JP5871723B2 - Air conditioner and control method thereof - Google Patents

Air conditioner and control method thereof Download PDF

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JP5871723B2
JP5871723B2 JP2012133796A JP2012133796A JP5871723B2 JP 5871723 B2 JP5871723 B2 JP 5871723B2 JP 2012133796 A JP2012133796 A JP 2012133796A JP 2012133796 A JP2012133796 A JP 2012133796A JP 5871723 B2 JP5871723 B2 JP 5871723B2
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evaporator
natural circulation
refrigerant
condenser
side connection
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JP2013257086A (en
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横関 敦彦
敦彦 横関
康孝 吉田
康孝 吉田
松村 賢治
賢治 松村
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Hitachi Appliances Inc
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Description

本発明は、自然循環による冷凍サイクル運転機能を備えている空気調和機及びその制御方法に関し、特に、自然循環による冷凍サイクル運転と強制循環による冷凍サイクル運転を切替え運転可能なものに関する。   The present invention relates to an air conditioner having a refrigeration cycle operation function based on natural circulation and a control method thereof, and more particularly to an air conditioner capable of switching between a refrigeration cycle operation based on natural circulation and a refrigeration cycle operation based on forced circulation.

自然循環による冷凍サイクル運転(自然循環運転)と強制循環による冷凍サイクル運転(強制循環運転)を切替え運転可能な従来の空気調和機としては、特開平11−182895号公報(特許文献1)に記載されたものなどがある。このような空気調和機においては、蒸発器と、この蒸発器よりも高い位置に設置された凝縮器とを冷媒配管で接続することにより、冷媒を循環させて自然循環運転を行なうようにしている。この自然循環運転は、外気が室温より低い場合に使用され、圧縮機を動作させずに、冷媒のヘッド差(前記蒸発器と凝縮器のヘッド差)のみで冷媒を循環させるので、省電力運転が可能となる。   As a conventional air conditioner capable of switching operation between refrigeration cycle operation (natural circulation operation) by natural circulation and refrigeration cycle operation (forced circulation operation) by forced circulation, it is described in JP-A-11-182895 (Patent Document 1). There is something that was done. In such an air conditioner, a natural circulation operation is performed by circulating a refrigerant by connecting an evaporator and a condenser installed at a higher position than the evaporator with a refrigerant pipe. . This natural circulation operation is used when the outside air is lower than room temperature, and the refrigerant is circulated only by the refrigerant head difference (the difference between the evaporator and the condenser head) without operating the compressor. Is possible.

特許文献1に記載された空気調和機においては、圧縮機、凝縮器、膨張弁、前記凝縮器よりも下方に配置した蒸発器、この蒸発器と、前記圧縮機及び凝縮器に接続する回路接続手段(四方弁)、前記膨張弁をバイパスする膨張弁バイパス回路、凝縮器用ファン及び蒸発器用ファンとを備えている。そして、自然循環運転の際には、前記膨張弁バイパス回路を使用すると共に、前記回路接続手段により前記蒸発器と凝縮器を接続し、自然循環運転用の冷媒回路を構成する。また、強制循環運転の際には、前記膨張弁バイパス回路を閉止して冷媒が前記膨張弁に流れるようにすると共に、前記回路接続手段で前記蒸発器と圧縮機を接続し、強制循環運転用の冷媒回路を構成する。これにより、自然循環運転及び強制循環運転の両方の運転を可能にしている。   In the air conditioner described in Patent Document 1, a compressor, a condenser, an expansion valve, an evaporator disposed below the condenser, a circuit connection connected to the evaporator and the compressor and the condenser Means (four-way valve), an expansion valve bypass circuit for bypassing the expansion valve, a condenser fan and an evaporator fan. In the natural circulation operation, the expansion valve bypass circuit is used, and the evaporator and the condenser are connected by the circuit connecting means to constitute a refrigerant circuit for natural circulation operation. Further, during the forced circulation operation, the expansion valve bypass circuit is closed so that the refrigerant flows into the expansion valve, and the evaporator and the compressor are connected by the circuit connecting means, and the forced circulation operation is performed. The refrigerant circuit is configured. This enables both natural circulation operation and forced circulation operation.

また、この特許文献1のものでは、前記自然循環運転時には、室内温度を検知して前記凝縮器用ファンと前記蒸発器用ファンのうち少なくとも一方のファンの風量を制御することにより、ファン動力を削減すると共に室内温度の過剰な低下を防止するようにしている。   Also, in this Patent Document 1, during the natural circulation operation, the fan power is reduced by detecting the room temperature and controlling the air volume of at least one of the condenser fan and the evaporator fan. At the same time, an excessive decrease in the room temperature is prevented.

特開平11−182895号公報Japanese Patent Laid-Open No. 11-182895

上記特許文献1のものでは、ファン制御を行なうことにより、省電力化や室温を適正に制御するようにしているが、室内温度(室温)は外気温度だけではなく、室内に発生する内部負荷によっても影響を受ける為、能力制御のみを目的としてファン制御を実施した場合、冷凍サイクルの運転状態が不安定となって自然循環運転を継続できない場合がある。   In the thing of the said patent document 1, although it is trying to control power saving and room temperature appropriately by performing fan control, indoor temperature (room temperature) is not only outside temperature but internal load generated indoors. Therefore, when fan control is performed only for capacity control, the operation state of the refrigeration cycle may become unstable and natural circulation operation may not be continued.

例えば、外気温度が高い状態の場合で、内部負荷が小さい場合、能力を少なくしようとして凝縮器用ファンが低速に制御された場合、凝縮器出口の冷媒状態が気液二相状態になり、室外機と室内機を接続する液接続配管(液管)内に多量のガス冷媒が混入することにより、安定した液ヘッド差を発生できなくなり、自然循環運転(自然循環冷房運転)が停止してしまうことがある。   For example, when the outside air temperature is high and the internal load is small, when the condenser fan is controlled at a low speed to reduce the capacity, the refrigerant state at the outlet of the condenser becomes a gas-liquid two-phase state, and the outdoor unit When a large amount of gas refrigerant is mixed in the liquid connection pipe (liquid pipe) that connects the indoor unit and the indoor unit, a stable liquid head difference cannot be generated, and natural circulation operation (natural circulation cooling operation) stops. There is.

逆に、外気温度が低い状態の場合で、内部負荷が小さい場合には、凝縮器用ファンが低速に制御されるだけでは能力低減が不十分で、更に蒸発器用ファンも低速に制御される場合がある。この場合、蒸発器出口の冷媒状態が湿り状態となり、前記液接続配管の液ヘッド差を打ち消す方向のヘッド差が、室内機と室外機を接続するガス接続配管(ガス管)に作用することになり、安定した自然循環ができなくなり、この場合、自然循環運転が停止してしまう可能性が更に高くなる。   On the other hand, when the outside air temperature is low and the internal load is small, the capacity reduction is not sufficient just by controlling the condenser fan at low speed, and the evaporator fan may be controlled at low speed. is there. In this case, the refrigerant state at the evaporator outlet becomes a wet state, and the head difference in the direction that cancels the liquid head difference in the liquid connection pipe acts on the gas connection pipe (gas pipe) that connects the indoor unit and the outdoor unit. Therefore, the stable natural circulation cannot be performed, and in this case, the possibility that the natural circulation operation stops is further increased.

本発明の目的は、自然循環運転が停止した場合に、安定した自然循環運転へ再起動することのできる空気調和機及びその制御方法を得ることにある。   An object of the present invention is to obtain an air conditioner that can be restarted to a stable natural circulation operation and a control method thereof when the natural circulation operation is stopped.

上記目的を達成するための本発明は、蒸発器と、この蒸発器よりも高い位置に設置された凝縮器と、前記蒸発器と前記凝縮器を接続する液側接続配管及びガス側接続配管と、前記蒸発器の上流側に設けられた弁装置と、前記蒸発器に送風するための蒸発器用ファンと、前記凝縮器に送風するための凝縮器用ファンとを備え、自然循環による冷凍サイクル運転を行う空気調和機であって、自然循環による冷房運転時における冷却能力を検出して自然循環運転の停止有無を判定する自然循環運転の停止判定装置を備え、前記停止判定装置は、少なくとも前記蒸発器の吸込空気温度と吹出空気温度との差に基づいて自然循環運転の停止有無を判定し、自然循環による冷房運転時に自然循環運転が停止した場合、前記蒸発器上流側に設けられた弁装置を全閉にすると共に、前記蒸発器用ファン及び前記凝縮器用ファンを増速させて前記液側接続配管に液冷媒を増加させ、前記ガス側接続配管にはガス冷媒を増加させるように制御し、その後前記蒸発器上流側の弁装置を開放させて自然循環運転の再起動を行なうように制御する制御装置を備えることを特徴とする。 The present invention for achieving the above object includes an evaporator, a condenser installed at a position higher than the evaporator, a liquid side connection pipe and a gas side connection pipe connecting the evaporator and the condenser, A refrigeration cycle operation by natural circulation, comprising a valve device provided on the upstream side of the evaporator, an evaporator fan for sending air to the evaporator, and a condenser fan for sending air to the condenser An air conditioner for performing a natural circulation operation stop determination device that detects cooling capability during cooling operation by natural circulation and determines whether natural circulation operation is stopped, and the stop determination device includes at least the evaporator inlet air temperature and based on the difference between the outlet air temperature is determined to stop the presence or absence of natural circulation operation, if you stop the natural circulation operation to the cooling operation by natural circulation, the evaporator upstream valve device provided in the Fully closed, the evaporator fan and the condenser fan are accelerated to increase the liquid refrigerant in the liquid side connection pipe, and the gas side connection pipe is controlled to increase the gas refrigerant. A control device is provided that controls to open the valve device on the upstream side of the evaporator so as to restart the natural circulation operation.

