SPIRAL COMPRESSOR

Description

Technical Field

[0001] The present disclosure relates to a scroll compressor.Background Art

[0002] In recent years, in a refrigerating cycle of a refrigerating device, an air conditioning device, or the like, a refrigerant having a low global warming potential (GWP) is used, so that a temperature of the refrigerant (discharge gas) discharged from a compressor tends to increase.

[0003] In some compressors used under operating conditions having a high pressure ratio, such as a refrigerating device for low temperature, a liquid injection structure in which a refrigerant liquid is injected during a compression stroke of the compressor is adopted in order to decrease the temperature of the discharge gas (for example, PTL 1 and PTL 2). Other examples of these compressors are disclosed in WO 2019 / 207785 A1, EP 2280172 A1, WO 2006 / 031433 A2 and JP 2015113817 A.Citation ListPatent Literature

[0004] [PTL 1] Japanese Unexamined Patent Application Publication No. 2019-210867 [PTL 2] International Publication No. WO2018 / 198164 Summary of InventionTechnical Problem

[0005] However, in a configuration in which a liquid injection port for supplying a liquid refrigerant to a compression chamber is formed in a fixed scroll end plate as in PTL 1, the liquid injection port communicating with the compression chamber becomes a space (dead volume) that does not contribute to compression of the refrigerant during non-injection. Therefore, in the configuration of PTL 1, there is a possibility that a compression efficiency is decreased during non-injection.

[0006] On the other hand, in a configuration of PTL 2, since a flow passage for guiding the liquid refrigerant to the compression chamber is not formed in the fixed scroll end plate, the dead volume as in Patent Document 1 does not occur. However, since the introduced liquid refrigerant is guided to the compression chamber via a limited space on a back surface side of the fixed scroll end plate, it is not efficient from the viewpoint of cooling the fixed scroll end plate (and thus the entire fixed scroll).

[0007] The present disclosure has been made in view of such circumstances, and an object thereof is to provide a scroll compressor capable of suppressing an increase in temperature of the discharge gas and suppressing a decrease in compression efficiency during non-injection.Solution to Problem

[0008] In order to solve the above problems, the scroll compressor of the present disclosure adopts the following means.

[0009] That is, the scroll compressor according to the invention is defined in claim 1.Advantageous Effects of Invention

[0010] According to the present disclosure, it is possible to suppress an increase in temperature of the discharge gas and suppress a decrease in compression efficiency during non-injection.Brief Description of Drawings

[0011] Fig. 1 is a schematic configuration diagram of a refrigerating cycle including a scroll compressor according to an embodiment of the present disclosure. Fig. 2 is a longitudinal sectional view of the scroll compressor according to the embodiment of the present disclosure. Fig. 3 is a plan view of a fixed scroll accommodated in a housing in the scroll compressor according to the embodiment of the present disclosure. Fig. 4 is a longitudinal sectional view of a scroll compressor according to a modification example. Description of Embodiments

[0012] Hereinafter, a scroll compressor according to an embodiment of the present disclosure will be described with reference to Figs. 1 to 4. [Structure of scroll compressor]

[0013] As shown in Fig. 1, a scroll compressor 11 constitutes a refrigerating cycle 10 together with a condenser 12, an expansion valve 13, an evaporator 14, a refrigerant piping 15, and the like. The refrigerating cycle 10 further includes an injection circuit 20.

[0014] The injection circuit 20 includes an injection piping 21, and a strainer 22, a valve 23, and a capillary tube 24 that are provided in the injection piping 21.

[0015] The injection piping 21 connects the refrigerant piping 15 connected to a refrigerant outlet of the condenser 12 and the scroll compressor 11 and guides a liquid refrigerant condensed by the condenser 12 to the scroll compressor 11 (specifically, a liquid injection pipe 34 which will be described later).

[0016] The strainer 22 removes foreign matter contained in the liquid refrigerant flowing through the injection piping 21.

[0017] The valve 23 regulates a flow rate of the liquid refrigerant flowing through the injection piping 21. The valve 23 is, for example, an opening-closing valve, a flow regulation valve, or the like.

[0018] The capillary tube 24 decompresses the liquid refrigerant flowing through the injection piping 21 to a pressure suitable for liquid injection.

