JP2011007350A - Refrigerating device - Google Patents

Refrigerating device Download PDF

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JP2011007350A
JP2011007350A JP2009148457A JP2009148457A JP2011007350A JP 2011007350 A JP2011007350 A JP 2011007350A JP 2009148457 A JP2009148457 A JP 2009148457A JP 2009148457 A JP2009148457 A JP 2009148457A JP 2011007350 A JP2011007350 A JP 2011007350A
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pressure
refrigerant
compressor
state
stage compression
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JP5449881B2 (en
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Masahisa Otake
雅久 大竹
Hidetaka Sasaki
英孝 佐々木
Setsu Hasegawa
説 長谷川
Ken Kawakubo
賢 川久保
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Sanyo Electric Co Ltd
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Abstract

PROBLEM TO BE SOLVED: To provide a refrigerating device capable of eliminating the defective compression state of a compressor in an early period, and stably being operated with high efficiency.SOLUTION: The refrigerating device has a two-stage type compressor 11 having a low-stage compressing element 11A and a high-stage compressing element 11B, so that a refrigerant of intermediate pressure compressed by the low-stage compressing element 11A is guided to the high-stage compressing element 11B to be compressed, and a high-pressure refrigerant is discharged to a gas cooler 23, and furthermore, has a defective compression eliminating means for discriminating a refrigerant compression state in the compressor on the basis of the refrigerant pressure of intermediate pressure and high pressure, and eliminating the defective compression state by controlling high pressure to be higher than intermediate pressure in the case that the compression state of the refrigerant reaches the defective compression state that intermediate pressure is higher than high pressure, or in the case that it is estimated that the compression state of the refrigerant becomes the defective compression state.

Description

本発明は、低段圧縮要素及び高段圧縮要素を有する多段式圧縮機を備えた冷凍装置に関する。   The present invention relates to a refrigeration apparatus including a multistage compressor having a low-stage compression element and a high-stage compression element.

一般に、低段圧縮要素及び高段圧縮要素を備え、低段圧縮要素で圧縮された中間圧の冷媒を高段圧縮要素に導いて圧縮し、高圧の冷媒を放熱器に吐出する二段圧縮機を備え、放熱器に第一絞り手段及び蒸発器を順次接続して冷凍サイクルが構成された冷凍装置が知られている(例えば、特許文献1参照)。この種の冷凍装置では、第一絞り手段の絞り開度は、例えば、蒸発器の過熱度や圧縮機の吐出温度等に基づいて制御され、冷凍サイクルにおける適正な冷却運転が実行されている。
特開2007−255864号公報
Generally, a two-stage compressor that includes a low-stage compression element and a high-stage compression element, guides and compresses the intermediate-pressure refrigerant compressed by the low-stage compression element to the high-stage compression element, and discharges the high-pressure refrigerant to the radiator. There is known a refrigeration apparatus in which a refrigeration cycle is configured by sequentially connecting a first throttle means and an evaporator to a radiator (see, for example, Patent Document 1). In this type of refrigeration apparatus, the throttle opening of the first throttle means is controlled based on, for example, the degree of superheat of the evaporator, the discharge temperature of the compressor, etc., and an appropriate cooling operation in the refrigeration cycle is executed.
JP 2007-255864 A

ところで、上記した冷凍装置では、通常運転時、二段圧縮機の低段圧縮要素の吐出圧力(中間圧)は、高段圧縮要素の吐出圧力(高圧)よりも低いのが正常であるが、第一絞り手段の絞り開度が大きすぎる際には、この関係が逆転し、中間圧が高圧より高い状態(圧縮不良状態)となることがある。
すなわち、二段圧縮工程おいて、ある吸入状態での低段圧縮要素の吐出圧力(中間圧)は、低段圧縮要素と高段圧縮要素の容積比によって決まるのに対して、高段圧縮要素の吐出圧力(高圧)は第一絞り手段の絞り開度に依存するため、第一絞り手段の絞り開度が大きすぎると高圧が中間圧よりも低くなることがある。このような圧縮不良状態は、特に、冷凍装置の起動直後、除霜運転後もしくは蒸発温度(圧力)が高い場合に生じやすく、通常は、冷却運転中に、第一絞り手段の絞り開度が適正な開度に制御されることにより、圧縮不良状態は解消され、正常な状態、すなわち、高圧が中間圧より高い状態に復帰する。
By the way, in the above-described refrigeration apparatus, during normal operation, it is normal that the discharge pressure (intermediate pressure) of the low-stage compression element of the two-stage compressor is lower than the discharge pressure (high pressure) of the high-stage compression element. When the throttle opening of the first throttle means is too large, this relationship is reversed, and the intermediate pressure may be higher than the high pressure (compression failure state).
That is, in the two-stage compression process, the discharge pressure (intermediate pressure) of the low-stage compression element in a certain suction state is determined by the volume ratio of the low-stage compression element and the high-stage compression element, whereas the high-stage compression element Since the discharge pressure (high pressure) depends on the throttle opening of the first throttle means, if the throttle opening of the first throttle means is too large, the high pressure may be lower than the intermediate pressure. Such a compression failure state is likely to occur particularly immediately after the start of the refrigeration apparatus, after the defrosting operation, or when the evaporation temperature (pressure) is high. Usually, during the cooling operation, the throttle opening degree of the first throttle means is reduced. By controlling to an appropriate opening degree, the compression failure state is eliminated, and the normal state, that is, the state where the high pressure is higher than the intermediate pressure is restored.

しかし、通常運転中に圧縮不良状態が解消されるには時間がかかるため、早期に圧縮不良状態を解消することは難しかった。
さらに、第一絞り手段の絞り開度を、例えば、圧縮機の吐出温度等の冷媒温度に基づいて制御している場合には、圧縮機が圧縮不良状態に至っているにもかかわらず、制御対象とする温度(圧縮機の吐出温度)が目標温度に達することにより、第一絞り手段の絞り開度が安定してしまうこともある。この場合には、通常運転を継続したとしても、第一絞り手段の絞り開度が安定して変化しないため、圧縮不良状態が解消されず、正常な状態に復帰できない、または、復帰が遅れてしまう。
このため、圧縮不良状態での運転が継続されることにより、冷凍装置の冷却能力が著しく減少するとともに圧縮機の動力が増大し、冷凍サイクルの効率が低下するといった問題が生じるおそれがあった。
However, since it takes time to resolve the compression failure state during normal operation, it is difficult to resolve the compression failure state at an early stage.
Further, when the throttle opening degree of the first throttle means is controlled based on the refrigerant temperature such as the discharge temperature of the compressor, for example, the control target is controlled even though the compressor is in a poorly compressed state. When the temperature (the discharge temperature of the compressor) reaches the target temperature, the throttle opening degree of the first throttle means may be stabilized. In this case, even if the normal operation is continued, the throttle opening of the first throttle means does not change stably, so the compression failure state is not resolved and the normal state cannot be restored or the return is delayed. End up.
For this reason, when the operation in the state of poor compression is continued, there is a possibility that the cooling capacity of the refrigeration apparatus is remarkably reduced, the power of the compressor is increased, and the efficiency of the refrigeration cycle is lowered.

本発明は、上述した事情に鑑みてなされたものであり、圧縮機の圧縮不良状態を早期に解消し、安定かつ高効率な運転が可能な冷凍装置を提供することを目的とする。   The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a refrigeration apparatus that can eliminate a compression failure state of a compressor at an early stage and can perform a stable and highly efficient operation.

