Information
-
Patent Grant
-
6233969
-
Patent Number
6,233,969
-
Date Filed
Wednesday, December 8, 199924 years ago
-
Date Issued
Tuesday, May 22, 200123 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Harness, Dickey & Pierce, PLC
-
CPC
-
US Classifications
Field of Search
US
- 062 513
- 062 113
- 062 511
- 062 204
- 062 205
- 062 206
- 062 210
- 062 211
- 062 212
- 062 222
- 062 223
- 062 224
- 062 225
-
International Classifications
-
Abstract
In a decompression device-integrated heat exchanger, a pressure-reducing unit for reducing high-pressure refrigerant of a refrigerant cycle, and an inner heat-exchanging unit for performing heat-exchange between high-pressure refrigerant before being decompressed in the pressure-reducing unit and low-pressure refrigerant after being decompressed in the pressure reducing unit are integrated to each other. The inner heat-exchanging unit has a high-pressure tube through which high-pressure refrigerant flows, and a low-pressure tube through which low-pressure refrigerant flows. Both the tubes are wound around a case of the pressure-reducing unit, and are brazed to the case on contacting portions therebetween. Further, in each tube, wall thickness of the contacting portion is made thinner than that of the other portion. Thus, the decompression device-integrated heat exchanger has a reduced weight, while having a simple structure.
Description
CROSS-REFERENCE TO RELATED APPLICATION
This application is related to and claims priority from Japanese Patent Application No. Hei. 10-350309 filed on Dec. 9, 1998, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a decompression device-integrated heat exchanger in which a pressure-reducing unit and a heat-exchanging unit of a refrigerant cycle are integrated. In the heat-exchanging unit, high-pressure refrigerant before being decompressed in the pressure-reducing unit is heat-exchanged with low-pressure refrigerant after being decompressed in the pressure-reducing unit. The decompression device-integrated heat exchanger is suitably used for a supercritical refrigerant cycle in which pressure of high-pressure refrigerant discharged from a compressor exceeds the critical pressure of refrigerant.
2. Description of Related Art
In a conventional refrigerant cycle, an enthalpy difference between an inlet side and an outlet side of an evaporator is enlarged by setting the enthalpy of refrigerant at the inlet side of the evaporator to be smaller, so that refrigerant capacity of the refrigerant cycle is improved. However, in this case, an inner heat-exchanging unit is need for performing heat exchange between high-pressure refrigerant and low-pressure refrigerant. Therefore, a new attachment space and a mounting step for mounting the inner heat-exchanging unit are necessary.
SUMMARY OF THE INVENTION
In view of the foregoing problems, it is an object of the present invention to provide a decompression device-integrated heat exchanger in which a pressure-reducing unit and a heat-exchanging unit are integrated, while coefficient of performance of a refrigerant cycle is improved.
According to the present invention, a decompression device-integrated heat exchanger for a refrigerant cycle includes a pressure-reducing unit for reducing pressure of refrigerant in the refrigerant cycle, and a heat-exchanging unit integrated with the pressure-reducing unit, for performing heat-exchange between high-pressure refrigerant before being decompressed in the pressure-reducing unit and low-pressure refrigerant after being decompressed in the pressure-reducing unit. The heat-exchanging unit includes a first tube through which the high-pressure refrigerant flows, and a second tube through which the low-pressure refrigerant flows. The first and second tubes are disposed to be wound around a case of the pressure-reducing unit while the first and second tubes are contact. Thus, in the decompression device-integrated heat exchanger, the case of the pressure-reducing unit is used as an inner solid member of the first and second tubes. As a result, even when exterior force is applied to the first and second tubes, the tubes are prevented from being bent and deformed.
Preferably, the second tube is disposed between the case and the first tube. Therefore, low-pressure refrigerant flowing through the second tube is heat-exchanged with high-pressure refrigerant flowing through the first tube and refrigerant within the case of the pressure-reducing unit. Therefore, coefficient of performance of the refrigerant cycle is further improved.
Preferably, the first tube has a first contacting portion contacting the second tube, and the first contacting portion has a wall thickness thinner than that of the other portion of the first tube. Similarly, the second tube has a second contacting portion contacting the first tube, and the second contacting portion has a wall thickness thinner than that of the other portion of the second tube. Because the first and second contacting portions of the first and second tubes are not exposed outside, the first and second contacting portions are hardly corroded. Thus, the weight of the heat-exchanging unit is reduced while corrosion of the tubes is prevented. Further, because each wall thickness of the contacting portions of the tubes is made thinner, heat-exchanging performance between high-pressure refrigerant and low-pressure refrigerant can be improved.
