JP2010156499A - Refrigerating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain high COP regardless of changes in operating conditions, in a refrigerating device including a compressor constituted of a plurality of compression mechanisms mechanically connected by one drive shaft and performing a two-stage compression refrigerating cycle. <P>SOLUTION: An air conditioner (1) including a refrigerant circuit (10) to which the compressor (11) having three rotary type compression mechanisms (31, 32, 33) connected by one drive shaft (35) is connected and performing the two-stage compression refrigerating cycle includes switching mechanisms (18, 19) each changing a suction volume ratio which is a ratio of a suction volume between a low stage side compression mechanism and a high stage side compression mechanism of the compressor (11). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a refrigeration apparatus that performs a two-stage compression refrigeration cycle, and particularly relates to a refrigeration apparatus provided with a compressor in which a plurality of compression mechanisms are connected by a single drive shaft.

Conventionally, as a refrigeration apparatus that performs a two-stage compression refrigeration cycle, for example, a compressor in which two compression mechanisms are connected to one drive shaft is used (see, for example, Patent Document 1). In the compressor of the refrigeration apparatus, one compression mechanism is a low-stage compression mechanism, and the other compression mechanism is a high-stage compression mechanism.
JP 2000-87892 A

  By the way, in the refrigeration apparatus that performs the two-stage compression refrigeration cycle as described above, the results are based on the value of the refrigerant pressure (hereinafter referred to as “intermediate pressure”) between the low-stage compression mechanism and the high-stage compression mechanism. The coefficient (COP) changes. However, the intermediate pressure at which a high COP is obtained varies depending on operating conditions and the like. Therefore, it is preferable to control the intermediate pressure to an appropriate value according to the operating conditions.

  However, the above-described refrigeration apparatus is configured such that one compression mechanism is always used as the low-stage compression mechanism and the other compression mechanism is always used as the high-stage compression mechanism. Therefore, the ratio of the suction volume between the low-stage compression mechanism and the high-stage compression mechanism is always constant, and the intermediate pressure cannot be controlled to an appropriate value according to the operating conditions. Therefore, in the refrigeration apparatus provided with such a compressor, there is a problem that a high COP cannot be obtained if the operating condition is out of a predetermined range.

  The present invention has been made in view of such points, and an object of the present invention is to perform a two-stage compression refrigeration cycle provided with a compressor in which a plurality of compression mechanisms are connected by a single drive shaft. In the apparatus, a high COP is obtained regardless of changes in operating conditions.

  The first invention is a compressor in which a plurality of rotary type compression mechanisms (31, 32, 33) each having one cylinder chamber (C1, C2, C3) are connected by a single drive shaft (35). A refrigeration apparatus including a refrigerant circuit (10) having (11) and performing a two-stage compression refrigeration cycle, wherein the compressor (11) includes three compression mechanism parts (31, 32, 33), Suction volume ratio changing means (2) for changing the suction volume ratio, which is the ratio of the suction volume between the stage side compression mechanism and the high stage side compression mechanism, is provided.

  In the first invention, the compressor (11) includes three compression mechanisms (31, 32, 33). Therefore, in the compressor (11), at least one of the three compression mechanism sections (31, 32, 33) is used as a low-stage compression mechanism, and at least one remaining is used as a high-stage compression mechanism. Thus, the refrigerant is compressed in two stages. The refrigeration apparatus further includes suction volume ratio changing means (2). Therefore, in this refrigeration apparatus, the suction volume ratio can be changed by the suction volume ratio changing means (2).

  According to a second invention, in the first invention, the suction volume ratio changing means (2) changes the connection relationship of the three compression mechanism portions (31, 32, 33), thereby changing the suction volume ratio. change.

  In the second invention, three compression mechanism portions are provided, and the suction volume ratio can be changed by changing the connection relation of the three compression mechanism portions (31, 32, 33).

  In a third aspect based on the second aspect, the suction volume ratio changing means (2) includes two compression mechanisms used as a low-stage compression mechanism among the three compression mechanism portions (31, 32, 33). A switching mechanism (18, 19) for switching between a state in which the mechanism units (31, 32) are connected in series and a state in which the mechanism portions are connected in parallel is provided.

  In the third invention, the two compression mechanism parts (31, 32) used as the low-stage compression mechanism are connected in series by the switching mechanism (18, 19) of the suction volume ratio changing means (2). The suction volume ratio is changed by switching between the states connected in parallel.

  Specifically, when the two compression mechanism portions (31, 32) are connected in parallel, the suction volume of the low-stage compression mechanism is the sum of the suction volumes of the two compression mechanism portions (31, 32). On the other hand, when the two compression mechanism portions (31, 32) are connected in series, the suction volume of the low-stage compression mechanism is the upstream compression mechanism portion (31 of the two compression mechanism portions (31, 32)). ) Intake volume. Therefore, when the two compression mechanisms (31, 32) are used as a low-stage compression mechanism and the connection relationship is changed from parallel to serial, the suction volume ratio increases, while the serial volume is changed from parallel to parallel. In this case, the suction volume ratio becomes small.

  In a fourth aspect based on the second aspect, the suction volume ratio changing means (2) includes two compression mechanisms used as a high-stage compression mechanism among the three compression mechanism portions (31, 32, 33). A switching mechanism (90, 91) is provided for switching between a state in which the mechanism units (32, 33) are connected in series and a state in which the mechanism portions are connected in parallel.

  In the fourth invention, the switching mechanism (90, 91) of the suction volume ratio changing means (2) connects the two compression mechanism portions (32, 33) used as the high-stage compression mechanism in series. The suction volume ratio is changed by switching between the states connected in parallel.

  Specifically, when the two compression mechanism parts (32, 33) are connected in parallel, the suction volume of the high-stage compression mechanism is the sum of the suction volumes of the two compression mechanism parts (32, 33). On the other hand, when the two compression mechanism portions (32, 33) are connected in series, the suction volume of the high-stage compression mechanism is the upstream compression mechanism portion (32 of the two compression mechanism portions (32, 33)). ) Intake volume. Therefore, when the connection relationship of the two compression mechanisms (32, 33) is changed from parallel to serial, the suction volume ratio decreases, whereas when the connection relationship is changed from serial to parallel, the suction volume ratio increases. .

  In a fifth aspect based on the second aspect, any two compression mechanism portions (31, 32) of the three compression mechanism portions (31, 32, 33) are configured to have different suction volumes. The suction volume ratio changing means (2) has a switching mechanism (92, 93) for changing the connection relationship between the two compression mechanisms (31, 32) having different suction volumes.

  In the fifth aspect of the invention, the two compression mechanism portions (31, 31) having different suction volumes among the three compression mechanism portions (31, 32, 33) are switched by the switching mechanism (92, 93) of the suction volume ratio changing means (2). , 32) is switched, the suction volume of at least one of the low-stage compression mechanism and the high-stage compression mechanism changes. Thereby, the suction volume ratio is changed.

  According to a sixth invention, in the fifth invention, one of the two compression mechanism portions (31, 32) is used as a low-stage compression mechanism and the other is used as a high-stage compression mechanism. ing.

  In the sixth invention, the compression mechanism portion used as the low-stage compression mechanism of the three compression mechanism portions (31, 32, 33) by the switching mechanism (92, 93) of the suction volume ratio changing means (2). When the connection relationship between (31) and the compression mechanism section (32) used as the high-stage compression mechanism is switched, the compression mechanism section (31) used as the low-stage compression mechanism before switching is switched to the high-stage side. On the other hand, the compression mechanism part (32) used as the high-stage compression mechanism is used as the low-stage compression mechanism. Accordingly, since the suction volume of at least one of the low stage side compression mechanism and the high stage side compression mechanism is changed, the suction volume ratio is changed.

  In a seventh aspect based on the first aspect, the suction volume ratio changing means (2) is configured such that the refrigerant is compressed in all the compression mechanism portions of the three compression mechanism portions (31, 32, 33). The refrigerant is compressed in two of the three compression mechanism sections (31, 32, 33) in the above state, while the suction side and the discharge side are substantially separated in the remaining one compression mechanism section. And a switching mechanism (94, 95, 96, 97, 98) for switching to a second state in which the refrigerant reaches an equal pressure state and passes without being compressed.

  In the seventh invention, when the switching mechanism (94, 95, 96, 97, 98) of the suction volume ratio changing means (2) is switched from the first state to the second state, the three compression mechanism portions (31 , 32, 33), the suction side and the discharge side of any one of the compression mechanism portions are in a substantially equal pressure state, and the refrigerant is not compressed in the compression mechanism portion. Thereby, since the suction volume of the low stage side compression mechanism or the high stage side compression mechanism changes, the suction volume ratio is changed.

  In an eighth aspect based on the seventh aspect, the switching mechanism (94, 95, 96) is any one of the three compression mechanism portions (31, 32, 33) in the first state. While the two compression mechanism portions are connected in parallel, in the second state, the suction side and the discharge side of one compression mechanism portion of the two compression mechanism portions connected in parallel in the first state, Are configured to communicate with each other.

  In the eighth invention, when the first state is switched to the second state by the switching mechanism (94, 95, 96) of the suction volume ratio changing means (2), they are connected in parallel in the first state. In one of the two compression mechanism portions, the suction side and the discharge side are in communication with each other and are in substantially the same pressure state, so that the refrigerant passes through without being compressed. Thereby, since the suction volume of the low stage side compression mechanism or the high stage side compression mechanism changes, the suction volume ratio is changed.

  In a ninth aspect based on the seventh aspect, any two compression mechanism portions (32, 33) of the three compression mechanism portions (31, 32, 33) are configured to have different suction volumes. In the first state, the switching mechanism (97, 98) is configured such that the two compression mechanism portions (32, 33) having different suction volumes are connected in series so that both the compression mechanism portions (32, 33) are low. While used as a stage-side compression mechanism or a high-stage side compression mechanism, in the second state, the upstream compression of the two compression mechanism parts (32, 33) connected in series in the first state. The suction side and the discharge side of the mechanism part (32) are configured to communicate with each other.

  In the ninth invention, when the first state is switched to the second state by the switching mechanism (97, 98) of the suction volume ratio changing means (2), the first stage is connected in series and the lower stage side Of the two compression mechanism portions (32, 33) used as the compression mechanism or the high-stage compression mechanism, the upstream compression mechanism portion (32) substantially communicates with the suction side and the discharge side. Since the pressure is equal, the refrigerant passes through without being compressed. Thereby, since the suction volume of the low stage side compression mechanism or the high stage side compression mechanism changes, the suction volume ratio is changed.

  In a tenth aspect based on the first aspect, the three compression mechanism sections (31, 32, 33) include the first compression mechanism section (31), the second compression mechanism section (32), and the third The suction volume ratio changing means (2) is connected in series in the order of the compression mechanism section (33), and the suction volume ratio changing means (2) supplies the refrigerant between the first compression mechanism section (31) and the second compression mechanism section (32). The first compression mechanism (31) is cooled and used as the low-stage compression mechanism, while the second compression mechanism (32) and the third compression mechanism (33) are used as the high-stage compression mechanism. The first compression mechanism section (32) and the third compression mechanism section (33) are cooled to cool the refrigerant between the first compression mechanism section (32) and the third compression mechanism section (33). A switching mechanism (98) for switching to a second state in which the second compression mechanism (32) is used as a low-stage compression mechanism while the third compression mechanism (33) is used as a high-stage compression mechanism. Have.

  In the tenth invention, the suction volume ratio is changed by changing the position of the intermediate stage of the compressor (11) by the switching mechanism (98) of the suction volume ratio changing means (2).

  Specifically, in the first state, the suction volume of the low-stage compression mechanism is the suction volume of the first compression mechanism section (31), and the suction volume of the high-stage compression mechanism is the second compression mechanism section ( 32) suction volume. On the other hand, in the second state, the suction volume of the low-stage compression mechanism is the suction volume of the first compression mechanism section (31), and the suction volume of the high-stage compression mechanism is that of the third compression mechanism section (33). Inhalation volume. Therefore, by switching to the first state or the second state by the switching mechanism (98), the suction volume of the high-stage compression mechanism is changed, and the suction volume ratio is changed.

  In an eleventh aspect based on any one of the first to tenth aspects, the refrigerant flowing through the refrigerant circuit (10) is carbon dioxide.

  In the eleventh aspect of the invention, the carbon dioxide as the refrigerant charged in the refrigerant circuit (10) is sucked into the low-stage compression mechanism and compressed until it reaches an intermediate pressure state, and then sucked into the high-stage compression mechanism. And compressed until a high pressure state higher than the critical pressure is reached.

  According to the present invention, since the suction volume ratio changing means (2) is provided, the intermediate pressure is changed (increased or lowered) so as to obtain a high COP by changing the suction volume ratio in accordance with the change of the operating condition. Can be reduced). Therefore, according to the present invention, a high COP can be obtained regardless of changes in operating conditions.

  Further, according to the second invention, since the three compression mechanism portions are provided, the connection relationship between the three compression mechanism portions (31, 32, 33) without changing the shape of the cylinder chamber of the compression mechanism portion. The suction volume ratio can be easily changed by changing.

  Further, according to the third invention, the switching mechanism (18, 19) of the suction volume ratio changing means (2) is used as the low-stage compression mechanism among the three compression mechanism parts (31, 32, 33). The suction volume ratio can be easily changed by switching the connection relationship between the two compression mechanism sections (31, 32) to be serial or parallel.

  Further, according to the fourth invention, the switching mechanism (90, 91) of the suction volume ratio changing means (2) is used as the higher stage compression mechanism of the three compression mechanism parts (31, 32, 33). The suction volume ratio can be easily changed by switching the connection relationship between the two compression mechanism sections (32, 33) to be serial or parallel.

  According to the fifth and sixth inventions, the connection relationship between the two compression mechanism portions (31, 32) having different suction volumes is changed by the switching mechanism (92, 93) of the suction volume ratio changing means (2). By doing so, the suction volume ratio can be easily changed.

  Further, according to the seventh invention, all the compression mechanisms (31, 32, 33) are compressed by the switching mechanism (94, 95, 96, 97, 98) of the suction volume ratio changing means (2). The refrigerant is compressed in the first state where the refrigerant is compressed in the mechanism part and in two of the three compression mechanism parts (31, 32, 33), while the remaining one compression mechanism part The suction volume ratio can be easily changed by switching between the second state in which the refrigerant passes without being compressed.

  According to the tenth invention, the suction volume ratio can be easily changed by changing the position of the intermediate stage of the compressor (11) by the suction volume ratio changing means (2).

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, an air conditioner will be described as an example of the refrigeration apparatus according to the present invention.

Embodiment 1 of the Invention
-Overall configuration-
As shown in FIG. 1, the air conditioner (1) includes a refrigerant circuit (10) that performs a two-stage compression refrigeration cycle. The refrigerant circuit (10) includes a compressor (11), an outdoor heat exchanger (12), a first expansion valve (13), a gas-liquid separator (14), and a second expansion valve (15). And an indoor heat exchanger (16). The refrigerant circuit (10) includes a four-way valve (17) for switching between heating operation and cooling operation, and a first three-way valve (18) and a first three-way valve constituting a switching mechanism for suction volume ratio changing means (2) described later. Two three-way valves (19) are provided.

  Although the detailed configuration of the compressor (11) will be described later, the compressor (11) includes an airtight container-like casing (40). In the casing (40), there are three compression mechanism parts (31, 32, 33), an electric motor (34) for driving the three compression mechanism parts (31, 32, 33), and three compressions. The mechanism (31, 32, 33) and the drive shaft (35) to which the electric motor (34) is connected are accommodated. Although details will be described later, in the compressor (11), at least one of the three compression mechanism parts (31, 32, 33) is used as a low-stage compression mechanism, while the remaining compression mechanism parts At least one of them is used as a high-stage compression mechanism and connected to the refrigerant circuit (10) so as to perform a two-stage compression refrigeration cycle.

  The casing (40) includes a first suction pipe (51), a first discharge pipe (52), a second suction pipe (53), a second discharge pipe (54), so as to penetrate the casing (40). A third suction pipe (55) and a high-pressure discharge pipe (56) are provided.

