JPH025323Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a heat pump type separate air conditioner that can switch a plurality of indoor units to correspond to a single outdoor unit individually and alternately. In particular, the present invention relates to a separate air conditioner that can reduce heat loss as much as possible during heating operation and improve startup characteristics. [Technical background of the invention and its problems] In general, the refrigeration cycle of a heat pump type separate air conditioner is such that one outdoor unit corresponds to multiple indoor units, and the units are switched and operated one by one. is constructed as shown in FIG. The outdoor unit a is provided with a compressor b, an outdoor heat exchanger c, an expansion valve d, and a four-way valve e, and correspondingly, a plurality of (two in the illustrated example) indoor units f, g are provided with indoor heat exchangers h and i each having the same heat exchange capacity. The capacity of this outdoor unit a corresponds to one indoor unit f, g, and a plurality of indoor units f, g are not operated at the same time. Therefore, a switching unit j is interposed between the indoor and outdoor units a, f, and g for alternately selecting and switching the operating indoor units f and g. In the switching unit J, on-off switching valves k, l, m,
n and check valves o, p, q, and r are provided. The outdoor unit a and the switching unit j are connected by connections s and t, and the switching unit j and the indoor units f and g are connected by connecting pipes u, v, w, and x, respectively, to form a refrigeration cycle. ing. Here, the circulation paths of the refrigerant in the conventional circuit described above are indicated by the above symbols in the order in which they pass. Note that the indoor heat exchanger through which the refrigerant passes is underlined. B. When operating indoor unit f for cooling. As for on/off switching valves k, l, m, and n, l is open, k,
m and n are closed. Refrigerant circulation path: b→e→c→d→s→p→
l → v → h → u → r → t → e → b b When operating indoor unit g for air conditioning. In the on-off switching valve, n is open, and k, l, and m are closed. Refrigerant circulation path: b→e→c→d→s→p→
n→x→ i →w→r→t→e→b c. When heating indoor unit f. As for the on-off switching valves, k and n are open, and l and m are closed. Refrigerant circulation path: b→e→t→q→n→x→
i→w→u→ h →v→k→o→s→d→c→e
→b Note that although not shown in the figure, indoor unit f is ON and indoor unit g is OFF. D. When indoor unit g is operated for heating. On-off switching valves l and m are open, and k and n are closed. Refrigerant circulation path: b→e→t→q→l→v→
h→u→w→ i →x→m→o→s→d→c→e
→b Regarding the indoor fan, indoor unit g is ON and indoor unit f is OFF. By the way, when comparing the refrigerant circulation paths in cooling operation and heating operation,
In the case of cooling operation, the refrigerant flows through the indoor heat exchanger of the operated indoor unit and does not flow to the indoor heat exchangers of other indoor units. However, in the case of heating operation, although only one indoor unit is in operation, the air is configured to flow through the indoor heat exchangers of all indoor units. That is, in the case of cooling operation, the indoor heat exchanger acts as an evaporator, so the refrigerant exists in the heat exchanger in a gaseous state, and the amount of refrigerant distributed in the entire refrigeration cycle is relatively small. At the same time, since the refrigerant is located on the lower pressure side than the expansion valve, even if the indoor unit is switched, the refrigerant in the stopped indoor unit can be naturally recovered to the low pressure side of the compressor when left unattended. However, in the case of heating operation, the indoor heat exchanger acts as a condenser, so the refrigerant is present in the heat exchanger in liquid form, and the amount of refrigerant distributed above is relatively large and is located on the high pressure side of the expansion valve. ing. Therefore, when switching the operating indoor unit, it is necessary to actively apply pressure to the refrigerant in the stopped indoor unit from the high pressure side to the low pressure side and recover it to the low pressure side of the compressor. It consists of a refrigeration cycle. In this way, during heating operation, the refrigerant is constantly flowing even to the indoor units that are stopped, so the heat radiation in the indoor heat exchanger becomes wasteful heat exchange and becomes a factor that increases heat loss. There was also the problem that the indoor unit being operated was slow to start up. [Purpose of the invention] The present invention has been devised in view of the above-mentioned problems and to effectively solve them. The purpose of this invention is to reduce heat loss during heating operation as much as possible in a heat pump type separate air conditioner that can switch multiple indoor units to correspond to a single outdoor unit. An object of the present invention is to provide a separate air conditioner that can reduce the rise in temperature and improve the rise characteristics. [Summary of the invention] This invention configures the refrigerant circuit independently for each indoor unit operated during heating operation, and provides a bypass circuit that can recover the refrigerant remaining in the indoor unit that is shut down to the low pressure side of the compressor. The above object is achieved by forming the above object. [Embodiment of the invention] A preferred embodiment of the invention will be described below with reference to the accompanying drawings. FIG. 2 shows the circuit configuration of the refrigeration cycle of the separate air conditioner according to the present invention. 1 is an outdoor unit, and correspondingly there are a plurality of (two in the illustrated example) indoor units 2,
