Screw compressors and refrigeration equipment

Abstract

To prevent performance deterioration from occurring in a screw compressor.SOLUTION: A screw compressor comprises a screw rotor (40), a plurality of gate rotors (50, 60), a casing (10) having a cylindrical wall (15), and an adjustment mechanism. A plurality of compression chambers are formed inside the cylindrical wall (15) by the screw rotor (40) and gates (51, 61). The plurality of compression chambers include a first compression chamber (21) and a second compression chamber (22) to which fluid compressed in the first compression chamber (21) is sent via an intermediate pressure space (S). The adjustment mechanism adjusts an intermediate pressure, which is a pressure of fluid in the intermediate pressure space (S), during two-stage operation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a screw compressor. The screw compressor of Patent Document 1 switches between two-stage operation and single-stage operation by moving a high-stage slide valve in a two-stage screw compressor in the direction of the rotation axis. The high-stage compression chamber has two outlets. When the slide valve is positioned on the power source side, it closes the first fluid outlet and transports refrigerant out of the compressor through the second fluid outlet. On the other hand, when the high-stage slide valve is positioned on the reaction source side, it opens the first fluid outlet and transports refrigerant out of the compressor through the first fluid outlet. In other words, when the slide valve is positioned on the power source side, two-stage compression is performed, and when it is positioned on the reaction source side, refrigerant is not compressed in the high-stage compression chamber, enabling single-stage operation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] China Publication No. 109667760 Summary of the Invention [Problem to be solved by the invention]

[0004] However, during two-stage operation, which requires a high compression ratio, the suction pressure (intermediate pressure) to the higher-stage compression chamber (second compression chamber) is determined by the volume ratio between the lower-stage compression chamber and the higher-stage compression chamber. The screw compressor described in Patent Document 1 achieves high performance when its own intermediate pressure matches the ideal intermediate pressure, but performance degradation occurs when the operating state deviates from the designed internal volume ratio. The screw compressor described in Patent Document 1 cannot adjust the intermediate pressure, so it is difficult to suppress performance degradation of the screw compressor when its own intermediate pressure differs from the ideal intermediate pressure.

[0005] An object of the present disclosure is to provide a screw compressor that can suppress the occurrence of performance degradation. [Means for solving the problem]

[0006] The screw compressor of the first aspect includes a screw rotor (40), a plurality of gate rotors (50, 60) having gates (51, 61) meshing with the screw rotor (40), a casing (10) having a cylindrical wall (15) into which the screw rotor (40) is rotatably inserted and through which the gates (51, 61) penetrate, and an adjusting mechanism for adjusting the pressure of a fluid in the casing (10). , 61) form a plurality of compression chambers, and the plurality of compression chambers include a first compression chamber (21) that compresses a fluid at a suction pressure introduced into the casing (10) to a pressure higher than the suction pressure, and a second compression chamber (22) to which the fluid compressed in the first compression chamber (21) is sent via an intermediate pressure space (S), and the adjustment mechanism is capable of adjusting the intermediate pressure, which is the pressure of the fluid in the intermediate pressure space (S), during two-stage operation in which the fluid is compressed in the first compression chamber (21) and the second compression chamber (22).

[0007] In the first aspect, it is possible to suppress the occurrence of a performance degradation in the screw compressor.

[0008] In the second aspect, in the first aspect, the adjustment mechanism includes a valve (80) that is movable in an opposing area that indicates a rotor space surrounded by the gate rotors (50, 60) and the screw rotor (40), and the valve (80) changes its position within the opposing area (V) to change the timing at which the second compression chamber (22) is fully closed.

[0009] In the second aspect, when the valve (80) is located in the opposing region (V), the second compression chamber (22) is formed, and the fluid can be compressed in the second compression chamber (22). The intermediate pressure can be adjusted to a desired value (ideal value) by changing the timing at which the second compression chamber (22) is fully closed by the valve (80).

[0010] In the third aspect, in the second aspect, the valve (80) changes the timing at which the second compression chamber (22) is fully closed, thereby changing the volume of the second compression chamber (22) at the start of the compression process of the fluid in the second compression chamber (22).

