JP2005207661A - Extremely low temperature refrigerating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an extremely low temperature refrigerating device with a defrosting circuit, wherein a defrosting operation time is shortened by preventing lubricating oil passing through a cooler from being coagulated again in a heat exchanger. <P>SOLUTION: The downstream end of the defrosting circuit 60 is parted into a main branch circuit 60a and a sub branch circuit 60b. The downstream end of the main branch circuit 60a is connected at the inlet side of cryo-coil 52 to a main refrigerant pipe 2a ranging to a sixth capillary tube 53. The downstream end of the sub branch circuit 60b is connected at the outlet side of the cryo-coil 52 to a refrigerant pipe ranging to the secondary side of a fourth heat exchanger 43. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ultra-low temperature refrigeration apparatus for generating an ultra-low temperature level of cold, particularly a compressor lubricating oil and a high melting point (for example, around −100 ° C.) high-boiling refrigerant (hereinafter referred to as “lubricating oil etc.”). ) Related to measures for suppressing coagulation.

  Conventionally, for example, as disclosed in Patent Document 1, a mixed refrigerant composed of several kinds of refrigerants having different boiling point temperatures is sequentially condensed from a refrigerant having a high boiling point temperature to a refrigerant having a low boiling point temperature. A so-called mixed refrigerant type ultra-low temperature refrigeration apparatus is known in which a refrigerant having an evaporating temperature is finally evaporated to obtain a desired ultra-low temperature. This type of ultra-low temperature refrigeration apparatus is installed, for example, in a vacuum chamber of a vacuum film forming apparatus used for manufacturing wafers and the like, and is used for freezing the gas in the vacuum chamber to raise the vacuum level.

  In such an ultra-low temperature refrigeration apparatus, the mixed refrigerant flows through a refrigerant circuit including a compressor, a condenser, a multi-stage gas-liquid separator and a cascade heat exchanger, and a cooler (evaporator). It has become. And after condensing mainly high boiling point refrigerant in the condenser, it is separated into liquid refrigerant and gas refrigerant in the first stage gas-liquid separator, and on the primary side of the first stage cascade heat exchanger, The gas refrigerant and the liquid refrigerant decompressed after being separated are heat-exchanged and cooled. In the second and subsequent cascade heat exchangers, heat exchange is performed in the same manner, and the liquid refrigerant flowing out from the primary side of the final stage cascade heat exchanger is decompressed to evaporate the low boiling point refrigerant in the cooler. In this way, a very low temperature level of cold is supplied. Further, the refrigerant cooled by this cooler is returned to the secondary side of the final stage cascade heat exchanger and returned to the compressor while passing through the secondary side of the cascade heat exchanger of each stage. Yes.

In addition, the discharge side of the compressor and the inlet side of the cooler are connected to the ultra-low temperature refrigeration apparatus by a defrost circuit, and the normal operation of the refrigeration apparatus is stopped when film formation is not performed by the vacuum film formation apparatus. In the defrosting operation, the discharge gas of the compressor is supplied to the cooler to defrost the cooler.
JP-A-6-347112

  However, in that case, when starting the defrost operation, when lubricating oil or the like mixed in the refrigerant mixture flows through the defrost circuit to prevent seizure of the sliding contact portion or the like in the compressor, the lubricating oil or the like It is supplied to a cooler still at an ultra-low temperature level and solidifies in the cooler. After that, even if the lubricating oil or the like passes through the cooler due to the temperature rise of the cooler, the lubricating oil or the like coming out of this cooler is supplied to the heat exchanger that is also at an ultra-low temperature level. Even in the exchanger, the lubricating oil or the like is solidified, and it takes time for the solidification of the lubricating oil or the like to be eliminated, resulting in a problem that the defrosting operation time becomes long.

  The present invention has been made in view of the above points, and the object of the present invention is to improve the structure of the defrost circuit in the ultra-low temperature refrigeration apparatus provided with the defrost circuit as described above, and in particular, The purpose is to shorten the defrosting operation time by suppressing the solidification of the lubricating oil or the like in the exchanger.

