U.S. patent application number 14/276479 was filed with the patent office on 2014-11-20 for compressor.
This patent application is currently assigned to KABUSHIKI KAISHA TOYOTA JIDOSHOKKI. The applicant listed for this patent is KABUSHIKI KAISHA TOYOTA JIDOSHOKKI. Invention is credited to Osamu HIRAMATSU, Takahiro HOSHIDA, Hiroaki KAYUKAWA, Noriyuki SHINTOKU, Masahiro SUZUKI, Yasushi SUZUKI.
Application Number | 20140341766 14/276479 |
Document ID | / |
Family ID | 50628690 |
Filed Date | 2014-11-20 |
United States Patent
Application |
20140341766 |
Kind Code |
A1 |
HOSHIDA; Takahiro ; et
al. |
November 20, 2014 |
COMPRESSOR
Abstract
A compressor has therein a suction chamber into which
refrigerant gas is introduced, a compression chamber in which the
refrigerant gas in the suction chamber is introduced and
compressed, and a discharge chamber into which the compressed
refrigerant gas is discharged from the compression chamber. The
suction chamber and the discharge chamber are formed adjacent to
each other while being separated by a partition wall. At least one
surface of the partition wall is provided with a thermal insulator
which is formed by curing a thermal insulation coating composition.
The thermal insulator includes hollow beads and one or more binder
resin selected from the group consisting of epoxy resin,
polyamide-imide resin, phenolic resin, and polyimide resin.
Inventors: |
HOSHIDA; Takahiro;
(Kariya-shi, JP) ; KAYUKAWA; Hiroaki; (Kariya-shi,
JP) ; SHINTOKU; Noriyuki; (Kariya-shi, JP) ;
SUZUKI; Masahiro; (Kariya-shi, JP) ; HIRAMATSU;
Osamu; (Kariya-shi, JP) ; SUZUKI; Yasushi;
(Kariya-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KABUSHIKI KAISHA TOYOTA JIDOSHOKKI |
Aichi-ken |
|
JP |
|
|
Assignee: |
KABUSHIKI KAISHA TOYOTA
JIDOSHOKKI
Aichi-ken
JP
|
Family ID: |
50628690 |
Appl. No.: |
14/276479 |
Filed: |
May 13, 2014 |
Current U.S.
Class: |
417/539 |
Current CPC
Class: |
F04B 39/06 20130101;
F05C 2251/048 20130101; F05C 2225/10 20130101; F04B 27/1036
20130101; F05C 2225/06 20130101; F05C 2253/12 20130101; F05C
2253/20 20130101; F04B 39/121 20130101; F05C 2251/10 20130101; F04B
27/1081 20130101 |
Class at
Publication: |
417/539 |
International
Class: |
F04B 39/12 20060101
F04B039/12 |
Foreign Application Data
Date |
Code |
Application Number |
May 16, 2013 |
JP |
2013-103709 |
Claims
1. A compressor comprising: a suction chamber into which
refrigerant gas is introduced; a compression chamber in which the
refrigerant gas in the suction chamber is introduced and
compressed; and a discharge chamber into which the compressed
refrigerant gas is discharged from the compression chamber, the
suction chamber and the discharge chamber being formed adjacent to
each other while being separated by a partition wall, wherein at
least one surface of the partition wall is provided with a thermal
insulator which is made by curing a thermal insulation coating
composition, and the thermal insulator includes hollow beads and
one or more binder resins selected from the group consisting of
epoxy resin, polyamide-imide resin, phenolic resin, and polyimide
resin.
2. The compressor according to claim 1, wherein the hollow beads
have a breaking strength of 3 MPa or more.
3. The compressor according to claim 1, wherein the hollow beads
comprise a sodium aluminosilicate glass.
4. The compressor according to claim 1, the compressor using
polyalkylene glycol or polyol ester as the lubricant.
5. The compressor according to claim 1, wherein the thermal
insulator is provided at least on a surface of the partition wall
facing the discharge chamber.
6. The compressor according to claim 1, wherein the partition wall
includes a suction chamber wall disposed on the suction chamber
side and a discharge chamber wall disposed on the discharge chamber
side, the suction chamber wall and the discharge chamber wall being
disposed apart from each other and filled with the thermal
insulator therebetween.
7. The compressor according to claim 1, wherein the suction chamber
is disposed so as to surround the discharge chamber.
8. The compressor according to claim 1, the compressor being used
in a vehicle air conditioning system.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a compressor for use in an
air conditioning system.