上述した課題を解決するため、本発明は、低段圧縮要素及び高段圧縮要素を備え、前記低段圧縮要素で圧縮された中間圧の冷媒を前記高段圧縮要素に導いて圧縮し、高圧の冷媒を放熱器に吐出する多段式の圧縮機を備え、前記放熱器に第一絞り手段及び蒸発器を順次接続して冷凍サイクルが構成される冷凍装置において、前記中間圧及び前記高圧の各冷媒圧力に基づいて前記圧縮機での冷媒の圧縮状態を判別する判別手段を備え、この判別手段により、前記冷媒の圧縮状態が、前記高圧よりも前記中間圧が高い圧縮不良状態に至った場合、または当該圧縮不良状態に至ると予想される場合に、前記高圧が前記中間圧よりも高くなるように制御されて当該圧縮不良状態を解消する圧縮不良解消手段を備えることを特徴とする。
ここで、冷媒の圧縮状態が圧縮不良状態に至ると予想される場合とは、中間圧と高圧とが接近して、中間圧及び高圧の各冷媒圧力の差圧が所定の値よりも小さくなることをいう。
In order to solve the above-described problems, the present invention includes a low-stage compression element and a high-stage compression element. The intermediate-pressure refrigerant compressed by the low-stage compression element is guided to the high-stage compression element and compressed. In the refrigeration system comprising a multistage compressor that discharges the refrigerant to the radiator, wherein a first refrigeration means and an evaporator are sequentially connected to the radiator to constitute a refrigeration cycle, each of the intermediate pressure and the high pressure A determination unit configured to determine a compression state of the refrigerant in the compressor based on a refrigerant pressure, and the determination unit causes the compression state of the refrigerant to reach a compression failure state in which the intermediate pressure is higher than the high pressure; Or a compression failure elimination means for eliminating the compression failure state by controlling the high pressure to be higher than the intermediate pressure when the compression failure state is expected.
Here, when the compressed state of the refrigerant is expected to reach a poorly compressed state, the intermediate pressure and the high pressure approach each other, and the differential pressure between the intermediate pressure and the high pressure refrigerant pressure becomes smaller than a predetermined value. That means.

本構成によれば、圧縮不良解消手段を制御することにより、高圧よりも中間圧が高い圧縮不良状態が早期に解消されて、圧縮機での冷媒の圧縮状態を、高圧が中間圧よりも高い正常な状態に復帰させることができる。このため、圧縮不良による圧縮機の入力の増大を防止でき、冷凍装置の安定かつ高効率な運転が可能となる。   According to this configuration, by controlling the compression failure elimination means, the compression failure state in which the intermediate pressure is higher than the high pressure is eliminated early, and the compression state of the refrigerant in the compressor is higher than the intermediate pressure. The normal state can be restored. For this reason, an increase in the input of the compressor due to poor compression can be prevented, and the refrigeration apparatus can be operated stably and efficiently.

上記構成において、前記放熱器から前記第一絞り手段へ向かう冷媒と、前記放熱器の出口側から分岐され、第二絞り手段を介して減圧された分岐冷媒との間で熱交換を行う熱交換器を備え、この熱交換器を出た分岐冷媒を中間圧となる前記高段圧縮要素の入口側に戻す構成とし、前記圧縮不良解消手段は、前記第二絞り手段の絞り開度を拡大し、前記中間圧の冷媒を前記高圧側に逆流させる構成としても良い。
この構成によれば、第二絞り手段の絞り開度を拡大することにより、分岐冷媒の流路を圧力逃がし回路として作用させることができる。このため、中間圧の冷媒を高圧側に逆流させることができ、圧縮不良状態が解消されて、冷媒の圧力状態を正常な状態に早期に復帰させることができる。この場合、例えば、冷媒の圧力状態が圧縮不良状態のまま、第一絞り手段の絞り開度が安定していたとしても、上記した第二絞り手段の絞り開度を拡大することにより、冷凍サイクル内の冷媒の圧力状態が変化するため、これに応じて第一絞り手段の絞り開度が調整され、冷媒の圧力状態を正常な状態に復帰させることができる。
In the above configuration, heat exchange is performed between the refrigerant from the radiator toward the first throttle means and the branched refrigerant branched from the outlet side of the radiator and depressurized via the second throttle means. A branch refrigerant that exits the heat exchanger is returned to the inlet side of the high-stage compression element that has an intermediate pressure, and the compression failure elimination means expands the throttle opening of the second throttle means. The intermediate pressure refrigerant may be made to flow backward to the high pressure side.
According to this configuration, it is possible to cause the flow path of the branched refrigerant to act as a pressure relief circuit by increasing the throttle opening of the second throttle means. For this reason, the intermediate-pressure refrigerant can be caused to flow back to the high-pressure side, the poor compression state is eliminated, and the refrigerant pressure state can be quickly returned to the normal state. In this case, for example, even if the throttle opening of the first throttle means is stable while the pressure state of the refrigerant remains in a poorly compressed state, the refrigeration cycle is increased by increasing the throttle opening of the second throttle means. Since the refrigerant pressure state changes, the throttle opening degree of the first throttle means is adjusted accordingly, and the refrigerant pressure state can be returned to the normal state.

また、前記圧縮不良解消手段は、前記第一絞り手段の絞り開度を縮小し、前記高段圧縮要素から吐出される高圧の冷媒圧力を高める構成としても良い。
この構成によれば、通常の冷却運転時の制御動作に優先して、第一絞り手段の絞り開度を縮小することにより、高段圧縮要素から吐出される高圧の冷媒圧力が高まるため、圧縮不良状態が解消されて、冷媒の圧力状態を正常な状態に早期に復帰させることができる。さらに、この構成では、例えば、冷媒の圧力状態が圧縮不良状態のまま、第一絞り手段の絞り開度が安定していたとしても、当該第一絞り手段の絞り開度を縮小することにより、冷凍サイクル内の冷媒の圧力状態を変化させることができ、当該圧力状態は正常な状態に復帰される。
The compression failure eliminating means may be configured to reduce the throttle opening of the first throttle means and increase the high-pressure refrigerant pressure discharged from the high-stage compression element.
According to this configuration, since the high-pressure refrigerant pressure discharged from the high-stage compression element is increased by reducing the throttle opening of the first throttle means in preference to the control operation during the normal cooling operation, the compression is performed. The defective state is eliminated, and the pressure state of the refrigerant can be quickly returned to the normal state. Furthermore, in this configuration, for example, even if the throttle opening of the first throttle means is stable while the pressure state of the refrigerant remains in a poorly compressed state, by reducing the throttle opening of the first throttle means, The pressure state of the refrigerant in the refrigeration cycle can be changed, and the pressure state is returned to a normal state.

また、前記低段側圧縮要素の入口側と前記高段側圧縮要素の入口側との間を連結する連結管と、この連結管に設けられる開閉弁とを備え、前記圧縮不良解消手段は、前記開閉弁を開放して、前記中間圧の冷媒を低圧側に流通させる構成としても良い。この構成によれば、連結管を通じて、中間圧の冷媒を低圧側に流通させることにより、当該中間圧を下げることができるため、圧縮不良状態が解消されて、冷媒の圧力状態を正常な状態に早期に復帰させることができる。   The compression failure elimination means includes a connecting pipe that connects the inlet side of the low-stage compression element and the inlet side of the high-stage compression element, and an on-off valve provided in the connecting pipe. The on-off valve may be opened to allow the intermediate pressure refrigerant to flow to the low pressure side. According to this configuration, since the intermediate pressure can be lowered by circulating the intermediate pressure refrigerant to the low pressure side through the connecting pipe, the compression failure state is eliminated, and the pressure state of the refrigerant is set to a normal state. It can be restored early.

また、前記圧縮機は周波数可変型の圧縮機であり、前記圧縮不良解消手段は、当該圧縮機の運転周波数を低減して運転する構成としても良い。この構成によれば、圧縮機の運転周波数を低減することにより、冷凍サイクル内の冷媒の圧縮状態が大きく変化するため、圧縮不良状態が解消されるとともに、冷媒の圧縮状態の変化に応じて第一絞り手段の絞り開度が調整されるため、冷媒の圧力状態を早期に正常な状態に復帰させることができる。   Further, the compressor may be a variable frequency compressor, and the compression failure elimination means may be configured to operate by reducing the operating frequency of the compressor. According to this configuration, since the compression state of the refrigerant in the refrigeration cycle is greatly changed by reducing the operating frequency of the compressor, the compression failure state is eliminated, and the first change is made according to the change in the refrigerant compression state. Since the throttle opening of one throttle means is adjusted, the pressure state of the refrigerant can be quickly returned to the normal state.

本発明によれば、圧縮不良解消手段を制御することにより、圧縮不良状態が早期に解消されて、高圧が中間圧よりも高い正常な状態に復帰させることができる。このため、圧縮不良による圧縮機の入力の増大を防止でき、冷凍装置の安定かつ高効率な運転が可能となる。   According to the present invention, by controlling the compression failure elimination means, the compression failure state can be eliminated at an early stage, and the high pressure can be returned to a normal state higher than the intermediate pressure. For this reason, an increase in the input of the compressor due to poor compression can be prevented, and the refrigeration apparatus can be operated stably and efficiently.

