JP3843963B2

JP3843963B2 - Heat pump water heater

Info

Publication number: JP3843963B2
Application number: JP2003140124A
Authority: JP
Inventors: 啓次郎國本; 竹司渡辺; 昌宏尾浜; 吉継西山; 浩二岡; 哲英倉本; 誠一安木
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 2003-05-19
Filing date: 2003-05-19
Publication date: 2006-11-08
Anticipated expiration: 2023-05-19
Also published as: JP2004340535A

Description

【０００１】
【発明の属する技術分野】
本発明は、ヒートポンプ給湯装置に関するものである。
【０００２】
【従来の技術】
従来のヒートポンプ給湯装置としては、特許文献１に記載されているようなヒートポンプ給湯装置が提案されていた。このヒートポンプ給湯装置は図３に示すように、圧縮機１と放熱器２と減圧手段３と吸熱器４とを含む冷媒循環回路５と、貯湯槽６と放熱器２と流量調整手段７とを有する給湯水回路８と、放熱器２に流入する給湯水回路８の入水温度と放熱器８から流出する冷媒循環回路５の高圧冷媒の出口温度との温度差が目標値になるように減圧手段３を制御する制御手段９を備えていた。また、制御手段９は圧縮機１から吐出される冷媒の吐出温度が規定値以上の場合は、前記の温度差の目標値を大きくするようにしていた。これにより、冷媒の吐出温度を圧縮機１の動作温度域に制御している。
【０００３】
しかし、この構成では吐出温度を直接制御できないので、例えば圧縮機１の運転周波数
や吐出温度、外気温度、設定給湯温度、入水温度などが変った場合に吐出温度が変化してしまい、安定した吐出温度とならない。また冷媒の出口温度は放熱器８で熱交換された後の温度であるため安定するのに時間がかかってしまい、適正な吐出温度や温度差を得るのに長い時間を要すなどの問題点があった。
【０００４】
【特許文献１】
特開２００２−１８８８５９号公報
【０００５】
【発明が解決しようとする課題】
本発明は、上記従来の課題を解決するもので、圧縮機からの冷媒の吐出温度を目標値に速く安定に制御し、耐久性が高く運転効率が良いヒートポンプ給湯装置を提供することを目的とする。
【０００６】
【課題を解決するための手段】
本発明は上記課題を解決するために、本発明のヒートポンプ給湯装置は、圧縮機と放熱器と減圧手段と吸熱器とを含む冷媒循環回路と、貯湯槽と前記放熱器と流量調整手段とを有する給湯水回路と、前記圧縮機の冷媒の吐出温度を前記減圧手段を制御することにより調整する吐出温度制御手段とを備え、前記吐出温度制御手段は、前記吐出温度に応じて前記減圧手段を制御する閉ループ制御と、外気温度と前記給湯水回路の放熱器の入口温度との値に応じて減圧手段を制御する開ループ制御とを備え、前記閉ループ制御と前記開ループ制御を組合わせて制御するとともに、運転起動時は前記開ループ制御のみを行うものである。
【０００７】
上記発明によれば、吐出温度を目標値に速く安定に制御できることができる。
【０００８】
【発明の実施の形態】
