Refrigeration device, temperature sensor mounting pipe, and temperature sensor mounting structure

This refrigeration device comprises: a high temperature side refrigerant circuit in which a high temperature side refrigerant circulates; a low temperature side refrigerant circuit in which a low temperature side refrigerant circulates; and a cascade heat exchanger that cools the low temperature side refrigerant with the high temperature side refrigerant. In the low temperature side refrigerant circuit, a low temperature side decompressor is disposed downstream of the cascade heat exchanger and a temperature sensor is installed in a piping portion between the cascade heat exchanger and the low temperature side decompressor.

TECHNICAL FIELD

The present disclosure relates to a refrigeration apparatus, and in particular to a refrigeration apparatus including a two-way refrigerant circuit, a temperature sensor attaching pipe and a temperature sensor attaching structure.

BACKGROUND ART

In the related art, a refrigeration apparatus that includes a two-way refrigerant circuit with a high-temperature side refrigerant circuit and a low-temperature side refrigerant circuit and cools the refrigerant in the low-temperature side refrigerant circuit by the refrigerant in the high-temperature side refrigerant circuit is used as disclosed in PTL 1, for example.

In general, in a refrigeration apparatus, the machine to be controlled such as a compressor is controlled such that the temperature of the storage unit in which the cooling object is disposed is set to the target temperature.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

In the case where a refrigeration apparatus has a two-way refrigerant circuit, the configuration is complicated due to the refrigerant circuits of two systems. Therefore, simple detection of the temperature inside the storage unit and control of the machine to be controlled to set its temperature to the target temperature alone may not necessarily achieve efficient operation.

An object of the present disclosure is to more efficiently operate a refrigeration apparatus.

Solution to Problem

A refrigeration apparatus according to the present disclosure includes: a high-temperature side refrigerant circuit in which high-temperature side refrigerant circulates; a low-temperature side refrigerant circuit in which low-temperature side refrigerant circulates; and a cascade heat exchanger configured to cool the low-temperature side refrigerant by using the high-temperature side refrigerant. In the low-temperature side refrigerant circuit, a low-temperature side decompressor is disposed on a downstream of the cascade heat exchanger, and a temperature sensor is installed at a pipe part between the cascade heat exchanger and the low-temperature side decompressor.

Advantageous Effects of Invention

According to the present disclosure, it is possible to more efficiently operate a refrigeration apparatus.

DESCRIPTION OF EMBODIMENTS

An embodiment of the present disclosure is described in detail below with reference to the accompanying drawings. Note that Embodiment described below is merely an example, and the present disclosure is not limited to the present embodiment.

FIG.1illustrates an exemplary refrigerant circuit provided in a refrigeration apparatus according to Embodiment 1 of the present disclosure. Refrigerant circuit1is provided in a refrigeration apparatus such as an ultra-low-temperature freezer in which the inner temperature of the storage unit is −80° C. or below, for example.

Refrigerant circuit1is a two-way refrigerant circuit including high-temperature side refrigerant circuit10and low-temperature side refrigerant circuit20in which refrigerant is circulated independently of each other.

High-temperature side evaporator14is the outer pipe of cascade heat exchanger30described later, and surrounds second heat exchanger23described later.

The above-mentioned devices are connected through a predetermined pipe (high-temperature side pipe) such that the refrigerant (high-temperature side refrigerant) discharged from high-temperature side compressor11again returns to high-temperature side compressor11. The high-temperature side refrigerant circulates in the arrow direction ofFIG.1. Specifically, in high-temperature side refrigerant circuit10, the high-temperature side refrigerant flows through high-temperature side compressor11, high-temperature side condenser12, dryer15, high-temperature side decompressor13, high-temperature side evaporator14, and liquid receiver16in this order, and returns back to high-temperature side compressor11. Note that the temperature can be reduced to approximately −40° C. at high-temperature side evaporator14through the freezing cycle in high-temperature side refrigerant circuit10.