  The first suction pipe (51) is connected to the suction side of the first compression mechanism section (31), and the first discharge pipe (52) is connected to the discharge side of the first compression mechanism section (31). Yes. The second suction pipe (53) is connected to the suction side of the second compression mechanism section (32), and the second discharge pipe (54) is connected to the discharge side of the second compression mechanism section (32). Has been. Further, the third suction pipe (55) is connected to the suction side of the third compression mechanism (33), while the discharge side of the third compression mechanism (33) is the internal space (S1 of the casing (40)). ) Is open. The high-pressure discharge pipe (56) is provided in the upper part of the casing (40), and the inner end thereof opens in the internal space (S1) of the casing (40).

  The four-way valve (17) includes first to fourth ports (P1, P2, P3, P4). The first port (P1) and the second port (P2) communicate with each other and the third port (P3). 1 and the fourth port (P4) communicate with each other (solid line in FIG. 1), the first port (P1) and the fourth port (P4) communicate with each other and the second port (P2) and the third port (P4). It is configured to be switchable to a second position (broken line in FIG. 1) where the port (P3) communicates. The four-way valve (17) is switched between a first position and a second position by a controller (not shown).

  The first port (P1) of the four-way valve (17) is connected to the other end of the high-pressure gas pipe (21) having one end connected to the high-pressure discharge pipe (56). One end of the first gas pipe (22) is connected to the second port (P2) of the four-way valve (17). The other end of the first gas pipe (22) is connected to the gas side end of the outdoor heat exchanger (12).

  The outdoor heat exchanger (12) is a cross fin type fin-and-tube heat exchanger. One end of the first liquid pipe (23a) is connected to the liquid side end of the outdoor heat exchanger (12), and the gas-liquid separator (14) is connected to the other end of the first liquid pipe (23a). Has been. The first liquid pipe (23a) is provided with a first expansion valve (13).

  One end of a second liquid pipe (23b) is connected to the gas-liquid separator (14). The other end of the second liquid pipe (23b) is connected to the liquid side end of the indoor heat exchanger (16). The second liquid pipe (23b) is provided with a second expansion valve (15).

  The indoor heat exchanger (16) is a cross-fin type fin-and-tube heat exchanger. One end of the second gas pipe (24) is connected to the gas side end of the indoor heat exchanger (16), and the other end of the second gas pipe (24) is the fourth port of the four-way valve (17). (P4) connected.

  One end of a low-pressure gas pipe (25) is connected to the third port (P3) of the four-way valve (17). The other end of the low pressure gas pipe (25) is connected to the first suction pipe (51). One end of the low-pressure gas branch pipe (25a) is connected to the middle part of the low-pressure gas pipe (25), and the other end of the low-pressure gas branch pipe (25a) is the first port of the second three-way valve (19). Connected to (P1).

  One end of a first communication pipe (26) is connected to the first discharge pipe (52), and the other end of the first communication pipe (26) is connected to a second port ( Connected to P2). One end of the second connecting pipe (27) is connected to the third port (P3) of the first three-way valve (18), and the other end of the second connecting pipe (27) is connected to the second three-way valve. It is connected to the third port (P3) of (19). In addition, one end of a third connecting pipe (28) is connected to the second port (P2) of the second three-way valve (19), and the other end of the third connecting pipe (28) is connected to the second suction pipe ( 53) is connected.

  One end of a fourth connecting pipe (29) is connected to the second discharge pipe (54), and the other end of the fourth connecting pipe (29) is connected to the third suction pipe (55). . One end of a fourth connecting / merging pipe (29a) is connected to the middle part of the fourth connecting pipe (29), and the other end of the fourth connecting / merging pipe (29a) is connected to the first three-way valve (18). Connected to the first port (P1). One end is connected to the gas-liquid separator (14) on the third suction pipe (55) side of the connection part of the fourth communication junction pipe (29a) in the middle of the fourth communication pipe (29). The other end of the injection pipe (20) is connected. The injection pipe (20) cools the refrigerant being compressed by joining the gas refrigerant separated by the gas-liquid separator (14) with the refrigerant being compressed in the compressor (11). The cooling means is configured.

  The first three-way valve (18) and the second three-way valve (19) include first to third ports (P1, P2, P3), respectively, and the first port (P1) and the second port (P2). And a second position where the second port (P2) and the third port (P3) communicate with each other. The first three-way valve (18) and the second three-way valve (19) are switched between a first position and a second position by a controller (not shown).

  The air conditioner (1) also changes the ratio of the suction volume between the low-stage compression mechanism and the high-stage compression mechanism (hereinafter simply referred to as “suction volume ratio”) of the compressor (11). A suction volume ratio changing means (2) is provided. In the first embodiment, the suction volume ratio changing means (2) changes the connection ratio of the three compression mechanism portions (31, 32, 33) of the compressor (11) to change the suction volume ratio. Is configured to change.

  Specifically, the suction volume ratio changing means (2) includes a first compression mechanism part (31) and a second compression mechanism part (32) used as a low-stage compression mechanism, connected in series. A switching mechanism for switching between the state and the second state connected in parallel is provided. In the first embodiment, the switching mechanism is configured by the first three-way valve (18) and the second three-way valve (19), and is in the first state as the operating condition of the air conditioner (1) changes. And the second state.

<Compressor configuration>
As shown in FIG. 2, the compressor (11) of the present embodiment is a so-called hermetic compressor, and as described above, the first compression mechanism section (31) and the second compression mechanism section (32). A third compression mechanism section (33), an electric motor (34) for driving the three compression mechanism sections (31, 32, 33), three compression mechanism sections (31, 32, 33), and an electric motor A drive shaft (35) that couples (34) is accommodated in one casing (40).

  The casing (40) is formed in a vertically long cylindrical closed container shape. Specifically, the casing (40) includes a main body cylinder portion (41), an upper end plate (42), and a lower end plate (43). The main body cylinder portion (41) is formed in a hollow cylindrical shape whose both ends are open ends. In the casing (40), the upper end of the main body tube portion (41) is closed by the upper end plate (42), and the lower end of the main body tube portion (41) is closed by the lower end plate (43).

  In the casing (40), the electric motor (34) is disposed above the three compression mechanisms (31, 32, 33). The drive shaft (35) that connects the three compression mechanism sections (31, 32, 33) and the electric motor (34) is disposed in a posture in which the axial direction is the vertical direction.

  The electric motor (34) includes a rotor (34a) and a stator (34b). The rotor (34a) is fixed to the upper end of the drive shaft (35), while the stator (34b) is fixed to the main body cylinder (41) of the casing (40).

  The drive shaft (35) includes a main shaft portion (35a), a first eccentric portion (35b), a second eccentric portion (35c), and a third eccentric portion (35d). The three eccentric portions (35b, 35c, 35d) are formed in portions of the drive shaft (35) that pass through the respective compression mechanism portions (31, 32, 33). In the drive shaft (35), the second eccentric portion (35c) is disposed above the first eccentric portion (35b), and the third eccentric portion (35d) is disposed above the second eccentric portion (35c). . The three eccentric parts (35b, 35c, 35d) are all formed in a cylindrical shape having an outer diameter larger than that of the main shaft part (35a), and the three eccentric parts (35b, 35c, 35d) have the same outer diameter. Further, the shaft centers of the eccentric portions (35b, 35c, 35d) are eccentric with respect to the shaft center of the main shaft portion (35a). The eccentric direction of the first eccentric portion (35b) with respect to the main shaft portion (35a) and the eccentric direction of the second eccentric portion (35c) with respect to the main shaft portion (35a) are shifted by 180 ° in the rotational direction of the drive shaft (35). Yes. The eccentric direction of the second eccentric portion (35c) with respect to the main shaft portion (35a) and the eccentric direction of the third eccentric portion (35d) with respect to the main shaft portion (35a) are 180 ° in the rotational direction of the drive shaft (35). It is off.

  The three compression mechanisms (31, 32, 33) are integrally formed, and from the bottom to the top, the cover plate (36), the rear head (37r), the first cylinder (61), and the first middle plate (38 ), The second cylinder (71), the second middle plate (39), the third cylinder (81), and the front head (37f) are laminated in this order. Although illustration is omitted, the three compression mechanism portions (31, 32, 33) are fastened to each other by a plurality of bolts provided so as to penetrate through the respective stacked members.

  Each of the three cylinders (61, 71, 81) is a thick cylindrical member, and both end surfaces (upper end surface and lower end surface in FIG. 2) are flat surfaces parallel to each other. A drive shaft (35) is inserted into the three cylinders (61, 71, 81). The first eccentric part (35b) of the drive shaft (35) is located inside the first cylinder (61), and the second eccentric part (35c) of the drive shaft (35) is located inside the second cylinder (71). The third eccentric portion (35d) of the drive shaft (35) is located inside the third cylinder (81).

  The first middle plate (38) and the second middle plate (39) are constituted by flat plate members that are slightly thinner than the three cylinders (61, 71, 81). The first middle plate (38) is sandwiched between the first cylinder (61) and the second cylinder (71), the lower surface is in close contact with the first cylinder (61), and the upper surface is attached to the second cylinder (71). It is in close contact. On the other hand, the second middle plate (39) is sandwiched between the second cylinder (71) and the third cylinder (81), the lower surface is in close contact with the second cylinder (71), and the upper surface is the third cylinder (81). ). The first middle plate (38) and the second middle plate (39) are formed with through holes penetrating in the thickness direction, and the drive shaft (35) is inserted through the through holes.

  The front head (37f) includes a flat end plate portion and a cylindrical boss portion formed on the upper end of the end plate portion. The surface opposite to the boss portion of the end plate portion is formed flat and is in close contact with the third cylinder (81). The front head (37f) has a through hole extending in the axial direction of the boss portion from the boss portion to the end plate portion, and the main shaft portion (35a) of the drive shaft (35) is formed in the through hole. It is inserted.

  The rear head (37r) is formed of a flat plate member that is thicker than the first cylinder (61), and its upper surface is in close contact with the first cylinder (61). A through hole penetrating in the thickness direction is formed in the rear head (37r), and the drive shaft (35) is inserted through the through hole.

  The cover plate (36) is formed of a relatively thin flat plate member. The cover plate (36) is provided so as to cover the lower surface of the rear head (37r).

  A first piston (62) having a cylindrical shape is accommodated in the first cylinder (61), and the first cylinder is interposed between the inner peripheral surface of the first cylinder (61) and the outer peripheral surface of the first piston (62). A chamber (C1) is formed. The upper end of the first cylinder chamber (C1) is closed by the lower surface of the first middle plate (38), and the lower end of the first cylinder chamber (C1) is closed by the upper surface of the rear head (37r). The outer peripheral surface of the first piston (62) is in sliding contact with the inner peripheral surface of the first cylinder (61) at one place in the circumferential direction. The first piston (62) engaged with the first eccentric portion (35b) rotates eccentrically with its outer peripheral surface in contact with the inner peripheral surface of the first cylinder (61).

  A second piston (72) is accommodated in the second cylinder (71), and a second cylinder chamber (between the inner peripheral surface of the second cylinder (71) and the outer peripheral surface of the second piston (72) is provided. C2) is formed. The upper end of the second cylinder chamber (C2) is closed by the lower surface of the second middle plate (39), and the lower end of the second cylinder chamber (C2) is closed by the upper surface of the first middle plate (38). The outer peripheral surface of the second piston (72) is in sliding contact with the inner peripheral surface of the second cylinder (71) at one place in the circumferential direction. The second piston (72) engaged with the second eccentric portion (35c) rotates eccentrically with its outer peripheral surface in contact with the inner peripheral surface of the second cylinder (71).

  Further, the third cylinder (81) accommodates a third piston (82), and a third cylinder chamber (81) is provided between the inner peripheral surface of the third cylinder (81) and the outer peripheral surface of the third piston (82). C3) is formed. The upper end of the third cylinder chamber (C3) is closed by the lower surface of the front head (37f), and the lower end of the third cylinder chamber (C3) is closed by the upper surface of the second middle plate (39). The outer peripheral surface of the third piston (82) is in sliding contact with the inner peripheral surface of the third cylinder (81) at one place in the circumferential direction. The third piston (82) engaged with the third eccentric portion (35d) rotates eccentrically with its outer peripheral surface in contact with the inner peripheral surface of the third cylinder (81).

  FIG. 3 is a cross-sectional view of the compression mechanism section (31, 32, 33). The second compression mechanism section (32) is different from the configuration of the compression mechanism section shown in FIG. 3 in that a discharge space and a discharge port to be described later are formed in the second cylinder (71). Are configured in substantially the same manner, the second compression mechanism section (32) will also be described with reference to FIG. In FIG. 3, the reference numerals without parentheses indicate the reference numerals of the first compression mechanism section (31), the reference numerals on the left side in parentheses indicate the reference numerals of the second compression mechanism section (32), and the reference numerals on the right side in parentheses The code | symbol of a 3rd compression mechanism part (33) is represented. This also applies to FIG.

  As shown in FIG. 3, blades (63, 73, 83) are integrally formed on each of the first piston (62), the second piston (72), and the third piston (82). Each blade (63, 73, 83) is formed in a flat plate shape extending outward from the outer peripheral surface of the piston (62, 72, 82). Each cylinder chamber (C1, C2, C3) has a low pressure chamber (C1-Lp, C2-Lp, C3-Lp) as a first chamber and a high pressure chamber as a second chamber by the blades (63, 73, 83). (C1-Hp, C2-Hp, C3-Hp).

  Also, blade grooves (64, 74, 84) for inserting the blades (63, 73, 83) into the first cylinder (61), the second cylinder (71) and the third cylinder (81), respectively. Is formed. Bushings (65, 75, 85) for supporting the blades (63, 73, 83) are inserted into the blade grooves (64, 74, 84) of the cylinders (61, 71, 81).

  Two bushes (65, 75, 85) are provided for each cylinder (61, 71, 81), and the blades (63, 73, 83) are sandwiched between the bushes (65, 75, 85). Each bush (65,75,85) has a flat front surface in sliding contact with the side surface of the blade (63,73,83), and a circular back surface in sliding contact with the cylinder (61,71,81). . The bush (65, 75, 85) is rotatable with respect to the cylinder (61, 71, 81), and the blade (63, 73, 83) is movable with respect to the bush (65, 75, 85). It has become. The pair of bushes (65, 75, 85) provided in each cylinder (61, 71, 81) may be partially connected to form an integral structure.

  With this configuration, when the drive shaft (35) is driven and each piston (62, 72, 82) rotates eccentrically with respect to the axis of the drive shaft (35), the piston (62, 72, 82) and The integrally formed blade (63, 73, 83) swings around the center point of the bush (65, 75, 85) while moving forward and backward along the bush (65, 75, 85).

  A suction port (66, 76, 86) is formed in each cylinder (61, 71, 81). The suction port (66, 76, 86) is formed so as to extend in the radial direction and communicate with the inside and outside of the cylinder (61, 71, 81). The first suction pipe (51) is connected to the suction port (66) formed in the first cylinder (61), and the second suction port (76) formed in the second cylinder (71). A pipe (53) is connected, and the third suction pipe (55) is connected to a suction port (86) formed in the third cylinder (81).

  On the other hand, as shown in FIG. 2, the discharge space (67) and the discharge space (67) and the first cylinder chamber (C1) communicate with the rear head (37r) adjacent to the first cylinder (61). A discharge port (68) is formed. A discharge valve (69) is attached to the discharge port (68), and the first discharge pipe (52) is connected to the discharge space (67).

  The front head (37f) adjacent to the third cylinder (81) is formed with a discharge space (87) and a discharge port (88) communicating the discharge space (87) and the third cylinder chamber (C3). Has been. A discharge valve (89) is attached to the discharge port (88), and the discharge space (87) opens into the internal space (S1) of the casing (40).

  Although not shown, the second cylinder (71) is also formed with a discharge space and a discharge port that communicates the discharge space with the second cylinder chamber (C2). The discharge port is formed so as to penetrate the inside and outside of the second cylinder (71), and a discharge valve is attached to the outer end portion thereof. The second discharge pipe (54) is connected to the discharge space.