以下、本発明の実施の形態を添付の図面を参照しながら説明する。
(第1実施形態)
図1は、本実施形態に係る冷凍装置の冷媒回路を示す回路構成図である。
冷凍装置1は、冷凍機ユニット3と複数台(例えば2台)のショーケースユニット5A,5Bとを備え、これら冷凍機ユニット3と各ショーケースユニット5A,5Bとが、液冷媒配管7及びガス冷媒配管9により連結されて冷凍サイクルを構成する。この冷凍サイクルには、高圧側が超臨界圧力となるCO(二酸化炭素)冷媒が使用される。CO冷媒は、オゾン破壊係数が0で、地球温暖化係数が1であるため、環境への負荷が小さく、毒性、可燃性がなく安全で安価である。
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
(First embodiment)
FIG. 1 is a circuit configuration diagram showing a refrigerant circuit of the refrigeration apparatus according to the present embodiment.
The refrigeration apparatus 1 includes a refrigeration unit 3 and a plurality of (for example, two) showcase units 5A and 5B. The refrigeration unit 3 and the showcase units 5A and 5B include a liquid refrigerant pipe 7 and a gas. The refrigerant pipes 9 are connected to form a refrigeration cycle. In this refrigeration cycle, a CO 2 (carbon dioxide) refrigerant having a supercritical pressure on the high pressure side is used. Since the CO 2 refrigerant has an ozone depletion coefficient of 0 and a global warming coefficient of 1, the load on the environment is small, and it is safe and inexpensive without toxicity and flammability.

冷凍機ユニット3は、並列に配置された2台の圧縮機11,11を備える。この圧縮機11は、ケース12内が中間圧となる内部中間圧型のロータリ式二段圧縮機であり、ケース12内部に電動機部(図示略)と、この電動機部により駆動される低段圧縮要素11A及び高段圧縮要素11Bとが配置されている。低段圧縮要素11Aは、ガス冷媒配管9を通じて圧縮機11に吸い込まれる低圧の冷媒を中間圧まで昇圧して吐出し、高段圧縮要素11Bは、上記低段圧縮要素11Aで圧縮された中間圧の冷媒を更に高圧まで昇圧して吐出する。また、圧縮機11は、周波数可変型の圧縮機であり、電動機部の運転周波数を変更することにより、低段圧縮要素11A及び高段圧縮要素11Bの回転数が調整可能となっている。
圧縮機11のケース12には、低段圧縮要素11Aに連通する低段側吸込口12A及び低段側吐出口12Bと、高段圧縮要素11Bに連通する高段側吸込口12C及び高段側吐出口12Dとが形成されている。各圧縮機11,11の低段側吸込口12A,12Aには、それぞれ低圧吸入管13,13が接続され、これら低圧吸入管13,13は低段圧縮要素11A,11Aの上流側で合流し、アキュームレータ14を介して、ガス冷媒配管9に接続される。また、低圧吸入管13には、この低圧吸入管13を流れる冷媒の吸込圧力と吸込温度とをそれぞれ検出する吸込圧力センサー15と吸込温度センサー16とが設けられている。
The refrigerator unit 3 includes two compressors 11 and 11 arranged in parallel. The compressor 11 is an internal intermediate pressure type rotary two-stage compressor in which the inside of the case 12 has an intermediate pressure. An electric motor part (not shown) in the case 12 and a low-stage compression element driven by the electric motor part. 11A and the high stage compression element 11B are arranged. The low-stage compression element 11A boosts and discharges low-pressure refrigerant sucked into the compressor 11 through the gas refrigerant pipe 9 to an intermediate pressure, and the high-stage compression element 11B is an intermediate pressure compressed by the low-stage compression element 11A. The refrigerant is further pressurized to a high pressure and discharged. The compressor 11 is a variable frequency compressor, and the rotation speed of the low-stage compression element 11A and the high-stage compression element 11B can be adjusted by changing the operating frequency of the electric motor unit.
The case 12 of the compressor 11 includes a low-stage suction port 12A and a low-stage discharge port 12B communicating with the low-stage compression element 11A, and a high-stage suction port 12C and a high-stage side communicating with the high-stage compression element 11B. A discharge port 12D is formed. Low-pressure suction pipes 13 and 13 are connected to the low-stage suction ports 12A and 12A of the compressors 11 and 11, respectively, and these low-pressure suction pipes 13 and 13 merge on the upstream side of the low-stage compression elements 11A and 11A. The gas refrigerant pipe 9 is connected via an accumulator 14. Further, the low pressure suction pipe 13 is provided with a suction pressure sensor 15 and a suction temperature sensor 16 for detecting the suction pressure and the suction temperature of the refrigerant flowing through the low pressure suction pipe 13, respectively.

各低段側吐出口12B,12Bには、それぞれ中間圧吐出管17,17が接続され、この中間圧吐出管17,17は低段圧縮要素11A,11Aの下流側で合流して中間冷却器18の一端に接続される。この中間冷却器18は、低段圧縮要素11Aから吐出された中間圧の冷媒を冷却するものであり、当該中間冷却器18の他端には、中間圧吸入管19が接続され、この中間圧吸入管19は2つに分岐した後に高段側吸込口12C,12Cに接続される。また、中間圧吸入管19には、この中間圧吸入管19を流れる冷媒の中間圧力を検出する中間圧力センサー20が設けられている。本構成では、高段側吸込口12Cは、ケース12内空間を介して高段圧縮要素11Bに連通しており、圧縮機11の運転中、当該ケース12内は中間圧に保たれる。   Intermediate pressure discharge pipes 17 and 17 are connected to the low-stage discharge ports 12B and 12B, respectively, and the intermediate-pressure discharge pipes 17 and 17 merge at the downstream side of the low-stage compression elements 11A and 11A. 18 is connected to one end. This intermediate cooler 18 cools the intermediate-pressure refrigerant discharged from the low-stage compression element 11A, and an intermediate-pressure suction pipe 19 is connected to the other end of the intermediate cooler 18. The suction pipe 19 is branched into two and then connected to the high-stage suction ports 12C and 12C. Further, the intermediate pressure suction pipe 19 is provided with an intermediate pressure sensor 20 that detects the intermediate pressure of the refrigerant flowing through the intermediate pressure suction pipe 19. In this configuration, the high stage side suction port 12 </ b> C communicates with the high stage compression element 11 </ b> B through the space in the case 12, and the inside of the case 12 is maintained at an intermediate pressure during the operation of the compressor 11.

各高段側吐出口12D,12Dには、それぞれ高圧吐出管21,21が接続され、この高圧吐出管21,21は高段圧縮要素11B,11Bの下流側で合流し、オイルセパレータ22、ガスクーラー(放熱器)23及び過冷却熱交換器(熱交換器)24を介して、液冷媒配管7に接続される。また、高段側吐出口12D,12Dには、高段圧縮要素11B,11Bから吐出された冷媒の吐出圧力と吐出温度とをそれぞれ検出する吐出圧力センサー25と吐出温度センサー26とが設けられている。
オイルセパレータ22は、圧縮機11から吐出された高圧の吐出冷媒中に含まれるオイルを冷媒と分離して捕捉するものであり、このオイルセパレータ22には、捕捉したオイルを圧縮機11に戻すオイル戻し管28が接続されている。このオイル戻し管28には、捕捉したオイルを冷却するオイルクーラー27が設けられ、このオイルクーラー27の下流側で、オイル戻し管28は2系統に分岐され、それぞれストレーナ29及び流量調整弁(電動弁)30を介して圧縮機11のケース12に接続される。圧縮機11のケース12内は、上述のように中間圧に保たれるため、捕捉されたオイルは、オイルセパレータ22内の高圧とケース12内の中間圧との差圧によって当該ケース12内に戻される。また、圧縮機11のケース12には、このケース12内に保有するオイルのレベルを検出するオイルレベルセンサ31が設けられている。
High-pressure discharge pipes 21 and 21 are connected to the high-stage discharge ports 12D and 12D, respectively, and the high-pressure discharge pipes 21 and 21 merge on the downstream side of the high-stage compression elements 11B and 11B. The liquid refrigerant pipe 7 is connected via a cooler (heat radiator) 23 and a supercooling heat exchanger (heat exchanger) 24. The high-stage discharge ports 12D and 12D are provided with a discharge pressure sensor 25 and a discharge temperature sensor 26 for detecting the discharge pressure and discharge temperature of the refrigerant discharged from the high-stage compression elements 11B and 11B, respectively. Yes.
The oil separator 22 separates and captures the oil contained in the high-pressure discharged refrigerant discharged from the compressor 11 from the refrigerant. The oil separator 22 is an oil that returns the captured oil to the compressor 11. A return pipe 28 is connected. The oil return pipe 28 is provided with an oil cooler 27 that cools the captured oil. On the downstream side of the oil cooler 27, the oil return pipe 28 is branched into two systems, each of which includes a strainer 29 and a flow rate adjusting valve (electrically operated). Valve) 30 and is connected to the case 12 of the compressor 11. Since the inside of the case 12 of the compressor 11 is maintained at the intermediate pressure as described above, the trapped oil is contained in the case 12 due to the differential pressure between the high pressure in the oil separator 22 and the intermediate pressure in the case 12. Returned. The case 12 of the compressor 11 is provided with an oil level sensor 31 that detects the level of oil retained in the case 12.

