Temperature control apparatus

In a temperature control apparatus for controlling the temperature of a load by supplying high-temperature circulating liquid to the load, a device in which a helical channel portion of a first heat exchange channel through which circulating liquid flows is housed in a second heat exchange channel formed of a channel space in a hollow shell through which coolant flows is used as a heat exchanger for cooling the circulating liquid, cylindrical members are individually fitted on an inflow channel portion and an outflow channel portion connected to opposite ends of the helical channel portion of the first heat exchange channel, and the cylindrical members are each fixed to the shell of the heat exchanger with a weld.

TECHNICAL FIELD

The present invention relates to temperature control apparatuses that control the temperature of a load to a desired temperature by supplying circulating liquid whose temperature is regulated to the load, and in particular, to a temperature control apparatus suitable for controlling the temperature of the load to a high temperature.

BACKGROUND ART

Temperature control apparatuses for controlling the temperature of a load by supplying temperature-regulated circulating liquid to the load are widely known, as disclosed in PTL 1 and PTL 2, for example. The temperature control apparatuses disclosed in such patent literatures include a circulating liquid circuit for circulating the circulating liquid to and from the load and a cooling circuit for cooling the circulating liquid, which are arranged in parallel and connected to each other via tanks and valves.

Some semiconductor manufacturing apparatuses require to control the temperature of the load to a temperature significantly above the boiling point of water (100° C.) under atmospheric pressure, as disclosed in PTL 2, for example. In such temperature control apparatuses, for example, the temperature of the circulating liquid changes significantly or the difference in temperature between the circulating liquid and the cooling liquid increases significantly in controlling the temperature of the circulating liquid. For that reason, a design that takes into account the use of the circulating liquid at high temperatures should be required.

However, it can be hardly said that known apparatuses take sufficient measures against using the circulating liquid at high temperatures. This leads to a strong demand for development of a temperature control apparatus designed especially for high temperature use of the circulating liquid.

Patent Literature

SUMMARY OF INVENTION

Technical Problem

A technical problem of the present invention is to provide a temperature control apparatus designed especially for high temperature use of circulating liquid in controlling the load at high temperatures.

Solution to Problem

To solve the above technical problem, a temperature control apparatus according to the present invention is a temperature control apparatus for controlling an external load to a predetermined high temperature by regulating circulating liquid having a boiling point higher than 100° C. to a temperature higher than 100° C. and supplying the circulating liquid to the load, wherein the temperature control apparatus includes a tank storing circulating liquid and including a heater for heating the circulating liquid, a discharge channel connecting the tank and a circulating-liquid ejection port for discharging the circulating liquid to the load, a circulation pump that pumps the circulating liquid from the tank to the discharge channel, a return channel connecting a circulating-liquid return port that receives the circulating liquid returned from the load and the tank, a heat exchanger including a first heat exchange channel through which the circulating liquid flows and a second heat exchange channel through which coolant for cooling the circulating liquid in the first heat exchange channel, a cooling circulation forward path for supplying the circulating liquid from the tank to the first heat exchange channel of the heat exchanger, a cooling circulation reverse path for returning the circulating liquid cooled by the heat exchanger from the first heat exchange channel to the tank, a coolant supply path for introducing the coolant to the second heat exchange channel of the heat exchanger, and a coolant discharge path for discharging the coolant after the heat exchange from the second heat exchange channel. In the heat exchanger, the first heat exchange channel includes a helical channel portion extending in a helical form along an axis, an inflow channel portion connected to one end of the helical channel portion and including a circulating-liquid inlet, and an outflow channel portion connected to the other end of the helical channel portion and including a circulating-liquid outlet, and the second heat exchange channel is a channel space formed in a hollow shell. The helical channel portion of the first heat exchange channel is housed in the second heat exchange channel in the shell, the inflow channel portion and the outflow channel portion are let out from the shell, the cooling circulation forward path is connected to the circulating-liquid inlet, and the cooling circulation reverse path is connected to the circulating-liquid outlet. The coolant supply path communicates with the second heat exchange channel through a coolant inlet provided on the shell, and the coolant discharge path communicates with the second heat exchange channel through a coolant outlet provided on the shell.

In this case, preferably, cylindrical members made of metal are individually fitted on the inflow channel portion and the outflow channel portion of the first heat exchange channel made of a metal pipe, wherein the shell made of metal includes a pair of mounting openings for letting the inflow channel portion and the outflow channel portion out from the shell and for mounting the cylindrical members fitted on the channel portions into the shell from the outside, and wherein, at the mounting openings, outer peripheries of the cylindrical members are fixed to the shell by welding. More preferably, the cylindrical members fitted on the inflow channel portion and the outflow channel portion each include a cylindrical body made of metal and a ring-shaped sealing member made of metal disposed on an inner periphery of the cylindrical body to seal an outer periphery of the channel portion, wherein an outer periphery of the cylindrical body is welded to the shell in a ring shape.

