Screw compressor and refrigeration device

Abstract

The partition wall portion (15) includes a first enclosure portion (11) and a second enclosure portion (12). Inside the first enclosure portion (11), a first compression chamber (21) is formed by a screw rotor (40) and a first gate (51). Inside the second enclosure portion (12), a second compression chamber (22) is formed by a screw rotor (40) and a second gate (61). An axial length (D1) of the first enclosure portion (11) extending along a drive shaft (25) of the screw rotor (40) is different from an axial length (D2) of the second enclosure portion (12).

Description

Technical Field

[0001] The present invention relates to a screw compressor and a refrigeration device. Background Art

[0002] Patent Document 1 discloses a screw compressor in which a first compression chamber for compressing fluid at suction pressure to intermediate pressure and a second compression chamber for compressing fluid at intermediate pressure to discharge pressure are formed between a screw rotor and a plurality of gates.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Publication No. 2021-162021 Summary of the invention

[0006] -Technical problem to be solved by the invention-

[0007] Here, in a screw compressor capable of two-stage compression, in order to efficiently compress the refrigerant compressed in the first compression chamber on the low-stage side in the second compression chamber on the high-stage side, it is necessary to appropriately set the volume ratio between the first compression chamber and the second compression chamber.

[0008] An object of the present disclosure is to provide a screw compressor in which the volume ratio between a low-stage compression chamber and a high-stage compression chamber is appropriately set.

[0009] -Technical solutions to solve technical problems-

[0010] A first aspect of the present disclosure relates to a screw compressor, which includes a screw rotor 40, a first rotor 31, a second rotor 32, and a housing 10, wherein the screw rotor 40 has a plurality of spiral grooves 41, the first rotor 31 meshes with the spiral grooves 41 of the screw rotor 40, and the second rotor 32 meshes with the spiral grooves 41 of the screw rotor 40, the housing 10 has a partition wall portion 15, the screw rotor 40 is rotatably held by the partition wall portion 15, and the partition wall portion 15 covers the outer peripheral surface of the screw rotor 40, the partition wall portion 15 includes a first surrounding portion 11 for constituting a first compression chamber 21 and a second surrounding portion 12 for constituting a second compression chamber 22, On the inner side of the first enclosure 11, the first compression chamber 21 is formed by the screw rotor 40 and the first rotor 31. The first compression chamber 21 compresses the fluid of the suction pressure introduced into the shell 10 to an intermediate pressure higher than the suction pressure. On the inner side of the second enclosure 12, the second compression chamber 22 is formed by the screw rotor 40 and the second rotor 32. The second compression chamber 22 compresses the fluid of the intermediate pressure to a discharge pressure higher than the intermediate pressure. The axial length D1 of the first enclosure 11 extending along the drive shaft 25 of the screw rotor 40 is different from the axial length D2 of the second enclosure 12 extending along the drive shaft 25.

[0011] In the first aspect, the axial length D1 of the first enclosure 11 is different from the axial length D2 of the second enclosure 12. Thus, by changing the fully closed timing of the first compression chamber 21 and the fully closed timing of the second compression chamber 22, the volume ratio of the first compression chamber 21 to the second compression chamber 22 can be appropriately set.

[0012] A second aspect of the present disclosure relates to a screw compressor, which includes a screw rotor 40, a first rotor 31, a second rotor 32, and a housing 10, wherein the screw rotor 40 has a plurality of spiral grooves 41, the first rotor 31 meshes with the spiral grooves 41 of the screw rotor 40, and the second rotor 32 meshes with the spiral grooves 41 of the screw rotor 40, and the housing 10 has a partition wall portion 15, the screw rotor 40 is rotatably held by the partition wall portion 15, and the partition wall portion 15 covers the outer peripheral surface of the screw rotor 40, and the partition wall portion 15 includes a first surrounding portion 11 for constituting a first compression chamber 21 and a second compression chamber 21. The second enclosure 12 of the chamber 22, on the inner side of the first enclosure 11, the first compression chamber 21 is formed by the screw rotor 40 and the first rotor 31, and the first compression chamber 21 compresses the fluid of the suction pressure introduced into the shell 10 to an intermediate pressure higher than the suction pressure, and on the inner side of the second enclosure 12, the second compression chamber 22 is formed by the screw rotor 40 and the second rotor 32, and the second compression chamber 22 compresses the fluid of the intermediate pressure to a discharge pressure higher than the intermediate pressure, and the second enclosure 12 is provided with an opening portion 35 that passes through the inner surface of the second enclosure 12 to the outer surface.

[0013] In the second aspect, the opening 35 is provided in the second surrounding portion 12. Thus, by changing the full closing timing of the first compression chamber 21 and the full closing timing of the second compression chamber 22, the volume ratio of the first compression chamber 21 and the second compression chamber 22 can be appropriately set.

[0014] According to a third aspect of the present disclosure, in addition to the screw compressor according to the second aspect, the opening portion 35 is a through hole 36 formed in the second surrounding portion 12 .

[0015] In the third aspect, by forming the through hole 36 in the second surrounding portion 12 , the volume ratio between the first compression chamber 21 and the second compression chamber 22 can be appropriately set.

[0016] A fourth aspect of the present disclosure is the screw compressor of the second aspect, wherein the opening portion ( 35 ) is a notch portion ( 37 ) formed at an edge of the second surrounding portion ( 12 ).

[0017] In the fourth aspect, by forming the notch portion 37 at the edge of the second surrounding portion 12 , the volume ratio between the first compression chamber 21 and the second compression chamber 22 can be appropriately set.