ガスクーラー23は、圧縮機11から吐出された高圧の吐出冷媒を冷却するものであり、本構成では、ガスクーラー23は、上記した中間冷却器18及びオイルクーラー27に並設されている。これらガスクーラー23、中間冷却器18及びオイルクーラー27には、当該ガスクーラー23、中間冷却器18及びオイルクーラー27に向けて送風する冷却ファン32が隣接して設けられている。
過冷却熱交換器24は、ガスクーラー23で冷却され、ガスクーラー23から高圧吐出管21及び液冷媒配管7を通じて、ショーケースユニット5A,5Bが備える第一膨張弁(第一絞り手段)42A,42Bへ向かう冷媒を、このガスクーラー23の出口側で分岐された分岐冷媒を用いて過冷却するものである。この過冷却熱交換器24には、ガスクーラー23の出口側で高圧吐出管21から分岐された分岐配管33が、第二膨張弁(第二絞り手段)34を介して、中間冷却器18の出口側の中間圧吸入管19に接続されている。また、高圧吐出管21には、過冷却熱交換器24の入口側及び出口側に、それぞれ高圧吐出管21を流れる冷媒温度を検出する入口温度センサー35及び出口温度センサー36が設けられている。
The gas cooler 23 cools the high-pressure discharged refrigerant discharged from the compressor 11. In this configuration, the gas cooler 23 is arranged in parallel with the intermediate cooler 18 and the oil cooler 27 described above. The gas cooler 23, the intermediate cooler 18, and the oil cooler 27 are provided adjacent to a cooling fan 32 that blows air toward the gas cooler 23, the intermediate cooler 18, and the oil cooler 27.
The supercooling heat exchanger 24 is cooled by the gas cooler 23 and passes through the high pressure discharge pipe 21 and the liquid refrigerant pipe 7 from the gas cooler 23, and the first expansion valves (first throttle means) 42A included in the showcase units 5A and 5B. The refrigerant heading for 42B is supercooled using the branched refrigerant branched on the outlet side of the gas cooler 23. A branch pipe 33 branched from the high pressure discharge pipe 21 on the outlet side of the gas cooler 23 is connected to the subcooling heat exchanger 24 via a second expansion valve (second throttle means) 34. It is connected to the intermediate pressure suction pipe 19 on the outlet side. The high-pressure discharge pipe 21 is provided with an inlet temperature sensor 35 and an outlet temperature sensor 36 that detect the temperature of the refrigerant flowing through the high-pressure discharge pipe 21 on the inlet side and the outlet side of the supercooling heat exchanger 24, respectively.

また、冷凍機ユニット3は、冷凍装置1全体の動作を制御する主制御装置50を備える。この主制御装置50は、ショーケースユニット5A、5Bの冷凍負荷(具体的には、吸込圧力センサー15にて検出される吸込圧力)に応じて、圧縮機11,11の運転周波数を調整する。なお、圧縮機11,11の運転周波数を吐出圧力センサー25にて検出される吐出圧力に基づいて調整しても良い。また、主制御装置50は、吐出温度センサー26が検出する高段圧縮要素11Bの冷媒吐出温度に基づいて第二膨張弁34の開度(絞り開度)を調整する。なお、この第二膨張弁34の開度は、過冷却熱交換器24の中間圧となる分岐冷媒の出口温度、過冷却熱交換器24の冷媒の出入口温度差等に基づいて調整しても良い。   The refrigerator unit 3 includes a main controller 50 that controls the operation of the entire refrigeration apparatus 1. The main controller 50 adjusts the operating frequency of the compressors 11 and 11 according to the refrigeration load of the showcase units 5A and 5B (specifically, the suction pressure detected by the suction pressure sensor 15). The operating frequency of the compressors 11, 11 may be adjusted based on the discharge pressure detected by the discharge pressure sensor 25. The main controller 50 adjusts the opening (throttle opening) of the second expansion valve 34 based on the refrigerant discharge temperature of the high-stage compression element 11B detected by the discharge temperature sensor 26. The opening degree of the second expansion valve 34 may be adjusted based on the outlet temperature of the branch refrigerant, which is an intermediate pressure of the supercooling heat exchanger 24, the refrigerant inlet / outlet temperature difference of the supercooling heat exchanger 24, and the like. good.

一方、ショーケースユニット5A,5Bは、それぞれ店舗内等に設置され、液冷媒配管7及びガス冷媒配管9にそれぞれ並列に接続されている。各ショーケースユニット5A,5Bは、液冷媒配管7とガス冷媒配管9とを連結するケース冷媒配管40A,40Bを備え、これらケース冷媒配管40A,40Bには、それぞれストレーナ41A,41Bと、第一膨張弁(第一絞り手段)42A,42Bとケース熱交換器43A,43Bとが設けられている。このケース熱交換器43A,43Bには、当該ケース熱交換器43A,43Bに送風するケースファン44A,44Bが隣接して設けられている。
また、ショーケースユニット5A,5Bは、これらショーケースユニット5A,5Bの各部の動作を制御するケース制御装置45A,45Bを備える。このケース制御装置45A,45Bは、主制御装置50と通信可能に構成され、この主制御装置50から送信された上記高段圧縮要素11Bの冷媒吐出温度に基づいて、第一膨張弁42A,42Bの開度をそれぞれ調整する。なお、この第一膨張弁42A,42Bの開度は、ケース熱交換器43A,43Bの出入口温度差(過熱度)に基づいて、それぞれ調整しても良い。
On the other hand, the showcase units 5A and 5B are each installed in a store or the like, and are connected in parallel to the liquid refrigerant pipe 7 and the gas refrigerant pipe 9, respectively. Each showcase unit 5A, 5B includes case refrigerant pipes 40A, 40B that connect the liquid refrigerant pipe 7 and the gas refrigerant pipe 9, and the case refrigerant pipes 40A, 40B include strainers 41A, 41B, respectively, Expansion valves (first throttle means) 42A and 42B and case heat exchangers 43A and 43B are provided. The case heat exchangers 43A and 43B are provided with case fans 44A and 44B adjacent to the case heat exchangers 43A and 43B.
In addition, the showcase units 5A and 5B include case control devices 45A and 45B that control the operation of each part of the showcase units 5A and 5B. The case control devices 45A and 45B are configured to be communicable with the main control device 50, and based on the refrigerant discharge temperature of the high-stage compression element 11B transmitted from the main control device 50, the first expansion valves 42A and 42B. Adjust the opening of each. The opening degrees of the first expansion valves 42A and 42B may be adjusted based on the inlet / outlet temperature difference (superheat degree) of the case heat exchangers 43A and 43B.

