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(11) | EP 0 247 638 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
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| (54) |
Refrigeration cycle apparatus Vorrichtung mit einem Kühlkreislauf Appareil à cycle de réfrigération |
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| Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
[0001] The present invention relates to a refrigerant cycle apparatus comprising: a compressor, a first heat exchanger operable as a condensor, an expansion means and a second heat exchanger operable as an evaporator connected in series with each other; means for repeatedly starting and stopping said compressor; and means for isolating refrigerant on a high pressure side of said compressor from refrigerant on a low pressure side of said compressor when said compressor is stopped.
[0003] One conventional refrigeration cycle apparatus includes a compressor, a condensor, an expansion device such as a capillary tube or an expansion valve, and an evaporator with these components sequentially coupled in series with each other. When the compressor is stopped, the pressure of the refrigerant on a high pressure side is balanced with the pressure of the refrigerant on the low pressure side. As the compressor is started, the difference between the pressures of the high pressure side and the low pressure side is gradually increased until the apparatus is brought to an ordinary operating state. When the compressor is accordingly repeatedly started and stopped, the high pressure side refrigerant is balanced with the low pressure side refrigerant each time the apparatus is stopped. During these times, the refrigerant liquid stored on the low pressure side in an evaporator is drawn into the compressor. The presence of the liquid refrigerant in the condensor increases the load on the compressor at the time of restarting the compressor. This lowers the coefficient of performance (hereinafter abbreviated as "COP") of the apparatus as compared with that during continuous operation.
[0004] This problem is mitigated by the apparatus described in US-A 3 093 976, but when the refrigeration cycle apparatus is used in an air temperature conditioning system capable of operating in both cooling and heating modes the refrigerant flow must be reversible. Conventional apparatus of this type is relatively expensive to manufacture and is relatively large.
[0005] An object of the invention is to simplify the construction of such apparatus thus enabling less expensive manufacture and reduction in size.
[0006] Another object of the invention is to enable the expansion coefficient of the apparatus to be varied between the heating and cooling modes in a simple manner.
[0007] According to the invention, the apparatus defined in the first paragraph of this specification where the isolating means excludes a check valve is characterised in that means are provided for reversing the functions of the first and second heat exchangers to provide for operation in a cooling or a heating mode, in that said expansion means comprises at least two series-connected capillary tube portions, in that a check valve is connected across one portion whereby the effective length of said expansion means may be changed, and in that said isolating means comprises a switching element provided between said capillary tube portions and arranged to close fully when said compressor is stopped and to open fully when said compressor is started.
[0008] The foregoing objects and other objects as well as the characteristic features of the invention will become more apparent and more readily understandable by the following description and the appended claims when read in conjunction with the accompanying drawings, the sole Figure of which is a schematic structural view showing a preferred embodiment of refrigeration cycle apparatus of the invention.
[0009] Reference is now made to the drawing showing a preferred embodiment of the refrigeration cycle apparatus, constructed according to the invention. Reference numeral I designates generally a compressor. A refrigerant gas compressed at high temperature and high pressure by the compressor I is fed through a valve 2 and a four-way valve 3 into a condenser 4. The refrigerant dissipates heat in the condenser 4 and is condensed to .a high temperature and high pressure liquid. The refrigerant liquid, increased in temperature and pressure by the condenser 4, is passed through a capillary tube 12 where the refrigerant becomes a low temperature, low pressure liquid and a switching element 14 which acts as a valve and from there is introduced into an evaporator 7. The low temperatur e and low pressure refrigerant liquid in the evaporator 7 absorbs heat and thus evaporates to a gas. This refrigerant gas is again fed through the four-way valve 3 into an accumulator 8 which isolates the refrigerant liquid which cannot be evaporated in the evaporator 7 and is retained in the liquid state and which returns only the refrigerant gas again to the compressor I. While the compressor I is operating, the apparatus repeats the refrigeration cycle.
[0010] Reference numeral 9 illustrates a fan for the condenser 4 and 10 a fan for the evaporator 7. The four-way valve 3 is a change-over or switching valve which operates so that the condenser 4 can be used as an evaporator and the evaporator 7 used as a condenser.