[0019] As shown in Fig. 2, the scroll compressor 11 is a closed-type scroll compressor and includes a housing 33 having a closed space therein, a discharge cover 40 that divides the closed space, a compression mechanism 60 that compresses a refrigerant, a drive shaft 95 for causing an orbiting scroll 80 of the compression mechanism 60 to perform revolving / orbiting motion, and an electric motor 96 for driving the drive shaft 95.

[0020] The closed space is formed inside the housing 33 by an upper housing 33A, an intermediate housing 33B, and a lower housing (not shown).

[0021] The upper housing 33A and the intermediate housing 33B are connected to each other with an outer peripheral end portion of the discharge cover 40 interposed therebetween. That is, the closed space inside the housing 33 is divided in a direction of a central axis X by the discharge cover 40. Of the divided closed spaces, the closed space corresponding to the upper housing 33A is a discharge chamber 53, and the closed space corresponding to the intermediate housing 33B is a suction chamber 55.

[0022] A discharge pipe 31 for discharging the refrigerant is provided on an upper wall of the upper housing 33A and allows the discharge chamber 53 and the outside of the upper housing 33A (housing 33) to communicate with each other.

[0023] The discharge pipe 31 is connected to the refrigerant pipe 15, and is configured to guide the refrigerant discharged from the discharge pipe 31 to the condenser 12 (see Fig. 1).

[0024] A suction pipe 32 for sucking the refrigerant is provided on a side wall of the intermediate housing 33B and allows the suction chamber 55 and the outside of the intermediate housing 33B (housing 33) to communicate with each other.

[0025] The suction pipe 32 is connected to the refrigerant pipe 15, and is configured to guide the refrigerant evaporated in the evaporator 14 to the suction chamber 55 (see Fig. 1).

[0026] The suction chamber 55 is provided with a compression mechanism 60 for compressing the refrigerant, a drive shaft 95, an electric motor 96, and a support member 97 that pivotally supports the drive shaft 95.

[0027] The compression mechanism 60 includes a fixed scroll 70 in which a spiral fixed-side wall body 75 is erected on a fixed-side end plate 71 and an orbiting scroll 80 in which a spiral orbiting-side wall body 85 is erected on an orbiting-side end plate 81.

[0028] In the fixed scroll 70 and the orbiting scroll 80, the fixed-side wall body 75 and the orbiting-side wall body 85 mesh with each other to form the compression chamber 61. A tip clearance is set in consideration of thermal expansion of each wall body between a tooth tip of the fixed-side wall body 75 and a tooth bottom of the orbiting-side end plate 81 and between a tooth tip of the orbiting-side wall body 85 and a tooth bottom of the fixed-side end plate 71.

[0029] The fixed scroll 70 is fixed to the support member 97 by fixing portions 74 formed at an outer peripheral end portion of the fixed-side end plate 71. As shown in Fig. 3, the fixing portions 74 protrude outward in a radial direction and are provided at a plurality of locations in a circumferential direction. Since the support member 97 is fixed to the intermediate housing 33B, the fixed scroll 70 is fixed to the intermediate housing 33B via the support member 97.

[0030] The "radial direction" and the "circumferential direction" referred to herein are directions with respect to the central axis X of the fixed scroll 70.

[0031] The orbiting scroll 80 is configured to perform revolving / orbiting motion with respect to the central axis X of the fixed scroll 70 by means of the drive shaft 95 and a rotation prevention mechanism (for example, an Oldham link).

[0032] The discharge cover 40 is disposed above the fixed scroll 70 (a back surface side of the fixed-side end plate 71) and defines a back pressure chamber 54 and a refrigerant flow passage 51 (including an annular flow passage 52) together with a back surface of the fixed-side end plate 71.

[0033] The details are as follows.

[0034] As shown in Figs. 2 and 3, a ridge portion 73 formed in an annular shape around the central axis X is provided on the back surface of the fixed-side end plate 71. Further, on a surface of the discharge cover 40 facing the back surface of the fixed-side end plate 71, a groove portion 42 formed in an annular shape corresponding to the shape of the ridge portion 73 is provided.