The above-mentioned devices are connected through a predetermined pipe (low-temperature side pipe) such that the refrigerant (low-temperature side refrigerant) discharged from low-temperature side compressor21again returns to low-temperature side compressor21. The low-temperature side refrigerant circulates in the arrow direction ofFIG.1. Specifically, in low-temperature side refrigerant circuit20, the low-temperature side refrigerant flows through low-temperature side compressor21, first heat exchanger22, second heat exchanger23, large surface area part26, low-temperature side decompressor24, and low-temperature side evaporator25in this order, and returns back to low-temperature side compressor21. Note that an ultra-low temperature of −80° C. or below can be obtained at low-temperature side evaporator25through the freezing cycle in low-temperature side refrigerant circuit20.

First heat exchanger22cools the refrigerant passing through its inside in the gas phase. Note that first heat exchanger22may be a condenser that condenses the refrigerant passing through its inside.

Second heat exchanger23is the inner pipe of cascade heat exchanger30. Specifically, second heat exchanger23serving as the inner pipe is surrounded by high-temperature side evaporator14serving as the outer pipe. In cascade heat exchanger30, the heat is exchanged between the low temperature refrigerant passing inside high-temperature side evaporator14, and the high temperature refrigerant passing inside second heat exchanger23. At this time, the high temperature refrigerant passing inside second heat exchanger23condenses. Note that in the case where first heat exchanger22is a condenser, second heat exchanger23cools the refrigerant in the liquid phase passing through its inside.

In addition, large surface area part26in which the low-temperature side refrigerant flows is disposed between upstream side pipe26alocated on the downstream side of second heat exchanger23and downstream side pipe26blocated on the upstream side of low-temperature side decompressor24. Large surface area part26is a portion with a larger surface area per unit length in the direction in which the refrigerant flows, than the low-temperature side pipe, especially upstream side pipe26aand downstream side pipe26b. Large surface area part26is, for example, a large diameter pipe or a container-shaped member. The large diameter pipe is a pipe with a larger volume per unit length in the direction in which the refrigerant flows than at least upstream side pipe26aand downstream side pipe26b. In addition, the container-shaped member is, for example, a dehydrator that adsorbs the moisture inside low-temperature side refrigerant circuit20. In addition, large surface area part26may be a pipe with the same internal diameter as the internal diameter of upstream side pipe26aand downstream side pipe26b, and a thickness greater than that of upstream side pipe26aand downstream side pipe26b. In the following description, large surface area part26is assumed as a container-shaped member.

Upstream side pipe26ais connected to large surface area part26from the upstream side. Upstream side pipe26amay connect between second heat exchanger23and large surface area part26.

Downstream side pipe26bis connected to large surface area part26from the downstream side. Downstream side pipe26bmay connect between large surface area part26and low-temperature side decompressor24.

In addition, the refrigerant that flows into large surface area part26is liquid.

Thus, large surface area part26temporarily stores the liquid refrigerant (low-temperature side refrigerant) that flows into large surface area part26from the upstream side and flows out to the downstream side of large surface area part26. In other words, it flows at a relatively low speed inside large surface area part26. Temperature sensor T1that detects the temperature of the refrigerant passing through its inside is installed at the surface of large surface area part26.

Each of high-temperature side refrigerant circuit10and low-temperature side refrigerant circuit20may include an auxiliary machine not illustrated in the drawing. In the case where the auxiliary machines are disposed between second heat exchanger23and low-temperature side decompressor24in low-temperature side refrigerant circuit20, temperature sensor T1may be installed on the surface of the auxiliary machines.

The detection value of temperature sensor T1is input to controller40provided in refrigeration apparatus. Controller40controls at least one of an inverter that adjusts high-temperature side compressor11or its rotational frequency, and an inverter that adjusts low-temperature side compressor21or its rotational frequency on the basis of the set temperature of the storage unit, the detection value of temperature sensor T1and the like. Note that it goes without saying that refrigeration apparatus may include a temperature sensor other than temperature sensor T1such as a temperature sensor that detects the temperature inside the storage unit, and that controller40may control the machine to be controlled on the basis of the detection value of a plurality of temperature sensors including temperature sensor T1.