[0011] When this refrigeration cycle apparatus is used in a room air temperature conditioning system, the evaporator 7 is used as an indoor side heat exchanger, and the condenser 4 is used as an outdoor side heat exchanger. In the illustrated cooling mode, the apparatus is operated in a refrigeration cycle which in the heating mode is switched by the four-way valve 3 so that the indoor side heat exchanger 7 is used as a condenser and the outdoor side heat exchanger 4 is used as an evaporator.
[0012] The air temperature conditioning system operates to detect the temperature in the room by a temperature detector or thermostat (not shown) and to start or stop the compressor I so as to maintain the room temperature at a set temperature by operating or stopping the refrigeration cycle apparatus.
[0013] The switching element 14, which isolates the compressor I, is constructed so as to open when the compressor I is started and to close when the compressor I is stopped. The element 14 and the valve 2 function to isolate high pressure side refrigerant and low pressure side refrigerant when the compressor I is stopped.
[0014] In this refrigeration cycle apparatus used in an air temperature conditioning system as described above, when the compressor I is repeatedly started and stopped to maintain the room temperature at a set value, the element 14 is simultaneously opened and closed. Since the element 14 is closed when the compressor I is stopped, the high temperature and high pressure refrigerant liquid in the condenser 4 does not flow into the capillary tubes 12, 13 and accordingly does not flow into the evaporator 7. On the other hand, since the valve 2 is provided at the exhaust side of the compressor I, the refrigerant gas in the condenser 4 and the condensed refrigerant liquid cannot return to the compressor I.
[0015] When the compressor I is restarted, the high pressure side refrigerant in the refrigeration cycle is isolated from the low pressure side refrigerant. Since the element 14 is then opened, a desired pressure difference between the high and low pressure side refrigerant can be attained in short time and the apparatus can reach ordinary operating state in short time.
[0016] The conventional refrigerant cycle not incorporating such an isolating device requires about five minutes to reach the ordinary operation state after restarting. On the other hand, the refrigeration cycle apparatus of the invention requires only about one minute and twenty seconds to make the transition.
[0017] It is noted that the aforesaid switching element 14 may be a solenoid valve 5 or another type of switching valve and may be any type which closes when the compressor I is stopped and opens when the compressor I is started.
[0018] There is also provided a further capillary tube 13 in parallel with a check valve 15 which is constructed to pass the refrigerant in the illustrated cooling mode and to block the refrigerant in the non-illustrated heating mode with the valve 3 switched to its other position. The check valve 15 is provided to effectively alter the length of the total capillary tube 12, 13 since the apparatus will operate more efficiently if the expansion coefficient of the refrigerant is varied between the cooling mode and the heating mode in such a manner that the capillary tube is effectively increased in length in the heating mode.
[0019] With two capillary tubes 12 and 13 used instead of an expansion valve, the apparatus can be inexpensively constructed.
[0020] The switching element 14 is constructed to compare the pressure P2, determined by the output side refrigerant gas temperature of the evaporator 7 as detected by a heat sensitive tube provided between the outlet of the evaporator 7 and the inlet of the compressor I, with the pressure Pi of the refrigerant exhausted from the capillary tube 12, and to open when P2 > P1 and to close when P2 < P1, in the same manner as described above.
1. Refrigeration cycle apparatus comprising: a compressor (1), a first heat exchanger
(4) operable as a condensor, an expansion means (12, 13) and a second heat exchanger
(7) operable as an evaporator connected in series with each other; means for repeatedly
starting and stopping said compressor (1); and means (2, 14) excluding a check valve
for isolating refrigerant on a high pressure side of said compressor (1) from refrigerant
on a low pressure side of said compressor (1) when said compressor (1) is stopped,
characterised in that means (3) are provided for reversing the functions of the first
(4) and second (7) heat exchangers to provide for operation in a cooling or a heating
mode, in that said expansion means comprises at least two series-connected capillary
tube portions (12, 13), in that a check valve (15) is connected across one portion
(13) whereby the effective length of said expansion means may be changed, and in that
said isolating means comprises a switching element (14) provided between said capillary
tube portions (12, 13) and arranged to close fully when said compressor (1) is stopped
and to open fully when said compressor (1) is started.