請求項１に記載の発明のヒートポンプ給湯装置は、圧縮機と放熱器と減圧手段と吸熱器とを含む冷媒循環回路と、貯湯槽と前記放熱器と流量調整手段とを有する給湯水回路と、前記圧縮機の冷媒の吐出温度を前記減圧手段を制御することにより調整する吐出温度制御手段とを備え、前記吐出温度制御手段は、前記吐出温度に応じて前記減圧手段を制御する閉ループ制御と、外気温度と前記給湯水回路の放熱器の入口温度との値に応じて減圧手段を制御する開ループ制御とを備え、前記閉ループ制御と前記開ループ制御を組合わせて制御するとともに、運転起動時は前記開ループ制御のみを行うものである。
【０００９】
この発明によれば、閉ループ制御により吐出温度を直接制御するので、正確に所定の吐出温度が得られる。また閉ループ制御と開ループ制御を組合わせてことで、圧縮機の運転周波数と外気温度と設定給湯温度と入口温度の変化にも素早く対応できる。
【００１０】
また、この発明によれば、運転の始動時や除霜運転から通常運転への切換時などの運転起動時に変動する吐出温度の影響を閉ループ運転を停止し開ループ制御のみで行うことにより、安定した減圧手段制御ができる。
【００１１】
請求項２に記載の発明のヒートポンプ給湯装置は、請求項１において、運転起動時から所定時間後に開ループ制御値を固定するようにしたものである。
【００１２】
この発明によれば、所定時間までは開ループ制御値するので、機器の温度状態が安定する間は圧縮機の運転周波数と外気温度と設定給湯温度と入口温度などの急変に対応できる。そして所定時間後に開ループ制御値を固定することで閉ループのみの制御とすることで、開ループと閉ループの両制御が干渉することなく正確に所定の温度に制御できる。
【００１３】
請求項３に記載の発明のヒートポンプ給湯装置は、冷媒循環回路を、冷媒の圧力が臨界圧力以上となる超臨界ヒートポンプサイクルであり、前記臨界圧力以上に昇圧された冷媒により貯湯槽内の水を加熱するように構成している。
【００１４】
この発明によれば、貯湯槽の水と熱交換する冷媒は、臨界圧力以上に加圧されているので、貯湯タンクの水により熱を奪われて温度低下しても凝縮することがない。したがって熱交換全域で冷媒と水とに温度差を形成しやすくなり、高温の湯が得られ、かつ熱交換効率を高くできる。
【００１５】
【実施例】
以下本発明の実施例について、図面を参照しながら説明する。
【００１６】
（実施例１）
図１は本発明の第１の実施例におけるヒートポンプ給湯装置の構成図を示す。本実施例は一般家庭用のヒートポンプ給湯装置で、主に割安な深夜電力を利用して給湯の湯を貯留するもので、圧縮機１０と放熱器１１と減圧手段１２と吸熱器１３とを直列に閉回路に接続した冷媒循環回路１４と、貯湯槽１５と放熱器１１と流量調整手段１６とを有する給湯水回路１７と、制御手段１８とで構成される。この冷媒循環回路１４は、例えば炭酸ガス（ＣＯ２）を冷媒として使用し、高圧側の冷媒圧力が冷媒の臨界圧以上となる超臨界ヒートポンプサイクルを使用している。そして圧縮機１０は、内蔵する電動モータ（図示しない）によって駆動され、吸引した冷媒を臨界圧力を超える圧力まで圧縮して吐出する。また、放熱器１１は冷媒循環回路１４の冷媒と、給湯水回路１７の水との熱交換を行うもので、例えば冷媒が流れる冷媒通路と水が流れる流水通路とが２重管構造に設けられ、且つ冷媒の流れ方向と流水の流れ方向が対向するように構成された対向流式熱交換器である。減圧手段１２は、内蔵するステッピングモータ（図示しない）を駆動させることにより流路の開度を可変させて冷媒の減圧量を変更する。吸熱器１３はファン（図示しない）によって大気熱を吸熱するように作用する。
【００１７】
給湯水回路１４は、貯湯槽１５内の水を所定量すなわち貯湯槽１５に高温の湯を満たすように流量調整手段１６を制御する。これは、貯湯槽１５底部から給水し貯湯槽１５上部に戻す循環構成で、貯湯槽１５内の沸き上げは、この給湯水回路１４の水を放熱器１１で所定温度に加熱して行う。流量調整手段１６はＤＣポンプを用いて電圧制御により流量を可変する。
