Screw Compressor

Abstract

To suppress fluid pressure loss in a screw compressor.SOLUTION: A screw compressor (1) comprises a screw rotor (20), a gate rotor (30, 35), and a casing (50). The screw rotor, the gate rotor and the casing (50) form a compression chamber (S1, S2) that compresses fluid (W). A case-side discharge port (63, 64) is formed in a case outer wall part (58) on an outer periphery side (Ra) in a radial direction (R) of the casing (50). A discharge port (65, 66) is formed in a portion (55c, 55d) of the casing (50) facing the compression chamber. The discharge port includes a front end part (65a, 66a) on a front side (Xa) in an axial direction (X), and a rear end part (65b, 66b) on a rear side (Xb) in the axial direction (X). The case-side discharge port is located in the axial direction (X) between a front position (Ka) that is away from the front end part to the front side by a gate radius (r), and a rear position (Kb) that is away from the second end part to the rear side by a gate radius (r).SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present disclosure relates to screw compressors. [Background technology]

[0002] For example, as disclosed in Patent Document 1, various techniques have been disclosed regarding screw compressors. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-025435 A Summary of the Invention [Problem to be solved by the invention]

[0004] This type of screw compressor includes a screw rotor, a gate rotor, and a casing. The screw rotor extends in the axial direction, and has a screw groove on its outer periphery. The gate rotor is provided with a gate. The gate of the gate rotor meshes with the screw groove of the screw rotor. The casing rotatably holds the screw rotor, and covers the screw rotor from the outer periphery.

[0005] The screw rotor, the gate rotor, and the casing form a compression chamber for compressing a fluid. A discharge port is formed in a portion of the casing facing the compression chamber. The discharge port is located on the outer periphery side of the compression chamber. A discharge cover is attached to one axial side of the casing. The discharge cover is provided with a discharge port.

[0006] In the screw compressor disclosed in Patent Document 1, since a discharge cover is interposed between the discharge port and the discharge port, the discharge port and the discharge port are necessarily separated from each other in the axial direction. Therefore, the fluid compressed in the compression chamber flows from the compression chamber toward the discharge port toward the outer periphery, then changes direction to the axial direction, flows in the casing in the axial direction, reaches the discharge cover, and is discharged outside the discharge cover through the discharge port.

[0007] In the screw compressor disclosed in Patent Document 1, the fluid is forced to change direction from radial to axial midway through the flow path from the discharge port to the discharge outlet, which causes a pressure loss until the fluid compressed in the compression chamber is discharged to the outside through the discharge port and the discharge outlet.

[0008] An object of the present disclosure is to reduce fluid pressure loss in a screw compressor. [Means for solving the problem]

[0009] A first aspect of the present disclosure is directed to a screw compressor (1). The screw compressor (1) includes a screw rotor (20) having a screw groove (21) and extending in an axial direction (X), a gate rotor (30, 35) having a gate (32, 37) meshing with the screw groove (21), and a casing (50) that rotatably holds the screw rotor (20) and covers the screw rotor (20) from the outside (Ra) in a radial direction (R) perpendicular to the axial direction (X). The rotor (20), the gate rotor (30, 35), and the casing (50) form compression chambers (S1, S2) for compressing a fluid (W). A case outer wall portion (58) on the outer side (Ra) in the radial direction (R) of the casing (50) is formed with case side discharge ports (63, 64) from which the fluid (W) is discharged. The case-side discharge port (63, 64) is formed with a discharge port (65, 66) communicating with a case-side discharge port (63, 64), the discharge port (65, 66) includes a first end portion (65a, 66a) on a first direction side (Xa) in the axial direction (X) and a second end portion (65b, 66b) on a second direction side (Xb) opposite to the first direction side (Xa) in the axial direction (X), and the case-side discharge port (63, 64) is formed with a discharge port (65, 66) communicating with a case-side discharge port (63, 64) in the axial direction (X), the discharge port (65, 66) includes a first end portion (65a, 66a) on a first direction side (Xa) in the axial direction (X) and a second end portion (65b, 66b) on a second direction side (Xb) opposite to the first direction side (Xa) in the axial direction (X). ) in the first direction (Xa) by the radius (r) of the gate (32, 37), and a second position (Kb) in the second direction (Xb) by the radius (r) of the gate (32, 37) from the second end (65b, 66b), and the case side discharge port (63, 64) is located on a side closer to the discharge port (65, 66) than the screw rotor (20) in the radial direction (R).

[0010] According to the first aspect, the case discharge port (63, 64) is formed on the case outer wall portion (58) on the outer side (Ra) in the radial direction (R). The case discharge port (63, 64) is located between the first position (Ka) and the second position (Kb) in the axial direction (X). The case discharge port (63, 64) and the discharge port (65, 66) are not greatly separated from each other in the axial direction (X). The case discharge port (63, 64) is likely to be located near the discharge port (65, 66) in the axial direction (X).

[0011] The fluid (W) is less likely to change direction from the radial direction (R) to the axial direction (X) in the flow path from the discharge port (65, 66) to the case-side discharge port (63, 64). The fluid (W) compressed in the compression chamber (S1, S2) flows to the outside (Ra) in the radial direction (R) from the compression chamber (S1, S2) toward the discharge port (65, 66), and then flows almost to the outside (Ra) in the radial direction (R) with almost no change in direction in the axial direction (X), and is discharged to the outside of the casing (50) through the case-side discharge port (63, 64).

[0012] The fluid (W) compressed in the compression chambers (S1, S2) is less likely to experience pressure loss until it is discharged to the outside of the casing (50) through the discharge ports (65, 66) and the case-side discharge ports (63, 64). As described above, the pressure loss of the fluid (W) can be suppressed in the screw compressor (1).

[0013] In a second aspect of the present disclosure, in the first aspect, the gate rotor (30, 35) is housed in a gate rotor chamber (59, 61) provided in the casing (50), a gate opening (60, 62) communicating with the gate rotor chamber (59, 61) is provided in the case outer wall portion, the case side discharge port (63, 64) and the gate opening (60, 62) are covered with a cap (91, 93), and the cap (91, 93) is provided with a cap side discharge path (94, 97) communicating with the case side discharge port (63, 64).

[0014] The gate rotor chamber (59, 61) in which the gate rotor (30, 35) is housed is usually located near the discharge port (65, 66) in the axial direction (X). The cap (91, 93) covering the gate opening (60, 62) is also usually located near the discharge port (65, 66) in the axial direction (X). The fact that the case-side discharge port (63, 64) is covered by the cap (91, 93) together with the gate opening (60, 62) means that the case-side discharge port (63, 64) is located near the discharge port (65, 66) in the axial direction (X). In addition, by providing the cap (91, 93) with a cap-side discharge passage (94, 97) communicating with the case-side discharge port (63, 64), the fluid (W) can flow from the casing (50) side to the cap (91, 93) side.

[0015] In a third aspect of the present disclosure, in the second aspect, the case side discharge port (63, 64) is flush with a case side mounting surface (58a, 58b) of the case outer wall portion (58) for the cap (91, 93), and the case side mounting surface (58a, 58b) and the cap (91, 93) are sealed with a first seal member (92).

[0016] According to the third aspect, since the case side discharge port (63, 64) is flush with the case side mounting surface (58a, 58b), by sealing the case side mounting surface (58a, 58b) and the cap (91, 93) with the first seal member (92), it is possible to prevent the fluid (W) discharged from the case side discharge port (63, 64) from leaking from the gap between the case side mounting surface (58a, 58b) and the cap (91, 93).

[0017] In a fourth aspect of the present disclosure, in the second aspect, the cap side discharge passage (94, 97) includes a cap side insertion tube (94c, 97c) inserted into the case side discharge outlet (63, 64), and the case side discharge outlet (63, 64) and the cap side insertion tube (94c, 97c) are sealed with a second seal member (101).

[0018] According to the fourth aspect, it is possible to prevent the fluid (W) discharged from the case-side discharge port (63, 64) from leaking to the outside before it reaches the cap-side discharge path (94, 97).

[0019] According to a fifth aspect of the present disclosure, in the first to fourth aspects, the case-side discharge port (63, 64) is located so as to overlap with the discharge port (65, 66) in the axial direction (X).

[0020] According to the fifth aspect, the case-side discharge port (63, 64) can be positioned even closer to the discharge port (65, 66) in the axial direction (X). This is advantageous in preventing the fluid (W), which flows from the compression chambers (S1, S2) to the outside (Ra) in the radial direction (R) toward the discharge port (65, 66), from changing direction in the axial direction (X) before reaching the case-side discharge port (63, 64).

[0021] In a sixth aspect of the present disclosure, in the first to fifth aspects, the casing (50) is provided with a connection path (67, 68) that connects the case-side discharge port (63, 64) and the discharge port (65, 66), and the connection path (67, 68) extends straight.