  In the present invention, the downstream end portion of the defrost circuit is branched into two to increase the temperature of the cooler and the heat exchanger at the same time.

That is, the invention of claim 1 is a compressor that compresses a mixed refrigerant obtained by mixing a plurality of types of refrigerants having different boiling points,
A condenser that cools and liquefies a high boiling point refrigerant among the mixed refrigerant discharged from the compressor;
A multi-stage gas-liquid separator that sequentially separates the mixed refrigerant liquefied by the condenser from a high boiling point refrigerant into a low boiling point refrigerant into a liquid refrigerant and a gas refrigerant;
A plurality of stages in which the primary-side gas refrigerant separated by each gas-liquid separator is cooled by heat exchange with the secondary-side liquid refrigerant separated and decompressed by each gas-liquid separator. A cascade heat exchanger,
A refrigerant circuit that is connected to a cooler that evaporates the low-boiling-point refrigerant that has flowed out from the cascade heat exchanger at the final stage of the plurality of stages and cools the object to be cooled to an ultra-low temperature level, and
In the ultra-low temperature refrigeration apparatus including a defrost circuit that supplies the mixed refrigerant discharged from the compressor to the cooler at the time of defrosting the cooler,
The downstream end of the defrost circuit branches into a main branch circuit and a sub branch circuit,
The downstream end of the main branch circuit is connected to the refrigerant circuit on the inlet side of the cooler, while the downstream end of the sub branch circuit is connected to the refrigerant circuit on the outlet side of the cooler. .

  Therefore, according to the present invention, the downstream end of the defrost circuit branches into a main branch circuit and a sub branch circuit, and the downstream end of the main branch circuit is connected to the refrigerant circuit on the inlet side of the cooler, Since the downstream end of the circuit is connected to the refrigerant circuit on the outlet side of the cooler, the refrigerant flowing through the main branch circuit is supplied to the cooler, and the refrigerant flowing through the sub-branch circuit is supplied to the cooler. It can supply to the heat exchanger connected to the refrigerant circuit of the exit side, and can heat-up this heat exchanger simultaneously, respectively. Thereby, it can suppress that the lubricating oil etc. which passed the said cooler solidify again within a heat exchanger. By suppressing the blockage of the refrigerant circuit due to the solidification of the lubricating oil or the like, good circulation of the mixed refrigerant in the refrigerant circuit can be ensured, and the defrosting operation time can be shortened.

The invention of claim 2 is the ultra-low temperature refrigeration apparatus according to claim 1,
The sub-branch circuit is provided with an opening / closing valve.

  Therefore, according to the present invention, the temperature of the cooler and the heat exchanger are simultaneously raised as described above by opening the on-off valve, and the temperature is raised above the pour point at which the lubricating oil and the like can smoothly flow in the heat exchanger. After that, by closing the on-off valve, the refrigerant that has been branched into the main branch circuit and the sub-branch circuit can be circulated only to the main branch circuit to raise the temperature of the cooler. The operation time can be further shortened.

  As described above, according to the invention according to claim 1, the downstream end portion of the defrost circuit in the ultra-low temperature refrigeration apparatus is branched into the main branch circuit and the sub branch circuit, and these are respectively connected to the inlet side and the outlet side of the cooler. Since it is connected to the refrigerant circuit, the temperature of the cooler and the heat exchanger can be raised at the same time, and it is possible to prevent the lubricating oil etc. that has passed through the cooler from solidifying in the heat exchanger, thus ensuring good circulation of the refrigerant. The defrosting operation time can be shortened.

  According to the second aspect of the invention, since the on / off valve is provided in the sub branch circuit, the main branch is made by closing the on / off valve after the temperature is raised above the pour point where lubricating oil or the like can flow smoothly in the heat exchanger. The refrigerant can be circulated only in the circuit to raise the temperature of the cooler, and the defrosting operation time can be further shortened.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or its application.