More preferably, the cylindrical body includes a fixing cylindrical portion fixed to the shell by the welding and a sealing cylindrical portion having the ring-shaped sealing member on the inner periphery thereof, wherein the sealing cylindrical portion is fastened to the fixing cylindrical portion by screwing, and wherein the ring-shaped sealing member is acutely angled at an end edge adjacent to the fixing cylindrical portion, wherein, when the sealing cylindrical portion is screwed to the fixing cylindrical portion, the end edge of the ring-shaped sealing member is brought into pressure-contact with each of the outer peripheries of the inflow channel portion and the outflow channel portion into a bitten state by pressure of the sealing cylindrical portion.

In the temperature control apparatus according to the present invention, preferably, in the shell, the coolant outlet to which the coolant discharge path is connected is disposed at one axial end at which the inflow channel portion is disposed, and the coolant inlet to which the coolant supply path is connected is disposed at the other axial end at which the outflow channel portion is disposed.

In the temperature control apparatus according to the present invention, preferably, the temperature control apparatus includes a discharge-side temperature sensor provided in the discharge channel to measure a temperature of the circulating liquid discharged to the load and a control unit including a temperature setting unit for setting the temperature of the circulating liquid to be discharged to the load, the control unit being for controlling rotational speeds of the circulation pump and the cooling pump based on a measurement result of the discharge-side temperature sensor and a temperature set by the temperature setting unit, wherein the circulation pump is immersed in the circulating liquid in the tank, and wherein the control unit is configured, when the temperature of the circulating liquid set by the temperature setting unit is lower than a predetermined threshold temperature, to maintain the rotational speed of the circulation pump to a low rotational speed, and when the temperature is higher than the predetermined threshold temperature, to maintain the rotational speed of the circulation pump to a high rotational speed.

More preferably, the control unit is configured, when the set temperature is increased by the temperature setting unit, to decrease the rotational speed of the cooling pump once and thereafter gradually increase the rotational speed, and when the set temperature is decreased, to increase the rotational speed of the cooling pump once and thereafter gradually decrease the rotational speed, and when the temperature of the circulating liquid measured by the discharge-side temperature sensor s equal to the set temperature, to maintain the rotational speed at that time.

More preferably, the control unit is configured such that, in increasing the set temperature, the higher the set temperature, the smaller a gradient of a change in the rotational speed of the cooling pump when the rotational speed is decreased once and is thereafter gradually increased, and in decreasing the set temperature, the lower the set temperature, the smaller an gradient of a change in the rotational speed when the rotational speed is increased once and is thereafter gradually decreased.

A pressure regulation unit for regulating the pressure of the coolant flowing through the channel of the coolant may be connected to the channel of the coolant.

Advantageous Effects of Invention

The present invention uses a device in which a helical channel portion of a first heat exchange channel through which circulating liquid flows is housed in a second heat exchange channel formed of a channel space in a hollow shell through which coolant flows as a heat exchanger for cooling the circulating liquid. In a preferable form, cylindrical members are individually fitted on an inflow channel portion and an outflow channel portion connected to opposite ends of the helical channel portion of the first heat exchange channel, and the cylindrical members are each fixed to the shell of the heat exchanger with a weld. This simplifies the structure of the heat exchanger to minimize the welded portions and prevents the occurrence of problems, such as cracks, at the welded portions due to the temperature difference between the circulating liquid and the coolant as much as possible. As a result, the durability of the temperature control apparatus against the use of the high-temperature circulating liquid can be enhanced.

In another preferable form of the present invention, the circulation pump is immersed in the circulating liquid in the tank unit, and when the set temperature of the circulating liquid is higher than a predetermined threshold temperature, the rotational speed of the circulation pump is maintained at a high rotational speed. This allows the temperature of the circulating liquid to be efficiently increased to a set temperature and to be maintained at the temperature also using the heat generated in the circulation pump.

In still another preferable form of the present invention, when the set temperature of the circulating liquid is set from a temperature higher than the threshold temperature to a lower temperature, the rotational speed of the circulation pump is decreased to a lower rotational speed and is maintained at the lower rotational speed, and at the same time, the rotational speed of the cooling pump increases. This allows suppressing the heat generation of the circulation pump and accelerating the cooling of the circulating liquid with the heat exchanger, thereby efficiently decreasing the temperature of the circulating liquid to the set temperature.

In still another preferable form of the present invention, a pressure regulation unit is connected to the coolant channel. Thus, even if the coolant is expanded by boiling or the like as a result of heat exchange with the high-temperature circulating liquid, a problem, such as breakage, in the channel can be prevented by adjusting the pressure of the coolant with the pressure regulation unit.

