WO2007139093A1

WO2007139093A1 - Freezing apparatus

Info

Publication number: WO2007139093A1
Application number: PCT/JP2007/060873
Authority: WO
Inventors: Satoru Sakae; Masaaki Takegami; Hiroto Nakajima; Iwao Shinohara
Original assignee: Daikin Industries, Ltd.
Priority date: 2006-05-31
Filing date: 2007-05-29
Publication date: 2007-12-06
Also published as: EP2023060A1; KR20090018971A; TW200809150A; JP2007322048A; CN101454623A; US20090229301A1; AU2007268608A1

Abstract

Provided is a freezing apparatus (1), which comprising first to third three compressors (11a, 11b and 11c) connected in parallel, and an oil separator for separating the freezer oil from the discharged coolant of the compressors (11a, 11b and 11c). A sucking main pipe (55), through which the sucked coolant of the compressors (11a, 11b and 11c) flows, is provided with a main curved portion (101) and a main branch portion (102) on the downstream side of the connected portion of an oil return pipe (71) for returning the freezer oil of the oil separator. The sucking main pipe (55) is branched at the main branch portion (102) into a first sucking branch pipe (61a) of the first compressor (11a) and a sucking connection pipe (56). At the main branch portion (102), the first sucking branch pipe (61a) is positioned at the lowest portion and at the outermost circumference portion with respect to the direction of the radius of curvature of the main curved portion (101).

Description

Specification

Refrigeration equipment

Technical field

[0001] The present invention relates to a refrigeration apparatus including a plurality of compressors connected in parallel.

Background art

[0002] Conventionally, some refrigeration apparatuses that perform a refrigeration cycle have a plurality of compressors connected in parallel in order to widely change the compressor capacity in accordance with operating conditions on the user side (for example, patents). Reference 1).

[0003] The refrigeration apparatus of Patent Document 1 includes an indoor unit that has an indoor heat exchanger and performs indoor air conditioning, a refrigeration unit that has a refrigerated heat exchanger and cools a refrigerated showcase, and a refrigeration heat exchanger. And a booster compressor for cooling the refrigeration showcase and an outdoor heat exchanger and an indoor unit having three compressors.

[0004] In the operation of performing only cooling of the refrigeration and refrigeration showcase, the refrigeration apparatus is in a state where the inverter compressor, which is the two compressors of the outdoor unit, and the first non-inverter compressor are connected in parallel. Driven. In this operation, the refrigerant discharged from the two compressors is condensed in the outdoor heat exchanger and distributed to the refrigeration unit and the refrigeration unit. The distributed refrigerant is expanded by each expansion valve for refrigeration and refrigeration, and then absorbs heat from the air in the showcase and evaporates by each heat exchanger to cool each showcase. Thereafter, the refrigerant that has flowed out of the refrigeration unit and the refrigerating unit joins and is introduced into the outdoor unit, flows through the suction main pipe, and then flows into the suction branch pipe of each compressor and is sucked into each compressor. .

[0005] In the refrigeration apparatus, an oil separator that separates refrigeration oil from the discharged refrigerant is provided in a discharge pipe where the discharged refrigerant of the two compressors joins! / Speak. The refrigerating machine oil separated by the oil separator is supplied to the suction main pipe through the oil return pipe, and is divided into each suction branch pipe and supplied to each compressor.

[0006] Each of the two compressors is connected to an oil equalizing pipe connected to the suction branch pipe of the other compressor at a predetermined height position of the dome. The oil equalizing pipe is provided with a solenoid valve. In the two compressors, the oil valves of each oil equalizing pipe are alternately opened at predetermined time intervals, for example. By entering the state, the refrigerating machine oil stored in the dome of one compressor is supplied to the other compressor via the oil equalizing pipe to perform oil equalization.

Patent Document 1: Japanese Patent Laid-Open No. 2004-353996

Disclosure of the invention

Problems to be solved by the invention

[0007] However, in the refrigeration apparatus of Patent Document 1 described above, since the refrigeration oil separated by the oil separator is simply returned to the suction main pipe, the reliability of the compressor with insufficient management of the refrigeration oil is reduced. There was a problem of doing.

[0008] The present invention has been made in view of the problem, and an object of the present invention is to perform sufficient oil management for a compressor in a refrigeration apparatus including a plurality of compressors connected in parallel. Means for solving the problem

[0009] The first invention separates a plurality of compressors (11a, l ib, 11c) connected in parallel to each other and the refrigerant refrigerant discharged from the compressors (11a, l ib, 11c). A refrigerant circuit (10) having an oil separator (70), and a refrigerant pipe of the refrigerant circuit (10) includes a suction main pipe (55) through which a suction refrigerant of the compressor (11a, ib, 11c) flows. , The refrigerant in the suction main pipe (55) is divided into the compressors (11a, l ib, 11c), the suction branch pipes (61a, 61b, 61c), and the refrigeration machine oil separated by the oil separator (70) And an oil return pipe (71) for returning the air to the suction main pipe (55), wherein the suction main pipe (55) is pre-set among the compressors (11a, ib, 11c). The main drift means (110) for drifting the refrigeration oil in the suction main pipe (55) is connected to the oil return pipe (71) so that a large amount of refrigeration oil flows in the suction branch pipe (61a) of the first compressor (11a). It is located downstream from the section.

[0010] That is, in the conventional refrigeration system, the refrigeration oil whose oil separator force has also returned to the suction main pipe has been unable to grasp the amount of return to each of the compressors connected in parallel. For this reason, in the oil leveling operation, an unnecessary operation is performed in which the solenoid valve of the oil leveling pipe is opened to level the compressor from the compressor with insufficient refrigeration oil in the dome to the compressor filled with refrigeration oil in the dome. Furthermore, due to this unnecessary operation, there has been a problem that the refrigerating machine oil cannot be quickly supplied to the compressor having a shortage of refrigerating machine oil. In other words, the conventional refrigeration system supplies the refrigeration oil to the compressor with a large amount of refrigeration oil or the compressor with a small amount of refrigeration oil through the oil equalizing pipe. Then, only proper oil leveling operation was performed, and unnecessary operations were also performed. Therefore, depending on the compressor, there was a risk that the refrigeration oil would always be short.

Therefore, in the first invention, a large amount of refrigerating machine oil flows to the intake branch pipe (61a) of the first compressor (11a) by the main drift means (110), and the plurality of compressors Of refrigeration oil (11a, 11b, 11c), return the refrigeration oil to the first compressor (11a) as much as possible. Thus, the refrigeration oil is reliably stored in the dome of the first compressor (11a), and the refrigeration oil is supplied from the first compressor (11a) to the other compressors (lib, 11c). Do proper oil leveling.

[0012] The second invention separates a plurality of compressors (11a, l ib, 11c) connected in parallel to each other and refrigerant discharged from the compressors (11a, l ib, 11c). Refrigerating machine oil A refrigerant circuit (10) having an oil separator (70), and a refrigerant pipe of the refrigerant circuit (10) includes a suction main pipe (55) through which a suction refrigerant of the compressor (11a, ib, 11c) flows. , The refrigerant in the suction main pipe (55) is divided into the compressors (11a, l ib, 11c), the suction branch pipes (61a, 61b, 61c), and the refrigeration machine oil separated by the oil separator (70) A refrigerating apparatus including an oil return pipe (71) for returning the air to the suction main pipe (55), wherein the suction main pipe (55) is sucked into the main curved portion (101) and the suction main pipe (55). A main branch part (102) from which the branch pipes (61a, 61b, 61c) branch is provided in order downstream from the connection part of the oil return pipe (71). In the main branch part (102), Of the first compressor (11a) set in advance among the compressors (11a, l ib, 11c) Input branch pipe (61a) is located in the outermost peripheral portion against the curvature radius direction of the main curved section (101), Ru.

[0013] In the second invention, centrifugal force acts when the refrigerant and the refrigerating machine oil flow through the main curved portion (101) of the suction main pipe (55), and the main curved section (101 of the suction main pipe (55) ), The refrigerant flows inward with respect to the radius of curvature of the main curved portion (101) due to the centrifugal force difference between the refrigerant and the refrigeration oil, while the refrigeration oil flows in the main curved portion (101). Flows outside in the radius direction of curvature. In the main branch portion (102), the suction branch pipe (6 la) of the first compressor (11a) is located on the outermost peripheral portion in the radius direction of curvature of the main curved portion (101). ) Refrigeration machine oil flowing outside the pipe flows into the suction branch pipe (61a) of the first compressor (11a). In this way, the refrigeration oil is returned to the first compressor (11a) among a plurality of compressors (11a, ib, 11c), and the force of the first compressor (11a) is also reduced to other compressors ( l Supply refrigeration oil to ib, 11c) Use proper oil leveling.

[0014] The third invention separates a plurality of compressors (11a, l ib, 11c) connected in parallel to each other and the refrigerant refrigerant discharged from the compressors (11a, l ib, 11c) A refrigerant circuit (10) having an oil separator (70), and a refrigerant pipe of the refrigerant circuit (10) includes a suction main pipe (55) through which a suction refrigerant of the compressor (11a, ib, 11c) flows. , The refrigerant in the suction main pipe (55) is divided into the compressors (11a, l ib, 11c), the suction branch pipes (61a, 61b, 61c), and the refrigeration machine oil separated by the oil separator (70) A refrigerating apparatus including an oil return pipe (71) for returning the suction main pipe (55) to a main branch section (61a, 61b, 61c) branching from the suction main pipe (55) ( 102), the suction branch pipe (61a) of the first compressor (11a) set in advance among the compressors (11a, ib, 11c) is located at the lowermost part.

In the third invention, in the suction main pipe (55), due to the difference in gravity between the refrigerant and the refrigeration oil, the refrigerant flows upward while the refrigeration oil flows downward. In the main branch section (102), since the suction branch pipe (61a) of the first compressor (11a) is located at the lowermost part, the refrigeration flowed below the suction main pipe (55) Machine oil flows into the suction branch pipe (61a) of the first compressor (11a). As described above, the refrigeration oil is returned to the first compressor (1 la) among the plurality of compressors (11a, ib, 11c), and the first compressor (1 la) to another compressor. (1 lb, 11c), supply refrigeration oil, and perform proper oil leveling.

[0016] A fourth invention separates a plurality of compressors (11a, l ib, 11c) connected in parallel to each other and refrigerant discharged from the compressors (11a, l ib, 11c). Refrigerating machine oil A refrigerant circuit (10) having an oil separator (70), and a refrigerant pipe of the refrigerant circuit (10) includes a suction main pipe (55) through which a suction refrigerant of the compressor (11a, ib, 11c) flows. , The refrigerant in the suction main pipe (55) is divided into the compressors (11a, l ib, 11c), the suction branch pipes (61a, 61b, 61c), and the refrigeration machine oil separated by the oil separator (70) A refrigerating apparatus including an oil return pipe (71) for returning the air to the suction main pipe (55), wherein the suction main pipe (55) is sucked into the main curved portion (101) and the suction main pipe (55). A main branch part (102) from which the branch pipes (61a, 61b, 61c) branch is provided in order downstream from the connection part of the oil return pipe (71). In the main branch part (102), Of the first compressor (11a) set in advance among the compressors (11a, l ib, 11c) Input branch pipe (61a) is located in the outermost peripheral portion against the curvature radius direction of and the main bay curved portion at the bottom (101), Ru. That is, the fourth invention is the second invention, wherein the suction branch pipe (6 la) of the first compressor (11a) is located at the lowermost part of the main branch part (102), The

[0018] In the fourth aspect of the invention, the refrigerant and the refrigerating machine oil flow through the suction main pipe (55), and the centrifugal force by the gravity and the main bending portion (101) acts, so that the main bending portion of the suction main pipe (55). On the downstream side of (101), the refrigerant flows upward and inward with respect to the radius direction of curvature of the main curved portion (101), while the refrigerating machine oil is below and relative to the radius of curvature of the main curved portion (101). Flowing outside. In the main branch portion (102), the suction branch pipe (61a) of the first compressor (11a) is located at the lowermost portion and the outermost peripheral portion in the radius of curvature direction of the main curved portion (101). Therefore, the refrigerating machine oil flowing below and outside the suction main pipe (55) flows into the suction branch pipe (61a) of the first compressor (11a). In this way, the refrigeration oil is returned to the first compressor (1 la) among a plurality of compressors (11a, l ib, 11c), and another compression is performed from the first compressor (1 la). Properly level the oil by supplying refrigeration oil to the machine (1 lb, 11c).