[0022] According to the sixth aspect, the connecting paths (67, 68) extend straight, which is advantageous in reducing the pressure loss of the fluid (W) flowing through the connecting paths (67, 68).

[0023] According to a seventh aspect of the present disclosure, in the first to sixth aspects, a discharge pipe (95, 98) is connected to the case-side discharge port (63, 64), and a sound-deadening material (96) is provided in the discharge pipe (95, 98).

[0024] According to the seventh aspect, the provision of the sound deadening material (96) in the discharge pipes (95, 98) is advantageous in suppressing noise caused by the fluid (W) flowing through the discharge pipes (95, 98).

[0025] In an eighth aspect of the present disclosure, in the first to seventh aspects, the screw compressor (1) includes a bearing holder (73) that holds a bearing (74) that supports the screw rotor (20), and a retaining member (77) that presses the bearing holder (73) in the axial direction (X), and the retaining member (77) is plate-shaped with its thickness direction (t) aligned in the axial direction (X).

[0026] According to the eighth aspect, the holding member (77) is plate-shaped with the thickness direction (t) aligned in the axial direction (X), which is advantageous in reducing the dimension of the screw compressor (1) in the axial direction (X).

[0027] In a ninth aspect of the present disclosure, in any of the first to eighth aspects, the screw compressor (1) includes slide valves (87, 89) that adjust the opening (C) of the discharge ports (S1, S2) by moving in the axial direction (X).

[0028] According to the ninth aspect, the apparent volumes of the compression chambers (S1, S2) can be easily adjusted by adjusting the opening (C) of the discharge ports (65, 66) with the slide valves (87, 89).

[0029] In a tenth aspect of the present disclosure, in the first to ninth aspects, the screw compressor (1) includes a first gate rotor (30) and a second gate rotor (35) as the gate rotor (30, 35), the screw rotor (20), the first gate rotor (30), and the casing (50) form a first compression chamber (S1) as the compression chamber (S1, S2), the screw rotor (20), the second gate rotor (35), and the casing (50) form a second compression chamber (S2) as the compression chamber (S1, S2), and a first case-side discharge port (63) and a second case-side discharge port (64) as the case-side discharge port (63, 64) are formed in the case outer wall portion (58). a first discharge port (65) as the discharge port (65, 66) is formed in a portion (55c) of the casing (50) facing the first compression chamber (S1), and a second discharge port (66) as the discharge port (65, 66) is formed in a portion (55d) of the casing (50) facing the second compression chamber (S2), the first discharge port (65) is in communication with the first case-side discharge port (63), and the second discharge port (66) is in communication with the second case-side discharge port (64), and the first case-side discharge port (63) and the second case-side discharge port (64) are at different positions from each other in the circumferential direction (θ) of the screw rotor (20).

[0030] According to the tenth aspect, the first case side discharge port (63) and the second case side discharge port (64) are located at different positions from each other in the circumferential direction (θ), so that both the first case side discharge port (63) and the second case side discharge port (64) can be positioned between the first position (Ka) and the second position (Kb) in the axial direction (X) without interfering with each other.

[0031] In an eleventh aspect of the present disclosure, in the tenth aspect, a first discharge pipe (95) is connected to the first case side discharge port (63), and a second discharge pipe (98) is connected to the second case side discharge port (64), and the first discharge pipe (95) and the second discharge pipe (98) are joined at a junction (99), so that the pulsation (U) of the fluid (W) from the first discharge port (65) to the junction (99) via the first case side discharge port (63) and the first discharge pipe (95) and the pulsation (U) of the fluid (W) from the second discharge port (66) to the junction (99) via the second case side discharge port (64) and the second discharge pipe (98) cancel each other out.

[0032] According to the eleventh aspect, it is advantageous in suppressing noise and vibration caused by the pulsation (U) of the fluid (W).

[0033] In a twelfth aspect of the present disclosure, in the tenth aspect, the first compression chamber (S1) compresses the fluid (W) at a first pressure (P1) to an intermediate pressure (Pm) that is higher than the first pressure (P1), and the second compression chamber (S2) compresses the fluid (W) at the intermediate pressure (Pm) to a second pressure (S2) that is higher than the intermediate pressure (Pm), and the fluid (W) flows in the order of the first compression chamber (S1), the first discharge port (65), the first case side discharge port (63), the second compression chamber (S2), the second discharge port (66), and the second case side discharge port (64).

[0034] According to the twelfth aspect, the fluid (W) can be compressed in at least two stages by the first compression chamber (S1) and the second compression chamber (S2). [Brief description of the drawings]

[0035] [Figure 1] FIG. 1 is a right side view of a screw compressor according to a first embodiment. [Diagram 2] FIG. 2 shows the screw compressor (1) in a left side view. [Diagram 3]FIG. 3 shows the screw compressor (1) in a front view. [Figure 4] FIG. 4 shows the screw compressor 1 in a right side cross-sectional view taken along line IV in FIG. [Diagram 5] FIG. 5 shows a front cross-sectional view of the screw compressor (1) taken along line V in FIG. [Figure 6] FIG. 6 shows a front cross-sectional view of the screw compressor (1) taken along line VI in FIG. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII in FIG. 6 and showing the vicinity of the first discharge port (65). [Figure 8] FIG. 8 is a cross-sectional view showing the positional relationship between the first case discharge port (63) and the first discharge port (65) without the first slide valve (87). [Figure 9] FIG. 9 shows the positional relationship between the first case discharge port (63) and the first gate opening (60) in a view taken along line IX in FIG. [Figure 10] FIG. 10 shows the screw compressor (1) in a front cross-sectional view taken along the X-ray line of FIG. [Figure 11] FIG. 11 shows a front cross-sectional view of the screw compressor 1 taken along line XI in FIG. [Figure 12] FIG. 12 shows a right side cross-sectional view of the positional relationship between the rotor (A) and the communication passage (F). [Figure 13] FIG. 13 is a view corresponding to FIG. 3 according to the second embodiment, showing the screw compressor (1) in a front view. [Figure 14] FIG. 14 shows the cap-side discharge passages (94, 97) according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] First Embodiment (Screw Compressor) A screw compressor (1) according to a first embodiment will be described. The screw compressor (1) is applied to a refrigeration device such as an air conditioner. The refrigeration device includes a refrigerant circuit through which a refrigerant circulates. The screw compressor (1) compresses the refrigerant in the refrigerant circuit. In the refrigerant circuit, a vapor compression refrigeration cycle is performed by circulating the refrigerant. Figures 1 to 5 show a screw compressor (1) according to a first embodiment. In the following description, the left side of Figure 1 may be referred to as the front side, the right side of Figure 1 as the rear side, the upper side of Figure 1 as the upper side, the lower side of Figure 1 as the lower side, the rear side of Figure 1 as the left side, and the front side of Figure 1 as the right side. Figure 1 is a right side view, Figure 2 is a left side view, Figure 3 is a front view, Figure 4 is a right side cross-sectional view taken along line IV in Figure 3, and Figure 5 is a front cross-sectional view taken along line V in Figure 4. The front-rear and left-right directions constitute the horizontal direction. The up-down direction constitutes the vertical direction (V).

[0037] The screw compressor (1) includes a shaft (10), a screw rotor (20), a first gate rotor (30), a second gate rotor (35), a motor (40), and a casing (50).

[0038] The screw compressor (1) includes a front cover (70), a front bearing (71), a front bearing holder (72), a rear bearing holder (73), a rear bearing (74), a spacer (75), a snap ring (76), a retaining member (77), an intermediate bearing (78), a base end first gate bearing (79), a tip end first gate bearing (80), a base end first gate bearing holder (81), a tip end first gate bearing holder (82), a base end second gate bearing (83), a tip end second gate bearing (84), a base end second gate bearing holder (85), and a tip end second gate bearing holder (86).

[0039] The screw compressor (1) includes a first slide valve (87), a first valve moving mechanism (88), a second slide valve (89), a second valve moving mechanism (90), a first cap (91), a gasket (92) as a first sealing member, a second cap (93), a first cap side discharge passage (94), a first discharge pipe (95), a sound-absorbing material (96), a second cap side discharge passage (97), and a second discharge pipe (98).

[0040] (shaft) As shown in FIG. 4, the central axis (O) of the shaft (10) extends in the front-rear direction of the horizontal direction. The direction in which the central axis (O) of the shaft (10) extends is referred to as the axial direction (X). The axial direction (X) is the front-rear direction. The screw compressor (1) is placed horizontally. The front side in the axial direction (X) is referred to as the front side (Xa) which is the first direction side in the axial direction (X). The rear side in the axial direction (X) is referred to as the rear side (Xb) which is the second direction side in the axial direction (X). The rear side (Xb) in the axial direction (X) is opposite to the front side (Xa) in the axial direction (X).