本発明の他の特徴は、蒸発器と、この蒸発器よりも高い位置に設置された凝縮器と、前記蒸発器と前記凝縮器を接続する液側接続配管及びガス側接続配管と、前記蒸発器の上流側に設けられた弁装置と、前記蒸発器に送風するための蒸発器用ファンと、前記凝縮器に送風するための凝縮器用ファンとを備え、自然循環による冷凍サイクル運転を行う空気調和機の制御方法であって、少なくとも前記蒸発器の吸込空気温度と吹出空気温度との差に基づいて自然循環運転の停止有無を判定し、自然循環運転が停止した場合、前記蒸発器上流側に設けられた弁装置を全閉にすると共に、前記蒸発器用ファン及び前記凝縮器用ファンを増速させて前記液側接続配管に液冷媒を増加させ、前記ガス側接続配管にはガス冷媒を増加させるように制御し、その後前記蒸発器上流側の弁装置を開放させて自然循環運転の再起動を行なうことにある。 Other features of the present invention include an evaporator, a condenser installed at a higher position than the evaporator, a liquid side connection pipe and a gas side connection pipe connecting the evaporator and the condenser, and the evaporation. An air conditioner comprising a valve device provided upstream of the condenser, an evaporator fan for sending air to the evaporator, and a condenser fan for sending air to the condenser, and performing a refrigeration cycle operation by natural circulation And determining whether or not the natural circulation operation is stopped based on at least the difference between the intake air temperature and the blown air temperature of the evaporator, and when the natural circulation operation is stopped, on the upstream side of the evaporator The provided valve device is fully closed, the evaporator fan and the condenser fan are accelerated to increase the liquid refrigerant in the liquid side connection pipe, and the gas refrigerant is increased in the gas side connection pipe Control so that Opens the valve device of the rear said evaporator upstream in carrying out the restart of natural circulation operation by.

本発明によれば、自然循環運転が停止した場合に、安定した自然循環運転へ再起動することのできる空気調和機及びその制御方法を得ることができる効果がある。   ADVANTAGE OF THE INVENTION According to this invention, when a natural circulation driving | operation stops, there exists an effect which can obtain the air conditioner which can be restarted to the stable natural circulation driving | operation, and its control method.

本発明の空気調和機の実施例1を示す冷凍サイクル構成図。The refrigeration cycle block diagram which shows Example 1 of the air conditioner of this invention. 図1の空気調和機における自然循環運転時の理想的な状態を示すモリエル線図。The Mollier diagram which shows the ideal state at the time of the natural circulation driving | operation in the air conditioner of FIG. 図1の空気調和機における自然循環運転時の冷媒循環が滞り易い運転状態を示すモリエル線図。The Mollier diagram which shows the driving | running state which the refrigerant | coolant circulation at the time of the natural circulation driving | operation of the air conditioner of FIG. 1 tends to stagnate.

以下、本発明の空気調和機及びその制御方法の具体的実施例を図面に基づいて説明する。   Hereinafter, specific embodiments of the air conditioner and the control method thereof according to the present invention will be described with reference to the drawings.

本発明の空気調和機及びその制御方法の実施例1を図1〜図3により説明する。
図1は、本実施例における空気調和機の冷凍サイクル構成図である。図において、100は室外機、200は室内機である。前記室外機100は前記室内機200に対してH1(m)だけ高い位置に設置されている。
A first embodiment of an air conditioner and a control method thereof according to the present invention will be described with reference to FIGS.
FIG. 1 is a configuration diagram of a refrigeration cycle of an air conditioner in the present embodiment. In the figure, 100 is an outdoor unit, and 200 is an indoor unit. The outdoor unit 100 is installed at a position higher than the indoor unit 200 by H1 (m).

前記室外機100には、圧縮機1、四方弁2、冷房運転時に凝縮器となる室外熱交換器3、サブクーラ34、室外膨張弁4、液阻止弁60、ガス阻止弁61及びアキュムレータ9などが設けられている。また、前記室外熱交換器3にはその液側にディストリビュータ33が、そのガス側にはガス側ヘッダ36が設けられている。
前記室内機200には、室内膨張弁(弁装置)6及び冷房運転時に蒸発器となる室内熱交換器7などが設けられている。
The outdoor unit 100 includes a compressor 1, a four-way valve 2, an outdoor heat exchanger 3 that becomes a condenser during cooling operation, a subcooler 34, an outdoor expansion valve 4, a liquid blocking valve 60, a gas blocking valve 61, an accumulator 9, and the like. Is provided. The outdoor heat exchanger 3 is provided with a distributor 33 on the liquid side and a gas side header 36 on the gas side.
The indoor unit 200 is provided with an indoor expansion valve (valve device) 6 and an indoor heat exchanger 7 that serves as an evaporator during cooling operation.

5は前記室外機100の液阻止弁60側と前記室内機200の室内膨張弁6側とを接続している液側接続配管、8は前記室外機100のガス阻止弁61側と前記室内機200の室内熱交換器7側とを接続しているガス側接続配管である。
また、本実施例では、図1に示すように、前記液側接続配管5と前記室内機200とは、室内熱交換器7の高さ寸法Hhexに対し、その下部から上方に向って1/4までの高さ寸法範囲位置で接続されている。また、前記ガス側接続配管8と前記室内機200とは、室内熱交換器7の高さ寸法Hhexに対し、その上部から下方に向って1/4までの高さ寸法範囲位置で接続されている。このように前記液側接続配管5とガス側接続配管8を前記室内機200に接続する構成とすることにより、前記室外側熱交換器3からは前記液側接続配管5を介して前記室内熱交換器7側に液冷媒が流れ易くなり、また前記室内熱交換器7からは前記ガス側接続配管8を介して、前記室外熱交換器3側にガス冷媒が流れ易くなる。
5 is a liquid side connection pipe connecting the liquid blocking valve 60 side of the outdoor unit 100 and the indoor expansion valve 6 side of the indoor unit 200, and 8 is a gas blocking valve 61 side of the outdoor unit 100 and the indoor unit. 200 is a gas side connection pipe connecting the 200 indoor heat exchanger 7 side.
Further, in the present embodiment, as shown in FIG. 1, the liquid side connection pipe 5 and the indoor unit 200 have a height dimension Hhex of the indoor heat exchanger 7 1 / Connected at up to 4 height dimension range positions. Further, the gas side connection pipe 8 and the indoor unit 200 are connected to the height dimension Hhex of the indoor heat exchanger 7 at a height dimension range position up to 1/4 from the upper part to the lower side. Yes. In this way, by connecting the liquid side connection pipe 5 and the gas side connection pipe 8 to the indoor unit 200, the indoor heat is transmitted from the outdoor heat exchanger 3 through the liquid side connection pipe 5. The liquid refrigerant easily flows to the exchanger 7 side, and the gas refrigerant easily flows from the indoor heat exchanger 7 to the outdoor heat exchanger 3 side via the gas side connection pipe 8.

そして、前記圧縮機1、四方弁2、室外熱交換器3、サブクーラ34、室外膨張弁4、液阻止弁60、液側接続配管5、室内膨張弁6、室内熱交換器7、ガス側接続配管8、ガス阻止弁61、再び四方弁2、アキュムレータ9と経由して前記圧縮機1に再び接続されるように、これらの機器が冷媒配管で環状に接続されて強制循環による冷凍サイクル運転(強制循環運転)ができるようになっている。   And the said compressor 1, the four-way valve 2, the outdoor heat exchanger 3, the subcooler 34, the outdoor expansion valve 4, the liquid blocking valve 60, the liquid side connection piping 5, the indoor expansion valve 6, the indoor heat exchanger 7, the gas side connection These devices are connected to the compressor 1 via the piping 8, the gas blocking valve 61, the four-way valve 2, and the accumulator 9 again so that they are connected in a ring shape with refrigerant piping, and the refrigeration cycle operation by forced circulation ( Forced circulation operation).

また、本実施例では、前記ガス阻止弁61と前記室外熱交換器3のガス側とを接続するバイパス配管(第1のバイパス配管)20が設けられており、このバイパス配管20には第1の開閉弁21とバイパス逆止弁25が設けられている。更に、前記室外熱交換器3のガス側と前記四方弁2を接続する冷媒配管の途中には第2の開閉弁22が設けられ、前記ガス阻止弁61と前記四方弁2とを接続する冷媒配管の途中には第3の開閉弁23が設けられている。この第3開閉弁23と前記ガス阻止弁61との間に前記バイパス配管20の一端が接続され、このバイパス配管20の他端は、前記第2開閉弁22と前記室外熱交換器3のガス側ヘッダ36とを接続している冷媒配管35に接続されている。   In this embodiment, a bypass pipe (first bypass pipe) 20 that connects the gas blocking valve 61 and the gas side of the outdoor heat exchanger 3 is provided, and the bypass pipe 20 includes a first pipe. On-off valve 21 and bypass check valve 25 are provided. Furthermore, a second on-off valve 22 is provided in the middle of the refrigerant pipe connecting the gas side of the outdoor heat exchanger 3 and the four-way valve 2, and the refrigerant connecting the gas blocking valve 61 and the four-way valve 2. A third on-off valve 23 is provided in the middle of the piping. One end of the bypass pipe 20 is connected between the third on-off valve 23 and the gas blocking valve 61, and the other end of the bypass pipe 20 is connected to the gas of the second on-off valve 22 and the outdoor heat exchanger 3. The refrigerant pipe 35 is connected to the side header 36.