[0019] In a fifth aspect based on the first aspect, the plurality of compressors (11a, l ib, 11c) also has the first to third compressors (11a, l ib, 11c) force. The suction main pipe (55) is configured to have a suction connection pipe (61b) branched into a suction branch pipe (61b) of the second compressor (l ib) and a suction branch pipe (61c) of the third compressor (11c). 56) and the suction branch pipe (61a) of the first compressor (11a), and the refrigeration oil flowing through the suction connection pipe (56) flows into the suction branch pipe (3c) of the third compressor (11c). Sub-current drift means (120) for drifting the refrigeration machine oil in the suction connection pipe (56) is provided so as to flow more to the suction branch pipe (61b) of the second compressor (lib) than 61c).

[0020] In the fifth aspect of the invention, the sub-drift means (120) causes the second compressor (l ib) to receive the second refrigerator oil among the three compressors (11a, l ib, 1 lc). Try to return a lot. In this way, in the three compressors (11a, l ib, 11c), the refrigeration oil is returned in the order of the first, second, and third compressors, and the compressor (11a, l ib) Supply the refrigerating machine oil to the compressor with low refrigerating machine oil (l ib, 11c) and perform appropriate oil leveling.

[0021] A sixth invention is the invention according to any one of the second to fourth inventions, wherein the plurality of compressors (11a, 11b, 11c) are the first to third three compressors (11a, l ib, 11c) force is also configured, and the suction main pipe (55) is connected to the suction branch pipe (61b) of the second compressor (l ib) and the third compressor (11c) at the main branch (102). Suction connection pipe (104) with a sub-branch (104) that branches into the suction branch pipe (61c) 56) and a suction branch pipe (61a) of the first compressor (11a). The suction connection pipe (56) is provided with a sub-curved portion (103), and the sub-branch portion (104 ), The suction branch pipe (61b) of the second compressor (I ib) is more in the radial direction of curvature of the sub-curved portion (10 3) than the suction branch pipe (61c) of the third compressor (11c). Located on the outside.

[0022] In the sixth aspect of the invention, centrifugal force acts when the refrigerant and the refrigerating machine oil flow through the auxiliary curved portion (103) of the suction connection pipe (56). Thus, on the downstream side of the sub-curved portion (103) of the suction connection pipe (56), the refrigerant is displaced with respect to the curvature radius direction of the sub-curved portion (103) due to the difference in centrifugal force acting on the refrigerant and the refrigerating machine oil. Flows inside, while refrigeration oil flows outside. Then, in the sub-branch portion (104), the suction branch pipe (61b) of the second compressor (l ib) is sub-curved part (61c) than the suction branch pipe (61c) of the third compressor (1 lc). Since it is located outside the radius of curvature of 103), the refrigeration oil in the suction connection pipe (56) returns more to the second compressor (l ib) than to the third compressor (11c). In this way, in the three compressors (11a, ib, 11c), the refrigeration oil returns in the order of the first, second, and third compressors, and the compressors (11a, 11 Supply the refrigerating machine oil from b) to the compressor (lib, 11c) with a small quantity of refrigerating machine oil and perform appropriate oil leveling

[0023] In a seventh aspect based on any one of the second to fourth aspects, the plurality of compressors (11a, 11b, 11c) includes the first to third three compressors (11a, l ib, 11c) force is also constructed,

55) is a sub-branch section that branches into the suction branch pipe (61b) of the second compressor (l ib) and the suction branch pipe (61c) of the third compressor (11c) in the main branch section (102). 104) suction connection pipe (

56) and a suction branch pipe (61a) of the first compressor (11a), and a suction branch pipe (1 lb) of the second compressor (1 lb) 61b) is located below the intake branch (61c) of the third compressor (1 lc).

In the seventh aspect of the invention, when the refrigerant and the refrigerating machine oil flow through the suction connection pipe (56), the refrigerant flows upward due to the difference in gravity between the refrigerant and the refrigerating machine oil, while the refrigerating machine oil flows downward. It flows. In the sub-branch portion (104), the suction branch pipe (61b) of the second compressor (l ib) is positioned below the suction branch pipe (61c) of the third compressor (11c). Therefore, the refrigeration oil in the suction connection pipe (56) returns more to the second compressor (l ib) than to the third compressor (11c). In this way, in the three compressors (11a, ib, 11c), the refrigerators in the order of the first, second, and third compressors. Make sure that the oil returns a lot, and supply the compressor oil to the compressors (l ib, 11c) with low refrigerating machine oil (11a, l ib) and perform appropriate oil leveling.

[0025] According to an eighth invention, in any one of the second to fourth inventions, the plurality of compressors (11a, 11b, 11c) includes the first to third three compressors (11a, l ib, 11c) force is also constructed,

56) and a suction branch pipe (61a) of the first compressor (11a). The suction connection pipe (56) is provided with a sub-curved portion (103), and the sub-branch portion (104 ), The suction branch pipe (61b) of the second compressor (I ib) is below the suction branch pipe (61c) of the third compressor (11c) and the radius direction of curvature of the sub-curved portion (103) It is located on the outside.

[0026] In other words, in an eighth aspect based on the sixth aspect, the suction branch pipe of the second compressor (lib)

(61b) is positioned below the suction branch pipe (61c) of the third compressor (1 lc) in the sub-branch portion (104).

In the eighth aspect of the invention, the refrigerant and the refrigerating machine oil flow through the suction connection pipe (56), and the gravity and the centrifugal force in the sub-curvature portion (103) act. On the downstream side of the curved portion (103), the refrigerant flows upward and inward with respect to the radius of curvature of the sub-curved portion (103), while the refrigerating machine oil is below and in the radius of curvature of the sub-curved portion (103). Against the outside. In the sub-branch portion (104), the suction branch pipe (61b) of the second compressor (lib) is below the suction branch pipe (61c) of the third compressor (11c) and is sub-curved. Therefore, the refrigerating machine oil in the suction connection pipe (56) is more in the second compressor (lib) than in the third compressor (11c). Return. In this way, in the three compressors (11a, l ib, 11c), the refrigeration oil returns in the order of the first, second, and third compressors, and the compressors (11a, l ib) Supply the refrigerating machine oil to the compressor with low refrigerating machine oil (l ib, 11c) and perform appropriate oil leveling.

[0028] In a ninth aspect based on the second or fourth aspect, the plurality of compressors (11a, l ib, 11c) includes the first to third compressors (11a, l ib, 11c) force is also configured, and the suction main pipe (55) is connected to the suction branch pipe (61b) of the second compressor (lib) and the suction branch pipe of the third compressor (11c) at the main branch (102). A suction connection pipe (56) having a sub-branch (104) branching into (61c); Branching to the suction branch pipe (61a) of the first compressor (11a), V to the sub-branch part (104), and the suction branch pipe (61b) of the second compressor (1 lb) Is located outside the suction branch pipe (61c) of the third compressor (1 lc) with respect to the radius of curvature of the main curved portion (101) of the suction main pipe (55).

In the ninth aspect of the invention, the refrigerant flowing through the suction connection pipe (56) and the refrigerating machine oil have a difference in centrifugal force in the main curved portion (101) of the suction main pipe (55). ), The refrigerant flows inward with respect to the radius of curvature of the main curved portion (101), while the refrigerating machine oil flows in the outer side. In the sub-branch section (104), the suction branch pipe (61b) of the second compressor (l ib) is more than the suction branch pipe (61c) of the third compressor (1 lc). (55) Since the main curved portion (101) is located on the outer side with respect to the radius of curvature, the refrigerating machine oil in the suction connection pipe (56) is more compressed in the second compressor than in the third compressor (11c). Return a lot to (l ib). In this way, in the three compressors (11a, l ib, 11c), the refrigeration oil is returned in the order of the first, second, and third compressors. Supply refrigeration oil to a compressor with low refrigeration oil and perform appropriate oil leveling.

[0030] A tenth invention is the invention according to any one of the first to ninth inventions, wherein the refrigeration oil stored in the dome of the first compressor (11a) is supplied to another compressor (lib, 11c). Oil leveling means (72, 73) for supplying to

[0031] In the tenth aspect of the invention, the refrigeration oil stored in the dome of the first compressor (11a) by the oil leveling means (72, 73) is supplied to the refrigeration oil by the first compressor (11a). Supply to other compressors (l ib, 11c) with a small return amount and perform appropriate oil leveling.

[0032] An eleventh invention according to any one of the first to tenth inventions is the compressors (11a, l ib) described above.

, 11c) is equipped with oil leveling means (72, 73, 74) for leveling the refrigerating machine oil stored in the dome.

[0033] In the eleventh invention, the oil leveling means (72, 73, 74) equalizes the refrigerating machine oil stored in the dome of the compressors (11a, 11b, 11c).

[0034] The twelfth invention is the fifth, eighth and ninth inventions, the twentieth invention is the sixth invention, and the twenty-first invention is the seventh invention. 1 Refrigerating machine oil stored in the dome of the compressor (11a) is sucked into the suction connecting pipe (56) or the second compressor (lib). The first oil leveling pipe (72) for supplying to the branch pipe (61b) and the refrigerating machine oil stored in the dome of the second compressor (lib) are connected to the suction branch pipe (3c) of the third compressor (11c). Supply the second oil leveling pipe (73) for supply to 61c) and the refrigeration oil stored in the dome of the third compressor (11c) to the suction main pipe (55) or the oil return pipe (71). A third oil leveling pipe (74) is provided!

[0035] In the twelfth, twentieth and twenty-first aspects of the present invention, the second compression in which the refrigerating machine oil returns to the next highest level through the first oil equalizing pipe (72) from the first compressor (11a) in which the refrigerating machine oil returns most Refrigeration oil is supplied to the compressor (l ib), and the refrigeration oil is reliably stored in the second compressor (lib). In this way, since the refrigeration oil is reliably stored also in the second compressor (lib), the refrigeration oil is the most from the second compressor (lib) by the second oil equalizing pipe (73). Supply refrigeration oil to the third compressor (11c), which is difficult to return, and ensure that the refrigeration oil is also stored in the third compressor (11c). The surplus of refrigeration oil in the third compressor (11c) is returned to the first compressor (11a).

[0036] In a thirteenth aspect based on any one of the first to twelfth, twentieth, and twenty-first aspects, the first compressor (11a) is a compressor (11a) having a fixed operating capacity.

[0037] That is, if the first compressor (11a) is configured to have a variable capacity, the first compressor (11a) can be connected to the first compressor (11a) even if it flows through the suction branch pipe (61a) of the first compressor (11a). The return amount of the refrigerating machine oil varies as the operating capacity of the first compressor (11a) varies. Therefore, in the thirteenth aspect of the invention, by fixing the operating capacity of the first compressor (11a), the first compressor (11a) can be reliably refrigerated during operation of the first compressor (11a). Return a lot of machine oil. Similarly, in the fifth to ninth inventions, if one of the second compressor (lib) and the third compressor (11c) has a fixed capacity and the other has a variable capacity, the second compressor ( l ib) is fixed.

[0038] In a fourteenth aspect based on any one of the first to thirteenth, twentieth and twenty-first aspects, each of the compressors (11a, ib, 11c) has a refrigerating machine oil in a high-pressure space in the dome. It is configured to store.

[0039] Here, in the low-pressure dome type compressor, since the refrigeration oil is stored in the low-pressure space of the compressor, the dome (oil storage part) is directly connected by an oil equalizing pipe. Oil can be done. In that case, the low-pressure dome type compressor can perform the oil leveling appropriately regardless of the return amount of the refrigeration oil of each compressor. [0040] On the other hand, high pressure dome type compressors and high and low pressure dome type compressors store refrigeration oil in the high pressure space inside the dome, so the compressor (11a, ib, 11c) In order to perform proper oil leveling, each compressor is only supplied by supplying refrigerating machine oil to the suction branch pipes (61a, 61b, 61c) of other compressors (11a, l ib, 11c). It is highly necessary to adjust the return amount of refrigeration oil (11a, l ib, 11c). Therefore, in the fourteenth aspect, the compressors (1 la, ib, 11c) are compressors (11a, ib, 11c) in which refrigeration oil is stored in a high-pressure space.