【００１８】
１９は出湯温度設定手段で、貯湯槽１５の沸き上げ温度となる設定給湯温度を設定するものである。この設定給湯温度は、貯湯霜５での１日の湯の使用量や、水温などによって決定する。２０は冷媒の圧縮機１０の吐出温度を検出する吐出温度検出手段、２１は給湯水回路１４の放熱器１１への入水温度を検出する入水温度検出手段、２２は給湯水回路１４の放熱器１１からの出湯温度を検出する出湯温度検出手段、２３は外気温度を検出する外気温度検出手段である。また、２４は貯湯槽１５への給水管で、２５は貯湯槽１５から蛇口２６を接続する出湯管である。
【００１９】
次に図２に示す制御手段の動作系統図を用いて制御手段１８の構成と作用を説明する。２７は吐出温度制御手段であり、吐出温度と外気温度と入水温度と設定給湯温度と目標周波数に応じて減圧手段１２を制御する。そして、開ループ制御手段２８と、目標吐出温度設定手段２９と、閉ループ制御手段３０と、加算部３１より構成し、開ループ制御手段２８により減圧手段１２の基本開度を設定し、閉ループ制御手段３０により吐出温度が目標値になるようにフィードバック制御の制御量を設定し、加算部３１で開ループ制御手段２８と閉ループ制御手段３０の設定値を加算して減圧手段１２を制御している。
【００２０】
開ループ制御手段２８は、外気温度検出手段２３と入水温度検出温度２１と出湯温度設定手段１９の三者の温度の組合わせから最適な減圧手段１２の開度を設定する。ここで設定する値は、前記三者の組合わせにおける最適値を予め求めて数値化し、メモリ（図示しない）に記憶させ用いる。この開ループ制御は、運転開始時や除霜運転から通常運転に切替わった場合などの運転再開時に、運転が開始されてから所定時間（例えば５分間）経過後の値で固定するように設定している。これは、外気温度検出手段２３や入水温度検出手段２１の検出値が停止時や除霜時に周囲温度に影響されて急変する時間帯は、この変化に対応するために開ループ制御を用いて制御し、外気温度や入水温度が本来の値に落ち着く時間になれば開ループ制御の値を固定して、閉ループ制御との干渉を防止するように作用する。なお、開ループ制御における誤差が少なければ閉ループとの干渉なく外乱に対して素早い制御が可能となるため、継続してもよい。
【００２１】
目標吐出温度設定手段２９は、出湯温度設定手段１９の設定給湯温度に所定温度差を加算して設定する。この所定温度差は、外気温度検出手段２３と入水温度検出手段１９と目標周波数設定手段３２のそれぞれの値によって変更する。変更する条件は吐出温度が適正な温度範囲に納まり、異常な吐出圧力や圧縮機のモータ過電流にならないでかつ効率のよい運転となるように設定する。この所定温度差も外気温度と入水温度と周波数の組合わせにおける最適値を予め求めて数値化し、メモリ（図示しない）に記憶させ用いる。
【００２２】
閉ループ制御手段３０は、吐出温度検出手段２０の検出値が目標吐出温度設定手段２９の設定する目標値になるようにフィードバック制御する。すなわち目標値に対して検出値が低ければ減圧手段１２の開度を絞るように設定し、高ければ開くように設定する。制御方法は公知のＰ制御やＰＩ制御、ＰＩＤ制御、ファジー制御等を用いてもよい。この閉ループ制御は、運転開始時や除霜運転から通常運転に切替わった場合などの運転再開時に、運転が開始されてから所定時間（例えば吐出温度が所定値に達するまでの時間）は閉ループ制御をしないで開ループ制御のみで運転するようにしている。これは、吐出温度が目標値より大幅に低い場合にフィードバック制御をすると、減圧手段１２の開度を絞り過ぎて吐出圧力が異常上昇してしまう場合があり、これを防止する効果がある。