このように構成することにより、自然循環による冷凍サイクル運転(自然循環運転)も可能な構成となっている。即ち、前記第1の開閉弁21を開くと共に、前記第2及び第3の開閉弁22,23を閉じることにより、蒸発器(室内熱交換器7)からのガス冷媒を、前記圧縮機1には流さず、前記バイパス配管20を介して凝縮器(室外熱交換器3)に流すことにより、自然循環冷房運転が可能となる。従って、前記第1〜第3の各開閉弁21〜23は、強制循環運転と自然循環運転とを切り替える切替回路を構成している。 By comprising in this way, it becomes the structure which can also perform the refrigerating cycle driving | operation (natural circulation driving | operation) by natural circulation. That is, by opening the first on-off valve 21 and closing the second and third on-off valves 22, 23, the gas refrigerant from the evaporator (indoor heat exchanger 7) is supplied to the compressor 1. The natural circulation cooling operation can be performed by flowing to the condenser (outdoor heat exchanger 3) through the bypass pipe 20 without flowing. Accordingly, each of the first to third on-off valves 21 to 23 constitutes a switching circuit that switches between forced circulation operation and natural circulation operation.

更に、本実施例では、前記第3開閉弁23と前記ガス阻止弁61との間の冷媒配管(ガス側接続配管)と、前記室外膨張弁4と前記液阻止弁60との間の冷媒配管(液側接続配管)とを接続するバイパス配管(第2のバイパス配管)30を設け、このバイパス配管30には余剰冷媒を溜めるための冷媒貯留器10が設けられている。また、前記冷媒貯留器10の両側の前記バイパス配管30には、該バイパス配管30を開閉するためのガス側開閉弁26と液側開閉弁27が設けられている。
前記バイパス配管30は、前記室外熱交換器3と、前記室内熱交換器7を接続している前記液側接続配管5と前記ガス側接続配管8とを接続するように設けられていれば良く、好ましくは図1に示すように、室外機100内のガス側接続配管8側近傍(ガス阻止弁61付近)と液側接続配管5側近傍(液阻止弁付近)とを接続するように設けると良い。
Further, in this embodiment, a refrigerant pipe (gas side connection pipe) between the third on-off valve 23 and the gas blocking valve 61 and a refrigerant pipe between the outdoor expansion valve 4 and the liquid blocking valve 60 are provided. A bypass pipe (second bypass pipe) 30 for connecting (liquid side connection pipe) is provided, and the bypass pipe 30 is provided with a refrigerant reservoir 10 for storing surplus refrigerant. The bypass pipe 30 on both sides of the refrigerant reservoir 10 is provided with a gas side on / off valve 26 and a liquid side on / off valve 27 for opening and closing the bypass pipe 30.
The bypass pipe 30 may be provided so as to connect the outdoor heat exchanger 3, the liquid side connection pipe 5 connecting the indoor heat exchanger 7, and the gas side connection pipe 8. Preferably, as shown in FIG. 1, the vicinity of the gas side connection pipe 8 in the outdoor unit 100 (near the gas blocking valve 61) is connected to the vicinity of the liquid side connecting pipe 5 (near the liquid blocking valve). And good.

なお、図1において、24は圧縮機1への冷媒の逆流を防止するための吐出逆止弁である。また、40は前記圧縮機1の吐出側温度を検出するための吐出温度センサ、41は前記室外熱交換器3の液温度センサ、42は前記サブクーラ34出口の液冷媒の温度を検出するサブクーラ出口温度センサ、43は前記室内熱交換器7の液温度センサ、44は前記室内熱交換器7のガス温度センサ、45は前記室内熱交換器7に吸い込まれる室内空気の温度を検出する室内吸込温度センサ、46は前記室内熱交換器7で熱交換されて室内に吹き出された空気の温度を検出する室内吹出温度センサ、47は前記室外熱交換器3に吸い込まれる室外空気の温度を検出するための室外吸込温度センサ、48は前記圧縮機1から吐出される冷媒の圧力を検出する吐出圧力センサである。   In FIG. 1, reference numeral 24 denotes a discharge check valve for preventing the refrigerant from flowing backward to the compressor 1. 40 is a discharge temperature sensor for detecting the discharge side temperature of the compressor 1, 41 is a liquid temperature sensor for the outdoor heat exchanger 3, and 42 is a sub cooler outlet for detecting the temperature of the liquid refrigerant at the outlet of the sub cooler 34. The temperature sensor 43 is a liquid temperature sensor of the indoor heat exchanger 7, 44 is a gas temperature sensor of the indoor heat exchanger 7, and 45 is an indoor suction temperature for detecting the temperature of the indoor air sucked into the indoor heat exchanger 7. A sensor 46 detects the temperature of the air blown into the room after heat is exchanged by the indoor heat exchanger 7, and 47 detects the temperature of the outdoor air sucked into the outdoor heat exchanger 3. The outdoor suction temperature sensor 48 is a discharge pressure sensor for detecting the pressure of the refrigerant discharged from the compressor 1.

これらの各センサ40〜48からの検出データは前記室外機100や前記室内機200、或いはリモコンや遠隔監視装置(図示せず)などに設けられた制御装置70に送られ、この制御装置70は前記各センサなどからの情報に基づいて前記圧縮機1、四方弁(切替回路)2、室外膨張弁4、室内膨張弁6、前記各開閉弁21〜23,26,27,前記室外ファン50、前記室内ファン51などを制御するように構成されている。   Detection data from each of these sensors 40 to 48 is sent to the control unit 70 provided in the outdoor unit 100, the indoor unit 200, or a remote controller or a remote monitoring device (not shown). Based on information from the sensors, the compressor 1, a four-way valve (switching circuit) 2, an outdoor expansion valve 4, an indoor expansion valve 6, the on-off valves 21 to 23, 26, 27, the outdoor fan 50, The indoor fan 51 is controlled.

また、前記制御装置70はマイクロコンピュータなどにより構成され、各センサ40〜48からの入力された情報や、前記各制御対象1,2,4,6,21〜23,26,27,50,51の制御情報が記憶されるように構成されている。   Further, the control device 70 is constituted by a microcomputer or the like, and information inputted from the sensors 40 to 48 or the control objects 1, 2, 4, 6, 21 to 23, 26, 27, 50, 51. The control information is stored.

更に、前記制御装置70には、自然循環運転中に該自然循環運転が停止したことを判定する停止判定装置71が設けられている。この停止判定装置71は、例えば、自然循環冷房運転時における冷却能力を検出することで自然循環運転の停止有無を判定する。本実施例では、前記停止判定装置は、前記蒸発器の室内吸込温度センサ45で検出された吸込空気温度と、前記室内吹出温度センサ46で検出された吹出空気温度との差を求め、その差が所定値以下なら自然循環運転が停止していると判定するようにしている。この停止判定装置71は、前記凝縮器用ファン(室外送風機50)の回転数、前記蒸発器用ファン(室内送風機51)の回転数、前記室内膨張弁(弁装置)6の開度、前記室外吸込温度センサ47で検出された室外空気温度(凝縮器の吸込空気温度)、前記室内吸込温度センサ45で検出された室内空気温度(蒸発器の吸込空気温度)などの各情報の少なくとも1以上も加えて、自然循環運転の停止判定をするとなお好ましい。   Further, the control device 70 is provided with a stop determination device 71 for determining that the natural circulation operation is stopped during the natural circulation operation. The stop determination device 71 determines whether or not the natural circulation operation is stopped, for example, by detecting the cooling capacity during the natural circulation cooling operation. In this embodiment, the stop determination device obtains the difference between the intake air temperature detected by the indoor intake temperature sensor 45 of the evaporator and the blown air temperature detected by the indoor blowout temperature sensor 46, and the difference If is below a predetermined value, it is determined that the natural circulation operation is stopped. The stop determination device 71 includes a rotation speed of the condenser fan (outdoor fan 50), a rotation speed of the evaporator fan (indoor fan 51), an opening degree of the indoor expansion valve (valve device) 6, and the outdoor suction temperature. In addition to at least one of each information such as the outdoor air temperature detected by the sensor 47 (the intake air temperature of the condenser) and the indoor air temperature detected by the indoor intake temperature sensor 45 (the intake air temperature of the evaporator) Further, it is more preferable to determine whether to stop the natural circulation operation.