[0041] The fifteenth aspect of the invention is the suction branch pipe (61a, 61b, 61c) of each of the compressors (11a, lib, 11c) according to any of the first to fourteenth, twentieth and twenty-first aspects of the invention. Each of the liquid injection pipes (86, 86a) leads a part of the liquid refrigerant flowing in the liquid pipe (84) on the high pressure side in the refrigerant circuit (10) to the intake branch pipes (61a, 61b, 61c). , 86b, 86c) are connected.

[0042] That is, when liquid refrigerant is injected into the suction main pipe (55), the liquid refrigerant dissolves in the refrigeration oil and is supplied to the suction branch pipe (61a) of the first compressor (11a), and is supplied to the other compressors. It is difficult to supply to the suction branch pipe (61b) of the machine (l lb, 11c). Therefore, in the fifteenth aspect of the invention, the liquid refrigerant is individually injected into each intake branch pipe (61a, 61b, 61c) by the liquid injection pipe (86, 86a, 86b, 86c).

[0043] A sixteenth aspect of the present invention is directed to any one of the first to fifteenth, twentieth, and twenty-first aspects of the invention, wherein the intake branch pipe (61a, 61b, 61c) of each of the compressors (11a, ib, 11c) And oil recovery pipes (75, 76, 77) having one end connected to each other and the other ends connected to each other.

[0044] Here, since the refrigerating machine oil separated by the oil separator (70) is returned to the suction main pipe (55), if any compressor (11a) stops, the stopped compressor (11a ) Refrigerating machine oil also accumulates in the intake branch pipe (61a). In particular, when the first compressor (11a) is stopped most among a plurality of compressors, a large amount of refrigeration oil is placed in the suction branch pipe (61a) of the first compressor (11a). It will stay.

Accordingly, in the sixteenth aspect of the invention, the compressor (l ib, 11c) in operation is connected to the suction branch of the compressor (11a) being stopped via the oil recovery pipe (75, 76, 77). Refrigerating machine oil staying in the pipe (61a) is sucked. As a result, the stopped compressor (11a) does not suck a large amount of refrigeration oil when it is restarted.

[0046] A seventeenth aspect of the present invention is a plurality of compressors (11a, l ib, 11c) connected in parallel to each other, and the pressures A refrigerant circuit (10) having an oil separator (70) that separates refrigeration oil, while the refrigerant pipe of the refrigerant circuit (10) includes a compressor The suction main pipe (55) through which the suction refrigerant of (11a, l ib, 11c) flows, and the suction branch pipes (61a, 61b) that branch the refrigerant of the suction main pipe (55) to the compressors (11a, l ib, 11c) , 61c) and an oil return pipe (71) for returning the refrigeration machine oil separated by the oil separator (70) to the suction main pipe (55), wherein the compressors (11a, ib, 11c) is provided with oil recovery pipes (75, 76, 77) having one end connected to the suction branch pipe (61a, 61b, 61c) and the other end connected to each other.

[0047] That is, since the refrigerating machine oil separated by the oil separator (70) is returned to the suction main pipe (55), if any compressor (11a) stops, the stopped compressor (11a) Refrigerating machine oil and refrigerant stay in the intake branch pipe (61a).

Therefore, in the seventeenth aspect of the invention, the compressor (l ib, 11c) in operation is connected to the suction branch of the compressor (11a) being stopped via the oil recovery pipe (75, 76, 77). Refrigerating machine oil staying in the pipe (61a) is sucked. As a result, the stopped compressor (11a) does not suck a large amount of refrigeration oil when it is restarted.

[0049] The eighteenth invention is the sixteenth invention, and the nineteenth invention is the seventeenth invention, wherein the suction branch pipe (61a, 61b, 61c) is the suction branch pipe (61a , 61b, 61c), and an inclined portion (59) inclined upward from a predetermined position toward the downstream side, and an oil reservoir portion (58) formed on the upstream side of the inclined portion (59). One end of the oil recovery pipe (75, 76, 77) is connected to the oil reservoir (58).

[0050] In the eighteenth and nineteenth aspects of the present invention, the oil reservoir (58) of the intake branch pipe (61a, 61b, 61c) is lower than the inclined portion (59), so the compressor (11a, When l ib) stops, refrigeration oil stays in the oil reservoir (58). Since one end of the oil recovery pipe (75, 76, 77) is connected to the oil reservoir (58) of the intake branch pipe (61a, 61b, 61c), any compressor ( When 11a) is stopped, the operating compressor (l ib, 11c) is connected to the intake branch pipe (61a) of the stopped compressor (11a) via the oil recovery pipe (75, 76, 77). Make sure to inhale the refrigeration oil accumulated in the tank.

The invention's effect

[0051] According to the first invention, the main drift means (110) causes the plurality of compressors (11a , l ib, 11c), the refrigeration oil can be returned to the first compressor (11a) most, so that the refrigeration oil can be reliably stored in the dome of the first compressor (11a). As a result, the refrigeration oil of the first compressor (11a) can be distributed to the other compressors (l ib, 11c), so the oil management for each compressor (11a, l ib, 11c) can be performed accurately. Since this can be done, the reliability of each compressor (11a, l ib, 11c) is improved.

[0052] Further, according to the second invention, the first compressor (11a) is utilized by utilizing the difference in centrifugal force between the refrigerant and the refrigerating machine oil in the main curved portion (101) of the suction main pipe (55). ) Can return the largest amount of refrigerating machine oil, so that the refrigerating machine oil can be reliably stored in the dome of the first compressor (11a). As a result, the refrigeration oil of the first compressor (11a) can be distributed to the other compressors (l ib, 11c), so that the oil management for each compressor (11a, l ib, 11c) can be performed accurately. Since it can be performed, the reliability of each compressor (11a, ib, 11c) is improved.

[0053] Further, according to the third aspect of the invention, the first compressor (11a) is most preferably supplied with refrigerating machine oil by utilizing the difference in gravity between the refrigerant and the refrigerating machine oil flowing through the suction main pipe (55). Since a large amount can be returned, the refrigeration oil can be reliably stored in the dome of the first compressor (11a). As a result, the refrigeration oil of the first compressor (11a) can be distributed to the other compressors (l ib, 11c), so the oil management for each compressor (11a, l ib, 11c) Therefore, the reliability of each compressor (11a, l ib, 11c) is improved.

[0054] According to the fourth aspect of the invention, the gravity difference between the refrigerant and the refrigerating machine oil flowing through the suction main pipe (55) and the refrigerant in the main curved portion (101) of the suction main pipe (55) The maximum amount of refrigeration oil can be returned to the first compressor (11a) using the difference in centrifugal force with the refrigeration oil, so that the refrigeration oil is securely stored in the dome of the first compressor (11a). can do. As a result, the refrigeration oil of the first compressor (11a) can be distributed to the other compressors (l ib, 11c), so that the oil management for each compressor (11a, ib, 11c) can be accurately performed. Since this can be done, the reliability of each compressor (11a, l ib, 11c) is improved.

[0055] According to the fifth aspect of the invention, the three compressors are provided by the sub-drift means (120).

Since (11a, l ib, 11c) can return the second most refrigeration oil to the second compressor (l ib), the three compressors (11a, l ib, 11c) More refrigeration oil can be returned in the order of the second and third compressors. As a result, the compressor (11a, l ib) rich in refrigeration oil is cooled. Since the refrigeration oil can be supplied to the compressor (lib, 11c) with a small amount of refrigeration oil, each compressor (11a, ib, 11c) can be managed accurately. The reliability of (1 la, l ib, 11c) is improved.

[0056] According to the sixth aspect of the invention, the three compressors are utilized by utilizing the difference in centrifugal force between the refrigerant and the refrigerating machine oil in the sub-curved portion (103) of the suction connection pipe (56). (11a, l ib, 11c) Since the second most compressor oil can be returned to the second compressor (1 lb), the three compressors (11a, l ib, 11c) More refrigeration oil can be returned in the order of the second and third compressors. As a result, the compressor (11a, l ib) with a large amount of refrigeration oil can supply refrigeration oil to the compressor (l ib, 11c) with a small amount of refrigeration oil. Therefore, the reliability of each compressor (11a, l ib, 11c) is improved because the oil can be managed accurately.

[0057] Further, according to the seventh aspect of the invention, the three compressors (11a, ib, 11c) are utilized by utilizing the difference in gravity between the refrigerant flowing through the suction connection pipe (56) and the refrigerating machine oil. ), The second largest amount of refrigeration oil can be returned to the second compressor (l ib), so the three compressors (11a, l ib, 11c) have the first, second, third A lot of refrigeration oil can be returned in the order of the compressor. As a result, the compressor oil (11a, l ib) and the compressor with low refrigerator oil (l ib, 11c) can be supplied to the compressor (11a, l ib). Since the oil can be managed accurately for ib, 11c), the reliability of each compressor (11a, ib, 11c) is improved.

[0058] Further, according to the eighth aspect of the invention, the difference in gravity between the refrigerant and the refrigerating machine oil flowing through the suction connection pipe (56) and the difference in centrifugal force in the sub-curved portion (103) are utilized. Thus, among the above three compressors (11a, l ib, 11c), the second largest amount of refrigeration oil can be returned to the second compressor (l ib), so that the three compressors (11a, In l ib, 11c), it is possible to return more refrigeration oil in the order of the first, second and third compressors. As a result, the compressor oil (11a, l ib) can be supplied from the compressor (11a, l ib) with a large amount of refrigeration oil to the compressor (l ib, 11c) with a small amount of refrigeration oil. ), The reliability of each compressor (11a, l ib, 11c) is improved.

[0059] Further, according to the ninth aspect of the invention, the centrifugal force in the main curved portion (101) of the suction main pipe (55) is used to make the out of the three compressors (11a, ib, 11c). Add refrigeration oil to the second compressor (l ib). Since it can be returned to the second most, in the three compressors (11a, l ib, 11c), the refrigeration oil can be returned in the order of the first, second, and third compressors. As a result, the compressor oil (11a, l ib) and the compressor with low refrigerator oil (l ib, 11c) can be supplied to each compressor (11a, l ib). Since the oil can be managed accurately for ib, 11c), the reliability of each compressor (11a, ib, 11c) is improved.

[0060] Further, according to the tenth aspect of the invention, the refrigeration oil stored in the dome of the first compressor (11a) by the oil leveling means (72, 73) is supplied to another compressor (I ib, Since the oil can be supplied to 11c) for proper oil leveling, the shortage of refrigeration oil in each compressor (11a, lib, 11c) can be prevented.

[0061] According to the eleventh aspect of the invention, the oil leveling means (72, 73, 74) causes the refrigerating machine oil stored in the dome of the compressors (11a, LIB, 11c) to be leveled with each other. Since the oil can be mixed with each other and appropriate leveling can be performed, the shortage of refrigeration oil in each compressor (11a, lib, 11c) can be prevented.

[0062] Further, according to the twelfth, twentieth and twenty-first aspects of the invention, the refrigeration oil stored in the dome in the first compressor (11a) is supplied to the second compressor (lib), and the second compressor Refrigeration oil stored in the dome in the compressor (lib) is supplied to the third compressor (11c), and most of the refrigeration oil in the third compressor (11c) is supplied to the first compressor (11a). ). As a result, it is possible to supply the refrigerating machine oil to the compressor (11b, 11c), which has a small amount of refrigerating machine oil (11a, l ib), and perform appropriate oil leveling. Since the excess refrigeration oil in the dome can be circulated between the compressors (11a, l ib, 11c), it is possible to accurately manage the oil for each compressor (11a, l ib, 11c). it can.

[0063] Further, according to the thirteenth aspect of the invention, since the first compressor (11a) is a compressor (11a) having a fixed operating capacity, the first compressor (11a) is being operated. Thus, a large amount of refrigerating machine oil can be reliably returned to the first compressor (11a).

[0064] According to the fourteenth aspect of the invention, since the compressors (11a, ib, 11c) are configured to store refrigeration oil in the high-pressure space in the dome, the compressors (11a, 11b, 11c) l ib, 11c) The effect of improving the reliability by proper oil leveling can be exhibited more remarkably.

[0065] According to the fifteenth aspect of the present invention, the suction branch pipes of the compressors (11a, ib, 11c) Since liquid injection pipes (86, 86a, 86b, 86c) are connected to each of 61a, 61b, 61c), liquid refrigerant can be reliably supplied to each intake branch pipe (61a, 61b, 61c). . As a result, the discharge refrigerant temperature of each compressor (11a, l ib, 11c) can be reliably lowered, and each compressor (1 la, l ib, 11c) can be prevented from becoming too hot. The reliability of each compressor (11a, 1 lb, 11c) can be further improved.