【００２３】
目標周波数設定手段３２は、外気温度検出手段２３と入水温度検出温度２１と出湯温度設定手段１９の三者の温度の組合わせから最適な圧縮機１０の運転周波数を設定する。ここで設定する値は、所要な給湯能力を得るのに必要な前記三者の組合わせにおける最適値を予め求めて数値化し、メモリ（図示しない）に記憶させ用いる。最適値は給湯能力だけではなく運転効率と圧縮機の吐出圧力、吸入圧力、吐出温度、圧縮機のモータ電流などの総合的な運転状態を判断して決定する。
【００２４】
出湯温度制御手段３３は、入水温度検出手段２１と出湯温度検出手段２２と出湯温度設定手段１９の値に応じて、出湯温度が設定給湯温度になるよう流量調整手段１６を制御する。すなわち、出湯温度が低ければ流量調整手段１６の流量を低下させ、高ければ流量を増加させるように制御する。具体的には設定給湯温度と出湯温度との温度偏差により公知のＰＩ制御によりフィードバック制御する。加えて設定給湯温度と入水温度との偏差に反比例する係数を乗じて基本制御量としてフィードバック値に加算して流量調整手段１６を制御する。すなわち、同一な給湯能力の場合、設定給湯温度と入水温度の偏差が大きいと必要流量は少なくてすみ、逆に偏差が大きいと必要流量は多くなる。この点を加味して基本制御量を設定する。なお、フィードバック制御はＰＩ制御としたが、Ｐ制御、ＰＩＤ制御、ファジー制御でもよい。
【００２５】
以上実施例１の構成によれば、高圧側の冷媒圧力が冷媒の臨界圧以上となる超臨界ヒートポンプサイクルを使用して、放熱器に冷媒の流れ方向と流水の流れ方向が対向する対向流式熱交換器を採用しているので、高温でかつ効率の良い給湯ができる。
【００２６】
また、吐出温度の目標値として外気温度と入水温度と設定給湯温度と目標周波数から最適な値が設定され、吐出温度がこの目標値になるように閉ループ制御手段により減圧手段を制御するので、吐出温度を確実に目標値に制御することができる。さらに、開ループ制御手段によって外気温度や入水温度、設定給湯温度に応じた減圧手段の最適開度が設定される。したがって常に冷媒回路に適正な冷媒が循環するため、異常温度上昇や異常圧力上昇がなく、そのため、耐久性が高く、運転効率も良くすることができる。
【００２７】
なお、実施例では加熱手段に超臨界ヒートポンプサイクルを用いたが、もちろん通常のヒートポンプサイクルでも良い。
【００２８】
また、その場合の冷媒としてはフロンガス、アンモニア、ハイドロカーボン冷媒（プロパン、ブタンなど）が有用である。
【００２９】
【発明の効果】
以上のように、本発明によれば、本発明は圧縮機からの冷媒の吐出温度を目標値に速く安定に制御することができ、耐久性が高く運転効率が良いヒートポンプ給湯装置を提供することができる。
【図面の簡単な説明】
【図１】本発明の実施例１におけるヒートポンプ給湯装置の構成図
【図２】同実施例１におけるヒートポンプ給湯装置の制御手段の動作系統図
【図３】従来のヒートポンプ給湯装置の構成図
【符号の説明】
１０圧縮機
１１放熱器
１２減圧手段
１３吸熱器
１４冷媒循環回路
１５貯湯槽
１６流量調整手段
１７給湯水回路
１９出湯温度設定手段
２０吐出温度検出手段
２１入水温度検出手段
２３外気温度検出手段
２７吐出温度制御手段
２８開ループ制御手段
３０閉ループ制御手段
３２目標周波数設定手段[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat pump water heater.