Thus, according to the present invention and the preferable forms of the present invention, a temperature control apparatus designed especially for using high-temperature circulating liquid in controlling a load to a high temperature can be provided.

DESCRIPTION OF EMBODIMENTS

FIGS.1to4illustrate an embodiment of a temperature control apparatus according to the present invention. The temperature control apparatus1is especially suitable for controlling an external load (not illustrated) to a predetermined high temperature higher than, for example, 100° C., by regulating the temperature of circulating liquid whose boiling point is higher than 100° C. to a temperature higher than 100° C. and supplying the circulating liquid to the load.

The temperature control apparatus1includes a casing10covering the outside of the apparatus1, a tank unit2containing and storing circulating liquid, a circulating-liquid ejection circuit3that discharges the circulating liquid from the tank unit2to an external load (not illustrated) and returns the circulating liquid received from the load to the tank unit2, a circulating-liquid cooling circuit5that cools the circulating liquid discharged from the tank unit2using a heat exchanger4and returns the circulating liquid to the tank unit2, a coolant supply circuit6that introduces coolant to the heat exchanger4and lets out the coolant after exchanging heat with the circulating liquid from the heat exchanger4, and a control unit7that controls, for example, the temperature and the flow rate, of the circulating liquid flowing through the circulating-liquid ejection circuit3and the circulating-liquid cooling circuit5.

The tank unit2, the circulating-liquid ejection circuit3, the heat exchanger4, the circulating-liquid cooling circuit5, the coolant supply circuit6, and the control unit7are housed in the one casing10. A circulating-liquid ejection port11and a circulating-liquid return port12of the circulating-liquid ejection circuit3and a coolant supply port13and a coolant discharge port14of the coolant supply circuit6are provided on the outer peripheral side of the casing10. This allows the pipes of the target apparatus (load) of temperature control on the user side, a coolant chiller, and so on to be connected to these openings (ports)11,12,13, and14.

A drain pan15for receiving leaked circulating liquid and coolant is disposed at the bottom of the casing10. The drain pan15includes a float-type leakage sensor16, which is electrically connected to the control unit7, and a drain port17, which always opens to the outside to discharge the liquid accumulated in the drain pan15to the outside. This allows, for example, when a large amount of circulating liquid or coolant leaks in the apparatus1and the leakage sensor16detects the leakage, a notice of the detection result to be given or the power source of the apparatus1to be turned off.

A suitable example of the circulating liquid is fluorinated liquid with a boiling point of about 200° C. or higher under atmospheric pressure. A suitable example of the coolant is industrial water with a boiling point of 100° C. under atmospheric pressure. In the present embodiment, circulating liquid at 160° C. in the tank unit2is discharged to the external load through the circulating-liquid ejection circuit3, and the circulating liquid at 170° C. after controlling (cooling) the temperature of the load is returned to the tank unit2through the circulating-liquid ejection circuit3. The circulating liquid at 160° C. in the tank unit2is discharged to the circulating-liquid cooling circuit5, is cooled to 100° C. by the heat exchanger4, and is thereafter returned to the tank unit2. For the coolant, a coolant at 25° C. is supplied to the heat exchanger4through the coolant supply circuit6, is heated to 30° C. by exchanging heat with the circulating liquid, and is discharged from the heat exchanger4.

Thus, in the temperature control apparatus1, the circulating-liquid ejection circuit3and the circulating-liquid cooling circuit5are connected in parallel to one tank unit2. In other words, the circulating-liquid ejection circuit3, which discharges the circulating liquid to the load (the target of temperature control), receives the circulating liquid heated by exchanging heat with the load, and returns the circulating liquid to the tank unit2, and the circulating-liquid cooling circuit5, which guides the circulating liquid in the tank unit2to the heat exchanger4and returns the circulating liquid cooled by exchanging heat with the coolant of the coolant supply circuit6in the heat exchanger4into the tank unit2to regulate the temperature of the circulating liquid discharged from the circulating-liquid ejection circuit3to the load, are formed independently from each other, with the tank unit2as the center.

More specifically, the tank unit2includes a main tank20defined by a bottom, sides, and a top, in which circulating liquid with a predetermined depth is stored, and a sub-tank25defined by a bottom, sides, and a top likewise and having a larger capacity than the am tank20, in which the whole of the main tank20is housed and reserve circulating liquid is stored.

In the main tank20, a first partition wall21alower than the surface of the circulating liquid stored to a predetermined depth is provided vertically erected from the bottom of the tank20, and a second partition wall21blower than the height of the side from the bottom of the tank20is provided downward from the top of the tank20. Thus, the interior of the main tank20is partitioned into three chambers of a first chamber20aseparated by one side of the main tank20and the first partition wall21a, a second chamber20bseparated by the first partition wall21aand the second partition wall21b, and a third chamber20cseparated by the second partition wall21band another side.