[0066] According to the sixteenth aspect of the invention, since the oil recovery pipe (75, 76, 77) is provided, a predetermined compressor of the plurality of compressors (11a, ib, 11c) is provided. Even when (11a) is stopped, the other compressors (lib, 11c) in operation can suck the refrigeration oil remaining in the suction branch pipe (61a) of the compressor (1 la). As a result, the stopped compressor (11a) does not inhale a large amount of refrigeration oil at the time of restart, so that the compressor (11a) can be prevented from performing liquid compression. The reliability of the compressor (11a) can be further improved.

[0067] In particular, when the first compressor (11a) is stopped most among the plurality of compressors, this reliability improvement effect can be exhibited more remarkably.

[0068] According to the seventeenth aspect of the invention, since the oil recovery pipe (75, 76, 77) is provided, a predetermined compressor of the plurality of compressors (11a, ib, 11c) is provided. Even when (11a) is stopped, the other compressors (lib, 11c) in operation can suck the refrigeration oil remaining in the suction branch pipe (61a) of the compressor (1 la). As a result, the stopped compressor (11a) does not inhale a large amount of refrigeration oil at the time of restart, so that the compressor (11a) can be prevented from performing liquid compression. The reliability of the compressor (11a) can be improved.

[0069] Further, according to the eighteenth and nineteenth inventions, since the oil recovery pipe (75, 76, 77) is connected to the oil reservoir (58) of the suction branch pipe (61a, 61b, 61c). The other compressor (lib, 11c) in operation can reliably suck the refrigeration oil stored in the suction branch pipe (61a) of the stopped compressor (11a).

Brief Description of Drawings

FIG. 1 is a piping system diagram showing a refrigerant circuit of a refrigeration apparatus according to Embodiment 1.

FIG. 2 is a schematic perspective view showing a configuration of a refrigerant pipe on the suction side of the compressor according to the first embodiment.

FIG. 3 shows the direction of refrigerant circulation during the cooling operation of the refrigeration system applied to the first embodiment. FIG.

FIG. 4 is a schematic perspective view showing the configuration of refrigerant piping on the suction side of the compressor according to Embodiment 2.

FIG. 5 is a schematic configuration diagram showing a configuration of refrigerant piping on the suction side of the compressor according to the third embodiment.

Explanation of symbols

1 Refrigeration equipment

10 Refrigerant circuit

11a 1st compressor

l ib 2nd compressor

11c 3rd compressor

55 Inhalation main pipe

56 Suction connection pipe

58 Oil reservoir

59 Slope

61a First suction branch (suction branch)

61b Second suction branch (suction branch)

61c Third suction branch (suction branch)

70 Oil separator

71 Oil return pipe

72 1st oil level pipe

73 Second oil level pipe

74 Third oil leveling pipe

84 Fourth liquid pipe (liquid pipe)

101 Main curve

102 Main branch

103 minor curve

104 Secondary branch no Main drift means

120 Sub-drift means

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Embodiment 1 of the Invention]

As shown in FIG. 1, Embodiment 1 of the present invention is a refrigeration apparatus (1) that performs cooling operation of a cooling chamber, and includes an outdoor unit (2), a refrigeration unit (3), and a controller (100). /!

In the refrigeration apparatus (1), the outdoor unit (2) is provided with an outdoor circuit (20) force, and the refrigeration unit (3) is provided with a refrigerator internal circuit (30). In the refrigeration apparatus (1), the gas end side of the outdoor circuit (20) is connected to the gas end side of the refrigerator internal circuit (30) by a gas side communication pipe (22), and the liquid in the outdoor circuit (20) is connected. The refrigerant circuit (10) of the vapor compression refrigeration cycle is configured by connecting the end side to the liquid end side of the circuit (30) in the refrigerator via the liquid side connecting pipe (21).

[0075] <Outdoor unit>

The outdoor circuit (20) of the outdoor unit (2) includes three compressors (11a, ib, 11c), an outdoor heat exchanger (13), a receiver (14), and a refrigerant heat exchanger. (50), a first expansion valve (45), a second expansion valve (46), and a third expansion valve (47). The outdoor circuit (20) is provided with a four-way switching valve (12), a liquid side closing valve (53), and a gas side closing valve (54). In this outdoor circuit (20), one end of the liquid side connecting pipe (21) is connected to the liquid side closing valve (53), and one end of the gas side connecting pipe (22) is connected to the gas side closing valve (54). Being sung.

[0076] The three compressors (11a, ib, 11c) are connected in parallel to each other in the refrigerant circuit (10). Each of the three compressors (11a, l ib, 11c) is a high-pressure dome type scroll compressor, and the first compressor (11a) and the second compressor (l ib) have an operating capacity. On the other hand, the third compressor (11c) is configured to be fixed, while electric power is supplied via an inverter, and the operating capacity is configured to be variable by changing the output frequency of the inverter. In addition, during operation of the refrigeration system (1), the third compressor (11c) is preferentially driven out of the three compressors (11a, l ib, 11c), and the use side of the refrigeration system (1) Depending on the operating conditions, the second compressor (1 lb) and the first compressor (1 la) are sequentially driven in this order. [0077] The suction main pipe (55) is connected to the suction side of each of the first to third compressors (11a, ib, 11c) via the suction branch pipes (61a, 61b, 61c). Yes. Specifically, the suction main pipe (55) has one end connected to the four-way switching valve (12) and the other end provided with a main branch portion (102). The suction main pipe (55) includes a branch connection between one end of the first suction branch pipe (61a) and one end of the suction connection pipe (56) at the main branch section (102), and the first suction branch pipe (61a) Is connected to the suction side of the first compressor (11a). On the other hand, the suction connection pipe (56) has a sub-branch portion (104) at the other end, and in the sub-branch portion (104), one end of the second suction branch pipe (61b) and the third suction branch pipe (6 One end of lc) is branched. The other end of the second suction branch pipe (61b) is connected to the suction side of the second compressor (lib), while the other end of the third suction branch pipe (61c) is connected to the third compressor. It is connected to the suction side of the compressor (11c). Further, as a feature of the present invention, the main drifting means (110) is provided in the suction main pipe (55), and the subflow drift means (120) is provided in the suction connection pipe (56). This configuration will be described later in more detail with reference to FIG.

[0078] A discharge main pipe (64) is connected to the discharge side of the three compressors (11a, ib, 11c). Specifically, one end of the discharge main pipe (64) is connected to the four-way selector valve (12), while the other end is connected to the first discharge branch pipe (64a), the second discharge branch pipe (64b), and the first discharge branch pipe (64b). Branched to 3 discharge branch pipe (64c). The first discharge branch pipe (64a) is connected to the discharge side of the first compressor (11a), and the second discharge branch pipe (64b) is connected to the discharge side of the second compressor (lib). The third discharge branch pipe (64c) is connected to the discharge side of the third compressor (11c). Each discharge branch pipe (64a, 64b, 64c) has a check valve that allows only the flow of directional refrigerant from the compressors (11a, lib, 11c) to the four-way selector valve (12). CV-1, CV-2, CV-3) Forces are provided respectively.

[0079] The outdoor heat exchanger (13) is a cross-fin type fin 'and' tube heat exchanger, and performs heat exchange between the refrigerant and the outdoor air. The outdoor heat exchanger (13) has one end connected to the four-way selector valve (12) and the other end connected to the top of the receiver (14) via the first liquid pipe (81). The first liquid pipe (81) is provided with a check valve (CV-4) that allows only the refrigerant to flow from the outdoor heat exchanger (13) to the receiver (14). One end of the second liquid pipe (82) is connected to the bottom of the receiver (14).

[0080] The refrigerant heat exchanger (50) is a plate heat exchanger, and exchanges heat between the refrigerant and the refrigerant. The first flow path (50a) and the second flow path (50b) are provided. The first flow path (50a) of the refrigerant heat exchanger (50) has one end connected to the other end of the second liquid pipe (82) and the other end connected to one end of the third liquid pipe (83). ing. The other end of the third liquid pipe (83) is connected to one end of the liquid side connecting pipe (21) via a liquid side closing valve (53). The third liquid pipe (83) is provided with a check valve (CV-5) that allows only the flow of refrigerant from the other end of the first flow path (50a) to the liquid side shut-off valve (53). It has been.

[0081] One end of a fourth liquid pipe (84) is connected to the third liquid pipe (83) on the upstream side of the check valve (CV-5), and the other end of the fourth liquid pipe (84) is connected. The end is connected to one end of the second flow path (50b) of the refrigerant heat exchanger (50). The fourth liquid pipe (84) is provided with a second expansion valve (46). The second expansion valve (46) is an electronic expansion valve whose opening degree is adjustable.

[0082] The other end of the second flow path (50b) of the refrigerant heat exchanger (50) is connected to the suction main pipe (55) via a gas injection pipe (85). The gas injection pipe (85) is for injecting a gas refrigerant into the suction side of the compressor (11a, lib, 11c).

[0083] In the third liquid pipe (83), one end of a fifth liquid pipe (88) is connected between the check valve (CV-5) and the liquid side shut-off valve (53). The other end of the fifth liquid pipe (88) is connected between the check valve (CV-4) and the receiver (14) in the first liquid pipe (81). In addition, the fifth liquid pipe (88) is provided with a check valve (CV-6) that allows only the flow of refrigerant to one end force to the other end.

[0084] Between one end of the fourth liquid pipe (84) and the second expansion valve (46), one end of the sixth liquid pipe (89) is connected, and the sixth liquid pipe (89) The other end is connected between the other end of the outdoor heat exchanger (13) in the first liquid pipe (81) and the check valve (CV-4). The sixth liquid pipe (89) is provided with a first expansion valve (45). The first expansion valve (45) is an electronic expansion valve whose opening degree is adjustable.

[0085] Also, one end of the communication pipe (78) is connected between the check valve (CV-4) and the connection part of the fifth liquid pipe (88) in the first liquid pipe (81). The other end of the communication pipe (78) is connected to the discharge main pipe (64). The communication pipe (78) is provided with a check valve (CV-7) that only allows refrigerant to flow from the receiver (14) to the discharge main pipe (64).

[0086] In the four-way selector valve (12), the first port is the discharge main pipe (64) and the second port is the suction main pipe (5 In 5), the third port is connected to one end of the outdoor heat exchanger (13), and the fourth port is connected to the gas side shut-off valve (54). The four-way selector valve (12) is in the first state (the state indicated by the solid line in FIG. 1) in which the first port and the third port communicate with each other and the second port and the fourth port communicate with each other. ) And the second state (state indicated by the broken line in FIG. 1) in which the first port and the fourth port communicate with each other and the second port and the third port communicate with each other. It is configured.

[0087] Further, the outdoor circuit (20) is provided with an oil separator (70), and as a feature of the present invention, three oil leveling pipes (72, 73, 74) and a liquid injection pipe (86, 86a) are provided. , 86b, 86c) and three oil recovery pipes (75, 76, 77).

[0088] The oil separator (70) is provided in the discharge main pipe (64), and separates the refrigeration oil from the refrigerant discharged from the compressors (11a, ib, 11c). The oil separator (70) is connected to the downstream side of the connection portion of the gas injection pipe (85) in the suction main pipe (55) via the oil return pipe (71). The oil return pipe (71) is provided with a solenoid valve (SV-1). When the solenoid valve (SV-1) is opened, the refrigerating machine oil separated by the oil separator (70) is sucked. It is configured to be returned to the main pipe (55).

[0089] The three oil equalizing pipes (72, 73, 74) are the first oil equalizing pipe (72), the second oil equalizing pipe (73), and the third oil equalizing pipe (74), and constitute oil equalizing means. . The first oil equalizing pipe (72) has one end connected to a predetermined height position of the dome of the first compressor (11a), the other end connected to the suction connecting pipe (56), and a solenoid valve (SV- Has 2). The second oil equalizing pipe (73) has one end connected to a predetermined height position of the dome of the second compressor (lib) and the other end via a third liquid index branch pipe (86c) described later. It is connected to the third suction branch pipe (61c) and has a solenoid valve (SV-3). The third oil equalizing pipe (74) has one end connected to a predetermined height position of the dome of the third compressor (11c) and the other end connected to the oil return pipe (71). (SV-4). The first oil leveling pipe (72) may be connected to the suction main pipe (55), and the second oil leveling pipe (73) may be connected to the second suction branch pipe (61b). 74) can be connected directly to the third inlet branch (61c)! /.