[0018] According to a fifth aspect of the present disclosure, based on the screw compressor of any one of the first to fourth aspects, the first rotor 31 is composed of a first gate rotor 50 having a plurality of first gates 51 arranged radially, and the second rotor 32 is composed of a second gate rotor 60 having a plurality of second gates 61 arranged radially, and the first gates 51 and the second gates 61 are respectively engaged with the spiral groove 41 of one of the screw rotors 40.

[0019] In the fifth aspect, in the screw compressor including the single screw rotor (40), the first gate rotor (50), and the second gate rotor (60), the volume ratio between the first compression chamber (21) and the second compression chamber (22) can be appropriately set.

[0020] According to a sixth aspect of the present disclosure, in the screw compressor according to the fifth aspect, the first rotating shaft (55) of the first gate rotor (50) and the second rotating shaft (65) of the second gate rotor (60) are substantially orthogonal to an imaginary plane (F) extending along the drive shaft (25) of the screw rotor (40).

[0021] In the sixth aspect, the holes for supporting the rotating shafts of the screw rotor (40), the first gate rotor (50), and the second gate rotor (60) can be machined while the rotating tool of the machine tool is relatively moved in one direction without changing the holding form of the casing (10), thereby ensuring the machining accuracy of the casing (10).

[0022] The seventh aspect of the present disclosure is based on the screw compressor of any one of the first to fourth aspects, wherein the first rotor 31 is composed of a first female rotor 70 having a plurality of first spiral grooves 71, the second rotor 32 is composed of a second female rotor 80 having a plurality of second spiral grooves 81, and the screw rotor 40 is composed of a male rotor meshing with the first female rotor 70 and the second female rotor 80.

[0023] In the seventh aspect, in the screw compressor including one male rotor, the first female rotor (70), and the second female rotor (80), the volume ratio between the first compression chamber (21) and the second compression chamber (22) can be appropriately set.

[0024] An eighth aspect of the present disclosure is directed to a refrigeration device including the screw compressor 1 according to any one of the first to seventh aspects, and a refrigerant circuit 2 a through which the refrigerant compressed by the screw compressor 1 flows.

[0025] In an eighth aspect, a refrigeration device including the screw compressor 1 can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a refrigerant circuit diagram showing the structure of the refrigeration device according to the first embodiment;

[0027] Figure 2 This is a cross-sectional view of the structure of the screw compressor observed from the back side;

[0028] Figure 3 is a side sectional view showing the structure of a screw compressor;

[0029] Figure 4 is a perspective view showing the structure of a compression mechanism;

[0030] Figure 5 is a top view showing the structure of the first surrounding portion;

[0031] Figure 6 is a top view showing the structure of the second surrounding portion;

[0032] Figure 7 is a top view showing the suction stroke of the screw compressor;

[0033] Figure 8 is a top view showing the compression stroke of the screw compressor;

[0034] Fig. 9 is a top view showing the exhaust stroke of the screw compressor;

[0035] Fig.10 is an expanded view of the screw rotor and the partition wall portion, showing a state before the first compression chamber and the second compression chamber are completely closed;

[0036] Fig.11 is an expanded view of the screw rotor and the partition wall portion, showing a state in which the first compression chamber and the second compression chamber are completely closed;

[0037] Fig.12 is a plan view showing the structure of a second surrounding portion in the screw compressor according to the second embodiment;

[0038] Fig.13 is a plan view showing the structure of a second surrounding portion in a screw compressor according to a third embodiment;

[0039] Fig.14 is a cross-sectional view showing the structure of a screw compressor according to a fourth embodiment;

[0040] Fig.15 is a top view showing the structure of the first surrounding portion;

[0041] Fig.16 It is a top view showing the structure of the second surrounding part. DETAILED DESCRIPTION

[0042] (First Embodiment)

[0043] like Figure 1As shown, a screw compressor 1 is provided in a refrigeration device 2. The refrigeration device 2 has a refrigerant circuit 2a filled with refrigerant. The refrigerant circuit 2a has a screw compressor 1, a radiator 3, a decompression mechanism 4, and an evaporator 5. The decompression mechanism 4 is, for example, an expansion valve. The refrigerant circuit 2a performs a vapor compression refrigeration cycle.

[0044] The refrigeration device 2 is an air conditioning device. The air conditioning device may be a dedicated refrigeration device, a dedicated heating device, or an air conditioning device that switches between refrigeration and heating. In this case, the air conditioning device has a switching mechanism (such as a four-way reversing valve) that switches the circulation direction of the refrigerant. The refrigeration device 2 may also be a water heater, a cooling unit, a cooling device that cools the air in the warehouse, etc. The cooling device cools the air inside a cold storage, a freezer, a container, etc.

[0045] like Figure 2 and Figure 3 As shown, the screw compressor 1 includes a housing 10 and a compression mechanism 20. The compression mechanism 20 is accommodated in the housing 10. The compression mechanism 20 is connected to a motor (not shown) via a drive shaft 25.

[0046] The shell 10 includes a low-pressure space S1 into which a low-pressure refrigerant flows, an intermediate-pressure space S2 into which an intermediate-pressure refrigerant having a higher pressure than the low-pressure refrigerant flows, and a high-pressure space S3 into which a refrigerant having a higher pressure than the intermediate-pressure refrigerant flows.

[0047] The compression mechanism (20) includes a partition wall portion (15) provided in the casing (10), one screw rotor (40), a first rotor (31), and a second rotor (32).

[0048] The partition wall portion 15 is formed in a cylindrical shape. The screw rotor 40 is attached to the partition wall portion 15. The partition wall portion 15 covers the outer peripheral surface of the screw rotor 40. The first rotor 31 and the second rotor 32 penetrate the partition wall portion 15 and mesh with the screw rotor 40.