BRIEF DESCRIPTION OF THE DRAWINGS
Additional objects and advantages of the present invention will be more readily apparent from the following detailed description of a preferred embodiment when taken together with the accompanying drawings, in which:
FIG. 1
is a schematic view of a supercritical refrigerant cycle according to a preferred embodiment of the present invention;
FIG. 2
is a sectional view of a decompression device-integrated heat exchanger according to the embodiment;
FIG. 3A
is a side view taken from arrow IIIA in
FIG. 2
, and
FIG. 3B
is a sectional view of both tubes; and
FIG. 4
is a side view taken from arrow IV in FIG.
2
.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENT
A preferred embodiment of the present invention will be described hereinafter with reference to
FIGS. 1-4
. In the embodiment, a decompression device-integrated heat exchanger in which a pressure-reducing unit
300
and an inner heat-exchanging unit
600
are integrated is typically applied to a supercritical refrigerant cycle.
As shown in
FIG. 1
, the refrigerant cycle includes a compressor
100
for compressing refrigerant (e.g., CO
2
refrigerant), a radiator
200
for cooling refrigerant by performing heat exchange between refrigerant and outside air, an oil separator
110
for separating lubricating oil and refrigerant discharged from the compressor
100
, the pressure-reducing unit (pressure control valve)
300
for decompressing pressure of refrigerant from the radiator
200
, an evaporator
400
for cooling air by evaporating refrigerant decompressed in the pressure-reducing unit
300
, an accumulator
500
, and the heat-exchanging unit
600
integrated with the pressure-reducing unit
300
.
The compressor
100
is driven by a vehicle engine, for example, to compress refrigerant. Refrigerant containing the lubricating oil is separated in the oil separator
110
, so that separated refrigerant flows toward the radiator
200
and separated lubricating oil is returned into the compressor
100
. An opening degree of the pressure-reducing unit
300
is adjusted based on refrigerant temperature on an outlet side of the radiator
200
so that pressure of refrigerant on the outlet side of the radiator
200
is controlled. Refrigerant flowing from the evaporator
400
is separated into gas refrigerant and liquid refrigerant in the accumulator
500
, so that liquid refrigerant is temporarily stored in the accumulator
500
and gas refrigerant flows into the compressor
100
after being heat-exchanged with high-pressure refrigerant in the inner heat-exchanging unit
600
. In
FIG. 1
, the heat-exchanging unit
600
and the pressure-reducing unit
300
are indicated separately; however, the heat-exchanging unit
600
and the pressure-reducing unit
300
are integrated from each other as shown in FIG.
2
. In the heat-exchanging unit
600
, low-pressure refrigerant flowing from the accumulator
500
, having been decompressed in the pressure-reducing unit
300
, is heat exchanged with high-pressure refrigerant from the radiator
200
before being decompressed in the pressure-reducing unit
300
.
In the embodiment of the present invention, the heat-exchanging unit
600
and the pressure-reducing unit
300
are integrated to form the decompression device-integrated heat exchanger. As shown in
FIG. 2
, a control valve
310
of the pressure-reducing unit
300
includes a temperature-sensing portion in which an inner pressure is changed in accordance with refrigerant temperature at the outlet side of the radiator
200
. The control valve
310
is operatively linked with the temperature sensing portion so that an opening degree of a valve opening
312
of the pressure-reducing unit
300
is adjusted in accordance with the variation in the inner pressure of the temperature-sensing portion. The control valve
310
is accommodated in an approximately cylindrical case
330
of the pressure-reducing unit
300
.
The case
330
includes a casing body portion
332
defining a first refrigerant outlet
331
being connected to an inlet side of the evaporator
400
, and a cover portion
334
defining a first refrigerant inlet
333
being connected to the outlet side of the radiator
200
. The control valve
310
is inserted into the casing body portion
332
to be fixed to the casing body portion
332
. After the control valve
310
is inserted into the casing body portion
332
, the cover portion
334
is connected to the casing body portion
332
to close opening of the casing body portion
332
.