[0090] The liquid injection pipe (86, 86a, 86b, 86c) is composed of a liquid injection main pipe (86) and first to third liquid injection branch pipes (86a, 86b, 86c). . One end of the liquid injection main pipe (86) is connected to one end of the fourth liquid pipe (84) and the sixth liquid pipe (8 9), and the other end is branched and connected to one end of the second liquid injection branch pipe (86b) and one end of the third liquid injection branch pipe (86c). Further, the liquid expansion main pipe (86) is provided with a third expansion valve (47). The third expansion valve (47) is an electronic expansion valve whose opening degree is adjustable. One end of the first liquid injection branch pipe (86a) is connected to the middle of the second liquid injection branch pipe (86b). Each of the first to third liquid injection branch pipes (86a, 86b, 86c) is equipped with a capillary tube (87a, 87b, 87c), and the other end is the first to third compressors (11a). , l ib, 11c) are connected to the intake branch pipes (61a, 61b, 61c). As a result, the liquid refrigerant flowing through the third liquid pipe (83) flows through each liquid indicator branch pipe (86a, 86b, 86c) via the fourth liquid pipe (84) and the liquid injection main pipe (86). , Are supplied to the suction branch pipes (61a, 6 lb, 61c) of the compressors (l la.l lb.l lc).

[0091] The three oil recovery pipes (75, 76, 77) are a first oil recovery pipe (75), a second oil recovery pipe (76), and a third oil recovery pipe (77). One end of the first oil recovery pipe (75) is connected between the connection portion of the first liquid injection branch pipe (86a) and the other end of the first suction branch pipe (61a) of the first compressor (11a). It has been continued. One end of the second oil recovery pipe (76) is connected to the other end of the second liquid branch branch pipe (86b) in the second suction branch pipe (61b) of the second compressor (lib) and the other end. Connected in between. One end of the third oil recovery pipe (77) is connected between the connection portion and the other end of the third liquid instruction branch pipe (86c) in the third suction branch pipe (61c) of the third compressor (11c). It is connected to the. The other ends of the oil recovery pipes (75, 76, 77) are joined together.

The outdoor circuit (20) is provided with various sensors and pressure switches (95a, 95b, 95c, 95d). Specifically, a suction pressure sensor (25) and a suction temperature sensor (24) are provided in the suction main pipe (55), and a discharge pressure sensor (23) is provided in the discharge main pipe (64), and each discharge temperature sensor (19a , 19b, 19c) are provided in each discharge branch pipe (64a, 64b, 64c). A temperature sensor (51) is provided in the third liquid pipe (83) in the vicinity of the connection portion of the first flow path (50a) of the refrigerant heat exchanger (50). In addition, pressure switches (95a, 95b, 95c, 95d) are installed in the piping between the gas side shut-off valve (54) and the four-way selector valve (12) and in each discharge branch pipe (64a, 64b, 64c). It is.

[0093] The outdoor unit (2) includes an outdoor air temperature sensor (13a) and an outdoor fan (13f). It is. Outdoor air is sent to the outdoor heat exchanger (13) by this outdoor fan (13f).

[0094] (Configuration of refrigerant piping on the suction side of the compressor)

Here, the specific configuration of the refrigerant pipes (60a, 60b, 61a, 61b, 61c) on the suction side of the three compressors (11a, ib, 11c), which is a feature of the present invention, is shown in FIG. This will be explained in more detail based on this. In FIG. 2, each compressor (11a, ib) in the third oil leveling pipe (74), each discharge branch pipe (64a, 64b, 64c), and each of the first and second oil leveling pipes (72, 73) is shown. The illustration of the part on the connection side with the dome was omitted.

[0095] As described above, the refrigerant pipe (60a, 60b, 61a, 61b, 61c) on the suction side of the compressor (11a, ib, 11c) has the above-mentioned suction main pipe (55) connected to the main branch ( 102) is branched into a first suction branch pipe (61a) and a suction connection pipe (56), and the suction connection pipe (56) is connected to the second suction branch pipe (61b) and the second suction branch pipe (61b). 3 Branch to the suction branch pipe (61c).

[0096] The suction main pipe (55) extends in the horizontal direction on the downstream side of the connecting portion of the oil return pipe (71), and is provided with a main drifting means (110). The main drifting means (110) includes a main curved portion (101) and the main branch portion (102).

[0097] The main bending portion (101) is an elbow-like pipe connecting pipes connected to the upstream and downstream sides of the main bending section (101) at an angle of 90 °. As a result, in the suction main pipe (55), in FIG. 2, the refrigerant main curved portion (101) that flows from the right back side toward the front side of the suction main pipe (55) is turned leftward. It is configured to flow at a substantially right angle.

The main branch section (102) is a branch joint that branches the refrigerant flow in two directions, and includes a first branch path (102a) and a second branch path (102b). The main branch portion (102) is arranged such that the first branch passage (102a) is located below the second branch passage (102b) and outside the curvature radius direction of the main curved portion (101). Inclined 45 ° downward from the second branch (102b) toward the first branch (102a). The main branch section (102) includes the first suction branch pipe (61a) of the first compressor (11a) in the first branch path (102a) and the suction pipe in the second branch path (102b). Connection pipes (56) are connected to each other. That is, the first suction branch pipe (61a) is located at the lowermost portion of the main branch portion (102) and in the curvature radius direction of the main curved portion (101). Is located at the outermost periphery.

[0099] One end of the first suction branch pipe (61a) is connected to the first branch path (102a) of the main branch section (102), and the other end is connected to the first compressor (11a). ing. Specifically, the first suction branch pipe (61a) is connected to the first branch path (102a) of the main branch section (102) at one end, and is a straight pipe oil sump section (58) extending horizontally. And one end connected to the other end of the oil sump part (58) and inclined upward toward the downstream side, and the first part extending vertically downward from the top of the inclined part (59). And a vertical section (60) connected to the compressor (11a). The oil reservoir (58) of the first suction branch pipe (61a) has, in order from the upstream side, the first liquid injection branch pipe (86a) at the top and the first oil recovery pipe (75) at the bottom. Are connected to each other.

[0100] The suction connection pipe (56) extends in the horizontal direction and includes sub-diffusion means (120). The sub-diffusion means (120) includes a sub-bending portion (103) and the sub-branching portion (104). In addition, a first oil equalizing pipe (72) is connected to the suction connecting pipe (56) on the downstream side of the sub-curved portion (103).

[0101] The sub-curved portion (103) is composed of an elbow-shaped pipe connecting pipes connected to the upstream and downstream sides of the sub-curved portion (103) at an angle of 90 °. As a result, in the suction connection pipe (56), in FIG. 2, the refrigerant that has flowed with the one end force of the suction connection pipe (56) directed to the left side is substantially rearward in the sub-curved portion (103). It is configured to flow at a right angle.

[0102] The sub-branch portion (104) is a branch joint that branches the refrigerant flow in two directions, and includes a first branch passage (104a) and a second branch passage (104b). The sub-branch portion (104) is arranged such that the first branch passage (104a) is located below the second branch passage (104b) and outside the curvature radius direction of the sub-curvature portion (103). Inclined 45 ° downward from the second branch (104b) toward the first branch (104a). The sub-branch section (104) includes the second branch pipe (61b) of the second compressor (1 lb) in the first branch path (104a) and the second branch path (104b). The third suction branch pipe (61c) of the third compressor (1 lc) is connected to each other.

[0103] One end of the second suction branch pipe (61b) is connected to the first branch path (104a) of the sub-branch portion (104), while the other end is suctioned by the second compressor (lib). Connected to the side. Specifically, one end of the second suction branch pipe (61b) is in contact with the first branch path (104a) of the sub branch section (104). A straight oil sump portion (58) that extends horizontally and is connected to the other end of the oil sump portion (58), and an inclined portion (59) that is inclined upward toward the downstream side, A vertical portion (60) that extends vertically downward from the top of the inclined portion (59) and is connected to the second compressor (12a) is provided in order. In addition, the first liquid injection branch pipe (86a) is connected to the oil reservoir (58) of the second suction branch pipe (61b) at the top, and the first oil recovery pipe (75) is connected to the bottom. ing.

[0104] The third suction branch pipe (61c) has one end connected to the second branch path (104b) of the sub-branch section (104) and the other end connected to the suction side of the third compressor (11c). It is connected to the. The third suction branch pipe (61c) does not have an oil sump part (58) and an inclined part (59), extends horizontally from one end to the other end, bends downward, and extends vertically downward. It extends. In addition, the third liquid injection branch pipe (86c) and the second oil equalizing pipe (73) are joined to the upper part of the horizontal portion of the third suction branch pipe (61c) and connected to the lower part on the downstream side. A third oil recovery pipe (77) is connected to the pipe.

[0105] The other end of each of the first to third oil recovery pipes (75, 76, 77) is connected to the connection portion of the second oil recovery pipe (75) in the second suction branch pipe (61b). In the vertically downward direction, they are joined together.

[0106] <Refrigerated unit>

As shown in Fig. 1, in the refrigerator internal circuit (30) of the refrigeration unit (3), the refrigeration heat exchanger (16, 17), the drain pan heater (26, 27), the refrigeration expansion valve (15a, 15b) There will be 2 each!

[0107] Each of the above refrigerated heat exchanges ^^ (16, 17) is the same cross fin type fin 'and' tube type heat exchange ^^, and heat exchange is performed between the refrigerant and the air in the cooling chamber. Is to do. One end of each refrigeration heat exchanger (16, 17) is connected to one end of each drain pan heater (16, 17) via each refrigeration expansion valve (15a, 15b), and the other end is connected to each gas side branch pipe. It is connected to one end of (22a, 22b). The gas side branch pipes (22a, 22b) are joined to each other at the other end and connected to the other end of the gas side connecting pipe (22).

[0108] Each of the refrigeration expansion valves (15a, 15b) is an electronic expansion valve whose opening degree can be adjusted. Each of the refrigeration heat exchangers (16, 17) is provided with a first refrigerant temperature sensor (16b, 17b) for measuring the evaporation temperature of the refrigerant, while each of the refrigeration heat exchangers (16, 17). The other end Two refrigerant temperature sensors (18a, 18b) are provided, respectively. The refrigeration expansion valve (15a, 15b) has a temperature measured by the second refrigerant temperature sensor (18a, 18b) that is a predetermined temperature (for example, higher than the refrigerant evaporation temperature measured by the first refrigerant temperature sensor (16b, 17b)). (5 ° C) The opening is adjusted to be higher.

[0109] The drain pan heaters (26, 27) are arranged in a drain pan of a refrigeration heat exchanger (16, 17) (not shown), and a high-temperature and high-pressure refrigerant flows to heat the drain pan, thereby It prevents generation. The other end of each drain pan heater (26, 27) is connected to one end of each liquid side branch pipe (21a, 21b), and the other end of each liquid side branch pipe (21a, 21b) joins each other. Connected to the other end of the liquid side connecting pipe (21).

[0110] Further, the refrigeration unit (3) is provided with cooling room temperature sensors (16a, 17a) and cooling room fans (16f, 17f). Air in the cooling chamber is sent to the refrigeration heat exchangers (16, 17) by the fans (16f, 17f) in the cooling chamber.

[0111] <Controller>

The controller (100) includes various valves (SV-1, SV-2, SV-3, SV-4, 12, 46, 47, 48, 15a, 15b) provided in the refrigerant circuit (10). In addition to switching and opening adjustment, the compressor (11a, ib, 11c) and fan (13f, 16f, 17f) are driven to control the operation of the refrigeration system (1).

[0112] Driving action

Next, the operation of the refrigeration apparatus (1) of this embodiment will be described.

[0113] The refrigeration apparatus (1) is configured to perform a defrosting operation by temporarily stopping the cooling operation while performing a cooling operation in the cooling chamber, for example, at a set temperature of 5 ° C. ing.