  With the above configuration, when the electric motor (34) is started, in the first compression mechanism (31), the rotation of the rotor (34a) is caused by the first piston (35b) via the first eccentric part (35b) of the drive shaft (35). 62). Accordingly, the first piston (62) revolves while swinging with respect to the first cylinder (61), and the first compression mechanism (31) performs a predetermined compression operation.

  Specifically, in the first cylinder chamber (C1), the drive shaft (35) rotates clockwise from the state of FIG. 4 (a) and the suction port (66) is closed by the piston (62). As the drive shaft (35) further rotates from the state and changes to the state of FIGS. 4 (b) to (a), the volume of the low-pressure chamber (C1-Lp) increases, and the refrigerant flows into the first suction pipe. (51) is sucked into the low pressure chamber (C1-Lp) through the suction port (66).

  When the drive shaft (35) rotates once and the suction port (66) is closed again by the piston (62), the suction of the refrigerant into the low pressure chamber (C1-Lp) is completed, and the low pressure chamber (C1 -Lp) is the high pressure chamber (C1-Hp) in which the refrigerant is compressed. At this time, a new low-pressure chamber (C1-Lp) is formed across the blade (63). When the drive shaft (35) further rotates, the suction of the refrigerant is repeated in the low pressure chamber (C1-Lp), while the volume of the high pressure chamber (C1-Hp) decreases, and the high pressure chamber (C1-Hp) The refrigerant is compressed. When the pressure in the high pressure chamber (C1-Hp) reaches a preset value and the differential pressure from the discharge space (67) reaches a set value, the discharge valve (69) opens and the refrigerant in the high pressure chamber (C1-Hp) Flows out to the first discharge pipe (52) through the discharge port (68) and the discharge space (67).

  In the second compression mechanism section (32), the refrigerant is compressed in the same manner as in the first compression mechanism section (31). In other words, the refrigerant sucked from the second suction pipe (53) into the low pressure chamber (C2-Lp) of the second cylinder chamber (C2) is compressed in the high pressure chamber (C2-Hp) and is transferred to the second discharge pipe (54). leak.

  In the third compression mechanism (33), the refrigerant is compressed in the same manner as in the first compression mechanism (31). In other words, the refrigerant sucked from the third suction pipe (55) into the low pressure chamber (C3-Lp) of the third cylinder chamber (C3) is compressed in the high pressure chamber (C3-Hp) and the internal space of the casing (40) ( To S1).

  In the first embodiment, the suction volume (push volume) V1 of the first compression mechanism (31), the suction volume (push volume) V2 of the second compression mechanism (32), and the third compression mechanism ( The compression mechanism portions (31, 32, 33) are designed so that a relationship of V1> V2> V3 is established between the suction volume (displacement volume) V3 of (33).

-Driving action-
Next, the operation of the air conditioner (1) will be described. The air conditioner (1) can be switched between the following cooling operation and heating operation.

(Cooling operation)
As shown in FIG. 5, when the compressor (11) is started with the four-way valve (17) set to the first position, the outdoor heat exchanger (12) is connected to the radiator in the refrigerant circuit (10). On the other hand, a two-stage compression refrigeration cycle in which the indoor heat exchanger (16) serves as an evaporator is performed. In this two-stage compression refrigeration cycle, the high pressure of the two-stage compression refrigeration cycle is higher than the critical pressure of carbon dioxide. This is the same in the heating operation described later.

  Specifically, when the compressor (11) is started, the high-pressure gas refrigerant compressed in the compressor (11) flows into the outdoor heat exchanger (12) via the four-way valve (17). In the outdoor heat exchanger (12), the high-pressure gas refrigerant exchanges heat with air and dissipates heat to be cooled.

  The refrigerant cooled in the outdoor heat exchanger (12) is depressurized to an intermediate pressure by the first expansion valve (13), and then separated into liquid refrigerant and gas refrigerant by the gas-liquid separator (14). Among these, the gas refrigerant flows between the low-stage compression mechanism and the high-stage compression mechanism of the compressor (11) through the injection pipe (20). On the other hand, the liquid refrigerant flows into the indoor heat exchanger (16) after being reduced to a low pressure in the second expansion valve (15).

  In the indoor heat exchanger (16), the refrigerant absorbs heat from the indoor air and evaporates. As a result, the room air is cooled and supplied to the room. The low-pressure gas refrigerant evaporated in the indoor heat exchanger (16) is sucked into the compressor (11) and compressed again.

(Heating operation)
In the heating operation, as shown in FIG. 6, when the compressor (11) is started with the four-way valve (17) set to the second position, the refrigerant circuit (10) causes the indoor heat exchanger (16 ) Becomes a radiator, while a two-stage compression refrigeration cycle in which the outdoor heat exchanger (12) becomes an evaporator is performed.

  Specifically, when the compressor (11) is started, the high-pressure gas refrigerant compressed in the compressor (11) flows into the indoor heat exchanger (16) via the four-way valve (17). In the indoor heat exchanger (16), the high-pressure gas refrigerant exchanges heat with room air and dissipates heat to be cooled. As a result, the room air is heated and supplied to the room.

  The refrigerant cooled in the indoor heat exchanger (16) is depressurized to an intermediate pressure by the second expansion valve (15), and then separated into liquid refrigerant and gas refrigerant by the gas-liquid separator (14). Among these, the gas refrigerant flows between the low-stage compression mechanism and the high-stage compression mechanism of the compressor (11) through the injection pipe (20). On the other hand, the liquid refrigerant is reduced to a low pressure in the first expansion valve (13) and then flows into the outdoor heat exchanger (12).

  In the outdoor heat exchanger (12), the refrigerant absorbs heat from the outdoor air and evaporates. The low-pressure gas refrigerant evaporated in the outdoor heat exchanger (12) is sucked into the compressor (11) and compressed again.

(Control of suction volume ratio changing means)
In the first embodiment, when the operating condition of the air conditioner (1) changes, the suction volume ratio changing means (2) changes the suction volume ratio Vr. Specifically, the first three-way valve (18) and the second three-way valve (19) constituting the switching mechanism are switched to the first position or the second position according to a change in operating conditions by a controller (not shown). It is done. Thereby, the connection relation of the three compression mechanism parts (31, 32, 33) is switched, and the suction volume ratio Vr is changed.

  More specifically, when both the first three-way valve (18) and the second three-way valve (19) are switched to the second position, the lower stage of the three compression mechanisms (31, 32, 33) It will be in the 1st state where the 1st compression mechanism part (31) used as a compression mechanism and the 2nd compression mechanism part (32) are connected in series. On the other hand, when both the first three-way valve (18) and the second three-way valve (19) are switched to the first position, the first compression mechanism (31) and the second compression mechanism (32) are connected in parallel. This is the second state. Moreover, in this Embodiment 1, when switching to air_conditionaing | cooling operation, a 1st three-way valve (18) and a 2nd three-way valve (19) are switched to a 2nd position, and it will be in the said 1st state, and heating operation is carried out. At the time of switching, the first three-way valve (18) and the second three-way valve (19) are switched to the first position to be in the second state. Hereinafter, the relationship between each state and the suction volume ratio Vr will be described in detail.

  As shown in FIG. 5, in the first state, the first connecting pipe (26) and the second connecting pipe (27) communicate with each other, and the second connecting pipe (27) and the third connecting pipe (28). And communicate.

  Thus, the refrigerant in the low pressure state of the low pressure gas pipe (25) is first sucked into the first compression mechanism (31) and compressed in the first compression mechanism (31). The refrigerant compressed in the first compression mechanism section (31) passes through the first communication pipe (26), the second communication pipe (27), and the third communication pipe (28) to the second compression mechanism section (32). Inhaled and compressed in the second compression mechanism (32) until it reaches an intermediate pressure state.

  The refrigerant compressed to the intermediate pressure state in the second compression mechanism section (32) is sucked into the third compression mechanism section (33) through the fourth communication pipe (29), and the third compression mechanism section (33). And compressed to a high pressure state. In addition, the gas refrigerant separated from the liquid refrigerant in the gas-liquid separator (14) flows into the middle part of the fourth communication pipe (29) through the injection pipe (20). Therefore, the refrigerant flowing through the fourth connecting pipe (29) is cooled by the gas refrigerant flowing from the injection pipe (20) and then sucked into the third compression mechanism section (33).

  The refrigerant compressed to the high pressure state in the third compression mechanism section (33) is discharged into the internal space (S1) of the casing (40), and eventually the high pressure gas pipe (21 through the high pressure discharge pipe (56). ).

  Thus, in the first state, the first compression mechanism portion (31) and the second compression mechanism portion (32) are connected in series and used as the low-stage compression mechanism, while the third compression mechanism portion (33). Is used as a high-stage compression mechanism. Thereby, in the first state, the suction volume of the low-stage compression mechanism becomes the suction volume V1 of the first compression mechanism part (31), and the suction volume of the high-stage compression mechanism becomes the suction volume of the third compression mechanism part (33). The suction volume is V3. Therefore, the suction volume ratio Vr is V3 / V1.

  On the other hand, as shown in FIG. 6, in the second state, the first communication pipe (26) communicates with the fourth communication junction pipe (29a) connected to the middle part of the fourth communication pipe (29). At the same time, the low-pressure gas branch pipe (25a) connected to the middle portion of the low-pressure gas pipe (25) communicates with the third communication pipe (28).

  As a result, the low-pressure gas state refrigerant in the low-pressure gas pipe (25) is sucked into the first compression mechanism (31), and a part of the low-pressure gas is connected to the midway part of the low-pressure gas pipe (25). The air is sucked into the second compression mechanism section (32) through the branch pipe (25a) and the third communication pipe (28). Then, the first compression mechanism portion (31) and the second compression mechanism portion (32) are respectively compressed until they reach an intermediate pressure state.

  The refrigerant compressed to the intermediate pressure state in the first compression mechanism section (31) passes through the first communication pipe (26) and the fourth communication junction pipe (29a), and is in the middle of the fourth communication pipe (29). Flow into. On the other hand, the refrigerant compressed to the intermediate pressure state in the second compression mechanism part (32) flows into the fourth connecting pipe (29) and joins with the refrigerant flowing in from the fourth connecting joining pipe (29a). The air is sucked into the third compression mechanism part (33) and compressed in the third compression mechanism part (33) until a high pressure state is reached. The gas refrigerant separated from the liquid refrigerant in the gas-liquid separator (14) is disposed downstream of the fourth connecting pipe (29a) of the fourth connecting pipe (29) via the injection pipe (20). Inflow. Therefore, the refrigerant flowing through the fourth connecting pipe (29) is cooled by the gas refrigerant flowing from the injection pipe (20) and then sucked into the third compression mechanism section (33).

  The refrigerant compressed to the high pressure state in the third compression mechanism section (33) is discharged into the internal space (S1) of the casing (40), and eventually the high pressure gas pipe (21 through the high pressure discharge pipe (56). ).

  Thus, in the second state, the first compression mechanism portion (31) and the second compression mechanism portion (32) are connected in parallel and used as the low-stage compression mechanism, while the third compression mechanism portion (33). Is used as a high-stage compression mechanism. As a result, in the second state, the suction volume of the low-stage compression mechanism is the sum of the suction volume V1 of the first compression mechanism section (31) and the suction volume V2 of the second compression mechanism section (32). The suction volume of the compression mechanism is the suction volume V3 of the third compression mechanism section (33). Therefore, the suction volume ratio Vr is V3 / (V1 + V2).

  Here, in the compressor (11) of the air conditioner (1), three compression mechanism parts (31, 32, 33) are connected to one drive shaft (35). Thereby, for example, when the suction volume ratio Vr is set to a suitable value in the cooling operation and the heating operation is performed without changing the suction volume ratio Vr, the value of the intermediate pressure is intermediate between the low pressure and the high pressure in the heating operation. On the other hand, when the suction volume ratio Vr is set to a suitable value in the heating operation and the cooling operation is performed without changing the suction volume ratio Vr, the value of the intermediate pressure between the low pressure and the high pressure is set in the cooling operation. Higher than the middle. Therefore, if the suction volume ratio Vr is set so that the intermediate pressure becomes an average value between the low pressure and the high pressure in one of the operating conditions, the intermediate pressure greatly deviates from the average value of the low pressure and the high pressure in the other operating condition. Will end up.

  However, in the present air conditioner (1), as described above, when switching to the cooling operation, the suction volume ratio Vr is changed by the suction volume ratio changing means (2). Thereby, since the compression ratio in the low-stage side compression mechanism becomes small, the intermediate pressure is lowered and becomes a value close to the average value of the low pressure and the high pressure. As a result, a high COP can be obtained in the cooling operation. Further, since the intermediate pressure is reduced, the amount of gas injection from the injection pipe (20) as the cooling means becomes relatively large. Thereby, since the refrigerant | coolant between a low stage side compression mechanism and a high stage side compression mechanism is cooled more, the input of a compressor (11) can be reduced.

  On the other hand, in the present air conditioner (1), when switching to the heating operation, the suction volume ratio Vr is changed by the suction volume ratio changing means (2) so as to be reduced. As a result, the compression ratio in the low-stage side compression mechanism increases, so that the intermediate pressure rises and becomes a value close to the average value of the low pressure and the high pressure. As a result, a high COP can be obtained in the heating operation. In addition, as the intermediate pressure increases, the amount of gas injection from the injection pipe (20) as the cooling means becomes relatively small. As a result, the temperature of the refrigerant sucked into the high-stage compression mechanism is prevented from being reduced as much as possible, and the amount of heat absorbed from the outdoor air can be increased by increasing the refrigerant flow rate of the outdoor heat exchanger (12). Therefore, both reduction of the input of the compressor (11) and improvement of the heating capacity can be achieved.

  From the above, when the first three-way valve (18) and the second three-way valve (19) constituting the switching mechanism of the suction volume ratio changing means (2) are switched from the first state to the second state, the suction volume ratio While Vr decreases, the suction volume ratio Vr increases when the second state is switched to the first state.

-Effect of Embodiment 1-
As described above, according to the air conditioner (1), since the suction volume ratio changing means (2) is provided, a high COP can be obtained by changing the suction volume ratio Vr in accordance with a change in operating conditions. Thus, the intermediate pressure can be varied (increased or decreased). Therefore, a high COP can be obtained regardless of changes in operating conditions.

  Moreover, according to this air conditioning apparatus (1), since three compression mechanism parts are provided, the three compression mechanism parts (31, 32, 33) can be obtained without changing the shape of the cylinder chamber of the compression mechanism part. By changing the connection relationship, the suction volume ratio Vr can be easily changed.

  Further, according to the air conditioner (1), the first three-way valve (18) and the second three-way valve (19) constituting the switching mechanism of the suction volume ratio changing means (2) serve as a low-stage compression mechanism. The suction volume ratio Vr can be easily changed by switching the connection relationship between the first compression mechanism section (31) and the second compression mechanism section (32) used in series or in parallel.

  Furthermore, in the refrigerant circuit (10) of the air conditioner (1), carbon dioxide is used as the refrigerant. Thus, in the two-stage compression refrigeration cycle using carbon dioxide as a refrigerant, there is a problem that heat dissipation loss is large and it is difficult to obtain a high coefficient of performance (COP). Therefore, the significance of improving the COP by providing the suction volume ratio changing means (2) is further increased.

<< Embodiment 2 of the Invention >>
The air conditioner (1) of Embodiment 2 shown in FIGS. 7 and 8 will be described. Hereinafter, differences from the first embodiment will be described.

-Overall configuration-
In the second embodiment, the suction volume ratio changing means (2) is a first state in which the second compression mechanism part (32) and the third compression mechanism part (33) used as the high-stage side compression mechanism are connected in parallel. And a switching mechanism for switching to a second state connected in series. The switching mechanism includes a third three-way valve (90) and a fourth three-way valve (91). The third three-way valve (90) and the fourth three-way valve (91) have first to third ports (P1, P2, P3), respectively, and the first port (P1) and the second port (P2) communicate with each other. The first position is switched to the second position where the second port (P2) and the third port (P3) communicate with each other.