[0041] The radial direction (R) of the screw compressor (1) is perpendicular to the axial direction (X). The side in the radial direction (R) that is away from the central axis (O) is called the outer circumferential side (outside) (Ra) of the radial direction (R). The side in the radial direction (R) that is closer to the central axis (O) is called the inner circumferential side (inside) (Rb) of the radial direction (R). The up-down direction, which is part of the radial direction (R), coincides with the vertical direction (V). The upper side of the vertical direction (V) is called the upper side (upper) (Va). The lower side of the vertical direction (V) is called the lower side (lower) (Vb). The circumferential direction (θ) of the screw compressor (1) is the direction around the central axis (O).

[0042] (Screw rotor) The screw rotor (20) is coupled to the shaft (10) and rotates integrally with the shaft (10). The screw rotor (20) extends in the axial direction (X) like the shaft (10). The screw rotor (20) has a plurality of screw grooves (21), a front rotation seal portion (22), and a rear rotation seal portion (23). The screw rotor (20) is made of, for example, a metal.

[0043] The screw grooves (21) are provided in a middle portion in the axial direction (X) on the outer periphery of the screw rotor (20). The screw grooves (21) are aligned in the axial direction (X). The screw grooves (21) are spiral.

[0044] The front rotating seal portion (22) is provided at a front end portion in the axial direction (X) of the outer periphery of the screw rotor (20). The rear rotating seal portion (23) is provided at a rear end portion in the axial direction (X) of the outer periphery of the screw rotor (20). The front rotating seal portion (22) and the rear rotating seal portion (23) are not provided with a screw groove (21).

[0045] (First gate rotor) 5, the first gate rotor (30) is disposed on the outer circumferential side (R) of the screw rotor (20). The first gate rotor (30) is disposed to the left of the screw rotor (20).

[0046] The first gate rotor (30) has a first gate shaft (31) and a first gate (32). The first gate rotor (30) is made of, for example, resin. The first gate shaft (31) extends in the vertical direction (V). The first gate (32) is fixed to a middle portion of the first gate shaft (31). The first gate (32) is substantially disk-shaped and concentric with the first gate shaft (31). A plurality of first gate teeth are provided on the outer periphery of the first gate (32). The first gate teeth of the first gate (32) of the first gate rotor (30) mesh with the screw groove (21) of the screw rotor (20).

[0047] The first gate (32) has a gate radius (r). The gate radius (r) is the radius of the first gate (32). The gate radius (r) is half the diameter of the first gate (32). The gate radius (r) is the distance from the center to the outer periphery of the first gate (32).

[0048] (Second gate rotor) 5, the second gate rotor (35) is disposed on the outer circumferential side (Ra) of the screw rotor (20). The second gate rotor (35) is disposed to the right and below (Vb) the screw rotor (20).

[0049] The second gate rotor (35) has a second gate shaft (36) and a second gate (37). The second gate rotor (35) is made of, for example, resin. The second gate shaft (36) extends obliquely with respect to the vertical direction (V). The second gate shaft (36) extends to the right as it approaches the upper side (Va). The second gate (37) is fixed to a middle portion of the second gate shaft (36). The second gate (37) is substantially disk-shaped and concentric with the second gate shaft (36). A plurality of second gate teeth are provided on the outer periphery of the second gate (37). The second gate teeth of the second gate (37) of the second gate rotor (35) mesh with the screw groove (21) of the screw rotor (20).

[0050] The second gate (37) has a gate radius (r). The gate radius (r) is the radius of the second gate (37). The gate radius (r) is half the diameter of the second gate (37). The gate radius (r) is the distance from the center to the outer periphery of the second gate (37).

[0051] (Motor) As shown in Fig. 4, the motor (40) includes a motor rotor (41) and a motor stator (42). The motor rotor (41) is coupled to the shaft (10) and rotates integrally with the shaft (10). The motor rotor (41) is disposed forward (Xa) of the screw rotor (20) in the axial direction (X). The motor stator (42) is fixed to an inner wall of a casing (50) described later via a fastener (not shown). The motor rotor (41) and the motor stator (42) face each other with a predetermined gap therebetween in the radial direction (R).

[0052] (Casing) As shown in Figures 1 to 4, the casing (50) is substantially cylindrical. As shown in Figure 4, a front opening (50a) is provided at the front end of the casing (50). A rear opening (50b) is provided at the rear end of the casing (50). The casing (50) is divided in the axial direction (X) by a partition wall (53) into a motor accommodating section (51) on the front side (Xa) in the axial direction (X) and a compression chamber forming section (52) on the rear side (Xb) in the axial direction (X).

[0053] As shown in Fig. 4, a motor chamber (54) is provided in the motor housing portion (51) of the casing (50). The motor chamber (54) is a cavity formed in the casing (50). The motor chamber (54) houses the shaft (10) and the motor (40). The motor rotor (41) and the motor stator (42) of the motor (40) are housed in the motor chamber (54). A front end of the shaft (10) and a front end of the motor (40) protrude forward (Xa) from the motor chamber (54) through the front opening (50a).

[0054] The front cover (70) covers the front opening (50a) of the casing (50). An inner protrusion (70a) protruding toward the inner periphery (Rb) is provided on the inner wall of the front cover (70). The front bearing (71) is held by the inner protrusion (70a) of the front cover (70). The front bearing (71) supports the front end of the shaft (10) so as to be rotatable relative to the front cover (70). The front bearing holder (72) holds the front bearing (71) relative to the front cover (70).

[0055] As shown in Fig. 4, a cylindrical wall portion (55) is provided in the compression chamber forming portion (52) of the casing (50). The screw rotor (20) is disposed in a front portion of the cylindrical wall portion (55) in the axial direction (X). A rear bearing holder (73), which will be described later, is disposed in a rear portion of the cylindrical wall portion (55) in the axial direction (X).

[0056] As shown in Fig. 5, the inner peripheral surface of the cylindrical wall portion (55) of the casing (50) covers the screw grooves (21) of the screw rotor (20) from the outer peripheral side (Ra) in the radial direction (R). The inner diameter of the cylindrical wall portion (55) is slightly larger than the outer diameter of the screw rotor (20). The cylindrical wall portion (55) is provided with a first slit (56) through which the first gate (32) passes. The cylindrical wall portion (55) is provided with a second slit (57) through which the second gate (37) passes.

[0057] 4, a front stationary seal portion (55a) is provided on the inner circumferential surface of the cylindrical wall portion (55) of the casing (50), facing the front rotating seal portion (22) of the screw rotor (20) (hereinafter referred to as the "front stationary seal portion (55a)"). A rear stationary seal portion (55b) is provided on the inner circumferential surface of the cylindrical wall portion (55) of the casing (50), facing the rear rotating seal portion (23) of the screw rotor (20) (hereinafter referred to as the "rear stationary seal portion (55b)").

[0058] As described above, as shown in Fig. 4, the rear bearing holder (73) is disposed in the rear portion of the cylindrical wall portion (55) in the axial direction (X). The rear bearing holder (73) is held by the inner peripheral surface of the cylindrical wall portion (55). The rear bearing holder (73) is substantially cylindrical. The rear bearing holder (73) includes a first portion (73a) extending in the axial direction (X) and a second portion (73b) extending from a front end portion of the first portion (73a) toward the inner peripheral side (Rb) in the radial direction (R).

[0059] There are two rear bearings (74). The two rear bearings (74) are aligned in the axial direction (X). The rear bearings (74) are disposed between the first portion (73a) of the rear bearing holder (73) and the rear end portion of the shaft (10) in the radial direction (R). The rear bearing holder (73) holds the rear bearing (74). Specifically, the inner peripheral surface of the first portion (73a) of the rear bearing holder (73) holds the outer peripheral surface of the rear bearing (74).

[0060] The rear bearing (74) rotatably supports the rear end of the shaft (10) relative to the cylindrical wall portion (55) of the casing (50). The rear bearing (74) rotatably supports the screw rotor (20) via the shaft (10).

[0061] The spacer (75) is interposed between the second portion (73b) of the rear bearing holder (73) and the front row of rear bearings (74). The snap ring (76) is disposed at the rear end of the rear row of rear bearings (74). The snap ring (76) positions the rear bearings (74) in the axial direction (X).

[0062] The holding member (77) covers the rear opening (50b) of the casing (50). The holding member (77) is plate-shaped. The thickness direction (t) of the holding member (77) is the axial direction (X). The holding member (77) is substantially disk-shaped. The shorter side of the holding member (77) in the axial direction (X) is shorter than the radial direction (R).