[0002]
[Prior art]
As a conventional heat pump hot water supply apparatus, a heat pump hot water supply apparatus as described in Patent Document 1 has been proposed. As shown in FIG. 3, the heat pump hot water supply apparatus includes a refrigerant circulation circuit 5 including a compressor 1, a radiator 2, a decompression unit 3, and a heat absorber 4, a hot water storage tank 6, a radiator 2, and a flow rate adjustment unit 7. Depressurizing means so that the temperature difference between the hot water supply circuit 8 and the incoming water temperature of the hot water supply circuit 8 flowing into the radiator 2 and the outlet temperature of the high-pressure refrigerant of the refrigerant circulation circuit 5 flowing out of the radiator 8 becomes a target value. The control means 9 which controls 3 was provided. The control means 9 increases the target value of the temperature difference when the discharge temperature of the refrigerant discharged from the compressor 1 is equal to or higher than a specified value. Thereby, the discharge temperature of the refrigerant is controlled within the operating temperature range of the compressor 1.
[0003]
However, since the discharge temperature cannot be directly controlled in this configuration, for example, when the operating frequency, discharge temperature, outside air temperature, set hot water supply temperature, incoming water temperature, etc. of the compressor 1 change, the discharge temperature changes, and stable discharge It does not become temperature. Further, since the outlet temperature of the refrigerant is a temperature after heat exchange with the radiator 8, it takes time to stabilize, and it takes a long time to obtain an appropriate discharge temperature and temperature difference. was there.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-188859
[Problems to be solved by the invention]
An object of the present invention is to solve the above-described conventional problems, and to provide a heat pump hot water supply apparatus that controls the refrigerant discharge temperature from the compressor quickly and stably to a target value, and has high durability and good operating efficiency. To do.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a heat pump water heater of the present invention comprising a refrigerant circulation circuit including a compressor, a radiator, a decompression unit, and a heat absorber, a hot water tank, the radiator, and a flow rate adjustment unit. A hot water supply circuit having a discharge temperature control means for adjusting the discharge temperature of the refrigerant of the compressor by controlling the pressure reduction means, wherein the discharge temperature control means controls the pressure reduction means according to the discharge temperature. A closed loop control for controlling, and an open loop control for controlling the pressure reducing means according to the values of the outside air temperature and the inlet temperature of the radiator of the hot water supply circuit, and the control is performed by combining the closed loop control and the open loop control. At the same time, only the open loop control is performed at the start of operation .
[0007]
According to the above invention, the discharge temperature can be quickly and stably controlled to the target value.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The heat pump hot water supply apparatus of the invention described in claim 1 includes a refrigerant circulation circuit including a compressor, a radiator, a decompression unit, and a heat absorber, a hot water supply circuit having a hot water storage tank, the radiator, and a flow rate adjustment unit, Discharge temperature control means for adjusting the discharge temperature of the refrigerant of the compressor by controlling the pressure reducing means, the discharge temperature control means is a closed loop control for controlling the pressure reducing means in accordance with the discharge temperature; An open loop control that controls the decompression means according to the value of the outside air temperature and the inlet temperature of the radiator of the hot water supply circuit, and controls the combination of the closed loop control and the open loop control. Performs only the open loop control.
[0009]
According to the present invention, since the discharge temperature is directly controlled by closed loop control, a predetermined discharge temperature can be obtained accurately. Further, by combining the closed loop control and the open loop control, it is possible to quickly cope with changes in the operating frequency of the compressor, the outside air temperature, the set hot water temperature, and the inlet temperature .
[0010]
Further , according to the present invention, the effect of the discharge temperature, which fluctuates at the start of the operation or at the start of the operation such as switching from the defrosting operation to the normal operation, is stopped by stopping the closed loop operation and performing only the open loop control. The decompression means can be controlled.
[0011]
The heat pump hot water supply apparatus according to the second aspect of the present invention is the heat pump hot water supply apparatus according to the first aspect, wherein the open loop control value is fixed after a predetermined time from the start of operation.
[0012]
According to the present invention, since the open loop control value is maintained until a predetermined time, it is possible to cope with sudden changes such as the operating frequency of the compressor, the outside air temperature, the set hot water temperature, and the inlet temperature while the temperature state of the equipment is stabilized. Then, by fixing the open-loop control value after a predetermined time, it is possible to control to the predetermined temperature accurately without interference between both the open-loop control and the closed-loop control.