  Also in Embodiment 2, the high-pressure discharge pipe (56) is connected to the first port (P1) of the four-way valve (17) via the high-pressure gas pipe (21). One end of the low pressure gas pipe (25) is connected to the third port (P3) of the four-way valve (17). The other end of the low pressure gas pipe (25) is connected to the first suction pipe (51).

  One end of the first connecting pipe (26) is connected to the first discharge pipe (52), and the other end of the first connecting pipe (26) is connected to the second suction pipe (53). One end of the first connecting branch pipe (26a) is connected to the middle part of the first connecting pipe (26), and the other end of the first connecting branch pipe (26a) is connected to the second three-way valve (19). Connected to the first port (P1). One end is connected to the gas-liquid separator (14) on the first discharge pipe (52) side of the connection part of the first connection branch pipe (26a) in the middle of the first connection pipe (26). The other end of the injection pipe (20) is connected. The injection pipe (20) cools the refrigerant being compressed by joining the gas refrigerant separated by the gas-liquid separator (14) with the refrigerant being compressed in the compressor (11). The cooling means is configured.

  One end of the second communication pipe (27) is connected to the second discharge pipe (54), and the other end of the second communication pipe (27) is connected to the second port (P2 of the third three-way valve (90)). )It is connected to the. One end of a high pressure gas junction pipe (21a) is connected to the first port (P1) of the third three-way valve (90), and the other end of the high pressure gas junction pipe (21a) is connected to the high pressure gas pipe (21). It is connected to the middle part. Further, one end of the third communication pipe (28) is connected to the third port (P3) of the third three-way valve (90), and the other end of the third communication pipe (28) is connected to the fourth three-way valve (91). ) To the third port (P3). One end of a fourth connecting pipe (29) is connected to the second port (P2) of the fourth three-way valve (91), and the other end of the fourth connecting pipe (29) is connected to the third suction pipe (55). It is connected.

  Since other configurations are the same as those of the first embodiment, description thereof is omitted.

-Driving action-
Next, the operation of the air conditioner (1) will be described. Also in the second embodiment, the air conditioner (1) can be switched between a cooling operation (see FIG. 7) and a heating operation (see FIG. 8). In addition, since it is the same as that of Embodiment 1 about air_conditionaing | cooling operation operation and heating operation operation, description is abbreviate | omitted.

(Control of suction volume ratio changing means)
Also in the second embodiment, when the operating condition of the air conditioner (1) changes, the suction volume ratio Vr is changed by the suction volume ratio changing means (2). Specifically, the third three-way valve (90) and the fourth three-way valve (91) constituting the switching mechanism are switched to the first position or the second position according to a change in operating conditions by a controller (not shown). It is done. Thereby, the connection relation of the three compression mechanism parts (31, 32, 33) is switched, and the suction volume ratio Vr is changed.

  More specifically, when both the third three-way valve (90) and the fourth three-way valve (91) are switched to the first position, the higher stage of the three compression mechanisms (31, 32, 33) It will be in the 1st state where the 2nd compression mechanism part (32) used as a compression mechanism and the 3rd compression mechanism part (33) are connected in parallel. On the other hand, when both the third three-way valve (90) and the fourth three-way valve (91) are switched to the second position, the second compression mechanism part (32) and the third compression mechanism part (33) are connected in series. This is the second state. In the second embodiment, when switching to the cooling operation, the third three-way valve (90) and the fourth three-way valve (91) are switched to the first position to be in the first state and switched to the heating operation. In this case, the third three-way valve (90) and the fourth three-way valve (91) are switched to the second position to be in the second state. Hereinafter, the relationship between each state and the suction volume ratio Vr will be described in detail.

  As shown in FIG. 7, in the first state, the first connecting branch pipe (26a) and the fourth connecting pipe (29) communicate with each other, and the second connecting pipe (27) and the high-pressure gas junction pipe (21a ).

  As a result, the refrigerant in the low pressure state of the low pressure gas pipe (25) is first sucked into the first compression mechanism (31) and compressed in the first compression mechanism (31) until it reaches an intermediate pressure state.

  The refrigerant compressed to the intermediate pressure state in the first compression mechanism part (31) is sucked into the second compression mechanism part (32) through the first communication pipe (26), and a part thereof is the first. The air is sucked into the third compression mechanism (33) through the first connecting branch pipe (26a) and the fourth connecting pipe (29) connected to the middle part of the one connecting pipe (26). The gas refrigerant separated from the liquid refrigerant in the gas-liquid separator (14) is disposed upstream of the first communication branch pipe (26a) of the first communication pipe (26) via the injection pipe (20). Inflow. Therefore, the refrigerant flowing through the first communication pipe (26) is sucked into the third compression mechanism section (33) after being cooled by the gas refrigerant flowing from the injection pipe (20).

  The refrigerant sucked into the second compression mechanism part (32) and the third compression mechanism part (33) is in a high pressure state in the second compression mechanism part (32) and the third compression mechanism part (33), respectively. Compressed. And the refrigerant | coolant of a 2nd compression mechanism part (32) flows in into the middle part of a high pressure gas pipe (21) through a 2nd connecting pipe (27) and a high pressure gas confluence | merging pipe (21a). On the other hand, the refrigerant in the third compression mechanism (33) is discharged into the internal space (S1) of the casing (40) and eventually flows into the high-pressure gas pipe (21) via the high-pressure discharge pipe (56).

  Thus, in the first state, the first compression mechanism (31) is used as the low-stage compression mechanism, while the second compression mechanism (32) and the third compression mechanism (33) are connected in parallel. Used as a high-stage compression mechanism. As a result, in the first state, the suction volume of the low-stage compression mechanism is the suction volume V1 of the first compression mechanism section (31), and the suction volume of the high-stage compression mechanism is that of the second compression mechanism section (32). This is the sum of the suction volume V2 and the suction volume V3 of the third compression mechanism (33). Therefore, the suction volume ratio Vr is (V2 + V3) / V1.

  On the other hand, as shown in FIG. 8, in the second state, the second communication pipe (27) and the third communication pipe (28) communicate with each other, and the third communication pipe (28) and the fourth communication pipe ( 29) communicates.

  As a result, the refrigerant in the low pressure state of the low pressure gas pipe (25) is first sucked into the first compression mechanism (31) and compressed in the first compression mechanism (31) until it reaches an intermediate pressure state.

  The refrigerant compressed to the intermediate pressure state in the first compression mechanism section (31) is sucked into the second compression mechanism section (32) through the first connecting pipe (26), and the second compression mechanism section ( 32) is compressed. The gas refrigerant separated from the liquid refrigerant in the gas-liquid separator (14) flows into the middle part of the first communication pipe (26) through the injection pipe (20). Therefore, the refrigerant flowing through the first communication pipe (26) is sucked into the second compression mechanism section (32) after being cooled by the gas refrigerant flowing in from the injection pipe (20).

  The refrigerant compressed in the second compression mechanism section (32) passes through the second communication pipe (27), the third communication pipe (28), and the fourth communication pipe (29) to the third compression mechanism section (33). Inhaled and compressed in the third compression mechanism (33) until it reaches a high pressure state.

  The refrigerant compressed to the high pressure state in the third compression mechanism section (33) is discharged into the internal space (S1) of the casing (40), and eventually the high pressure gas pipe (21 through the high pressure discharge pipe (56). ).

  Thus, in the second state, the first compression mechanism (31) is used as the low-stage compression mechanism, while the second compression mechanism (32) and the third compression mechanism (33) are connected in series. Used as a high-stage compression mechanism. Thereby, in the second state, the suction volume of the low-stage compression mechanism becomes the suction volume V1 of the first compression mechanism section (31), and the suction volume of the high-stage compression mechanism becomes the suction volume of the second compression mechanism section (32). The suction volume V2. Therefore, the suction volume ratio Vr is V2 / V1.

  From the above, when the third three-way valve (90) and the fourth three-way valve (91) constituting the switching mechanism of the suction volume ratio changing means (2) are switched from the first state to the second state, the suction volume ratio While Vr decreases, the suction volume ratio Vr increases when the second state is switched to the first state.

-Effect of Embodiment 2-
As described above, also in the air conditioner (1) of the second embodiment, the third three-way valve (90) and the fourth three-way valve (91) constituting the switching mechanism of the suction volume ratio changing means (2) The suction volume ratio Vr can be easily changed by switching the connection relationship between the second compression mechanism section (32) and the third compression mechanism section (33) used as the compression mechanism in series or in parallel.

<< Embodiment 3 of the Invention >>
The air conditioner (1) of Embodiment 2 shown in FIGS. 9 and 10 will be described. Hereinafter, differences from the first embodiment will be described.

-Overall configuration-
In the third embodiment, the third compression mechanism (33) is configured in substantially the same manner as the second compression mechanism (32) in the first embodiment. Specifically, the discharge space and discharge port of the third compression mechanism (33) formed in the front head (37f) in the first embodiment are formed in the third cylinder (81) (not shown). A discharge valve is attached to the discharge port, and a third discharge pipe (57) is connected to the discharge space.

  The said 3rd discharge pipe (57) is provided so that the inside and outside of a casing (40) may penetrate like a 1st discharge pipe (52) and a 2nd discharge pipe (54). The third discharge pipe (57) is provided above the second discharge pipe (54). Further, a high-pressure connecting pipe (58) is provided above the third discharge pipe (57) so as to penetrate the inside and outside of the casing (40). The high-pressure connecting pipe (58) is provided such that an inner end opens between the electric motor (34) and the three compression mechanism parts (31, 32, 33).

  In the third embodiment, the suction volume ratio changing means (2) includes the first compression mechanism part (31) and the second compression mechanism part having different suction volumes among the three compression mechanism parts (31, 32, 33). (32) A switching mechanism for changing the connection relationship is provided. The switching mechanism includes a second four-way valve (92) and a third four-way valve (93). The second four-way valve (92) and the third four-way valve (93) have first to fourth ports (P1, P2, P3, P4), respectively, and the first port (P1) and the second port (P2) Can be switched to a first position at which the third port (P3) and the fourth port (P4) communicate with each other.

  Also in Embodiment 3, the high-pressure discharge pipe (56) is connected to the first port (P1) of the four-way valve (17) via the high-pressure gas pipe (21). One end of the low pressure gas pipe (25) is connected to the third port (P3) of the four-way valve (17). The other end of the low pressure gas pipe (25) is connected to the third suction pipe (55). One end of the low-pressure gas branch pipe (25a) is connected to the middle portion of the low-pressure gas pipe (25), and the other end of the low-pressure gas branch pipe (25a) is the first port of the third four-way valve (93). Connected to (P1).

  One end of the first communication pipe (26) is connected to the fourth port (P4) of the third four-way valve (93), and the other end of the first communication pipe (26) is connected to the first suction pipe (51). It is connected to the. One end of the second communication pipe (27) is connected to the second port (P2) of the third four-way valve (93), and the other end of the second communication pipe (27) is connected to the second suction pipe ( 53) is connected.

  One end of a third connecting pipe (28) is connected to the first discharge pipe (52), and the other end of the third connecting pipe (28) is connected to the third port (P3) of the second four-way valve (92). It is connected to the. The second discharge pipe (54) is connected to one end of a fourth communication pipe (29), and the other end of the fourth communication pipe (29) is connected to the first port (92) of the second four-way valve (92). Connected to P1). Further, one end of a fifth communication pipe (30) is connected to the third discharge pipe (57), and the other end of the fifth communication pipe (30) is connected to the third port (93) of the third four-way valve (93). Connected to P3).

  One end of a fifth connecting / merging pipe (30a) is connected to the middle part of the fifth connecting pipe (30), and the other end of the fifth connecting / merging pipe (30a) is connected to the second four-way valve (92). It is connected to the second port (P2). One end is connected to the gas-liquid separator (14) on the third four-way valve (93) side of the middle of the fifth connecting pipe (30) from the connecting part of the fifth connecting junction pipe (30a). The other end of the injection pipe (20) is connected. The injection pipe (20) cools the refrigerant being compressed by joining the gas refrigerant separated by the gas-liquid separator (14) with the refrigerant being compressed in the compressor (11). The cooling means is configured.

  One end of a sixth connecting pipe (59) is connected to the fourth port (P4) of the second four-way valve (92), and the other end of the sixth connecting pipe (59) is connected to the high pressure connecting pipe (58). It is connected.

  Since other configurations are the same as those of the first embodiment, description thereof is omitted.

-Driving action-
Next, the operation of the air conditioner (1) will be described. Also in Embodiment 3, the air conditioner (1) can be switched between a cooling operation (see FIG. 9) and a heating operation (see FIG. 10). In addition, since it is the same as that of Embodiment 1 about air_conditionaing | cooling operation operation and heating operation operation, description is abbreviate | omitted.

(Control of suction volume ratio changing means)
Also in the third embodiment, when the operating condition of the air conditioner (1) changes, the suction volume ratio Vr is changed by the suction volume ratio changing means (2). Specifically, the second four-way valve (92) and the third four-way valve (93) constituting the switching mechanism are switched to the first position or the second position according to a change in operating conditions by a controller (not shown). It is done. Thereby, the connection relation of the three compression mechanism parts (31, 32, 33) is switched, and the suction volume ratio Vr is changed.

  Specifically, when both the second four-way valve (92) and the third four-way valve (93) are switched to the first position, the second compression mechanism portion (32) and the third compression mechanism portion (33) are arranged in parallel. The first compression mechanism section (31) is in a first state used as a high-stage compression mechanism, while being used as a low-stage compression mechanism. On the other hand, when the second four-way valve (92) and the third four-way valve (93) are switched to the second position, the first compression mechanism (31) and the third compression mechanism (33) are connected in parallel. While being used as a low-stage compression mechanism, the second compression mechanism section (32) is in a second state used as a high-stage compression mechanism. That is, the connection relationship between the first compression mechanism (31) and the second compression mechanism (32) is switched between the first state and the second state.

  In the third embodiment, when switching to the cooling operation, the second four-way valve (92) and the third four-way valve (93) are switched to the first position to be in the first state, and switched to the heating operation. In this case, the second four-way valve (92) and the third four-way valve (93) are switched to the second position to be in the second state. Hereinafter, the relationship between each state and the suction volume ratio Vr will be described in detail.

  As shown in FIG. 9, in the first state, the low pressure gas branch pipe (25a) and the second connecting pipe (27) communicate with each other, and the fifth connecting pipe (30) and the first connecting pipe (26) Are communicated, the fourth communication pipe (29) and the fifth communication junction pipe (30a) are communicated, and the third communication pipe (28) and the sixth communication pipe (59) are communicated.

  Thus, the low-pressure gas state refrigerant in the low-pressure gas pipe (25) is sucked into the third compression mechanism part (33), and a part of the low-pressure gas is connected to the middle part of the low-pressure gas pipe (25). The air is sucked into the second compression mechanism (32) through the branch pipe (25a) and the second communication pipe (27). Then, the second compression mechanism section (32) and the third compression mechanism section (33) are respectively compressed until they reach an intermediate pressure state.

  The refrigerant compressed to the intermediate pressure state in the second compression mechanism section (32) passes through the fourth connecting pipe (29) and the fifth connecting junction pipe (30a), and the middle section of the fifth connecting pipe (30). Flow into. On the other hand, the refrigerant compressed to the intermediate pressure state in the third compression mechanism section (33) flows into the fifth communication pipe (30) and merges with the refrigerant flowing in from the fifth communication junction pipe (30a). The combined refrigerant is sucked into the first compression mechanism part (31) through the first communication pipe (26), and is compressed in the first compression mechanism part (31) until a high pressure state is reached. The gas refrigerant separated from the liquid refrigerant in the gas-liquid separator (14) is disposed downstream of the fifth connecting pipe (30a) of the fifth connecting pipe (30) via the injection pipe (20). Inflow. Therefore, the refrigerant flowing through the fifth communication pipe (30) is cooled by the gas refrigerant flowing from the injection pipe (20) and then sucked into the first compression mechanism section (31).