冷凍サイクル中には、所定量の冷媒が封入されており、例えばR410A、R407C、R404A、R134a、R32、R1234yf、R1234ze、R152a、R744、R717、R290、R600aなどの冷媒、またはこれらの混合物などが使用されている。冷媒の選定に当たっては、圧力損失が低く、蒸発潜熱が大きいものであれば、強制循環運転及び自然循環運転の効率を高くできるため、望ましい。   A predetermined amount of refrigerant is enclosed in the refrigeration cycle, for example, refrigerants such as R410A, R407C, R404A, R134a, R32, R1234yf, R1234ze, R152a, R744, R717, R290, R600a, or a mixture thereof. It is used. In selecting the refrigerant, it is desirable that the pressure loss is low and the latent heat of vaporization is large because the efficiency of forced circulation operation and natural circulation operation can be increased.

現在パッケージエアコン(業務用エアコン)やルームエアコンで広く使用されているR410Aは、電力消費を抑えて地球温暖化への間接影響を少なくすることができる。
また、蒸発潜熱が大きいR32を使用すれば、同一能力で運転する時の冷媒循環量を少なくすることができ、R410Aより低圧力損失になり、運転効率が向上するから、電力消費に伴って排出される二酸化炭素を少なくすることができる。加えてR32は、冷媒のGWP(地球温暖化係数)が小さいため、冷媒が大気中へ漏洩した際に生じる地球温暖化の直接影響を少なくすることが可能である。R32使用時の低圧力損失特性は、自然循環運転時のように、冷凍サイクルを駆動するための差圧が非常に小さい場合でも、安定した循環を維持することが容易であることから、自然循環運転と強制循環運転とを切り替えて使用するタイプの空気調和機用の冷媒として特に有効である。なお、前記冷媒として、R32だけでなく、R32の割合を50%以上(〜100%未満)とした冷媒を使用しても良い。
R410A, which is currently widely used in packaged air conditioners (commercial air conditioners) and room air conditioners, can reduce power consumption and reduce indirect effects on global warming.
In addition, if R32 with large latent heat of vaporization is used, the amount of refrigerant circulating when operating with the same capacity can be reduced, resulting in lower pressure loss than R410A and improved operating efficiency. Carbon dioxide can be reduced. In addition, since R32 has a small GWP (global warming potential) of the refrigerant, it is possible to reduce the direct influence of global warming that occurs when the refrigerant leaks into the atmosphere. The low pressure loss characteristic when using R32 is natural circulation because it is easy to maintain stable circulation even when the differential pressure for driving the refrigeration cycle is very small as in natural circulation operation. It is particularly effective as a refrigerant for a type of air conditioner that is used by switching between operation and forced circulation operation. In addition, you may use the refrigerant | coolant which made not only R32 but the ratio of R32 50% or more (-less than 100%) as said refrigerant | coolant.

圧縮機1を駆動させる強制循環運転時には、冷房運転、暖房運転共に、前記第1の開閉弁21を閉にすると共に、前記第2の開閉弁22と第3の開閉弁23は開に制御される。そして、強制循環冷房運転時には、圧縮機1の吐出側と室外熱交換器3のガス側が接続され、またアキュムレータ9とガス阻止弁61側が接続されるように前記四方弁2が切替えられる。これにより、圧縮機1で圧縮されて高温高圧となった冷媒は、四方弁2を通って前記室外熱交換器3に導かれ、室外送風機(凝縮器用ファン)50から送風される室外空気により冷却されて凝縮し、液冷媒となる。この液冷媒は、その後、全開状態に制御されている室外膨張弁4を通過して液阻止弁60、液側接続配管5を通り、前記室内機200へと送られる。   During the forced circulation operation for driving the compressor 1, the first on-off valve 21 is closed in both the cooling operation and the heating operation, and the second on-off valve 22 and the third on-off valve 23 are controlled to be opened. The In the forced circulation cooling operation, the four-way valve 2 is switched so that the discharge side of the compressor 1 and the gas side of the outdoor heat exchanger 3 are connected, and the accumulator 9 and the gas blocking valve 61 side are connected. As a result, the refrigerant which has been compressed by the compressor 1 and becomes high temperature and high pressure is led to the outdoor heat exchanger 3 through the four-way valve 2 and cooled by the outdoor air blown from the outdoor blower (condenser fan) 50. It is condensed and becomes a liquid refrigerant. Thereafter, the liquid refrigerant passes through the outdoor expansion valve 4 that is controlled to be fully opened, passes through the liquid blocking valve 60 and the liquid side connection pipe 5, and is sent to the indoor unit 200.

この室内機200に送られた前記液冷媒は、室内膨張弁(弁装置)6により所定量減圧されて、低圧の気液二相流となり、室内熱交換器(蒸発器)7に流入する。ここで、気液二相流の低圧冷媒は室内送風機(蒸発器用ファン)51からの室内空気と熱交換して蒸発し、低圧ガス冷媒になると共に、前記室内空気は冷却されることにより、冷房作用が為される。   The liquid refrigerant sent to the indoor unit 200 is depressurized by a predetermined amount by the indoor expansion valve (valve device) 6, becomes a low-pressure gas-liquid two-phase flow, and flows into the indoor heat exchanger (evaporator) 7. Here, the low-pressure refrigerant in the gas-liquid two-phase flow is evaporated by exchanging heat with the indoor air from the indoor blower (evaporator fan) 51 to become a low-pressure gas refrigerant, and the indoor air is cooled, thereby cooling. The action is made.

その後、前記低圧ガス冷媒は、前記ガス側接続配管8を通って前記室外機100へ戻り、ガス阻止弁61を通過後、四方弁2からアキュムレータ9へ流れて、圧縮機1へと吸い込まれる。   Thereafter, the low-pressure gas refrigerant returns to the outdoor unit 100 through the gas side connection pipe 8, passes through the gas blocking valve 61, flows from the four-way valve 2 to the accumulator 9, and is sucked into the compressor 1.

このように、空気調和機における強制循環冷房運転では、圧縮機1で冷媒を圧縮し、室外熱交換器3で凝縮させ、室内膨張弁6で減圧して、室内熱交換器7で蒸発させるという一連の冷凍サイクルを構成している。   As described above, in the forced circulation cooling operation in the air conditioner, the refrigerant is compressed by the compressor 1, condensed by the outdoor heat exchanger 3, decompressed by the indoor expansion valve 6, and evaporated by the indoor heat exchanger 7. It constitutes a series of refrigeration cycles.

強制循環暖房運転時には、前記四方弁2を、圧縮機1の吐出側とガス阻止弁61側とが、またアキュムレータ9と室外熱交換器3のガス側とが接続されるように切替える。冷凍サイクルの動作は、強制循環冷房運転時の場合に対して、室内熱交換器7が凝縮器として作用し、また室外熱交換器3は蒸発器として作用することになり、室内空気に対して暖房作用が為されることになる。即ち、冷凍サイクルの動作は逆になり、室内熱交換器7と室外熱交換器3の状態が逆転する。しかし、冷凍サイクルの原理は同一であるため、その他の詳細な説明は省略する。   During the forced circulation heating operation, the four-way valve 2 is switched so that the discharge side of the compressor 1 and the gas blocking valve 61 side are connected, and the accumulator 9 and the gas side of the outdoor heat exchanger 3 are connected. In the operation of the refrigeration cycle, the indoor heat exchanger 7 acts as a condenser and the outdoor heat exchanger 3 acts as an evaporator, compared with the case of forced circulation cooling operation. Heating action will be done. That is, the operation of the refrigeration cycle is reversed, and the states of the indoor heat exchanger 7 and the outdoor heat exchanger 3 are reversed. However, since the principle of the refrigeration cycle is the same, other detailed description is omitted.

次に、自然循環冷房運転時(自然循環運転)の動作について、図1の冷凍サイクル構成図及び図2のモリエル線図を用いて説明する。強制循環冷房運転から自然循環冷房運転に切り替える場合、前記制御装置70により、まず前記圧縮機1の運転を停止し、その後前記切替回路を構成する第1〜第3の開閉弁21〜23を操作して行う。即ち、第1の開閉弁21を開くと共に、第2の開閉弁22と第3の開閉弁23は閉じるように制御する。   Next, the operation during natural circulation cooling operation (natural circulation operation) will be described with reference to the refrigeration cycle configuration diagram of FIG. 1 and the Mollier diagram of FIG. When switching from forced circulation cooling operation to natural circulation cooling operation, the control device 70 first stops the operation of the compressor 1 and then operates the first to third on-off valves 21 to 23 constituting the switching circuit. And do it. That is, the first on-off valve 21 is opened, and the second on-off valve 22 and the third on-off valve 23 are controlled to close.

これにより、圧縮機1、四方弁2及びアキュムレータ9への冷媒循環は絶たれるため、不要な冷媒の溜まり込みが防止され、自然循環運転時の冷媒量が確保され易くなる。また、圧縮機1を再起動する際の液戻りによる液圧縮等を防止でき、信頼性低下に繋がるような不具合が発生するのも防止できる。   Thereby, since the refrigerant circulation to the compressor 1, the four-way valve 2 and the accumulator 9 is interrupted, unnecessary refrigerant accumulation is prevented, and the amount of refrigerant during natural circulation operation is easily secured. Further, liquid compression due to liquid return when the compressor 1 is restarted can be prevented, and it is possible to prevent a problem that leads to a decrease in reliability.