[0049] The screw rotor (40) is a metal member formed in a substantially cylindrical shape. The outer diameter of the screw rotor (40) is set to be slightly smaller than the inner diameter of the partition wall portion (15). The outer peripheral surface of the screw rotor (40) is close to the inner peripheral surface of the partition wall portion (15).

[0050] A plurality of spiral grooves 41 extending in a spiral shape are formed on the outer periphery of the screw rotor 40. The spiral grooves 41 extend from one axial end of the screw rotor 40 toward the other end. A first end 42 and a second end 43 are provided at both axial ends of the screw rotor 40. The first end 42 and the second end 43 each have a smooth cylindrical outer peripheral surface on which the spiral grooves 41 are not formed. The spiral grooves 41 of the screw rotor 40 are formed between the first end 42 and the second end 43 of the screw rotor 40. The drive shaft 25 is connected to the screw rotor 40. The drive shaft 25 and the screw rotor 40 rotate integrally.

[0051] like Figure 2 As shown, the first rotor 31 is composed of a first gate rotor 50. The first gate rotor 50 has a plurality of teeth, namely, first gates 51, arranged radially. The first gates 51 mesh with the spiral grooves 41 of the screw rotor 40. The first gate rotor 50 is accommodated in a first gate rotor chamber 17. The first gate rotor chamber 17 is formed by partitioning in the casing 10, and the first gate rotor chamber 17 is adjacent to the partition wall portion 15.

[0052] The second rotor 32 is composed of a second gate rotor 60. The second gate rotor 60 has a plurality of teeth, namely, second gates 61, which are arranged radially. The second gates 61 mesh with the spiral grooves 41 of the screw rotor 40. The second gate rotor 60 is accommodated in a second gate rotor chamber 18. The second gate rotor chamber 18 is formed by partitioning the inside of the casing 10, and the second gate rotor chamber 18 is adjacent to the partition wall portion 15.

[0053] In the compression mechanism (20), a space surrounded by the inner peripheral surface of a first surrounding portion (11) (described later) of the partition wall (15), the spiral groove (41) of the screw rotor (40), and the first gate (51) of the first gate rotor (50) defines a first compression chamber (21).

[0054] In the compression mechanism (20), a space surrounded by the inner peripheral surface of a second surrounding portion (12) described later in the partition wall (15), the spiral groove (41) of the screw rotor (40), and the second gate (61) of the second gate rotor (60) defines a second compression chamber (22).

[0055] A bearing housing 52 is provided in the first gate rotor chamber 17. The bearing housing 52 has a ball bearing 53. The first rotating shaft 55 of the first gate rotor 50 is rotatably supported via the ball bearing 53.

[0056] A bearing housing 52 is provided in the second gate rotor chamber 18. The bearing housing 52 has a ball bearing 53. The second rotating shaft 65 of the second gate rotor 60 is rotatably supported via the ball bearing 53.

[0057] The first rotating shaft (55) of the first gate rotor (50) and the second rotating shaft (65) of the second gate rotor (60) are substantially perpendicular to a virtual plane F extending along the drive shaft (25) of the screw rotor (40) (see FIG. Figure 2 Specifically, the first gate 51 of the first gate rotor 50 and the second gate 61 of the second gate rotor 60 are arranged on the same imaginary plane F.

[0058] Thus, when the housing 10 is processed by a machine tool (not shown), it is not necessary to perform a switching process for temporarily removing the housing 10 held on the machine tool and adjusting the holding state, thereby improving working efficiency.

[0059] Specifically, a rotating tool (not shown) of a machine tool is moved from Figure 2 The case where the front side of the paper moves toward the back side of the paper toward the casing 10 is studied. In this case, after the hole for the screw rotor 40 is formed in the casing 10 using a rotating tool, the casing 10 is held on a holding table (not shown) of a machine tool, and the holding table is rotated 90 degrees toward the front side. As a result, the first rotating shaft 55 of the first gate rotor 50 and the second rotating shaft 65 of the second gate rotor 60 are moved toward the front side. Figure 2 Therefore, the holding form of the housing 10 is not changed, and only the rotating tool is moved from Figure 2 By moving the front side of the paper toward the back side of the paper, the holes for the first gate rotor 50 and the second gate rotor 60 can be processed separately. As a result, the processing accuracy of the housing 10 can be ensured.

[0060] 〈Slide valve〉

[0061] like Figure 3 As shown, the screw compressor 1 is provided with a slide valve 27. The slide valve 27 is housed in a valve housing portion 16 formed by bulging the partition wall portion 15 radially outward at two locations in the circumferential direction (see Figure 2 ).

[0062] The slide valve 27 is configured to be slidable along the axial direction of the partition wall portion 15. The slide valve 27 faces the outer peripheral surface of the screw rotor 40 when inserted into the valve housing portion 16. The screw compressor 1 is provided with a drive mechanism 28 for driving the slide valve 27 to slide.

[0063] The slide valve 27 is a valve capable of adjusting the position in the axial direction of the screw rotor 40. The slide valve 27 can be used as an unloading mechanism that returns the refrigerant in the compression process in the first compression chamber 21 or the second compression chamber 22 to the suction side to change the operating capacity. The slide valve 27 can be used as a compression ratio adjustment mechanism that adjusts the compression ratio (internal volume ratio) by adjusting the timing of the refrigerant being discharged from the first compression chamber 21 or the second compression chamber 22.