In refrigerant circuit1having the above-mentioned configuration, the cooling object disposed in the storage unit is cooled by the refrigerant flowing inside low-temperature side evaporator25, i.e., the refrigerant (low-temperature side refrigerant) circulating inside low-temperature side refrigerant circuit20. In addition, temperature sensor T1is installed on low-temperature side refrigerant circuit20side.

That is, temperature sensor T1can detect the temperature of the low-temperature side refrigerant that directly acts on the cooling of the cooling object, not the temperature of the high-temperature side refrigerant that indirectly acts on the cooling of the cooling object. Thus, more efficient operation of refrigerant circuit1can be achieved by controlling the machine to be controlled such as high-temperature side compressor11or low-temperature side compressor21by using the detection value of temperature sensor T1.

Moreover, temperature sensor T1is installed at a position where refrigerant in the liquid phase, not gas phase or gas-liquid mixed state, flows, or more specifically, at the pipe part located on the downstream side of second heat exchanger23and on the upstream side low-temperature side decompressor24. Liquid has a larger thermal conductivity than gas. Thus, in the case where the temperature of the flowing refrigerant is changed, the temperature change of the refrigerant can be detected more quickly at the portion where the refrigerant in the liquid phase flows than at the portion where the refrigerant in the gas phase flows. That is, according to the present embodiment, the temperature change of the refrigerant flowing through the low-temperature side refrigerant circuit can be detected more quickly, and in turn, more efficient operation of refrigerant circuit1can be achieved.

In addition, low-temperature side evaporator25, which is a portion where the refrigerant with the lowest temperature in refrigerant circuit1flows, is sealed in a heat insulation material and disposed to surround the storage unit where the cooling object disposed. As such, if temperature sensor T1is installed at low-temperature side evaporator25or the pipe in the vicinity of low-temperature side evaporator25on its upstream or downstream side, temperature sensor T1is also sealed in the heat insulation material, thus making it necessary to peel off the heat insulation material at the maintenance. That is, this makes it difficult to perform the maintenance of temperature sensor T1. In the present embodiment, on the other hand, temperature sensor T1is disposed at a portion between second heat exchanger23and low-temperature side decompressor24, i.e., a portion that need not necessarily be sealed in the heat insulation material. Thus, according to the present embodiment, the maintenance of temperature sensor T1or its attaching structure can be readily performed.

Note that the temperature of the refrigerant flowing inside large surface area part26is sufficiently lower than the outside air, while it is higher than the refrigerant flowing inside low-temperature side evaporator25. As such, there is a possibility of adhesion of condensation water or ice to large surface area part26, i.e., a portion around temperature sensor T1. If condensation water adheres to a portion around temperature sensor T1, the detection temperature may become inaccurate. In addition, if ice adheres to it, temperature sensor T1may be damaged.

To prevent the occurrence of such a situation, it is possible to use a temperature sensor attaching pipe for housing temperature sensor T1in the state where it is blocked from the outside air.FIG.2is a front view of temperature sensor attaching pipe101according to Embodiment 1.FIG.3is a cross-sectional view taken along A-A ofFIG.2, i.e., a longitudinal sectional view of temperature sensor attaching pipe101.

Temperature sensor attaching pipe101is formed by processing a pipe made of metal such as copper. One end of temperature sensor attaching pipe101is open, and makes up opening end part102.FIG.2andFIG.3illustrate temperature sensor attaching pipe101in which opening end part102is disposed on the upper side. The following description assumes that opening end part102is located on the upper side, but it goes without saying that opening end part102need not necessarily be located on the upper side.

The other end of temperature sensor attaching pipe101is sealed, and makes up seal end part103. Seal end part103is formed in such a manner that the other end of temperature sensor attaching pipe101is caulked into such a state as two overlapping flat plates, and then the opposite plate-shaped portions are welded together to seal the gap between the opposite portions with welding part103a. For the purpose of complete sealing, welding part103aextends to the right end from the left end of plate-shaped portion.