In the main tank20, the first chamber20aand the second chamber20bcommunicate with each other through a void formed between the upper end of the first partition wall21aand the top of the tank20, and the second chamber20band the third chamber20ccommunicate with each other through a void formed between the lower end of the second partition wall21band the bottom of the tank20. Part of the upper end of the main tank20communicates with the sub-tank25so that the circulating liquid exceeding the maximum capacity of the main tank20can be discharged into the sub-tank25. The lower end of the first partition wall21ahas a communicating opening (not illustrated) so that the circulating liquid in the main tank20can be discharged to the outside via a drain cock53athrough a cooling circulation reverse path51connected to the bottom of the main tank20.

In the first chamber20aof the main tank20, a heater22athat heats the circulating liquid under the control of the control unit7is provided in the range from the vicinity of the upper end of the first partition wall21ato the vicinity of the bottom of the tank20. In the chamber20a, a thermostat22belectrically connected to the control unit7is provided in the range from the upper end of the first partition wall21ato the surface of the circulating liquid when a maximum volume of circulating liquid is stored in the tank20(that is, the highest surface of the circulating liquid). This allows the heater22ato be turned off, for example, when the temperature of the circulating liquid exceeds a predetermined temperature. Furthermore, in the chamber20a, a temperature fuse22c, which is electrically connected to the control unit7likewise, is provided between the highest surface of the circulating liquid and the top of the tank20. This allows, for example, when the temperature of the air (air temperature) in the tank20becomes higher than a predetermined temperature, determining that the circulating liquid is in an overheated state and turning off the power source of the temperature control apparatus1.

The second chamber20bof the main tank20is provided with an immersion cooling pump23athat pumps the circulating liquid on the bottom to the circulating-liquid cooling circuit5. Furthermore, the third chamber20cof the tank20is provided with an immersion circulation pump24athat pumps the circulating liquid on the bottom to the circulating-liquid ejection circuit3. These pumps are also controlled by the control unit7. The present embodiment uses inverter controlled pumps as the cooling pump23aand the circulation pump24a. Furthermore, the third chamber20cis provided with two upper and lower level switches24band24cat portions higher than the depthwise center. These switches are also electrically connected to the control unit7. By detecting the level (surface) of the circulating liquid in the main tank20using these switches24band24c, the operating status of an inner pump26and so on, described later, s controlled.

The sub-tank25houses the immersion inner pump26that pumps the circulating liquid on the bottom thereof into the main tank20and three level switches27a,27b, and27c, one above the depthwise center of the tank unit25and two at lower part. These switches are also electrically connected to the control unit7. The sub-tank25has, on its outer periphery, a level gauge28with which the amount of circulating liquid in the tank unit25can be visually checked from the outside of the casing10and a circulating-liquid inlet25afor supplying circulating liquid into the sub-tank25from the outside of the casing10. Furthermore, a drain pipe29is connected to the sub-tank25, and the end of the drain pipe29is let out from the casing10. The drain pipe29has a drain cock29aat the end. The circulating liquid in the sub-tank25can be discharged to the outside by opening the drain cock29a. By detecting the level (surface) of the circulating liquid in the sub-tank25with the three level switches27a,27b, and27c, for example, the liquid level can be decreased by opening the drain cock29a, or circulating liquid can be supplied to the sub-tank25through the circulating-liquid inlet25a.

The circulating-liquid ejection circuit3includes a discharge channel30connecting the third chamber20cof the main tank20in the tank unit2and the circulating-liquid ejection port11open to the outside of the casing10to discharge the circulating liquid to the load and a return channel31connecting the circulating-liquid return port12open to the outside of the casing10to receive the circulating liquid returned from the load and the main tank20of the tank unit2. The circulating liquid in the main tank20is discharged to the load through the discharge channel30and the circulating-liquid ejection port11by the circulation pump24aprovided in the third chamber20cof the main tank20, and the circulating liquid that has controlled the temperature of the load is returned to the main tank20through the circulating-liquid return port12and the return channel31.

In this case, the return channel31is preferably connected to the first chamber20awhich is positioned on the uppermost stream side in the main tank20and in which the heater22ais disposed, as illustrated inFIG.1. This allows, even if the temperature of the circulating liquid returned to the main tank20through the return channel31changes, the circulating liquid returned to the first chamber20ato be discharged to the discharge channel30after being regulated in temperature by the heater22aand the circulating-liquid cooling circuit5. This allows the circulating liquid regulated to a more accurate temperature to be supplied to the load.