[0002] A compressor for use in a refrigeration cycle or a heat pump
cycle of an air conditioning system compresses in a compression
chamber thereof low-temperature, low-pressure refrigerant gas
introduced into a suction chamber and discharges compressed
high-temperature, high-pressure refrigerant gas into a discharge
chamber. In order to enhance the compression efficiency of the
refrigerant gas in such compressors, various compressors have been
proposed.
[0003] For example, Japanese Unexamined Patent Application
Publication No. 2005-344654 discloses a compressor in which a
thermal insulator is provided on a part of a wall surrounding the
discharge chamber. The compressor has a partition wall between the
discharge chamber and the suction chamber and the thermal insulator
is provided on the surface of the partition wall that faces the
discharge chamber, and also on at least a part of the wall between
the discharge chamber and the outside of the compressor. With this
configuration, the temperature rise of the refrigerant gas in the
suction chamber is suppressed and the compression efficiency is
enhanced. Additionally, part of the heat of the refrigerant gas
discharged into the discharge chamber is released to the outside
and a drop in efficiency of an entire refrigeration cycle is
prevented.
[0004] However, any peel-off occurring in any part of the thermal
insulator on the inner surface of the discharge chamber may affect
the operation of the compressor and there is a fear that the
compressor may be damaged internally in some cases. Specifically,
the temperature and the pressure in the compressor increase and the
resin component contained in the thermal insulator is prone to
deterioration. Excessive deterioration of the resin component may
embrittle the thermal insulator and, in some cases, part of the
thermal insulator may peel off. The compressor should be protected
against such trouble and the thermal insulator needs to be
prevented from being peeled off for ensuring the reliability of the
compressor.
[0005] The present invention, which has been made in view of the
above circumstances, is directed to a compressor which is excellent
in compression efficiency and reliability.
SUMMARY OF THE INVENTION
[0006] In accordance with an aspect of the present invention, there
is provided a compressor which has therein a suction chamber into
which refrigerant gas is introduced, a compression chamber in which
the refrigerant gas in the suction chamber is introduced and
compressed, and a discharge chamber into which the compressed
refrigerant gas is discharged from the compression chamber. The
suction chamber and the discharge chamber are formed adjacent to
each other while being separated by a partition wall. At least one
surface of the partition wall is provided with a thermal insulator
which is formed by curing a thermal insulation coating composition.
The thermal insulator includes hollow beads and one or more binder
resins selected from the group consisting of epoxy resin,
polyamide-imide resin, phenolic resin, and polyimide resin.
[0007] Other aspects and advantages of the invention will become
apparent from the following description, taken in conjunction with
the accompanying drawings, illustrating by way of example the
principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The invention together with objects and advantages thereof,
may best be understood by reference to the following description of
the presently preferred embodiments together with the accompanying
drawings in which:
[0009] FIG. 1 is a longitudinal sectional view of a compressor
according to a first embodiment of the present invention;
[0010] FIG. 2 is a transverse sectional view taken along the line
II-II of FIG. 1;
[0011] FIG. 3 is a graph showing the temperatures in suction
chamber of a compressor in operation according to a third
embodiment of the invention;
[0012] FIG. 4 is a longitudinal sectional view of a compressor
according to a fourth embodiment of the invention in which a
discharge chamber is formed surrounding a suction chamber;
[0013] FIG. 5 is a transverse sectional view taken along the line
V-V of FIG. 4;
[0014] FIG. 6 is a graph showing the temperatures in suction
chamber of a compressor in operation according to the fourth
embodiment of the invention; and
[0015] FIG. 7 is a cross-sectional view of a partition wall of a
compressor according to a fifth embodiment of the invention, the
partition wall having a suction chamber wall and a discharge
chamber wall filled with a thermal insulator therebetween.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0016] The following will describe the compressor according to the
first embodiment of the present invention with reference to FIGS. 1
and 2. Referring to FIG. 1, the compressor is designated generally
by numeral 1 and includes a suction chamber 2 into which
refrigerant gas is introduced, compression chambers 3 in which the
refrigerant gas in the suction chamber 2 is introduced and
compressed, and a discharge chamber 4 into which the compressed
refrigerant gas is discharged from the compression chamber 3. As
shown in FIGS. 1 and 2, the suction chamber 2 and the discharge
chamber 4 are formed adjacent to each other.
[0017] As shown in FIGS. 1 and 2, the suction chamber 2 and the
discharge chamber 4 are separated by a partition wall 5 the
opposite faces of which are provided with a thermal insulator 6.
The thermal insulator 6 is formed by curing a thermal insulation
coating composition. The thermal insulator 6 includes hollow beads
and one or more binder resins selected from the group consisting of
epoxy resin, polyamide-imide resin, phenolic resin and polyimide
resin.