[0114] <Cooling operation>

In the cooling operation, as shown in FIG. 3, the four-way selector valve (12) of the outdoor circuit (20) is set to the first state and the first expansion valve (45) is fully closed under the control of the controller (100). Is done. In this state, the first to third compressors (11a, ib, 11c) are driven, and the refrigeration expansion valves (15a, 15b), the second expansion valve (46), and the third expansion valve are driven. (47) is appropriately adjusted to open, and the refrigerant circulates in the direction of the solid arrow in FIG. 3, while the outdoor fan (13f) and the refrigeration fans (16f, 17f) are driven. In addition, the controller (100) allows the solenoid valve (SV-1) of the oil return pipe (71) to be The solenoid valve of each oil leveling pipe (72, 73, 74) is, for example, the solenoid valve (SV-2) of the first oil leveling pipe (72) and the solenoid valve of the second oil leveling pipe (73) ( SV-3) and solenoid valve (SV-4) of third oil leveling pipe (74) are controlled to open in this order.

[0115] Refrigerant that has also discharged the first to third compressors (11a, l ib, 11c) force flows from each discharge branch pipe (64a, 64b, 64c) to the discharge main pipe (64), and is a four-way switching valve. It is sent to the outdoor heat exchanger (13) through (12). In the outdoor heat exchanger (13), the refrigerant dissipates heat to the outdoor air and is condensed and liquefied. The liquefied refrigerant flows through the first liquid pipe (81), passes through the receiver (14), flows into the second liquid pipe (82), and enters the first flow path (50a) of the refrigerant heat exchanger (50). Flow into. The liquid coolant that has flowed through the first flow path (50a) flows through the third liquid pipe (83), part of which is shown in the fourth liquid pipe (a, b) as shown by the dashed arrows (a, b) in FIG. 84).

[0116] A portion of the refrigerant flowing into the fourth liquid pipe (84) is depressurized through the second expansion valve (46) as indicated by the broken line arrow (a), and the refrigerant heat exchanger (50) Heat is exchanged with the liquid refrigerant flowing into the second flow path (50b) and flowing through the first flow path (50a) to evaporate, and the liquid refrigerant flowing through the first flow path (50a) is cooled to a predetermined low temperature. . Then, the liquid refrigerant flowing through the first flow path (50a) exchanges heat with the branched refrigerant flowing through the second flow path (50b), and is cooled to, for example, 15 ° C., and then the third liquid pipe (83) And flows through the liquid side connecting pipe (21) via the liquid side closing valve (53) and flows into the refrigerator internal circuit (30). Further, the branched liquid refrigerant in the second flow path (50b) evaporates and is injected into the suction main pipe (55) through the gas injection pipe (85).

[0117] Further, the remaining part of the refrigerant that has flowed through the fourth liquid pipe (84) flows through the liquid injection main pipe (86) as shown by the dashed arrow (b), and the third expansion whose opening degree is adjusted is shown. Flow through valve (47), divert to each liquid junction branch pipe (86a, 86b, 86c), and supply to suction branch pipe (61a, 61b, 61c) of each compressor (11a, lib, 11c) Is done.

[0118] In the refrigerator internal circuit (30), the liquid refrigerant power at 15 ° C is diverted to the liquid side branch pipes (21a, 21b) and flows through the drain pan heaters (26, 27) to prevent the drain pan from frosting. At the same time, the refrigerated heat exchanger (16, 17) will surely melt the frost that has fallen into the drain pan. Drain pan heater (26, 27) force The liquid refrigerant that has flowed out is decompressed and expanded when passing through each refrigeration expansion valve (15a, 15b), and is introduced into each refrigeration heat exchanger m ^ (16, 17). In each refrigeration heat exchanger (16, 17), the refrigerant absorbs heat from the air in the cooling chamber and evaporates at an evaporation temperature of, for example, about 5 ° C. This As a result, in the refrigeration unit (3), the air cooled by the refrigeration heat exchanger (16, 17) is supplied into the cooling chamber, and the temperature in the cooling chamber is maintained at the set temperature of 5 ° C.

[0119] The gas refrigerant evaporated in each of the refrigeration heat exchanges (16, 17) flows through the gas side branch pipes (22a, 22b) and then merges in the gas side communication pipe (22). Thereafter, the gas refrigerant flows through the gas side communication pipe (22), and then flows through the suction main pipe (55) via the four-way switching valve (12). The refrigerant flowing through the suction main pipe (55) is divided into the first suction branch pipe (61a) and the suction connection pipe (56), and the refrigerant flowing through the first suction branch pipe (61a) is first compressed. It is sucked into the machine (11a) and compressed. On the other hand, the refrigerant flowing through the suction connection pipe (56) is divided into the second suction branch pipe (61b) and the third suction branch pipe (61c), and the refrigerant flowing through the second suction branch pipe (61b) The refrigerant that has been sucked into the second compressor (lib) and compressed and has flowed through the third suction branch pipe (61c) is sucked into the third compressor (11c) and compressed.

[0120] (Refrigerating machine oil return operation)

Here, during the cooling operation, when all of the three compressors (11a, l ib, 11c) are driven, the refrigerating machine oil in the suction main pipe (55) becomes the first, second, second Go back in order of 3 compressors. In addition, between the compressors (11a, l ib, 11c), compressors (11a, l ib) with a small amount of refrigerating machine oil return by means of oil equalizing pipes (72, 73, 74) (l Refrigerating machine oil is supplied to ib, 11c) in order, and oil leveling is performed.

[0121] Specifically, as shown in Fig. 2, in the suction main pipe (55), the refrigeration oil separated from the discharged refrigerant by the oil separator (70) is supplied by the oil return pipe (71), and the oil return Downstream of the pipe (71), the refrigerant and the refrigerating machine oil are mixed and flow. The refrigerant and the refrigerating machine oil are located on the downstream side of the main bending portion (101) due to the gravity acting when flowing through the suction main pipe (55) and the centrifugal force acting when flowing through the main bending portion (101). On the other hand, the refrigeration oil flows downward and outward with respect to the radius of curvature of the main curved portion (101). Then, the first suction branch pipe (61a) of the first compressor (11a) is the lowermost part of the main branch part (102) and the outermost peripheral part of the main curved part (101) in the radius direction of curvature. Therefore, most of the refrigeration oil in the suction main pipe (55) flows into the first suction branch pipe (61a). Also, since the operating capacity of the first compressor (11a) is fixed, the refrigerating machine oil that has flowed into the first intake branch pipe (61a) is reliably sucked into the first compressor (11a). Saving Be retained.

[0122] The refrigerant flowing into the suction connection pipe (56) contains a small amount of refrigerating machine oil. The refrigerant and the refrigerating machine oil are provided on the downstream side of the sub-curved portion (103) due to gravity acting when flowing through the suction connecting pipe (56) and centrifugal force acting when flowing through the sub-curved portion (103). Refrigerant flows upward and inward with respect to the radius of curvature of the sub-curved portion (103), while refrigeration oil flows downward and outward of the radius of curvature of the sub-curved portion (103). In the sub-branch section (104), the second suction branch pipe (61b) of the second compressor (l ib) is connected to the third suction branch pipe (61c) of the third compressor (1 lc). Since it is located further downward and outside the curvature radius direction of the auxiliary curved portion (103), a large amount of refrigerating machine oil flowing through the suction connection pipe (56) flows into the second suction branch pipe (61b). To do. In addition, since the operating capacity of the second compressor (l ib) is fixed, the refrigerating machine oil that has flowed into the second intake branch pipe (61b) is reliably sucked into the second compressor (l ib). ib).

[0123] The remaining refrigeration oil flows together with the refrigerant into the third suction branch pipe (61c) of the third compressor (11c), and is sucked into the third compressor (11c). In this way, the refrigerating machine oil returns in the order of the first, second and third compressors.

[0124] Then, the liquid refrigerant is individually injected into each intake branch pipe (61a, 61b, 61c) by each of the liquid instruction branch pipes (86a, 86b, 86c). Here, if the liquid refrigerant is indicated in the suction main pipe (55) or the suction connection pipe (56), the liquid refrigerant will be dissolved in the refrigeration oil, so that the liquid refrigerant is in the first, second, and third compressors. The amount of refrigerant is supplied in order, but since the injection branch pipes (61a, 61b, 61c) are individually injected, the discharge refrigerant temperature of each compressor (11 a, ib, 11c) is reliably reduced. In addition, the compressors (11a, l ib, 11c) themselves can be prevented from becoming too hot.

On the other hand, as described above, under the control of the controller (100), the solenoid valves of the oil level equalizing pipes (72, 73, 74) are, for example, the solenoid valves (SV-2) of the first oil level equalizing pipe (72). ), Solenoid valve (SV-3) of the second oil equalizing pipe (73), and solenoid valve (SV-4) of the third oil equalizing pipe (74) are opened in this order.

[0126] That is, first, the solenoid valve (SV-2) of the first oil leveling pipe (72) is opened, and the refrigeration oil in the dome of the first compressor (11a) is moved to the first oil leveling pipe ( 72) through the suction connection pipe (56). The refrigerating machine oil supplied to the suction connection pipe (56) is the weight of the refrigerant and the refrigerating machine oil. Due to the difference, it flows through the lower part of the suction connection pipe (56) and flows to the second suction branch pipe (61b). In other words, the first oil leveling pipe (72) also supplies the first compressor (11a) power to the second compressor (l ib) and ensures that the second compressor (l ib) is also supplied with the refrigeration oil. Store.

[0127] If the first oil equalizing pipe (72) may be connected to the upstream side of the sub-curved portion (103) in the suction connecting pipe (56), the first oil equalizing pipe (72) may be used. A large amount of the refrigeration oil supplied to the suction connection pipe (56) flows to the second suction branch pipe (61b) due to gravity and the centrifugal force in the sub-curved portion (103). Connect the first oil leveling pipe (72) to the second suction branch pipe (61b) instead of the suction connection pipe (56).

[0128] Next, the solenoid valve (SV-3) of the second oil equalizing pipe (73) is opened with a large amount of refrigeration oil stored in the dome of the second compressor (lib). Then, the refrigeration oil in the dome of the second compressor (lib) is supplied to the third suction branch pipe (61c) via the second oil equalizing pipe (73), and the refrigeration oil is supplied to the third compressor (11c ). In this way, the refrigeration oil is reliably stored in the third compressor (11c).

[0129] As described above, the solenoid valve (SV-4) of the third oil leveling pipe (74) is in an open state in a state where a large amount of refrigeration oil is stored in the dome of the third compressor (11c). Become. As a result, surplus refrigeration oil in the third compressor (11c) is supplied to the oil return pipe (71) via the third oil equalizing pipe (74), and the first compression pipe (55) is configured to perform the first compression. A lot is returned to the machine (11a).

[0130] Here, the first compressor (11a) may stop depending on the operating condition (cooling load) on the user side. In that case, the refrigeration oil stays in the oil reservoir (58) of the suction branch pipe (61a) of the first compressor (11a) and the liquid refrigerant injected by the liquid injection pipe (86, 86a) stays there. . Since the second and third compressors (lib, 11c) are in operation, the refrigerating machine oil and the liquid refrigerant accumulated in the oil reservoir (58) of the first intake branch pipe (61a) It is introduced into the suction branch pipes (61b, 61c) of the second and third compressors (l ib, 11c) through the collecting pipes (75, 76, 77), and the second and third compressors (l ib, Inhaled in 11c). As a result, the stopped first compressor (11a) does not suck a large amount of refrigeration oil when it is restarted. Therefore, the compressor (11a) may perform liquid compression simultaneously with the restart. There is no.

[0131] When the second compressor (lib) is stopped in addition to the first compressor (11a), the oil sump (58) of the first and second suction pipes (61a, 61b) ) Refrigerating machine oil and liquid refrigerant accumulated in It is sucked into the third compressor (ie) inside through the oil recovery pipe (75, 76, 77).

[0132] <Defrosting operation>

In the defrosting operation, although not shown, the four-way selector valve (12) is set to the second state, the refrigeration expansion valves (15a, 15b) are fully open, the second expansion valve (46) is fully closed, The opening degree of the first and second expansion valves (4 5, 46) is appropriately adjusted, and reverse cycle defrost is performed in which the refrigerant circulates in the reverse direction to that during the cooling operation.