The discharge channel30is provided with a first pressure sensor32and a first temperature sensor (a discharge-side temperature sensor)33, and the return channel31is provided with a second pressure sensor34and a second temperature sensor35. The discharge channel30and the return channel31are always connected by a bypass channel37. This allows, even if the flow of the circulating liquid is stopped at the load connected to the temperature control apparatus1, the circulating liquid to be returned to the main tank20through the bypass channel37, thereby maintaining the circulating state. The pressure sensors32and34and the temperature sensors33and35are electrically connected to the control unit7. This allows, for example, the heater, the cooling pump, and the circulation pump, to be appropriately controlled on the basis of the measured values from these sensors.

The circulating-liquid cooling circuit5includes a cooling circulation forward path50connecting the second chamber20bof the main tank20in the tank unit2and a circulating-liquid inlet42a(FIG.2) of the heat exchanger4and a cooling circulation reverse path51connecting a circulating-liquid outlet43a(FIG.2) of the heat exchanger4and the main tank20in the tank unit2. The circulating liquid in the main tank20is let flow into the heat exchanger4through the cooling circulation forward path50by the cooling pump23aprovided in the second chamber20bof the main tank20. The circulating liquid cooled by the heat exchanger4and flowing out of the heat exchanger4is returned to the main tank20through the cooling circulation reverse path51.

In this case, the cooling circulation reverse path51is also preferably connected to the first chamber20awhich is positioned on the uppermost stream side in the main tank20and in which the heater22ais disposed, like the return channel31, as illustrated inFIG.1. This allows the circulating liquid returned to the main tank20through the cooling circulation reverse path51to be discharged from the most downstream first chamber to the discharge channel30after being regulated in temperature together with the circulating liquid returned from the return channel31. This allows the circulating liquid regulated to a more accurate temperature to be supplied to the load.

A drain pipe52for the circulating-liquid cooling circuit5is connected to the cooling circulation forward path50, and the end thereof is let out of the casing10. The drain pipe52has a drain cock52aat the end. The circulating liquid in the circulating-liquid cooling circuit5can be discharged to the outside by opening the drain cock52a. A drain pipe53for the main tank20is connected to the cooling circulation reverse path51, and the end thereof is let out of the casing10. The drain pipe53also has a drain cock53aat the end. The circulating liquid in the main tank20can be discharged to the outside by opening the drain cock53a. The cooling circulation reverse path51is provided with a third temperature sensor54. The temperature sensor54is also electrically connected to the control unit7. This allows, for example, the rotational speed of the cooling pump23ato be controlled by the control unit7according to the temperature of the circulating liquid from the third temperature sensor54.

The coolant supply circuit6includes a coolant supply path60connecting the coolant supply port13which is open to the outside of the casing10to receive a coolant and a coolant inlet48(FIG.2) of the heat exchanger4and a coolant discharge path61connecting a coolant outlet49(FIG.2) of the heat exchanger4and the coolant discharge port14which is open to the outside of the casing10to discharge the coolant. This allows the coolant supplied through the coolant supply port13to be introduced into the heat exchanger4through the coolant supply path GO and the coolant that has cooled the circulating liquid in the heat exchanger4and is discharged from the heat exchanger4to be discharged to the outside from the coolant discharge port14through the coolant discharge path61.

The coolant supply path60is provided with a fourth temperature sensor62and a flowmeter63. The temperature sensor62and the flowmeter63are also electrically connected to the control unit7. This allows detecting abnormalities, for example, in the temperature or the flow rate of the coolant supplied to the heat exchanger4, and giving an alarm or the like.

In the present embodiment, a pressure regulation unit64for regulating the pressure of the coolant is connected to the coolant supply path60. Thus, even if the coolant is expanded by boiling or the like as a result of heat exchange with the high-temperature circulating liquid in the heat exchanger4, a problem, such as breakage, in the channel can be prevented by adjusting the pressure of the coolant with the pressure regulation unit64. The pressure regulation unit64may be disposed in the coolant discharge path61.

The coolant discharge path61is also provided with a fifth temperature sensor69that is electrically connected to the control unit7. This allows the temperature of the coolant discharged from the heat exchanger4to be, for example, displayed on control unit7by the control unit7.

This pressure regulation unit64includes, specifically, an accumulator main body65for adjusting the pressure, an on-off valve66(a two-way valve) disposed between the accumulator main body65and the coolant supply path60, a pressure gauge67disposed between the accumulator main body65and the on-off valve66, and a pressure relief valve (a two-way valve)68. The on-off valve66is always open at least during the operation of the temperature control apparatus1, and the pressure of the coolant can be monitored by the pressure gauge67. The pressure relief valve68is always closed during the operation of the temperature control apparatus1. For example, at the maintenance of the temperature control apparatus1, the pressure in the accumulator main body65can be released to the atmosphere by opening the pressure relief valve68, with the on-off valve66closed. The on-off valve66and the pressure relief valve68may be manually opened and closed as in the present embodiment or may be electrically connected to the control unit7so that the opening and closing can be controlled by the control unit7.