[0018] As shown in FIG. 1, a rear housing 11, a valve plate 12, a
cylinder block 13, and a front housing 14 are disposed in this
order in the compressor 1 and any two adjacent components are
joined sealingly. It is to be noted that, in the following
description, the front housing 14 side is referred to as the front
side and the rear housing 11 side as the rear side of the
compressor 1, respectively.
[0019] As shown in FIG. 1, the suction chamber 2 and the discharge
chamber 4 are defined by and between the rear housing 11 and the
valve plate 12, and the partition wall 5 separating the suction
chamber 2 from the discharge chamber 4 is disposed in the rear
housing 11. Specifically, the partition wall 5 is formed projecting
horizontally from a rear end wall 111 of the rear housing 11 toward
the front (see FIG. 1). As shown in FIG. 2, the partition wall 5 is
formed annularly around the center of the rear housing 11, as
viewed from the front side. As shown in FIG. 1, the rear housing 11
includes an outer peripheral wall 112. The outer peripheral wall
112 and the partition wall 5 of the rear housing 11 are sealingly
joined at the respective ends thereof to the valve plate 12. With
this configuration, two spaces separated by the partition wall 5
are formed between the rear housing 11 and the valve plate 12. In
the first embodiment, of the two spaces separated by the partition
wall 5, the radially inner space serves as the discharge chamber 4
and the radially outer space as the suction chamber 2, as shown in
FIG. 2. In other words, the suction chamber 2 is formed so as to
surround the discharge chamber 4.
[0020] Referring to FIGS. 1 and 2, the thermal insulator 6 which is
formed by curing a thermal insulation coating composition is
provided on both surfaces of the partition wall 5, namely the
surface facing the discharge chamber 4 and the surface facing the
suction chamber 2. In the first embodiment, the thermal insulation
coating composition has the following composition. The ratios of
the components shown below were used in the preparation of the
thermal insulation coating composition.
Composition of the Thermal Insulation Coating Composition
[0021] Hollow beads: sodium aluminosilicate glass 28 percent by
mass (average particle diameter 29 .mu.m, specific gravity 0.12
g/cm.sup.3) [0022] Binder resin: phenolic resin 50 percent by mass
[0023] TiO.sub.2: 22 percent by mass
[0024] The thermal insulation coating composition of the above
composition was applied to the above both surfaces of the partition
wall 5. Then the coating composition was heated until cured. The
thickness of the resulting film of the cured thermal insulator 6
was 600 .mu.m. In the first embodiment, the chemical compositions
are the same between the thermal insulation coating composition and
the thermal insulator 6.
[0025] The compressor 1 will be described further in detail with
reference to FIG. 1.
[0026] The compressor 1 further includes a drive shaft 15. The
drive shaft 15 extends through the cylinder block 13 and rotatably
supported by bearings 150 mounted in the front housing 14 and the
cylinder block 13. The drive shaft 15 receives at the front end
thereof a drive force transmitted from an engine (not shown)
through a pulley or the like (not shown either) to be driven to
rotate.
[0027] The interior space of the front housing 14 serves as a crank
chamber 7 of the compressor 1. A lug plate 71 and a swash plate 72
are mounted on the drive shaft 15 in the crank chamber 7. The lug
plate 71 is disposed in the front part of the crank chamber 7 and
fixed on the drive shaft 15 for rotation therewith. The lug plate
71 is rotatably supported by the bearing 150 which is mounted on a
front end wall 141 of the front housing 14 (see FIG. 1).
[0028] The swash plate 72 is disk-shaped and mounted on the drive
shaft 15 in an inclinable manner with respect to the axis of the
drive shaft 15. The swash plate 72 has at the center thereof a hole
721 through which the drive shaft 15 is passed. The swash plate 72
is coupled with the lug plate 71 via a link mechanism 711. The
swash plate 72 is rotatable in synchronization with the drive shaft
15 and the lug plate 71 via the link mechanism 711.
[0029] The swash plate 72 has on the opposite surfaces thereof at
positions adjacent to the outer peripheral edge thereof a plurality
of pairs of front and rear shoes 73. The pairs of shoes 73 are
mounted so as to slidably hold therebetween the swash plate 72 and
slidably fitted in the rear ends of cylindrical pistons 74 (see
FIG. 1). The pairs of shoes 73 are moved back and forth by the
rotation of the swash plate 72, and the pistons 74 are reciprocated
back and forth by the reciprocating motion of the pairs of shoes
73.