Further, the cover portion
334
of the case
330
has a second refrigerant outlet
335
connected to a refrigerant inlet side of the inner heat-exchanging unit
600
, and a second refrigerant outlet
336
connected to a refrigerant outlet side of the inner heat-exchanging unit
600
. Further, the second refrigerant outlet
335
communicates with the first refrigerant inlet
333
, and the second refrigerant inlet
336
communicates with a refrigerant upstream side of the valve opening
312
.
Within the case
330
, a first refrigerant passage (temperature sensing chamber)
337
is formed from the first refrigerant inlet
333
to the second refrigerant outlet
335
, and a second refrigerant passage
338
is formed from the second refrigerant inlet
336
to the valve opening
312
.
The temperature sensing portion of the control valve
310
is provided in the first refrigerant passage
337
to detect the refrigerant temperature at the outlet side of the radiator
200
. The temperature sensing portion includes a diaphragm (pressure-response member)
311
a,
a diaphragm cover
311
b
for defining a sealed space
311
c
with the diaphragm
311
a,
and a diaphragm support
311
d
for supporting and fixing the diaphragm
311
a.
The diaphragm
311
a
is inserted between the diaphragm cover
311
b
and the diaphragm support
311
d.
Refrigerant is sealed within the sealed space
311
c
by a density (e.g., 625 kg/m
3
) in a range between the saturated liquid density at the refrigerant temperature of 0° C. and the saturated liquid density at the critical point. On the other hand, onto a side of the diaphragm
311
a
opposite to the sealed space
311
c,
pressure of the second refrigerant passage
338
is introduced through a pressure introduction passage
311
e.
Refrigerant is sealed within the sealed space
311
c
from a sealed pipe
311
f.
The sealed pipe
311
f
is made of metal having a high heat-transmitting performance such as copper, so that the refrigerant temperature within the sealed space
311
c
is changed immediately relative to a change of the refrigerant temperature in the first refrigerant passage
337
.
The opening degree of the valve opening
312
is adjusted by a valve body
313
. The valve body
313
is connected to the diaphragm
311
a
to be mechanically operated with the inner pressure of the sealed space
311
c.
For example, as the inner pressure of the sealed space
311
c
increases, the valve body
313
is moved to reduce the opening degree of the valve opening
312
. Further, a spring
314
is disposed so that elastic force is applied to the valve body
313
in a direction for reducing the opening degree of the valve opening
312
. Thus, the valve body
313
is moved in accordance with a balance between the elastic force of the spring
314
, and a pressure difference of the inside and outside of the sealed space
311
c.
An initial setting load of the spring
314
is adjusted by turning an adjustment nut
315
. The initial setting load of the spring
314
is set in such a manner that refrigerant has a predetermined super cooling degree (e.g., approximately 10° C.) in a condensing area below the critical pressure. Specifically, the initial setting load of the spring
314
is approximately 1 MPa when being converted to pressure within the sealed space
311
c.
A spring seat
315
a
is disposed between the spring
314
and the adjustment nut
315
to prevent the spring
314
and the adjustment nut
315
are directly rubbed.
In the supercritical area, the pressure-reducing unit
300
controls the refrigerant pressure at the outlet side of the radiator
200
based on the refrigerant temperature at the outlet side of the radiator
200
along the isopycnic line of 625kg/m
3
. on the other hand, in the condensing area, the pressure-reducing unit
300
controls the refrigerant pressure at the outlet side of the radiator
200
so that the super-cooling degree of the refrigerant at the outlet side of the radiator
200
becomes a predetermined value.
The inner heat-exchanging unit
600
includes a flat-like high-pressure tube
610
having therein plural passages through which high-pressure refrigerant flows, and a flat-like low-pressure tube
620
having therein plural passages through which low-pressure refrigerant flows. As shown in
FIG. 3A
, both the tubes
610
,
620
are wound around the case
330
in a contacting state while being overlapped in a radial direction of the case
330
. The tubes
610
,
620
are connected to the case
330
by brazing the contacting surfaces therebetween. Each of the tubes
610
,
620
is formed by extrusion or drawing of an aluminum material. In each of the tubes
610
,
620
, a wall thickness t
1
at a position where the tubes
610
,
620
are made contact is set to be thinner than a wall thickness t
2
of the other position.
