U.S. patent application number 13/256034 was filed with the patent office on 2012-01-05 for air conditioner.
This patent application is currently assigned to DAIKIN INDUSTRIES, LTD.. Invention is credited to Toshihiro Kizawa, Junichi Nakanishi, Kenjirou Suzuki.
Application Number | 20120000224 13/256034 |
Document ID | / |
Family ID | 42739438 |
Filed Date | 2012-01-05 |
United States Patent
Application |
20120000224 |
Kind Code |
A1 |
Kizawa; Toshihiro ; et
al. |
January 5, 2012 |
AIR CONDITIONER
Abstract
An air conditioner executes a heating operation using at least a
high pressure refrigerant, and includes a refrigerant circuit
configured to execute a vapor compression refrigeration cycle. The
refrigerant circuit includes a convective heat exchanger, a radiant
heat exchanger, an open/close valve and a check valve. The
convective heat exchanger executes heat exchange between the high
pressure refrigerant flowing inside and an air flowing towards
outside. The radiant heat exchanger heats a predetermined member
using the high pressure refrigerant flowing inside to cause the
predetermined member to emit a radiant heat. The open/close valve
is disposed upstream of the radiant heat exchanger in order to
block a flow path of the high pressure refrigerant flowing towards
the radiant heat exchanger during the heating operation. The check
valve is disposed between the radiant heat exchanger and the
open/close valve.
Inventors: |
Kizawa; Toshihiro; (Shiga,
JP) ; Nakanishi; Junichi; (Shiga, JP) ;
Suzuki; Kenjirou; ( Shiga, JP) |
Assignee: |
DAIKIN INDUSTRIES, LTD.
Osaka-shi, Osaka
JP
|
Family ID: |
42739438 |
Appl. No.: |
13/256034 |
Filed: |
March 15, 2010 |
PCT Filed: |
March 15, 2010 |
PCT NO: |
PCT/JP2010/001812 |
371 Date: |
September 12, 2011 |
Current U.S.
Class: |
62/132 ;
62/238.6 |
Current CPC
Class: |
F24F 1/0007 20130101;
F25B 2600/2515 20130101; F25B 13/00 20130101; F25B 2313/0314
20130101; F25B 41/20 20210101; F25B 2500/08 20130101; F24F 5/0089
20130101; F25B 2313/02334 20130101; F25B 2313/02741 20130101 |
Class at
Publication: |
62/132 ;
62/238.6 |
International
Class: |
F25B 29/00 20060101
F25B029/00; F25B 49/02 20060101 F25B049/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 18, 2009 |
JP |
2009-0066768 |
Claims
1. An air conditioner configured to execute a heating operation
using at least a high pressure refrigerant, the air conditioner
comprising: a refrigerant circuit configured to execute a vapor
compression refrigeration cycle, the refrigerant circuit including:
a convective heat exchanger configured to execute heat exchange
between the high pressure refrigerant flowing through an inside
thereof and an air flowing towards an outside thereof; a radiant
heat exchanger configured to heat a predetermined member by using
the high pressure refrigerant flowing through the inside thereof to
cause the predetermined member to emit a radiant heat; an
open/close valve disposed upstream of the radiant heat exchanger in
order to block a flow path of the high pressure refrigerant flowing
towards the radiant heat exchanger during the heating operation;
and a check valve disposed between the radiant heat exchanger and
the open/close valve.
2. The air conditioner recited in claim 1, wherein the open/close
valve is an opening degree regulating valve arranged and configured
to block the flow path and to regulate an opening degree of the
flow path.
3. The air conditioner recited in claim 1, wherein the open/close
valve is arranged and configured to block the flow path when a
temperature of the predetermined member reaches an upper limit of a
permissive temperature.
4. The air conditioner recited in claim 2, wherein the open/close
valve is further arranged and configured to block the flow path
when a temperature of the predetermined member reaches an upper
limit of a permissive temperature.
Description
TECHNICAL FIELD
[0001] The present invention relates to an air conditioner
including a refrigerant circuit configured to execute a vapor
compression refrigeration cycle.
BACKGROUND ART
[0002] Patent Literature 1 (Japan Laid-open Patent Application
Publication No. JP-A-H07-055234) describes an exemplary air
conditioner configured to execute a heating operation using a high
pressure refrigerant. Specifically, the exemplary air conditioner
is configured to cause the high pressure refrigerant to flow into a
radiant heat exchanger. In the exemplary air conditioner described
in Patent Literature 1 (Japan Laid-open Patent Application
Publication No. JP-A-H07-055234), a valve is disposed on the
downstream of the radiant heat exchanger for regulating the amount
of the high pressure refrigerant flowing into the radiant heat
exchanger during a heating operation. The valve is configured to
close the flow path for preventing the high pressure refrigerant
from flowing into the radiant heat exchanger when the temperature
of the radiant heat exchanger is increased to the upper limit.