[0133] Specifically, the refrigerant discharged from the three compressors (11a, ib, 11c) flows through the refrigeration heat exchangers (16, 17) and the drain pan heaters (26, 27). Refrigeration heat exchange ^^ (16, 17) and frost adhering to the drain pan dissipate heat to condense. The liquefied refrigerant flows through the liquid side connecting pipe (21), is introduced into the outdoor circuit (20), flows through the fifth liquid pipe (88), and the receiver (14) and the refrigerant heat exchanger (50). Through the first flow path (50a). Then, when the refrigerant flows through the sixth liquid pipe (89), the refrigerant expands in the first expansion valve (45), condenses in the outdoor heat exchanger (13), and passes through the four-way switching valve (12) to the suction main pipe. Flows through (55), branches into the suction branch pipes (61a, 61b, 61c), and is sucked into the compressors (11a, 11b, 11c).

[0134] During this defrosting operation, as in the above cooling operation, the amount of refrigeration oil returns in the order of the first, second, and third compressors, and each compressor (11a, lib, 11c ), The refrigerating machine oil is sequentially supplied to the compressor (11b, 11b) with a small return by the oil leveling pipe (72, 73, 74). Smooth oil leveling is performed.

[0135] Effect of Embodiment 1

In the refrigeration system (1), the first compressor (11a) is supplied with the largest amount of refrigerating machine oil by utilizing the difference in gravity and centrifugal force between the refrigerant and the refrigerating machine oil flowing through the suction main pipe (55). Since it can be returned, the refrigerating machine oil can be reliably stored in the dome of the first compressor (11a). Further, the second compressor (l ib) is connected to the third compressor (11c) by utilizing the difference in gravity and centrifugal force between the refrigerant and the refrigerating machine oil flowing through the suction connection pipe (56). More refrigeration oil can be returned. Thus, the amount of refrigeration oil can be returned in the order of the first, second, and third compressors.

[0136] In addition, the first oil leveling pipe (72) supplies the refrigeration oil stored in the dome in the first compressor (11a) with the largest amount of refrigeration oil to the second compressor (lib) and supplies the second compression oil. Refrigerating machine oil can be reliably stored in the machine (l ib). Then, the cold stored in the dome in the second compressor (lib) By supplying the refrigeration oil to the third compressor (11c) through the second oil equalizing pipe (73), the refrigeration oil can be reliably stored in the third compressor (11c). Furthermore, the third oil leveling pipe (74) can return the surplus refrigeration oil in the third compressor (11c) to the first compressor (11a). In this way, the compressor oil (11a, ib, 11c) is supplied to the compressor (11b, 11c) with a small amount of return of the refrigeration oil and supplied to the compressor (11b, 11c) with little power. It is possible to perform appropriate oil leveling by circulating excess frozen oil in the dome.

[0137] If only the first compressor (11a) or the first and second compressors (11a, ib) are stopped, the other compressors (lib, 11c) in operation are stopped. Refrigerator oil and liquid refrigerant accumulated in the oil sump (58) of the suction branch pipe (6 la, 61b) of the compressor (11a, li ib) of the compressor through the oil recovery pipe (75, 76, 7) Since the compressor (11a) can be sucked in, the compressor (11a) in the stopped state does not suck in a large amount of refrigeration oil and refrigerant in the liquid state at the time of restart. Can be prevented. In particular, in this embodiment, a large amount of refrigerating machine oil returns to the suction branch pipes (61a, 61b, 61c) in the order of the first, second, and third compressors, while the first and second compressors decrease when the cooling load during operation decreases. Since the second and third compressors are stopped in this order, the effect of the oil recovery pipe (75, 76, 77) can be exhibited more remarkably.

[0138] As described above, the refrigeration apparatus (1) can prevent the shortage of refrigeration oil in each compressor (11a, ib, 11c), and the refrigeration apparatus (1) is in operation. Even if the first and second compressors (11a, l ib) are stopped, liquid compression can be prevented when restarted. In other words, the refrigeration system (1) can accurately manage the oil for each compressor (11a, l ib, 11c), improving the reliability of each compressor (11a, l ib, 11c). To do.

<< Embodiment 2 of the Invention >>

In the present embodiment, the main drifting means (110) of the first embodiment is composed of a main bending part (101) and a main branching part (102), and the sub drifting means (120) is constituted by a sub bending part (103) and a sub bending part (103). As shown in FIG. 4, the main drifting means (110) is composed of only the main branching part (102), and the sub-drifting means (120) is arranged as the sub-branching part. (104) Only force is composed. That is, in the present embodiment, the centrifugal force in the curved portions (101, 103) does not act on the refrigerant and the refrigerating machine oil flowing through the pipe (55, 56) on the suction side, and the first, second, The amount of refrigeration oil is returned in the order of the third compressor. In Fig. 4, the liquid The illustration of the branch pipe (86a, 86b, 86c) is omitted.

[0140] Specifically, as shown in Fig. 4, the suction main pipe (55) extends in the horizontal direction on the downstream side of the connecting portion of the oil return pipe (71), while at the end on the most downstream side. The other end is provided with a main branching portion (102) as main drifting means (110).

[0141] The main branch section (102) includes a first branch path (102a) and a second branch path (102b), and the second branch path (102b) is directed toward the first branch path (102a). ° Inclined downward. The first suction branch pipe (61a) of the first compressor (11a) is connected to the first branch path (102a), and the suction connection pipe (56) is connected to the second branch path (102b). It is connected. That is, the first suction branch pipe (61a) is located at the lowermost portion of the main branch section (102).

[0142] The first suction branch pipe (61a) has one end connected to the first branch (102a) of the main branch (102) and the other end connected to the suction side of the first compressor (11a). It is connected to the. Specifically, the first suction branch pipe (61a) has one end connected to the first branch path (102a) of the main branch section (102) and separated from the suction connection pipe (56). A downwardly inclined part (63) inclined downward, an oil reservoir part (58) of a straight pipe that extends horizontally with one end connected to the other end of the descender part (63), and one end of the other end of the oil reservoir part (58) An inclined portion (59) which is inclined upward by being directed to the downstream side, and a vertical portion (60) extending vertically downward from the top of the inclined portion (59) and connected to the first compressor (11a) In order. In the first suction branch pipe (61a), one end of the first oil recovery pipe (75) is connected to the lower part of the most downstream end of the oil reservoir (58).

[0143] One end of the suction connection pipe (56) is connected to the second branch path (102b) of the main branch section (102), and the other end is a sub branch section (104) serving as a sub-diffusion means (120). ). The suction connecting pipe (56) extends in the horizontal direction from one end to the other end, and the first oil equalizing pipe (72) is connected to the middle.

[0144] The sub-branch section (104) includes a first branch path (104a) and a second branch path (104b), and is directed from the second branch path (104b) to the first branch path (104a). Inclined 45 ° downward. One end of the second suction branch pipe (61b) of the second compressor (1 lb) is connected to the first branch path (104a), and the third branch path (104b) is connected to the third branch path (104b). Is connected to the third suction branch pipe (61c) of the compressor (11c).

[0145] One end of the second suction branch pipe (61b) is the first branch path (104a) of the sub branch section (104). The other end is connected to the suction side of the second compressor (I ib). Specifically, the second suction branch pipe (61b) is connected to the first branch passage (104a) of the sub-branch part (104) at one end and a straight oil sump part (58) extending horizontally. One end is connected to the other end of the oil reservoir (58), and the inclined portion (59) that is inclined upward by directing toward the downstream side, and one end is connected to the top of the inclined portion (59) and horizontally A horizontal part (62) that extends, and a vertical part (60) that has one end connected to the other end of the horizontal part (62), extends vertically downward, and is connected to the second compressor (12a) are provided in order. Speak. In the second suction branch pipe (61b), one end of the second oil recovery pipe (76) is connected to the lower part of the most downstream end of the oil reservoir (58).

[0146] One end of the third suction branch pipe (61c) is connected to the second branch path (104b) of the sub-branch section (104), and the other end is the suction side of the third compressor (11c). It is connected to the. The third suction branch pipe (61c) does not have an oil reservoir part (58) and an inclined part (59), extends from one end to the other end, extends in the horizontal direction, bends downward, and extends vertically downward. ing. In addition, a second oil equalizing pipe (73) is connected to the upper part of the horizontal portion of the third suction branch pipe (61c), and one end of the third oil recovery pipe (77) is connected to the lower part of the downstream side. It has been.

In the present embodiment, in the suction main pipe (55), the refrigerant flows upward while the refrigerator oil flows downward due to the difference in gravity between the refrigerant and the refrigerator oil. In the main branch section (102), since the suction branch pipe (61a) of the first compressor (11a) is located at the lowermost part, the refrigeration that has flowed under the suction main pipe (55) Most of the machine oil flows into the intake branch pipe (6 la) of the first compressor (11a).

[0148] The refrigerant flowing into the suction connection pipe (56) also contains a small amount of refrigeration oil. The refrigerant and the refrigeration oil flowing through the suction connection pipe (56) are caused by the difference in gravity between the refrigerant and the refrigeration oil. The refrigerant flows upward, while the refrigeration oil flows downward. In the sub-branch portion (104), the second suction branch pipe (61b) of the second compressor (l ib) is located below the third suction branch pipe (61c) of the third compressor (11c). Therefore, most of the refrigeration oil flowing through the suction connection pipe (56) flows into the second suction branch pipe (61b).

[0149] In addition, the remaining refrigeration oil flows together with the refrigerant through the third suction branch pipe (61c) of the third compressor (11c), and is sucked into the third compressor (11c). In this way, the refrigerating machine oil returns in the order of the first, second and third compressors. [0150] Then, the refrigeration oil in the dome of the first compressor (11a) is supplied to the suction connection pipe (56) by the first oil equalizing pipe (72). Due to the difference in weight with the machine oil, it flows downward in the suction connection pipe (56) and flows to the second suction branch pipe (61b). In other words, the first oil leveling pipe (72) also supplies the first compressor (11a) force to the second compressor (l ib) and ensures that the second compressor (l ib) is also supplied with the refrigeration oil. Store.

[0151] The second oil leveling pipe (73) supplies the refrigeration oil in the dome of the second compressor (lib) to the third suction branch pipe (61c), and the refrigeration oil is supplied to the third compressor (11c). ) Is inhaled. In this way, the refrigeration oil is supplied from the second compressor (lib) to the third compressor (11c), and the refrigeration oil is reliably stored in the third compressor (11c). The surplus refrigeration oil of the third compressor (11c) is supplied to the oil return pipe (71) via the third oil equalizing pipe (not shown), and the first compression is made by the configuration of the suction main pipe (55). A lot is returned to the machine (11a). In this way, appropriate oil leveling can be performed between the compressors (11a, l ib, 11c).

[0152] If only the first compressor (11a) or the first and second compressors (11a, ib) are stopped, the other compressors (lib, 11c) in operation are stopped. Refrigerating machine oil staying in the oil reservoir (58) of the suction branch pipe (61a, 61b) of the compressor (11a, ib) can be sucked through the oil recovery pipe (75, 76, 77). . This can prevent the stopped compressor (11a, ib) from sucking a large amount of refrigeration oil in the liquid state and performing liquid compression during restart.

[0153] Other configurations, operations, and effects are the same as those in the first embodiment.

<< Embodiment 3 of the Invention >>

In this embodiment, the sub-diffusion means (120) of the first embodiment is composed of the sub-curvature portion (103) and the sub-branch portion (104) of the suction connection pipe (56). As shown, the sub-diffusion means (120) is composed of a main curved portion (101) of the suction main pipe (55) and a sub-branch portion (104) of the suction connection pipe (56). That is, in the present embodiment, the centrifugal force in the main curved portion (101) of the suction main pipe (55) is used to drift the refrigerating machine oil flowing through the suction connection pipe (56). In FIG. 5, the liquid injection branch pipes (86a, 86b, 86c) are not shown.

[0155] Specifically, as shown in Fig. 5, the suction main pipe (55) is arranged on the downstream side of the connecting portion of the oil return pipe (71), and the main curved portion (101) constituting the main drifting means (110). And main branch (102)! Further, the piping configuration downstream of the main branching portion (102) is the same as the piping configuration shown in FIG.

Thus, in the refrigeration apparatus (1), in the suction main pipe (55), due to the gravity difference between the refrigerant and the refrigeration machine oil and the centrifugal force difference acting on the main curved portion (101), the refrigerant is upward and While the main curved portion (101) flows inward with respect to the radius of curvature, the refrigerating machine oil flows downward and outward with respect to the radius of curvature of the main curved portion (101). In the main branch portion (102), the suction branch pipe (61a) of the first compressor (11a) is the outermost peripheral portion at the lowermost portion and in the curvature radius direction of the main curved portion (101). As a result, most of the refrigeration oil flowing through the suction main pipe (55) flows into the suction branch pipe (61a) of the first compressor (11a).