Constricted part104is formed by caulking a portion between opening end part102and seal end part103. While a gap is left inside constricted part104in the example illustrated inFIG.2, constricted part104may be formed with no gap through caulking.

First intermediate part105is formed between opening end part102and constricted part104. First intermediate part105is a portion with a hollow pipe shape whose one end is constricted.

Second intermediate part106is formed between seal end part103and constricted part104. Second intermediate part106is a portion with a hollow pipe shape whose both ends are constricted. The distance between seal end part103and constricted part104, i.e., the length of second intermediate part106is greater than the length of welding part103a.

FIG.3illustrates temperature sensor T1inserted to temperature sensor attaching pipe101from the opening end part. Temperature sensor T1is placed on constricted part104. Note that temperature sensor T1may be sandwiched by constricted part104. With temperature sensor attaching pipe101, a position of temperature sensor T1can be set at a predetermined position not only when it is placed on constricted part104, but also when it is sandwiched by constricted part104.

FIG.4is a diagram illustrating a temperature sensor attaching structure according to Embodiment 1 of the present disclosure. Temperature sensor attaching pipe101is attached to metal large surface area part26by welding. To be more specific, first intermediate part105is welded to large surface area part26such that welding part105ais formed.

In addition, temperature sensor attaching pipe101is attached such that temperature sensor T1disposed in its inside, i.e., constricted part104is located at the center of large surface area part26in front view. By attaching it at such a position, the surface temperature of large surface area part26can be uniformly detected, and the temperature of the liquid in large surface area part26can be more correctly measured.

First intermediate part105is longer than the other parts that make up temperature sensor attaching pipe101. Thus, the length of welding part105acan be sufficiently ensured, and temperature sensor attaching pipe101can be reliably attached to large surface area part26. Note that as long as temperature sensor attaching pipe101is reliably attached to large surface area part26, the length and position of welding part105aare not particularly limited.

When attaching temperature sensor attaching pipe101to large surface area part26by welding, heat is generated and transferred to temperature sensor attaching pipe101. It should be noted that a sufficient distance is ensured between seal end part103and constricted part104. To be more specific, as described above, the distance between seal end part103and constricted part104is greater than the length of welding part103a. Thus, in the heat generated when attaching temperature sensor attaching pipe101to large surface area part26by welding, the amount of the heat transferred to seal end part103is sufficiently small, and the temperature rise at seal end part103is small. Thus, it is possible to prevent a situation where the sealing at seal end part103becomes insufficient due to welding part103amelted at seal end part103when attaching temperature sensor attaching pipe101to large surface area part26by welding.

After it is attached by welding, temperature sensor T1is inserted to the inside of temperature sensor attaching pipe101through opening end part102. Since temperature sensor T1is placed on constricted part104as described above, the position of temperature sensor T1can be set at a predetermined position.

Note that as described above, temperature sensor T1may be sandwiched by constricted part104. In the case where temperature sensor T1is sandwiched by constricted part104, temperature sensor T1does not rattle inside temperature sensor attaching pipe101even when large surface area part26vibrates under the influence of high-temperature side compressor11or low-temperature side compressor21, for example, and it is possible to maintain the state where it is in contact with large surface area part26through temperature sensor attaching pipe101at all time. That is, the temperature of the refrigerant can be more correctly measured. In addition, with temperature sensor attaching pipe101, the position of temperature sensor T1can be set at a predetermined position not only when it is placed on constricted part104but also when it is sandwiched by constricted part104.

After temperature sensor T1is inserted, the opening of opening end part102is sealed by a sealing member of a paste form (not illustrated in the drawing), for example. In this manner, temperature sensor attaching pipe101is completely blocked from the outside air. Thus, for example, even in the case where large surface area part26has a low temperature or an extremely low temperature, it is possible to prevent inaccuracy of the temperature measurement due to adhesion, to temperature sensor T1, of water droplets generated by condensed moisture in the atmosphere, and damage to temperature sensor T1due to adhesion of ice.

