Outdoor unit with at least three compressors for use with air conditioners

Description

{Technical Field}

[0001] The present invention relates to outdoor units for use with air conditioners, and particularly to an outdoor unit including at least three compressors and having an oil equalization mode function for maintaining the proper oil level in each of the compressors.

{Background Art}

[0002] PTL 1 discloses an example of a known outdoor unit including at least three compressors and having an oil equalization mode function for maintaining the proper oil level in each of the compressors.

[0003] US 2008/0209924 discloses a system having a plurality of compressors and an oil separator for removing oil from a refrigerant fluid. The system performs an oil balancing operation during which some compressors operate and some do not, and a series of valves are manipulated to direct oil flow.

[0004] EP 2 023 060 discloses a system including three compressors in parallel and having an oil separator for removing oil from a refrigerant liquid. A flow biasing element is implemented to direct greater portions of oil to a compressor requiring said oil.

{Citation List}

[0005] {PTL 1} Japanese Unexamined Patent Application, Publication No. 2005-188365

{Summary of Invention}

{Technical Problem}

[0006] The outdoor unit disclosed in PTL 1 above, however, has a step of stopping a first compressor and a second compressor and operating only a third compressor and a step of operating only the first compressor and stopping the second compressor and the third compressor. Therefore, when the outdoor unit disclosed in PTL 1 above is at a high load (when many indoor units are operating), the indoor units may face a capacity shortfall.

[0007] An object of the present invention, which has been made in light of such circumstances, is to provide an outdoor unit that can prevent a capacity shortfall in indoor units at a high load.

{Solution to Problem}

[0008] To solve the above problem, the present invention employs the following solutions.

[0009] An outdoor unit according an aspect of the present invention includes at least three compressors and has an oil equalization mode function for maintaining a proper oil level in each of the compressors. The outdoor unit includes a controller that controls starting and stopping of the compressors in the oil equalization mode such that one of the compressors at a time is stopped or operated at a low load while the other compressors are operated.

[0010] In the oil equalization mode of the outdoor unit according to the aspect of the present invention, one of the compressors is stopped or operated at a low load while the other compressors (at least two compressors) are operating normally.

[0011] This prevents a capacity shortfall in an indoor unit at a high load.

[0012] In the above outdoor unit, the controller preferably controls the starting and stopping of the compressors in the oil equalization mode such that the compressors are each started before another compressor is stopped or transitions to low-load operation so that the operation of the started compressor is established at the same time as when the other compressor is stopped or completes the transition to low-load operation.

[0013] In this type of outdoor unit, the inner pressures of oil-equalizing branch pipes at (near) oil-equalizing-pipe connection ports of the compressors operating normally are (substantially) equal when the operation of the started compressor is established.

[0014] This allows the oil to be (substantially) evenly distributed over the compressors operating normally.

[0015] A multi-type air conditioner according to an aspect of the present invention includes one of the above types of outdoor units.

[0016] In the oil equalization mode of the outdoor unit included in the above multi-type air conditioner, one of the compressors is stopped or operated at a low load while the other compressors (at least two compressors) are operating normally.

[0017] This prevents a capacity shortfall in an indoor unit at a high load, thus constantly maintaining a comfortable indoor environment.

[0018] A method for operating an outdoor unit according to an aspect of the present invention is a method for operating an outdoor unit including at least three compressors and having an oil equalization mode function for maintaining a proper oil level in each of the compressors. The compressors are started and stopped in the oil equalization mode such that one of the compressors at a time is stopped or operated at a low load while the other compressors are operated.

[0019] In the oil equalization mode of the above method for operating the outdoor unit, one of the compressors at a time is stopped or operated at a low load while the other compressors (at least two compressors) are operating normally. This prevents a capacity shortfall in an indoor unit at a high load.

[0020] In the above method for operating the outdoor unit, the compressors are preferably started and stopped in the oil equalization mode such that the compressors are each started before another compressor is stopped or transitions to slow-load operation so that the operation of the started compressor is established at the same time as when the other compressor is stopped or completes the transition to low-load operation.