[0011] In the third aspect, by changing the volume of the second compression chamber (22), the amount of fluid sent from the intermediate pressure space (S) to the second compression chamber (22) can be limited to an amount corresponding to the volume of the second compression chamber (22) immediately after it is fully closed, thereby making it possible to effectively adjust the intermediate pressure.

[0012] In a fourth aspect, in the second or third aspect, the valve (80) switches between a single-stage operation in which the fluid is compressed in the first compression chamber (21) of the first compression chamber (21) and the second compression chamber (22), and the two-stage operation.

[0013] In the fourth embodiment, the valve (80) can be used to switch between single-stage operation and two-stage operation.

[0014] In the fifth aspect, in the fourth aspect, the valve (80) is movable to a separated position (W) separated from the rotor space, and when positioned at the separated position (W), the intermediate pressure space (S) is maintained in communication with the outside of the aircraft.

[0015] In the fifth aspect, when the valve (80) is in the separated position (W), the second compression chamber (22) is maintained in communication with the outside of the machine, and the refrigerant compressed in the first compression chamber (21) can be discharged outside the machine without being further compressed.

[0016] In a sixth aspect, in the fifth aspect, a first passage (91) and a second passage (92) communicating with the intermediate pressure space (S) are provided inside the casing (10), and when the valve (80) is located in the opposing region (V), the valve (80) sends fluid from the intermediate pressure space (S) to the second compression chamber (22) through the first passage (91) and sends fluid that has not entered the second compression chamber (22) because the second compression chamber (22) is in a closed state to the intermediate pressure space (S) through the second passage (92).When the valve (80) is located in the separated position (W), the valve (80) sends fluid from the intermediate pressure space (S) to the outside of the aircraft through the first passage (91) and sends fluid from the intermediate pressure space (S) to the outside of the aircraft through the second passage (92).

[0017] In the sixth aspect, when the valve (80) is located in the opposing region (V), the amount of fluid compressed in the second compression chamber (22) can be limited and the intermediate pressure can be adjusted by returning the fluid to the intermediate pressure space (S) through the first passage (91) and the second passage (92). When the valve (80) is located in the separated position (W), the fluid can be smoothly sent to the outside of the machine using the multiple passages (the first passage (91) and the second passage (92)), thereby suppressing pressure loss in the fluid.

[0018] In a seventh aspect, in the fifth or sixth aspect, the two-stage operation is performed when the valve (80) is located in the opposing region (V), the intermediate pressure is adjusted by changing the position of the valve (80) in the opposing region (V), and the single-stage operation is performed when the valve (80) is located at the separated position (W).

[0019] In the seventh aspect, by moving the valve (80), it is possible to switch between single-stage operation and two-stage operation, and further, during two-stage operation, the intermediate pressure can be adjusted. Therefore, it is easy to switch the operation of the screw compressor and adjust the intermediate pressure.

[0020] An eighth aspect is any one of the second to seventh aspects, wherein the position of the valve (80) is continuously changeable, and thereby the timing at which the second compression chamber (22) is fully closed can be continuously adjusted.

[0021] In the eighth aspect, the intermediate pressure can be adjusted with high precision.

[0022] In a ninth aspect, in the sixth aspect, the first passage (91) and the second passage (92) are located on one side (J1) of the movement direction (J) of the valve (80) relative to the separated position (W), and the one side (J1) of the movement direction (J) indicates the direction from the separated position (W) toward the opposing region (V) in the movement direction (J) of the valve (80).

[0023] In the ninth aspect, the first passage (91) and the second passage (92) can be spaced apart from the separated position (W) of the valve (80) in the movement direction (J) of the valve (80).

[0024] In a tenth aspect, in the sixth or ninth aspect, the valve (80) includes an end face (82) located on one side (J1) of the movement direction (J) of the valve (80), the second passage (92) is disposed opposite the end face (82), and the one side (J1) of the movement direction (J) indicates the direction from the separated position (W) toward the opposing region (V) in the movement direction (J) of the valve (80).

[0025] In the tenth aspect, the position of the valve (80) can be switched between a position in the facing region (V) or a separated position (W) by moving the valve (80) closer to or away from the second passage (92).