Note that seal end part103may be sealed by welding part103abefore temperature sensor attaching pipe101is attached to large surface area part26, or may be sealed by welding part103aafter it is attached to large surface area part26through welding part105a. In any case, the lower end part of temperature sensor attaching pipe101can be easily sealed in comparison with the case where it is sealed using, for example, a sealing member of a paste form since it can be sealed by only sealing welding end part103. In the case where seal end part103is sealed after temperature sensor attaching pipe101is attached to large surface area part26and it is sealed using a sealing member of a paste form, it is especially advantageous since the operation posture tends to be unstable.

Note that seal end part103can be sealed through an easy operation in the case where seal end part103is sealed after temperature sensor attaching pipe101is attached to large surface area part26by employing the method in which opposite plate-shaped portions of seal end part103are sealed in the state where they are in contact with each other as a sealing method of seal end part103. That is, in the case where sealing is performed without using a sealing member, it is not necessarily be sealed by welding part103a.

Various methods may be employed as a sealing method of seal end part103.

Seal end part103may be sealed through mechanical coupling such as caulking and pressing opposite plate-shaped portions of seal end part103together. Seal end part103may be sealed through material coupling such as braze welding, ultrasound welding, and welding. Alternatively, seal end part103may be sealed through chemical coupling such as adhesion.

When seal end part103is sealed by a combination of two or more of mechanical coupling, material coupling and chemical coupling, the sealing becomes more reliable, and temperature sensor T1in temperature sensor attaching pipe101can be more reliably blocked from the outside air.

Incidentally, in the related art, the fixing apparatus of the temperature sensor disclosed in PTL 2 (Japanese Patent Application Laid-Open No. H08-082308) is proposed, for example.

However, the fixing apparatus disclosed in PTL 2 requires a caulking operation after the temperature sensor is inserted to the fixing apparatus. As such, there is a problem of complicated attaching operation. In addition, in the fixing apparatus disclosed in PTL 2, the temperature sensor is exposed to the outside air. Consequently, in the case where a portion whose temperature is to be measured by the temperature sensor has a low temperature, the temperature measurement may become inaccurate due to condensation of the moisture in the outside air. Further, in the case where the portion whose temperature is to be measured by the temperature sensor has an extremely low temperature, the temperature sensor may be damaged due to coagulation of the moisture in the outside air.

Under such a circumstance, an object of the present disclosure is to provide a temperature sensor attaching pipe and a temperature sensor attaching structure that can easily attach temperature sensor, and can correctly measure the temperature without damaging the temperature sensor.

The temperature sensor attaching pipe according to the present disclosure is metallic, and includes an opening end part including an opening configured for insertion of a temperature sensor, a seal end part, and a constricted part disposed between the opening end part and the seal end part.

In addition, the temperature sensor attaching structure according to the present disclosure includes the temperature sensor attaching pipe and an object which is metallic and to which the temperature sensor attaching pipe is attached. A portion located between the opening end part and the constricted part is attached to the object by welding.

With the temperature sensor attaching pipe and the temperature sensor attaching structure according to the present disclosure, the temperature sensor can be easily attached, and the temperature can be correctly measured without damaging the temperature sensor.

Embodiment 2 of the present disclosure is described in detail below with reference to the accompanying drawings.

FIG.5is a front view of temperature sensor attaching pipe201according to Embodiment 2 of the present disclosure, andFIG.6is a cross-sectional view taken along A-A ofFIG.5, i.e., a longitudinal sectional view of the temperature sensor attaching pipe according to the present disclosure201. Temperature sensor attaching pipe201is formed by processing a pipe made of metal such as copper. One end of temperature sensor attaching pipe201is open, and makes up opening end part202.FIG.5andFIG.6illustrate temperature sensor attaching pipe201with opening end part202disposed at a location on the upper side. The following description assumes that opening end part202is located on the upper side, but it goes without saying that opening end part202need not necessarily be located on the upper side

The other end of temperature sensor attaching pipe201is sealed, and makes up seal end part203. Seal end part203is formed in such a manner that the other end of temperature sensor attaching pipe201is caulked into such a state as two flat plates being overlapped each other, and then the opposite plate-shaped portions are welded together to seal the gap between the opposite portions with welding part203a. For the purpose of complete sealing, welding part203aextends to the right end from the left end of plate-shaped portion.