ところで、この種の冷凍装置1では、通常の冷凍運転時、圧縮機11の低段圧縮要素11Aの吐出圧力(中間圧)は、高段圧縮要素11Bの吐出圧力(高圧)よりも低いのが正常であるが、特に、冷凍装置の起動直後、除霜運転後もしくは蒸発温度(圧力)が高い場合には、ショーケースユニット5A,5Bの第一膨張弁42A,42Bの開度が大きくなる傾向にあり、この開度が大きすぎると、上記した関係が逆転し、中間圧が高圧より高い状態(圧縮不良状態)となることがある。さらに、本実施形態では、第一膨張弁42A,42Bの開度は、高段圧縮要素11Bの冷媒吐出温度に基づいて調整されているため、圧縮機11が圧縮不良状態に至っているにもかかわらず、制御対象となる高段圧縮要素11Bの冷媒吐出温度が目標温度に達し、第一膨張弁42A,42Bの開度が所定の開度で安定してしまうこともある。このため、冷凍装置1が通常運転を継続したとしても、第一膨張弁42A,42Bの開度が安定して変化しないため、圧縮不良状態が解消されず、正常な状態に復帰できないといった問題が生じるおそれがある。
さらに、ケース内部が中間圧力となるロータリ式二段圧縮機では、高段圧縮要素11Bの吐出圧力(高圧)を背圧として利用し、この高段圧縮要素11Bのベーンの先端をロータに押し当てている。このため、圧縮不良状態となると、高圧と中間圧とが逆転することにより、高段圧縮要素11Bのベーンの先端をロータに押し当てる力が減少し、圧縮中の冷媒漏れ(ベーン飛び)が生じるため、圧縮機の動力が増大し、冷凍サイクルの効率が低下して冷却能力が著しく低下するおそれがある。
本構成では、上述した事情に鑑み、冷凍装置1は、中間圧及び高圧の各冷媒圧力に基づいて圧縮機11での冷媒の圧縮状態を判別する判別手段と、この冷媒の圧縮状態が圧縮不良状態に至った際に、当該圧縮不良状態を早期に解消するために、圧縮不良解消手段を備えている。この第1実施形態では、主制御装置50が冷媒の圧縮状態を判別する判別手段を構成し、上記した過冷却熱交換器24の分岐配管33に設けられた第二膨張弁34と、この第二膨張弁34の開度調整する主制御装置50が圧縮不良解消手段を構成する。
By the way, in this kind of refrigeration apparatus 1, during normal refrigeration operation, the discharge pressure (intermediate pressure) of the low-stage compression element 11A of the compressor 11 is lower than the discharge pressure (high pressure) of the high-stage compression element 11B. Although it is normal, the opening degree of the first expansion valves 42A and 42B of the showcase units 5A and 5B tends to increase, particularly when the refrigeration apparatus is started, after the defrosting operation or when the evaporation temperature (pressure) is high. If the opening is too large, the relationship described above is reversed, and the intermediate pressure may be higher than the high pressure (compressed state). Furthermore, in this embodiment, since the opening degree of the first expansion valves 42A and 42B is adjusted based on the refrigerant discharge temperature of the high-stage compression element 11B, the compressor 11 is in a poorly compressed state. Instead, the refrigerant discharge temperature of the high-stage compression element 11B to be controlled may reach the target temperature, and the opening degrees of the first expansion valves 42A and 42B may be stabilized at a predetermined opening degree. For this reason, even if the refrigeration apparatus 1 continues normal operation, the opening degree of the first expansion valves 42A and 42B does not change stably, and therefore, the compression failure state is not eliminated and the normal state cannot be restored. May occur.
Further, in a rotary type two-stage compressor in which the inside of the case has an intermediate pressure, the discharge pressure (high pressure) of the high-stage compression element 11B is used as a back pressure, and the tip of the vane of the high-stage compression element 11B is pressed against the rotor. ing. For this reason, when the compression failure state occurs, the high pressure and the intermediate pressure are reversed to reduce the force of pressing the vane tip of the high-stage compression element 11B against the rotor, resulting in refrigerant leakage (vane jump) during compression. For this reason, the power of the compressor is increased, the efficiency of the refrigeration cycle is decreased, and the cooling capacity may be significantly decreased.
In this configuration, in view of the above-described circumstances, the refrigeration apparatus 1 includes a determination unit that determines the compression state of the refrigerant in the compressor 11 based on the intermediate pressure and the high refrigerant pressure, and the compression state of the refrigerant is poorly compressed. In order to resolve the compression failure state at an early stage when the state is reached, a compression failure elimination means is provided. In the first embodiment, the main control device 50 constitutes a discriminating means for discriminating the compression state of the refrigerant, the second expansion valve 34 provided in the branch pipe 33 of the above-described supercooling heat exchanger 24, and the first The main controller 50 that adjusts the opening degree of the second expansion valve 34 constitutes a compression failure elimination means.

次に、圧縮不良状態を解消する際の動作について説明する。
図2は、この動作を示すフローチャートである。
冷凍装置1の運転が開始される(ステップS1)と、主制御装置50は、吐出圧力センサー25を介して吐出圧力(高圧圧力Ph)を検出(ステップS2)するとともに、中間圧力センサー20を介して中間圧力Pmを検出(ステップS3)し、これら各データを取得する。
また、主制御装置50は、吐出温度センサー26を介して吐出温度Tdisを検出(ステップS4)し、このデータを取得する。
Next, the operation for eliminating the compression failure state will be described.
FIG. 2 is a flowchart showing this operation.
When the operation of the refrigeration apparatus 1 is started (step S1), the main controller 50 detects the discharge pressure (high pressure Ph) via the discharge pressure sensor 25 (step S2) and also via the intermediate pressure sensor 20. The intermediate pressure Pm is detected (step S3), and each of these data is acquired.
Further, the main controller 50 detects the discharge temperature Tdis via the discharge temperature sensor 26 (step S4), and acquires this data.

続いて、主制御装置50は、高圧圧力Phと中間圧力Pmとを比較し、この高圧圧力Phと中間圧力Pmとの差圧(Ph−Pm)が所定の値よりも大きいか否かを判別する(ステップS5)。ここで、高圧圧力Phと中間圧力Pmとの差圧により、圧縮機11での冷媒の圧縮状態を把握することができ、正常な運転状態では、上記した差圧が所定の値よりも大きくなる。一方、上記した差圧が所定の値よりも小さくなると、中間圧と高圧とが接近した状態となるため、冷媒の圧縮状態が圧縮不良状態に至ると予想されると判断できる。
この判別において、高圧圧力Phと中間圧力Pmとの差圧が所定の値よりも大きい場合(ステップS5;Yes)には、圧縮機11での冷媒の圧縮状態は正常であるため、第二膨張弁34を通常の冷却運転時の制御に基づいて制御する。
具体的には、主制御装置50は、取得した吐出温度Tdisの値が目標値よりも大きいか否かを判別(ステップS6)する。本構成では、目標値の上下に所定幅の不感帯を設けて、第二膨張弁34の開度制御の頻度を抑えるのが望ましい。
この判別において、吐出温度Tdisの値が目標値よりも大きい(ステップS6;Yes)場合には、吐出温度Tdisの値が目標値に近づくように、第二膨張弁34を所定開度開くPID制御を行う(ステップS7)。また、吐出温度Tdisの値が目標値よりも小さい(ステップS6;No)場合には、吐出温度Tdisの値が目標値に近づくように、第二膨張弁34を所定開度閉じるPID制御を行い(ステップS8)、処理をステップS10に移行する。
Subsequently, the main controller 50 compares the high pressure Ph with the intermediate pressure Pm, and determines whether or not the differential pressure (Ph−Pm) between the high pressure Ph and the intermediate pressure Pm is greater than a predetermined value. (Step S5). Here, the compression state of the refrigerant in the compressor 11 can be grasped by the differential pressure between the high pressure Ph and the intermediate pressure Pm, and the above-described differential pressure becomes larger than a predetermined value in a normal operation state. . On the other hand, when the above-described differential pressure becomes smaller than a predetermined value, the intermediate pressure and the high pressure are brought close to each other, so that it can be determined that the compressed state of the refrigerant is expected to reach a poorly compressed state.
In this determination, when the differential pressure between the high pressure Ph and the intermediate pressure Pm is larger than a predetermined value (step S5; Yes), the refrigerant is compressed in the compressor 11 in a normal state, so the second expansion is performed. The valve 34 is controlled based on control during normal cooling operation.
Specifically, main controller 50 determines whether or not the acquired value of discharge temperature Tdis is greater than the target value (step S6). In this configuration, it is desirable to provide a dead band with a predetermined width above and below the target value to suppress the frequency of opening control of the second expansion valve 34.
In this determination, when the value of the discharge temperature Tdis is larger than the target value (step S6; Yes), PID control that opens the second expansion valve 34 by a predetermined opening so that the value of the discharge temperature Tdis approaches the target value. (Step S7). When the value of the discharge temperature Tdis is smaller than the target value (step S6; No), PID control is performed to close the second expansion valve 34 by a predetermined opening so that the value of the discharge temperature Tdis approaches the target value. (Step S8), the process proceeds to Step S10.