[0030] The cylinder block 13 has therein a plurality of compression
chambers 3, in each of which refrigerant gas introduced from the
suction chamber 2 is compressed by the pistons 74. The compression
chambers 3 are defined by the valve plate 12, the cylinder block 13
and the pistons 74, and disposed around the drive shaft 15.
Although not shown, the compression chambers 3 are substantially
cylindrical and extend in the cylinder block 13 in the longitudinal
direction. The pistons 74 reciprocate as described above and vary
the internal volume of the compression chambers 3, thereby
compressing the refrigerant introduced into the compression
chambers 3.
[0031] The valve plate 12 has therethrough suction ports 121
through which the suction chamber 2 is communicable with the
compression chambers 3 (see FIG. 1) and discharge ports 122 through
which the compression chamber 3 is communicable with the discharge
chamber 4 (see FIG. 1).
[0032] The compressor 1 uses polyalkylene glycol as the lubricant
for enhancing the lubrication of the sliding part of the pistons
74, the pairs of shoes 73 and the other parts.
[0033] The following will describe the operation of the compressor
1 configured as described above. The compressor 1 according to the
first embodiment is adapted for use in an air conditioning system
of an automobile. Compression of refrigerant gas is accomplished by
the suction, compression and discharge phases of the pistons 74 in
the respective compression chambers 3. Low-temperature refrigerant
gas supplied from outside of the compressor 1 is introduced into
the suction chamber 2 through an inlet port 113 formed in the outer
peripheral wall 112 of the rear housing 11 (see FIG. 1).
[0034] Refrigerant gas in the suction chamber 2 passes through the
suction port 121 and is drawn into the compression chamber 3 which
is in the suction phase. In the compression chamber 3 in the
suction phase, the piston 74 moves toward the front with the
suction port 121 opened and the discharge port 122 closed, so that
the volume in the compression chamber 3 increases and the
refrigerant gas in the suction chamber 2 is introduced to the
compression chamber 3 through the suction port 121.
[0035] Subsequently, the compression of the refrigerant gas in the
compression chamber 3 is performed by the piston 74 moving rearward
in the compression chamber 3 with the suction port 121 and the
discharge port 122 both closed so that the volume in the
compression chamber 3 is reduced and the refrigerant gas in the
compression chamber 3 is compressed.
[0036] In the compression phase, the temperature of the compressed
refrigerant gas reaches a predetermined temperature, and then
discharging is performed. During the discharging, the suction port
121 is closed and the discharge port 122 is open and the volume of
the compression chamber 3 is reduced with the movement of the
piston 74 toward its top dead center. The compressed
high-temperature refrigerant gas is discharged into the discharge
chamber 4 through the discharge port 122. The refrigerant gas
discharged into the discharge chamber 4 is supplied to the external
circuit of the compressor 1 through an outlet port 114 formed
through the rear end wall 111 of the rear housing 11 (see FIG.
1).
[0037] The following will describe advantageous effects of the
compressor 1 according to the first embodiment. In the compressor 1
having the thermal insulator 6 on the opposite surfaces of the
partition wall 5 separating the suction chamber 2 from the
discharge chamber 4, heat of the refrigerant gas discharged into
the discharge chamber 4 is prevented from being easily transferred
to the suction chamber 2 that is located adjacent to the discharge
chamber 4, with the result that the temperature rise of the
refrigerant gas in the suction chamber 2 is suppressed easily and
the compression efficiency is enhanced accordingly.
[0038] The thermal insulator 6 also includes the hollow beads. Each
hollow bead has a shell having therein a hollow space. The presence
of such spaces created easily within the thermal insulator 6 by
mixing the hollow beads in the thermal insulator 6 provides high
thermal insulation property to the thermal insulator 6 reliably. As
a result, the temperature rise of the refrigerant gas in the
suction chamber 2 is suppressed easily, and the compression
efficiency is improved further.
[0039] The phenolic resin is selected for the binder resin. The
phenolic resin is highly heat resistant and durable against
refrigerant gas and lubricant. Therefore, the thermal insulator 6
when applied to the compressor 1 is less susceptible to
deterioration.
[0040] The sodium aluminosilicate glass which is used for the
hollow beads enhances the strength and the heat resistance of the
hollow beads. As a result, the compressor 1 is more excellent both
in compression efficiency and reliability.
[0041] The compressor 1 uses as the lubricant the polyalkylene
glycol which is suitable for lubrication of the compressor 1 in
that it offers good lubricating properties, heat resistance, cold
fluidity, and flame retardancy. As a result, the compressor 1 is
excellent both in compression efficiency and reliability.