3 are provided in parallel. A switching unit 4 is interposed between the outdoor unit 1 and the indoor units 2 and 3, and is operated to alternately switch the indoor units to be operated. The outdoor unit 1 is provided with a compressor 5, an outdoor heat exchanger 6, an expansion valve 7 as a first pressure reducing device, and a four-way valve 8 as an air conditioning circuit switching valve. A first bypass circuit 10 is formed via the on-off valve 9. The indoor units 2 and 3 are provided with indoor heat exchangers 11 and 12, respectively. The switching unit 4 is provided with outdoor connection circuits 13, 14 connected to the indoor unit 1 side, and indoor connection circuits 15, 16, 17, 18 branched from these and connected to the indoor units 2, 3, respectively. There is. In addition, each indoor side connection circuit 15,
On-off switching valves 19, 20, 21, and 22 are interposed in series at 16, 17, and 18 for switching over and opening a refrigeration cycle circuit to an operating indoor unit. During heating operation, the high pressure side of each connection circuit is 13, 15, 17, and the low pressure side is 14, 16, 18. Note that during cooling operation, the refrigerant circulates in the opposite direction, so 13, 15, and 17 are on the low pressure side, and 14,
16 and 18 are on the high pressure side. The low pressure side outdoor connection circuit 14 during heating operation has a second
An expansion valve 23 is provided as a pressure reducing device,
It is configured to detect the temperature of the high pressure side 13 and low pressure side 14 of the outdoor side connection circuit and adjust the throttle. In addition, the low pressure side indoor connection circuits 16 and 18 include
Second bypass circuits 24 and 25 are provided which are branched from the indoor units 2 and 3 sides of the respective on-off switching valves 20 and 22 and connected to the low pressure side of the expansion valve 23. These second bypass circuits 24, 25
Capillary tubes 26 and 27 are provided in series as third pressure reducing devices, respectively, and check valves 28 and 29 that allow refrigerant to flow only from the indoor connection circuits 16 and 18 to the outdoor connection circuit 14 are provided. It is provided. Next, the operation of the present invention will be explained. In this explanation, the same method as in the explanation of the prior art is used to indicate the refrigerant circulation path with symbols in the order in which it passes, and the indoor heat exchanger is underlined. E. When operating indoor unit 2 for cooling. As for the on-off switching valves, 19 and 20 are open, and 21 and 22 are closed. Refrigerant circulation route: 5 → 8 → 6 → 10 → 9 → 1
4 → 23 → 20 → 16 → 11 → 15 → 19 → 1
3→8→5 Note that no flow of refrigerant occurs in the second bypass circuit 24 because the pressure on the indoor side connection circuit 16 side is lower than that on the outdoor side connection circuit 14 side. F. When operating indoor unit 3 for cooling. As for the on-off switching valves, 21 and 22 are open, and 19 and 20 are closed. Refrigerant circulation route: 5 → 8 → 6 → 10 → 9 → 1
4 → 23 → 22 → 28 → 12 → 17 → 21 → 1
3→8→5 Note that no refrigerant flow occurs in the second bypass circuit 25 because the pressure on the indoor side connection circuit 18 side is lower than that on the outdoor side connection circuit 14 side. G. When operating indoor unit 2 for heating. On-off switching valves 19 and 20 are open, and valves 21 and 22 are closed. Refrigerant circulation path: 5→8→13→19→15 → 11 →16〓20→23 24→26→28〓14→9 →10→6→8→5 Note that the capillary is smaller than the expansion valve 23. tube 2
6 is set to a large pressure loss, and most of the refrigerant passes through the on-off switching valve 20 and the expansion valve 23. In addition, if heating operation is being performed by the indoor unit 3 before heating the indoor unit 2, the on-off switching valves 21 and 22 are switched from open to closed, and the indoor heat exchanger 12 and the indoor connection are switched from open to closed. circuit 1
The refrigerant remaining in the indoor units 7 and 18 is recovered to the low-pressure side outdoor connection circuit 14 via the second bypass circuit 25 when the heating operation of the indoor unit 2 starts. H. When operating indoor unit 3 for heating. As for the on-off switching valves, 21 and 22 are open, and 19 and 20 are closed. Refrigerant circulation path: 5 → 8 → 13 → 21 → 17 → 12 → 18 〓 22 → 23 25 → 27 → 29 〓 14 → 9 → 10 → 6 → 8 → 5 As in the case of G, most refrigerants passes through the on-off valve 22 and the expansion valve 23. Furthermore, in the case of switching from the indoor unit 2, the refrigerant remaining on the indoor unit 2 side is similarly recovered to the low pressure side outdoor connection circuit 14 by the second bypass circuit 24. In addition, the outdoor unit 1 can be connected without going through the switching unit 4.