Constricted part204is formed by caulking the portion between opening end part202and seal end part203. While a gap is left inside constricted part204in the example illustrated inFIG.5, constricted part204may be formed with no gap through caulking.

First intermediate part205is formed between opening end part202and constricted part204. First intermediate part205is a portion with a hollow pipe shape whose one end is constricted.

Second intermediate part206is formed between seal end part203and constricted part204. Second intermediate part206is a portion with a hollow pipe shape whose both ends are constricted. The distance between seal end part203and constricted part204, i.e., the length of second intermediate part206is greater than the length of welding part203a.

FIG.6illustrates temperature sensor T2inserted from the opening end part of temperature sensor attaching pipe201. Temperature sensor T2is placed on constricted part204.

FIG.7is a diagram illustrating a temperature sensor attaching structure according to Embodiment 2 of the present disclosure. Large surface area part207is an object to which temperature sensor attaching pipe201is to be attached and is made of metal. Temperature sensor attaching pipe201is attached by welding to large surface area part207. To be more specific, first intermediate part205is welded to large surface area part207such that welding part205ais formed.

Here, large surface area part207has a larger surface area per unit length in the direction in which the refrigerant flows than the pipe connected to large surface area part207from the upstream side and the pipe connected to large surface area part207from the downstream side. Large surface area part207is, for example, a large diameter pipe or a container-shaped member. The large diameter pipe is a pipe with a larger volume per unit length in the direction in which the refrigerant flows, than the pipe connected to at least large surface area part207. In addition, the container-shaped member is, for example, a dehydrator that adsorbs the moisture inside low-temperature side refrigerant circuit220. In addition, large surface area part207may be a pipe with the same internal diameter as the internal diameter of pipe connected to large surface area part207, and a thickness larger than that of the pipe. In the following description, large surface area part207is assumed as a container-shaped member.

In addition, temperature sensor attaching pipe201is attached such that temperature sensor T2disposed in its inside, i.e., constricted part204is located at the center of large surface area part207in front view. By attaching it at such a position, the surface temperature of large surface area part207can be uniformly detected, and the temperature of the liquid inside large surface area part207can be more correctly measured.

First intermediate part205is longer than longer than the other parts that make up temperature sensor attaching pipe201. Thus, the length of welding part205acan be sufficiently ensured, and temperature sensor attaching pipe201can be reliably attached to large surface area part207. Note that as long as temperature sensor attaching pipe201can be reliably attached to large surface area part207, the length and position of welding part205aare not particularly limited.

When attaching temperature sensor attaching pipe201to large surface area part207by welding, heat is generated and transferred to temperature sensor attaching pipe201. It should be noted that a sufficient distance is ensured between seal end part203and constricted part204. To be more specific, as described above, the distance between seal end part203and constricted part204is greater than the length of welding part203a. Thus, in the heat generated when attaching temperature sensor attaching pipe201to large surface area part207by welding, the amount of the heat transferred to seal end part203is sufficiently small, and the temperature rise at seal end part203is small. Thus, it is possible to prevent a situation where the sealing of seal end part203becomes insufficient due to melting of welding part203aat seal end part203when attaching temperature sensor attaching pipe201to large surface area part207by welding.

After it is attached by welding, temperature sensor T2is inserted to the inside of temperature sensor attaching pipe201through opening end part202. Since temperature sensor T2is placed on constricted part204as described above, a position of temperature sensor T2can be set at a predetermined position.