一方、ステップS5の判別において、高圧圧力Phと中間圧力Pmとの差圧が所定の値よりも小さい場合(ステップS5;No)には、中間圧と高圧とが接近して、冷媒の圧縮状態が圧縮不良状態に至ると予想されるため、主制御装置50は、この圧縮不良状態を解消するために、上述した通常の冷却運転時の制御によらず、第二膨張弁34を、当該冷却運転時の制御よりも大きい所定開度だけ開くように調整する(ステップS9)。
これによれば、図3に示すように、中間圧が高圧よりも高い圧縮不良状態にある場合であっても、時間T1にて、第二膨張弁34を所定開度開くことにより、分岐配管33を圧力逃がし回路として作用させることができる。このため、中間圧の冷媒を高圧側に逆流させることができ、圧縮不良状態が解消されて、冷媒の圧力状態を正常な状態に早期に復帰させることができる。
また、この構成では、第二膨張弁34を、通常の冷却運転時の制御よりも大きい所定開度だけ開くため、中間圧の冷媒圧力が第二膨張弁34を通過する際に減圧されることなく、高圧側に逆流し、早期に高圧側の圧力を高めることができる。
On the other hand, when the differential pressure between the high pressure Ph and the intermediate pressure Pm is smaller than a predetermined value in the determination in step S5 (step S5; No), the intermediate pressure and the high pressure approach each other and the refrigerant is compressed. Therefore, in order to eliminate this compression failure state, the main controller 50 causes the second expansion valve 34 to cool the second expansion valve 34 without depending on the control during the normal cooling operation described above. It adjusts so that only the predetermined opening degree larger than the control at the time of operation may open (step S9).
According to this, as shown in FIG. 3, even when the intermediate pressure is in a poorly compressed state higher than the high pressure, the branch pipe is opened by opening the second expansion valve 34 at a predetermined opening at time T1. 33 can act as a pressure relief circuit. For this reason, the intermediate-pressure refrigerant can be caused to flow back to the high-pressure side, the poor compression state is eliminated, and the refrigerant pressure state can be quickly returned to the normal state.
In this configuration, since the second expansion valve 34 is opened by a predetermined opening larger than the control during normal cooling operation, the intermediate refrigerant pressure is reduced when passing through the second expansion valve 34. However, it can flow backward to the high pressure side, and the pressure on the high pressure side can be increased early.

続いて、主制御装置50は、ケース制御装置45A,45Bを介して、第一膨張弁42A,42Bの開度を調整するとともに、圧縮機11の運転周波数を制御する(ステップS10)。このステップS10の制御は、通常の冷却運転時の制御である。
しかし、ステップS9で中間圧の冷媒を高圧側に逆流させることにより、冷凍サイクル内の冷媒の圧力状態が変化させたため、この圧力状態の変化に応じて、第一膨張弁42A,42Bの開度や圧縮機11の運転周波数が調整される。このため、例えば、冷媒の圧力状態が圧縮不良状態のまま、第一膨張弁42A,42Bの開度が安定していたとしても、圧力状態の変化に応じて、第一膨張弁42A,42Bの開度や圧縮機11の運転周波数が調整されることにより、冷媒の圧力状態を正常な状態に復帰させることができる。
Subsequently, the main controller 50 adjusts the opening degrees of the first expansion valves 42A and 42B via the case controllers 45A and 45B, and controls the operating frequency of the compressor 11 (step S10). The control in step S10 is control during normal cooling operation.
However, since the pressure state of the refrigerant in the refrigeration cycle is changed by causing the intermediate pressure refrigerant to flow back to the high pressure side in step S9, the opening degree of the first expansion valves 42A and 42B is changed according to the change in the pressure state. And the operating frequency of the compressor 11 is adjusted. For this reason, for example, even if the opening state of the first expansion valves 42A and 42B is stable while the pressure state of the refrigerant is in a poorly compressed state, the first expansion valves 42A and 42B The pressure state of the refrigerant can be returned to the normal state by adjusting the opening degree and the operating frequency of the compressor 11.

続いて、主制御装置50は、冷凍装置1が運転中であるか否かを判別する(ステップS11)。具体的には、圧縮機11がサーモオフに至ったか否か、もしくは、ユーザが運転停止を指示したか否かを判別する。この判別において、冷凍装置1が運転中の場合(ステップS11;Yes)には、処理をステップS2に戻し、上記ステップS2〜ステップS11の処理を繰り返し実行する。一方、冷凍装置1が運転中でない場合(ステップS11;No)には、運転を停止(ステップS12)し、処理を終了する。   Subsequently, main controller 50 determines whether or not refrigeration apparatus 1 is in operation (step S11). Specifically, it is determined whether or not the compressor 11 has been thermo-off, or whether or not the user has instructed to stop operation. In this determination, when the refrigeration apparatus 1 is in operation (step S11; Yes), the process returns to step S2, and the processes of steps S2 to S11 are repeated. On the other hand, when the refrigeration apparatus 1 is not in operation (step S11; No), the operation is stopped (step S12), and the process is terminated.

この第1実施形態によれば、ガスクーラー23から第一膨張弁42A,42Bへ向かう冷媒と、ガスクーラー23の出口側から分岐され、第二膨張弁34を介して減圧された分岐冷媒との間で熱交換を行う過冷却熱交換器24を備え、この過冷却熱交換器24を出た分岐冷媒を中間圧となる高段圧縮要素11Bの入口側に戻す構成とするとともに、中間圧及び高圧の各冷媒圧力に基づいて圧縮機11での冷媒の圧縮状態を判別し、この冷媒の圧縮状態が、高圧よりも中間圧が高い圧縮不良状態に至った場合、または当該圧縮不良状態に至ると予想される場合には、第二膨張弁34の開度を拡大し、中間圧の冷媒を高圧側に逆流させるため、冷凍サイクル内の冷媒の圧力状態を変化させることができる。このため、この圧力状態の変化に応じて、第一膨張弁42A,42Bの開度や圧縮機11の運転周波数が調整されことにより、上記した圧縮不良状態が早期に解消され、冷媒の圧力状態を正常な状態に復帰させることができる。従って、圧縮不良による圧縮機11の入力の増大を防止でき、冷凍装置1の安定かつ高効率な運転が可能となる。   According to the first embodiment, the refrigerant from the gas cooler 23 toward the first expansion valves 42 </ b> A and 42 </ b> B and the branched refrigerant branched from the outlet side of the gas cooler 23 and decompressed via the second expansion valve 34. A subcooling heat exchanger 24 that exchanges heat between them, and a configuration in which the branched refrigerant that has exited the supercooling heat exchanger 24 is returned to the inlet side of the high-stage compression element 11B that has an intermediate pressure. The compression state of the refrigerant in the compressor 11 is determined based on each high-pressure refrigerant pressure, and when the compression state of the refrigerant reaches a compression failure state where the intermediate pressure is higher than the high pressure, or the compression failure state is reached. In the case where it is predicted that the opening degree of the second expansion valve 34 is increased and the intermediate pressure refrigerant is caused to flow back to the high pressure side, the pressure state of the refrigerant in the refrigeration cycle can be changed. For this reason, the opening degree of the first expansion valves 42A and 42B and the operating frequency of the compressor 11 are adjusted in accordance with the change in the pressure state, so that the above-described compression failure state is quickly eliminated, and the pressure state of the refrigerant Can be returned to a normal state. Therefore, an increase in the input of the compressor 11 due to poor compression can be prevented, and the refrigeration apparatus 1 can be operated stably and efficiently.

