Refrigeration – Automatic control – Refrigeration producer
Reexamination Certificate
2002-07-02
2003-10-28
Norman, Marc (Department: 3744)
Refrigeration
Automatic control
Refrigeration producer
C062S228400, C062S196400
Reexamination Certificate
active
06637226
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a constant-temperature liquid circulating apparatus which supplies constant-temperature liquid to a load to circulate the same.
PRIOR ART
FIG. 3
shows one example of a constant-temperature liquid circulating apparatus which has been already proposed, and a constant-temperature liquid circulating apparatus
101
comprises a refrigerating circuit section
103
for cooling constant-temperature liquid whose temperature has been elevated in a load
2
, a constant-temperature liquid circuit section
104
which, after adjusting the temperature of the constant-temperature liquid which has been cooled by refrigerant of the refrigerating circuit section
103
to a predetermined temperature, supplies the adjusted constant-temperature liquid circuit section
104
to the load
2
to circulate the same, and a control section
105
which controls the temperature of the constant-temperature liquid supplied to the load
2
.
The refrigerating circuit section
3
is constituted by connecting a compressor
7
which compresses proper refrigerant to produce refrigerant gas with a high temperature and a high pressure, a condenser
8
which cools and condenses the refrigerant gas to produce liquid refrigerant with a high pressure, a decompressor
9
which decompresses liquid refrigerant to temperature-reduce the same, and an evaporator
10
which evaporates the liquid refrigerant which has been pressure-reduced in the decompressor
9
in this order in series.
The constant-temperature liquid circuit section
104
comprises a tank
24
for constant-temperature liquid, a heat exchanger
25
which cools the constant-temperature liquid whose temperature has been elevated in the load
2
, a heater unit
26
which has a heater
27
heating the constant-temperature liquid which has been cooled in the heat exchanger
25
up to a predetermined temperature, a pump
28
which supplies the constant-temperature liquid in the tank
24
whose temperature has been adjusted to the predetermined temperature by the heater
27
to the load
2
to circulate the same and a level switch
29
which detects a liquid level of the constant-temperature liquid in the tank
24
; and all of the heat exchanger
25
, the heater unit
26
and the pump
28
are assembled to the tank
24
. Also, a cylindrical heater cover
30
with a bottom which surrounds the heater
27
and whose upper portion can be opened is provided around an outer periphery of the heater
27
.
The control section
105
is for controlling the entire apparatus, and it comprises a temperature controller
42
which outputs a necessary signal according to a temperature signal of a temperature sensor
37
, a programmable controller (hereinafter, abbreviated as PLC)
43
which outputs a necessary signal according to signals of the level switch
29
in the tank
24
, a low pressure cut switch
39
and a refrigerant high pressure cut switch
20
, an electromagnetic contactor/electromagnetic switch
44
which controls operations of the compressor
7
and the pump
28
, current flow to the heater
27
and an injection valve
16
according to signals output from the temperature controller
42
and the PLC
43
, and an operation displaying panel
45
which performs necessary displaying.
Since the constant-temperature liquid circulating apparatus
101
cools constant-temperature liquid whose temperature has been elevated in the load
2
by the heat exchanger
25
and heats the cooled constant-temperature liquid by the heater
27
to produce a constant-temperature liquid with a predetermined temperature, it is made easy to conduct a temperature adjustment of the constant-temperature liquid.
However, since the constant-temperature liquid circulating apparatus
101
heats the constant-temperature liquid which has been cooled in the heat exchanger
25
by the heater
27
, the amount of power required for an operation is increased. In particular, according to the operation condition of the circulating apparatus
101
, such a phenomenon that the compressor
7
, the pump
28
and the heater
27
are made conductive simultaneously occurs, and it is necessary to increase the allowance amount of current conduction to the circulating apparatus
101
in order to respond to this phenomenon, and an equipment cost for current conduction is also increased.
As an apparatus which has solved such a problem, there is a constant-temperature liquid circulating apparatus shown in FIG.
4
.
A constant-temperature liquid circulating apparatus
91
shown in
FIG. 4
comprises a constant-temperature liquid circuit section
93
which cools constant-temperature liquidcirculating from a load
2
to a predetermined temperature to supply the same to the load
2
, a refrigerating circuit section
92
for cooling the constant-temperature liquid, and a control section
94
for controlling the temperature of the constant-temperature liquid supplied to the load
2
.
The refrigerating circuit section
92
comprises a main circuit section
50
provided with a compressor
7
, a condenser
8
, a first electronic expansion valve
56
, an evaporator
10
and a piping connecting theses members in series; a pressure sensor
61
and a temperature sensor
62
provided in the main circuit section
50
; a hot gas circuit section
58
provided with a second electronic expansion valve
59
which supplies a portion of refrigerant with a high temperature bypassing the condenser
8
and the first electronic expansion valve
56
to be discharged from the compressor
7
to the evaporator
10
; and a circulating circuit
12
provided with an electronic expansion valve
57
.
The constant-temperature liquid circuit section
93
comprises a tank
24
for constant-temperature liquid, an overflow tank
64
in the tank
24
, a heat exchanger
25
which cools constant-temperature liquid circulated from the load
2
in the evaporator
10
, a temperature sensor
37
which detects the temperature of constant-temperature liquid, a level switch
29
, and a pump
28
which supplies constant-temperature liquid whose temperature has been adjusted to a predetermined temperature to the load
2
to circulate the same.
The control section
94
comprises a PLC
43
, an electromagnetic contactor/electromagnetic switch
67
, an operation display panel
45
, and an expansion valve controller
96
, and the expansion valve controller
96
controls the opening degrees of the electronic expansion valves
56
,
57
and
59
individually to adjust constant-temperature liquid to a predetermined temperature by the signals from the temperature sensor
37
,
62
and the pressure sensor
61
.
Then, in the constant-temperature liquid circulating apparatus
91
shown in
FIG. 4
, since the opening degrees of the first and second electronic expansion valves
56
,
59
are controlled by the control section
94
to control the refrigerating capacity of the refrigerating circuit section
92
so that the temperature of the constant-temperature liquid supplied to the load
2
can be controlled accurately, the heater
27
for preparing constant-temperature liquid with a predetermined temperature, which is provided in the constant-temperature liquid circulating apparatus
1
shown in
FIG. 3
is made unnecessary.
However, since the constant-temperature liquid circulating apparatus
91
shown in
FIG. 4
controls the refrigerating capacity of the refrigerating circuit section
92
by only controlling the opening degrees of the first and second electronic expansion valves
56
,
59
, a time required for reaching a target temperature is short, but it may not be said that controllability to disturbances (change in flow rate of constant-temperature liquid, change in external thermal load, change in temperature of cooling water in the condenser and the like) is good.
DISCLOSURE OF THE INVENTION
A ploblem to be solved by the invention is to provide a constant-temperature liquid circulating apparatus which is of an energy saving type, whose time required for reaching a target temperature is short, whose controllability to distu
Sueoka Yoshiaki
Watanabe Mitsuhiro
Norman Marc
SMC Corporation
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