105 of the high temperature and the like, is made thicker than a
plate thickness I of the other walls, and the foaming magnification
is made higher. Thus, the thermal insulating performance of the
whole of the suction muffler 440 is improved, thereby improving the
suck efficiency.
INDUSTRIAL APPLICABILITY
[0159] As mentioned above, the hermetic compressor according to the
present invention and the manufacturing method of the suction
muffler can make the suck efficiency higher and also reduce the
noise vibration. Thus, they can be applied to the usage field, such
as the air condition, the freezing refrigerating apparatus or the
like.
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