<Embodiment 1>
FIG. 1 shows an example of a layout of a vacuum film-forming apparatus A according to an embodiment of the present invention. Reference numeral 120 denotes a vacuum chamber in which a wafer (not shown) is formed by keeping the inside in a vacuum state. A loading / unloading port (not shown) opened and closed by an opening / closing door 123 is opened at 120, and a wafer to be deposited is loaded into the vacuum chamber 120 or deposited with the opening / closing door 123 opened. The subsequent wafer is unloaded from the vacuum chamber 120. A vacuum pump 121 is connected to the vacuum chamber 120 via a communication passage 122, and a gate valve 124 is provided at a connection portion of the communication passage 122 with the vacuum chamber 120 to switch between the two to open or close. The vacuum chamber 120 is evacuated by the operation of the vacuum pump 121 with the open / close door 123 closed and the gate valve 124 opened.

  The vacuum film forming apparatus A is provided with an ultra-low temperature refrigeration apparatus 10 constituting the refrigeration system of the present invention, and a vacuum coil 121 of the vacuum pump 121 is evacuated by a cryocoil (cooler) 52 described later of the ultra-low temperature refrigeration apparatus 10. In this state, the gas and moisture to be cooled in the vacuum chamber 120 are directly cooled to an ultra-low temperature level so that the gas and the like are captured and the vacuum level in the vacuum chamber 120 is raised.

  On the other hand, FIG. 2 shows another example of the layout of the vacuum film-forming apparatus A. The cryocoil 52 of the refrigeration apparatus 10 is disposed not in the vacuum chamber 120 but in the middle of the communication path 122 and is formed by the vacuum pump 121. The vacuum level in the vacuum chamber 120 is increased by cooling and capturing the gas and moisture in the communication path 122, that is, indirectly the gas and moisture in the vacuum chamber 120 by the ultra-low temperature refrigeration apparatus 10 in a vacuum state. I have to. The other structure is the same as that of the vacuum film forming apparatus A shown in FIG.

  The ultra-low temperature refrigeration apparatus 10 generates refrigeration at an ultra-low temperature level of −100 ° C. or lower by using a non-azeotropic refrigerant mixture obtained by mixing five or six refrigerants having different boiling temperatures as refrigerants.

  FIG. 3 shows the overall configuration of the ultra-low temperature refrigeration apparatus 10. Reference numeral 1 denotes a closed cycle refrigerant circuit in which the mixed refrigerant is enclosed. The refrigerant circuit 1 is formed by connecting various devices described below through refrigerant piping. A compressor 20 compresses the gas refrigerant, and a first oil separator 15 is connected to a discharge portion of the compressor 20. The first oil separator 15 separates compressor lubricating oil or the like mixed in the gas refrigerant discharged from the compressor 20 from the gas refrigerant, and the separated lubricating oil or the like is oil. It is returned to the suction side of the compressor 20 through the return pipe 18. A water-cooled condenser 21 is connected to the refrigerant discharge portion of the first oil separator 15 to cool and condense the gas refrigerant discharged from the compressor 20 by heat exchange with the cooling water in the cooling water passage 11. The discharge side of the water-cooled condenser 21 is connected to the primary side of the auxiliary condenser 22 via a dryer 17 that removes moisture and contamination in the refrigerant. In the auxiliary condenser 22, the gas refrigerant from the water-cooled condenser 21 is supplied. It cools and condenses by exchanging heat with the low-temperature secondary reflux refrigerant sucked into the compressor 20. In this embodiment, the water-cooled condenser 21 and the auxiliary condenser 22 constitute a condenser, and both the condensers 21 and 22 condense and liquefy the gas refrigerant having the highest boiling point temperature among the mixed refrigerants. It has become.

  A first gas-liquid separator 24 is connected to a primary-side discharge portion of the auxiliary capacitor 22, and the gas-liquid mixed refrigerant from the auxiliary capacitor 22 is converted into a liquid refrigerant and a gas by the first gas-liquid separator 24. Separated into refrigerant. The primary side of the cascade-type first heat exchanger 25 is provided in the gas refrigerant discharge portion of the first gas-liquid separator 24, and the same is provided in the liquid refrigerant discharge portion via the first capillary tube 26 as decompression means. The secondary side of the first heat exchanger 25 is connected to each other, and after the liquid refrigerant separated by the first gas-liquid separator 24 is decompressed by the first capillary tube 26, the secondary side of the first heat exchanger 25 is The gas refrigerant on the primary side is cooled by this evaporation, and the gas refrigerant having the second highest boiling point temperature in the mixed refrigerant is condensed and liquefied.