[0064] Fixed discharge ports (not shown) are formed in the partition wall portion 15 , respectively. The fixed discharge ports are always in communication with the first compression chamber 21 and the second compression chamber 22 regardless of the position of the slide valve 27 .

[0065] 〈First compression chamber and second compression chamber〉

[0066] The first compression chamber 21 is a compression chamber on the low-stage side of the two-stage compression, and compresses the refrigerant at the suction pressure introduced into the shell 10 to an intermediate pressure higher than the suction pressure. The second compression chamber 22 is a compression chamber on the high-stage side of the two-stage compression, and compresses the refrigerant at the intermediate pressure to a discharge pressure higher than the intermediate pressure.

[0067] The shell 10 is provided with: a low-pressure space S1 communicating with the suction side of the first compression chamber 21, a medium-pressure space S2 communicating with the discharge side of the first compression chamber 21 and the suction side of the second compression chamber 22, and a high-pressure space S3 communicating with the discharge side of the second compression chamber 22.

[0068] Specifically, the low-pressure pipe 6 through which the low-pressure refrigerant flows is connected to the first gate rotor chamber 17. The first gate rotor chamber 17 becomes a low-pressure space S1 by supplying the low-pressure refrigerant from the low-pressure pipe 6 to the first gate rotor chamber 17. The first gate rotor chamber 17 is configured to supply the low-pressure refrigerant to the suction opening of the first compression chamber 21. The low-pressure refrigerant is compressed in the first compression chamber 21 to become a medium-pressure refrigerant.

[0069] The intermediate-pressure refrigerant compressed to an intermediate pressure in the first compression chamber 21 is supplied to the second gate rotor chamber 18 via a space where a motor (not shown) is arranged. The supply of the intermediate-pressure refrigerant to the second gate rotor chamber 18 turns the second gate rotor chamber 18 into an intermediate-pressure space S2.

[0070] A notch 13 (see also FIG. 1 ) is provided at the axial end of the partition wall 15 on the medium pressure space S2 side. Figure 4 ). The notch 13 is formed by cutting off a portion of the partition wall 15. The intermediate pressure space S2 and the second compression chamber 22 are connected through the notch 13. An oil film is formed between the first end 42 of the screw rotor 40 and the partition wall 15. Thus, the refrigerant is prevented from flowing between the partition wall 15 and the first compression chamber 21 of the screw rotor 40.

[0071] The intermediate-pressure refrigerant flowing in the intermediate-pressure space S2 is supplied to the suction opening of the second compression chamber 22 through the notch 13 of the partition wall 15. The intermediate-pressure refrigerant is compressed in the second compression chamber 22 to become a high-pressure refrigerant.

[0072] The high-pressure refrigerant compressed in the second compression chamber 22 to a high pressure is supplied to the high-pressure space S3. The high-pressure refrigerant flowing in the high-pressure space S3 is discharged from a discharge port (not shown) of the shell 10.

[0073] In this way, the low-pressure space S1, the first compression chamber 21, the medium-pressure space S2, the second compression chamber 22 and the high-pressure space S3 are connected in sequence from the side with low fluid pressure to the side with high fluid pressure.

[0074] <First surrounding part and second surrounding part>

[0075] like Figure 5 and Figure 6As shown, the partition wall portion 15 includes a first surrounding portion 11 and a second surrounding portion 12. The first surrounding portion 11 is configured to disconnect the first compression chamber 21 from the low-pressure space S1 on the outer peripheral side thereof before the first compression chamber 21 reaches the suction closed position where the first gate rotor 50 completely closes the first compression chamber 21 during the rotation of the screw rotor 40.

[0076] The edge of the first surrounding portion 11 is shaped to draw a curve parallel to the edge of the circumferential sealing surface 44 of the screw rotor 40. In other words, the edge of the first surrounding portion 11 is shaped to overlap the circumferential sealing surface 44 that moves as the screw rotor 40 rotates over its entire length.

[0077] The second surrounding portion (12) is configured to isolate the second compression chamber (22) from the intermediate-pressure space (S2) on the outer peripheral side thereof before the second compression chamber (22) reaches a suction closed position at which the second compression chamber (22) is completely closed by the second gate rotor (60) during the rotation of the screw rotor (40).

[0078] The edge of the second surrounding portion 12 is shaped to draw a curve parallel to the edge of the circumferential sealing surface 44 of the screw rotor 40. In other words, the edge of the second surrounding portion 12 is shaped to overlap the circumferential sealing surface 44 that moves as the screw rotor 40 rotates over its entire length.

[0079] In the present embodiment, the axial length D1 of the first surrounding portion 11 extending along the drive shaft 25 of the screw rotor 40 is different from the axial length D2 of the second surrounding portion 12 extending along the drive shaft 25. Specifically, the axial length D1 of the first surrounding portion 11 is longer than the axial length D2 of the second surrounding portion 12.

[0080] Thus, the first compression chamber 21 is completely closed by the first gate rotor 50 earlier than the second compression chamber 22 is completely closed by the second gate rotor 60. As a result, the volume of the first compression chamber 21 is larger than the volume of the second compression chamber 22. Here, the axial length D1 of the first surrounding portion 11 and the axial length D2 of the second surrounding portion 12 are preferably set so that the volume of the first compression chamber 21 is approximately two to three times the volume of the second compression chamber 22.

[0081] In this way, by changing the full closing timing of the first compression chamber 21 and the full closing timing of the second compression chamber 22, the volume ratio between the first compression chamber 21 and the second compression chamber 22 can be appropriately set.