SUMMARY OF THE INVENTION
Technical Problem
[0003] In the aforementioned structure, however, the high pressure
refrigerant is trapped in the radiant heat exchanger by means of
the pressure of a compressor. Accordingly, the refrigerant, a
compressor oil and etc. reside in the radiant heat exchanger. This
makes it difficult to lower the temperature of the refrigerant. In
other words, the temperature of the radiant heat exchanger cannot
be lowered when necessary. Further, the amount of the compressor
oil to be returned to the compressor is reduced. Therefore, chances
will be increased that reliability of the compressor is
deteriorated.
[0004] In view of the above, the applicant of the present invention
produced a structure for preventing the high pressure refrigerant
from being trapped in the radiant heat exchanger. Specifically in
the structure, an open/close valve is disposed on the upstream of
the radiant heat exchanger for blocking the flow path of the high
pressure refrigerant flowing towards the radiant heat exchanger.
Even in the structure, the refrigerant is changed into liquid in
the radiant heat exchanger during a heating operation and resides
in the vicinity of the radiant heat exchanger and the open/close
valve. When the liquid refrigerant spontaneously evaporates under
the condition and the internal pressure is increased, the
open/close valve is pushed and repeatedly opened and closed by
means of the increased internal pressure. This phenomenon is
so-called "chattering".
[0005] It is an object of the present invention to provide an air
conditioner preventing occurrence of chattering in an open/close
valve even when a refrigerant is changed into liquid in a radiant
heat exchanger and resides in the vicinity of the radiant heat
exchanger and the open/close valve during a heating operation.
Solution to Problem
[0006] An air conditioner according to a first aspect of the
present invention includes a refrigerant circuit configured to
execute a vapor compression refrigeration cycle and is configured
to execute a heating operation using at least a high pressure
refrigerant. In the air conditioner, the refrigerant circuit
includes a convective heat exchanger, a radiant heat exchanger, an
open/close valve and a check valve. The convective heat exchanger
is configured to execute heat exchange between the high pressure
refrigerant flowing through the inside thereof and an air flowing
towards the outside thereof. The radiant heat exchanger is
configured to heat a predetermined member by means of the high
pressure refrigerant flowing through the inside thereof for causing
the predetermined member to emit a radiant heat. The open/close
valve is disposed on the upstream of the radiant heat exchanger for
blocking a flow path of the high pressure refrigerant flowing
towards the radiant heat exchanger during the heating operation.
The check valve is disposed between the radiant heat exchanger and
the open/close valve.
[0007] According to the air conditioner of the first aspect of the
present invention, the check valve is disposed between the radiant
heat exchanger and the open/close valve. When the open/close valve
is closed, less liquid refrigerant exists between the open/close
valve and the check valve. Even when the liquid refrigerant
spontaneously evaporates and the internal pressure is increased,
the internal pressure is not increased enough to push and open the
open/close valve. Occurrence of chattering is thereby
prevented.
[0008] An air conditioner according to a second aspect of the
present invention relates to the air conditioner according to the
first aspect of the present invention. In the air conditioner, the
open/close valve is an opening degree regulating valve having a
function of blocking the flow path and a function of regulating an
opening degree of the flow path.
[0009] According to the air conditioner of the second aspect of the
present invention, performance of the radiant heat exchanger is
increased or reduced by regulating the opening degree of the
refrigerant flow path. Further, the refrigerant flow path is
configured to be blocked when the performance of the radiant heat
exchanger reaches a predetermined set value. Convenience and
security of the air conditioner can be thereby enhanced.
[0010] An air conditioner according to a third aspect of the
present invention relates to the air conditioner according to one
of the first and second aspects of the present invention. In the
air conditioner, the open/close valve is configured to block the
flow path when a temperature of the predetermined member reaches an
upper limit of a permissive temperature.
[0011] According to the air conditioner of the third aspect of the
present invention, the high pressure refrigerant is prevented from
flowing into the radiant heat exchanger when the temperature of the
predetermined member of the radiant heat exchanger reaches the
upper limit of the permissive temperature thereof during execution
of a heating operation using the radiant heat exchanger. Therefore,
reduction in the temperature of the refrigerant is accelerated
within the radiant heat exchanger. As a result, reduction in the
temperature of the predetermined member is accelerated and the air
conditioner can be returned to the heating operation using the
radiant heat exchanger.