[0063] The front surface of the retaining member (77) is in contact with the rear end of the first portion (73a) of the rear bearing holder (73). The retaining member (77) presses the rear bearing holder (73) toward the front side (Xa) in the axial direction (X). The retaining member (77) retains the rear bearing holder (73) against the cylindrical wall portion (55) of the casing (50).

[0064] As described above, as shown in Fig. 4, the partition wall (53) divides the casing (50) in the axial direction (X) into a motor accommodating portion (51) and a compression chamber forming portion (52). The partition wall (53) extends in the radial direction (R). The partition wall (53) is disposed forward (Xa) in the axial direction (X) of the cylindrical wall (55). The front surface of the partition wall (53) faces the motor chamber (54). The rear surface of the partition wall (53) faces the front end of the screw rotor (20).

[0065] A shaft through hole (53a) is provided in the partition wall portion (53). The shaft through hole (53a) passes through the partition wall portion (53) in the axial direction (X). The shaft (10) passes through the shaft through hole (53a) in the axial direction (X).

[0066] The intermediate bearing (78) is disposed in the shaft through hole (53a) in the partition wall portion (53). The intermediate bearing (78) supports the shaft (10) rotatably relative to the partition wall portion (53) of the casing (50).

[0067] The front bearing (71), the rear bearing (74), and the intermediate bearing (78) rotatably support the shaft (10) relative to the casing (50). The casing (50) rotatably holds the shaft (10). The casing (50) rotatably holds the screw rotor (20). The casing (50) rotatably holds the motor rotor (41).

[0068] (External wall of case) 3 to 5, the casing (50) has a case outer wall portion (58) on the outer periphery side (Ra) in the radial direction (R). The case outer wall portion (58) is a wall portion disposed on the outer periphery side (Ra) in the radial direction (R) of the casing (50).

[0069] (Gate rotor room) As shown in Fig. 5, the casing (50) is provided with a first gate rotor chamber (59). The first gate rotor chamber (59) is formed on the outer periphery side (Ra) of the cylindrical wall portion (55) of the casing (50) in the radial direction (R). The first gate rotor chamber (59) is formed on the left side of the cylindrical wall portion (55) of the casing (50). The first gate rotor chamber (59) and the first compression chamber (S1) communicate with each other via the first slit (56).

[0070] The first gate rotor (30) is housed in a first gate rotor chamber (59). The first gate rotor chamber (59) further houses a base end first gate bearing (79), a tip end first gate bearing (80), a base end first gate bearing holder (81), and a tip end first gate bearing holder (82).

[0071] There is one base-side first gate bearing (79). The base-side first gate bearing (79) rotatably supports the base end (upper end) of the first gate shaft (31) of the first gate rotor (30). There are two tip-side first gate bearings (80). The tip-side first gate bearing (80) rotatably supports the tip end (lower end) of the first gate shaft (31) of the first gate rotor (30).

[0072] The base-end first gate bearing holder (81) is disposed above (Va) the first gate rotor (30). The base-end first gate bearing holder (81) holds the base-end first gate bearing (79) relative to the casing (50). The base-end first gate bearing holder (81) is detachable from the above (Va) relative to the first gate rotor chamber (59) of the casing (50).

[0073] The tip side first gate bearing holder (82) is disposed below (Vb) the first gate rotor (30). The tip side first gate bearing holder (82) holds the tip side first gate bearing (80). The tip side first gate bearing holder (82) is detachable from the below (Vb) with respect to the first gate rotor chamber (59) of the casing (50).

[0074] A first gate opening (60) is provided in the left case outer wall portion (58) of the casing (50). The first gate opening (60) communicates with the first gate rotor chamber (59).

[0075] As shown in Fig. 5, the casing (50) is provided with a second gate rotor chamber (61). The second gate rotor chamber (61) is formed on the outer circumferential side (Ra) of the cylindrical wall portion (55) of the casing (50) in the radial direction (R). The second gate rotor chamber (61) is formed on the right side and lower side (Vb) of the cylindrical wall portion (55) of the casing (50). The second gate rotor chamber (61) and the second compression chamber (S2) are in communication with each other via the second slit (57).

[0076] The second gate rotor (35) is housed in a second gate rotor chamber (61). The second gate rotor chamber (61) further houses a base end second gate bearing (83), a tip end second gate bearing (84), a base end second gate bearing holder (85), and a tip end second gate bearing holder (86).

[0077] There is one base-side second gate bearing (83). The base-side second gate bearing (83) rotatably supports the base end (the lower and left end) of the second gate shaft (36) of the second gate rotor (35). There are three tip-side second gate bearings (84). The tip-side second gate bearing (84) rotatably supports the tip end (the upper and right end) of the second gate shaft (36) of the second gate rotor (35).

[0078] The base-end second gate bearing holder (85) is disposed below (Vb) and to the left of the second gate rotor (35). The base-end second gate bearing holder (85) holds the base-end second gate bearing (83). The base-end second gate bearing holder (85) is detachable from the below (Vb) and to the left of the second gate rotor chamber (61) of the casing (50).

[0079] The tip side second gate bearing holder (86) is disposed above (Va) and to the right of the second gate rotor (35). The tip side second gate bearing holder (86) holds the tip side second gate bearing (84). The tip side second gate bearing holder (86) is detachable from the above (Va) and right side of the second gate rotor chamber (61) of the casing (50).

[0080] A second gate opening (62) is provided in the lower (Vb) and right-hand case outer wall portion (58) of the casing (50). The second gate opening (62) communicates with the second gate rotor chamber (61).

[0081] (Compression chamber) As shown in Fig. 5, the screw groove (21) of the screw rotor (20), the first gate (32) of the first gate rotor (30), and the cylindrical wall portion (55) of the casing (50) form a first compression chamber (S1). The first compression chamber (S1) compresses a working fluid (W). The screw groove (21) of the screw rotor (20), the second gate (37) of the second gate rotor (35), and the cylindrical wall portion (55) of the casing (50) form a second compression chamber (S2). The second compression chamber (S2) compresses the working fluid (W). The working fluid (W) is, for example, a refrigerant gas.

[0082] The first compression chamber (S1) is located above (Va) the central axis (O) of the screw rotor (20) (shaft (10)) in the vertical direction (V). Specifically, when the first compression chamber (S1) is represented by a first range (S1a) in the circumferential direction (θ) around the central axis (O), the majority of the entire first compression chamber (S1) (first range (S1a)) is located above (Va) the central axis (O) in the vertical direction (V) (see FIG. 6).

[0083] The second compression chamber (S2) is located below (Vb) in the vertical direction (V) of the central axis (O) of the screw rotor (20) (shaft (10)). Specifically, when the second compression chamber (S2) is represented by a second range (S2a) in the circumferential direction (θ) around the central axis (O), the majority of the entire second compression chamber (S2) (second range (S2a)) is located below (Vb) in the vertical direction (V) of the central axis (O) (see FIG. 6).

[0084] (Case side outlet) Fig. 6 shows a front cross-sectional view of the screw compressor (1) taken along line VI in Fig. 4. A first case discharge port (63) is provided in the left case outer wall portion (58) of the casing (50). The working fluid (W) is discharged from the first case discharge port (63) to the outside of the casing (50). A second case discharge port (64) is provided in the lower (Vb) and right case outer wall portion (58) of the casing (50). The working fluid (W) is discharged from the second case discharge port (64) to the outside of the casing (50).

[0085] (Discharge port) As shown in Fig. 6, a first discharge port (65) is formed in a portion (55c) of the cylindrical wall portion (55) of the casing (50) facing the first compression chamber (S1). The first discharge port (65) is disposed on the upper side (Va) and the left side with respect to the screw rotor (20). The first discharge port (65) is formed on the inner circumferential surface of the cylindrical wall portion (55). The first discharge port (65) is formed in a substantially semicircular shape when viewed in the axial direction (X). The first discharge port (65) communicates with the first compression chamber (S1).

[0086] A second discharge port (66) is formed in a portion (55d) of the cylindrical wall portion (55) of the casing (50) facing the second compression chamber (S2). The second discharge port (66) is disposed on the lower side (Vb) and the right side of the screw rotor (20). The second discharge port (66) is formed on the inner circumferential surface of the cylindrical wall portion (55). The second discharge port (66) is formed in a substantially semicircular shape when viewed in the axial direction (X). The second discharge port (66) communicates with the second compression chamber (S2).

[0087] As shown in FIG. 6, the first case discharge port (63) and the second case discharge port (64) are located at different positions in the circumferential direction (θ) (direction around the central axis (O)) of the screw rotor (20).