[0021] In this method for operating the outdoor unit, the inner pressures of oil-equalizing branch pipes at (near) oil-equalizing-pipe connection ports of the compressors operating normally are (substantially) equal when the operation of the started compressor is established.

[0022] This allows the oil to be (substantially) evenly distributed over the compressors operating normally.

{Advantageous Effects of Invention}

[0023] The outdoor unit according to the aspect of the present invention provides the advantage of preventing a capacity shortfall in an indoor unit at a high load.

{Brief Description of Drawings}

[0024] 

{Fig. 1} Fig. 1 is a table showing the operational status of each compressor according to an embodiment of the present inverition.

{Fig. 2A} Fig. 2A is a diagram showing oil flow in a step shown in Fig. 1.

{Fig. 2B} Fig. 2B is a diagram showing oil flow in a step shown in Fig. 1.

{Fig. 2C} Fig. 2C is a diagram showing oil flow in a step shown in Fig. 1.

{Fig. 3} Fig. 3 is a timing chart showing the relationship between the ON/OFF state of each compressor and operating time in the embodiment of the present invention.

{Description of Embodiments}

[0025] An outdoor unit according to an embodiment of the present invention will now be described with reference to Figs. 1 to 3.

[0026] Fig. 1 is a table showing the operational status of each compressor according to this embodiment. Figs. 2A to 2C are diagrams showing oil flow in the respective steps shown in Fig. 1. Fig. 3 is a timing chart showing the relationship between the ON/OFF state of each compressor and operating time in this embodiment.

[0027] As shown in Figs. 2A to 2C, an outdoor unit 10 according to this embodiment includes at least three (in this embodiment, three) compressors CM1, CM2, and CM3, an oil-equalizing pipe 11, and a controller 12 and is connected to a plurality of indoor units (not shown) via refrigerant piping (not shown).

[0028] The oil-equalizing pipe 11 includes a first oil-equalizing branch pipe 31 through which an oil-equalizing pipe node P communicates with (connects to) an oil-equalizing-pipe connection port 21 of the (first) compressor CM1, a second oil-equalizing branch pipe 32 through which the oil-equalizing pipe node P communicates with (connects to) an oil-equalizing-pipe connection port 22 of the (second) compressor CM2, and a third oil-equalizing branch pipe 33 through which the oil-equalizing pipe node P communicates with (connects to) an oil-equalizing-pipe connection port 23 of the (third) compressor CMS.

[0029] The controller 12 controls starting and stopping (start/stop) of the compressors CM1, CM2, and CM3 according to the table shown in Fig. 1 and the chart shown in Fig. 3. That is, the compressors CM1, CM2, and CM3 are each started (ON) and stopped (OFF) in response to an instruction signal (control signal) transmitted by the controller 12.

[0030] In the outdoor unit 10 according to this embodiment, the controller 12 controls the starting and stopping of the compressors CM1, CM2, and CM3 in an oil equalization mode (i.e., step 1 to step 3) such that one of the compressors CM1, CM2, and CM3 at a time is stopped (in the order CM3 → CM1 → CM2) while the other compressors are operated (in the order CM1, CM2 → CM2, CM3 → CM1, CM3). That is, the compressors CM1, CM2, and CM3 are each started and stopped in response to an instruction signal (control signal) transmitted by the controller 12 in the oil equalization mode such that the compressors CM1 and CM2 operate while the compressor CM3 is stopped, that the compressors CM2 and CM3 operate while the compressor CM1 is stopped, and that the compressors CM1 and CM3 operate while the compressor CM2 is stopped.

[0031] In the oil equalization mode of the outdoor unit 10 according to this embodiment, the starting (rise) of the compressors CM1, CM2, and CM3 does not occur at the same time as the stopping (fall) of the compressors CM1, CM2, and CM3. That is, as indicated by the lines rising to the right in Fig. 3, the compressors CM1, CM2, and CM3 are each started slightly before another compressor CM1, CM2, or CM3 is stopped so that the operation of the started compressor CM1, CM2, or CM3 is established at the same time as when the other compressor CM1, CM2, or CM3 is stopped.