なお、自然循環運転が実施できるのは、前記室外吸込温度センサ47で検出された室外空気温度Toが前記室内吸込温度センサ45で検出された室内空気温度Tiよりも低い場合であり、例えば、次式が成立する場合に自然循環冷房運転を実施する。
To<Ti−10 (K)
この自然循環運転による冷媒の駆動力は、液冷媒とガス冷媒の密度差と、室外機と室内機間の設置高低差H1から生じるヘッド差ΔPであり、このヘッド差ΔPは次式で求めることができる。
ΔP=(ρ−ρ)・g・H1
ここで、ρは冷媒液密度(kg/m)、ρは冷媒ガス密度(kg/m)、gは重力加速度(m/s)、H1は室外機と室内機間の高低差(m)である。
The natural circulation operation can be performed when the outdoor air temperature To detected by the outdoor suction temperature sensor 47 is lower than the indoor air temperature Ti detected by the indoor suction temperature sensor 45. For example, If the equation is true, the natural circulation cooling operation is performed.
To <Ti-10 (K)
The driving force of the refrigerant by the natural circulation operation is the head difference ΔP generated from the density difference between the liquid refrigerant and the gas refrigerant and the installation height difference H1 between the outdoor unit and the indoor unit. This head difference ΔP is obtained by the following equation. Can do.
ΔP = (ρ L −ρ g ) · g · H1
Here, ρ L is the refrigerant liquid density (kg / m 3 ), ρ g is the refrigerant gas density (kg / m 3 ), g is the gravitational acceleration (m / s 2 ), and H1 is the height between the outdoor unit and the indoor unit. Difference (m).

即ち、図1に示した冷凍サイクル構成図において、室外熱交換器(凝縮器)3内の冷媒は、室外送風機(凝縮器用ファン)50により送風された室外空気(室内空気より低温)により、冷却されて凝縮し、液冷媒となって、前記ヘッド差ΔPにより、循環を開始する。   That is, in the refrigeration cycle configuration diagram shown in FIG. 1, the refrigerant in the outdoor heat exchanger (condenser) 3 is cooled by outdoor air (lower temperature than indoor air) blown by the outdoor blower (condenser fan) 50. Then, it is condensed and becomes a liquid refrigerant, and circulation is started by the head difference ΔP.

この自然循環運転では、室外膨張弁4は全開状態に制御されるので、前記室外熱交換器3からの液冷媒は前記室外膨張弁4をそのまま通過し、更に液阻止弁60を通過後、液側接続配管5を通って室内機200へ導かれる。   In this natural circulation operation, the outdoor expansion valve 4 is controlled to be fully opened, so that the liquid refrigerant from the outdoor heat exchanger 3 passes through the outdoor expansion valve 4 as it is, and further passes through the liquid blocking valve 60, It is guided to the indoor unit 200 through the side connection pipe 5.

この室内機200では、前記蒸発器としての室内熱交換器7の上流側に設けられているほぼ全開状態の室内膨張弁(弁装置)6を通過し、前記室内熱交換器(蒸発器)7に導入される。なお、室外機100と室内機200間の設置高低差H1が大きい場合には、前記室内膨張弁6の開度を調節して流量制御し、これにより冷却能力を制御する容量制御を実施する場合もある。   In this indoor unit 200, it passes through a substantially fully opened indoor expansion valve (valve device) 6 provided on the upstream side of the indoor heat exchanger 7 as the evaporator, and the indoor heat exchanger (evaporator) 7. To be introduced. When the installation height difference H1 between the outdoor unit 100 and the indoor unit 200 is large, the flow rate is controlled by adjusting the opening degree of the indoor expansion valve 6, thereby performing the capacity control for controlling the cooling capacity. There is also.

この容量制御においては、前記室内吸込温度センサ45で検出された前記蒸発器の吸込空気温度と、空調対象室内の設定空気温度との差に基づいて、まずは前記凝縮器用ファン(室外送風機)50を制御して行う。前記凝縮器用ファン50の制御だけでは容量制御が不十分の場合には、次に前記蒸発器用ファン(室内送風機)51の制御を行なう。これでもなお容量制御が不十分の場合には、前記蒸発器上流側の弁装置6の開度を制御して容量制御を行なう。このような順序で、必要に応じて、例えば、前記各ファン50,51を低速側へ、前記弁装置6を低開度側へ順に制御することで、低容量側への容量制御が可能となる。   In this capacity control, based on the difference between the intake air temperature of the evaporator detected by the indoor intake temperature sensor 45 and the set air temperature in the air-conditioning target room, the condenser fan (outdoor blower) 50 is first turned on. Control and do. If the capacity control is insufficient only by controlling the condenser fan 50, the evaporator fan (indoor fan) 51 is controlled next. If capacity control is still insufficient, capacity control is performed by controlling the opening degree of the valve device 6 on the upstream side of the evaporator. In this order, if necessary, for example, by controlling the fans 50 and 51 to the low speed side and the valve device 6 to the low opening side in order, capacity control to the low capacity side is possible. Become.

なお、本実施例では、前記蒸発器(室内熱交換器7)の上流に設けた弁装置6を室内膨張弁のみで構成している例で説明したが、前記弁装置6を、膨張弁と、これをバイパスするバイパス回路と、このバイパス回路を開閉する開閉弁で構成し、自然循環冷房運転時には、前記膨張弁を全閉とし、前記開閉弁を開いて前記パイパス回路を冷媒が通過するように構成しても良い。   In this embodiment, the example in which the valve device 6 provided upstream of the evaporator (indoor heat exchanger 7) is configured by only an indoor expansion valve has been described. However, the valve device 6 is an expansion valve. In the natural circulation cooling operation, the expansion valve is fully closed and the on-off valve is opened so that the refrigerant passes through the bypass circuit. You may comprise.

室内熱交換器7に流入した前記液冷媒は、室内送風機(蒸発器用ファン)51により送風される室内空気と熱交換して加熱され、蒸発してガス冷媒となる。この時前記室内空気は冷却されて室内を冷房する。   The liquid refrigerant that has flowed into the indoor heat exchanger 7 is heated by exchanging heat with the indoor air blown by the indoor blower (evaporator fan) 51 and evaporated to become a gas refrigerant. At this time, the room air is cooled to cool the room.

前記室内熱交換器7のガス冷媒は、ガス側接続配管8を通過して上昇し、上方に設置された前記室外機100に流入して、ガス阻止弁61を通過後、第1の開閉弁21、バイパス逆止弁25を通って、再び前記室外熱交換器(凝縮器)3へ戻るという一連の冷凍サイクルを構成する。   The gas refrigerant in the indoor heat exchanger 7 rises through the gas side connection pipe 8, flows into the outdoor unit 100 installed above, passes through the gas blocking valve 61, and then passes through the first on-off valve. 21, a series of refrigeration cycles in which the air passes through the bypass check valve 25 and returns to the outdoor heat exchanger (condenser) 3 again.

ここで、図2のモリエル線図上に自然循環運転時の運転状態を示すと、a→bは室外熱交換器(凝縮器)3での凝縮作用を、b→cは室外機100から室内機200への液冷媒の下降により液ヘッド差ΔPLが増大し、圧力が上昇している様子を示している。前記液ヘッド差ΔPLは、
ΔPL=ρ・g・H1
で求めることができる。なお、図2のb→cは、液側接続配管5の圧損ΔPLpipe分も考慮されている。また、Δhは前記蒸発器及び凝縮器における比エンタルピ差、Grは通常の自然循環運転時の冷媒循環量、SCcoは凝縮器出口過冷却度、SHeoは蒸発器出口過熱度である。
Here, when the operation state at the time of natural circulation operation is shown on the Mollier diagram of FIG. 2, a → b represents the condensation action in the outdoor heat exchanger (condenser) 3, and b → c represents the outdoor unit 100 to the indoor unit. The liquid head difference ΔPL is increased by the descending liquid refrigerant to the machine 200, and the pressure is increased. The liquid head difference ΔPL is:
ΔPL = ρ L · g · H1
Can be obtained. Note that b → c in FIG. 2 also takes into account the pressure loss ΔPLpipe of the liquid side connection pipe 5. Δh is a specific enthalpy difference between the evaporator and the condenser, Gr is a refrigerant circulation amount during normal natural circulation operation, SCco is a condenser outlet supercooling degree, and SHeo is an evaporator outlet superheat degree.

次に、c→dは室内熱交換器(蒸発器)7での蒸発作用を、d→aは室内機200から室外機100へのガス冷媒の上昇によるガス側接続配管8での圧力損失ΔPgpipeとガスヘッド差ΔPg(=ρ・g・H1)により圧力が低下している様子を示している。このように、冷媒がa→b→c→d→aと自然循環することにより、自然循環運転の冷凍サイクルを構成している。 Next, c → d is the evaporation effect in the indoor heat exchanger (evaporator) 7, and d → a is the pressure loss ΔPgpipe in the gas side connection pipe 8 due to the rise of the gas refrigerant from the indoor unit 200 to the outdoor unit 100. And a pressure drop due to the gas head difference ΔPg (= ρ g · g · H1). In this way, the refrigerant naturally circulates from a → b → c → d → a to constitute a refrigeration cycle for natural circulation operation.