[0088] (Connecting road) As shown in Fig. 6, the casing (50) is provided with a first connection passage (67). The first connection passage (67) is formed by drilling a hole in a wall of the casing (50). The first connection passage (67) crosses the first gate rotor chamber (59) in the casing (50) in the left-right direction. The first connection passage (67) connects the first case discharge port (63) and the first discharge port (65). The first discharge port (65) communicates with the first case discharge port (63) through the first connection passage (67). The first connection passage (67) extends straight.

[0089] The casing (50) is provided with a second connection passage (68). The second connection passage (67) is formed by drilling a hole in a wall of the casing (50). The second connection passage (68) crosses the second gate rotor chamber (61) in the casing (50) at an angle with respect to the up-down and left-right directions. The second connection passage (68) connects the second case discharge port (64) and the second discharge port (66). The second discharge port (66) is in communication with the second case discharge port (64) via the second connection passage (68). The second connection passage (68) extends straight.

[0090] (Slide valve) Fig. 7 is a cross-sectional view taken along line VII in Fig. 6 near the first discharge port (65). As described above, the first discharge port (65) is formed in the portion (55c) of the cylindrical wall portion (55) of the casing (50) facing the first compression chamber (S1). In the first discharge port (65), the first slide valve (87) moves in the axial direction (X).

[0091] When the first slide valve (87) moves in the axial direction (X), the position of the first slide valve (87) with respect to the first compression chamber (S1) changes. The first slide valve (87) adjusts the opening degree (C) of the first discharge port (65) by moving in the axial direction (X). When the first slide valve (87) is positioned at the front end position (Ja), the first slide valve (87) blocks the space between the first compression chamber (S1) and the first discharge port (65), so that the opening degree (C) of the first discharge port (65) is reduced. When the first slide valve (87) is positioned at the rear end position (Jb) (see the two-dot chain line), the space between the first compression chamber (S1) and the first discharge port (65) is opened, so that the opening degree (C) of the first discharge port (65) is increased.

[0092] The first valve moving mechanism (88) moves the first slide valve (87) in the axial direction (X). The first valve moving mechanism (88) is composed of a cylinder-piston mechanism. The first valve moving mechanism (88) has a cylinder (88a), a piston (88b), and a rod (88c). The piston (88b) is disposed in the cylinder (88a). The rod (88c) extends from the front surface of the piston (88b) to the front side (X) in the axial direction (X) and is connected to the rear end of the first slide valve (87).

[0093] A pressure control chamber (88d) is formed in the cylinder (88a) on the rear side (Xb) of the piston (88b) in the axial direction (X). When high pressure is introduced into the pressure control chamber (88d), the first slide valve (87) moves to the front side (Xa) in the axial direction (X) together with the piston (88b) and the rod (88c). Although not shown, the first valve moving mechanism (88) biases the first slide valve (87) to the rear side (Xb) in the axial direction (X) by a spring.

[0094] Although detailed description will be omitted, in the second discharge port (66), a second slide valve (89) (see FIG. 6) moves in the axial direction (X). The second slide valve (89) adjusts the opening (C) of the second discharge port (66) by moving in the axial direction (X). The second valve moving mechanism (90) (see FIGS. 1 and 2) moves the second slide valve (89) in the axial direction (X). The detailed structures of the second slide valve (89) and the second valve moving mechanism (90) are similar to those of the first slide valve (87) and the first valve moving mechanism (88).

[0095] (Positional relationship between the discharge port on the case side and the discharge port) FIG. 8 is a cross-sectional view showing the positional relationship between the first case discharge port (63) and the first discharge port (65) without the first slide valve (87).

[0096] 8, the first discharge port (65) includes a front end (65a) as a first end and a rear end (65b) as a second end. The front end (65a) is an end of the first discharge port (65) on the front side (Xa) in the axial direction (X). The rear end (65b) is an end of the first discharge port (65) on the rear side (Xb) in the axial direction (X).

[0097] A position that is separated from the front end (65a) of the first discharge port (65) by the gate radius (r) of the first gate (32) toward the front side (Xa) in the axial direction (X) is defined as a front position (Ka) as a first position. A position that is separated from the rear end (65b) of the first discharge port (65) by the gate radius (r) of the first gate (32) toward the rear side (Xb) in the axial direction (X) is defined as a rear position (Kb) as a second position.

[0098] The first case discharge port (63) is located between the front position (Ka) and the rear position (Kb) in the axial direction (X). The first case discharge port (63) is located so as to overlap with the first discharge port (65) in the axial direction (X).

[0099] At least a part of the opening width (B) in the axial direction (X) of the first case discharge port (63) is located between a front position (Ka) and a rear position (Kb) in the axial direction (X).

[0100] 6, the first case discharge port (63) is located closer to the first discharge port (65) in the radial direction (R) than the screw rotor (20). The distance between the first case discharge port (63) and the first discharge port (65) in the radial direction (R) is shorter than the distance between the first case discharge port (63) and the screw rotor (20) in the radial direction (R).

[0101] The positional relationship between the second case discharge port (64) and the second discharge port (66) is also almost the same as the positional relationship between the first case discharge port (63) and the first discharge port (65). Strictly speaking, the positional relationship between the second case discharge port (64) and the second discharge port (66) is slightly different, but for simplicity's sake, it is shown in Fig. 8 by reference characters in parentheses. In the description of the positional relationship between the second case discharge port (64) and the second discharge port (66), detailed description of matters similar to the positional relationship between the first case discharge port (63) and the first discharge port (65) may be omitted.

[0102] 8, the second discharge port (66) includes a front end (66a) as a first end and a rear end (66b) as a second end. The front end (66a) is an end of the second discharge port (66) on the front side (Xa) in the axial direction (X). The rear end (66b) is an end of the second discharge port (66) on the rear side (Xb) in the axial direction (X).

[0103] A position that is separated from the front end (66a) of the second discharge port (66) by the gate radius (r) of the second gate (37) toward the front side (Xa) in the axial direction (X) is defined as a front position (Ka) as a first position. A position that is separated from the rear end (66b) of the second discharge port (66) by the gate radius (r) of the second gate (37) toward the rear side (Xb) in the axial direction (X) is defined as a rear position (Kb) as a second position.

[0104] The second case discharge port (64) is located between the front position (Ka) and the rear position (Kb) in the axial direction (X). The second case discharge port (64) is located so as to overlap with the second discharge port (66) in the axial direction (X).

[0105] As shown in FIG. 6, the second case discharge port (64) is located closer to the second discharge port (66) than the screw rotor (20) is in the radial direction (R).

[0106] (Positional relationship between the discharge port on the case side and the gate opening) FIG. 9 shows the positional relationship between the first case discharge port (63) and the first gate opening (60) in a cross-sectional view taken along line IX in FIG.

[0107] 6 and 9, the first gate shaft (31) and the first gate (32) of the first gate rotor (30) can be seen through the first gate opening (60). The first case-side discharge port (63) is disposed inside the first gate opening (60).

[0108] The first case discharge port (63) and the first gate opening (60) are covered by a common first cap (91). The first cap (91) is also called a side cap. The first cap (91) is substantially disk-shaped. A first case mounting surface (58a) is provided on the periphery of the first gate opening (60) of the case outer wall portion (58). The first cap (91) is attached to the first case mounting surface (58a). The first case discharge port (63) is flush with the first case mounting surface (58a) of the case outer wall portion (58) that is attached to the first cap (91).

[0109] The first case discharge port (63) and the first case mounting surface (58a) being flush with each other means that there is almost no difference in level between the outer circumferential edge of the first case discharge port (63) and the first case mounting surface (58a). The difference in level between the two is preferably 1 mm or less, more preferably 0.5 mm or less, and even more preferably 0.1 mm or less.

[0110] As shown in Fig. 6, a gasket (92) is disposed between the first case mounting surface (58a) and the first cap (91). The gasket (92) is a sheet gasket or a spiral gasket. An O-ring may be used as the gasket (92). The first case mounting surface (58a) and the first cap (91) are sealed with each other by the gasket (92).

[0111] The positional relationship between the second case discharge port (64) and the second gate opening (62) is also almost the same as the positional relationship between the first case discharge port (63) and the first gate opening (60). Strictly speaking, the positional relationship between the second case discharge port (64) and the second gate opening (62) is slightly different, but for simplicity's sake, it is shown in Fig. 9 using symbols in parentheses. Note that, in describing the positional relationship between the second case discharge port (64) and the second gate opening (62), detailed description of matters similar to the positional relationship between the first case discharge port (63) and the first gate opening (60) may be omitted.

[0112] The second case discharge port (64) and the second gate opening (62) are covered by a common second cap (93). The second case discharge port (64) is flush with a second case mounting surface (58b) of the case outer wall portion (58) that is attached to the second cap (93). The second case mounting surface (58b) and the second cap (93) are sealed with a gasket (92).