Advantageous Effects of Invention
[0012] According to the air conditioner of the first aspect of the
present invention, less liquid refrigerant exists between the
open/close valve and the check valve. Even when the liquid
refrigerant spontaneously evaporates and the internal pressure is
increased, the internal pressure is not increased enough to push
and open the open/close valve. Occurrence of chattering is thereby
prevented.
[0013] According to the air conditioner of the second aspect of the
present invention, performance of the radiant heat exchanger is
increased or reduced by regulating the opening degree of the
refrigerant flow path. Further, the refrigerant flow path is
configured to be blocked when the performance of the radiant heat
exchanger reaches a predetermined set value. Convenience and
security of the air conditioner can be thereby enhanced.
[0014] According to the air conditioner of the third aspect of the
present invention, the high pressure refrigerant is prevented from
flowing into the radiant heat exchanger when the temperature of the
predetermined member of the radiant heat exchanger reaches the
upper limit of the permissive temperature thereof during execution
of a heating operation using the radiant heat exchanger. Therefore,
reduction in the temperature of the refrigerant is accelerated
within the radiant heat exchanger. As a result, reduction in the
temperature of the predetermined member is accelerated and the air
conditioner can be returned to the heating operation using the
radiant heat exchanger.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a refrigerant circuit diagram of an air
conditioner according to an exemplary embodiment of the present
invention.
[0016] FIG. 2 is an exploded perspective view of the internal
structure of an indoor unit.
[0017] FIG. 3 is a side view of a heat exchanger assembly.
[0018] FIG. 4 is a cross-sectional view of a radiant heat
exchanger, illustrating an exemplary attachment structure of a
panel and heat transfer tubes.
[0019] FIG. 5 is a chart representing the relation between
temperature to be detected by a second temperature sensor and
actions of an open/close valve during a heating operation.
[0020] FIG. 6 is a cross-sectional view of the radiant heat
exchanger, illustrating a second attachment structure of the panel
and the heat transfer tubes.
[0021] FIG. 7 is a cross-sectional view of the radiant heat
exchanger, illustrating a third attachment structure of the panel
and the heat transfer tubes.
[0022] FIG. 8 is a cross-sectional view of the radiant heat
exchanger, illustrating a fourth attachment structure of the panel
and the heat transfer tubes.
[0023] FIG. 9 is a cross-sectional view of the radiant heat
exchanger, illustrating a fifth attachment structure of the panel
and the heat transfer tubes.
[0024] FIG. 10 is a cross-sectional view of the radiant heat
exchanger, illustrating a sixth attachment structure of the panel
and the heat transfer tubes.
DESCRIPTION OF EMBODIMENTS
[0025] An exemplary embodiment of the present invention will be
hereinafter explained with reference to figures. It should be noted
that the following exemplary embodiment is merely a specific
example of the present invention, and therefore does not intend to
limit the technical scope of the present invention.
[0026] <Refrigerant Circuit 10 for Air Conditioner 1>
[0027] FIG. 1 is a refrigerant circuit diagram of an air
conditioner according to the exemplary embodiment of the present
invention. As illustrated in FIG. 1, the air conditioner 1 includes
an indoor unit 2 mainly disposed in the indoor space and an outdoor
unit 3 mainly disposed in the outdoor space. The indoor unit 2 and
the outdoor unit 3 are connected through a refrigerant
communication piping, and the structure forms a refrigerant circuit
10 configured to execute a vapor compression refrigeration
cycle.
[0028] In the refrigerant circuit 10, a compressor 11, a four-way
switching valve 12, a convective heat exchanger 13, an expansion
valve 15, an outdoor heat exchanger 16 are sequentially connected.
Further, a branch pipe 40 is disposed in parallel to the convective
heat exchanger 13. An open/close valve 41, a first check valve 42,
a radiant heat exchanger 14 and a second check valve 43 are
series-connected to the branch pipe 40 while being sequentially
aligned from the compressor 11 side. Further, an accumulator 20 is
connected to the four-way switching valve 12 and the inlet of the
compressor 11.
[0029] The four-way switching valve 12 is configured to cause the
refrigerant discharged from the compressor 11 to flow towards
either the convective heat exchanger 13 or the outdoor heat
exchanger 16. During a heating operation, for instance, a control
unit is configured to cause the four-way switching valve 12 to
select a flow path depicted with a solid line in FIG. 1 for causing
the refrigerant to flow towards the convective heat exchanger 13.