  Further, a second gas-liquid separator 30 is connected to the primary discharge section of the first heat exchanger 25, and the gas from the first heat exchanger 25 is connected to the second gas-liquid separator 30. The liquid mixed refrigerant is separated into a liquid refrigerant and a gas refrigerant. The gas refrigerant discharge part of the second gas-liquid separator 30 is the same as the primary side of the cascade-type second heat exchanger 31, and the liquid refrigerant discharge part is the same through a second capillary tube 32 as decompression means. The secondary side of the second heat exchanger 31 is connected to each other, and after the liquid refrigerant separated by the second gas-liquid separator 30 is decompressed by the second capillary tube 32, the secondary side of the second heat exchanger 31. The gas refrigerant on the primary side is cooled by this evaporation, and the gas refrigerant having the third highest boiling point temperature in the mixed refrigerant is condensed and liquefied.

  Further, in the same manner as in the connection structure, a third gas-liquid separator 36, a third heat exchanger 37, and a third capillary tube 38 are also provided at the primary discharge portion of the second heat exchanger 31. A fourth gas-liquid separator 42, a fourth heat exchanger 43, and a fourth capillary tube 44 are connected to the discharge section on the primary side in the third heat exchanger 37 (these connection structures are described above). Since it is the same as the connection structure of the first gas-liquid separator 24, the first heat exchanger 25, and the first capillary tube 26, detailed description thereof is omitted), and the liquid separated by the third gas-liquid separator 36 After the refrigerant is decompressed by the third capillary tube 38, the refrigerant is supplied to the secondary side of the third heat exchanger 37 and evaporated, and the gas refrigerant on the primary side is cooled by the evaporation. The fourth highest temperature gas refrigerant is condensed While being liquefied, the liquid refrigerant separated by the fourth gas-liquid separator 42 is decompressed by the fourth capillary tube 44 and then supplied to the secondary side of the fourth heat exchanger 43 to evaporate. The gas refrigerant on the side is cooled by heat exchange, and the gas refrigerant having the lowest boiling point temperature among the mixed refrigerants is condensed and liquefied.

  And the primary side of the subcooler (subcooler) 47 which consists of a heat exchanger is connected to the primary side discharge part in the said 4th heat exchanger 43, and the primary side discharge part of this subcooler 47 The refrigerant pipe connected to is branched into a main refrigerant pipe 2a and a sub refrigerant pipe 2b on the way.

  A fifth capillary tube 48 is connected in the middle of the auxiliary refrigerant pipe 2b. The downstream end of the sub refrigerant pipe 2b is connected to the secondary side of the same subcooler 47, and the secondary side of the subcooler 47 is connected to the secondary side of the fourth heat exchanger 43 via the refrigerant pipe. After the refrigerant discharged from the fourth heat exchanger 43 is connected to the primary side of the subcooler 47, a part of the refrigerant is decompressed by the fifth capillary tube 48 of the sub refrigerant pipe 2b, The liquid refrigerant is supplied to the secondary side of the subcooler 47 to evaporate, and the primary side gas refrigerant is cooled by the heat of evaporation.

  On the other hand, in the middle of the main refrigerant pipe 2a, a sixth capillary tube 53 and a cryocoil 52 are connected in series from the upstream side. The cryocoil 52 constitutes a main cooler. As shown in FIG. 1 or FIG. 2, the cryocoil 52 cools a gas or moisture as a cooling target in the vacuum chamber 120. The downstream end of the main refrigerant pipe 2 a is connected to the refrigerant pipe between the secondary side of the fourth heat exchanger 43 and the secondary side of the subcooler 47, and from the primary side of the subcooler 47. The remaining portion of the discharged refrigerant is decompressed by the sixth capillary tube 53 of the main refrigerant pipe 2a, and then supplied to the cryocoil 52 to evaporate. The evaporation heat causes gas and moisture (cooling target) in the vacuum chamber 120 to be − It cools to an ultra-low temperature level of 100 ° C. or lower, captures the gas and moisture, and increases the vacuum level.