Note that temperature sensor T2may be sandwiched by constricted part204. In the case where temperature sensor T2is sandwiched by constricted part204, even when the object such as large surface area part207is a vibrating member, temperature sensor T2does not rattle inside temperature sensor attaching pipe201and it is possible to maintain the state where it is in contact with the object through temperature sensor attaching pipe201at all time. That is, the temperature of the measurement target object can be more correctly measured. With temperature sensor attaching pipe201, the position of temperature sensor T2can be set at a predetermined position also when it is sandwiched by constricted part204as when it is placed on constricted part204.

After temperature sensor T2is inserted, the opening of opening end part202is sealed by a sealing member of a paste form (not illustrated in the drawing), for example. In this manner, temperature sensor attaching pipe201is completely blocked from the outside air. Thus, for example, even in the case where the object such as large surface area part207has a low temperature or an extremely low temperature, it is possible to prevent inaccuracy of the temperature measurement due to adhesion, to temperature sensor T2, of water droplets generated by condensed moisture in the atmosphere, and damage to temperature sensor T2due to adhesion of ice.

Note that seal end part203may be sealed by welding part203abefore temperature sensor attaching pipe201is attached to large surface area part207, or may be sealed by welding part203aafter it is attached to large surface area part207through welding part205a. In any case, the lower end part of temperature sensor attaching pipe201can be easily sealed in comparison with the case where it is sealed using, for example, a sealing member of a paste form since it can be sealed by simply welding seal end part203. In the case where seal end part203is sealed after large surface area part207is attached to temperature sensor attaching pipe201and it is sealed using a sealing member of a paste form, it is especially advantageous since the operation posture tends to be unstable.

Note that seal end part203can be sealed through an easy operation in the case where seal end part203is sealed after temperature sensor attaching pipe201is attached to large surface area part207by employing a method in which the opposite plate-shaped portions of seal end part203are sealed in the state where they are in contact with each other as a sealing method of seal end part203. That is, in the case where sealing is performed without using a sealing member, it is not necessarily be sealed by welding part203a.

Various methods may be employed as a sealing method of seal end part203. Seal end part203may be sealed through mechanical coupling such as caulking and pressing opposite plate-shaped portions of seal end part203together. Seal end part203may be sealed through material coupling such as braze welding, ultrasound welding, and welding. Alternatively, seal end part203may be sealed through chemical coupling such as adhesion.

When seal end part203is sealed by a combination of two or more of mechanical coupling, material coupling and chemical coupling, the sealing becomes more reliable, and temperature sensor T2in temperature sensor attaching pipe201can be more reliably blocked from the outside air.

Next, specific examples to which temperature sensor attaching pipe201and the temperature sensor attaching structure according to the present disclosure are applied is described.

FIG.8illustrates an exemplary refrigeration apparatus including a refrigerant circuit according to Embodiment 2 of the present disclosure. Refrigerant circuit200is provided in a refrigeration apparatus such as an ultra-low-temperature freezer in which the inner temperature of the storage unit is −80° C. or below, for example.

Refrigerant circuit200is a two-way refrigerant circuit including high-temperature side refrigerant circuit210and low-temperature side refrigerant circuit220in which refrigerant is circulated independently of each other.

High-temperature side evaporator214is the outer pipe of cascade heat exchanger230described later.

The above-mentioned devices are connected through a predetermined pipe (high-temperature side pipe) such that the refrigerant discharged from high-temperature side compressor211again returns to high-temperature side compressor211. The high-temperature side refrigerant circulates in the arrow direction ofFIG.8. Specifically, in high-temperature side refrigerant circuit210, the high-temperature side refrigerant flows through high-temperature side compressor211, high-temperature side condenser212, dryer215, high-temperature side decompressor213, high-temperature side evaporator214, and liquid receiver216in this order, and returns back to high-temperature side compressor211. Note that the temperature can be reduced to approximately −40° C. at high-temperature side evaporator214through the freezing cycle in high-temperature side refrigerant circuit210.