[0042] The thermal insulator 6 is provided on both surfaces of the
partition wall 5 facing the discharge chamber 4 and facing the
suction chamber 2, respectively. The thermal insulator 6 that is
provided on the surface of the partition wall 5 facing the
discharge chamber 4 prevents direct contact between the partition
wall 5 and the refrigerant gas discharged from the compression
chamber 3 into the discharge chamber 4, so that heat of the
compressed refrigerant gas is prevented from being transferred
easily through the partition wall 5.
[0043] The thermal insulator 6 that is provided on the surface of
the partition wall 5 facing the suction chamber 2 prevents easy
temperature rise of the refrigerant gas in the suction chamber 2 as
compared with the case in which the thermal insulator 6 is provided
on only one surface of the partition wall 5. As a result, the
compressor 1 is more excellent in compression efficiency.
[0044] The suction chamber 2 is formed radially outward of the
discharge chamber 4 in the rear housing 11. Therefore, the
temperature rise of the refrigerant gas in the suction chamber 2
created when the refrigerant gas stays in contact with the
partition wall 5 for a relatively long time is suppressed more
effectively. As a result, the compressor 1 is excellent in
compression efficiency.
[0045] According to the first embodiment, the thermal insulation
coating composition used for the compressor 1 contains TiO.sub.2
(Titanium dioxide) having a high infrared reflectance and hence
being capable of readily reflecting the infrared rays emitted from
high-temperature refrigerant gas which is discharged into the
discharge chamber 4. Therefore, by providing the thermal insulator
6 containing the TiO.sub.2, the heat transfer by radiation from the
refrigerant gas to the partition wall 5 and hence the temperature
rise of the refrigerant gas in the suction chamber 2 is suppressed
easily and effectively. As a result, the compressor 1 is excellent
in compression efficiency.
[0046] The above-described compressor 1 having excellent
compression efficiency and reliability can be made smaller in size
readily and has high reliability required for use in a vehicle.
Thus, the compressor 1 is highly applicable to a vehicle air
conditioning system.
[0047] The following will describe a second embodiment according to
the present invention. In the second embodiment, evaluations were
made on the thermal insulator 6 in the compressor 1 of the first
embodiment by changing the binder resin in the test operation of
the compressor 1. In the second embodiment, three different thermal
insulation coating compositions containing phenolic resin,
polyamide-imide resin and epoxy resin, respectively, were prepared.
The polyamide-imide resin and the epoxy resin were used as an
alternative to the phenolic resin used in the first embodiment. The
thermal insulators 6 formed by curing the thermal insulation
coating compositions were applied to the partition wall 5 of the
compressors 1 in the same manner as in the first embodiment. Thus
three different compressors 1 which use phenolic resin,
polyamide-imide resin and epoxy resin, respectively, were
prepared.
[0048] The three compressors 1 thus prepared were individually
connected in an air conditioning system of a vehicle and operated
at 2,500 rpm for 24 hours, using R134a as the refrigerant. As the
testing conditions for the compressors 1, a pressure of 0.2 MPaG
was used for the suction chamber 2 and a pressure of 2.5 MPaG was
used for the discharge chamber 4, respectively.
[0049] After the testing operation, the rear housings 11 were
removed from the respective compressors 1 and a visual check was
made on each of the compressors 1 for peel-off of the thermal
insulator 6. The results showed that there was no peel-off of the
thermal insulator 6 in any of the compressors 1. It can be
appreciated from the results that the use of phenolic resin,
polyimide-imide resin, or epoxy resin as the binder resin enhances
the reliability of the thermal insulator 6 and hence the
reliability of the compressor 1.
[0050] The polyimide resin has an imide linkage like the
polyamide-imide resin. The imide linkage is very strong and,
therefore, the polyimide resin is highly heat resistant and durable
against refrigerant gas and lubricant, like the polyamide-imide
resin. It is expected therefore that, when the polyimide resin is
used as the binder resin, the reliability of the thermal insulator
6 is enhanced and the compressor 1 increases its reliability.
[0051] The following will describe the third embodiment according
to the present invention. In the third embodiment, evaluations were
made on the compressors 1 of the first embodiment as to the
compression efficiency and the reliability. The thermal insulator 6
used in the third embodiment contains hollow beads with a breaking
strength of 8 MPa. Other conditions conform to the first
embodiment. The breaking strength of the hollow beads was
determined as follows.
Measurement of the Breaking Strength of the Hollow Beads
[0052] The hollow beads were placed on a planar plate. Then a
compression tool having at the tip thereof a flat end face was
moved downward at the speed of 2 .mu.m/sec. The downward movement
of the compression tool was continued even after the end face of
the compression tool contacted the hollow beads, while maintaining
the moving speed, and the load occurring when the hollow beads were
broken was measured. Using the values of the measured loads and the
shell thickness of the hollow beads, the stress applied to the
hollow beads at the time of breaking was calculated to determine
the breaking strength.