[0013]
A heat pump hot water supply apparatus according to a third aspect of the present invention is a supercritical heat pump cycle in which the refrigerant pressure is equal to or higher than the critical pressure in the refrigerant circulation circuit, and water in the hot water storage tank is supplied by the refrigerant whose pressure is increased to the critical pressure or higher. It is configured to heat.
[0014]
According to this invention, since the refrigerant that exchanges heat with the water in the hot water tank is pressurized to a critical pressure or higher, it does not condense even if the heat is taken away by the water in the hot water tank and the temperature drops. Therefore, it becomes easy to form a temperature difference between the refrigerant and water over the entire heat exchange, and hot water can be obtained, and the heat exchange efficiency can be increased.
[0015]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0016]
Example 1
FIG. 1 shows a block diagram of a heat pump hot water supply apparatus in a first embodiment of the present invention. The present embodiment is a heat pump hot water supply device for general households, which mainly stores hot water for hot water using cheap midnight power. The compressor 10, the radiator 11, the decompression means 12, and the heat absorber 13 are connected in series. The refrigerant circulation circuit 14 is connected to the closed circuit, the hot water tank 15, the radiator 11, and the flow rate adjusting means 16, and the control means 18. This refrigerant circuit 14 uses, for example, carbon dioxide (CO2) as a refrigerant, and uses a supercritical heat pump cycle in which the refrigerant pressure on the high pressure side is equal to or higher than the critical pressure of the refrigerant. The compressor 10 is driven by a built-in electric motor (not shown), and compresses and sucks the sucked refrigerant to a pressure exceeding the critical pressure. The radiator 11 performs heat exchange between the refrigerant in the refrigerant circulation circuit 14 and the water in the hot water supply circuit 17. For example, a refrigerant passage through which refrigerant flows and a flowing water passage through which water flows are provided in a double pipe structure. And it is a counterflow type heat exchanger comprised so that the flow direction of a refrigerant | coolant and the flow direction of flowing water may oppose. The decompression means 12 changes the decompression amount of the refrigerant by driving a built-in stepping motor (not shown) to vary the opening of the flow path. The heat absorber 13 acts to absorb atmospheric heat by a fan (not shown).
[0017]
The hot water supply circuit 14 controls the flow rate adjusting means 16 so that the hot water in the hot water storage tank 15 is filled with a predetermined amount, that is, hot water in the hot water storage tank 15. This is a circulation configuration in which water is supplied from the bottom of the hot water tank 15 and returned to the upper part of the hot water tank 15, and boiling in the hot water tank 15 is performed by heating the water in the hot water circuit 14 to a predetermined temperature by the radiator 11. The flow rate adjusting means 16 varies the flow rate by voltage control using a DC pump.
[0018]
Reference numeral 19 denotes a hot water temperature setting means for setting a set hot water supply temperature which is the boiling temperature of the hot water storage tank 15. This set hot water supply temperature is determined by the amount of hot water used in the hot water storage frost 5 for one day, the water temperature, and the like. Reference numeral 20 denotes discharge temperature detection means for detecting the discharge temperature of the refrigerant compressor 10, reference numeral 21 denotes incoming water temperature detection means for detecting the incoming water temperature to the radiator 11 of the hot water supply circuit 14, and reference numeral 22 denotes radiator 11 of the hot water supply circuit 14. The hot water temperature detecting means for detecting the hot water temperature from the hot water, 23 is an outdoor air temperature detecting means for detecting the outdoor air temperature. Reference numeral 24 denotes a water supply pipe to the hot water tank 15, and 25 denotes a hot water pipe connecting the faucet 26 from the hot water tank 15.