During a cooling operation, by contrast, the control unit is
configured to cause the four-way switching valve 12 to select a
flow path depicted with a dotted line in FIG. 1 for causing the
refrigerant to flow towards the outdoor heat exchanger 16.
[0030] The convective heat exchanger 13 is a type of heat exchanger
formed by a plurality of fins and a plurality of heat transfer
tubes arranged perpendicularly to the fins. The convective heat
exchanger 13 is configured to execute heat exchange between the
refrigerant flowing through the heat transfer tubes and the air
flowing against the surfaces of the fins. A fan 23 is disposed in
the vicinity of the convective heat exchanger 13 for supplying air
towards the surfaces of the fins.
[0031] The radiant heat exchanger 14 is a type of heat exchanger
formed by a plate (hereinafter referred to as a panel) made of
aluminum and heat transfer tubes attached to the panel. The radiant
heat exchanger 14 is configured to heat the panel by means of the
high pressure refrigerant flowing through the heat transfer tubes
for causing the panel to emit radiant heat.
[0032] The expansion valve 15 is an electronic expansion valve
functioning as a decompression mechanism. The expansion valve 15 is
connected between the convective heat exchanger 13 and the outdoor
heat exchanger 16. The expansion valve 15 is configured to narrow
the refrigerant flow path for decompressing the refrigerant. The
outdoor heat exchanger 16 is a type of heat exchanger formed by a
plurality of fins and a plurality of heat transfer tubes arranged
perpendicularly to the fins. The outdoor heat exchanger 16 is
configured to execute heat exchange between the refrigerant flowing
through the heat transfer tubes and the air flowing against the
surfaces of the fins. Further, an outdoor fan 33 is disposed in the
vicinity of the outdoor heat exchanger 16 for supplying air towards
the surfaces of the fins. The accumulator 20 is configured to
accumulate excessive liquid refrigerant and return only gas
refrigerant to the compressor 11.
[0033] A discharge temperature sensor 111 is attached to a
discharge pipe connecting the outlet of the compressor 11 and the
four-way switching valve 12. The discharge temperature sensor 111
is configured to detect the temperature of the high pressure
refrigerant to be discharged from the compressor 11.
[0034] The control unit is configured to control the temperature of
the panel of the radiant heat exchanger 14 based on the temperature
to be detected by the discharge temperature sensor 111. However,
another temperature sensor (hereinafter referred to as a second
temperature sensor 114) may be attached in the vicinity of the high
pressure refrigerant inlet of the radiant heat exchanger 14 when
the temperature to be detected by the discharge temperature sensor
111 and the temperature of the panel are different due to pressure
loss caused by a long pipe connecting the open/close valve 41 and
the radiant heat exchanger 14. It should be noted that both of the
discharge temperature sensor 111 and the second temperature sensor
114 are used in the present exemplary embodiment.
[0035] <Internal Structure of Indoor Unit 2>
[0036] FIG. 2 is an exploded perspective view of the internal
structure of the indoor unit. In FIG. 2, the outer shell of the
indoor unit 2 is formed by a frame 210 and a grill 240. In the
frame 210, a left plate 212, a right plate 213 and a top plate 214
are respectively fixed to the left end, the right end and the top
end of a rectangular opening 211. The frame 210 includes a fan
compartment 210a and an electric component compartment 210b.
[0037] The grill 240 includes an upper blower vent 240a, a lower
blower vent 240b, an opening 240c, a left suction vent 240d and a
right suction vent 240e. The upper blower vent 240a is positioned
on the upper part of the grill 240, whereas the lower blower vent
240b is positioned on the lower part of the grill 240. The opening
240c is formed for exposing a panel 14a to the indoor space. The
left suction vent 240d is positioned on the left face of the grill
240, whereas the right suction vent 240e is positioned on the right
face of the grill 240.
[0038] Air is inhaled through the left suction vent 240d and the
right suction vent 240e in conjunction with activation of the fan
23 and passes through a filter 218 disposed on the upstream of the
convective heat exchanger 13 via spaces between the heat insulated
rear face of the panel 14a and suction path forming plates 115 and
116. After passing through the filter 218, the air is directed to
the convective heat exchanger 13. Heat exchange is then executed
for the air in the convective heat exchanger 13. The heat-exchanged
air passes through a circular hole 216a of a bell mouth 216 and
enters the fan 23. The air is then blown out of the fan 23, travels
through the fan compartment 210a towards the upper blower vent 240a
and the lower blower vent 240b, and is blown out through the upper
blower vent 240a and the lower blower vent 240b.