Evaluation
[0053] The compressor 1 configured as descried above was connected
in an air conditioning system of a vehicle and operated for 180
minutes using R134a as the refrigerant and temperatures were
measured at the inner wall of the suction chamber 2 during the
operation of the compressor 1 and also when the compressor 1
entered a steady state. After the operation, the rear housing 11
was removed from the compressor 1 and a visual check was made for
peel-off of the thermal insulator 6. The above evaluation was
performed for each of the three different rotational speeds shown
in Table 1. The results are shown in Table 1 and FIG. 3. As the
operating conditions for the compressor 1, a pressure of 0.2 MPaG
was used for the suction chamber 2 and a pressure of 1.5 MPaG was
used for the discharge chamber 4, respectively. It is to be noted
that, in the compressor including the test body 2 shown in Table 1
and FIG. 3, the thermal insulator 6 was not provided on the rear
housing 11. However, the compressor 1 including the test body 2 had
the same configuration as the compressor 1 including the test body
1 in other respects, and the test bodies 1 and 2 were evaluated
under the same conditions.
TABLE-US-00001 TABLE 1 Rotational Temperature in Thermal speed
suction chamber insulation (rpm) (.degree. C.) coating Test body 1
1,000 27.50 Not peeled off (with thermal 1,800 25.40 Not peeled off
insulation coating) 3,000 25.50 Not peeled off Test body 2 1,000
36.20 -- (no coating) 1,800 33.70 -- 3,000 35.10 --
[0054] As can be seen from Table 1 and FIG. 3, the temperatures in
the suction chamber 2 of the test body 1 provided with the thermal
insulator 6 were lower than those of the test body 2 at any of the
rotational speeds. It is therefore assumed that, heat is prevented
from being easily transferred from the discharge chamber 4 to the
suction chamber 2 in the test body 1 due to the effect of the
thermal insulator 6. Accordingly, the temperature of the
refrigerant gas in the suction chamber 2 can be maintained at a low
level, so that refrigerant gas with a higher density can be
introduced into the compression chamber 3 during the suction phase.
As a result, the compression efficiency of the compressor 1 is
enhanced further.
[0055] As can be seen from Table 1, no peel-off was observed on the
thermal insulator 6 of the test body 1 at any of the rotational
speeds. The thermal insulator 6 of the above composition has a high
reliability, thus contributing to reliability of the compressor
1.
[0056] The hollow beads have a breaking strength of 3 MPa or more
that is high enough for the hollow beads to resist breakage due to
an external force such as pressure exerted by the refrigerant gas
or pressure due to the heat-expanded binder resin. Therefore, the
hollow beads in the thermal insulator 6 can well maintain the
hollow shape during the operation of the compressor 1, so that the
thermal insulator 6 offers excellent thermal insulation property.
Furthermore, the strength of the hollow beads prevents generation
of fragments due to any breakage of the hollow beads, which gives
the thermal insulator 6 a high reliability. As a result, the
compressor 1 is excellent both in compression efficiency and
reliability.
[0057] The following will describe the fourth embodiment according
to the present invention. FIGS. 4 and 5 illustrate a compressor 1
according to the fourth embodiment in which a discharge chamber 4
is formed so as to surround a suction chamber 2 in the rear housing
11. As shown in FIG. 4, a thermal insulator 6 is provided on both
surfaces facing the discharge chamber 4 and facing the suction
chamber 2, respectively, and also on the inner rear end wall 111 of
the rear housing 11. The rest of the structure of the compressor 1
of the fourth embodiment is substantially identical to the
corresponding structure of the compressor 1 according to the first
embodiment. It is to be noted that same reference numerals are used
in FIGS. 4 and 5 for common elements or components in the fourth
and the first embodiments, unless otherwise specified.
[0058] The compressor 1 described above was connected in an air
conditioning system of a vehicle, and experiments were performed in
the same manner as the third embodiment for the temperature at the
inner wall of the suction chamber 2 and the reliability of the
thermal insulator 6. The results are shown in Table 2 and FIG. 6.
It is to be noted that, in the compressor 1 including the test body
12 shown in Table 2 and FIG. 6, the thermal insulator 6 was not
provided on the rear housing 11. However, the compressor 1
including the test body 12 had the same configuration as the
compressor 1 including the test body 11 in other respects, and the
test bodies 11 and 12 were subjected to the same conditions.