[0019]
Next, the configuration and operation of the control means 18 will be described using the operation system diagram of the control means shown in FIG. 27 is a discharge temperature control means, which controls the decompression means 12 according to the discharge temperature, the outside air temperature, the incoming water temperature, the set hot water supply temperature, and the target frequency. Then, the open loop control means 28, the target discharge temperature setting means 29, the closed loop control means 30, and the adding unit 31 are configured, and the basic opening degree of the decompression means 12 is set by the open loop control means 28, and the closed loop control means The amount of feedback control is set by 30 so that the discharge temperature becomes a target value, and the setting unit 31 adds the set values of the open loop control means 28 and the closed loop control means 30 to control the decompression means 12.
[0020]
The open loop control means 28 sets the optimum opening of the decompression means 12 from the combination of the three temperatures of the outside air temperature detection means 23, the incoming water temperature detection temperature 21, and the tapping temperature setting means 19. As the value set here, an optimum value in the combination of the three is obtained in advance and digitized, and stored in a memory (not shown) for use. This open loop control is set to be fixed at a value after a predetermined time (for example, 5 minutes) has elapsed since the operation was started when the operation was restarted, such as when the operation was started or when the defrost operation was switched to the normal operation. is doing. This is because the time zone in which the detected values of the outside air temperature detecting means 23 and the incoming water temperature detecting means 21 change suddenly due to the ambient temperature at the time of stopping or defrosting is controlled using open loop control in order to cope with this change. However, when it is time for the outside air temperature or the incoming water temperature to settle to the original value, the value of the open loop control is fixed, and the interference with the closed loop control is prevented. Note that if the error in the open loop control is small, quick control can be performed with respect to the disturbance without interference with the closed loop.
[0021]
The target discharge temperature setting means 29 is set by adding a predetermined temperature difference to the set hot water supply temperature of the tapping temperature setting means 19. This predetermined temperature difference is changed according to the respective values of the outside air temperature detection means 23, the incoming water temperature detection means 19 and the target frequency setting means 32. The conditions to be changed are set so that the discharge temperature is within an appropriate temperature range, an abnormal discharge pressure and a motor overcurrent of the compressor do not occur, and the operation is efficient. For this predetermined temperature difference, an optimum value for the combination of the outside air temperature, the incoming water temperature, and the frequency is obtained in advance and digitized, and stored in a memory (not shown) for use.
[0022]
The closed loop control unit 30 performs feedback control so that the detection value of the discharge temperature detection unit 20 becomes the target value set by the target discharge temperature setting unit 29. That is, when the detected value is lower than the target value, the opening degree of the decompression means 12 is set to be reduced, and when it is higher, the opening is set to be opened. As a control method, known P control, PI control, PID control, fuzzy control, or the like may be used. This closed-loop control is a closed-loop control for a predetermined time (for example, the time until the discharge temperature reaches a predetermined value) after the operation is started, such as when the operation is started or when the operation is switched from the defrosting operation to the normal operation. It is designed to operate only with open loop control. If feedback control is performed when the discharge temperature is significantly lower than the target value, the opening of the decompression means 12 may be excessively narrowed and the discharge pressure may rise abnormally, and this has the effect of preventing this.
[0023]
The target frequency setting means 32 sets the optimum operating frequency of the compressor 10 from the combination of the three temperatures of the outside air temperature detection means 23, the incoming water temperature detection temperature 21 and the hot water temperature setting means 19. As the value set here, an optimum value in the combination of the three necessary for obtaining a required hot water supply capacity is obtained in advance and digitized, and stored in a memory (not shown) for use. The optimum value is determined by judging not only the hot water supply capacity but also the overall operation state such as operation efficiency, compressor discharge pressure, suction pressure, discharge temperature, and compressor motor current.