2. Apparatus according to claim 1 wherein said effective length is increased in a
heating mode.
3. Apparatus according to any preceding claim wherein said reversing means (3) comprises
a four-way valve.
1. Kühlkreislaufvorrichtung mit: einem Verdichter (1), einem ersten Wärmetauscher
(4), der als Kondensator betreibbar ist, einer Expansionseinrichtung (12, 13) und
einem zweiten Wärmetauscher (7), der als ein Verdampfer betreibbar ist, die in Reihe
miteinander verbunden sind; einer Einrichtung zum wiederholten Starten und Stoppen
des Verdichters (1); und mit einer Einrichtung (2, 14) ohne ein Rückschlagventil zum
Dämmen des Kühlmittels auf einer Hochdruckseite des Verdichters (1) gegenüber einem
Kühlmittel auf einer Niedrigdruckseite des Verdichters (1), wenn der Verdichter (1)
gestoppt wird, dadurch gekennzeichnet, dass eine Einrichtung (3) zur Funktionsumkehrung
des ersten (4) und zweiten (7) Wärmetauschers vorgesehen ist, um einen Betrieb in
einer Kühl- oder einer Heizbetriebsweise zu schaffen, dass die Expansionseinrichtung
wenigstens zwei in Serie miteinander verbundene Kapillarrohrabschnitte (12, 13) aufweist,
dass ein Rückschlagventil (15) entlang eines Abschnittes (13) vorgesehen ist, wodurch
die effektive Länge der Expansionseinrichtung geändert werden kann, und dass die Dämmeinrichtung
ein Schaltelement (14) aufweist, das zwischen den Kapillarrohrabschnitten (12, 13)
angeordnet und dazu vorgesehen ist, sich völlig zu schliessen, wenn der Verdichter
(1) gestoppt wird, und sich völlig zu öffnen, wenn der Verdichter (1) gestartet wird.
2. Vorrichtung nach Anspruch 1, dadurch gekennzeichnet, dass die effektive Länge in
einer Heizbetriebsweise erhöht wird.
3. Vorrichtung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass
die Umkehreinrichtung (3) ein Vielwegeventil aufweist.
1. Appareil à cycle de réfrigération comprenant : un compresseur (1), un premier échangeur
de chaleur (4) pouvant fonctionner comme un condenseur, un moyen d'expansion (12,
13) et un second échangeur de chaleur (7) pouvant fonctionner comme un évaporateur
connectés en série les uns aux autres; des moyens pour mettre en route et arrêter
de façon répétée ledit compresseur (1); et des moyens (2, 14), excluant un clapet
de retenue, pour isoler le réfrigérant d'un côté haute pression dudit compresseur
(1) du réfrigérant sur un côté basse pression dudit compresseur (1) lorsque ledit
compresseur (1) est arrêté, caractérisé en ce qu'un moyen (3) est prévu pour inverser
les fonctions des premier (4) et second (7) échangeurs de chaleur afin de permettre
un fonctionnement dans un mode de refroidissement ou de chauffage, en ce que ledit
moyen d'expansion comprend au moins deux parties à tube capillaire (12, 13) connectées
en série, en ce qu'un clapet de retenue (15) est connecté en travers d'une partie
(13) de sorte que la longueur effective dudit moyen d'expansion peut changer, et en
ce que ledit moyen d'isolation comprend un élément de commutation (14) placé entre
lesdites parties à tube capillaire (12, 13) et disposé pour se fermer complètement
lorsque ledit compresseur (1) est arrêté et pour s'ouvrir complètement lorsque ledit
compresseur (1) est mis en route.
2. Appareil selon la revendication 1, dans lequel ladite longueur effective a lente
dans le mode de chauffage.
3. Appareil selon l'une quelconque des précédentes revendications, dans lequel ledit
moyen d'inversion (3) comprend une soupape à quatre voies.