As illustrated inFIG.2, the heat exchanger4is entirely made of a metal material, such as stainless steel, extends along the longitudinal axis L, and includes a first heat exchange channel40through which the circulating liquid of the circulating-liquid cooling circuit5flows and a second heat exchange channel45through which the coolant for cooling the circulating liquid in the first heat exchange channel40flows.

The first heat exchange channel40is integrally, seamlessly formed of a helical channel portion41forming a helical shape around the axis L and extending in the axis L, an inflow channel portion42connected to one end of the helical channel portion41in the direction of the axis L and extending linearly along the axis L, and an outflow channel portion43connected to the other opposite end and extending linearly along the axis L by bending one metal pipe.

The first heat exchange channel40has a circulating-liquid inlet42afor introducing the circulating liquid into the heat exchanger4and a circulating-liquid outlet43afor discharging the circulating liquid cooled by heat exchange from the heat exchanger4at the opposite ends of the inflow channel portion42and the outflow channel portion43from the ends connected to the helical channel portion41(that is, the opposite ends of the first heat exchange channel40in the direction of axis L), respectively.

In contrast, the second heat exchange channel45is a channel space formed in a hollow metal shell44. The helical channel portion41of the first heat exchange channel40is housed in the second heat exchange channel45. The shell44is formed integrally with a hollow, cylindrical side wall44aextending in the direction of axis L, a hollow domical first end wall44bthat blocks one end of the cylindrical side wall44ain the direction of axis L, and a hollow domical second end wall44cthat blocks the other end likewise. In other words, the axis of the first heat exchange channel40is aligned with the axis of the cylindrical side wall44aof the shell44.

The first end wall44band the second end wall44cof the shell44have a first mounting opening46and a second mounting opening47for fixing the inflow channel portion42and the outflow channel portion43of the first heat exchange channel40to the shell44, respectively, with the inflow channel portion42and the outflow channel portion43let out from the second heat exchange channel45to the outside of the shell44. In this case, the inflow channel portion42and the outflow channel portion43are integrally formed of a metal pipe. The shell44further includes a coolant inlet48for introducing coolant into the second heat exchange channel45and a coolant outlet49for discharging the coolant after heat exchange with the circulating liquid in the first heat exchange channel40through the second heat exchange channel45. The coolant supply path60and the coolant discharge path61communicate with the second heat exchange channel45via the coolant inlet48and the coolant outlet49, respectively.

In the present embodiment, the coolant inlet48is open in the direction perpendicular to the axis L at one end of the shell44in the direction of axis L at which the outflow channel portion43of the first heat exchange channel40is disposed (specifically, an end of the cylindrical side wall44aadjacent to the second end wall44c). In contrast, the coolant outlet49is open in the direction of axis L at the other end of the shell44in the direction of axis L at which the inflow channel portion42of the first heat exchange channel40is disposed (specifically, the center of the first end wall44b).

One end of the metal pipe forming the cooling circulation forward path50is connected to the circulating-liquid inlet42aof the inflow channel portion42with connecting means, such as welding, and the other end of the metal pipe forming the cooling circulation reverse path51is connected to the circulating-liquid outlet of the outflow channel portion43with connecting means, such as welding. On the other hand, ends of the pipes forming the coolant supply path60and the coolant discharge path61are connected to the coolant inlet48and the coolant outlet49, respectively, using connecting means, such as joints or screwing.

The inside diameters of the first and second mounting openings46and47are formed larger than the outside diameters of the inflow channel portion42and the outflow channel portion43of the first heat exchange channel40. Hollow cylindrical members70and70made of a metal material, such as stainless steel, are fit and fixed on the outer peripheries of the inflow channel portion42and the outflow channel portion43in a liquidtight manner. The outer peripheries of the cylindrical members70and70are welded W and W to the shell44, with the cylindrical members70and70inserted into the first and second mounting openings46and47, respectively. In other words, the channel portions42and43are fixed to the shell44, with the cylindrical members70and70interposed therebetween.

Thus the use of a device in which the helical channel portion41of the first heat exchange channel40is housed in the second heat exchange channel (channel space)45formed in the hollow shell44as the heat exchanger4can simplify the structure of the heat exchanger4, thereby minimizing the welded portion. Moreover, the metal pipe forming the first heat exchange channel through which the high-temperature circulating liquid flows is not directly welded to the shell44forming the second heat exchange channel through which the low-temperature coolant flows. This prevents, even in cooling the high-temperature circulating liquid, the occurrence of problems, such as cracks, at the welded portions of the heat exchanger4due to the temperature difference between the circulating liquid and the coolant as much as possible. As a result, the durability of the temperature control apparatus1against the use of the high-temperature circulating liquid can be enhanced.