[0113] (cap) As shown in FIG. 6, the first cap (91) is provided with a first cap discharge passage (94). The first cap discharge passage (94) includes a hole (94a) and a pipe (94b). The hole (94a) of the first cap discharge passage (94) penetrates the first cap (91) in the radial direction (R). The hole (94a) of the first cap discharge passage (94) is connected to the first case discharge port (63). The first cap discharge passage (94) communicates with the first case discharge port (63). The pipe (94b) of the first cap discharge passage (94) is located on the outer periphery side (Ra) of the first cap (91) in the radial direction (R) and extends in the radial direction (R). The first cap (91) and the first cap discharge passage (94) are integrally formed.

[0114] One end of the first discharge pipe (95) is connected to an end of the first cap discharge passage (94). In other words, the first discharge pipe (95) is connected to the first case discharge port (63) through the first cap discharge passage (94). The first discharge pipe (95) communicates with the first cap discharge passage (94). In other words, the first discharge pipe (95) communicates with the first case discharge port (63) through the first cap discharge passage (94). The other end of the first discharge pipe (95) is connected to a second suction port (69c) described later.

[0115] The first discharge pipe (95) is provided with a sound deadening material (96). More specifically, the sound deadening material (96) is wrapped around the outer periphery of the first discharge pipe (95). The sound deadening material (96) is made of, for example, sponge or polyurethane.

[0116] As shown in FIG. 6, the second cap (93) is provided with a second cap discharge passage (97). The second cap discharge passage (97) includes a hole (97a) and a pipe (97b). The hole (97a) of the second cap discharge passage (97) penetrates the second cap (93) in the radial direction (R). The hole (97a) of the second cap discharge passage (97) is connected to the second case discharge port (64). The second cap discharge passage (97) communicates with the second case discharge port (64). The pipe (97b) of the second cap discharge passage (97) is located on the outer periphery side (Ra) of the second cap (93) in the radial direction (R) and extends in the radial direction (R). The second cap (93) and the second cap discharge passage (97) are integrally formed.

[0117] One end of the second discharge pipe (98) is connected to an end of the second cap discharge passage (97). In other words, the second discharge pipe (98) is connected to the second case discharge port (64) through the second cap discharge passage (97). The second discharge pipe (98) is in communication with the second cap discharge passage (97). In other words, the second discharge pipe (98) is in communication with the second case discharge port (64) through the second cap discharge passage (97). The other end of the second discharge pipe (98) is connected to, for example, a condenser in the refrigerant circuit. The second discharge pipe (98) is provided with a sound-deadening material (96). In particular, the sound-deadening material (96) is wrapped around the outer periphery of the second discharge pipe (98).

[0118] (Intake port) 4, a first suction port (69a) is provided in an upper portion of the case outer wall portion (58) in the compression chamber forming portion (52) of the casing (50). The first suction port (69a) communicates with the first compression chamber (S1) through a first suction passage (69b) provided in the cylindrical wall portion (55).

[0119] As shown in Fig. 4, a second suction port (69c) is provided in the case outer wall portion (58) of the motor housing portion (51) of the casing (50). The second suction port (69c) communicates with the motor chamber (54) through a second suction passage (69d).

[0120] (two-stage compression) The screw compressor (1) is a two-stage screw compressor. The first compression chamber (S1) compresses the working fluid (W) at a first pressure (P1) to an intermediate pressure (Pm) that is higher than the first pressure (P1). The second compression chamber (S2) compresses the working fluid (W) at the intermediate pressure (Pm) to a second pressure (P2) that is higher than the intermediate pressure (Pm). The first compression chamber (S1) is also referred to as a low-stage compression chamber. The second compression chamber (S2) is also referred to as a high-stage compression chamber. The first pressure (P1) is also referred to as a low pressure. The second pressure (P2) is also referred to as a high pressure.

[0121] The working fluid (W) flows in the following order: the first suction port (69a), the first suction passage (69b), the first compression chamber (S1), the first discharge port (65), the first connecting passage (67), the first case discharge port (63), the first cap discharge passage (94), the first discharge pipe (95), the second suction port (69c), the second suction passage (69d), the motor chamber (54) as the intermediate chamber (Sm), the second compression chamber (S2), the second discharge port (66), the second connecting passage (68), the second case discharge port (64), the second cap discharge passage (97), and the second discharge pipe (98).

[0122] (Sealing part) Fig. 10 shows the screw compressor (1) in a front cross-sectional view taken along an X-ray line in Fig. 4. As shown in Figs. 4 and 10, the front stationary seal portion (55a) on the inner circumferential surface of the cylindrical wall portion (55) of the casing (50) and the front rotating seal portion (22) of the screw rotor (20) slide against each other with a small gap therebetween in the radial direction (R). As shown in Fig. 10, the front stationary seal portion (55a) is disposed above (Va) the central axis (O) in the vertical direction (V). The front stationary seal portion (55a) and the front rotating seal portion (22) slide against each other above (Va) the central axis (O) in the vertical direction (V).

[0123] 4, the front stationary seal portion (55a) and the front rotating seal portion (22) seal between the motor chamber (54) (middle chamber (Sm)) and the first compression chamber (S1). The motor chamber (54) is sealed by the front stationary seal portion (55a) and the front rotating seal portion (22) and is therefore not in communication with the first compression chamber (S1).

[0124] As described above, the working fluid (W) must flow from the motor chamber (54) to the second compression chamber (S2), not from the motor chamber (54) to the first compression chamber (S1). The front stationary seal portion (55a) and the front rotating seal portion (22) restrict the flow of the working fluid (W) from the motor chamber (54) to the first compression chamber (S1).

[0125] (Communication path) Fig. 11 is a front cross-sectional view of the screw compressor (1) taken along line XI in Fig. 4. As shown in Figs. 4 and 11, a communication hole (53b) is formed in the partition wall (53) of the casing (50). The communication hole (53b) penetrates the partition wall (53) in the axial direction (X).

[0126] The communication hole (53b) constitutes a communication passage (F). In other words, the communication passage (F) includes the communication hole (53b). The communication passage (F) is disposed below (Vb) the central axis (O) in the vertical direction (V).

[0127] The communication passage (F) communicates (connects) the motor chamber (54) and the second compression chamber (S2). The motor chamber (54) communicates with the second compression chamber (S2) through the communication passage (F).

[0128] The communication passage (F) includes an inclined portion (Fa). The inclined portion (Fa) has an upward gradient from a front side (Xa) in the axial direction (X) near the motor chamber (54) toward a rear side (Xb) in the axial direction (X) near the second compression chamber (S2).

[0129] (Positional relationship between the rotor and the communication passage) 12 shows a cross-sectional view of the positional relationship between the rotating body (A) and the communication passage (F). The rotating body (A) includes a shaft (10), a screw rotor (20), and a motor rotor (41). The outermost diameter (DA) of the rotating body (A) is the larger of the outermost diameter (D20) of the screw rotor (20) and the outermost diameter (D41) of the motor rotor (41). In this example, since the outermost diameter (D41) of the motor rotor (41) is larger than the outermost diameter (D20) of the screw rotor (20), the outermost diameter (DA) of the rotating body (A) is the outermost diameter (D41) of the motor rotor (41).

[0130] A lower end (Fb) of the communication passage (F) is located below (Vb) in the vertical direction (V) from the outermost diameter (DA) of the rotor (A).

[0131] (Oil puddle) As shown in Fig. 12, an oil reservoir (G) is formed on the inner bottom surface (50c) of the lower side (Vb) in the vertical direction (V) of the casing (50). Oil (g) is stored in the oil reservoir (G). The oil (g) is contained in the working fluid (W) as mist, is separated in an oil separator (located outside the screw compressor (1), not shown), and is stored in the oil reservoir (G). When a sufficient flow rate of the working fluid (W) is ensured, the height of the oil level (G0) of the oil (g) in the oil reservoir (G) in the vertical direction (V) approximately coincides with the lower end (Fb) of the communication passage (F).

[0132] (Action and effect) According to this embodiment, the case discharge port (63, 64) is formed in the case outer wall portion (58) on the outer periphery side (Ra) in the radial direction (R). The case discharge port (63, 64) is located between the first position (Ka) and the second position (Kb) in the axial direction (X). The case discharge port (63, 64) and the discharge port (65, 66) are not greatly separated from each other in the axial direction (X). The case discharge port (63, 64) is likely to be located near the discharge port (65, 66) in the axial direction (X).

[0133] The fluid (W) is less likely to change direction from the radial direction (R) to the axial direction (X) in the flow path from the discharge port (65, 66) to the case-side discharge port (63, 64). The fluid (W) compressed in the compression chamber (S1, S2) flows toward the outer periphery (Ra) in the radial direction (R) from the compression chamber (S1, S2) toward the discharge port (65, 66), and then flows almost to the outer periphery (Ra) in the radial direction (R) with almost no change in direction in the axial direction (X), and is discharged to the outside of the casing (50) through the case-side discharge port (63, 64).