[0039] The circular hole 216a of the bell mouth 216 has a diameter
slightly less than the vane inner diameter of the fan 23. When
passing through the circular hole 216a, the air enters between the
vanes of the fan 23 and is compressed by the vanes of the fan 23.
The compressed air is blown out in the outer peripheral direction
of the fan 23.
[0040] A motor support plate 215 is disposed and fixed between the
top and the bottom of the fan compartment 210a for supporting a
driving motor 23a of the fan 23. The driving motor 23a is fixed to
the motor support plate 215 by means of screws 23b. The bell mouth
216 then closes the fan compartment 210a. An electric component box
24 is held in the electric component compartment 210b. The electric
component box 24 accommodates the control unit embedded with a CPU,
a memory and etc.
[0041] A heat exchanger assembly 220 is an integrated structure of
the convective heat exchanger 13 and the radiant heat exchanger 14.
A drain pan assembly 217 is disposed below the convective heat
exchanger 13. During a cooling operation, for instance, moisture
contained in the air is condensed on the surface of the convective
heat exchanger 13 when the air passes through the conductive heat
exchanger 13. The drain pan assembly 217 receives such condensed
water falling from the convective heat exchanger 13.
[0042] It should be noted that a blower vent assembly 250 is
attached to the upper blower vent 240a. The blower vent assembly
250 includes a louver for changing an air blowing-out direction.
Further, a left frame bar 241, a right frame bar 242 and an upper
frame bar 243 are respectively attached to the left edge, the right
edge, and the upper edge of the opening 240c of the grill 240.
[0043] FIG. 3 is a side view of the heat exchanger assembly. In the
heat exchanger assembly 220 of FIG. 3, the convective heat
exchanger 13 and the radiant heat exchanger 14 are fixed to each
other by means of attachment plates 221. Each attachment plate 221
is a sheet-metal member extended from a frame 14c of the radiant
heat exchanger 14 in an opposite direction to the panel 14a. Each
attachment plate 221 includes through holes 221a.
[0044] The convective heat exchanger 13 includes a pair of tube
plates 13c in the vicinity of the both ends of each heat transfer
tube 13b. Each tube plate 13c includes screw holes to be matched
with the through holes 221a of the attachment plates 221. The
convective heat exchanger 13 and the attachment plates 221 are
fixed by means of screws via the through holes 221a.
[0045] FIG. 4 is a cross-sectional view of the radiant heat
exchanger for illustrating an exemplary attachment structure of the
panel and the heat transfer tubes. In FIG. 4, attachment brackets
14e are opposed to the panel 14a while heat transfer tubes 14b are
interposed therebetween. Specifically, the attachment brackets 14e
are fixed to bracket receivers 14d having preliminarily fixed to
the panel 14a by means of attachment screws 14f. Each bracket
receiver 14d includes a screw hole 14da that one of the attachment
screws 14f is screwed. Each attachment bracket 14e includes a flat
plate portion 14ea, a bulged portion 14eb and flanged portions
14ec. The flat plate portion 14ea is closely attached to the rear
face, opposite to the radiant face, of the panel 14a. The bulged
portion 14eb is bulged from the flat plate portion 14ea for forming
a U-shaped groove that one of the heat transfer tubes 14b is
fitted. The flanged portions 14ec, bulged from the both ends of the
flat plate portion 14ea, are fixed to the bracket receivers 14d.
Each flanged portion 14ec includes a through hole 14ed to be
matched with the screw hole 14da of each bracket receiver 14d.
[0046] The heat transfer tubes 14b are firstly disposed on the rear
face of the panel 14a. Subsequently, the attachment brackets 14e
are respectively disposed while the through holes 14ed thereof are
faced to the screw holes 14da of the bracket receivers 14d. Under
the condition, the flanged portions 14ec of the attachment brackets
14e are respectively fixed to the bracket receivers 14d by means of
the attachment screws 14f. Consequently, the attachment brackets
14e and the heat transfer tubes 14b are pressed onto the panel 14a.
Heat can be thereby reliably transferred from the attachment
brackets 14e and the heat transfer tubes 14b to the panel 14a.
[0047] <Actions of Air Conditioner 1>
[0048] The air conditioner 1 is configured to cause the four-way
switching valve 12 to change the refrigerant flow path for
switching between a cooling operation and a heating operation.
First, an exemplary case will be explained that the refrigerant
circuit functions as a circuit for a heating operation.