  In addition, the secondary side (and the cryocoil 52) of the supercooler 47, the fourth heat exchanger 43, the third heat exchanger 37, the second heat exchanger 31, the first heat exchanger 25, and the auxiliary condenser 22 are used. Are connected in series in the order of description by refrigerant piping, and the secondary side of the auxiliary capacitor 22 is connected to the suction side of the compressor 20, and the refrigerant gasified by evaporation in the mixed refrigerant is compressed into the compressor. 20 is inhaled.

  The cryocoil 52 is arranged in the vacuum chamber 120 so that the gas in the vacuum chamber 120 is directly cooled by the cryocoil 52. However, instead of the cryocoil 52, a brine cooler is provided, The brine cooler is connected to the heat absorption part located in the vacuum chamber 120 by a brine circuit, and in this brine cooler, the brine in the brine circuit is cooled to an ultra-low temperature level, and the same temperature level is applied to the heat absorption part in the vacuum chamber 120 by the brine. You may make it provide the cold of.

  The condensers 21 and 22, the heat exchangers 25, 31, 37, and 43 and the supercooler 47 may be any of a double tube structure, a plate structure, and a shell and tube structure. Further, instead of the capillary tubes 26, 32, 38, 44, other decompression means such as an expansion valve can be used.

  Next, features of the present invention will be described. As shown in FIG. 3, a defrost circuit 60 is provided that supplies high-temperature gas refrigerant (hot gas) discharged from the compressor 20 to the cryocoil 52 and the fourth heat exchanger 43 as they are. The upstream end of the defrost circuit 60 is connected to a refrigerant pipe between the first oil separator 15 and the water-cooled condenser 21. The downstream end of the defrost circuit 60 branches into a main branch circuit 60 a and a sub branch circuit 60 b, and the downstream end of the main branch circuit 60 a is between the sixth capillary tube 53 on the inlet side of the cryocoil 52. The downstream end of the sub-branch circuit 60 b is connected to the refrigerant pipe between the outlet side of the cryocoil 52 and the secondary side of the fourth heat exchanger 43.

  In FIG. 3, 61 is an electromagnetic on-off valve connected to the defrost circuit 60 upstream of the branch portions of the main and sub branch circuits 60a and 60b, and 62 is a gap between the sixth capillary tube 53 and the cryocoil 52. It is an electromagnetic on-off valve connected to the upstream side (sixth capillary tube 53 side) with respect to the downstream end of the main branch circuit 60a in the main refrigerant pipe 2a.

  A second oil separator 16 for separating compressor lubricating oil and the like from the gas refrigerant is disposed between the upstream end of the defrost circuit 60 and the electromagnetic on-off valve 61. The lubricating oil or the like separated by the second oil separator 16 is returned to the suction side of the compressor 20 through the oil return pipe 18 in the same manner as the first oil separator 15.

  When the vacuum chamber 120 of the vacuum film forming apparatus A shown in FIG. 1 is in a vacuum state to perform film formation on a wafer, the defrost circuit 60 is closed by opening the electromagnetic opening / closing valve 61 and the electromagnetic opening / closing valve 62 is opened. By opening the main refrigerant pipe 2a, the cryocoil 52 evaporates the low boiling point refrigerant and cools and captures the gas and moisture in the vacuum chamber 120, while opening the open / close door 123 and forming the wafer in the vacuum chamber 120. At the time of defrosting in a state where no film is formed, the defrost circuit 60 is opened by opening the electromagnetic on-off valve 61 and the main refrigerant pipe 2 a is closed by closing the electromagnetic on-off valve 62, so that the high temperature discharged from the compressor 20 The gas refrigerant (hot gas) is supplied to the cryocoil 52 through the defrost circuit 60 as it is, and the trapping of moisture and the like in the cryocoil 52 is returned. Unishi to have.