TABLE-US-00002 TABLE 2 Rotational Temperature in Thermal speed
suction chamber insulation (rpm) (.degree. C.) coating Test body 11
1,000 26.70 Not peeled off (with thermal 1,800 22.20 Not peeled off
insulation coating) 3,000 21.70 Not peeled off Test body 12 1,000
31.80 -- (no coating) 1,800 26.30 -- 3,000 23.90 --
[0059] As can be seen from Table 2 and FIG. 6, the compressor 1
having the discharge chamber 4 formed so as to surround the suction
chamber 2 provides the same effect of thermal insulator 6 as the
second embodiment. It is therefore assumed that the provision of
the thermal insulator 6 prevents heat from being transferred easily
form the discharge chamber 4 to the suction chamber 2.
[0060] The following will describe the fifth embodiment according
to the present invention with reference to FIG. 7. The fifth
embodiment differs from the first embodiment in that the partition
wall 5 is double-walled, including two walls. Specifically, the
partition wall 5 provided in the rear housing 11 is formed by a
suction chamber wall 51 disposed on the suction chamber 2 side and
a discharge chamber wall 52 disposed on the discharge chamber 4
side, as shown in FIG. 7. The suction chamber wall 51 and the
discharge chamber wall 52 are spaced apart from each other and
filled with a thermal insulator 6 therebetween. It is to be noted
that same reference numerals are used in FIG. 7 for the common
elements or components in the fifth and the first embodiments,
unless otherwise specified.
[0061] The thermal insulator 6 is thus provided within the
partition wall 5 and does not easily contact with the refrigerant
gas or the lubricant, and therefore less susceptible to
deterioration. As a result, the reliability of the thermal
insulator 6 is enhanced further and the compressor 1 is more
reliable.
[0062] Although, in the first to fourth embodiments, the thermal
insulator 6 is provided on both surfaces of the partition wall 5
facing the discharge chamber 4 and facing the suction chamber 2,
respectively, the compressor according to the present invention is
not limited to these embodiments. For example, the thermal
insulator 6 may be provided only on the surface of the partition
wall 5 facing suction chamber 2, or only on the surface of the
partition wall 5 facing the discharge chamber 4. In either case,
transfer of heat between the suction chamber 2 and the discharge
chamber 4 is suppressed and the effect of enhancing the compression
efficiency of the compressor 1 can be expected.
[0063] Furthermore, the thermal insulation coating composition may
contain a silane coupling agent in addition to the hollow beads and
the binder resin. In such a case, the surface of the hollow beads
is modified by the silane coupling agent and the affinity between
the hollow beads and the binder resin is enhanced, accordingly.
Therefore, the thermal insulator 6 which is formed of the thermal
insulation coating composition containing the silane coupling agent
becomes less susceptible to peeling off. As a result the compressor
1 improves its reliability.
[0064] The thermal insulation 6 may be prepared by previously
coating the hollow beads with the silane coupling agent and then
mixing the hollow beads with the thermal insulation coating
composition. Alternatively, the silane coupling agent may be
directly mixed with the thermal insulation coating composition. In
the latter case, the surfaces of the hollow beads and the partition
wall 5 are modified by the silane coupling agent, so that the
affinity between the binder resin and the partition wall 5 is
enhanced further and the thermal insulator 6 is harder to peel
off.
[0065] In the compressor described above, the thermal insulator
should preferably contain the hollow beads in the range of 10 to 90
percent by mass. With the content of the hollow beads falling
within the above range, the thermal insulator offers good thermal
insulation property and reliability, so that the compressor
operates with an increased compression efficiency and
reliability.
[0066] Specifically, when the content of the hollow beads is 10
percent by mass or more, the thermal insulation property of the
thermal insulator is enhanced and, therefore, the temperature rise
of the refrigerant gas in the suction chamber is suppressed. As a
result, the compression efficiency of the compressor is enhanced.
For further enhancement of the thermal insulation property of the
thermal insulator, the content of the hollow beads should
preferably be 10 percent by mass or more, and more preferably 25
percent by mass or more.
[0067] With 90 percent by mass or less of the hollow beads content,
the thermal insulator may have sufficiently high content of the
binder resin and, therefore, peel-off of a part of the hollow beads
or the thermal insulator is prevented effectively. As a result, the
reliability of the compressor is enhanced. For further enhancement
of the reliability of the thermal insulator, the content of the
hollow beads should preferably be 90 percent by mass or less and
more preferably 70 percent by mass or less.