The above-mentioned devices are connected through a predetermined pipe (low-temperature side pipe) such that the refrigerant discharged from low-temperature side compressor221again returns to low-temperature side compressor221. The low-temperature side refrigerant circulates in the arrow direction ofFIG.8. Specifically, in low-temperature side refrigerant circuit220, the low-temperature side refrigerant flows through low-temperature side compressor221, first heat exchanger222, second heat exchanger223, large surface area part207, low-temperature side decompressor224, and low-temperature side evaporator225in this order, and returns back to low-temperature side compressor221. Note that an ultra-low temperature of −80° C. or below can be obtained at low-temperature side evaporator225through the freezing cycle in low-temperature side refrigerant circuit220.

First heat exchanger222cools the refrigerant passing through its inside in the gas phase. Note that first heat exchanger222may be a condenser that condenses the refrigerant passing through its inside.

Second heat exchanger223is the inner pipe of cascade heat exchanger230. Specifically, second heat exchanger223serving as the inner pipe is surrounded by high-temperature side evaporator214serving as the outer pipe. In cascade heat exchanger230, the heat is exchanged between the low temperature refrigerant passing inside high-temperature side evaporator214and the high temperature refrigerant passing inside second heat exchanger223. At this time, the high temperature refrigerant passing inside second heat exchanger223condenses. Note that in the case where first heat exchanger222is a condenser, second heat exchanger223cools the refrigerant in the liquid phase passing through its inside.

In addition, large surface area part207is disposed on the downstream side of second heat exchanger223and on the upstream side of low-temperature side decompressor224. Large surface area part207may be covered with a heat insulation material formed by foaming agent. In this case, temperature sensor attaching pipe201is also covered with the heat insulation material. However, since temperature sensor attaching pipe201is completely sealed as described above, the foaming agent does not enter temperature sensor attaching pipe201. Thus, since the foaming agent is not interposed between temperature sensor T2and large surface area part207, the temperature of the measurement target object can be more correctly measured.

In addition, the refrigerant that flows into large surface area part207is liquid.

Thus, large surface area part207temporarily stores the liquid refrigerant that flows into large surface area part207from the upstream side and flows out to the downstream side of large surface area part207. In other words, it flows at a relatively low speed inside large surface area part207. Then, the temperature of the refrigerant passing through large surface area part207can be immediately transmitted to temperature sensor T2through large surface area part207, welding part205aand temperature sensor attaching pipe201.

Each of high-temperature side refrigerant circuit210and low-temperature side refrigerant circuit220may include an auxiliary machine not illustrated in the drawing. In addition, the auxiliary machines may be a portion to which temperature sensor attaching pipe201is attached.

The refrigeration apparatus including refrigerant circuit200includes controller240. Controller240controls the rotational frequency and the like of high-temperature side compressor211and low-temperature side compressor221on the basis of the set temperature of the storage unit and the temperature detected by temperature sensor T2and the like. With the temperature sensor attaching structure including temperature sensor attaching pipe201and temperature sensor attaching pipe201, the temperature of the refrigerant inside large surface area part207can be more correctly measured. Thus, the rotational frequency and the like of high-temperature side compressor211and low-temperature side compressor221can be more appropriately controlled.

This application is a continuation of International Patent Application No. PCT/JP2020/024671, filed on Jun. 23, 2020, the disclosure of which is incorporated herein by reference in its entirety. International Patent Application No. PCT/JP2020/024671 is entitled to (or claims) the benefit of Japanese Patent Application No. 2019-132820 and No. 2019-132828, filed on Jul. 18, 2019, the disclosure of which is incorporated herein by reference in its entirety.

INDUSTRIAL APPLICABILITY

The refrigeration apparatus according to the present disclosure is suitable for a refrigeration apparatus including a two-way refrigerant circuit, such as an extremely low temperature freezer. Thus, its industrial applicability is wide. In addition, the temperature sensor attaching pipe and the temperature sensor attaching structure according to the present disclosure can be used for measurement of the temperature of a member composed of metal or an object inside it, such as a refrigeration apparatus including a refrigerant circuit. Thus, its industrial applicability is wide.

REFERENCE SIGNS LIST