As shown in
FIG. 3A
, a refrigerant inlet of the high-pressure tube
610
is bonded to a first joint pipe
631
by brazing, a refrigerant outlet of the high-pressure tube
610
is bonded to a second joint pipe
632
by brazing, and both the joint pipes
631
,
632
are brazed to a joint block
630
fixed to the pressure-reducing unit
300
.
As shown in
FIG. 2
, the joint block
630
includes a block body portion
630
a
connected to both the joint pipes
631
,
632
, and a cap portion
630
b
for closing a part of the first refrigerant passage
337
and the second refrigerant passage
338
formed in the block body portion
630
a.
The block body portion
630
a
and the cap portion
630
b
are fixed to the case
330
of the pressure-reducing unit
300
by hexagon bolts
630
c
each having a hole therein.
Round rings
630
d
are disposed to prevent refrigerant from leaking from a clearance between the block body portion
630
a
and the cap portion
630
b.
Further, as shown in
FIG. 3A
, a refrigerant inlet and a refrigerant outlet of the low-pressure tube
620
are brazed to third and fourth joint pipes
621
,
622
shown in
FIG. 4
, respectively. The third and fourth joint pipes
621
,
622
are disposed so that a refrigerant flow direction in the low-pressure tube
620
and a refrigerant flow direction in the high-pressure tube
610
are reverse to each other. The third and fourth joint pipes
621
are connected to refrigerant pipes through union portions
621
a,
622
a,
respectively.
According to the present invention, both the tubes
610
,
620
are wound around the case
330
while adjacent two of the case
330
and the tubes
610
,
620
contact. Therefore, even when exterior force is applied to the tubes
610
,
620
, the tubes
610
,
620
are prevented from being bent and deformed, because the case
330
of the pressure-reducing unit
300
is used as an inner solid member. Further, because the low-pressure tube
620
is placed between the casing
330
and the high-pressure tube
610
, refrigerant flowing through the low-pressure tube
620
is heat-exchanged with refrigerant flowing through the high-pressure tube
610
and refrigerant flowing through the first refrigerant passage
337
and the second refrigerant passage
338
of the pressure-reducing unit
300
. Thus, an enthalpy difference between the inlet side and the outlet side of the evaporator
400
is further enlarged, and the refrigerant capacity and coefficient of performance of the refrigerant cycle can be further improved.
Each wall thickness of the tubes
610
,
620
is necessary to be determined based on corrosion in addition to the pressure of refrigerant flowing though the tubes
610
,
620
. However, because the contacting portion on which both the tubes
610
,
620
contact is not exposed by outside air, the corrosion is hardly caused in the contacting portion between the tubes
610
,
620
. Thus, in the embodiment of the present invention, the wall thickness t
1
of the contacting portion is made thinner than the wall thickness t
2
of the other portion in each of the tubes
610
,
620
. As a result, the weight of the tubes
610
,
620
can be reduced.
Although the present invention has been fully described in connection with the preferred embodiment thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art. For example, in the above-described embodiment, both the tubes
610
,
620
are wound around the case
330
while both the tubes
610
,
620
are made contact. However, both the tubes
610
,
620
can be directly brazed to the case
330
using a tube clad by brazing material on both side surfaces. In this case, manufacturing step can be made simple, and sealing performance is improved without using a seal member such as a ring.
In the above-described embodiment, the present invention is typically applied to the supercritical refrigerant cycle using CO
2
refrigerant. However, the present invention may be applied to a supercritical refrigerant cycle using refrigerant such as ethylene, ethane, or nitrogen oxide. Further, the present invention may be applied to a normal refrigerant cycle using flon as refrigerant, or may be applied to a heat pump.
In the above-described embodiment, the low-pressure tube
620
is placed between the high-pressure tube
610
and the case
330
. However, the high-pressure tube
610
may be placed between the low-pressure tube
620
and the case
330
.
In the above-described embodiment, one of the tubes
610
,
620
contacts the case
330
, while both the tubes
610
,
620
are overlapped in the radial direction of the case
330
. However, the tubes
610
,
620
may contact the case
330
to be arranged in an axial direction (longitudinal direction) of the casing
330
. Further, each of the tubes
610
,
620
may be formed into the other shape such as a simple round shape.