[0134] The fluid (W) compressed in the compression chambers (S1, S2) is less likely to experience pressure loss until it is discharged to the outside of the casing (50) through the discharge ports (65, 66) and the case-side discharge ports (63, 64). As described above, the pressure loss of the fluid (W) can be suppressed in the screw compressor (1).

[0135] The gate rotor chambers (59, 61) in which the gate rotors (30, 35) are housed are typically located near the discharge ports (65, 66) in the axial direction (X). The caps (91, 93) covering the gate openings (60, 62) are also typically located near the discharge ports (65, 66) in the axial direction (X). The fact that the case-side discharge ports (63, 64) are covered by the caps (91, 93) together with the gate openings (60, 62) means that the case-side discharge ports (63, 64) are located near the discharge ports (65, 66) in the axial direction (X).

[0136] The cap (91, 93) is provided with a cap discharge passage (94, 97) which communicates with the case discharge port (63, 64), thereby allowing the fluid (W) to flow from the casing (50) side to the cap (91, 93) side.

[0137] Since the case side discharge port (63, 64) is flush with the case side mounting surface (58a, 58b), by sealing the case side mounting surface (58a, 58b) and the cap (91, 93) with the first seal member (92), it is possible to prevent the fluid (W) discharged from the case side discharge port (63, 64) from leaking from the gap between the case side mounting surface (58a, 58b) and the cap (91, 93).

[0138] Since the case-side discharge port (63, 64) is located so as to overlap with the discharge port (65, 66) in the axial direction (X), the case-side discharge port (63, 64) can be positioned even closer to the discharge port (65, 66) in the axial direction (X). This is advantageous in preventing the fluid (W) that flows from the compression chambers (S1, S2) toward the discharge port (65, 66) toward the outer periphery (Ra) in the radial direction (R) from changing direction in the axial direction (X) before reaching the case-side discharge port (63, 64).

[0139] The connecting passages (67, 68) extend straight, which is advantageous in reducing the pressure loss of the fluid (W) flowing through the connecting passages (67, 68).

[0140] Providing the sound deadening material (96) in the discharge pipes (95, 98) is advantageous in suppressing noise caused by the fluid (W) flowing through the discharge pipes (95, 98).

[0141] The retaining member (77) that presses the rear bearing holder (73) in the axial direction (X) is plate-shaped with its thickness direction (t) coinciding with the axial direction (X), which is advantageous in reducing the dimension of the screw compressor (1) in the axial direction (X).

[0142] The apparent volumes of the compression chambers (S1, S2) can be easily adjusted by adjusting the opening (C) of the discharge ports (S1, S2) with the slide valves (87, 89).

[0143] Since the first case side discharge port (63) and the second case side discharge port (64) are located at different positions from each other in the circumferential direction (θ), both the first case side discharge port (63) and the second case side discharge port (64) can be positioned between the first position (Ka) and the second position (Kb) in the axial direction (X) without interfering with each other.

[0144] Since the first compression chamber (S1) and the second compression chamber (S2) are spaced apart from each other in the radial direction (R) rather than in the axial direction (X), this is advantageous in reducing the axial (X) dimension of the screw compressor (1). In addition to the above configuration, since the case-side discharge port (63, 64) and the discharge port (65, 66) are hardly spaced apart from each other in the axial direction (X), this is more advantageous in reducing the axial (X) dimension of the screw compressor (1).

[0145] When two or more case-side discharge ports (63, 64) are provided, there is a large cost advantage in adopting the above configuration compared to when there is only one case.

[0146] Since the screw compressor (1) is a two-stage screw compressor, the fluid (W) can be compressed in two stages by the first compression chamber (S1) and the second compression chamber (S2).

[0147] <Second embodiment> A screw compressor (1) according to a second embodiment will be described. In the following description of the second embodiment, the same components as those in the above embodiment will be given the same reference numerals, and detailed description thereof may be omitted. Fig. 13 is a view corresponding to Fig. 3 according to the second embodiment, and shows the screw compressor (1) in a front view.

[0148] In this embodiment, the screw compressor (1) is not a two-stage compressor. The first discharge pipe (95) and the second discharge pipe (98) join together at a junction (99). One end of a junction pipe (100) is connected to the junction (99). The first discharge pipe (95) and the second discharge pipe (98) communicate with the junction pipe (100) at the junction (99). The other end of the junction pipe (100) is connected to, for example, a condenser in the refrigerant circuit.

[0149] The pulsation (U) of the fluid (W) flowing from the first discharge port (65) through the first connection passage (67), the first case side discharge outlet (63), the first cap side discharge passage (94), and the first discharge pipe (95) to the junction (99) and the pulsation (U) of the fluid (W) flowing from the second discharge port (66) through the second connection passage (68), the second case side discharge outlet (64), the second cap side discharge passage (97), and the second discharge pipe (98) to the junction (99) cancel each other out.

[0150] In order to cancel out the pulsations (U) of the fluids (W) with each other, the pulsations (U) of the fluids (W) are made to have opposite phases to each other.

[0151] In order to cancel out the pulsations (U) of the fluids (W) (to have opposite phases), the opening (C) of the discharge ports (65, 66), the length and diameter of the connecting paths (67, 68), the diameter of the case-side discharge ports (63, 64), the length and diameter of the cap-side discharge paths (94, 97), and the length and diameter of the discharge pipes (95, 98), etc., are adjusted.

[0152] The first discharge pipe (95) is provided with a sound absorbing material (96). The second discharge pipe (98) is provided with a sound absorbing material (96). The junction pipe (100) is provided with a sound absorbing material (96).

[0153] The other configurations are similar to those of the first embodiment.

[0154] This embodiment is advantageous in suppressing noise and vibration caused by the pulsation (U) of the fluid (W).

[0155] <Third embodiment> A screw compressor (1) according to a third embodiment will be described. In the following description of the third embodiment, the same components as those in the above-described embodiment will be denoted by the same reference numerals, and detailed description thereof may be omitted. Fig. 14 shows the cap-side discharge passage (94, 97) according to the third embodiment.

[0156] The cap-side discharge passage (94, 97) includes a hole portion (94a, 97a), a pipe portion (94b, 97b), and a cap-side insertion pipe (94c, 97c). The cap-side insertion pipe (94c, 97c) of the cap-side discharge passage (94, 97) is located on the inner periphery side (Rb) of the cap (91, 93) in the radial direction (R) and extends in the radial direction (R).

[0157] The cap side insertion pipe (94c, 97c) is inserted into the inner diameter of the case side discharge port (63, 64). An O-ring (101) serving as a second seal member is provided on the outer periphery of the cap side insertion pipe (94c, 97c). The case side discharge port (63, 64) and the cap side insertion pipe (94c, 97c) are sealed by the O-ring (101).

[0158] The other configurations are similar to those of the first embodiment.

[0159] According to this embodiment, it is possible to prevent the fluid (W) discharged from the case-side discharge port (63, 64) from leaking to the outside before reaching the cap-side discharge path (94, 97).

[0160] <Other embodiments> The case side discharge ports (63, 64) do not have to be positioned so as to overlap with the discharge ports (65, 66) in the axial direction (X), and may be shifted in the axial direction (X) relative to the discharge ports (65, 66) within a range between a front position (Ka) and a rear position (Kb).

[0161] The caps (91, 93) and the cap-side discharge passages (94, 97) do not have to be integrally formed, but may be formed as separate members.

[0162] The case-side discharge openings (63, 64) may be located at positions different from the gate openings (60, 62). The case-side discharge openings (63, 64) do not need to be covered with the caps (91, 93).

[0163] The connection paths (67, 68) do not have to extend straight, and may be bent midway in the axial direction (X), radial direction (R), or circumferential direction (θ).

[0164] A cover may be used in place of the plate-shaped holding member (77).

[0165] The first case side discharge port (63) and the second case side discharge port (64) may be located at the same position in the circumferential direction (θ) as long as they fall within the range between a front position (Ka) and a rear position (Kb) in the axial direction.

[0166] In the above embodiment, two compression chambers, the first compression chamber (S1) and the second compression chamber (S2), are provided, but this is not limiting. The number of compression chambers may be one, or three or more.