[0024]
The hot water temperature control means 33 controls the flow rate adjusting means 16 so that the hot water temperature becomes the set hot water supply temperature according to the values of the incoming water temperature detection means 21, the hot water temperature detection means 22, and the hot water temperature setting means 19. That is, control is performed such that the flow rate of the flow rate adjusting means 16 is reduced when the temperature of the hot water is low and the flow rate is increased when the temperature is high. Specifically, feedback control is performed by known PI control based on a temperature deviation between the set hot water supply temperature and the tapping temperature. In addition, the flow rate adjusting means 16 is controlled by multiplying a coefficient inversely proportional to the deviation between the set hot water supply temperature and the incoming water temperature and adding it to the feedback value as a basic control amount. That is, in the case of the same hot water supply capacity, if the deviation between the set hot water supply temperature and the incoming water temperature is large, the required flow rate is small, and conversely, if the deviation is large, the necessary flow rate is large. Considering this point, the basic control amount is set. Although feedback control is PI control, P control, PID control, and fuzzy control may be used.
[0025]
As described above, according to the configuration of the first embodiment, using the supercritical heat pump cycle in which the refrigerant pressure on the high pressure side is equal to or higher than the critical pressure of the refrigerant, the counterflow type in which the refrigerant flow direction and the flowing water flow direction are opposed to the radiator. Since a heat exchanger is used, hot water can be supplied efficiently at high temperatures.
[0026]
In addition, as the target value of the discharge temperature, an optimum value is set from the outside air temperature, the incoming water temperature, the set hot water temperature and the target frequency, and the decompression means is controlled by the closed loop control means so that the discharge temperature becomes this target value. The temperature can be reliably controlled to the target value. Furthermore, the optimum opening degree of the decompression means according to the outside air temperature, the incoming water temperature, and the set hot water supply temperature is set by the open loop control means. Therefore, since an appropriate refrigerant circulates in the refrigerant circuit at all times, there is no abnormal temperature rise or abnormal pressure rise, so that durability is high and operational efficiency can be improved.
[0027]
In the embodiment, a supercritical heat pump cycle is used as the heating means, but a normal heat pump cycle may be used.
[0028]
Further, as the refrigerant in that case, chlorofluorocarbon gas, ammonia, and a hydrocarbon refrigerant (propane, butane, etc.) are useful.
[0029]
【The invention's effect】
As described above, according to the present invention, the present invention provides a heat pump hot water supply apparatus that can quickly and stably control the refrigerant discharge temperature from the compressor to a target value, and has high durability and high operating efficiency. Can do.
[Brief description of the drawings]
1 is a configuration diagram of a heat pump water heater in Embodiment 1 of the present invention. FIG. 2 is an operation system diagram of control means of the heat pump water heater in Embodiment 1. FIG. 3 is a configuration diagram of a conventional heat pump water heater. Explanation of]
DESCRIPTION OF SYMBOLS 10 Compressor 11 Radiator 12 Pressure reducing means 13 Heat absorber 14 Refrigerant circulation circuit 15 Hot water storage tank 16 Flow rate adjusting means 17 Hot water supply circuit 19 Hot water temperature setting means 20 Discharge temperature detection means 21 Incoming water temperature detection means 23 Outside air temperature detection means 27 Discharge temperature Control means 28 Open loop control means 30 Closed loop control means 32 Target frequency setting means

Claims

A refrigerant circulation circuit including a compressor, a radiator, a decompression unit, and a heat absorber; a hot water supply circuit having a hot water storage tank, the radiator, and a flow rate adjustment unit; and a refrigerant discharge temperature of the compressor, the decompression unit Discharge temperature control means for adjusting by controlling, the discharge temperature control means, closed loop control for controlling the pressure reducing means according to the discharge temperature, outside temperature and inlet temperature of the radiator of the hot water supply circuit And an open loop control that controls the decompression means in accordance with the value of the above, and controls the combination of the closed loop control and the open loop control, and performs only the open loop control at the start of operation .

The heat pump hot water supply device according to claim 1 , wherein the open loop control value is fixed after a predetermined time from the start of operation.

The heat pump water heater according to claim 1 or 2 , wherein the refrigerant circulation circuit is a supercritical heat pump cycle in which the pressure of the refrigerant becomes equal to or higher than a critical pressure, and water in the hot water tank is heated by the refrigerant whose pressure is increased to the critical pressure or higher.