When connecting one indoor unit 2 or 3, the on-off valve 9 is closed and the expansion valve 7 is used to configure a refrigeration cycle. [Effects of the invention] As is clear from the above explanation, the invention provides the following effects. (1) During heating operation, the refrigerant does not flow through the indoor units that are stopped and circulates only through the indoor units that are being operated, so heat loss is reduced as much as possible. (2) In addition, when recovering the residual refrigerant in the indoor unit that has been stopped, the residual refrigerant does not flow into the indoor unit that is being operated, and the high pressure side of the compressor is always connected to the heat exchanger inside the operating room. As a result, the rise characteristics are improved. (3) Control of the on-off switching valve is simple and highly reliable. (4) It is possible to eliminate the noise of refrigerant flowing in indoor units that are stopped. (5) Since heat loss in stopped indoor units is reduced, the number of indoor units can be increased.

[Brief explanation of the drawing]

FIG. 1 is a refrigerant circuit diagram of a separate air conditioner according to a conventional example of the present invention, and FIG. 2 is a refrigerant circuit diagram showing an embodiment of the separate air conditioner according to the present invention. In the figure, 1 is an outdoor unit, 2 and 3 are indoor units, 4 is a switching unit, 5 is a compressor, 6 is an outdoor heat exchanger, 7 is a first pressure reducing device exemplified by an expansion valve, and 8 is a four-way unit. Heating and cooling circuit switching valve illustrated as a valve, 9
is an on-off valve, 10 is a first bypass circuit, 11,1
2 is an indoor heat exchanger, 13 and 14 are outdoor connection circuits, 15, 16, 17, and 18 are indoor connection circuits,
19, 20, 21, 22 are on-off switching valves, 23 is a second pressure reducing device exemplified by an expansion valve, 24, 25 is a second bypass circuit, and 26, 27 is a third pressure reducing device exemplified by a capillary tube. It is.

Claims (1)

[Claims for Utility Model Registration] For a single outdoor unit having a compressor, an outdoor heat exchanger, a first pressure reducing device, and an air conditioning circuit switching valve, a plurality of units each having an indoor heat exchanger In a separate air conditioner capable of performing cooling and heating operation by switching the indoor units so that they can be operated independently and alternately, a first bypass circuit is provided in the outdoor unit and has an on-off valve in parallel with the first pressure reducing device. and a switching unit which is interposed between the indoor and outdoor units and has an outdoor connection circuit connectable to the outdoor unit and an indoor connection circuit branched from the outdoor connection circuit so as to be connectable to each indoor unit. , an on-off switching valve installed in series with each of the indoor side connection circuits, a second pressure reducing device installed in series on the low pressure side of the outdoor side connection circuit during heating operation, and a second pressure reducing device installed in series on the low pressure side of the outdoor connection circuit during heating operation; At the time of unit switching, the refrigerant is bypassed from the low-pressure side of the indoor connection circuit to the low-pressure side of the second pressure reducing device, and the refrigerant accumulated in the stopped indoor unit is recovered to the low-pressure side of the outdoor unit. A separate air conditioner comprising a bypass circuit and a third pressure reducing device provided in series with each of the second bypass circuits.