これに対し、図3のモリエル線図上に示したのは、凝縮器用ファン(室外送風機50)と蒸発器用ファン(室内送風機51)の回転数を抑えた場合の自然循環冷房の運転状態である。凝縮器用ファンの回転数を低速に制御すると、凝縮器(室外熱交換器3)での冷媒状態はa´→b´と比エンタルピ差Δh´へと小さくなり、凝縮器出口状態は液冷媒にガス冷媒が混入した気液二相状態となる。また、蒸発器用ファンを低速に制御すると、蒸発器での冷媒状態はc´→d´となり、蒸発器出口ではガス冷媒に液冷媒が混入した気液二相状態になる。   On the other hand, what is shown on the Mollier diagram of FIG. 3 is an operating state of natural circulation cooling when the rotational speeds of the condenser fan (outdoor fan 50) and the evaporator fan (indoor fan 51) are suppressed. . When the rotational speed of the condenser fan is controlled to be low, the refrigerant state in the condenser (outdoor heat exchanger 3) decreases from a ′ → b ′ and the specific enthalpy difference Δh ′, and the condenser outlet state becomes liquid refrigerant. It becomes a gas-liquid two-phase state mixed with gas refrigerant. Further, when the evaporator fan is controlled at a low speed, the refrigerant state in the evaporator is c ′ → d ′, and at the outlet of the evaporator, a gas-liquid two-phase state in which the liquid refrigerant is mixed into the gas refrigerant is obtained.

凝縮器(室外熱交換器3)出口状態が気液二相状態になると、凝縮器から蒸発器(室内熱交換器7)へと冷媒が下降する液側接続配管内も気液二相状態となり、液側冷媒の液ヘッド差ΔPL´は、
ΔPL´=ρ´・g・H1
となる。ここで、液側接続配管5内の平均冷媒密度ρ´(kg/m)はガス冷媒の混入により、満液状態で運転された場合に比べて小さくなるため、液側接続配管5内のヘッドが減少する。
When the outlet state of the condenser (outdoor heat exchanger 3) is in a gas-liquid two-phase state, the liquid-side connection pipe in which the refrigerant descends from the condenser to the evaporator (indoor heat exchanger 7) is also in the gas-liquid two-phase state. The liquid head difference ΔPL ′ of the liquid side refrigerant is
ΔPL ′ = ρ L ′ · g · H1
It becomes. Here, the average refrigerant density ρ L ′ (kg / m 3 ) in the liquid side connection pipe 5 is smaller than that in the liquid side connection pipe 5 due to the mixing of the gas refrigerant. The head is reduced.

また、蒸発器出口状態が気液二相状態になると、蒸発器から凝縮器へと冷媒が上昇するガス側接続配管8内も気液二相状態になり、ガス側冷媒のガスヘッド差ΔPg´は、
ΔPg´=ρ´・g・H1
となる。ガス側接続配管8内冷媒の平均冷媒密度ρ´(kg/m)は液冷媒の混入により、ガスのみで運転された場合に比べて大きくなるため、ガス側接続配管8内のヘッドが増加して、冷媒循環を妨げる方向の力が作用する。
When the evaporator outlet state becomes a gas-liquid two-phase state, the gas-side connection pipe 8 in which the refrigerant rises from the evaporator to the condenser also becomes a gas-liquid two-phase state, and the gas head difference ΔPg ′ of the gas-side refrigerant. Is
ΔPg ′ = ρ g ′ · g · H1
It becomes. Since the average refrigerant density ρ L ′ (kg / m 3 ) of the refrigerant in the gas side connection pipe 8 becomes larger than that in the case of operating with only gas due to the mixture of liquid refrigerant, the head in the gas side connection pipe 8 is The force increases in the direction that hinders refrigerant circulation.

更に、前記各接続配管5,8内をそれぞれ液冷媒のみ、或いはガス冷媒のみが循環した場合に比べ、冷媒が気液二相状態で流れた場合の前記各接続配管内の圧力損失は増大する。従って、図3に示した自然循環冷房運転時の冷媒循環量Gr´は、図2に示した通常の自然循環運転時の冷媒循環量Grよりも減少し、前記蒸発器及び凝縮器における比エンタルピ差も図3に示したΔh´のように減少するから、これらの相乗効果により冷房能力Q´は、
Q´=Gr´・Δh´
へと減少する。これにより、室内の冷房負荷に応じて、冷房能力を調整することが可能である。
Further, the pressure loss in each of the connection pipes when the refrigerant flows in a gas-liquid two-phase state increases as compared with the case where only the liquid refrigerant or only the gas refrigerant circulates in each of the connection pipes 5 and 8. . Accordingly, the refrigerant circulation amount Gr ′ during the natural circulation cooling operation shown in FIG. 3 is smaller than the refrigerant circulation amount Gr during the normal natural circulation operation shown in FIG. 2, and the specific enthalpy in the evaporator and the condenser is reduced. Since the difference also decreases as Δh ′ shown in FIG. 3, the cooling capacity Q ′ is
Q ′ = Gr ′ · Δh ′
It decreases to. Thereby, it is possible to adjust the cooling capacity according to the cooling load in the room.

しかしながら、空調を行っている室内温度を調整するために、前記凝縮器用ファンと蒸発器用ファンの回転数を低下させる制御を実施した場合、前述したように、液側接続配管5へのガス冷媒の混入や、ガス側接続配管8への液冷媒の混入により、液側接続配管5での下降流、ガス側接続配管8での上昇流が阻害されることがある。
例えば、冷媒循環量Gr´が少なくなることにより、液側接続配管5内のガス冷媒が蒸発器側に下降することができなくなったり、ガス側接続配管8内の液冷媒が凝縮器側に上昇することができなくなることがある。このため冷媒循環が意図せずに停止して自然循環運転ができなくなることがあった。
However, when control is performed to reduce the rotational speed of the condenser fan and the evaporator fan in order to adjust the temperature of the air-conditioned room, as described above, the gas refrigerant to the liquid side connection pipe 5 Due to mixing or mixing of the liquid refrigerant into the gas side connection pipe 8, the downward flow in the liquid side connection pipe 5 and the upward flow in the gas side connection pipe 8 may be hindered.
For example, when the refrigerant circulation amount Gr ′ decreases, the gas refrigerant in the liquid side connection pipe 5 cannot fall to the evaporator side, or the liquid refrigerant in the gas side connection pipe 8 rises to the condenser side. You may not be able to. For this reason, refrigerant circulation may stop unintentionally and natural circulation operation may not be possible.

自然循環冷房運転が停止すると、冷房能力が発揮できなくなり、空調を行っている室内の温度上昇をもたらし、対人空調として使用している場合には居住者に対する快適性を損ね、電算機などの機器の空調として使用していた場合には、機器の安定運転を損ねるといった問題が生じる。   When the natural circulation cooling operation stops, the cooling capacity cannot be exhibited, the temperature inside the air-conditioned room rises, and if it is used for interpersonal air conditioning, the comfort for residents is impaired, such as a computer When used as an air conditioner, there arises a problem that the stable operation of the device is impaired.

そこで、本実施例の空気調和機では、自然循環運転中に、前記蒸発器における吸込空気温度と吹出空気温度の温度差が、予め定めた所定時間以上ゼロになっている場合には、自然循環運転が停止している判断し、次に説明する自然循環再起動制御へと移行させる。   Therefore, in the air conditioner of this embodiment, during the natural circulation operation, if the temperature difference between the intake air temperature and the blown air temperature in the evaporator is zero for a predetermined time or more, natural circulation is performed. It is determined that the operation has stopped, and the process proceeds to the natural circulation restart control described below.

自然循環再起動制御では、まず、蒸発器(室内熱交換器7)の上流側(自然循環運転時における上流側)に設置された前記室内膨張弁(弁装置)6を閉止すると共に、前記凝縮器用ファン(室外送風機50)、前記蒸発器用ファン(室内送風機51)を増速して運転する。これにより、前記凝縮器(室外熱交換器3)内には液冷媒が貯められていき、前記蒸発器内では冷媒がガス化してガス冷媒が増えていくので液冷媒は減少していく。   In the natural circulation restart control, first, the indoor expansion valve (valve device) 6 installed on the upstream side (upstream side during natural circulation operation) of the evaporator (indoor heat exchanger 7) is closed and the condensation is performed. The fan (outdoor fan 50) and the evaporator fan (indoor fan 51) are operated at an increased speed. As a result, liquid refrigerant is stored in the condenser (outdoor heat exchanger 3), and the refrigerant is gasified and gas refrigerant increases in the evaporator, so the liquid refrigerant decreases.

また、本実施例では、図1で説明したように、凝縮器と蒸発器を接続している液側接続配管を、前記蒸発器(室内熱交換器7)の高さ寸法Hhexに対し、該蒸発器下部から上方に向って1/4までの高さ寸法範囲位置で前記蒸発器に接続すると共に、前記ガス側接続配管8を、前記蒸発器の高さ寸法Hhexに対し、該蒸発器上部から下方に向って1/4までの高さ寸法範囲位置で前記蒸発器に接続しているので、前記凝縮器から前記液側接続配管5側に液冷媒が流れ易くなり、その結果、前記液側接続配管5内は液冷媒で満たされる状態となる。一方、前記ガス側接続配管8内はガス冷媒で満たされるように状態変化していく。   Further, in this embodiment, as described with reference to FIG. 1, the liquid side connection pipe connecting the condenser and the evaporator is connected to the height dimension Hhex of the evaporator (indoor heat exchanger 7). Connected to the evaporator at a height dimension range up to 1/4 from the lower part of the evaporator, and the gas side connection pipe 8 is connected to the upper part of the evaporator with respect to the height dimension Hhex of the evaporator. From the condenser to the liquid side connection pipe 5 side, and as a result, the liquid refrigerant can easily flow from the condenser to the liquid side connection pipe 5 side. The side connection pipe 5 is filled with the liquid refrigerant. On the other hand, the state of the gas side connection pipe 8 changes so as to be filled with the gas refrigerant.