Next, the cylindrical member70will be specifically described with reference toFIG.3. The cylindrical member70includes a hollow, metal cylindrical body71whose opposite ends are open and a metal sealing member72that seals the gap between the outer periphery of the metal pipe forming the inflow channel portion42and the outflow channel portion43and the inner peripheral surface of the body71in a liquidtight manner and that fixes the body71to the channel portions42and43. The outer periphery of the body is circularly and continuously welded W and W to the shell44at the first and second mounting openings46and47in a state in which part of the body71fixed to the channel portions42and43is inserted into the shell44through the openings46and47from the outside of the shell44.

The body71is formed by combining a fixing cylindrical portion73fixed to the shell44by the weld W and a sealing cylindrical portion74having the sealing member72around the inner periphery together. The fixing cylindrical portion73integrally has an external thread75at an end disposed outside the shell44. An inclined surface76whose inside diameter increases linearly toward the end of the external thread75is formed around the inner periphery of the end of the external thread75. The sealing cylindrical portion74has an internal thread77around the inner periphery of an end adjacent to the fixing cylindrical portion73. The sealing cylindrical portion74has, at a portion of the inner periphery deeper than the internal thread77, a shoulder78whose inside diameter increases stepwise toward the internal thread77.

Furthermore, the ring-shaped sealing member72has, in cross-section, a wedge shape with an acute angle at an end edge oriented to the fixing cylindrical portion73. The sealing member72is attached to the shoulder78of the sealing cylindrical portion74, with the ring-shaped end edge inclined to the central axis L1. This causes, when the cylindrical portions73and74are fastened by screwing the internal thread77of the sealing cylindrical portion74onto the external thread75of the fixing cylindrical portion73, the sealing member72to be pushed toward the end edge by the shoulder78of the sealing cylindrical portion74. This causes the end edge of the sealing member72to be brought into pressure-contact with the outer periphery of each of the channel portions42and43into a bitten state. As a result, the gap between each of the channel portions42and43and the body71of the cylindrical member70is sealed in a liquidtight manner, and the body71is fixed to each of the channel portions42and43.

In the present embodiment, the sealing member72includes two ring-shaped first and second wedge-shaped sealing pieces72aand72b. The wedge-shaped sealing pieces72aand72bare attached to the individual steps of the two-step shoulder78of the sealing cylindrical portion74, as illustrated inFIG.3.

At that time, the end of the first sealing piece72aincluding the end edge enters between the inclined surface76of the external thread75and each of the outer peripheries of the inflow channel portion42and the outflow channel portion43. This causes the end of the first sealing piece72ato be brought into pressure-contact with the inclined surface76and the end edge of the sealing piece72ato be brought into pressure-contact with the outer periphery of each of the channel portions42and43in a bitten state.

The second sealing piece72bis disposed at a rear end of the first sealing piece72aopposite to the end edge. An end of the second sealing piece72bincluding the end edge enters between the rear end of the first sealing piece72aand the outer periphery of each of the channel portions42and43. This causes the rear end of the first sealing piece72ato expand and the end edge of the second sealing piece72bto be brought into pressure-contact with the outer periphery of each of the channel portions42and43. An example substitute for the cylindrical member70is a bite joint including two ring-shaped ferrules serving as the wedge-shaped sealing pieces72aand72b.

As illustrated inFIG.1, the control unit7includes a temperature setting unit7afor appropriately setting the temperature of the circulating liquid to be discharged to the load through the discharge channel30. A method for controlling the cooling pump23aand the circulation pump24aaccording the set temperature of the circulating liquid using the control unit7will be described hereinbelow with reference to the graph inFIG.4. In the present embodiment, a predetermined threshold temperature (75° C.) is set in the control unit7for the temperature of the circulating liquid to be delivered to the load. The fact that the delivery temperature of the circulating liquid is higher than the threshold temperature indicates that the temperature control apparatus1is in operation. The fact that the delivery temperature is lower than or equal to the threshold temperature indicates that the temperature control apparatus1is at idle (at rest).

First, in the first step, in a state in which the set temperature of the circulating liquid is set to a temperature (40° C.) lower than the threshold temperature (75° C.), and the delivery temperature of the circulating liquid (hereinafter referred to as “measured temperature”) measured by the first temperature sensor33of the discharge channel30is also decreased to the set temperature, in other words, the temperature control apparatus1is at idle, the inverter-controlled cooling pump and circulation pump are maintained at a predetermined low rotational speed (low frequency) by the control unit7.