[0082] - Operation -

[0083] <Intake, compression and exhaust stroke>

[0084] When the screw rotor (40) rotates, the first gate rotor (50) and the second gate rotor (60) that mesh with the spiral groove (41) rotate. Thus, in the compression mechanism (20), the suction stroke, the compression stroke, and the exhaust stroke are continuously and repeatedly performed.

[0085] exist Figure 7 In the suction stroke shown, the shaded first compression chamber 21 is connected to the suction side space. The spiral groove 41 corresponding to the first compression chamber 21 meshes with the first gate 51 of the first gate rotor 50. When the screw rotor 40 rotates, the first gate 51 moves relatively toward the terminal end of the spiral groove 41, and the volume of the first compression chamber 21 expands accordingly. As a result, the refrigerant is sucked into the first compression chamber 21.

[0086] As the screw rotor 40 further rotates, Figure 8 The compression stroke shown. During the compression stroke, the shaded first compression chamber 21 is in a completely closed state. That is, the spiral groove 41 corresponding to the first compression chamber 21 is separated from the suction side space by the first gate 51. When the first gate 51 approaches the terminal end of the spiral groove 41 as the screw rotor 40 rotates, the volume of the first compression chamber 21 gradually decreases. As a result, the refrigerant in the first compression chamber 21 is compressed.

[0087] As the screw rotor 40 further rotates, Fig. 9 In the exhaust stroke, the shaded first compression chamber 21 is connected to the fixed discharge port via the discharge side end (the right end in the figure). When the first gate 51 approaches the terminal end of the spiral groove 41 as the screw rotor 40 rotates, the compressed refrigerant is pushed from the first compression chamber 21 to the discharge side space through the fixed discharge port.

[0088] It should be noted that the intake stroke, the compression stroke, and the exhaust stroke in the second compression chamber 22 on the high-stage side are also the same as the strokes in the first compression chamber 21 on the low-stage side, and therefore their description is omitted.

[0089] 〈About the time of complete closure〉

[0090] Hereinafter, the difference between the fully closed timing of the first compression chamber 21 and the fully closed timing of the second compression chamber 22 will be described.

[0091] like Fig.10 As shown, the focus is on a spiral groove 41 formed in the first compression chamber 21 in the suction stroke. A portion of the spiral groove 41 is covered by the first enclosure 11, and the remaining portion of the spiral groove 41 is in a state of facing the low-pressure space S1. The first gate 51 enters the spiral groove 41 from the starting end side of the spiral groove 41. Fig.10In the illustrated state, the first compression chamber 21 formed by the spiral groove 41 in the suction stroke communicates with the low-pressure space S1 on the outer peripheral surface of the screw rotor 40. In this state, low-pressure refrigerant flows into the first compression chamber 21 from the outer peripheral surface of the screw rotor 40.

[0092] When the screw rotor 40 is Fig.10 When the state shown starts to rotate, it becomes Fig.11 The status shown. Fig.11 In the illustrated state, the first gate 51 entering the spiral groove 41 is in sliding contact with the groove wall and the groove bottom of the spiral groove 41. The sealing surface 44 of the screw rotor 40 in the circumferential direction overlaps with the first surrounding portion 11.

[0093] Thus, the first compression chamber 21 becomes a closed space separated from the low-pressure space S1 by both the first surrounding portion 11 and the first gate 51, and the suction stroke ends (referred to herein as a suction closed position).

[0094] Thus, with respect to the first compression chamber 21 in the suction stroke, the spiral groove 41 moves from the position facing the low-pressure space S1 to the position covered by the first enclosure 11, thereby being separated from the low-pressure space S1, and at the same time, the first gate 51 separates the spiral groove 41 from the low-pressure space S1. In the screw compressor 1, the shape of the first enclosure 11 is set so that the refrigerant in the first compression chamber 21 flows to the low-pressure space S1 before reaching the suction closed position.

[0095] The second compression chamber 22 is also similarly Fig.11 At the time of the state shown, the second compression chamber 22 becomes a closed space separated from the medium-pressure space S2 by the second surrounding portion 12 and the second gate 61, and the suction stroke is completed.

[0096] Thus, with respect to the second compression chamber 22 in the suction stroke, the spiral groove 41 moves from the position facing the intermediate pressure space S2 to the position covered by the second enclosure 12, thereby being separated from the intermediate pressure space S2, and at the same time, the second gate 61 separates the spiral groove 41 from the intermediate pressure space S2. In the screw compressor 1, the shape of the second enclosure 12 is set so that the refrigerant in the second compression chamber 22 flows to the intermediate pressure space S2 before reaching the suction closing position.

[0097] Here, the axial length D1 of the first surrounding portion 11 is longer than the axial length D2 of the second surrounding portion 12. Therefore, the first compression chamber 21 is fully closed earlier than the second compression chamber 22.

[0098] - Effects of the First Embodiment -

[0099] According to the characteristics of this embodiment, the axial length D1 of the first surrounding portion 11 is different from the axial length D2 of the second surrounding portion 12. Thus, by changing the fully closed timing of the first compression chamber 21 and the fully closed timing of the second compression chamber 22, the volume ratio of the first compression chamber 21 to the second compression chamber 22 can be appropriately set.

[0100] According to the features of this embodiment, in the screw compressor including the single screw rotor (40), the first gate rotor (50), and the second gate rotor (60), the volume ratio between the first compression chamber (21) and the second compression chamber (22) can be appropriately set.

[0101] According to the characteristics of this embodiment, the first rotating shaft 55 of the first gate rotor 50 and the second rotating shaft 65 of the second gate rotor 60 are substantially orthogonal to the imaginary plane F extending along the drive shaft 25 of the screw rotor 40. Thus, without changing the holding form of the casing 10, the holes for supporting the rotating shafts of the screw rotor 40, the first gate rotor 50, and the second gate rotor 60 can be machined while the rotating tool of the machine tool is relatively moved in one direction, thereby ensuring the machining accuracy of the casing 10.