[0032] According to the outdoor unit 10 and the method for operating the outdoor unit 10 according to this embodiment, in the oil equalization mode, any one of the compressors CM1, CM2, and CM3 is stopped while the other compressors (at least two compressors) CM1, CM2, and CM3 are operating normally.

[0033] This prevents a capacity shortfall in the indoor units at a high load.

[0034] In the outdoor unit 10 and the method for operating the outdoor unit 10 according to this embodiment, the inner pressures of the oil-equalizing branch pipes 31, 32, and 33 at (near) the oil-equalizing-pipe connection ports 21, 22, and 23 of the compressors CM1, CM2, and CM3 operating normally are (substantially) equal when the operation of the started compressor CM1, CM2, or CM3 is established.

[0035] This allows the oil to be (substantially) evenly distributed over the compressors CM1, CM2, and CM3 operating normally.

[0036] In the oil equalization mode of a multi-type air conditioner (not shown) including the outdoor unit 10 according to this embodiment, any one of the compressors CM1, CM2, and CM3 is stopped while the other compressors (at least two compressors) CM1, CM2, and CM3 are operating normally.

[0037] This prevents a capacity shortfall in the indoor units at a high load.

[0038] While the above embodiment has been illustrated with the example in which any one of the compressors CM1, CM2, and CM3 is stopped in the oil equalization mode, the present invention is not limited thereto; any one of the compressors CM1, CM2, and CM3 may be operated at a lower load than the other compressors CM1, CM2, and CM3 operating normally, or at a lower rotational speed than the other compressors CM1, CM2, and CM3 operating normally.

{Reference Signs List}

[0039] 

10

outdoor unit

11

oil-equalizing pipe

12

controller

21

oil-equalizing-pipe connection port

22

oil-equalizing-pipe connection port

23

oil-equalizing-pipe connection port

31

oil-equalizing branch pipe

32

oil-equalizing branch pipe

22

oil-equalizing-pipe connection port

23

oil-equalizing-pipe connection port

31

oil-equalizing branch pipe

32

oil-equalizing branch pipe

33

oil-equalizing branch pipe

CM1

compressor

CM2

compressor

CM3

compressor

Claims

1. An outdoor unit (10) comprising at least three compressors (CM1, CM2, CM3) the outdoor unit being configured with an oil equalization mode function configured to maintain a proper oil level in each of the compressors (CM1, CM2, CM3),
the outdoor unit (10) characterized in that it comprises a controller (12) configured to control the starting and stopping of the compressors (CM1, CM2, CM3) in the oil equalization mode such that one of the at least three compressors (CM1, CM2, CM3) at a time is stopped or operated at a low load while being configured to cause the other of the at least three compressors (CM1, CM2, CM3) to operate, wherein the at least three compressors (CM1, CM2, CM3) comprise a first compressor (CM1) and a second compressor (CM2),
wherein during the oil equalization mode, the controller (12) is configured to cause the second compressor (CM2), which is stopped or in a low-load operation, to begin starting up before the first compressor (CM1), which is in operation but is to be stopped or operated in a low-load condition, reaches low-load operation or is completely stopped, and
the controller (12) is configured to control the starting and stopping of each of the at least three compressors (CM1, CM2, CM3) so that the operation of starting up the second compressor (CM2) is completed at the same time as when the first compressor (CM1) is stopped or completes the transition to low-load operation.