[0049] (Heating Operation)
[0050] During a heating operation, the flow path depicted with the
solid line in FIG. 1 is selected in the four-way switching valve
12. Accordingly, the high pressure gas refrigerant, discharged from
the compressor 11, branches into and flows through the branch pipe
40 and the convective heat exchanger 13. The branch point of the
refrigerant flow is hereinafter referred to as a point A. The gas
refrigerant, flowing into the branch pipe 40 at the point A,
sequentially flows through the open/close valve 41, the first check
valve 42, the radiant heat exchanger 14 and the second check valve
43, and then joins the refrigerant flowing from the convective heat
exchanger 13. The confluence of the refrigerant flows is
hereinafter referred to as a point B.
[0051] The attachment brackets 14e and the heat transfer tubes 14b
are closely attached to the panel 14a (see FIG. 4). The heat of the
gas refrigerant is thereby transferred to the panel 14a through the
heat transfer tubes 14b. Accordingly, the panel 14a increases its
temperature. The panel 14a with increased temperature herein emits
radiant heat. Therefore, air and objects, positioned ahead the
panel 14a, are heated by the radiant heat. In the radiant heat
exchanger 14, the gas refrigerant is partially condensed by means
of heat exchange with the panel 14a. Therefore, the liquid
refrigerant and the gas refrigerant herein coexist in the radiant
heat exchanger 14.
[0052] The gas refrigerant, flowing into the convective heat
exchanger 13 at the point A, is condensed as a result of heat
exchange with the air flowing against the outside of the convective
heat exchanger 13. On the other hand, the air increases its
temperature in the convective heat exchanger 13 and is blown out to
the indoor space for heating the indoor space.
[0053] Further, the liquid refrigerant, flowing out of the
convective heat exchanger 13, joins the refrigerant flowing out of
the radiant heat exchanger 14 at the point B. The joined
refrigerant subsequently flows towards the outdoor heat exchanger
16. On the way to the outdoor heat exchanger 16, the joined
refrigerant is decompressed in the expansion valve 15. The
decompressed refrigerant then flows into the outdoor heat exchanger
16. In the outdoor heat exchanger 16, the refrigerant evaporates
and changes into the gas refrigerant as a result of heat exchange
with the air flowing against the outside of the outdoor heat
exchanger 16.
[0054] After flowing out of the outdoor heat exchanger 16, the gas
refrigerant is returned to the compressor 11 via the four-way
switching valve 12 and the accumulator 20. The air conditioner 1 is
thus configured to execute a heating operation using the radiant
heat exchanger 14 and the convective heat exchanger 13.
[0055] FIG. 5 is a chart representing the relation between
temperature to be detected by the second temperature sensor and
actions of the open/close valve during a heating operation. In FIG.
5, the open/close valve 41 is configured to switch the flow path
from an opened state to a closed state when the temperature
detected by the second temperature sensor 114 exceeds a
predetermined temperature (herein set as 70 degrees Celsius). In
other words, the open/close valve 41 is configured to switch a
state of the refrigerant flowing into the radiant heat exchanger 14
to a state of the refrigerant flowing into only the convective heat
exchanger 13 without flowing into the radiant heat exchanger
14.
[0056] When a preliminarily set switching period of time T1
elapses, the open/close valve 41 is configured to switch the flow
path back to the opened state from the closed state. Accordingly,
the air conditioner 1 is returned to the heating operation using
the radiant heat exchanger 14.
[0057] During a heating operation only using the convective heat
exchanger 13, the liquid refrigerant and the gas refrigerant remain
residing between the open/close valve 41 and the point B. When the
liquid refrigerant spontaneously evaporates under the condition,
the internal pressure is increased between the open/close valve 41
and the point B. In the present exemplary embodiment, however, the
first check valve 42 is disposed between the radiant heat exchanger
14 and the open/close valve 41. Even when the liquid refrigerant
spontaneously evaporates and the internal pressure is increased,
the pressure within the radiant heat exchanger 14 does not affect
the open/close valve 41. Further, less liquid refrigerant exists
between the open/close valve 41 and the first check valve 42. Even
when the liquid refrigerant existing therein spontaneously
evaporates and the internal pressure is increased, the internal
pressure is not increased enough to push and open the open/close
valve 41. Therefore, occurrence of chattering is herein
prevented.
[0058] When the panel 14a of the radiant heat exchanger 14
sufficiently reduces its temperature during a heating operation
only using the convective heat exchanger 13, the branch pipe 40 is
opened by the open/close valve 41 and the heating operation is
again executed by the radiant heat exchanger 14 and the convective
heat exchanger 13.