このように、前記液側接続配管5は液冷媒で、前記ガス側接続配管8はガス冷媒で満たされるように状態変化していくことにより、自然循環運転を再起動するための十分なヘッド差が作用するようになる。上述したような制御状態を一定時間保持した後、前記室内膨張弁(弁)6を開放することにより、自然循環運転を再起動させることができる。   Thus, by changing the state so that the liquid side connection pipe 5 is filled with liquid refrigerant and the gas side connection pipe 8 is filled with gas refrigerant, a sufficient head difference for restarting the natural circulation operation is obtained. Comes to work. The natural circulation operation can be restarted by opening the indoor expansion valve (valve) 6 after holding the control state as described above for a certain period of time.

更に、自然循環運転の再起動を容易にする為には、液側接続配管5を凝縮器3から蒸発器7に至るまでの経路を下降のみで構成して、途中に逆勾配となる部分(トラップとなる部分)が生じないようにすることで、液側接続配管5へのガス冷媒の溜まり込みを防止することが可能となり、より再起動し易くなる効果が得られる。また、好ましくは、蒸発器7から凝縮器3までのガス側接続配管8の経路を上昇のみで構成して、途中に逆勾配となる部分(トラップとなる部分)が生じないようにすることで、このガス側接続配管8途中に液冷媒が溜まり込むのを防止することができ、更に再起動がし易くなる。   Furthermore, in order to facilitate the restart of the natural circulation operation, the liquid side connection pipe 5 is configured only by descending the path from the condenser 3 to the evaporator 7, and a part having a reverse gradient in the middle ( By preventing the occurrence of a trap portion), it is possible to prevent the gas refrigerant from accumulating in the liquid side connection pipe 5, and the effect of facilitating restart can be obtained. Preferably, the path of the gas side connection pipe 8 from the evaporator 7 to the condenser 3 is configured only by ascending so that a portion having a reverse gradient (a portion serving as a trap) does not occur in the middle. The liquid refrigerant can be prevented from accumulating in the middle of the gas side connection pipe 8 and can be easily restarted.

上記した自然循環の再起動制御を行った後において、再度冷房能力の発生が検知できない場合、つまり、前記室内吹出温度センサ46で検出される蒸発器7からの吹出空気温度が、前記室内吸込温度センサ45で検出される蒸発器7への吸込空気温度よりも低くならない状態が一定時間以上継続したした場合には、前記制御装置70は、強制循環冷房運転への切替え制御を行なう。即ち、前記制御装置70は、前記切替回路を構成している第1〜第3の開閉弁21〜23を強制循環冷房運転可能に切り替えると共に、前記圧縮機1を起動するように制御する。   After the above-described natural circulation restart control is performed, if the generation of the cooling capacity cannot be detected again, that is, the temperature of the air blown from the evaporator 7 detected by the indoor air temperature sensor 46 is the indoor air intake temperature. When the state in which the temperature does not become lower than the intake air temperature to the evaporator 7 detected by the sensor 45 continues for a certain time or longer, the control device 70 performs control to switch to the forced circulation cooling operation. That is, the control device 70 switches the first to third on-off valves 21 to 23 constituting the switching circuit to enable the forced circulation cooling operation, and controls the compressor 1 to start.

更に詳しく説明すれば、前記第1の開閉弁21を閉にすると共に、前記第2の開閉弁22と第3の開閉弁23を開に制御する。その後、圧縮機1が起動され、該圧縮機1により圧縮されて高温高圧となった冷媒は、四方弁2を通って前記室外熱交換器3に導かれ、室外送風機50から送風される室外空気により冷却されて凝縮し、液冷媒となる。この液冷媒は、その後、全開状態に制御されている室外膨張弁4を通過し、更に前記液阻止弁60、液側接続配管5を通って前記室内機200へと送られる。   More specifically, the first on-off valve 21 is closed, and the second on-off valve 22 and the third on-off valve 23 are controlled to be opened. Thereafter, the compressor 1 is started, and the refrigerant that has been compressed by the compressor 1 to high temperature and high pressure is led to the outdoor heat exchanger 3 through the four-way valve 2 and is blown from the outdoor blower 50. It is cooled and condensed by the above, and becomes a liquid refrigerant. Thereafter, the liquid refrigerant passes through the outdoor expansion valve 4 that is controlled to be fully opened, and is further sent to the indoor unit 200 through the liquid blocking valve 60 and the liquid side connection pipe 5.

この室内機200に送られた前記液冷媒は、前記室内膨張弁6により所定量減圧されて、低圧の気液二相流となり、室内熱交換器7に流入する。ここで、気液二相流の低圧冷媒は室内送風機51からの室内空気と熱交換して蒸発し、自らは低圧ガス冷媒になると共に前記室内空気を冷却し、冷房作用が為される。   The liquid refrigerant sent to the indoor unit 200 is decompressed by a predetermined amount by the indoor expansion valve 6, becomes a low-pressure gas-liquid two-phase flow, and flows into the indoor heat exchanger 7. Here, the gas-liquid two-phase low-pressure refrigerant evaporates by exchanging heat with the room air from the indoor blower 51, and becomes a low-pressure gas refrigerant and cools the room air, thereby performing a cooling operation.

その後、前記低圧ガス冷媒は、前記ガス側接続配管8を通って室外機100へ戻り、ガス阻止弁61を通過後、四方弁2からアキュムレータ9へ流れて、前記圧縮機1に再び吸い込まれるという強制循環冷房運転が行われる。   Thereafter, the low-pressure gas refrigerant returns to the outdoor unit 100 through the gas-side connection pipe 8, passes through the gas blocking valve 61, flows from the four-way valve 2 to the accumulator 9, and is sucked into the compressor 1 again. Forced circulation cooling operation is performed.

このように、強制循環冷房運転を一定時間行うことにより、前記液側接続配管5は液冷媒で満たされ、前記ガス側接続配管8はガス冷媒で満たされる状態になる。このため、その後の自然循環運転への切り替えを確実に行うことができる。   In this way, by performing the forced circulation cooling operation for a certain time, the liquid side connection pipe 5 is filled with the liquid refrigerant, and the gas side connection pipe 8 is filled with the gas refrigerant. For this reason, switching to the subsequent natural circulation operation can be performed reliably.

本実施例によれば、自然循環運転において、前記液側接続配管5やガス側接続配管8内の冷媒状態が理想的な状態とならずに、自然循環運転が停止した場合でも、安定した自然循環運転への再起動を速やかに行なわせることのできる空気調和機を得ることができる。
また、本実施例によれば、自然循環運転が不意に停止すると、その停止状態を速やかに且つ正確に判定して、安定した自然循環運転へ速やかに再起動できるから、無駄な電力消費を押さえることが可能になると共に、空調する室内温度の上昇による快適性への悪影響も低減できる。
According to the present embodiment, in natural circulation operation, the refrigerant state in the liquid side connection pipe 5 and the gas side connection pipe 8 is not ideal, and even if natural circulation operation is stopped, stable natural An air conditioner capable of promptly restarting the circulation operation can be obtained.
Further, according to the present embodiment, when the natural circulation operation is stopped unexpectedly, the stop state can be determined promptly and accurately, and the system can be promptly restarted to a stable natural circulation operation, so that unnecessary power consumption is suppressed. In addition, it is possible to reduce adverse effects on comfort due to an increase in the temperature of the air-conditioned room.

1…圧縮機、2…四方弁、3…室外熱交換器(凝縮器)、4…室外膨張弁、
5…液側接続配管、6…室内膨張弁(弁装置)、7…室内熱交換器(蒸発器)、
8…ガス側接続配管、9…アキュムレータ、10…冷媒貯留器、
20…バイパス配管(第1のバイパス配管)、
21〜23…切替回路(21…第1の開閉弁、22…第2の開閉弁、
23…第3の開閉弁、)
24…吐出逆止弁、25…バイパス逆止弁、
26…ガス側開閉弁、27…液側開閉弁、
30…バイパス配管(第2のバイパス配管)、
33…ディストリビュータ、34…サブクーラ、
36…ガス側ヘッダ、40…吐出温度センサ、
41,43…液温度センサ、42…サブクーラ出口温度センサ、
44…ガス温度センサ、
45…室内吸込温度センサ、46…室内吐出温度センサ、
47…室外吸込温度センサ、48…吐出圧力検知手段、
50…室外送風機(凝縮器用ファン)、51…室内送風機(蒸発器用ファン)、
60…液阻止弁、61…ガス阻止弁、
70…制御装置、71…停止判定装置、
100…室外機、200…室内機。
DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Four-way valve, 3 ... Outdoor heat exchanger (condenser), 4 ... Outdoor expansion valve,
5 ... Liquid side connection piping, 6 ... Indoor expansion valve (valve device), 7 ... Indoor heat exchanger (evaporator),
8 ... Gas side connection piping, 9 ... Accumulator, 10 ... Refrigerant reservoir,
20: Bypass piping (first bypass piping),
21-23 ... switching circuit (21 ... 1st on-off valve, 22 ... 2nd on-off valve,
23 ... Third on-off valve)
24 ... discharge check valve, 25 ... bypass check valve,
26 ... Gas side on / off valve, 27 ... Liquid side on / off valve,
30: Bypass piping (second bypass piping),
33 ... Distributor, 34 ... Subcooler,
36 ... Gas side header, 40 ... Discharge temperature sensor,
41, 43 ... liquid temperature sensor, 42 ... subcooler outlet temperature sensor,
44 ... gas temperature sensor,
45 ... Indoor suction temperature sensor, 46 ... Indoor discharge temperature sensor,
47 ... outdoor suction temperature sensor, 48 ... discharge pressure detection means,
50 ... Outdoor fan (condenser fan), 51 ... Indoor fan (evaporator fan),
60 ... Liquid blocking valve, 61 ... Gas blocking valve,
70 ... Control device, 71 ... Stop determination device,
100: outdoor unit, 200: indoor unit.