[0157] The refrigerant flowing into the suction connection pipe (56) also contains a small amount of refrigerating machine oil. In the suction connection pipe (56), the refrigerant and the refrigerating machine oil are separated from each other by the gravity difference and the centrifugal force difference in the main curved portion (101) of the suction main pipe (55). ) Flows inside in the direction of the radius of curvature, while refrigeration oil flows down and outside of the radius of curvature of the main curved portion (101). In the sub-branch section (104), the suction branch pipe (61b) of the second compressor (1 lb) is connected to the suction main pipe (61c) rather than the suction branch pipe (61c) of the third compressor (1 lc). 55) is located outside the radius of curvature of the main curved portion (101), so that the refrigerating machine oil in the suction connection pipe (56) is fed into the suction branch pipe of the third compressor (11c). It flows more into the suction branch pipe (61c) of the second compressor (l ib) than (61c).

[0158] Then, the remaining refrigeration oil flows together with the refrigerant into the third suction branch pipe (61c) of the third compressor (11c). In this way, the refrigerating machine oil returns in the order of the intake branch pipes (61a, 61b, 61c) of the first, second and third compressors.

[0159] Other configurations, operations, and effects are the same as those in the first embodiment.

[0160] << Other Embodiments >>

For the above embodiment, the following configuration may be used.

[0161] In the first and third embodiments, the first branch (102a, 104a) is located below the second branch (102b, 104b) in the main branch (102) and the sub branch (104). The first branch (102a, 104a) and the second branch (102b, 104b) may be arranged horizontally. . Even in this case, the first branch path (102a) of the main branch section (102) is located outside the second branch path (102b) with respect to the radius of curvature of the main curved section (101), and the sub-branch Since the first branch path (104a) of the section (104) is outward from the second branch path (104b) with respect to the radius of curvature of the sub-curved section (103) and the main curved section (101), the curved section Only by the action of the centrifugal force at (101, 103), the refrigerating machine oil may return more in the order of the first, second, and third compressors.

[0162] Further, the refrigeration apparatus (1) of each of the above embodiments is configured to include three compressors. The number of power units is not limited to three. For example, a configuration in which two compressors are connected in parallel and a large amount of oil is returned to one compressor may be employed.

[0163] Further, the drifting means (110, 120) is not limited to the configuration shown in each of the above embodiments, and the configuration in which the suction main pipe (55) force also branches to the suction branch pipes (61a, 61b, 61c). There is no particular limitation. For example, from the upstream side to the downstream side of the suction main pipe (55), the suction branch pipe (61c) of the third compressor (11c) first branches, and then the first compressor (11a) and the second compressor ( In this configuration, the suction branch pipe (61a) of the first compressor (11a) may be connected to the suction main pipe (55), which may be branched to the suction branch pipe (61a, 61b). It is possible to adopt a configuration in which most of the refrigeration oil flows. Furthermore, in this configuration, the refrigerating machine oil may return in the order of the first, second, and third compressors.

[0164] In addition, the refrigeration apparatus (1) of Embodiment 1 described above includes the refrigerant circuit (10) of the vapor compression refrigeration site that compresses the refrigerant in one stage, but the refrigeration apparatus (1) uses the refrigerant. A refrigerant circuit for two-stage compression may be provided. In that case, a low-stage compression mechanism and a high-stage compression mechanism that perform two-stage compression are configured by connecting a plurality of compressors (for example, first to third compressors) in parallel, and each compression In the mechanism, the refrigerating machine oil may return in the order of the first, second, and third compressors. In each compression mechanism, the refrigeration oil may be supplied through an oil equalizing pipe from a compressor having a large amount of refrigeration oil to a small V-type compressor! In the compression mechanism on the lower stage side, the most refrigeration oil is supplied. A configuration may be adopted in which the refrigeration oil in the dome of the third compressor with a small return amount is supplied to the suction side of the higher-stage compression mechanism via an oil equalizing pipe.

[0165] The above embodiments are essentially preferable examples, and are not intended to limit the scope of the present invention, its application, or its use.

Industrial applicability As described above, the present invention is useful for a refrigeration apparatus including a plurality of compressors connected in parallel.

Claims

The scope of the claims

[1] A plurality of compressors (11a, l ib, 11c) connected in parallel to each other, and an oil separator (70) for separating refrigeration oil from refrigerant discharged from the compressors (11a, l ib, 11c) A refrigerant circuit (10) having

The refrigerant pipe of the refrigerant circuit (10) includes a suction main pipe (55) through which the suction refrigerant of the compressor (11a, ib, 11c) flows, and the refrigerant in the suction main pipe (55) is sent to each compressor (11a, ib). , 11c) and an intake branch pipe (61a, 61b, 61c) and an oil return pipe (71) for returning the refrigeration oil separated by the oil separator (70) to the suction main pipe (55). A refrigeration device,

The suction main pipe (55) is arranged so that a large amount of refrigerating machine oil flows into the suction branch pipe (61a) of the first compressor (11a) set in advance among the compressors (11a, ib, 11c). A main drifting means (110) for drifting the refrigeration machine oil in the suction main pipe (55) is provided on the downstream side of the connection part of the oil return pipe (71).

A refrigeration apparatus characterized by that.

[2] A plurality of compressors (11a, l ib, 11c) connected in parallel to each other, and the compressors (11a, l ib,

A refrigerant circuit (10) having an oil separator (70) for separating refrigeration oil from the discharged refrigerant of 11c),

The suction main pipe (55) includes a main bending portion (101) and a main branch portion (102) where the suction branch pipes (61a, 61b, 61c) branch from the suction main pipe (55). (71) in order downstream from the connection,

In the main branch section (102), the suction branch pipe (61a) of the first compressor (1 la) set in advance among the compressors (11a, ib, 11c) is connected to the main curved section (101). ) Is located at the outermost periphery in the radius direction of curvature

A refrigeration apparatus characterized by that.

[3] A plurality of compressors (11a, l ib, 11c) connected in parallel to each other, and the compressors (11a, l ib, l)) having a refrigerant circuit (10) having an oil separator (70) for separating refrigeration oil from the discharged refrigerant,

In the main branch portion (102) where the suction branch pipes (61a, 61b, 61c) branch from the suction main pipe (55), a preset first of the compressors (11a, ib, 11c) is provided. 1 The suction branch pipe (61a) of the compressor (11a) is located at the bottom.

A refrigeration apparatus characterized by that.

[4] In claim 2,

The suction branch pipe (61a) of the first compressor (11a) is located at the lowermost part of the main branch part (102)

A refrigeration apparatus characterized by that.

[5] In claim 1,

The plurality of compressors (11a, l ib, 11c) is composed of first to third three compressors (11a, l ib, 11c),

The suction main pipe (55) includes a suction connection pipe (56) branched into a suction branch pipe (61b) of the second compressor (1 lb) and a suction branch pipe (61c) of the third compressor (11c). Branched to the suction branch pipe (61a) of the first compressor (11a),

The refrigeration oil flowing through the suction connection pipe (56) flows more from the suction branch pipe (61c) of the third compressor (11c) to the suction branch pipe (61b) of the second compressor (1 lb). Sub-drift means (120) for drifting the refrigerator oil in the connecting pipe (56) is provided.

A refrigeration apparatus characterized by that.

[6] In any one of claims 2 to 4,

The suction main pipe (55) is connected to the suction of the second compressor (lib) at the main branch (102). A suction connection pipe (56) having a sub-branch (104) branching to a branch pipe (61b) and a suction branch pipe (61c) of a third compressor (1 lc); and a suction pipe of the first compressor (11a) The suction connection pipe (56) branched to the branch pipe (61a) is provided with a sub-curved portion (103),

In the sub-branch portion (104), the suction branch pipe (61b) of the second compressor (l ib) has a sub-curved section (61c) rather than the suction branch pipe (61c) of the third compressor (1 lc). 103) located outside the radius of curvature

A refrigeration apparatus characterized by that.

[7] In any one of claims 2 to 4,

The main suction pipe (55) branches at the main branch (102) into the suction branch pipe (61b) of the second compressor (I ib) and the suction branch pipe (61c) of the third compressor (1 lc). Branching into a suction connecting pipe (56) having a secondary branching section (104) and a suction branching pipe (61a) of the first compressor (11a). 2 The suction branch pipe (61b) of the compressor (l ib) is located below the suction branch pipe (61c) of the third compressor (1 lc).

A refrigeration apparatus characterized by that.

[8] In claim 6,

The suction branch pipe (61b) of the second compressor (1 lb) is positioned below the suction branch pipe (61c) of the third compressor (11c) in the sub branch section (104).

A refrigeration apparatus characterized by that.

[9] In claim 2 or 4,

The main suction pipe (55) branches at the main branch (102) into the suction branch pipe (61b) of the second compressor (I ib) and the suction branch pipe (61c) of the third compressor (1 lc). Branching into a suction connection pipe (56) having a secondary branching section (104) and a suction branch pipe (61a) of the first compressor (11a). In the sub-branch portion (104), the suction branch pipe (61b) of the second compressor (l ib) is more than the suction branch pipe (61c) of the third compressor (11c). 55) is located outside the radius of curvature of the main curved portion (101)

A refrigeration apparatus characterized by that.

[10] In any one of claims 1 to 3,

Oil leveling means (72, 73) is provided for supplying the refrigeration oil stored in the dome of the first compressor (11a) to the other compressors (lib, 11c).

A refrigeration apparatus characterized by.

[11] In any one of claims 1 to 3,

Oil leveling means (72, 73, 74) for leveling the refrigeration oil stored in the dome of each compressor (11a, ib, 11c) is provided.

A refrigeration apparatus characterized by that.

[12] In claim 5,

A first average for supplying the refrigerating machine oil stored in the dome of the first compressor (11a) to the suction connection pipe (56) or the suction branch pipe (61b) of the second compressor (lib). An oil pipe (72) and a second oil equalizing pipe for supplying the refrigeration oil stored in the dome of the second compressor (lib) to the suction branch pipe (61c) of the third compressor (11c) ( 73) and a third oil leveling pipe (74) for supplying the refrigeration oil stored in the dome of the third compressor (11c) to the suction main pipe (55) or the oil return pipe (71). /!

A refrigeration apparatus characterized by that.

[13] In any one of claims 1 to 3,

The first compressor (11a) is a compressor having a fixed operating capacity.

A refrigeration apparatus characterized by that.

[14] In any one of claims 1 to 13,

Each of the compressors (11a, l ib, 11c) is configured to store refrigeration oil in the high-pressure space inside the dome.

A refrigeration apparatus characterized by that.

[15] In any one of claims 1 to 3,

In each of the intake branch pipes (61a, 61b, 61c) of the compressors (11a, ib, 11c), a part of the liquid refrigerant flowing through the high-pressure side liquid pipe (84) in the refrigerant circuit (10) Connected to the liquid intake pipes (86, 86a, 86b, 86c) that lead the pipes to the intake branch pipes (61a, 61b, 61c).

A refrigeration apparatus characterized by that.

[16] In any one of claims 1 to 3,

An oil recovery pipe (75, 76, 77) having one end connected to the suction branch pipe (61a, 61b, 61c) of each compressor (11a, ib, 11c) and the other end connected to each other is provided.

A refrigeration apparatus characterized by that.

[17] A plurality of compressors (11a, l ib, 11c) connected in parallel to each other, and the compressors (11a, l ib,

A refrigeration apparatus characterized by that.

[18] In claim 16,

The intake branch pipe (61a, 61b, 61c) includes an inclined portion (59) inclined upward from a predetermined position in the middle of the intake branch pipe (61a, 61b, 61c) toward the downstream side, and the inclined portion An oil reservoir (58) formed on the upstream side of (59),

One end of the oil recovery pipe (75, 76, 77) is connected to the oil reservoir (58).

[19] In claim 17,

The suction branch pipe (61a, 61b, 61c) is located in the middle of the suction branch pipe (61a, 61b, 61c). An inclined portion (59) inclined upward from the fixed position toward the downstream side, and an oil reservoir (58) formed on the upstream side of the inclined portion (59),

[20] In claim 6,

A refrigeration apparatus characterized by that.

[21] In claim 7,

A refrigeration apparatus characterized by that.