[0102] According to the features of this embodiment, the screw compressor 1 and the refrigerant circuit 2a in which the refrigerant compressed by the screw compressor 1 flows are provided. Thus, the refrigeration device 2 including the screw compressor 1 can be provided.

[0103] (Second Embodiment)

[0104] Hereinafter, the same reference numerals are used to denote the same components as those in the first embodiment, and only the different points will be described.

[0105] exist Fig.12 In the example shown, the axial length D2 of the second surrounding portion 12 is set to be equal to the axial length D1 of the first surrounding portion 11 (see Figure 5 ) of the same length.

[0106] The second enclosure 12 is provided with an opening 35 extending from the inner surface to the outer surface of the second enclosure 12. The opening 35 is a through hole 36 formed in the second enclosure 12. The through hole 36 is formed at the edge of the second enclosure 12 near the second gate rotor 60.

[0107] Here, in the second compression chamber 22 in the suction stroke, even if the spiral groove 41 moves from the position facing the intermediate pressure space S2 to the position covered by the edge of the second enclosure 12, the refrigerant flows from the through hole 36 to the intermediate pressure space S2. Fig.12When the sealing surface 44 of the spiral groove 41 (in the middle upper position) is covered, the second compression chamber 22 is in a completely closed state.

[0108] Thus, by forming the through hole 36 in the second enclosure 12, the time when the second compression chamber 22 is completely closed by the second gate rotor 60 is later than the time when the first compression chamber 21 is completely closed by the first gate rotor 50. As a result, the volume of the first compression chamber 21 is larger than the volume of the second compression chamber 22. Here, it is preferable that the position of the through hole 36 in the second enclosure 12 is set so that the volume of the first compression chamber 21 is approximately two to three times the volume of the second compression chamber 22.

[0109] - Effects of the Second Embodiment -

[0110] According to the feature of this embodiment, the opening 35 is provided in the second surrounding portion 12. Thus, by changing the full closing timing of the first compression chamber 21 and the full closing timing of the second compression chamber 22, the volume ratio of the first compression chamber 21 and the second compression chamber 22 can be appropriately set.

[0111] According to the feature of this embodiment, the opening 35 is a through hole 36 formed in the second surrounding portion 12. By forming the through hole 36 in the second surrounding portion 12, the volume ratio between the first compression chamber 21 and the second compression chamber 22 can be appropriately set.

[0112] (Third Embodiment)

[0113] exist Fig.13 In the example shown, the axial length D2 of the second surrounding portion 12 is set to be equal to the axial length D1 of the first surrounding portion 11 (see Figure 5 ) of the same length.

[0114] The second enclosure 12 is provided with an opening 35 extending from the inner surface to the outer surface of the second enclosure 12. The opening 35 is a notch 37 formed at the edge of the second enclosure 12. The notch 37 is formed at the edge of the second enclosure 12 and extends in the circumferential direction at a position close to the second gate rotor 60.

[0115] Here, in the second compression chamber 22 in the suction stroke, even if the spiral groove 41 moves from the position facing the intermediate pressure space S2 to the position covered by the second surrounding portion 12, the refrigerant flows from the notch portion 37 to the intermediate pressure space S2. Fig.13 When the spiral groove 41 is covered, the second compression chamber 22 is in a completely closed state.

[0116] Thus, by forming the notch 37 in the second enclosure 12, the time when the second compression chamber 22 is completely closed by the second gate rotor 60 is later than the time when the first compression chamber 21 is completely closed by the first gate rotor 50. As a result, the volume of the first compression chamber 21 is larger than the volume of the second compression chamber 22. Here, it is preferable that the position of the notch 37 in the second enclosure 12 is set so that the volume of the first compression chamber 21 is approximately two to three times the volume of the second compression chamber 22.

[0117] - Effects of the Third Embodiment -

[0118] According to the feature of this embodiment, the opening 35 is a notch 37 formed at the edge of the second surrounding portion 12. By forming the notch 37 at the edge of the second surrounding portion 12, the volume ratio of the first compression chamber 21 to the second compression chamber 22 can be appropriately set.

[0119] (Fourth Embodiment)

[0120] like Figure 14 to Figure 16 As shown, the screw compressor 1 includes a housing 10 and a compression mechanism 20. The compression mechanism 20 is accommodated in the housing 10. The compression mechanism 20 is connected to a motor 26 via a drive shaft 25.

[0121] The compression mechanism 20 includes a partition wall portion 15 provided in the housing 10, a screw rotor 40, a first rotor 31, and a second rotor 32. The first rotor 31 is composed of a first female rotor 70 having a plurality of first spiral grooves 71. The second rotor 32 is composed of a second female rotor 80 having a plurality of second spiral grooves 81. The screw rotor 40 is composed of a male rotor meshing with the first female rotor 70 and the second female rotor 80. The screw compressor 1 of the present embodiment is a so-called three-rotor type compressor.

[0122] The screw rotor 40, the first female rotor 70, and the second female rotor 80 are mounted on the partition wall portion 15. The partition wall portion 15 covers the outer peripheral surfaces of the screw rotor 40, the first female rotor 70, and the second female rotor 80. The first female rotor 70 and the second female rotor 80 mesh with the screw rotor 40. The drive shaft 25 of the screw rotor 40 is supported by the bearing 73 so as to be able to rotate freely. The first rotating shaft 75 of the first female rotor 70 is supported by the bearing 73 so as to be able to rotate freely. The second rotating shaft 85 of the second female rotor 80 is supported by the bearing 73 so as to be able to rotate freely.