[0068] The average particle diameter of the hollow beads should
preferably be 100 .mu.m or smaller and more preferably in the range
between 15 .mu.m and 60 .mu.m. The hollow beads may be packed more
tightly and distributed more evenly in the thermal insulator with a
decrease of the average particle diameter of the hollow beads. As a
result, the thermal insulation property of the thermal insulator
may be enhanced further. For increasing the amount of the hollow
beads packed in the thermal insulator, therefore, the average
particle diameter of the hollow beads should preferably be 100
.mu.m or smaller and more preferably 60 .mu.m or smaller.
[0069] Although not specified, the lower limit of the average
particle diameter of the hollow beads should preferably be 15 .mu.m
or larger. When the average particle diameter is 15 .mu.m or
larger, the hollow volume of the hollow beads is sufficiently
large, so that the thermal insulation property of the thermal
insulator is enhanced further.
[0070] The hollow beads should preferably have a breaking strength
of 3 MPa or more. The hollow beads with the breaking strength of 3
MPa or more are strong enough to resist breakage by an external
force such as pressure of the refrigerant gas or pressure due to
the heat-expanded binder resin. Thus, the hollow shape of the
hollow beads in the thermal insulator is well maintained during the
operation of the compressor and the thermal insulator is more
excellent in thermal insulation property. Furthermore, generation
of fragments of the hollow beads is suppressed, which gives the
thermal insulator higher reliability. As a result, the compressor
operates with a high compression efficiency and reliability.
[0071] Various materials are usable for the hollow beads. The
materials for the hollow beads include ceramics such as silica,
alumina, flyash and glass, and also a plastic having a high heat
resistance.
[0072] The hollow beads should preferably be formed of a sodium
aluminosilicate glass. With the use of the sodium aluminosilicate
glass, the strength and the heat resistance of the hollow beads are
increased.
[0073] As the lubricant for the compressor, polyalkylene glycol or
polyol ester may be used. Polyalkylene glycol and polyol ester are
excellent in lubricity, heat resistance, cold fluidity, and flame
retardancy, thus being suitable as a lubricant for a compressor.
Therefore, the compressor is more excellent both in compression
efficiency and reliability.
[0074] The thermal insulator should preferably be provided at least
on the surface of the partition wall facing the discharge chamber.
As described above, the provision of the thermal insulator on at
least one surface of the partition wall suppresses transfer of heat
from the discharge chamber to the suction chamber. Furthermore, the
provision of the thermal insulator on the surface of the partition
wall facing the discharge chamber prevents direct contact between
the partition wall and the refrigerant gas discharged from the
compression chamber into the discharge chamber. With this
configuration, heat of the refrigerant gas is prevented from being
transferred easily through the partition wall and the temperature
rise of the refrigerant gas in the suction chamber is suppressed
easily. As a result, the compressor is more excellent in
compression efficiency.
[0075] When the thermal insulator is provided on both surfaces of
the partition wall facing the discharge chamber and facing the
suction chamber, respectively, the effect that the temperature rise
of the refrigerant gas in the suction chamber is suppressed is
enhanced further.
[0076] The partition wall may be double-walled, including a suction
chamber wall disposed on the suction chamber side and a discharge
chamber wall disposed on the discharge chamber side. The suction
chamber wall and the discharge chamber wall may be spaced from each
other and filled with the thermal insulator therebetween. With this
configuration, direct contact does not hardly occur between the
thermal insulation and refrigerant gas or lubricant, so that the
thermal insulation is less susceptible to deterioration. As a
result, reliability of the thermal insulation is more enhanced and
the compressor is more reliable.
[0077] The suction chamber should preferably be formed so as to
surround the discharge chamber. With this configuration, the
temperature rise of the refrigerant gas in the suction chamber is
suppressed more effectively. As a result, the compressor is more
excellent in compression efficiency. Specifically, with such
arrangement of the suction chamber and the discharge chamber, the
refrigerant gas introduced into the suction chamber flows on the
outer peripheral side of the partition wall, so that the
refrigerant gas would be in contact with the partition wall for a
relatively long time. With the use of the thermal insulator,
however, the temperature rise in the partition wall and hence the
temperature rise of the refrigerant gas in the suction chamber is
suppressed.
[0078] The compressor should preferably be used in a vehicle air
conditioning system. Compressors for use in a vehicle such as an
automobile are required to be small in size and of high performance
for improvement of fuel consumption. Compressors for vehicles are
also required to be highly reliable because they are used in harsh
environmental conditions involving vibrations and the like. The
compressor according to the present invention provides the desired
compression efficiency and reliability that meet the above
requirements. The compressor can easily be downsized with a high
level of reliability required for use in a vehicle. Accordingly,
the compressor is suitable for use in a vehicle air conditioning
system.
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