  The refrigerant compressed to the high pressure state in the first compression mechanism (31) enters the internal space (S1) of the casing (40) through the third connecting pipe (28) and the sixth connecting pipe (59). It is discharged and eventually flows into the high-pressure gas pipe (21) through the high-pressure discharge pipe (56).

  Thus, in the first state, the second compression mechanism part (32) and the third compression mechanism part (33) are connected in parallel and used as the low-stage compression mechanism, while the first compression mechanism part (31) Is used as a high-stage compression mechanism. As a result, in the first state, the suction volume of the low-stage compression mechanism is the sum of the suction volume V2 of the second compression mechanism section (32) and the suction volume V3 of the third compression mechanism section (33). The suction volume of the compression mechanism is the suction volume V1 of the first compression mechanism section (31). Therefore, the suction volume ratio Vr is V1 / (V2 + V3).

  On the other hand, as shown in FIG. 10, in the second state, the low pressure gas branch pipe (25a) communicates with the first communication pipe (26), and the fifth communication pipe (30) and the second communication pipe (27 ) Communicate with each other, the fourth communication pipe (29) and the sixth communication pipe (59) communicate with each other, and the third communication pipe (28) and the fifth communication junction pipe (30a) communicate with each other.

  Thus, the low-pressure gas state refrigerant in the low-pressure gas pipe (25) is sucked into the third compression mechanism part (33), and a part of the low-pressure gas is connected to the middle part of the low-pressure gas pipe (25). The air is sucked into the first compression mechanism (31) through the branch pipe (25a) and the first communication pipe (26). Then, the first compression mechanism portion (31) and the third compression mechanism portion (33) are respectively compressed until they reach an intermediate pressure state.

  The refrigerant compressed to the intermediate pressure state in the first compression mechanism section (31) passes through the third connecting pipe (28) and the fifth connecting junction pipe (30a), and is in the middle of the fifth connecting pipe (30). Flow into. On the other hand, the refrigerant compressed to the intermediate pressure state in the third compression mechanism section (33) flows into the fifth communication pipe (30) and merges with the refrigerant flowing in from the fifth communication junction pipe (30a). The merged refrigerant is sucked into the second compression mechanism part (32) through the second communication pipe (27) and compressed in the second compression mechanism part (32) until a high pressure state is reached. The gas refrigerant separated from the liquid refrigerant in the gas-liquid separator (14) is disposed downstream of the fifth connecting pipe (30a) of the fifth connecting pipe (30) via the injection pipe (20). Inflow. Therefore, the refrigerant flowing through the fifth communication pipe (30) is cooled by the gas refrigerant flowing from the injection pipe (20) and then sucked into the second compression mechanism section (32).

  The refrigerant compressed to the high pressure state in the second compression mechanism (32) enters the internal space (S1) of the casing (40) through the fourth connecting pipe (29) and the sixth connecting pipe (59). It is discharged and eventually flows into the high-pressure gas pipe (21) through the high-pressure discharge pipe (56).

  Thus, in the second state, the first compression mechanism portion (31) and the third compression mechanism portion (33) are connected in parallel and used as the low-stage compression mechanism, while the second compression mechanism portion (32) Is used as a high-stage compression mechanism. As a result, in the second state, the suction volume of the low-stage compression mechanism is the sum of the suction volume V1 of the first compression mechanism section (31) and the suction volume V3 of the third compression mechanism section (33). The suction volume of the compression mechanism is the suction volume V2 of the second compression mechanism section (32). Therefore, the suction volume ratio Vr is V2 / (V1 + V3).

  As described above, when the second four-way valve (92) and the third four-way valve (93) constituting the switching mechanism of the suction volume ratio changing means (2) are switched from the first state to the second state, the suction volume ratio is changed. While Vr decreases, the suction volume ratio Vr increases when the second state is switched to the first state.

-Effect of Embodiment 3-
As described above, also in the air conditioner (1) of the third embodiment, the suction volume can be reduced by the second four-way valve (92) and the third four-way valve (93) constituting the switching mechanism of the suction volume ratio changing means (2). The suction volume ratio Vr can be easily changed by changing the connection relationship between the two different compression mechanisms (31, 32).

<< Embodiment 4 of the Invention >>
The air conditioner (1) of Embodiment 2 shown in FIGS. 11 and 12 will be described. Hereinafter, differences from the first embodiment will be described.

-Overall configuration-
In the fourth embodiment, the suction volume ratio changing means (2) includes the first state in which the refrigerant is compressed in all the compression mechanism portions of the three compression mechanism portions (31, 32, 33), and the three compression mechanism portions. The refrigerant is compressed in the two compression mechanism portions (31, 33) of (31, 32, 33), while the refrigerant passes through the remaining one compression mechanism portion (32) without being compressed. A switching mechanism for switching between the two states.

  Specifically, the switching mechanism is constituted by a fifth three-way valve (94). The fifth three-way valve (94) includes first to third ports (P1, P2, P3), a first position where the first port (P1) and the second port (P2) communicate with each other, The port (P2) and the third port (P3) can be switched to a second position where they communicate.

  Also in Embodiment 4, the high-pressure discharge pipe (56) is connected to the first port (P1) of the four-way valve (17) via the high-pressure gas pipe (21). One end of the low pressure gas pipe (25) is connected to the third port (P3) of the four-way valve (17). The other end of the low pressure gas pipe (25) is connected to the first suction pipe (51).

  One end of the first connecting pipe (26) is connected to the first discharge pipe (52), and the other end of the first connecting pipe (26) is connected to the second suction pipe (53). One end of the first connecting junction pipe (26a) is connected to the middle part of the first connecting pipe (26), and the other end of the first connecting branch pipe (26a) is connected to the fifth three-way valve (94). It is connected to the third port (P3). In addition, one end of the first connection branch pipe (26b) is connected to the second suction pipe (53) side of the connection part of the first connection junction pipe (26a) in the middle of the first connection pipe (26). The other end of the first connecting branch pipe (26b) is connected to the third suction pipe (55). Further, one end of the first connecting pipe (26) is connected between the connecting portion of the first connecting junction pipe (26a) and the connecting portion of the first connecting branch pipe (26b). ) Is connected to the other end of the injection pipe (20). The injection pipe (20) cools the refrigerant being compressed by joining the gas refrigerant separated by the gas-liquid separator (14) with the refrigerant being compressed in the compressor (11). The cooling means is configured.

  One end of a second connecting pipe (27) is connected to the second discharge pipe (54), and the other end of the second connecting pipe (27) is connected to the second port (P2 of the fifth three-way valve (94). )It is connected to the. One end of a high pressure gas junction pipe (21a) is connected to the first port (P1) of the fifth three-way valve (94), and the other end of the high pressure gas junction pipe (21a) is connected to the high pressure gas pipe (21). It is connected to the middle part.

  Since other configurations are the same as those of the first embodiment, description thereof is omitted.

-Driving action-
Next, the operation of the air conditioner (1) will be described. Also in Embodiment 4, the air conditioner (1) can be switched between a cooling operation (see FIG. 11) and a heating operation (see FIG. 12). In addition, since it is the same as that of Embodiment 1 about air_conditionaing | cooling operation operation and heating operation operation, description is abbreviate | omitted.

(Control of suction volume ratio changing means)
Also in the fourth embodiment, when the operating condition of the air conditioner (1) changes, the suction volume ratio Vr is changed by the suction volume ratio changing means (2). Specifically, when the operating condition changes, the controller (not shown) switches the fifth three-way valve (94) constituting the switching mechanism to the first position or the second position, and the suction volume ratio Vr is changed.

  More specifically, when the fifth three-way valve (94) is switched to the first position, the refrigerant is compressed in all the compression mechanism portions of the three compression mechanism portions (31, 32, 33). It becomes a state. On the other hand, when the fifth three-way valve (94) is switched to the second position, the suction side and the discharge side of the second compression mechanism section (32) become substantially equal in pressure, and the refrigerant is compressed in the second compression state. While passing through the mechanism portion (32) without compression, the first compression mechanism portion (31) and the third compression mechanism portion (33) are in the second state in which the refrigerant is compressed. In the fourth embodiment, the fifth three-way valve (94) is switched to the first position when switched to the cooling operation to be in the first state, and the fifth three-way valve is switched to the heating operation. (94) is switched to the second position to enter the second state. Hereinafter, the relationship between each state and the suction volume ratio Vr will be described in detail.

  As shown in FIG. 11, in the first state, the second communication pipe (27) and the high-pressure gas junction pipe (21a) communicate with each other.

  As a result, the refrigerant in the low pressure state of the low pressure gas pipe (25) is first sucked into the first compression mechanism (31) and compressed in the first compression mechanism (31) until it reaches an intermediate pressure state.

  The refrigerant compressed to the intermediate pressure state in the first compression mechanism part (31) is sucked into the second compression mechanism part (32) through the first communication pipe (26), and a part thereof is the first. The air is sucked into the third compression mechanism part (33) through the first connection branch pipe (26b) connected to the middle part of the one connection pipe (26). The gas refrigerant separated from the liquid refrigerant in the gas-liquid separator (14) is disposed upstream of the first communication branch pipe (26b) of the first communication pipe (26) via the injection pipe (20). Inflow. Therefore, the refrigerant flowing through the first communication pipe (26) is sucked into the second compression mechanism part (32) and the third compression mechanism part (33) after being cooled by the gas refrigerant flowing in from the injection pipe (20). The

  The refrigerant sucked into the second compression mechanism part (32) and the third compression mechanism part (33) is in a high pressure state in the second compression mechanism part (32) and the third compression mechanism part (33), respectively. Compressed. And the refrigerant | coolant of a 2nd compression mechanism part (32) flows in into the middle part of a high pressure gas pipe (21) through a 2nd connecting pipe (27) and a high pressure gas confluence | merging pipe (21a). On the other hand, the refrigerant in the third compression mechanism (33) is discharged into the internal space (S1) of the casing (40) and eventually flows into the high-pressure gas pipe (21) via the high-pressure discharge pipe (56).

  Thus, in the first state, the first compression mechanism (31) is used as the low-stage compression mechanism, while the second compression mechanism (32) and the third compression mechanism (33) are connected in parallel. Used as a high-stage compression mechanism. As a result, in the first state, the suction volume of the low-stage compression mechanism is the suction volume V1 of the first compression mechanism section (31), and the suction volume of the high-stage compression mechanism is that of the second compression mechanism section (32). This is the sum of the suction volume V2 and the suction volume V3 of the third compression mechanism (33). Therefore, the suction volume ratio Vr is (V2 + V3) / V1.

  On the other hand, as shown in FIG. 12, in the second state, the second communication pipe (27) and the first communication junction pipe (26a) communicate with each other. As described above, the first connecting / merging pipe (26a) is connected to the first connecting pipe (26), and the first connecting pipe (26) is connected to the second suction pipe (53). The second communication pipe (27) is connected to the second discharge pipe (54). Therefore, in the second state, the suction side and the discharge side of the second compression mechanism section (32) communicate with each other and are in a substantially equal pressure state. Therefore, the refrigerant flows in the three compression mechanisms (31, 32, 33) are as follows.

  The refrigerant in the low-pressure state of the low-pressure gas pipe (25) is first sucked into the first compression mechanism (31) and compressed in the first compression mechanism (31) until it reaches an intermediate pressure state.

  The refrigerant compressed to the intermediate pressure state in the first compression mechanism part (31) flows into the second compression mechanism part (32) through the first connecting pipe (26), and a part thereof is the first. The air is sucked into the third compression mechanism part (33) through the first connection branch pipe (26b) connected to the middle part of the communication pipe (26). The gas refrigerant separated from the liquid refrigerant in the gas-liquid separator (14) is disposed upstream of the first communication branch pipe (26b) of the first communication pipe (26) via the injection pipe (20). Inflow. Therefore, the refrigerant flowing through the first communication pipe (26) is cooled by the gas refrigerant flowing from the injection pipe (20), and then flows into the second compression mechanism section (32) and the third compression mechanism section (33). Inhaled.

  The refrigerant flowing into the second compression mechanism part (32) passes through the inside of the second compression mechanism part (32) without being compressed in the second compression mechanism part (32), and the second communication pipe (27). And it flows into the middle part of the 1st connecting pipe (26) through the 1st connecting pipe (26a).

  On the other hand, the refrigerant sucked into the third compression mechanism part (33) is compressed in the third compression mechanism part (33) until it reaches a high pressure state. And the refrigerant | coolant compressed until it became a high pressure state in the 3rd compression mechanism part (33) is discharged by the internal space (S1) of a casing (40), and a high pressure gas pipe is finally passed through a high pressure discharge pipe (56). Flows into (21).

  Thus, in the second state, the first compression mechanism (31) is used as the low-stage compression mechanism and the third compression mechanism (33) is used as the high-stage compression mechanism, while the second compression mechanism. The part (32) is not used as any compression mechanism. Thus, in the second state, the suction volume of the low-stage compression mechanism becomes the suction volume V1 of the first compression mechanism part (31), and the suction volume of the high-stage compression mechanism becomes the suction volume of the third compression mechanism part (33). The suction volume is V3. Therefore, the suction volume ratio Vr is V3 / V1.

  As described above, the suction volume ratio Vr becomes smaller when the fifth state is switched from the first state to the second state by the fifth three-way valve (94) constituting the switching mechanism of the suction volume ratio changing means (2). When the state is switched from the first state to the first state, the suction volume ratio Vr increases.

-Effect of Embodiment 4-
As described above, also in the air conditioner (1) of the fourth embodiment, the three compression mechanism parts (31, 32, 33) are provided by the fifth three-way valve (94) constituting the switching mechanism of the suction volume ratio changing means (2). ) In the first state where the refrigerant is compressed in all the compression mechanism parts and in two compression mechanism parts (31, 33) of the three compression mechanism parts (31, 32, 33), the refrigerant is compressed. On the other hand, the suction volume ratio Vr can be easily changed by switching between the second state in which the refrigerant passes without being compressed in the remaining one compression mechanism (32).

<< Embodiment 5 of the Invention >>
The air conditioner (1) of Embodiment 5 shown in FIGS. 13 and 14 will be described. Hereinafter, differences from the first embodiment will be described.

-Overall configuration-
In the fifth embodiment, the third compression mechanism (33) is configured in substantially the same manner as the second compression mechanism (32) in the first embodiment. Specifically, the discharge space and discharge port of the third compression mechanism (33) formed in the front head (37f) in the first embodiment are formed in the third cylinder (81) (not shown). A discharge valve is attached to the discharge port, and a third discharge pipe (57) is connected to the discharge space.

  The said 3rd discharge pipe (57) is provided so that the inside and outside of a casing (40) may penetrate like a 1st discharge pipe (52) and a 2nd discharge pipe (54). The third discharge pipe (57) is provided above the second discharge pipe (54). Further, a high-pressure connecting pipe (58) is provided above the third discharge pipe (57) so as to penetrate the inside and outside of the casing (40). The high-pressure connecting pipe (58) is provided such that an inner end opens between the electric motor (34) and the three compression mechanism parts (31, 32, 33).

  In the fifth embodiment, the suction volume ratio changing means (2) includes the first state in which the refrigerant is compressed in all the compression mechanism portions of the three compression mechanism portions (31, 32, 33) and the three compression modes. The refrigerant is compressed in the two compression mechanism parts (31, 32) of the mechanism parts (31, 32, 33), while the refrigerant passes through the remaining one compression mechanism part (33) without being compressed. A switching mechanism for switching to the second state is provided.

  Specifically, the switching mechanism is constituted by a sixth three-way valve (95). The sixth three-way valve (95) includes first to third ports (P1, P2, P3), a first position where the first port (P1) and the second port (P2) communicate with each other, The port (P2) and the third port (P3) can be switched to a second position where they communicate.