[0059] (Cooling Operation)
[0060] Next, an exemplary case will be explained that the
refrigerant circuit functions as a circuit for a cooling operation.
During a cooling operation, the flow path depicted with the dotted
line in FIG. 1 is selected in the four-way switching valve 12.
Accordingly, the high pressure gas refrigerant, discharged from the
compressor 11, flows towards the outdoor heat exchanger 16. The gas
refrigerant is condensed as a result of heat exchange with the air
flowing against the outside of the outdoor heat exchanger 16. The
liquid refrigerant, flowing out of the outdoor heat exchanger 16,
flows towards the convective heat exchanger 13. On the way to the
convective heat exchanger 13, the liquid refrigerant is
decompressed in the expansion valve 15. The decompressed
refrigerant then flows into the convective heat exchanger 13. It
should be noted that the liquid and gas refrigerant is blocked from
flowing into the branch pipe 40 at the point B by the second check
valve 43 before flowing into the convective heat exchanger 13.
[0061] In the convective heat exchanger 13, the liquid refrigerant
evaporates and changes into the gas refrigerant as a result of heat
exchange with the air flowing against the outside of the convective
heat exchanger 13. On the other hand, the air reduces its
temperature in the convective heat exchanger 13 and is blown out to
the indoor space for cooling the indoor space. The gas refrigerant
flows out of the convective heat exchanger 13 and flows towards the
four-way switching valve 12 via the point A. The gas refrigerant is
then returned to the compressor 11 via the four-way switching valve
12 and the accumulator 20.
[0062] <Features>
[0063] According to the air conditioner 1, as described above, the
branch pipe 40 is configured to be closed by the open/close valve
41 for blocking the high pressure refrigerant from flowing into the
radiant heat exchanger 14 when the temperature of the panel 14a of
the radiant heat exchanger 14 reaches the upper limit of its
permissive temperature during a heating operation using the radiant
heat exchanger 14. As a result, reduction in the temperature of the
refrigerant is accelerated within the radiant heat exchanger 14 and
reduction in the temperature of the panel 14a is also accelerated.
Therefore, the air conditioner 1 can be returned to the heating
operation using the radiant heat exchanger 14.
[0064] Further, the first check valve 42 is disposed between the
radiant heat exchanger 14 and the open/close valve 41. Therefore,
less liquid refrigerant exists between the open/close valve 41 and
the first check valve 42 when the open/close valve 41 is closed.
Even when the liquid refrigerant spontaneously evaporates and the
internal pressure is increased, the internal pressure is not
increased enough to push and open the open/close valve 41.
Therefore, occurrence of chattering is prevented.
[0065] <Modification>
[0066] In the aforementioned exemplary embodiment, the open/close
valve 41 is employed for closing and opening the branch pipe 40.
However, an opening degree regulating valve may be used instead of
the open/close valve 41. The opening degree regulating valve herein
has a function of blocking the flow path of the branch pipe 40 and
a function of regulating the opening degree of the flow path of the
branch pipe 40.
[0067] With the opening degree regulating valve, the temperature of
the panel 14a of the radiant heat exchanger 14 is increased or
reduced by regulating the opening degree of the flow path. Further,
the flow path of the refrigerant is configured to be blocked when
the temperature of the panel 14a reaches its upper limit.
Therefore, the opening degree regulating valve can enhance
convenience and safety of the air conditioner 1.
[0068] <Other Modifications>
[0069] The attachment structure of the panel 14a and the heat
transfer tubes 14b in the radiant heat exchanger 14 is not limited
to that illustrated in FIG. 4. Other attachment structures will be
hereinafter explained with reference to FIGS. 6 to 10. It should be
noted that the face, opposite to the radiant face, of the panel 14a
will be hereinafter referred to as a rear face for the sake of easy
explanation.
[0070] FIG. 6 is a cross-sectional view of the radiant heat
exchanger for illustrating a second attachment structure of the
panel and the heat transfer tubes. In FIG. 6, each of attachment
panels 141 includes a flat plate portion 141a and bulged portions
141b. The flat plate portion 141a is joined to the rear face of the
panel 14a, whereas the bulged portions 141b are bulged from the
flat plate portion 141a. Each bulged portion 141b is bulged higher
than the diameter of each heat transfer tube 14b. Each bulged
portion 141b includes a U-shaped groove 141c that one of the heat
transfer tubes 14b is fitted. Each heat transfer tube 14b is fitted
into corresponding one of the U-shaped grooves 141c and then the
edges of the opening of the U-shaped groove 141c are pressed and
swaged onto the outer peripheral surface of each heat transfer tube
14b.