2. A multi-type air conditioner comprising the outdoor unit (10) according to Claim 1.

3. A method for operating an outdoor unit (10) including at least three compressors (CM1, CM2, CM3) and having an oil equalization mode function for maintaining a proper oil level in each of the compressors (CM1, CM2, CM3),
wherein the at least three compressors (CM1, CM2, CM3) are started and stopped in the oil equalization mode such that one of the at least three compressors (CM1, CM2, CM3) at a time is stopped or operated at a low load while the others of the at least three compressors (CM1, CM2, CM3) are operated, wherein the at least three compressors (CM1, CM2, CM3) comprise a first compressor (CM1) and a second compressor (CM2),
wherein, a controller controls the second compressor (CM2), which is stopped or in low-load operation, to begin starting up before the first compressor (CM1), which is in operation but is to be stopped or operated in a low-load condition, reaches low-load operation or is completely stopped, and
the controller (10) controls the starting and stopping of each of the at least three compressors (CM1, CM2, CM3) so that the operation of starting up the second compressor (CM2) is completed at the same time as when the first compressor (CM1) is stopped or completes the transition to low-load operation.

Ansprüche

1. Außeneinheit (10), die mindestens drei Verdichter (CM1, CM2, CM3) umfasst,
wobei die Außeneinheit mit einer Ölausgleichsmodus-Funktion konfiguriert ist, die dafür konfiguriert ist, einen ordnungsgemäßen Ölstand in jedem der Verdichter (CM1, CM2, CM3) aufrecht zu erhalten,
wobei die Außeneinheit (10) dadurch gekennzeichnet ist, dass sie eine Steuereinheit (12) umfasst, die dafür konfiguriert ist, das Starten und Stoppen der Verdichter (CM1, CM2, CM3) in dem Ölausgleichsmodus so zu steuern, dass einer der mindestens drei Verdichter (CM1, CM2, CM3) auf einmal gestoppt oder mit einer geringen Last betrieben wird, während sie dafür konfiguriert ist, die anderen der mindestens drei Verdichter (CM1, CM2, CM3) zu veranlassen zu arbeiten, wobei die mindestens drei Verdichter (CM1, CM2, CM3) einen ersten Verdichter (CM1) und einen zweiten Verdichter (CM2) umfassen,
wobei die Steuereinheit (12) dafür konfiguriert ist, während des Ölausgleichsmodus den zweiten Verdichter (CM2), der gestoppt ist oder in einem Niedriglastbetrieb arbeitet, zu veranlassen anzulaufen, bevor der erste Verdichter (CM1), der in Betrieb ist, aber angehalten werden oder in einem Niedriglastbetrieb arbeiten soll, den Niedriglastbetrieb erreicht oder vollständig anhält, und
die Steuereinheit (12) dafür konfiguriert ist, das Starten und Stoppen jedes der mindestens drei Verdichter (CM1, CM2, CM3) so zu steuern, dass der Vorgang des Anlaufens des zweiten Verdichters (CM2) im selben Moment vollendet ist, wo der erste Verdichter (CM1) anhält oder den Übergang zum Niedriglastbetrieb vollendet.

2. Klimatisierungsvorrichtung vom Mehrfachtyp, die die Außeneinheit (10) nach Anspruch 1 umfasst.

3. Verfahren zum Betreiben einer Außeneinheit (10), die mindestens drei Verdichter (CM1, CM2, CM3) enthält und eine Ölausgleichsmodus-Funktion hat, um einen ordnungsgemäßen Ölstand in jedem der Verdichter (CM1, CM2, CM3) aufrecht zu erhalten,
wobei die mindestens drei Verdichter (CM1, CM2, CM3) in dem Ölausgleichsmodus so gestartet und gestoppt werden, dass einer der mindestens drei Verdichter (CM1, CM2, CM3) auf einmal gestoppt oder mit einer geringen Last betrieben wird, während die anderen der mindestens drei Verdichter (CM1, CM2, CM3) arbeiten, wobei die mindestens drei Verdichter (CM1, CM2, CM3) einen ersten Verdichter (CM1) und einen zweiten Verdichter (CM2) umfassen,
wobei eine Steuereinheit den zweiten Verdichter (CM2), der gestoppt ist oder in einem Niedriglastbetrieb arbeitet, veranlasst anzulaufen, bevor der erste Verdichter (CM1), der in Betrieb ist, aber angehalten werden oder in einem Niedriglastbetrieb arbeiten soll, den Niedriglastbetrieb erreicht oder vollständig anhält, und
die Steuereinheit (10) das Starten und Stoppen jedes der mindestens drei Verdichters (CM1, CM2, CM3) so steuert, dass der Vorgang des Anlaufens des zweiten Verdichters (CM2) im selben Moment vollendet ist, wo der erste Verdichter (CM1) anhält oder den Übergang zum Niedriglastbetrieb vollendet.