[0123] like Fig.15 and Fig.16As shown, the partition wall portion 15 has a first surrounding portion 11 and a second surrounding portion 12. In the compression mechanism 20, a space surrounded by the inner peripheral surface of the first surrounding portion 11, the spiral groove 41 of the screw rotor 40, the groove wall of the first spiral groove 71 of the first female rotor 70, and the groove wall of the second spiral groove 81 of the second female rotor 80 becomes the first compression chamber 21. In the compression mechanism 20, a space surrounded by the inner peripheral surface of the second surrounding portion 12, the spiral groove 41 of the screw rotor 40, the groove wall of the first spiral groove 71 of the first female rotor 70, and the groove wall of the second spiral groove 81 of the second female rotor 80 becomes the second compression chamber 22.

[0124] The first compression chamber 21 is a compression chamber on the low-stage side of the two-stage compression, and compresses the refrigerant at the suction pressure introduced into the shell 10 to an intermediate pressure higher than the suction pressure. The second compression chamber 22 is a compression chamber on the high-stage side of the two-stage compression, and compresses the refrigerant at the intermediate pressure to a discharge pressure higher than the intermediate pressure.

[0125] The shell 10 is provided with: a low-pressure space S1 communicating with the suction side of the first compression chamber 21, a medium-pressure space S2 communicating with the discharge side of the first compression chamber 21 and the suction side of the second compression chamber 22, and a high-pressure space S3 communicating with the discharge side of the second compression chamber 22.

[0126] In this way, the low-pressure space S1, the first compression chamber 21, the medium-pressure space S2, the second compression chamber 22 and the high-pressure space S3 are connected in sequence from the side with low fluid pressure to the side with high fluid pressure.

[0127] The first surrounding portion 11 is configured to isolate the first compression chamber 21 from the low-pressure space S1 on the outer peripheral side thereof before reaching a suction closed position where the first compression chamber 21 is completely closed by the first female rotor 70 and the second female rotor 80 during the rotation of the screw rotor 40 .

[0128] The edge of the first surrounding portion 11 is shaped to draw a curve parallel to the edge of the circumferential sealing surface 44 of the screw rotor 40. In other words, the edge of the first surrounding portion 11 is shaped to overlap the circumferential sealing surface 44 that moves as the screw rotor 40 rotates over its entire length.

[0129] The second surrounding portion 12 is configured to isolate the second compression chamber 22 from the intermediate-pressure space S2 on the outer peripheral side thereof before reaching the suction closed position where the second compression chamber 22 is completely closed by the first female rotor 70 and the second female rotor 80 during the rotation of the screw rotor 40 .

[0130] The edge of the second surrounding portion 12 is shaped to draw a curve parallel to the edge of the circumferential sealing surface 44 of the screw rotor 40. In other words, the edge of the second surrounding portion 12 is shaped to overlap the circumferential sealing surface 44 that moves as the screw rotor 40 rotates over its entire length.

[0131] In the present embodiment, the axial length D1 of the first surrounding portion 11 extending along the drive shaft 25 of the screw rotor 40 is different from the axial length D2 of the second surrounding portion 12 extending along the drive shaft 25. Specifically, the axial length D1 of the first surrounding portion 11 is longer than the axial length D2 of the second surrounding portion 12.

[0132] Thus, the first compression chamber 21 is completely closed by the first female rotor 70 and the second female rotor 80 earlier than the second compression chamber 22 is completely closed by the first female rotor 70 and the second female rotor 80. As a result, the volume of the first compression chamber 21 is larger than the volume of the second compression chamber 22. Here, it is preferable to set the axial length D1 of the first enclosure 11 and the axial length D2 of the second enclosure 12 so that the volume of the first compression chamber 21 is approximately two to three times the volume of the second compression chamber 22.

[0133] In this way, by changing the full closing timing of the first compression chamber 21 and the full closing timing of the second compression chamber 22, the volume ratio between the first compression chamber 21 and the second compression chamber 22 can be appropriately set.

[0134] - Effects of the Fourth Embodiment -

[0135] According to the features of this embodiment, in the screw compressor 1 including the one screw rotor 40 (male rotor), the first female rotor 70 and the second female rotor 80, the volume ratio between the first compression chamber 21 and the second compression chamber 22 can be appropriately set.

[0136] (Other embodiments)

[0137] The above-described embodiment may also adopt the following structure.

[0138] The structure and shape of the first gate rotor (50) and the ratio of the number of grooves of the screw rotor (40) to the number of teeth of the first gate rotor (50) described in the above embodiment are not limited to the above embodiment and may be changed.

[0139] In the above embodiment, in the three-rotor screw compressor 1, the fully closed timing is changed by setting the axial length D1 of the first surrounding portion 11 and the axial length D2 of the second surrounding portion 12 to different lengths, but the present invention is not limited to this.

[0140] For example, the axial length D1 of the first surrounding portion 11 and the axial length D2 of the second surrounding portion 12 may be set to be the same length, and a through hole 36 serving as the opening 35 may be formed in the second surrounding portion 12 (see Fig.12 )、Notch 37 (refer to Fig.13 ), thereby changing the fully closed time.

[0141] The above describes the implementation and variants, but it should be understood that various changes can be made to their forms and specific matters without departing from the subject matter and scope of the claims. It is also possible to appropriately combine or replace the elements involved in the above implementation, variants, and other implementations. The words "first", "second", "third"... in the specification and claims are only used to distinguish sentences containing the above words, and are not intended to limit the number or order of the sentences.