[0071] FIG. 7 is a cross-sectional view of the radiant heat
exchanger for illustrating a third attachment structure of the
panel and the heat transfer tubes. In FIG. 7, the panel 14a and the
heat transfer tubes 14b are jointed by means of brazing. In this
case, a filler material 140 is filled with corners (i.e.,
clearances) produced in contact portions between the panel 14a and
the heat transfer tubes 14b. Therefore, heat can be efficiently
transferred from the heat transfer tubes 14b to the panel 14a.
[0072] FIG. 8 is a cross-sectional view of the radiant heat
exchanger for illustrating a fourth attachment structure of the
panel and the heat transfer tubes. In FIG. 8, each of first
attachment brackets 341 includes a flat plate portion 341a and a
bulged portion 341b. The flat plate portion 341a is joined to the
rear face of the panel 14a, whereas the bulged portion 341b is
bulged from the flat plate portion 341a. The flat plate portion
341a is closely joined to the rear face of the panel 14a by means
of either spot welding or brazing. The bulged portion 341b is
bulged at a height roughly the same as the diameter of each heat
transfer tube 14b. The bulged portion 341b includes a U-shaped
groove 341c that one of the heat transfer tubes 14b is fitted.
Further, the bulged portion 341b includes screw holes 341d on the
both sides of the U-shaped groove 341c.
[0073] Each of second attachment brackets 342 includes through
holes 342a to be matched with the screw holes 341d of corresponding
one of the first attachment brackets 341. The second attachment
brackets 342 are respectively fixed to the first attachment
brackets 341 by means of screws 343 for covering the heat transfer
tubes 14b respectively fitted into the U-shaped grooves 341c. The
respective heat transfer tubes 14b are herein slightly protruded
from the U-shaped grooves 341c. Therefore, the heat transfer tubes
14b are respectively pressed and closely fitted to the U-shaped
grooves 341c when the second attachment brackets 342 are
respectively fixed to the first attachment brackets 341 by means of
screws.
[0074] FIG. 9 is a cross-sectional view of the radiant heat
exchanger for illustrating a fifth attachment structure of the
panel and the heat transfer tubes. In FIG. 9, each of presser
brackets 441 includes a flat plate portion 441a and a U-shaped
groove 441b. The flat plate portion 441a is joined to the rear face
of the panel 14a. The U-shaped groove 441b is opposed to the rear
face of the panel 14a while one of the heat transfer tubes 14b is
interposed therebetween. Specifically, the heat transfer tubes 14b
are disposed on the rear face of the panel 14a and are then
respectively covered with the U-shaped grooves 441b of the presser
brackets 441. Under the condition, the flat plate portions 441a of
the presser brackets 441 and the rear face of the panel 14a are
joined by means of either spot welding or brazing.
[0075] FIG. 10 is a cross-sectional view of the radiant heat
exchanger for illustrating a sixth attachment structure of the
panel and the heat transfer tubes. In FIG. 10, the panel 14a
includes bulged portions 541 on the rear face thereof. The bulged
portions 541 are arranged in the positions where the heat transfer
tubes 14b are disposed. Each bulged portion 541 includes a U-shaped
groove 541a that one of the heat transfer tubes 14b is fitted. The
U-shaped groove 541a has a predetermined depth for allowing the
outer peripheral surface of each heat transfer tube 14b to be
slightly protruded therefrom when fitted therein. Further, each
bulged portion 541 includes screw holes 541b on the both sides of
the U-shaped groove 541a.
[0076] Each of presser brackets 542 includes through holes 542a to
be matched with the screw holes 541b of corresponding one of the
bulged portions 541. The presser brackets 542 are respectively
fixed to the bulged portions 541 by means of screws 543 for
covering the outer peripheral surfaces of the heat transfer tubes
14b respectively slightly protruded from the bulged portions
541.
INDUSTRIAL APPLICABILITY
[0077] As described above, the present invention is useful for a
heating machine using a radiant heat exchanger.
REFERENCE SIGNS LIST
[0078] 1 Air conditioner [0079] 10 Refrigerant circuit [0080] 13
Convective heat exchanger [0081] 14 Radiant heat exchanger [0082]
41 Open/close valve [0083] 42 First check valve
CITATION LIST
Patent Literature
[0083] [0084] PTL 1: Japan Laid-open Patent Application Publication
No. JP-A-H07-055234
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