In the second step, upon setting the set temperature of the circulating liquid to a temperature higher than the threshold temperature, the rotational speed of the circulation pump24ais switched to a high rotational speed (high frequency), and the high rotational speed is maintained.

For the cooling pump23a, the rotational speed is further decreased once and is thereafter gradually increased at a predetermined timing before the temperature of the circulating liquid measured by the temperature sensor33reaches the set temperature. Thereafter, the increase in the rotational speed is stopped at the point in time the measured temperature reaches the set temperature, so that the measured temperature and the set temperature are equalized. In this state, the rotational speed (lower than that in the first step) is maintained.

Subsequently, in the third step, when the set temperature of the circulating liquid is further increased, the rotational speed of the circulation pump24ais maintained at the predetermined rotational speed following the second step.

For the cooling pump23a, the rotational speed is decreased to the same rotational speed as that in the second step once concurrently therewith and is then gradually increased again at a predetermined timing before the measured temperature of the circulating liquid reaches the set temperature. At that time, the gradient of the change in rotational speed is smaller than that in the second step. Thereafter, the increase in rotational speed is stopped at the point in time the measured temperature of the circulating liquid reaches the set temperature, so that the measured temperature and the set temperature are equalized. In this state, the rotational speed (lower than that in the first step and the second step) is maintained, as in the second step.

Next in the fourth step, when the set temperature of the circulating liquid is decreased to the set temperature of the second step, the rotational speed of the circulation pump24ais maintained at the predetermined high rotational speed following the third step.

For the cooling pump23a, the rotational speed is increased to a rotational speed higher than the idling rotational speed of the first step once concurrently therewith and is then gradually decreased at a predetermined timing before the measured temperature of the circulating liquid reaches the set temperature. Thereafter, the decrease in the rotational speed is stopped at the point in time the measured temperature of the circulating liquid reaches the set temperature, so that the measured temperature and the set temperature are equalized. In this state, the rotational speed (the same rotational speed as that in the second step) is maintained.

Subsequently, in the fifth step, when the set temperature of the circulating liquid is further decreased to the set temperature (40° C.) of the first step, the rotational speed of the circulation pump24ais switched to the same predetermined low rotational speed as that in the first step, and the low rotational speed is maintained.

For the cooling pump23a, the rotational speed is increased to the same rotational speed as that in the fourth step once concurrently therewith and is thereafter gradually decreased again at a predetermined timing before the measured temperature of the circulating liquid reaches the set temperature. At that time, the gradient of the change in rotational speed is smaller than that in the fourth step. Thereafter, the decrease in the rotational speed is stopped at the point in time the measured temperature of the circulating liquid reaches the set temperature, so that the measured temperature and the set temperature are equalized to each other. In that state, the rotational speed (the same rotational speed as that in the first step) is maintained.

In other words, in the present embodiment, when the temperature of the circulating liquid set by the temperature setting unit7ais lower than a predetermined threshold temperature, the rotational speed of the circulation pump24ais maintained at a low rotational speed, and when it is higher than the predetermined threshold temperature, the rotational speed of the circulation pump24ais maintained at a high rotational speed.

When the set temperature is increased by the temperature setting unit7a, the rotational speed of the cooling pump23ais decreased once and is thereafter gradually increased. When the set temperature is decreased, the rotational speed of the cooling pump23ais increased once and is thereafter gradually decreased. When the temperature of the circulating liquid measured by the first temperature sensor33in the discharge channel30(that is, the measured temperature of the circulating liquid) becomes equal to the set temperature, the rotational speed at that time is maintained.

In increasing the set temperature, the higher the set temperature, the smaller the gradient of the change in the rotational speed when the rotational speed of the cooling pump23ais decreased once and is thereafter gradually increase is set. In decreasing the set temperature, the lower the set temperature, the smaller the gradient of the change in the rotational speed when the rotational speed is increased once and is thereafter gradually decreased is set.

Thus, in the present embodiment, the circulation pump24ais immersed in the circulating liquid in the main tank20, and when the set temperature of the circulating liquid is higher than a predetermined threshold temperature, the rotational speed of the circulation pump24ais maintained at a high rotational speed. This allows the temperature of the circulating liquid to be efficiently increased to a set temperature and to be maintained at the temperature using the heat generated in the circulation pump24ain addition to the heater22a.

Furthermore, when the set temperature of the circulating liquid is set from the temperature higher than the threshold temperature to a lower temperature, the rotational speed of the circulation pump24ais decreased to a lower rotational speed and is maintained at the lower rotational speed, and at the same time, the rotational speed of the cooling pump23aincreases. This allows suppressing the heat generation of the circulation pump24aand accelerating the cooling of the circulating liquid with the heat exchanger4, thereby efficiently decreasing the temperature of the circulating liquid to the set temperature.

REFERENCE SIGNS LIST