In the above-described embodiment, in each of both the tubes
610
,
620
, the wall thickness t
1
of the contacting position is made thinner than the wall thickness t
2
of the other position. However, the wall thickness of any one contacting position may be set to be thinner than that of the other position.
Further, the structure of the pressure-reducing unit
300
is not limited to the above-described embodiment. The present invention may be applied to a thermal expansion valve used for a normal flon refrigerant cycle.
Such changes and modifications are to be understood as being within the scope of the present invention as defined by the appended claims.
Claims
- 1. A decompression device-integrated heat exchanger for a refrigerant cycle, comprising:a pressure-reducing unit for reducing pressure of refrigerant in the refrigerant cycle; and a heat-exchanging unit integrated with said pressure-reducing unit, for performing heat-exchange between high-pressure refrigerant before being decompressed in said pressure-reducing unit and low-pressure refrigerant after being decompressed in said pressure-reducing unit, wherein: said heat-exchanging unit includes a first tube through which the high-pressure refrigerant flows, and a second tube through which the low-pressure refrigerant flows; said pressure-reducing unit has a case for defining a refrigerant passage therein; and said first and second tubes are disposed to be wound around said case while said first and second tubes are made contact.
- 2. The decompression device-integrated heat exchanger according to claim 1, wherein said second tube is disposed between said case and said first tube.
- 3. The decompression device-integrated heat exchanger according to claim 1, wherein:said first tube has a first contacting portion contacting said second tube; and said first contacting portion has a wall thickness thinner than that of the other portion of the first tube.
- 4. The decompression device-integrated heat exchanger according to claim 1, wherein:said second tube has a second contacting portion contacting said first tube; and said second contacting portion has a wall thickness thinner than that of the other portion of the second tube.
- 5. The decompression device-integrated heat exchanger according to claim 1, wherein:said case has an approximate cylindrical shape; and said first and second tubes are disposed to be overlapped in a radial direction of said case while contacting said case.
- 6. The decompression device-integrated heat exchanger according to claim 1, wherein said pressure-reducing unit is for reducing pressure more than a critical pressure of refrigerant discharged from a compressor of the refrigerant cycle.
- 7. The decompression device-integrated heat exchanger according to claim 1, wherein said first and second tubes are directly bonded to said case by brazing.
- 8. The decompression device-integrated heat exchanger according to claim 2, wherein said second tube has both wall surfaces clad by a brazing material.
- 9. A refrigerant cycle comprising:a compressor for compressing and discharging refrigerant; a radiator for cooling refrigerant discharged from said compressor; a decompression device-integrated heat exchanger for reducing pressure of refrigerant from said radiator and for performing heat-exchange between refrigerant before being decompressed and refrigerant after being decompressed; and an evaporator for evaporating refrigerant after being decompressed, wherein: said decompression device-integrated heat exchanger includes a pressure-reducing unit in which pressure of refrigerant from said radiator is reduced, a case for accommodating said pressure-reducing unit, a first tube through which the refrigerant from said radiator flows, and a second tube through which refrigerant from said evaporator flows; and said first and second tubes are disposed to be connected to said case while said first and second tubes are made contact.
- 10. The refrigerant cycle according to claim 9, wherein said first and second tubes are wound around said case.
- 11. The refrigerant cycle according to claim 10, wherein said second tube is disposed between said case and said first tube.
- 12. The refrigerant cycle according to claim 10, wherein said first tube is disposed between said case and said second tube.
- 13. The refrigerant cycle according to claim 9, wherein:said first tube has a first contacting portion contacting said second tube; and said first contacting portion has a wall thickness thinner than that of the other portion of the first tube.
- 14. The refrigerant cycle according to claim 9, wherein:said second tube has a second contacting portion contacting said first tube; and said second contacting portion has a wall thickness thinner than that of the other portion of the second tube.
- 15. The refrigerant cycle according to claim 9, wherein:said case has an approximate cylindrical shape; and said first and second tubes are disposed to be overlapped in a radial direction of said case while contacting said case.
- 16. The refrigerant cycle according to claim 9, wherein the pressure of refrigerant discharged from said compressor is more than a critical pressure of refrigerant.
- 17. The refrigerant cycle according to claim 9, wherein said first and second tubes are directly connected to said case by brazing.
Priority Claims (1)
Number |
Date |
Country |
Kind |
10-350309 |
Dec 1998 |
JP |
|
US Referenced Citations (4)