[0035] As shown in Fig. 2, the ridge portion 73 and the groove portion 42 are configured to be fitted to each other. In a state where the ridge portion 73 is fitted to the groove portion 42, a predetermined space is formed between the back surface of the fixed-side end plate 71 inside the ridge portion 73 and a surface of the discharge cover 40 inside the groove portion 42. This space serves as the back pressure chamber 54. The back pressure chamber 54 is formed in a circular shape inside the ridge portion 73.

[0036] In a state where the ridge portion 73 is fitted to the groove portion 42, a predetermined space is formed between a tip surface of the ridge portion 73 and a bottom surface of the groove portion 42. This space serves as the annular flow passage 52. The annular flow passage 52 is formed in an annular shape by the ridge portion 73 and the groove portion 42. Further, a predetermined space is formed between a surface of the fixed-side end plate 71 outside the ridge portion 73 and a surface of the discharge cover 40 outside the groove portion 42. This space and the annular flow passage 52 serve as the refrigerant flow passage 51.

[0037] An O-ring 94 is provided between an inner peripheral surface of the groove portion 42 and an inner peripheral surface of the ridge portion 73 to seal between the back pressure chamber 54 and the refrigerant flow passage 51.

[0038] On the other hand, a seal member (for example, an O-ring) is not provided between an outer peripheral surface of the groove portion 42 and an outer peripheral surface of the ridge portion 73 and gaps are formed. The gaps are formed at least at a plurality of locations (for example, over the entire circumference) along the circumferential direction. The gaps are also a part of the refrigerant flow passage 51.

[0039] As shown in Fig. 4, the O-ring may not be forcibly provided by omitting a ring groove from the outer peripheral surface of the groove portion 42. As a result, it is possible to avoid accidentally providing an unnecessary O-ring at the time of assembly.

[0040] A discharge port 72 through which the compression chamber 61 and the back pressure chamber 54 communicate with each other is formed in the fixed-side end plate 71. Further, a discharge port 41 (different from the discharge port 72 of the fixed-side end plate 71) through which the back pressure chamber 54 and the discharge chamber 53 communicate with each other is formed in the discharge cover 40. That is, the compression chamber 61 and the discharge chamber 53 communicate with each other via the discharge port 72, the back pressure chamber 54, and the discharge port 41.

[0041] In the back pressure chamber 54, a retainer 93 that regulates a reed valve 92 and a movable range of the reed valve 92 is provided at an outlet portion of the discharge port 72.

[0042] A liquid injection pipe 34 for guiding the liquid refrigerant from the injection piping 21 is provided on a wall surface of the upper housing 33A and allows the annular flow passage 52 and the outside of the upper housing 33A (housing 33) to communicate with each other.[Regarding flow of refrigerant]

[0043] In the scroll compressor 11 configured as described above, the refrigerant flows as follows.

[0044] That is, the refrigerant evaporated in the evaporator 14 (see Fig. 1) is guided from the suction pipe 32 to the suction chamber 55 of the scroll compressor 11 via the refrigerant pipe 15.

[0045] The refrigerant guided to the suction chamber 55 is taken into the compression chamber 61 from around the compression mechanism 60 (compression chamber 61). The refrigerant taken into the compression chamber 61 is compressed in the compression chamber 61 whose volume changes due to the revolving / orbiting motion of the orbiting scroll 80, and guided to the back pressure chamber 54 from the discharge port 72 formed in a central portion of the fixed-side end plate 71.

[0046] The refrigerant guided to the back pressure chamber 54 is guided to the discharge chamber 53 via the discharge port 41 formed in the discharge cover 40.

[0047] The refrigerant guided to the discharge chamber 53 is guided from the discharge pipe 31 to the condenser 12 (see Fig. 1) via the refrigerant pipe 15 connected to the discharge pipe 31.

[0048] As shown in Fig. 1, the refrigerant guided to the condenser 12 is condensed by heat exchange, a part of the liquid refrigerant is guided to the injection piping 21 as an injection liquid, and a remaining refrigerant is guided to the expansion valve 13 through the refrigerant pipe 15.

[0049] The refrigerant guided to the expansion valve 13 is expanded (decompressed) and is guided to the evaporator 14.

[0050] On the other hand, the injection liquid guided to the injection piping 21 is guided to the liquid injection pipe 34 provided in the scroll compressor 11 via the strainer 22, the valve 23, and the capillary tube 24.

