Refrigeration – Automatic control – Of external fluid or means
Reexamination Certificate
2000-12-07
2002-02-26
Tapolcai, William E. (Department: 3744)
Refrigeration
Automatic control
Of external fluid or means
C062S435000
Reexamination Certificate
active
06349552
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a temperature control device for a constant temperature chiller unit which provides thermal medium fluid such as cold water of constant temperature toward a semiconductor manufacturing device, a laser machine, or miscellaneous scientific or chemical instruments in a fluid circulating mode, and to a temperature control device for an automatic vending machine which stores articles therein and can change itself into a cooling mode and heating mode in relation to the season or other conditions.
In the prior constant temperature chiller unit, thermal medium fluid such as pure water or “fluorinert” (supplied by 3M corporation) is supplied through a refrigerating system comprised of a compressor, a condenser and an evaporator for fron gas (Freon gas). In this process, high temperature fron gas compressed by a compressor is liquidized by a condenser into liquid fron, and the liquid fron absorbs heat from the surroundings when it is evaporated by an evaporator, whereby produced is a temperature medium fluid such as low temperature pure water or “fluorinert”.
When the range of the allowable temperature is limited in a small range, such as in a semiconductor manufacturing device which requires an accurate setting of plus and minus 1 degree C., if the refrigerator (evaporator) is operated at a maximum power for cooling, the temperature of the thermal medium fluid goes down too low, thereby being overcooled. For compensating this problem, a constant temperature tank having a buffer capacity of three to five times of cold water flow per minute is disposed, and the tank is provided with an electrical heater for controlling the temperature. Then, extra electrical power is necessary, whereby the overall size of the apparatus becomes large and additional cost for setting and operation becomes necessary.
Referring to
FIG. 8
, there is shown a constant temperature tank with a heater of prior art. The constant temperature tank
16
produces cold water by a refrigerating circuit
1
comprised of a compressor
12
, a condenser
14
and an evaporator
20
. The produced cold water is supplied to the external secondary heat load
24
such as a semiconductor manufacturing device by the pump
22
, and is circulated within the cold water circulating circuit
3
. In the refrigerating circuit
1
, there is provided a dryer
15
, and in the cold water circulating circuit
3
, there are provided a pressure controller
17
, a relief valve
19
and pressure gauge G. Within the constant temperature tank
16
, there are provided a sensor for detecting overheating and freezing, and a sensor for detecting water level of the tank. Each sensor is connected to an overheat and freezing monitor (arrow A) and to a water level monitor (arrow B), respectively. To the bottom of the tank
16
, a drain circuit
28
is connected and a drain valve
29
is disposed for controlling the drain port (arrow C).
Thus, high temperature fron gas (refrigerant) compressed by a compressor
12
in the refrigerating system is liquidized by a condenser
14
into liquid fron, and the liquid fron absorbs heat from the surroundings when it is evaporated by the evaporator
20
, whereby cold water is produced. On the other hand, the condenser
14
is exposed to high temperature. For cooling the condenser
14
, a cooling circuit
2
comprised of a water cooling type cooler
26
is provided. The cooler
26
is cooled by any of cooling tower water, factory circulating water or underground water. In this circuit
2
, cooling water is circulated by operating a flow switch
25
and a control valve
27
, so that the condenser
14
is cooled.
However, when the range of the allowable temperature is limited in a small range, such as in a semiconductor manufacturing device, if the evaporator
20
(refrigerator) is operated at a maximum power for cooling, the temperature of the thermal medium fluid goes down too low, thereby being overcooled. For compensating this problem, an electrical heater
50
is attached to the constant temperature tank
16
for controlling its temperature. The heater
50
is also used for raising the temperature of thermal medium fluid during its starting mode. As a result, extra electrical power is required, whereby an additional cost is required.
In other methods for controlling the temperature, a hot gas bypass method and a refrigerator ON and OFF method are known. However, in the former method, cooling and heating should be alternately exchanged, whereby the response of temperature control is poor and the bypass valve is not reliable so that it often fails. In the latter method, a large capacity buffer tank should be disposed, so that the overall size becomes larger and the accuracy of the temperature control becomes poor.
In an automatic vending machine which can change itself into a cooling mode and heating mode in relation to the season, a powerful heater is inevitable. Accordingly, extra electrical power is required and thus an additional cost is required.
Japanese unexamined patent publication No. Hei 9-72644 entitled “Cold water circulation supply machine for scientific and chemical machines” and Japanese unexamined patent publication No. Hei 9-196512 entitled “Cooling liquid supply device” relate to a constant temperature chiller unit as a cold water supply device.
SUMMARY OF THE INVENTION
It is a first object of the present invention to provide a temperature control device for thermal medium fluid in which an electrical heater is eliminated from the constant temperature tank thereby reducing the electrical power so that it can improve the accuracy and response of the device.
It is a second object of the present invention to provide a temperature control device for thermal medium fluid in which the constant temperature tank is eliminated thereby reducing the overall size of the device.
It is a third object of the present invention to provide a temperature control device for thermal medium fluid in which the working range is extended from −40 degree C. to 60 degree C. relative to the prior art.
It is a fourth object of the present invention to provide a temperature control device for thermal medium fluid in which the electrical power in a starting mode is considerably reduced.
It is a fifth object of the present invention to provide a power saving type temperature control device for an automatic vending machine which stores articles therein and can change itself into a cooling mode and heating mode in relation to the season or other conditions.
A first object of the present invention is achieved by the device in which a heat exchanger is interposed within a compression circuit between a compressor and a condenser so that the compression circuit becomes a primary circuit of the heat exchanger, and a bypass circuit is disposed at the downstream side of a pump. Through the bypass circuit, thermal medium fluid passes through a secondary circuit of the heat exchanger toward a circulation circuit, and fluid flow in the bypass circuit is controlled by a flow control valve. Heated thermal medium fluid by the heat exchanger is introduced into the circulation circuit. Thus, the temperature of thermal medium fluid supplied to an external secondary heat load is controlled.
Based upon above characteristics of the first embodiment of the invention, a part of the heat of the high temperature fron gas compressed by the compressor is given to the thermal medium fluid (water) which is supplied to the external secondary heat load so that the temperature of the overcooled thermal medium fluid (cold water) cooled by the regrigerating circuit is raised and controlled within a predetermined temperature range. Thus, the accuracy and response of the device are improved. Since the electrical heater in the prior art is eliminated, the electrical power and cost are reduced.
The second object of the present invention is achieved by the device in which the evaporator is comprised of multi-tube type cylindrical evaporator and this cylindrical evaporator works as the constant temperature tank. Th
Ryu Hideo
Sakamoto Yasushi
Shimoda Kazuyoshi
Sugiyama Motoharu
Takikawa Kazunori
Ali Mohammad M.
Tapolcai William E.
Usui Kokusai Sangyo Kaisha Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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