  Also in Embodiment 5, the high-pressure discharge pipe (56) is connected to the first port (P1) of the four-way valve (17) via the high-pressure gas pipe (21). One end of the low pressure gas pipe (25) is connected to the third port (P3) of the four-way valve (17). The other end of the low pressure gas pipe (25) is connected to the first suction pipe (51). One end of the low-pressure gas branch pipe (25a) is connected to the middle part of the low-pressure gas pipe (25), and the other end of the low-pressure gas branch pipe (25a) is the third port of the sixth three-way valve (95). (P3) connected.

  One end of the first connecting pipe (26) is connected to the first discharge pipe (52), and the other end of the first connecting pipe (26) is connected to the second suction pipe (53). One end of the first connecting / merging pipe (26a) is connected to the middle part of the first connecting pipe (26), and the other end of the first connecting / merging pipe (26a) is connected to the third discharge pipe (57). Has been. Further, one end of the first connection branch pipe (26b) is connected to the second suction pipe (53) side of the connection portion of the first connection pipe (26) of the first connection junction pipe (26a). The other end of the one connecting branch pipe (26b) is connected to the first port (P1) of the sixth three-way valve (95). Further, one end of the first connecting pipe (26) is connected between the connecting portion of the first connecting junction pipe (26a) and the connecting portion of the first connecting branch pipe (26b). ) Is connected to the other end of the injection pipe (20). The injection pipe (20) cools the refrigerant being compressed by joining the gas refrigerant separated by the gas-liquid separator (14) with the refrigerant being compressed in the compressor (11). The cooling means is configured.

  One end of the second communication pipe (27) is connected to the second port (P2) of the sixth three-way valve (95), and the other end of the second communication pipe (27) is connected to the third suction pipe (55). It is connected. Further, one end of a third communication pipe (28) is connected to the second discharge pipe (54), and the other end of the third communication pipe (28) is connected to a high-pressure communication pipe (58).

  Since other configurations are the same as those of the first embodiment, description thereof is omitted.

-Driving action-
Next, the operation of the air conditioner (1) will be described. Also in Embodiment 5, the air conditioner (1) can be switched between a cooling operation (see FIG. 14) and a heating operation (see FIG. 13). In addition, since it is the same as that of Embodiment 1 about air_conditionaing | cooling operation operation and heating operation operation, description is abbreviate | omitted.

(Control of suction volume ratio changing means)
Also in the fifth embodiment, when the operating condition of the air conditioner (1) changes, the suction volume ratio Vr is changed by the suction volume ratio changing means (2). Specifically, when the operating conditions change, the controller (not shown) switches the sixth three-way valve (95) constituting the switching mechanism to the first position or the second position, and the suction volume ratio Vr is changed.

  More specifically, when the sixth three-way valve (95) is switched to the second position, the refrigerant is compressed in all the compression mechanism portions of the three compression mechanism portions (31, 32, 33). It becomes a state. On the other hand, when the sixth three-way valve (95) is switched to the first position, the suction side and the discharge side of the third compression mechanism section (33) become substantially equal in pressure state, and the refrigerant is compressed in the third compression state. While passing through the mechanism portion (33) without compression, the first compression mechanism portion (31) and the second compression mechanism portion (32) are in the second state in which the refrigerant is compressed. In Embodiment 5, when switching to heating operation, the sixth three-way valve (95) is switched to the second position to enter the first state, and when switching to cooling operation, the sixth three-way valve (95). (95) is switched to the first position to enter the second state. Hereinafter, the relationship between each state and the suction volume ratio Vr will be described in detail.

  As shown in FIG. 13, in the first state, the low pressure gas branch pipe (25a) and the second communication pipe (27) communicate with each other.

  As a result, the low-pressure gas state refrigerant in the low-pressure gas pipe (25) is first sucked into the first compression mechanism part (31), and a part of the refrigerant is connected to the middle part of the low-pressure gas pipe (25). The gas is drawn into the third compression mechanism (33) through the gas branch pipe (25a) and the second communication pipe (27). Then, the first compression mechanism portion (31) and the third compression mechanism portion (33) are respectively compressed until they reach an intermediate pressure state.

  The refrigerant compressed to the intermediate pressure state in the third compression mechanism part (33) flows into the middle part of the first connection pipe (26) through the first connection joining pipe (26a). On the other hand, the refrigerant compressed to the intermediate pressure state in the first compression mechanism section (31) flows into the first communication pipe (26) and merges with the refrigerant flowing in from the first communication junction pipe (26a). The air is sucked into the second compression mechanism (32). The gas refrigerant separated from the liquid refrigerant in the gas-liquid separator (14) is disposed downstream of the first connecting pipe (26a) of the first connecting pipe (26) via the injection pipe (20). Inflow. Therefore, the refrigerant flowing through the first communication pipe (26) is sucked into the second compression mechanism section (32) after being cooled by the gas refrigerant flowing in from the injection pipe (20).

  The refrigerant sucked into the second compression mechanism section (32) is compressed in the second compression mechanism section (32) until it reaches a high pressure state. And the refrigerant | coolant compressed until it became a high pressure state in the 2nd compression mechanism part (32) is discharged by the internal space (S1) of a casing (40) via a 3rd connecting pipe (28), and is eventually discharged by high pressure. It flows into the high-pressure gas pipe (21) through the pipe (56).

  Thus, in the first state, the first compression mechanism portion (31) and the third compression mechanism portion (33) are connected in parallel and used as the low-stage compression mechanism, while the second compression mechanism portion (32). Is used as a high-stage compression mechanism. As a result, in the first state, the suction volume of the low-stage compression mechanism is the sum of the suction volume V1 of the first compression mechanism section (31) and the suction volume V3 of the third compression mechanism section (33). The suction volume of the compression mechanism is the suction volume V2 of the second compression mechanism section (32). Therefore, the suction volume ratio Vr is V2 / (V1 + V3).

  On the other hand, as shown in FIG. 14, in the second state, the first connecting branch pipe (26b) and the second connecting pipe (27) communicate with each other. As described above, the first connecting branch pipe (26b) is connected to the first connecting pipe (26), and the first connecting pipe (26) is discharged through the first connecting junction pipe (26a). Connected to tube (57). The second communication pipe (27) is connected to the third suction pipe (55). Therefore, in the second state, the suction side and the discharge side of the third compression mechanism section (33) communicate with each other and are in a substantially equal pressure state. Therefore, the refrigerant flows in the three compression mechanisms (31, 32, 33) are as follows.

  The refrigerant in the low-pressure state of the low-pressure gas pipe (25) is first sucked into the first compression mechanism (31) and compressed in the first compression mechanism (31) until it reaches an intermediate pressure state.

  The refrigerant compressed to the intermediate pressure state in the first compression mechanism part (31) is sucked into the second compression mechanism part (32) through the first communication pipe (26), and a part thereof is the first. It flows into the 3rd compression mechanism part (33) through the 1st connecting branch pipe (26b) and the 2nd connecting pipe (27) connected to the middle part of the 1 connecting pipe (26). The gas refrigerant separated from the liquid refrigerant in the gas-liquid separator (14) is disposed upstream of the first communication branch pipe (26b) of the first communication pipe (26) via the injection pipe (20). Inflow. Therefore, the refrigerant flowing through the first communication pipe (26) is cooled by the gas refrigerant flowing from the injection pipe (20), and then sucked into the second compression mechanism section (32) and the third compression mechanism section (33). ).

  The refrigerant sucked into the second compression mechanism section (32) is compressed in the second compression mechanism section (32) until it reaches a high pressure state. And the refrigerant | coolant compressed until it became a high pressure state in this 2nd compression mechanism part (32) is discharged by the internal space (S1) of a casing (40) via a 3rd connecting pipe (28), and is eventually high-pressure. It flows into the high-pressure gas pipe (21) through the discharge pipe (56).

  On the other hand, the refrigerant flowing into the third compression mechanism portion (33) passes through the inside of the third compression mechanism portion (33) without being compressed in the third compression mechanism portion (33), and is thus connected to the first communication junction pipe. It flows into the middle part of the first connecting pipe (26) through (26a).

  As described above, in the second state, the first compression mechanism (31) is used as the low-stage compression mechanism and the second compression mechanism (32) is used as the high-stage compression mechanism, while the third compression mechanism. The part (33) is not used as any compression mechanism. Thereby, in the second state, the suction volume of the low-stage compression mechanism becomes the suction volume V1 of the first compression mechanism section (31), and the suction volume of the high-stage compression mechanism becomes the suction volume of the second compression mechanism section (32). The suction volume V2. Therefore, the suction volume ratio Vr is V2 / V1.

  From the above, when the sixth three-way valve (95) constituting the switching mechanism of the suction volume ratio changing means (2) is switched from the first state to the second state, the suction volume ratio Vr increases, When the state is switched from the first state to the first state, the suction volume ratio Vr decreases.

-Effect of Embodiment 5-
As described above, also in the air conditioner (1) of the fifth embodiment, the three compression mechanism parts (31, 32, 33) are provided by the sixth three-way valve (95) constituting the switching mechanism of the suction volume ratio changing means (2). ) In the first state where the refrigerant is compressed in all the compression mechanism parts and in two compression mechanism parts (31, 32) of the three compression mechanism parts (31, 32, 33), the refrigerant is compressed. On the other hand, the suction volume ratio Vr can be easily changed by switching to the second state where the refrigerant passes through the remaining one compression mechanism section (33) without being compressed.

Embodiment 6 of the Invention
The air conditioner (1) of Embodiment 6 shown in FIGS. 15 and 16 will be described. Hereinafter, differences from the first embodiment will be described.

-Overall configuration-
In the sixth embodiment, the suction volume ratio changing means (2) includes the first state in which the refrigerant is compressed in all the compression mechanism portions of the three compression mechanism portions (31, 32, 33), and the three compression mechanism portions. The refrigerant is compressed in the two compression mechanism portions (32, 33) of (31, 32, 33), while the refrigerant passes through the remaining one compression mechanism portion (31) without being compressed. A switching mechanism for switching between the two states.

  Specifically, the switching mechanism is constituted by a seventh three-way valve (96). The seventh three-way valve (96) includes first to third ports (P1, P2, P3), a first position where the first port (P1) and the second port (P2) communicate with each other, The port (P2) and the third port (P3) can be switched to a second position where they communicate.

  Also in Embodiment 6, the high-pressure discharge pipe (56) is connected to the first port (P1) of the four-way valve (17) via the high-pressure gas pipe (21). One end of the low pressure gas pipe (25) is connected to the third port (P3) of the four-way valve (17), and the other end of the low pressure gas pipe (25) is connected to the second suction pipe (53). ing. One end of the low-pressure gas branch pipe (25a) is connected to the middle part of the low-pressure gas pipe (25), and the other end of the low-pressure gas branch pipe (25a) is the third of the seventh three-way valve (96). Connected to port (P3). Furthermore, one end of the first connecting pipe (26) is connected to the second port (P2) of the seventh three-way valve (96), and the other end of the first connecting pipe (26) is connected to the first suction pipe ( 51) is connected.

  One end of a second connecting pipe (27) is connected to the second discharge pipe (54), and the other end of the second connecting pipe (27) is connected to a third suction pipe (55). One end of the second connecting / merging pipe (27a) is connected to the middle part of the second connecting pipe (27), and the other end of the second connecting / merging pipe (27a) is connected to the first discharge pipe (52). ing. In addition, one end of the second connecting branch pipe (27b) is connected to the third suction pipe (55) side of the connecting portion of the second connecting pipe (27) of the second connecting junction pipe (27a). The other end of the two connecting branch pipe (27b) is connected to the first port (P1) of the seventh three-way valve (96). Furthermore, between the connection part of the 2nd connection junction pipe (27a) of the 2nd connection pipe (27) and the connection part of the 2nd connection branch pipe (27b), one end is connected to the said gas-liquid separator (14). The other end of the connected injection pipe (20) is connected. The injection pipe (20) cools the refrigerant being compressed by joining the gas refrigerant separated by the gas-liquid separator (14) with the refrigerant being compressed in the compressor (11). The cooling means is configured.

  Since other configurations are the same as those of the first embodiment, description thereof is omitted.

-Driving action-
Next, the operation of the air conditioner (1) will be described. Also in the sixth embodiment, the air conditioner (1) can be switched between a cooling operation (see FIG. 16) and a heating operation (see FIG. 15). In addition, since it is the same as that of Embodiment 1 about air_conditionaing | cooling operation operation and heating operation operation, description is abbreviate | omitted.

(Control of suction volume ratio changing means)
Also in the sixth embodiment, when the operating condition of the air conditioner (1) changes, the suction volume ratio Vr is changed by the suction volume ratio changing means (2). Specifically, when the operating condition changes, the seventh three-way valve (96) constituting the switching mechanism is switched to the first position or the second position by a controller (not shown) to change the suction volume ratio Vr.

  More specifically, when the seventh three-way valve (96) is switched to the second position, the refrigerant is compressed in all the compression mechanism portions of the three compression mechanism portions (31, 32, 33). It becomes a state. On the other hand, when the seventh three-way valve (96) is switched to the first position, the suction side and the discharge side of the second compression mechanism section (32) become substantially equal in pressure, and the refrigerant is compressed in the second compression state. While passing through the mechanism portion (32) without compression, the first compression mechanism portion (31) and the third compression mechanism portion (33) are in the second state in which the refrigerant is compressed. Further, in the sixth embodiment, the seventh three-way valve (96) is switched to the second position when switched to the heating operation to be in the first state, and the seventh three-way valve is switched to the cooling operation. (96) is switched to the first position to enter the second state. Hereinafter, the relationship between each state and the suction volume ratio Vr will be described in detail.

  As shown in FIG. 15, in the first state, the low-pressure gas branch pipe (25a) and the first communication pipe (26) communicate with each other.

  Thereby, the low-pressure gas state refrigerant in the low-pressure gas pipe (25) is sucked into the second compression mechanism part (32), and a part of the low-pressure gas is connected to the middle part of the low-pressure gas pipe (25). The air is sucked into the first compression mechanism (31) through the branch pipe (25a) and the first communication pipe (26). Then, the first compression mechanism portion (31) and the second compression mechanism portion (32) are respectively compressed until they reach an intermediate pressure state.

  The refrigerant compressed to the intermediate pressure state in the first compression mechanism part (31) flows into the middle part of the second connection pipe (27) through the second connection joining pipe (27a). On the other hand, the refrigerant compressed to the intermediate pressure state in the second compression mechanism section (32) flows into the second communication pipe (27) and merges with the refrigerant flowing in from the second communication junction pipe (27a). Sucked into the third compression mechanism (33). The gas refrigerant separated from the liquid refrigerant in the gas-liquid separator (14) is disposed downstream of the second connecting pipe (27a) of the second connecting pipe (27) via the injection pipe (20). Inflow. Therefore, the refrigerant flowing through the second communication pipe (27) is cooled by the gas refrigerant flowing from the injection pipe (20) and then sucked into the third compression mechanism section (33).

  The refrigerant sucked into the third compression mechanism part (33) is compressed in the third compression mechanism part (33) until it reaches a high pressure state. And the refrigerant | coolant compressed until it became a high pressure state in the 3rd compression mechanism part (33) is discharged by the internal space (S1) of a casing (40), and a high pressure gas pipe is finally passed through a high pressure discharge pipe (56). Flows into (21).

  Thus, in the first state, the first compression mechanism portion (31) and the second compression mechanism portion (32) are connected in parallel and used as the low-stage compression mechanism, while the third compression mechanism portion (33). Is used as a high-stage compression mechanism. As a result, in the first state, the suction volume of the low-stage compression mechanism is the sum of the suction volume V1 of the first compression mechanism section (31) and the suction volume V2 of the second compression mechanism section (32). The suction volume of the compression mechanism is the suction volume V3 of the third compression mechanism section (33). Therefore, the suction volume ratio Vr is V3 / (V1 + V2).

  On the other hand, as shown in FIG. 16, in the second state, the second connecting branch pipe (27b) and the first connecting pipe (26) communicate with each other. As described above, the second connecting branch pipe (27b) is connected to the second connecting pipe (27), and one end of the second connecting pipe (27) is connected to the first discharge pipe (52). The other end of the second connecting junction pipe (27a) is connected. The first communication pipe (26) is connected to the first suction pipe (51). Therefore, in the second state, the suction side and the discharge side of the first compression mechanism section (31) communicate with each other and are in a substantially equal pressure state. Therefore, the refrigerant flows in the three compression mechanisms (31, 32, 33) are as follows.