[0051] As shown in Figs. 2 and 3, the injection liquid (illustrated by an arrow) guided to the liquid injection pipe 34 flows into the annular flow passage 52 of the refrigerant flow passage 51.

[0052] As shown in Fig. 3, the injection liquid that has flowed into the annular flow passage 52 diffuses along a shape of the annular flow passage 52 to fill the annular flow passage 52.

[0053] The injection liquid guided to the annular flow passage 52 flows radially outward about the central axis X from an outer peripheral edge of the annular flow passage 52 to the back surface side of the fixed-side end plate 71.

[0054] At this time, as described above, since gaps are formed at least at a plurality of locations along the circumferential direction between the outer peripheral surface of the groove portion 42 and the outer peripheral surface of the ridge portions 73, the injection liquid is caused to flow out in a plurality of directions along the circumferential direction via the gaps. For example, if the gap between the outer peripheral surface of the groove portion 42 and the outer peripheral surface of the ridge portion 73 is formed over the entire circumference, the injection liquid will flow out over an entirety of the circumferential direction.

[0055] The shape of the gap may be devised such that the injection liquid flows out smoothly. For example, a plurality of shallow grooves along the direction of the central axis X may be formed in the circumferential direction on the outer peripheral surface of the groove portion 42 and / or on the outer peripheral surface of the ridge portion 73.

[0056] As shown in Fig. 2, the injection liquid that has flowed out to the back surface side of the fixed-side end plate 71 is guided to a suction side of the compression chamber 61 via the back surface side of the fixed-side end plate 71 and an outer peripheral side of the fixed-side wall body 75 and is compressed by the compression mechanism 60 together with the refrigerant guided to the suction chamber 55 from the evaporator 14.

[0057] According to the present embodiment, the following effects are obtained.

[0058] Since the refrigerant flow passage 51 is provided inside the housing 33 and allows the back surface side of the fixed-side end plate 71 to communicate with the suction side of the compression chamber 61 via the outer peripheral side of the fixed-side wall body 75 in a plurality of directions along the circumferential direction with respect to the central axis X, the liquid refrigerant introduced as the injection liquid into the back surface side of the fixed-side end plate 71 can be guided from the back surface side of the fixed-side end plate 71 to the outer peripheral side of the fixed-side wall body 75 by the refrigerant flow passage 51. Therefore, the fixed scroll 70 can be cooled by the injection liquid. As a result, it is possible to suppress an increase in temperature of the refrigerant (discharge gas) compressed in the compression chamber 61. In addition, the thermal expansion of the fixed-side wall body 75 can be suppressed, and the tip clearance can be set small.

[0059] Further, in a case where the injection liquid is guided from the back surface side of the fixed-side end plate 71 to the suction side of the compression chamber 61 via the outer peripheral side of the fixed-side wall body 75 in the entirety of the circumferential direction with respect to the central axis X, the fixed scroll 70 can be cooled over the entirety of the circumferential direction by the injection liquid. Accordingly, the fixed scroll 70 can be cooled more efficiently.

[0060] In addition, since the injection liquid is guided to the suction side of the compression chamber 61 through the refrigerant flow passage 51 via the outer peripheral side of the fixed-side wall body 75, the sucked refrigerant sucked into the compression chamber 61 (the refrigerant guided from the evaporator 14) can be cooled. As a result, an increase in temperature of the refrigerant compressed in the compression chamber 61 can be further suppressed.

[0061] Further, since the refrigerant flow passage 51 through which the injection liquid flows is not formed in the fixed scroll 70, the refrigerant flow passage 51 does not become a dead volume even during non-injection. Therefore, it is possible to suppress a decrease in compression efficiency during non-injection.

[0062] In addition, the annular flow passage 52 can allow the injection liquid to flow out radially outward with respect to the central axis X with a simple structure.

[0063] Further, since the refrigerant flow passage 51 is defined by the discharge cover 40 and the fixed-side end plate 71, the refrigerant flow passage 51 can be defined by a simple structure without causing a dead volume in the fixed scroll 70. Further, since the annular flow passage 52 is defined by the groove portion 42 and the ridge portion 73, the annular flow passage 52 can be defined by a simple structure.