Revendications

1. Unité extérieure (10) comportant au moins trois compresseurs (CM1, CM2, CM3), l'unité extérieure étant configurée avec une fonction de mode d'égalisation d'huile configurée pour maintenir un niveau d'huile correct dans chacun des compresseurs (CM1, CM2, CM3),
l'unité extérieure (10) étant caractérisée en ce qu'elle comporte un dispositif de commande (12) configuré pour commander le démarrage et l'arrêt des compresseurs (CM1, CM2, CM3) dans le mode d'égalisation d'huile de telle sorte qu'un des au moins trois compresseurs (CM1, CM2, CM3) à la fois est arrêté ou amené à fonctionner à une faible charge tout en étant configuré pour amener l'autre des au moins trois compresseurs (CM1, CM2, CM3) à fonctionner, les au moins trois compresseurs (CM1, CM2, CM3) comportant un premier compresseur (CM1) et un deuxième compresseur (CM2),
dans laquelle, pendant le mode d'égalisation d'huile, le dispositif de commande (12) est configuré pour amener le deuxième compresseur (CM2), qui est arrêté ou dans un fonctionnement à faible charge, à commencer à démarrer avant que le premier compresseur (CM1), qui est en fonctionnement mais doit être arrêté ou amené à fonctionner dans une condition de faible charge, atteigne un fonctionnement à faible charge ou soit complètement arrêté, et
le dispositif de commande (12) est configuré pour commander le démarrage et l'arrêt de chacun des au moins trois compresseurs (CM1, CM2, CM3) de telle sorte que l'opération de démarrage du deuxième compresseur (CM2) est terminée en même temps que quand le premier compresseur (CM1) est arrêté ou termine le passage au fonctionnement à faible charge.

2. Climatiseur de type multiple comportant l'unité extérieure (10) selon la revendication 1.

3. Procédé de mise en oeuvre d'une unité extérieure (10) comprenant au moins trois compresseurs (CM1, CM2, CM3) et ayant une fonction de mode d'égalisation d'huile pour maintenir un niveau d'huile correct dans chacun des compresseurs (CM1, CM2, CM3),
selon lequel les au moins trois compresseurs (CM1, CM2, CM3) sont démarrés et arrêtés dans le mode d'égalisation d'huile de telle sorte qu'un des au moins trois compresseurs (CM1, CM2, CM3) à la fois est arrêté ou amené à fonctionner à une faible charge tandis que les autres des au moins trois compresseurs (CM1, CM2, CM3) fonctionnent, les au moins trois compresseurs (CM1, CM2, CM3) comportant un premier compresseur (CM1) et un deuxième compresseur (CM2),
selon lequel un dispositif de commande commande le deuxième compresseur (CM2), qui est arrêté ou dans un fonctionnement à faible charge, pour commencer à démarrer avant que le premier compresseur (CM1), qui est en fonctionnement mais doit être arrêté ou amené à fonctionner à faible charge, atteigne un fonctionnement à faible charge ou soit complètement arrêté, et le dispositif de commande (10) commande le démarrage et l'arrêt de chacun des au moins trois compresseurs (CM1, CM2, CM3) de telle sorte que l'opération de démarrage du deuxième compresseur (CM2) est terminée en même temps que quand le premier compresseur (CM1) est arrêté ou termine le passage au fonctionnement à faible charge.

Drawing