Claims (9)

蒸発器と、この蒸発器よりも高い位置に設置された凝縮器と、前記蒸発器と前記凝縮器を接続する液側接続配管及びガス側接続配管と、前記蒸発器の上流側に設けられた弁装置と、前記蒸発器に送風するための蒸発器用ファンと、前記凝縮器に送風するための凝縮器用ファンとを備え、自然循環による冷凍サイクル運転を行う空気調和機であって、
自然循環による冷房運転時における冷却能力を検出して自然循環運転の停止有無を判定する自然循環運転の停止判定装置を備え、前記停止判定装置は、少なくとも前記蒸発器の吸込空気温度と吹出空気温度との差に基づいて自然循環運転の停止有無を判定し、
自然循環による冷房運転時に自然循環運転が停止した場合、前記蒸発器上流側に設けられた弁装置を全閉にすると共に、前記蒸発器用ファン及び前記凝縮器用ファンを増速させて前記液側接続配管に液冷媒を増加させ、前記ガス側接続配管にはガス冷媒を増加させるように制御し、その後前記蒸発器上流側の弁装置を開放させて自然循環運転の再起動を行なうように制御する制御装置を備える
ことを特徴とする空気調和機。
An evaporator, a condenser installed at a position higher than the evaporator, a liquid side connection pipe and a gas side connection pipe connecting the evaporator and the condenser, and an upstream side of the evaporator. An air conditioner comprising a valve device, an evaporator fan for blowing air to the evaporator, and a condenser fan for blowing air to the condenser, and performing a refrigeration cycle operation by natural circulation,
A natural circulation operation stop determination device that detects whether or not the natural circulation operation is stopped by detecting the cooling capacity during the cooling operation by natural circulation is provided, and the stop determination device includes at least the intake air temperature and the blown air temperature of the evaporator Based on the difference with
When the natural circulation operation is stopped during the cooling operation by natural circulation, the valve device provided on the upstream side of the evaporator is fully closed, and the evaporator fan and the condenser fan are accelerated, and the liquid side connection is performed. Control is performed to increase the liquid refrigerant in the pipe and to increase the gas refrigerant in the gas side connection pipe, and then open the valve device on the upstream side of the evaporator to restart the natural circulation operation. An air conditioner comprising a control device.
請求項に記載の空気調和機であって、前記停止判定装置は、更に前記凝縮器用ファンの回転数、前記蒸発器用ファンの回転数、前記弁装置の開度、前記凝縮器の吸込空気温度、前記蒸発器の吸込空気温度の少なくとも1以上の情報も加えて、自然循環運転の停止有無を判定することを特徴とする空気調和機。 2. The air conditioner according to claim 1 , wherein the stop determination device further includes a rotation speed of the condenser fan, a rotation speed of the evaporator fan, an opening degree of the valve device, and an intake air temperature of the condenser. The air conditioner is characterized by determining whether or not the natural circulation operation is stopped by adding at least one piece of information on the intake air temperature of the evaporator. 請求項1または2に記載の空気調和機であって、自然循環運転時における前記蒸発器の吸込空気温度と空調対象室内の設定空気温度との差に基づいて、前記凝縮器用ファン、前記蒸発器用ファン、前記蒸発器上流側の弁装置の順に、必要に応じて低速側または低開度側へ順に制御して容量制御を行なうことを特徴とする空気調和機。 The air conditioner according to claim 1 or 2 , wherein the condenser fan and the evaporator are based on a difference between an intake air temperature of the evaporator and a set air temperature in an air-conditioning target room during natural circulation operation. An air conditioner that performs capacity control by sequentially controlling a fan and a valve device on the upstream side of the evaporator in order toward a low speed side or a low opening side as necessary. 請求項1または2に記載の空気調和機であって、前記液側接続配管はその途中に逆勾配となる部分が生じないように構成されていることを特徴とする空気調和機。 3. The air conditioner according to claim 1, wherein the liquid side connection pipe is configured such that a portion having a reverse gradient does not occur in the middle thereof. 4. 請求項に記載の空気調和機であって、前記ガス側接続配管もその途中に逆勾配となる部分が生じないように構成されていることを特徴とする空気調和機。 It is an air conditioner of Claim 4 , Comprising: The said gas side connection piping is comprised so that the part which becomes a reverse gradient may not arise in the middle. 請求項1または2に記載の空気調和機であって、前記液側接続配管を、前記蒸発器の高さ寸法に対し、該蒸発器下部から上方に向って1/4までの高さ寸法範囲位置で前記蒸発器に接続すると共に、前記ガス側接続配管を、前記蒸発器の高さ寸法に対し、該蒸発器上部から下方に向って1/4までの高さ寸法範囲位置で前記蒸発器に接続していることを特徴とする空気調和機。 It is an air conditioner of Claim 1 or 2 , Comprising: The said liquid side connection piping is a height dimension range up to 1/4 with respect to the height dimension of the said evaporator toward the upper direction from this evaporator lower part. The gas side connection pipe is connected to the evaporator at a position at a height dimension range position up to ¼ from the upper part of the evaporator toward the lower side with respect to the height dimension of the evaporator. An air conditioner characterized by being connected to. 請求項1に記載の空気調和機であって、強制循環運転用の圧縮機と、強制循環運転と自然循環運転を切り替える切替回路とを備え、
前記自然循環運転が停止した後、自然循環運転の再起動を行なうように前記制御装置で制御を行っても再起動できない場合には、前記制御装置は、前記切替回路を切り替えると共に前記圧縮機を起動して強制循環運転するように制御する
ことを特徴とする空気調和機。
The air conditioner according to claim 1, comprising a compressor for forced circulation operation, and a switching circuit for switching between forced circulation operation and natural circulation operation,
After the natural circulation operation is stopped, if the control device cannot be restarted even if control is performed to restart the natural circulation operation, the control device switches the switching circuit and the compressor. An air conditioner characterized by being controlled to start up and perform forced circulation operation.
請求項1またはに記載の空気調和機であって、冷媒としてR32またはR32を50%以上含む冷媒を用いることを特徴とする空気調和機。 The air conditioner according to claim 1 or 7 , wherein a refrigerant containing 50% or more of R32 or R32 is used as the refrigerant. 蒸発器と、この蒸発器よりも高い位置に設置された凝縮器と、前記蒸発器と前記凝縮器を接続する液側接続配管及びガス側接続配管と、前記蒸発器の上流側に設けられた弁装置と、前記蒸発器に送風するための蒸発器用ファンと、前記凝縮器に送風するための凝縮器用ファンとを備え、自然循環による冷凍サイクル運転を行う空気調和機の制御方法であって、
少なくとも前記蒸発器の吸込空気温度と吹出空気温度との差に基づいて自然循環運転の停止有無を判定し、
自然循環運転が停止した場合、前記蒸発器上流側に設けられた弁装置を全閉にすると共に、前記蒸発器用ファン及び前記凝縮器用ファンを増速させて前記液側接続配管に液冷媒を増加させ、前記ガス側接続配管にはガス冷媒を増加させるように制御し、その後前記蒸発器上流側の弁装置を開放させて自然循環運転の再起動を行なう
ことを特徴とする空気調和機の制御方法。
An evaporator, a condenser installed at a position higher than the evaporator, a liquid side connection pipe and a gas side connection pipe connecting the evaporator and the condenser, and an upstream side of the evaporator. A control method for an air conditioner comprising a valve device, an evaporator fan for blowing air to the evaporator, and a condenser fan for blowing air to the condenser, and performing a refrigeration cycle operation by natural circulation,
Determining whether or not to stop the natural circulation operation based on at least the difference between the intake air temperature and the blown air temperature of the evaporator,
When the natural circulation operation stops, the valve device provided upstream of the evaporator is fully closed, and the evaporator fan and the condenser fan are accelerated to increase the liquid refrigerant in the liquid side connection pipe. The gas-side connection pipe is controlled to increase the gas refrigerant, and then the valve device on the upstream side of the evaporator is opened to restart the natural circulation operation. Method.
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