  In FIG. 3, reference numeral 65 denotes a buffer tank for preventing an abnormal increase in the discharge pressure of the compressor 20 due to insufficiently condensed gas refrigerant at the start of operation of the cryogenic refrigeration apparatus 10. The vicinity of the electromagnetic on-off valve 61 of the defrost circuit 60, the vicinity of the electromagnetic on-off valve 62 between the sixth capillary tube 53 and the cryocoil 52, the outlet side of the cryocoil 52, and the secondary side of the fourth heat exchanger 43 The first to third manual on-off valves 71, 72, 73 are respectively disposed in the refrigerant pipes between the first and third manual open / close valves. These first to third manual on-off valves 71, 72, 73 are closed when the cryocoil 52 is replaced or maintained, so that the mixed refrigerant remaining in the piping does not leak to the outside. .

  Further, a refrigerant supply line 70 for supplying a mixed refrigerant into the refrigerant circuit 1 of the cryogenic refrigeration apparatus 10 is provided in the refrigerant pipe between the outlet side of the cryocoil 52 and the secondary side of the fourth heat exchanger 43. Is connected. The refrigerant supply pipe 70 also serves as a discharge pipe for discharging the mixed refrigerant from the refrigerant circuit 1. The refrigerant supply pipe 70 is provided with a supply opening / closing valve 75 that opens when the refrigerant is supplied or discharged.

  In the embodiment configured as described above, when a wafer is formed in the vacuum chamber 120 of the vacuum film forming apparatus A, the ultra-low temperature refrigeration apparatus 10 is operated and the inside of the vacuum chamber 120 (or the communication path 122). The water or the like is cooled and trapped to an ultralow temperature level of −100 ° C. or lower, and the vacuum chamber 120 is evacuated. That is, during operation of the cryogenic refrigeration apparatus 10, the defrost circuit 60 is closed by closing the electromagnetic on-off valve 61, and the main refrigerant pipe 2 a is opened by opening the electromagnetic on-off valve 62. As a result, the mixed refrigerant discharged from the compressor 20 is cooled by the water-cooled condenser 21 and then cooled by the secondary-side refrigerant returned to the compressor 20 by the auxiliary condenser 22, and the boiling point of the mixed refrigerant has the highest temperature. The gas refrigerant is condensed and liquefied. This refrigerant is separated into a gas refrigerant and a liquid refrigerant in the first gas-liquid separator 24, and the liquid refrigerant evaporates on the secondary side of the first heat exchanger 25 after being depressurized by the first capillary tube 26. The gas refrigerant from the first gas-liquid separator 24 is cooled by heat, and the gas refrigerant having the second highest boiling point temperature in the mixed refrigerant is condensed and liquefied. Thereafter, in the same manner, in the second to fourth heat exchangers 31, 37, 43, the gas refrigerant is condensed and liquefied in order from the highest boiling point temperature of the mixed refrigerant. The gas refrigerant having the lowest boiling point temperature is condensed and liquefied.

  The refrigerant discharged from the primary side of the fourth heat exchanger 43 is in a gas-liquid mixed state, and this gas-liquid mixed refrigerant passes through the primary side of the subcooler 47 and then passes through the main refrigerant pipe 2a and the sub refrigerant. It isolate | separates into the piping 2b. The refrigerant flowing into the sub refrigerant pipe 2b is decompressed by the fifth capillary tube 48 and then supplied to the secondary side of the subcooler 47 to evaporate. The evaporative heat causes supercooling from the fourth heat exchanger 43. The gas-liquid mixed refrigerant supplied to the primary side of the vessel 47 is further cooled.

  Further, the remaining refrigerant in the gas-liquid mixed state that flows into the main refrigerant pipe 2a after being discharged from the primary side of the subcooler 47 is decompressed by the sixth capillary tube 53, and after the decompression, it is evaporated by the cryocoil 52 to be evacuated. For example, chilling of −100 ° C. or lower is applied to the gas or moisture in the chamber 120. The chilling at a temperature of −100 ° C. or lower traps gas and moisture in the vacuum chamber 120 and raises the vacuum level in the vacuum chamber 120.