[0167] Although the embodiments have been described above, it will be understood that various modifications of form and details are possible without departing from the spirit and scope of the claims. Elements of the above-mentioned embodiments, modifications, and other embodiments may be appropriately combined or substituted. [Explanation of symbols]

[0168] O center axis X-axis direction Xa Front side (first direction side) Xb rear side (second direction side) R Radial direction Ra Outer circumference (outside) Rb Inner circumference side (inside) V vertical direction Va upper side (above) Vb lower side (downward) θ Circumferential direction r Gate radius t thickness direction W Working fluid (fluid) S1 First compression chamber S2 Second compression chamber Sm intermediate chamber P1 First pressure P2 Second pressure Pm Intermediate pressure C Opening degree Ka Front position (1st position) Kb rear position (2nd position) F communication path Fa inclined part Fb bottom edge A Rotating body DA outermost diameter D20 outermost diameter D41 outermost diameter G Oil puddle G0 oil level g oil U pulsation 1. Screw compressor 10 Shaft 20 Screw rotor 21 Screw groove 22 Front rotating seal 23 Rear rotating seal part 30 First Gate Rotor 32 Gate 1 35 Second Gate Rotor 37 Gate 2 40 Motor 41 Motor rotor 42 Motor stator 50 Casing 53 Partition wall (wall) 53b Communication hole 54 Motor Room 55 Cylindrical wall 55a Front fixed seal part (part) 55b Rear fixed seal part (part) 55c part 55d part 56 First Slit 57 Second Slit 58 Case outer wall 58a First case side mounting surface 58b Second case side mounting surface 59 First Gate Rotor Room 60 First Gate Opening 61 Second Gate Rotor Room 62 Second Gate Opening 63 First case side outlet 64 Second case side outlet 65 First discharge port 65a Front end (first end) 65b Rear end (second end) 66 Second discharge port 66a Front end (first end) 66b Rear end (second end) 67 First Connector 68 Second Connector 69a First intake port 69c 2nd intake port 73 Rear bearing holder (bearing holder) 74 Rear bearing (bearing) 77 Retaining member 87 First slide valve 89 Second slide valve 91 1st Cap 92 Gasket (first sealing member) 93 2nd Cap 94 First cap side discharge passage 94c Cap side plug pipe 95 1st discharge pipe 96 Sound deadening material 97 Second cap side discharge passage 97c Cap side insertion tube 98 2nd discharge pipe 99 Junction 100 Confluence pipe 101 O-ring (second seal member)

Claims

1. a screw rotor (20) having a screw groove (21) and extending in an axial direction (X); a gate rotor (30, 35) having a gate (32, 37) that meshes with the screw groove (21); a casing (50) that rotatably holds the screw rotor (20) and covers the screw rotor (20) from an outside (Ra) in a radial direction (R) perpendicular to the axial direction (X), The screw rotor (20), the gate rotors (30, 35), and the casing (50) form compression chambers (S1, S2) for compressing a fluid (W), A case outer wall portion (58) on the outer side (Ra) in the radial direction (R) of the casing (50) is formed with case side discharge ports (63, 64) through which the fluid (W) is discharged, A discharge port (65, 66) communicating with the case-side discharge port (63, 64) is formed in a portion (55c, 55d) of the casing (50) facing the compression chamber (S1, S2), The discharge port (65, 66) includes a first end portion (65a, 66a) on a first direction side (Xa) in the axial direction (X) and a second end portion (65b, 66b) on a second direction side (Xb) opposite to the first direction side (Xa) in the axial direction (X), the case-side discharge port (63, 64) is located, in the axial direction (X), between a first position (Ka) that is spaced from the first end (65a, 66a) in the first direction side (Xa) by a radius (r) of the gate (32, 37) and a second position (Kb) that is spaced from the second end (65b, 66b) in the second direction side (Xb) by the radius (r) of the gate (32, 37); the case-side discharge port (63, 64) is located closer to the discharge port (65, 66) than the screw rotor (20) is in the radial direction (R), The gate rotors (30, 35) are housed in gate rotor chambers (59, 61) provided in the casing (50), The case outer wall portion (58) is provided with gate openings (60, 62) communicating with the gate rotor chambers (59, 61), The case-side discharge port (63, 64) and the gate opening (60, 62) are covered with caps (91, 93), The cap (91, 93) is provided with a cap-side discharge passage (94, 97) communicating with the case-side discharge port (63, 64).

2. the case-side discharge ports (63, 64) are flush with case-side mounting surfaces (58a, 58b) of the case outer wall portion (58) for mounting the caps (91, 93); 2. The screw compressor according to claim 1, wherein the case side mounting surface (58a, 58b) and the cap (91, 93) are sealed with a first seal member (92).

3. the cap-side discharge passage (94, 97) includes a cap-side insertion pipe (94c, 97c) that is inserted into the case-side discharge port (63, 64), 2. The screw compressor according to claim 1, wherein the case-side discharge port (63, 64) and the cap-side insertion pipe (94c, 97c) are sealed by a second seal member (101).

4. 3. The screw compressor according to claim 1, wherein the case-side discharge port (63, 64) is positioned so as to overlap with the discharge port (65, 66) in the axial direction (X).

5. The casing (50) is provided with connection paths (67, 68) that connect the case-side discharge ports (63, 64) and the discharge ports (65, 66), 3. The screw compressor according to claim 1, wherein the connecting passages (67, 68) extend straight.

6. Discharge pipes (95, 98) are connected to the case-side discharge ports (63, 64), 3. The screw compressor according to claim 1, wherein said discharge pipes (95, 98) are provided with sound absorbing material (96).

7. a bearing holder (73) for holding a bearing (74) for supporting the screw rotor (20); a holding member (77) that holds the bearing holder (73) in the axial direction (X), 3. The screw compressor according to claim 1, wherein the retaining member (77) is plate-shaped with a thickness direction (t) aligned in the axial direction (X).

8. 3. The screw compressor according to claim 1, further comprising slide valves (87, 89) adapted to adjust an opening degree (C) of the discharge ports (65, 66) by moving in the axial direction (X).

9. The gate rotors (30, 35) include a first gate rotor (30) and a second gate rotor (35), the screw rotor (20), the first gate rotor (30), and the casing (50) form a first compression chamber (S1) as one of the compression chambers (S1, S2), the screw rotor (20), the second gate rotor (35), and the casing (50) form a second compression chamber (S2) as one of the compression chambers (S1, S2), The case outer wall portion (58) is formed with a first case discharge port (63) and a second case discharge port (64) as the case discharge ports (63, 64), A first discharge port (65) serving as the discharge port (65, 66) is formed in a portion (55c) of the casing (50) facing the first compression chamber (S1), A second discharge port (66) serving as the discharge port (65, 66) is formed in a portion (55d) of the casing (50) facing the second compression chamber (S2), The first discharge port (65) is in communication with the first case-side discharge port (63), The second discharge port (66) is in communication with the second case-side discharge port (64), 3. The screw compressor according to claim 1, wherein the first case side discharge port (63) and the second case side discharge port (64) are located at different positions from each other in a circumferential direction (θ) of the screw rotor (20).

10. The gate rotors (30, 35) include a first gate rotor (30) and a second gate rotor (35), the screw rotor (20), the first gate rotor (30), and the casing (50) form a first compression chamber (S1) as one of the compression chambers (S1, S2), the screw rotor (20), the second gate rotor (35), and the casing (50) form a second compression chamber (S2) as one of the compression chambers (S1, S2), The case outer wall portion (58) is formed with a first case discharge port (63) and a second case discharge port (64) as the case discharge ports (63, 64), A first discharge port (65) serving as the discharge port (65, 66) is formed in a portion (55c) of the casing (50) facing the first compression chamber (S1), A second discharge port (66) serving as the discharge port (65, 66) is formed in a portion (55d) of the casing (50) facing the second compression chamber (S2), The first discharge port (65) is in communication with the first case-side discharge port (63), The second discharge port (66) is in communication with the second case-side discharge port (64), A first discharge pipe (95) is connected to the first case-side discharge port (63), A second discharge pipe (98) is connected to the second case-side discharge port (64), The first discharge pipe (95) and the second discharge pipe (98) join at a joining portion (99), 3. The screw compressor according to claim 1, wherein a pulsation (U) of the fluid (W) traveling from the first discharge port (65) to the junction (99) via the first case side discharge port (63) and the first discharge pipe (95) and a pulsation (U) of the fluid (W) traveling from the second discharge port (66) to the junction (99) via the second case side discharge port (64) and the second discharge pipe (98) are configured to cancel each other out.

11. The first compression chamber (S1) compresses the fluid (W) at a first pressure (P1) to an intermediate pressure (Pm) higher than the first pressure (P1), The second compression chamber (S2) compresses the fluid (W) at the intermediate pressure (Pm) to a second pressure (S2) that is higher than the intermediate pressure (Pm), 10. The screw compressor according to claim 9, wherein the fluid (W) flows through the first compression chamber (S1), the first discharge port (65), the first case side discharge port (63), the second compression chamber (S2), the second discharge port (66), and the second case side discharge port (64), in this order.

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