[0142] - Industrial Applicability -

[0143] In summary, the present disclosure is useful for screw compressors and refrigeration devices.

[0144] - Explanation of symbols -

[0145] 1 screw compressor

[0146] 2 Refrigeration unit

[0147] 2a Refrigerant circuit

[0148] 10 Shell

[0149] 11 First enclosure

[0150] 12 Second surrounding part

[0151] 15 partition wall

[0152] 21First compression chamber

[0153] 22 Second compression chamber

[0154] 25 drive shaft

[0155] 31First rotor

[0156] 32 Second rotor

[0157] 35 Opening

[0158] 36 through holes

[0159] 37 Notch

[0160] 40 screw rotor

[0161] 41 spiral groove

[0162] 50First gate rotor

[0163] 51 First Gate

[0164] 55First rotation axis

[0165] 60 Second gate rotor

[0166] 61 Second Gate

[0167] 65 Second rotation axis

[0168] 70 First female rotor

[0169] 71 First spiral groove

[0170] 80 Second female rotor

[0171] 81 Second spiral groove

[0172] D1 axial length

[0173] D2 axial length

[0174] F imaginary plane

Claims

1. A screw compressor, comprising a screw rotor (40), a first rotor (31), a second rotor (32) and a casing (10), wherein the screw rotor (40) has a plurality of spiral grooves (41), the first rotor (31) meshes with the spiral grooves (41) of the screw rotor (40), and the second rotor (32) meshes with the spiral grooves (41) of the screw rotor (40), and the casing (10) has a partition wall portion (15), the screw rotor (40) is rotatably held by the partition wall portion (15), and the partition wall portion (15) covers the outer peripheral surface of the screw rotor (40), characterized in that: The partition wall portion (15) includes a first surrounding portion (11) for forming a first compression chamber (21) and a second surrounding portion (12) for forming a second compression chamber (22). The first compression chamber (21) is formed inside the first surrounding portion (11) by the screw rotor (40) and the first rotor (31). The first compression chamber (21) compresses the fluid at the suction pressure introduced into the casing (10) to an intermediate pressure higher than the suction pressure. The second compression chamber (22) is formed inside the second surrounding portion (12) by the screw rotor (40) and the second rotor (32), and the second compression chamber (22) compresses the fluid at the intermediate pressure to a discharge pressure higher than the intermediate pressure. The axial length (D1) of the first surrounding portion (11) extending along the drive shaft (25) of the screw rotor (40) is different from the axial length (D2) of the second surrounding portion (12) extending along the drive shaft (25). An axial length (D1) of the first surrounding portion (11) is longer than an axial length (D2) of the second surrounding portion (12).

2. A screw compressor, comprising a screw rotor (40), a first rotor (31), a second rotor (32) and a casing (10), wherein the screw rotor (40) has a plurality of spiral grooves (41), the first rotor (31) meshes with the spiral grooves (41) of the screw rotor (40), and the second rotor (32) meshes with the spiral grooves (41) of the screw rotor (40), and the casing (10) has a partition wall portion (15), the screw rotor (40) is rotatably held by the partition wall portion (15), and the partition wall portion (15) covers the outer peripheral surface of the screw rotor (40), characterized in that: The partition wall portion (15) includes a first surrounding portion (11) for forming a first compression chamber (21) and a second surrounding portion (12) for forming a second compression chamber (22). The first compression chamber (21) is formed inside the first surrounding portion (11) by the screw rotor (40) and the first rotor (31). The first compression chamber (21) compresses the fluid at the suction pressure introduced into the casing (10) to an intermediate pressure higher than the suction pressure. The second compression chamber (22) is formed inside the second surrounding portion (12) by the screw rotor (40) and the second rotor (32), and the second compression chamber (22) compresses the fluid at the intermediate pressure to a discharge pressure higher than the intermediate pressure. The second enclosure (12) is provided with an opening (35) extending from the inner surface to the outer surface of the second enclosure (12), so that the second compression chamber (22) is completely closed by the second rotor (32) later than the first compression chamber (21) is completely closed by the first rotor (31).

3. The screw compressor according to claim 2, characterized in that: The opening portion (35) is a through hole (36) formed in the second surrounding portion (12).

4. The screw compressor according to claim 2, characterized in that: The opening portion (35) is a notch portion (37) formed at the edge of the second surrounding portion (12).

5. The screw compressor according to any one of claims 1 to 4, characterized in that: The first rotor (31) is composed of a first gate rotor (50) having a plurality of first gates (51) arranged radially. The second rotor (32) is composed of a second gate rotor (60) having a plurality of second gates (61) arranged radially. The first gate (51) and the second gate (61) are respectively engaged with the spiral groove (41) of one of the screw rotors (40).

6. The screw compressor according to claim 5, characterized in that: A first rotation axis (55) of the first gate rotor (50) and a second rotation axis (65) of the second gate rotor (60) are orthogonal to an imaginary plane (F) extending along a drive axis (25) of the screw rotor (40).

7. The screw compressor according to any one of claims 1 to 4, characterized in that: The first rotor (31) is composed of a first female rotor (70) having a plurality of first spiral grooves (71). The second rotor (32) is composed of a second female rotor (80) having a plurality of second spiral grooves (81). The screw rotor (40) is composed of a male rotor meshing with the first female rotor (70) and the second female rotor (80).

8. A refrigeration device, characterized in that: The refrigeration device comprises the screw compressor (1) according to any one of claims 1 to 4, and a refrigerant circuit (2a) through which the refrigerant compressed by the screw compressor (1) flows.

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