  The refrigerant in the low-pressure state of the low-pressure gas pipe (25) is first sucked into the second compression mechanism part (32) and compressed in the second compression mechanism part (32) until it reaches an intermediate pressure state.

  The refrigerant compressed to the intermediate pressure state in the second compression mechanism part (32) is sucked into the third compression mechanism part (33) through the second communication pipe (27), and a part thereof is the first. It flows into the 1st compression mechanism part (31) through the 2nd connecting branch pipe (27b) and the 1st connecting pipe (26) connected to the middle part of the 2 connecting pipe (27). The gas refrigerant separated from the liquid refrigerant in the gas-liquid separator (14) passes through the injection pipe (20) upstream of the second communication branch pipe (27b) of the second communication pipe (27). Inflow. Therefore, the refrigerant flowing through the second connecting pipe (27) is cooled by the gas refrigerant flowing from the injection pipe (20), and then sucked into the third compression mechanism section (33) and the first compression mechanism section (31 ).

  The refrigerant sucked into the third compression mechanism part (33) is compressed in the third compression mechanism part (33) until it reaches a high pressure state. And the refrigerant | coolant compressed until it became a high pressure state in the 3rd compression mechanism part (33) is discharged by the internal space (S1) of a casing (40), and a high pressure gas pipe is finally passed through a high pressure discharge pipe (56). Flows into (21).

  On the other hand, the refrigerant that has flowed into the first compression mechanism section (31) passes through the inside of the first compression mechanism section (31) without being compressed in the first compression mechanism section (31), and the second communication joining pipe. It flows into the middle part of the second connecting pipe (27) through (27a).

  As described above, in the second state, the second compression mechanism (32) is used as the low-stage compression mechanism and the third compression mechanism (33) is used as the high-stage compression mechanism, while the first compression mechanism. The part (31) is not used as any compression mechanism. Thereby, in the second state, the suction volume of the low-stage compression mechanism becomes the suction volume V2 of the second compression mechanism section (32), and the suction volume of the high-stage compression mechanism becomes the suction volume of the third compression mechanism section (33). The suction volume is V3. Therefore, the suction volume ratio Vr is V3 / V2.

  As described above, when the seventh state three-way valve (96) constituting the switching mechanism of the suction volume ratio changing means (2) is switched from the first state to the second state, the suction volume ratio Vr increases, When the state is switched from the first state to the first state, the suction volume ratio Vr decreases.

-Effect of Embodiment 6-
As described above, also in the air conditioner (1) of the sixth embodiment, the three compression mechanism sections (31, 32, 33) are formed by the seventh three-way valve (96) constituting the switching mechanism of the suction volume ratio changing means (2). ) In the first state where the refrigerant is compressed in all the compression mechanism parts and in two compression mechanism parts (32, 33) of the three compression mechanism parts (31, 32, 33). On the other hand, the suction volume ratio Vr can be easily changed by switching to the second state in which the refrigerant passes through the remaining one compression mechanism (31) without being compressed.

<< Embodiment 7 of the Invention >>
The air conditioner (1) of the seventh embodiment shown in FIGS. 17 and 18 will be described. Hereinafter, differences from the first embodiment will be described.

-Overall configuration-
In the seventh embodiment, the suction volume ratio changing means (2) includes the first state in which the refrigerant is compressed in all the compression mechanism portions of the three compression mechanism portions (31, 32, 33), and the three compression mechanism portions. The refrigerant is compressed in the two compression mechanism portions (31, 33) of (31, 32, 33), while the refrigerant passes through the remaining one compression mechanism portion (32) without being compressed. A switching mechanism for switching between the two states.

  Specifically, the switching mechanism includes an eighth three-way valve (97) and a ninth three-way valve (98). The eighth three-way valve (97) and the ninth three-way valve (98) have first to third ports (P1, P2, P3), respectively, and the first port (P1) and the second port (P2) communicate with each other. And a second position where the second port (P2) and the third port (P3) communicate with each other.

  Also in Embodiment 7, the high-pressure discharge pipe (56) is connected to the first port (P1) of the four-way valve (17) through the high-pressure gas pipe (21). One end of the low pressure gas pipe (25) is connected to the third port (P3) of the four-way valve (17). The other end of the low pressure gas pipe (25) is connected to the first suction pipe (51).

  One end of the first connecting pipe (26) is connected to the first discharge pipe (52), and the other end of the first connecting pipe (26) is connected to the second suction pipe (53). One end of the first connecting / merging pipe (26a) is connected to the middle part of the first connecting pipe (26), and the other end of the first connecting / merging pipe (26a) is connected to the eighth three-way valve (97). Connected to the first port (P1). In addition, one end of the first connection branch pipe (26b) is connected to the second suction pipe (53) side of the connection part of the first connection junction pipe (26a) in the middle of the first connection pipe (26). The other end of the first connecting branch pipe (26b) is connected to the first port (P1) of the ninth three-way valve (98). Furthermore, between the connection part of the 1st connection junction pipe (26a) of the 1st connection pipe (26) and the connection part of the 1st connection branch pipe (26b), one end is said gas-liquid separator (14). The other end of the connected injection pipe (20) is connected. The injection pipe (20) cools the refrigerant being compressed by joining the gas refrigerant separated by the gas-liquid separator (14) with the refrigerant being compressed in the compressor (11). The cooling means is configured.

  One end of a second connecting pipe (27) is connected to the second discharge pipe (54), and the other end of the second connecting pipe (27) is connected to the second port (P2 of the eighth three-way valve (97). )It is connected to the. One end of a third connecting pipe (28) is connected to the third port (P3) of the eighth three-way valve (97), and the other end of the third connecting pipe (28) is the ninth three-way valve (98). Connected to the third port (P3). The second port (P2) of the ninth three-way valve (98) is connected to one end of the fourth connecting pipe (29), and the other end of the fourth connecting pipe (29) is connected to the third suction pipe (55). It is connected to the.

  Since other configurations are the same as those of the first embodiment, description thereof is omitted.

-Driving action-
Next, the operation of the air conditioner (1) will be described. Also in Embodiment 7, the air conditioner (1) can be switched between a cooling operation (see FIG. 17) and a heating operation (see FIG. 18). In addition, since it is the same as that of Embodiment 1 about air_conditionaing | cooling operation operation and heating operation operation, description is abbreviate | omitted.

(Control of suction volume ratio changing means)
Also in the seventh embodiment, when the operating condition of the air conditioner (1) changes, the suction volume ratio Vr is changed by the suction volume ratio changing means (2). Specifically, when the operating condition changes, the controller (not shown) switches the eighth three-way valve (97) and the ninth three-way valve (98) constituting the switching mechanism to the first position or the second position, and the suction is performed. The volume ratio Vr is changed.

  More specifically, when the eighth three-way valve (97) and the ninth three-way valve (98) are switched to the second position, in all the compression mechanism portions of the three compression mechanism portions (31, 32, 33). It will be in the 1st state where a refrigerant is compressed. On the other hand, when the eighth three-way valve (97) and the ninth three-way valve (98) are switched to the first position, a pressure state in which the suction side and the discharge side of the second compression mechanism section (32) are substantially equal. The refrigerant passes through the second compression mechanism section (32) without compression, while the first compression mechanism section (31) and the third compression mechanism section (33) are in a second state where the refrigerant is compressed. Become. In the seventh embodiment, when switching to the cooling operation, the eighth three-way valve (97) and the ninth three-way valve (98) are switched to the second position to be in the first state and switched to the heating operation. At that time, the eighth three-way valve (97) and the ninth three-way valve (98) are switched to the first position to be in the second state. Hereinafter, the relationship between each state and the suction volume ratio Vr will be described in detail.

  As shown in FIG. 17, in the first state, the second communication pipe (27) and the third communication pipe (28) communicate with each other, and the third communication pipe (28) and the fourth communication pipe (29). And communicate.

  As a result, the refrigerant in the low pressure state of the low pressure gas pipe (25) is first sucked into the first compression mechanism (31) and compressed in the first compression mechanism (31) until it reaches an intermediate pressure state.

  The refrigerant compressed to the intermediate pressure state in the first compression mechanism section (31) is sucked into the second compression mechanism section (32) through the first communication pipe (26). The gas refrigerant separated from the liquid refrigerant in the gas-liquid separator (14) flows into the middle part of the first communication pipe (26) through the injection pipe (20). Therefore, the refrigerant flowing through the first communication pipe (26) is sucked into the second compression mechanism section (32) after being cooled by the gas refrigerant flowing in from the injection pipe (20).

  The refrigerant sucked into the second compression mechanism part (32) is compressed in the second compression mechanism part (32). And the refrigerant | coolant compressed in the 2nd compression mechanism part (32) passes a 2nd connection pipe (27), a 3rd connection pipe (28), and a 4th connection pipe (29), and becomes a 3rd compression mechanism part (33). ) And compressed in the third compression mechanism (33) until a high pressure state is reached.

  The refrigerant compressed to the high pressure state in the third compression mechanism section (33) is discharged into the internal space (S1) of the casing (40), and eventually the high pressure gas pipe (21 through the high pressure discharge pipe (56). ).

  Thus, in the first state, the first compression mechanism (31) is used as the low-stage compression mechanism, while the second compression mechanism (32) and the third compression mechanism (33) are connected in series. Used as a high-stage compression mechanism. Thus, in the first state, the suction volume of the low-stage compression mechanism is the suction volume V1 of the first compression mechanism section (31), and the suction volume of the high-stage compression mechanism is the upstream second compression mechanism section ( 32). Therefore, the suction volume ratio Vr is V2 / V1.

  On the other hand, as shown in FIG. 18, in the second state, the second communication pipe (27) communicates with the first communication junction pipe (26a) and the first communication branch pipe (26b) communicates with the fourth communication. The pipe (29) communicates. As described above, the first connecting pipe (26) is connected to the second suction pipe (53), and the first connecting branch pipe (26b) is connected to the first connecting pipe (26). The first communication pipe (26) is connected to the first communication junction pipe (26a) communicating with the second discharge pipe (54) through the second communication pipe (27). Therefore, in the second state, the suction side and the discharge side of the second compression mechanism section (32) communicate with each other and are in a substantially equal pressure state. Therefore, the refrigerant flows in the three compression mechanisms (31, 32, 33) are as follows.

  The refrigerant in the low-pressure state of the low-pressure gas pipe (25) is first sucked into the first compression mechanism (31) and compressed in the first compression mechanism (31) until it reaches an intermediate pressure state.

  The refrigerant compressed to the intermediate pressure state in the first compression mechanism part (31) flows into the second compression mechanism part (32) through the first connecting pipe (26), and a part thereof is the first. The air is sucked into the third compression mechanism (33) through the first connecting branch pipe (26b) and the fourth connecting pipe (29) connected to the middle part of the connecting pipe (26). The gas refrigerant separated from the liquid refrigerant in the gas-liquid separator (14) is disposed upstream of the first communication branch pipe (26b) of the first communication pipe (26) via the injection pipe (20). Inflow. Therefore, the refrigerant flowing through the first communication pipe (26) is cooled by the gas refrigerant flowing from the injection pipe (20), and then flows into the second compression mechanism section (32) and the third compression mechanism section (33). Inhaled.

  The refrigerant flowing into the second compression mechanism part (32) passes through the inside of the second compression mechanism part (32) without being compressed in the second compression mechanism part (32), and the second communication pipe (27). And it flows into the middle part of the 1st connecting pipe (26) through the 1st connecting pipe (26a).

  On the other hand, the refrigerant sucked into the third compression mechanism part (33) is compressed in the third compression mechanism part (33) until it reaches a high pressure state. And the refrigerant | coolant compressed until it became a high pressure state in the 3rd compression mechanism part (33) is discharged by the internal space (S1) of a casing (40), and a high pressure gas pipe is finally passed through a high pressure discharge pipe (56). Flows into (21).

  Thus, in the second state, the first compression mechanism (31) is used as the low-stage compression mechanism and the third compression mechanism (33) is used as the high-stage compression mechanism, while the second compression mechanism. The part (32) is not used as any compression mechanism. Thus, in the second state, the suction volume of the low-stage compression mechanism becomes the suction volume V1 of the first compression mechanism part (31), and the suction volume of the high-stage compression mechanism becomes the suction volume of the third compression mechanism part (33). The suction volume is V3. Therefore, the suction volume ratio Vr is V3 / V1.

  From the above, when the eighth three-way valve (97) and the ninth three-way valve (98) constituting the switching mechanism of the suction volume ratio changing means (2) are switched from the first state to the second state, the suction volume ratio While Vr decreases, the suction volume ratio Vr increases when the second state is switched to the first state.

-Effect of Embodiment 7-
As described above, the air compression apparatus (1) of the seventh embodiment also performs the three compressions by the eighth three-way valve (97) and the ninth three-way valve (98) that constitute the switching mechanism of the suction volume ratio changing means (2). A first state in which the refrigerant is compressed in all the compression mechanism parts of the mechanism parts (31, 32, 33), and two compression mechanism parts (31, 31) of the three compression mechanism parts (31, 32, 33) In 33), the suction volume ratio Vr is easily changed by switching to the second state in which the refrigerant is compressed while the refrigerant is compressed in the remaining one compression mechanism (32). Can do.

<< Embodiment 8 of the Invention >>
The air conditioner (1) of Embodiment 8 shown in FIGS. 19 and 20 will be described. Hereinafter, differences from the first embodiment will be described.

-Overall configuration-
In the eighth embodiment, the suction volume ratio changing means (2) has a switching mechanism for changing the position of the intermediate stage of the compressor (11). The switching mechanism is configured to be able to change the connection destination of the injection pipe (20) constituting the cooling means for cooling the refrigerant between the low-stage side compression mechanism and the high-stage side compression mechanism.

  Specifically, the switching mechanism is constituted by a tenth three-way valve (99). The tenth three-way valve (99) includes first to third ports (P1, P2, P3), a first position where the first port (P1) and the second port (P2) communicate with each other, The port (P2) and the third port (P3) can be switched to a second position where they communicate.

  Also in the eighth embodiment, the high-pressure discharge pipe (56) is connected to the first port (P1) of the four-way valve (17) through the high-pressure gas pipe (21). One end of the low pressure gas pipe (25) is connected to the third port (P3) of the four-way valve (17). The other end of the low pressure gas pipe (25) is connected to the first suction pipe (51).

  One end of the first connecting pipe (26) is connected to the first discharge pipe (52), and the other end of the first connecting pipe (26) is connected to the second suction pipe (53). Further, one end of the second communication pipe (27) is connected to the second discharge pipe (54), and the other end of the second communication pipe (27) is connected to the third suction pipe (55). .

  In the eighth embodiment, the other end of the injection pipe (20) having one end connected to the gas-liquid separator (14) is connected to the second port (P2) of the tenth three-way valve (99). One end of the first injection pipe (28) is connected to the first port (P1) of the tenth three-way valve (99), and the other end of the first injection pipe (28) is connected to the first communication pipe (26 ) Is connected to the middle part. Further, one end of the second injection pipe (29) is connected to the third port (P3) of the tenth three-way valve (99), and the other end of the second injection pipe (29) is connected to the second communication pipe (27 ) Is connected to the middle part.

  The injection pipe (20) cools the refrigerant being compressed by joining the gas refrigerant separated by the gas-liquid separator (14) with the refrigerant being compressed in the compressor (11). The cooling means is configured.

  Since other configurations are the same as those of the first embodiment, description thereof is omitted.

-Driving action-
Next, the operation of the air conditioner (1) will be described. Also in Embodiment 8, the air conditioner (1) can be switched between a cooling operation (see FIG. 19) and a heating operation (see FIG. 20). In addition, since it is the same as that of Embodiment 1 about air_conditionaing | cooling operation operation and heating operation operation, description is abbreviate | omitted.