[0064] Further, since a gap is formed as a part of the refrigerant flow passage 51 between the outer peripheral surface of the groove portion 42 and the outer peripheral surface of the ridge portion 73, the injection liquid can be discharged from the outer peripheral edge of the annular flow passage 52 with a simple structure.

[0065] As shown in Fig. 4, the annular flow passage 52 may be expanded in the direction of the central axis X to increase a flow passage cross-sectional area of the annular flow passage 52.Reference Signs List

[0066] 10:Refrigerating cycle 11:Scroll compressor 12:Condenser 13:Expansion valve 14:Evaporator 15:Refrigerant piping 20:Injection circuit 21:Injection piping 22:Strainer 23:Valve 24:Capillary tube 31:Discharge pipe 32:Suction pipe 33:Housing 33A:Upper housing (housing) 33B:Intermediate housing (housing) 34:Liquid injection pipe 40:Discharge cover 41:Discharge port 42:Groove portion 51:Refrigerant flow passage 52:Annular flow passage 53:Discharge chamber 54:Back pressure chamber 55:Suction chamber 60:Compression mechanism 61:Compression chamber 70:Fixed scroll 71:Fixed-side end plate 72:Discharge port 73:Ridge portion 74:Fixing portion 75:Fixed-side wall body 80:Orbiting scroll 81:Orbiting-side end plate 85:Orbiting-side wall body 92:Reed valve 93:Retainer 94:O-ring 95:Drive shaft 96:Electric motor 97:Support member

Claims

1. A scroll compressor (11) comprising: a compression mechanism (60) including a fixed scroll (70) in which a spiral fixed-side wall body (75) is provided on a fixed-side end plate (71) and an orbiting scroll (80) that forms a compression chamber (61) for compressing a refrigerant together with the fixed-side wall body (75) and relatively performs a revolving / orbiting motion with respect to a central axis (X) of the fixed scroll (70); a housing (33) that accommodates the compression mechanism (60) therein; and a refrigerant flow passage (51) that is provided inside the housing (33) and allows a back surface side of the fixed-side end plate (71) to communicate with a suction side of the compression chamber (61) via an outer peripheral side of the fixed-side wall body (75) in a plurality of directions along a circumferential direction with respect to the central axis (X), and a liquid injection pipe (34) that is configured to guide a liquid refrigerant from outside the housing (33) to the refrigerant flow passage (51), wherein the refrigerant flow passage (51) includes an annular flow passage (52) into which the liquid refrigerant is introduced from the liquid injection pipe (34) and which is formed in an annular shape around the central axis (X) on the back surface side of the fixed-side end plate (71), and the annular flow passage (52) has an outer peripheral edge communicating with the back surface side of the fixed-side end plate (71), characterised in that it further comprises a discharge cover (40) provided on the back surface side of the fixed-side end plate (71), wherein the refrigerant flow passage (51) is defined by the discharge cover(40) and the fixed-side end plate (71).

2. The scroll compressor (11) according to Claim 1, wherein the refrigerant flow passage (51) allows the back surface side of the fixed-side end plate (71) to communicate with the suction side of the compression chamber (61) via the outer peripheral side of the fixed-side wall body (75) in an entirety of the circumferential direction with respect to the central axis (X).

3. The scroll compressor (11) according to Claim 1 or 2, wherein an annular groove (42) portion is formed around the central axis (X) on a surface of the discharge cover (40) facing a back surface of the fixed-side end plate (71), an annular ridge portion (73) that is fitted to the groove portion (42) is formed on the back surface of the fixed-side end plate (71), and the annular flow passage (52) is defined by the groove portion (42) and the ridge portion (73) that is fitted to the groove portion (42).

4. The scroll compressor (11) according to Claim 3, wherein a gap is formed between an outer peripheral surface of the groove portion (42) and an outer peripheral surface of the ridge portion (73).

5. The scroll compressor (11) according to Claim 3, wherein gaps are formed between an outer peripheral surface of the groove portion (42) and an outer peripheral surface of the ridge portion (73) at least at a plurality of locations along the circumferential direction.

6. The scroll compressor (11) according to any one of Claims 1 to 5, wherein the annular flow passage (52) is disposed on a radial inner side of the back surface side of the fixed-side end plate (71).