  On the other hand, during the defrost operation in which the wafer is not formed in the vacuum chamber 120 of the film forming apparatus A, the defrost circuit 60 is opened by opening the electromagnetic opening / closing valve 61 and the electromagnetic opening / closing valve 62 is closed. The refrigerant pipe 2a is closed, so that the high-temperature gas refrigerant discharged from the compressor 20 is supplied from the main branch circuit 60a of the defrost circuit 60 via the inlet side of the cryocoil 52, while being supplied from the sub branch circuit 60b. The heat is also supplied to the four heat exchangers 43, and release of moisture and the like in the cryocoil 52 and the fourth to second heat exchangers 43, 37, and 31 is simultaneously performed.

  That is, the downstream end of the defrost circuit 60 is branched into a main branch circuit 60a and a sub branch circuit 60b, and the downstream end of the main branch circuit 60a is connected to the refrigerant pipe on the inlet side of the cryocoil 52, Since the downstream end of 60b is connected to the refrigerant pipe on the outlet side of the cryocoil 52, the refrigerant flowing through the main branch circuit 60a is supplied to the cryocoil 52 and flows through the cryocoil 52 and also through the sub branch circuit 60b. The refrigerant is supplied to the fourth to second heat exchangers 43, 37, and 31 connected to the refrigerant pipe on the outlet side of the cryocoil 52, and the temperature of the fourth to second heat exchangers 43, 37, and 31 is simultaneously increased. be able to. As a result, the lubricating oil or the like that has passed through the cryocoil 52 that is still at an extremely low temperature at the start of the defrost operation is prevented from solidifying again in the fourth to second heat exchangers 43, 37, and 31. A good circulation can be ensured and the defrosting operation time can be shortened. As a result, the evacuation time in the vacuum chamber 120 and the film formation process time can be shortened and the efficiency can be improved.

  Next, when the inside of the vacuum chamber 120 is again evacuated after the defrost operation, the defrost circuit 60 is closed by closing the electromagnetic on-off valve 61 and the electromagnetic on-off valve 62 is opened in the same manner as described above. The main refrigerant pipe 2a is opened, and the low-boiling point refrigerant discharged from the primary side of the supercooler 47 evaporates in the cryocoil 52, thereby quickly cooling the inside of the vacuum chamber 120 from room temperature to an ultra-low temperature level.

  Note that the outlet side of the cryocoil 52 may be connected to the secondary side of the heat exchanger at a higher temperature than the secondary side of the fourth heat exchanger 43. Specifically, if the refrigerant pipe is connected so that a high-temperature gas refrigerant (hot gas) is supplied to a part having a temperature below the pour point (for example, −50 ° C.) at which the lubricating oil flows smoothly in the refrigerant pipe. Good.

  In the present embodiment, in the first to fourth heat exchangers 25, 31, 37, and 43, the refrigerant that flows toward the cryocoil 52 is returned to the primary side, and the refrigerant that recirculates from the cryocoil 52 to the compressor 20 is the secondary. In contrast to this, the refrigerant directed to the cryocoil 52 may be introduced to the secondary side, and the refrigerant returning from the cryocoil 52 to the compressor 20 may be introduced to the primary side. Of course. Moreover, it is good also as a structure which combined these separately.

  Moreover, although the system which performs gas-liquid separation 4 steps | paragraphs was shown in this embodiment, it replaces with this and this invention is applicable also to the system which performs gas-liquid separation 3 steps | paragraphs or 5 steps or more.

  In the present embodiment, the water cooling system using the water cooling condenser 21 is shown. However, instead of this, a system using an air cooling condenser may be used.

<Embodiment 2>
FIG. 4 is a refrigerant circuit of the cryogenic refrigeration apparatus 10 according to the second embodiment. Since the difference from the first embodiment is only the circuit configuration of the defrost circuit 60, the same parts as those of the first embodiment are denoted by the same reference numerals, and only the differences will be described below.

  That is, in this embodiment, the electromagnetic on-off valve 66 is connected in the middle of the sub branch circuit 60b. Other configurations are the same as those of the first embodiment.