(第2実施形態)
上記した第1実施形態では、過冷却熱交換器24の分岐配管33に設けられた第二膨張弁34と、この第二膨張弁34の開度調整する主制御装置50とが圧縮不良解消手段として動作する構成を説明したが、この第2実施形態では、ショーケースユニット5A,5Bに設けられた第一膨張弁42A,42B、ケース制御装置45A,45B及び主制御装置50が圧縮不良解消手段を構成する。他の構成は、第1実施形態に記載したものと同一であるため、説明を省略する。
この第2実施形態では、高圧圧力Phと中間圧力Pmとの差圧が所定の値よりも小さい場合には、主制御装置50は、ケース制御装置45A,45Bを介して、第一膨張弁42A,42Bの開度を縮小する。この制御は、通常の冷却運転時における第一膨張弁42A,42Bの制御動作に優先して実行されるため、圧縮機11の高段圧縮要素11Bの冷媒吐出温度に関わらず、当該第一膨張弁42A,42Bの開度が縮小される。
これによれば、第一膨張弁42A,42Bの開度を縮小することにより、高段圧縮要素11Bから吐出される高圧の冷媒圧力が高まるため、冷凍サイクル内の冷媒の圧力状態を変化させることができる。このため、この圧力状態の変化に応じて、その後、第一膨張弁42A,42Bの開度や圧縮機11の運転周波数が調整されことにより、上記した圧縮不良状態が早期に解消され、冷媒の圧力状態を正常な状態に復帰させることができる。従って、圧縮不良による圧縮機11の入力の増大を防止でき、冷凍装置1の安定かつ高効率な運転が可能となる。
(Second Embodiment)
In the first embodiment described above, the second expansion valve 34 provided in the branch pipe 33 of the supercooling heat exchanger 24 and the main controller 50 that adjusts the opening of the second expansion valve 34 include the compression failure elimination means. In the second embodiment, the first expansion valves 42A and 42B, the case control devices 45A and 45B, and the main control device 50 provided in the showcase units 5A and 5B are provided with compression failure elimination means. Configure. Other configurations are the same as those described in the first embodiment, and thus description thereof is omitted.
In the second embodiment, when the differential pressure between the high pressure Ph and the intermediate pressure Pm is smaller than a predetermined value, the main controller 50 causes the first expansion valve 42A to pass through the case controllers 45A and 45B. , 42B is reduced. Since this control is executed in preference to the control operation of the first expansion valves 42A and 42B during the normal cooling operation, the first expansion is performed regardless of the refrigerant discharge temperature of the high-stage compression element 11B of the compressor 11. The opening degree of the valves 42A and 42B is reduced.
According to this, since the high-pressure refrigerant pressure discharged from the high-stage compression element 11B is increased by reducing the opening degree of the first expansion valves 42A and 42B, the pressure state of the refrigerant in the refrigeration cycle is changed. Can do. For this reason, the opening degree of the first expansion valves 42A and 42B and the operating frequency of the compressor 11 are then adjusted according to the change in the pressure state, so that the above-described compression failure state is eliminated early, and the refrigerant The pressure state can be returned to the normal state. Therefore, an increase in the input of the compressor 11 due to poor compression can be prevented, and the refrigeration apparatus 1 can be operated stably and efficiently.

(第3実施形態)
この第3実施形態では、圧縮機11,11と、この圧縮機11,11の運転周波数を調整する主制御装置50とが圧縮不良解消手段を構成する。他の構成は、第1実施形態に記載したものと同一であるため、説明を省略する。
この第3実施形態では、高圧圧力Phと中間圧力Pmとの差圧が所定の値よりも小さい場合には、主制御装置50は、圧縮機11,11の運転周波数を所定の周波数(例えば5Hz)だけ低減する。
これによれば、圧縮機11の運転周波数を低減することにより、冷凍サイクル内の冷媒の圧縮状態が大きく変化するため、この圧力状態の変化に応じて、第一膨張弁42A,42Bの開度や圧縮機11の運転周波数が調整されことにより、上記した圧縮不良状態が早期に解消され、冷媒の圧力状態を正常な状態に復帰させることができる。従って、圧縮不良による圧縮機11の入力の増大を防止でき、冷凍装置1の安定かつ高効率な運転が可能となる。この場合、高圧圧力Phと中間圧力Pmとの差圧が所定の値よりも大きくなれば、主制御装置50は、ショーケースユニット5A、5Bの冷凍負荷に応じた周波数制御を実行する。
(Third embodiment)
In the third embodiment, the compressors 11 and 11 and the main controller 50 that adjusts the operating frequency of the compressors 11 and 11 constitute compression failure eliminating means. Other configurations are the same as those described in the first embodiment, and thus description thereof is omitted.
In the third embodiment, when the differential pressure between the high pressure Ph and the intermediate pressure Pm is smaller than a predetermined value, the main controller 50 sets the operating frequency of the compressors 11 and 11 to a predetermined frequency (for example, 5 Hz). ) Only reduced.
According to this, since the compression state of the refrigerant in the refrigeration cycle is greatly changed by reducing the operating frequency of the compressor 11, the opening degree of the first expansion valves 42A and 42B is changed according to the change in the pressure state. In addition, by adjusting the operating frequency of the compressor 11, the above-described compression failure state can be eliminated at an early stage, and the pressure state of the refrigerant can be returned to a normal state. Therefore, an increase in the input of the compressor 11 due to poor compression can be prevented, and the refrigeration apparatus 1 can be operated stably and efficiently. In this case, if the differential pressure between the high pressure Ph and the intermediate pressure Pm is greater than a predetermined value, the main controller 50 executes frequency control according to the refrigeration load of the showcase units 5A and 5B.

(第4実施形態)
図4は、第4実施形態にかかる冷凍装置の冷媒回路を示す回路構成図である。
この実施形態では、冷凍機ユニット63は、圧縮機11の低段圧縮要素11Aの入口側に連なる低圧吸入管13と高段圧縮要素11Bの入口側に連なる中間圧吸入管19とを連結する連結管65と、この連結管65に設けられる開閉弁66とを備え、この開閉弁66及び当該開閉弁66の動作を制御する主制御装置50が圧縮不良解消手段を構成する。他の構成は、第1実施形態に記載したものと同一であるため、同一の符号を付して説明を省略する。
この第4実施形態では、高圧圧力Phと中間圧力Pmとの差圧が所定の値よりも小さい場合には、主制御装置50は開閉弁66を開放し、連結管65を介して、低圧吸入管13と中間圧吸入管19とを連通させる。
これによれば、高段圧縮要素11Bの入口側と低段圧縮要素11Aの入口側との圧力差によって、中間圧吸入管19を流れる中間圧の冷媒が低圧吸入管13内に流入するため、この中間圧が低下することにより、圧縮不良状態が早期に解消される。さらに、開閉弁66を開放することにより、冷凍サイクル内の冷媒の圧縮状態が大きく変化するため、この圧力状態の変化に応じて、第一膨張弁42A,42Bの開度や圧縮機11の運転周波数が調整されて、冷媒の圧力状態を正常な状態に復帰させることができる。従って、圧縮不良による圧縮機11の入力の増大を防止でき、冷凍装置1の安定かつ高効率な運転が可能となる。
(Fourth embodiment)
FIG. 4 is a circuit configuration diagram showing a refrigerant circuit of the refrigeration apparatus according to the fourth embodiment.
In this embodiment, the refrigerator unit 63 connects the low-pressure suction pipe 13 connected to the inlet side of the low-stage compression element 11A of the compressor 11 and the intermediate-pressure suction pipe 19 connected to the inlet side of the high-stage compression element 11B. A main controller 50 that includes a pipe 65 and an on-off valve 66 provided on the connecting pipe 65 and controls the operation of the on-off valve 66 and the on-off valve 66 constitutes a compression failure elimination means. Since other configurations are the same as those described in the first embodiment, the same reference numerals are given and description thereof is omitted.
In the fourth embodiment, when the differential pressure between the high pressure Ph and the intermediate pressure Pm is smaller than a predetermined value, the main controller 50 opens the on-off valve 66 and the low pressure suction via the connecting pipe 65. The pipe 13 and the intermediate pressure suction pipe 19 are communicated with each other.
According to this, because the intermediate pressure refrigerant flowing through the intermediate pressure suction pipe 19 flows into the low pressure suction pipe 13 due to the pressure difference between the inlet side of the high stage compression element 11B and the inlet side of the low stage compression element 11A, By reducing the intermediate pressure, the compression failure state is eliminated at an early stage. Furthermore, since the compression state of the refrigerant in the refrigeration cycle is greatly changed by opening the on-off valve 66, the opening degree of the first expansion valves 42A and 42B and the operation of the compressor 11 are changed according to the change in the pressure state. The frequency is adjusted, and the pressure state of the refrigerant can be returned to the normal state. Therefore, an increase in the input of the compressor 11 due to poor compression can be prevented, and the refrigeration apparatus 1 can be operated stably and efficiently.