(Control of suction volume ratio changing means)
Also in the eighth embodiment, when the operating condition of the air conditioner (1) changes, the suction volume ratio Vr is changed by the suction volume ratio changing means (2). Specifically, when the operating conditions change, the controller (not shown) switches the tenth three-way valve (99) constituting the switching mechanism to the first position or the second position, thereby changing the suction volume ratio Vr.

  More specifically, when the tenth three-way valve (99) is switched to the first position, the injection pipe (20) constituting the cooling means is connected to the first compression mechanism part (31) and the second compression mechanism part (32). ) Is connected to the first state. On the other hand, when the tenth three-way valve (99) is switched to the second position, the injection pipe (20) constituting the cooling means is located between the second compression mechanism part (32) and the third compression mechanism part (33). It will be in the 2nd state connected to. In the eighth embodiment, the tenth three-way valve (99) is switched to the first position when switched to the cooling operation to be in the first state, and the tenth three-way valve is switched to the heating operation. (99) is switched to the second position to enter the second state. Hereinafter, the relationship between each state and the suction volume ratio Vr will be described in detail.

  As shown in FIG. 19, in the first state, the injection pipe (20) and the first injection pipe (28) communicate with each other. Since the 1st injection pipe (28) is connected to the middle part of the 1st connecting pipe (26) which connects the 1st compression mechanism part (31) and the 2nd compression mechanism part (32), it is the 1st In the state, the injection pipe (20) is connected between the first compression mechanism part (31) and the second compression mechanism part (32) via the first injection pipe (28). Therefore, the refrigerant flows in the three compression mechanisms (31, 32, 33) are as follows.

  The refrigerant in the low-pressure state of the low-pressure gas pipe (25) is first sucked into the first compression mechanism (31) and compressed in the first compression mechanism (31) until it reaches an intermediate pressure state.

  The refrigerant compressed to the intermediate pressure state in the first compression mechanism section (31) is sucked into the second compression mechanism section (32) through the first communication pipe (26). The gas refrigerant separated from the liquid refrigerant in the gas-liquid separator (14) flows into the middle part of the first communication pipe (26) through the injection pipe (20) and the first injection pipe (28). . Therefore, the refrigerant flowing through the first communication pipe (26) is sucked into the second compression mechanism section (32) after being cooled by the gas refrigerant flowing in from the injection pipe (20).

  The refrigerant sucked into the second compression mechanism part (32) is compressed in the second compression mechanism part (32), and sucked into the third compression mechanism part (33) through the second connecting pipe (27). . The refrigerant sucked into the third compression mechanism part (33) is compressed in the third compression mechanism part (33) until it reaches a high pressure state.

  The refrigerant compressed to the high pressure state in the third compression mechanism section (33) is discharged into the internal space (S1) of the casing (40), and eventually the high pressure gas pipe (21 through the high pressure discharge pipe (56). ).

  Thus, in the first state, the refrigerant between the first compression mechanism part (31) and the second compression mechanism part (32) is cooled by the gas refrigerant separated from the liquid refrigerant in the gas-liquid separator (14). Is done. Thereby, while the 1st compression mechanism part (31) is used as a low stage compression mechanism, the 2nd compression mechanism part (32) and the 3rd compression mechanism part (33) are connected in series, and a high stage compression mechanism Will be used. As a result, in the first state, the suction volume of the low-stage compression mechanism is the suction volume V1 of the first compression mechanism section (31), and the suction volume of the high-stage compression mechanism is the upstream second compression mechanism section ( 32). Therefore, the suction volume ratio Vr is V2 / V1.

  On the other hand, in the second state, the injection pipe (20) and the second injection pipe (29) communicate with each other. Since the 2nd injection pipe (29) is connected to the middle part of the 2nd connecting pipe (27) which connects the 2nd compression mechanism part (32) and the 3rd compression mechanism part (33), it is 2nd In the state, the injection pipe (20) is connected between the second compression mechanism part (32) and the third compression mechanism part (33) via the second injection pipe (29). Therefore, the refrigerant flows in the three compression mechanisms (31, 32, 33) are as follows.

  The refrigerant in the low pressure state of the low pressure gas pipe (25) is first sucked into the first compression mechanism (31) and compressed. Then, the refrigerant compressed in the first compression mechanism part (31) is sucked into the second compression mechanism part (32) through the first connecting pipe (26), and is intermediated in the second compression mechanism part (32). Compressed until pressure is reached.

  The refrigerant compressed to the intermediate pressure state in the second compression mechanism section (32) is sucked into the third compression mechanism section (33) through the second communication pipe (27), and the third compression mechanism section ( In 33), it is compressed until it reaches a high pressure state. In addition, the gas refrigerant separated from the liquid refrigerant in the gas-liquid separator (14) flows into the middle part of the second communication pipe (27) through the injection pipe (20) and the second injection pipe (29). . Therefore, the refrigerant flowing through the second communication pipe (27) is cooled by the gas refrigerant flowing from the injection pipe (20) and then sucked into the third compression mechanism section (33).

  The refrigerant compressed to the high pressure state in the third compression mechanism section (33) is discharged into the internal space (S1) of the casing (40), and eventually the high pressure gas pipe (21 through the high pressure discharge pipe (56). ).

  Thus, in the second state, the refrigerant between the second compression mechanism part (32) and the third compression mechanism part (33) is cooled by the gas refrigerant separated from the liquid refrigerant in the gas-liquid separator (14). Is done. As a result, the first compression mechanism section (31) and the second compression mechanism section (32) are connected in series and used as a low-stage compression mechanism, while the third compression mechanism section (33) is used as a high-stage compression mechanism. Used as As a result, in the first state, the suction volume of the low-stage compression mechanism is the suction volume V1 of the upstream first compression mechanism section (31), and the suction volume of the high-stage compression mechanism is the third compression mechanism section ( 33). Therefore, the suction volume ratio Vr is V3 / V1.

  As described above, when the tenth three-way valve (99) constituting the switching mechanism of the suction volume ratio changing means (2) is switched from the first state to the second state, the suction volume ratio Vr is decreased while the second volume When the state is switched from the first state to the first state, the suction volume ratio Vr increases.

-Effect of Embodiment 8-
As described above, also in the air conditioner (1) of the eighth embodiment, the position of the intermediate stage of the compressor (11) is changed by the tenth three-way valve (99) constituting the switching mechanism of the suction volume ratio changing means (2). By changing, the suction volume ratio Vr can be easily changed.

  In the eighth embodiment, the first compression mechanism section (31) constitutes the first compression mechanism section according to the present invention, and the second compression mechanism section (32) is the second compression mechanism section according to the present invention. The third compression mechanism part (33) constitutes the third compression mechanism part according to the present invention. However, the configurations of the first compression mechanism unit, the second compression mechanism unit, and the third compression mechanism unit according to the present invention are not limited to this, and for example, the second compression mechanism unit (32) is the first compression mechanism unit according to the present invention. 1 compression mechanism part, the 1st compression mechanism part (31) constitutes the 2nd compression mechanism part concerning the present invention, and the 3rd compression mechanism part (33) concerning the 3rd compression mechanism part concerning the present invention (33) may be configured.

<< Other Embodiments >>
About each embodiment mentioned above, it is good also as following structures.

  In each of the above embodiments, the refrigerant filled in the refrigerant circuit (10) may be a refrigerant other than carbon dioxide (for example, a fluorocarbon refrigerant).

  In each of the above embodiments, the three compression mechanisms (31, 32, 33) are so-called oscillating pistons in which the blades (63, 73, 83) are integrally formed with the pistons (62, 72, 82). The three compression mechanisms (31, 32, 33) were formed separately from the pistons (62, 72, 82) with the blades (63, 73, 83). It may be constituted by a so-called rolling piston type compression mechanism.

  In each of the above embodiments, the injection pipe (20) is used as a cooling means for cooling the refrigerant in the intermediate stage of the compressor (11). However, a heat exchanger (intercooler) may be used as the cooling means. Good.

  In each of the above embodiments, a three-way valve or a four-way valve is used as the switching mechanism of the suction volume ratio changing means (2). However, the switching mechanism can be replaced by a plurality of electromagnetic valves.

  In each of the above embodiments, the suction volume ratio Vr is changed by the suction volume ratio changing means (2) when switching to the cooling operation or the heating operation. Needless to say, a high COP can be obtained regardless of changes in operating conditions by changing the operating conditions according to changes in various operating conditions.

  In addition, the above embodiment is an essentially preferable illustration, Comprising: It does not intend restrict | limiting the range of this invention, its application thing, or its use.

  As described above, the present invention is useful for a refrigeration apparatus for a two-stage compression refrigeration cycle.

1 is a refrigerant circuit diagram of an air-conditioning apparatus according to Embodiment 1. FIG. FIG. 2 is a longitudinal sectional view of the compressor according to the first embodiment. FIG. 3 is a cross-sectional view of the compression mechanism unit of the first embodiment. FIG. 4 is an operation state diagram of the compression mechanism unit according to the first embodiment. FIG. 5 is a refrigerant circuit diagram illustrating a refrigerant flow in the first state of the air-conditioning apparatus according to Embodiment 1. FIG. 6 is a refrigerant circuit diagram illustrating a refrigerant flow in the second state of the air-conditioning apparatus according to Embodiment 1. FIG. 7 is a refrigerant circuit diagram illustrating a refrigerant flow in the first state of the air-conditioning apparatus according to Embodiment 2. FIG. 8 is a refrigerant circuit diagram illustrating a refrigerant flow in the second state of the air-conditioning apparatus according to Embodiment 2. FIG. 9 is a refrigerant circuit diagram illustrating a refrigerant flow in the first state of the air-conditioning apparatus according to Embodiment 3. FIG. 10 is a refrigerant circuit diagram illustrating a refrigerant flow in the second state of the air-conditioning apparatus according to Embodiment 3. FIG. 11 is a refrigerant circuit diagram illustrating a refrigerant flow in the first state of the air-conditioning apparatus according to Embodiment 4. FIG. 12 is a refrigerant circuit diagram illustrating a refrigerant flow in the second state of the air-conditioning apparatus according to Embodiment 4. FIG. 13 is a refrigerant circuit diagram illustrating a refrigerant flow in the first state of the air-conditioning apparatus according to Embodiment 5. FIG. 14 is a refrigerant circuit diagram illustrating a refrigerant flow in the second state of the air-conditioning apparatus according to Embodiment 5. FIG. 15 is a refrigerant circuit diagram illustrating a refrigerant flow in the first state of the air-conditioning apparatus according to Embodiment 6. FIG. 16 is a refrigerant circuit diagram illustrating a refrigerant flow in the second state of the air-conditioning apparatus according to Embodiment 6. FIG. 17 is a refrigerant circuit diagram illustrating a refrigerant flow in the first state of the air-conditioning apparatus according to Embodiment 7. FIG. 18 is a refrigerant circuit diagram illustrating a refrigerant flow in the second state of the air-conditioning apparatus according to Embodiment 7. FIG. 19 is a refrigerant circuit diagram illustrating a refrigerant flow in the first state of the air-conditioning apparatus according to Embodiment 8. FIG. 20 is a refrigerant circuit diagram illustrating a refrigerant flow in the second state of the air-conditioning apparatus according to Embodiment 8.

Explanation of symbols

1 Air conditioning equipment (refrigeration equipment)
2 Inhalation volume ratio change means
10 Refrigerant circuit
11 Compressor
18 First three-way valve (switching mechanism)
19 Second three-way valve (switching mechanism)
31 1st compression mechanism part
32 Second compression mechanism
33 Third compression mechanism
35 Drive shaft
90 3rd three-way valve (switching mechanism)
91 Fourth three-way valve (switching mechanism)
92 Second four-way valve (switching mechanism)
93 Third four-way valve (switching mechanism)
94 Fifth three-way valve (switching mechanism)
95 Sixth three-way valve (switching mechanism)
96 Seventh three-way valve (switching mechanism)
97 Eighth three-way valve (switching mechanism)
98 Ninth three-way valve (switching mechanism)
99 10th three way valve (switching mechanism)

Claims (11)

A refrigerant having a compressor (11) in which a plurality of rotary type compression mechanisms (31, 32, 33) each having one cylinder chamber (C1, C2, C3) are connected by one drive shaft (35). A refrigeration apparatus comprising a circuit (10) for performing a two-stage compression refrigeration cycle,
The compressor (11) includes three compression mechanism portions (31, 32, 33),
A refrigeration apparatus comprising suction volume ratio changing means (2) for changing a suction volume ratio, which is a ratio of a suction volume between a low stage side compression mechanism and a high stage side compression mechanism. In claim 1,
The refrigeration apparatus, wherein the suction volume ratio changing means (2) changes the suction volume ratio by changing a connection relation of the three compression mechanisms (31, 32, 33). In claim 2,
The suction volume ratio changing means (2) includes two compression mechanism portions (31, 32) used as a low-stage compression mechanism among the three compression mechanism portions (31, 32, 33) connected in series. And a switching mechanism (18, 19) for switching between the connected state and the state connected in parallel. In claim 2,
The suction volume ratio changing means (2) includes two compression mechanism portions (32, 33) used as high-stage compression mechanisms among the three compression mechanism portions (31, 32, 33) connected in series. And a switching mechanism (90, 91) for switching between a connected state and a state connected in parallel. In claim 2,
Any two compression mechanism portions (31, 32) of the three compression mechanism portions (31, 32, 33) are configured to have different suction volumes,
The suction volume ratio changing means (2) has a switching mechanism (92, 93) for changing the connection relationship between the two compression mechanisms (31, 32) having different suction volumes. apparatus. In claim 5,
One of the two compression mechanisms (31, 32) is used as a low-stage compression mechanism, and the other is used as a high-stage compression mechanism. In claim 1,
The suction volume ratio changing means (2)
A first state in which the refrigerant is compressed in all the compression mechanism portions of the three compression mechanism portions (31, 32, 33);
While the refrigerant is compressed in two of the three compression mechanisms (31, 32, 33), the suction side and the discharge side have substantially the same pressure in the remaining one compression mechanism. A refrigerating apparatus comprising a switching mechanism (94, 95, 96, 97, 98) that switches to a second state in which the refrigerant passes through without being compressed. In claim 7,
The switching mechanism (94, 95, 96)
In the first state, any two compression mechanism portions of the three compression mechanism portions (31, 32, 33) are connected in parallel,
In the second state, the suction side and the discharge side of one compression mechanism part of the two compression mechanism parts connected in parallel in the first state are configured to communicate with each other. Refrigeration equipment. In claim 7,
Any two compression mechanism portions (32, 33) of the three compression mechanism portions (31, 32, 33) are configured to have different suction volumes,
The switching mechanism (97, 98)
In the first state, the two compression mechanism portions (32, 33) having different suction volumes are connected in series, and both compression mechanism portions (32, 33) serve as a low-stage compression mechanism or a high-stage compression mechanism. While used
In the second state, the suction side and the discharge side of the upstream compression mechanism part (32) of the two compression mechanism parts (32, 33) connected in series in the first state communicate with each other. It is comprised as follows. The freezing apparatus characterized by the above-mentioned. In claim 1,
The three compression mechanism sections (31, 32, 33) are connected in series in the order of the first compression mechanism section (31), the second compression mechanism section (32), and the third compression mechanism section (33). ,
The suction volume ratio changing means (2)
While cooling the refrigerant between the first compression mechanism part (31) and the second compression mechanism part (32) to use the first compression mechanism part (31) as a low-stage compression mechanism, A first state in which the second compression mechanism (32) and the third compression mechanism (33) are used as a high-stage compression mechanism;
The refrigerant between the second compression mechanism part (32) and the third compression mechanism part (33) is cooled to thereby provide the first compression mechanism part (31) and the second compression mechanism part (32). And a switching mechanism (98) for switching to a second state in which the third compression mechanism (33) is used as a high-stage compression mechanism. Refrigeration equipment. In any one of claims 1 to 10,
A refrigerating apparatus, wherein the refrigerant flowing through the refrigerant circuit (10) is carbon dioxide.

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