  In this embodiment, at the time of defrosting in a state where the wafer is not formed in the vacuum chamber 120 of the vacuum film forming apparatus A shown in FIG. 1, the sub branch circuit 60b is opened by opening the electromagnetic on-off valve 66. As in the first embodiment, the defrost circuit 60 is opened by opening the electromagnetic on-off valve 61 and the main refrigerant pipe 2a is closed by closing the electromagnetic on-off valve 62, so that the high-temperature gas refrigerant discharged from the compressor 20 is defrosted. While being supplied from the main branch circuit 60a of the circuit 60 to the cryocoil 52, it is also supplied from the sub-branch circuit 60b to the fourth heat exchanger 43 to capture moisture and the like in the cryocoil 52 and the fourth heat exchanger 43. Release of is started at the same time.

  When the temperature of the fourth heat exchanger 43 is raised to the lubricating oil pour point (for example, −50 ° C.) or more, the electromagnetic on-off valve 66 is closed and the sub-branch circuit 60b is closed. The gas refrigerant in the defrost circuit 60 flows only to the main branch circuit 60a and is supplied to the cryocoil 52, and the high-temperature gas refrigerant that has been branched to the main branch circuit 60a and the sub-branch circuit 60b is used as the main branch circuit. The temperature of the cryocoil 52 can be raised by circulating only through 60a, and the defrosting operation time can be further shortened.

  As described above, according to the present invention, for the ultra-low temperature refrigeration apparatus provided with the defrost circuit, the lubricating oil or the like in the mixed refrigerant is supplied from the defrost circuit to the cooler at the time of defrosting and then solidifies in the heat exchanger. Can be suppressed and the defrosting operation time can be shortened, and a highly practical effect can be obtained. Therefore, it is extremely useful and has high industrial applicability.

It is a schematic explanatory drawing of the vacuum film-forming apparatus which concerns on embodiment of this invention. It is another schematic explanatory drawing of a vacuum film-forming apparatus. It is a refrigerant | coolant system diagram which shows the whole structure of the ultra-low-temperature freezing apparatus which concerns on Embodiment 1 of this invention. FIG. 4 is a view corresponding to FIG. 3 showing Embodiment 2 of the present invention.

Explanation of symbols

10 Ultra-low temperature refrigeration equipment 20 Compressor 21 Water-cooled condenser (condenser)
22 Auxiliary condenser (condenser)
24 1st gas-liquid separator 25 1st heat exchanger 30 2nd gas-liquid separator 31 2nd heat exchanger 36 3rd gas-liquid separator 37 3rd heat exchanger 42 4th gas-liquid separator 43 4th heat Exchanger 52 Cryocoil (cooler)
60 Defrost circuit 60a Main branch circuit 60b Sub branch circuit 66 Electromagnetic on-off valve

Claims (2)

A compressor that compresses a mixed refrigerant in which a plurality of types of refrigerants having different boiling points are mixed;
A condenser that cools and liquefies a high boiling point refrigerant among the mixed refrigerant discharged from the compressor;
A multi-stage gas-liquid separator that sequentially separates the mixed refrigerant liquefied by the condenser from a high boiling point refrigerant into a low boiling point refrigerant into a liquid refrigerant and a gas refrigerant;
A plurality of stages in which the primary-side gas refrigerant separated by each gas-liquid separator is cooled by heat exchange with the secondary-side liquid refrigerant separated and decompressed by each gas-liquid separator. A cascade heat exchanger,
A refrigerant circuit that is connected to a cooler that evaporates the low-boiling-point refrigerant that has flowed out from the cascade heat exchanger at the final stage of the plurality of stages and cools the object to be cooled to an ultra-low temperature level, and
In the ultra-low temperature refrigeration apparatus including a defrost circuit that supplies the mixed refrigerant discharged from the compressor to the cooler at the time of defrosting the cooler,
The downstream end of the defrost circuit branches into a main branch circuit and a sub branch circuit,
The downstream end of the main branch circuit is connected to the refrigerant circuit on the inlet side of the cooler, while the downstream end of the sub branch circuit is connected to the refrigerant circuit on the outlet side of the cooler. Ultra low temperature refrigeration equipment. In the ultra-low temperature refrigeration apparatus according to claim 1,
An ultra-low temperature refrigeration apparatus, wherein an opening / closing valve is provided in the sub-branch circuit.

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