以上、本発明の一実施形態について説明したが、本発明はこれに限定されるものではなく、種々の変更実施が可能である。例えば、上記した第1乃至第4実施形態に記載された圧縮不良解消手段としての構成を適宜組み合わせて実行しても良い。
例えば、圧縮機11の運転周波数を低減しつつ、第二膨張弁34の開度を所定開度開くことにより、圧縮不良状態をより早期に解消することができ、より早く正常な冷却運転を実行することができる。
また、上記した第1乃至第4実施形態に記載された構成を実行しても、圧縮不良状態を解消できない場合には、圧縮機11,11の動作を停止しても良い。圧縮機11,11を停止することにより、冷凍装置1の低圧、中間圧及び高圧が均圧化されるため、再度運転した際には、圧縮不良な状態が解消されて起動することができる。
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to this, A various change implementation is possible. For example, the configuration as the compression failure elimination unit described in the first to fourth embodiments described above may be appropriately combined and executed.
For example, by reducing the operation frequency of the compressor 11 and opening the opening of the second expansion valve 34 by a predetermined opening, the compression failure state can be eliminated earlier, and normal cooling operation is executed earlier. can do.
Further, if the compression failure state cannot be resolved even if the configuration described in the first to fourth embodiments is executed, the operations of the compressors 11 and 11 may be stopped. By stopping the compressors 11 and 11, the low pressure, intermediate pressure and high pressure of the refrigeration apparatus 1 are equalized, so that when the operation is performed again, the state of poor compression can be resolved and the system can be started.

本実施形態に係る冷凍装置の冷媒回路を示す回路構成図である。It is a circuit block diagram which shows the refrigerant circuit of the freezing apparatus which concerns on this embodiment. 圧縮不良状態を解消する際の動作を示すフローチャートである。It is a flowchart which shows the operation | movement at the time of eliminating a compression failure state. 圧縮不良状態を解消する動作時の圧力変動を示す概略図である。It is the schematic which shows the pressure fluctuation at the time of the operation | movement which eliminates a compression failure state. 別の実施形態にかかる冷凍装置の冷媒回路を示す回路構成図である。It is a circuit block diagram which shows the refrigerant circuit of the freezing apparatus concerning another embodiment.

1 冷凍装置
3、63 冷凍機ユニット
5A、5B ショーケースユニット
11 圧縮機(圧縮不良解消手段)
11A 低段圧縮要素
11B 高段圧縮要素
13 低圧吸入管
14 アキュームレータ
17 中間圧吐出管
18 中間冷却器
19 中間圧吸入管
20 中間圧力センサー
21 高圧吐出管
22 オイルセパレータ
23 ガスクーラー
24 過冷却熱交換器
25 吐出圧力センサー
26 吐出温度センサー
33 分岐配管
34 第二膨張弁(第二絞り手段、圧縮不良解消手段)
35 入口温度センサー
36 出口温度センサー
42A、42B 第一膨張弁(第一絞り手段、圧縮不良解消手段)
43A ケース熱交換器
44A ケースファン
45A、45B ケース制御装置
50 主制御装置(圧縮不良解消手段)
65 連結管
66 開閉弁(圧縮不良解消手段)
DESCRIPTION OF SYMBOLS 1 Refrigeration equipment 3, 63 Refrigerator unit 5A, 5B Showcase unit 11 Compressor (compression failure elimination means)
11A Low stage compression element 11B High stage compression element 13 Low pressure suction pipe 14 Accumulator 17 Intermediate pressure discharge pipe 18 Intermediate cooler 19 Intermediate pressure suction pipe 20 Intermediate pressure sensor 21 High pressure discharge pipe 22 Oil separator 23 Gas cooler 24 Supercooling heat exchanger 25 Discharge pressure sensor 26 Discharge temperature sensor 33 Branch pipe 34 Second expansion valve (second throttle means, compression failure elimination means)
35 Inlet temperature sensor 36 Outlet temperature sensor 42A, 42B First expansion valve (first throttling means, compression failure eliminating means)
43A Case heat exchanger 44A Case fan 45A, 45B Case controller 50 Main controller (compression failure elimination means)
65 Connecting pipe 66 Open / close valve (compression failure elimination means)

Claims (5)

低段圧縮要素及び高段圧縮要素を備え、前記低段圧縮要素で圧縮された中間圧の冷媒を前記高段圧縮要素に導いて圧縮し、高圧の冷媒を放熱器に吐出する多段式の圧縮機を備え、前記放熱器に第一絞り手段及び蒸発器を順次接続して冷凍サイクルが構成される冷凍装置において、
前記中間圧及び前記高圧の各冷媒圧力に基づいて前記圧縮機での冷媒の圧縮状態を判別する判別手段を備え、この判別手段により、前記冷媒の圧縮状態が、前記高圧よりも前記中間圧が高い圧縮不良状態に至った場合、または当該圧縮不良状態に至ると予想される場合に、前記高圧が前記中間圧よりも高くなるように制御されて当該圧縮不良状態を解消する圧縮不良解消手段を備えることを特徴とする冷凍装置。
Multi-stage compression comprising a low-stage compression element and a high-stage compression element, the intermediate-pressure refrigerant compressed by the low-stage compression element is guided to the high-stage compression element and compressed, and the high-pressure refrigerant is discharged to a radiator In a refrigeration apparatus comprising a refrigeration cycle by sequentially connecting a first throttle means and an evaporator to the radiator,
And determining means for determining the compression state of the refrigerant in the compressor based on the intermediate pressure and the high-pressure refrigerant pressure, and the determination means determines that the intermediate pressure is higher than the high pressure. A compression failure eliminating means for controlling the high pressure to be higher than the intermediate pressure to eliminate the compression failure state when a high compression failure state is reached or when the compression failure state is expected. A refrigeration apparatus comprising the refrigeration apparatus.
前記放熱器から前記第一絞り手段へ向かう冷媒と、前記放熱器の出口側から分岐され、第二絞り手段を介して減圧された分岐冷媒との間で熱交換を行う熱交換器を備え、この熱交換器を出た分岐冷媒を中間圧となる前記高段圧縮要素の入口側に戻す構成とし、
前記圧縮不良解消手段は、前記第二絞り手段の絞り開度を拡大し、前記中間圧の冷媒を前記高圧側に逆流させることを特徴とする請求項1に記載の冷凍装置。
A heat exchanger for exchanging heat between the refrigerant from the radiator toward the first throttle means and the branched refrigerant branched from the outlet side of the radiator and decompressed via the second throttle means; The branched refrigerant that has exited the heat exchanger is configured to return to the inlet side of the high-stage compression element that has an intermediate pressure,
2. The refrigeration apparatus according to claim 1, wherein the compression failure elimination unit expands a throttle opening of the second throttle unit and causes the intermediate pressure refrigerant to flow backward to the high pressure side.
前記圧縮不良解消手段は、前記第一絞り手段の絞り開度を縮小し、前記高段圧縮要素から吐出される高圧の冷媒圧力を高めることを特徴とする請求項1または2に記載の冷凍装置。   3. The refrigeration apparatus according to claim 1, wherein the compression failure eliminating unit reduces a throttle opening of the first throttle unit and increases a high-pressure refrigerant pressure discharged from the high-stage compression element. . 前記低段側圧縮要素の入口側と前記高段側圧縮要素の入口側との間を連結する連結管と、この連結管に設けられる開閉弁とを備え、前記圧縮不良解消手段は、前記開閉弁を開放して、前記中間圧の冷媒を低圧側に流通させることを特徴とする請求項1乃至3のいずれかに記載の冷凍装置。   A connecting pipe that connects between the inlet side of the low-stage compression element and the inlet side of the high-stage compression element; and an on-off valve provided in the connecting pipe; The refrigeration apparatus according to any one of claims 1 to 3, wherein a valve is opened to allow the intermediate-pressure refrigerant to flow to the low-pressure side. 前記圧縮機は周波数可変型の圧縮機であり、前記圧縮不良解消手段は、当該圧縮機の運転周波数を低減して運転することを特徴とする請求項1乃至4のいずれかに記載の冷凍装置。   The refrigeration apparatus according to any one of claims 1 to 4, wherein the compressor is a variable frequency compressor, and the compression failure elimination means operates by reducing an operating frequency of the compressor. .
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JPH08296913A (en) * 1995-04-26 1996-11-12 Matsushita Refrig Co Ltd Multi-chamber air-conditioner
JP2004251492A (en) * 2003-02-18 2004-09-09 Sanyo Electric Co Ltd Refrigerant cycle device
JP2007147228A (en) * 2005-11-30 2007-06-14 Daikin Ind Ltd Refrigerating device
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