[0026] An eleventh aspect is any one of the sixth, ninth and tenth aspects, wherein the first passage (91) includes a first opening (91a) that leads to the second compression chamber (22), the second passage (92) includes a second opening (92a) that leads to the second compression chamber (22), and the second opening (92a) is located at a lower position than the first opening (91a).

[0027] In the eleventh aspect, oil can be prevented from accumulating inside the machine.

[0028] A twelfth aspect is the sixth aspect or any one of the ninth to eleventh aspects, wherein the second passage (92) extends along the axis (N) of the valve (80).

[0029] In a twelfth embodiment, the valve (80) and the second passage (92) can be arranged in a straight line.

[0030] A refrigeration device according to a thirteenth aspect includes the screw compressor according to any one of the first to twelfth aspects.

[0031] In the thirteenth aspect, it is possible to suppress the occurrence of a performance degradation in the screw compressor. [Brief explanation of the drawings]

[0032] [Figure 1] FIG. 1 is a refrigerant circuit diagram showing the configuration of a refrigeration device. [Figure 2] FIG. 2 is a cross-sectional view of the screw compressor as viewed from the rear side. [Figure 3] FIG. 3 is a side cross-sectional view showing the configuration of the screw compressor. [Figure 4] FIG. 4 is a perspective view showing the configuration of the compression mechanism. [Figure 5] FIG. 5 is a plan view showing the spiral groove on the lower stage side. [Figure 6] FIG. 6 is a plan view showing the spiral groove on the high stage side. [Figure 7] FIG. 7 is a plan view showing the suction stroke of the screw compressor. [Figure 8] FIG. 8 is a plan view showing the compression stroke of the screw compressor. [Figure 9] FIG. 9 is a plan view showing the discharge stroke of the screw compressor. [Figure 10] FIG. 10 is a cross-sectional perspective view of a screw compressor. [Figure 11] FIG. 11 is a cross-sectional perspective view of a screw compressor. [Figure 12] FIG. 12 is a plan view showing the intermediate pressure space. [Figure 13] FIG. 13 is a perspective view showing the second slide valve. [Figure 14] FIG. 14 is a cross-sectional perspective view showing the second slide valve positioned in the opposing region. [Figure 15] FIG. 15 is a cross-sectional perspective view showing the second slide valve positioned in the opposing region. [Figure 16] FIG. 16 is a cross-sectional perspective view showing the second slide valve in the separated position. DETAILED DESCRIPTION OF THE INVENTION

[0033] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments shown below, and various modifications are possible within the scope of the technical concept of the present disclosure. Since each drawing is intended to conceptually explain the present disclosure, dimensions, ratios, or numbers may be exaggerated or simplified as necessary to facilitate understanding. In each embodiment, modified example, and drawing, the same or equivalent parts are designated by the same reference symbols, and detailed descriptions and descriptions of the accompanying effects will not be repeated.

[0034] -Refrigeration equipment- As shown in FIG. 1, the refrigeration system (2) has a refrigerant circuit (2a) filled with a refrigerant. The refrigerant circuit (2a) has a screw compressor (1), a radiator (3), a pressure reduction mechanism (4), and an evaporator (5). The pressure reduction mechanism (4) is, for example, an expansion valve. The refrigerant circuit (2a) performs a vapor compression refrigeration cycle. In the refrigeration cycle, the refrigerant compressed by the screw compressor (1) dissipates heat into the air by the radiator (3). The refrigerant that has dissipated heat is reduced in pressure by the pressure reduction mechanism (4) and evaporated by the evaporator (5). The evaporated refrigerant is drawn into the screw compressor (1). The refrigerant contains lubricating oil that lubricates the sliding parts of the screw compressor (1). The refrigerant is an example of a fluid.

[0035] The refrigeration system (2) is an air conditioner. The air conditioner may be a dedicated cooling system, a dedicated heating system, or an air conditioner that switches between cooling and heating. In this case, the air conditioner has a switching mechanism (e.g., a four-way switching valve) that switches the refrigerant circulation direction. The refrigeration system (2) may be a water heater, a chiller unit, a cooling device that cools the air inside a storage unit, or the like. A cooling device cools the air inside a refrigerator, a freezer, a container, or the like.

[0036] -Screw compressor- 2 and 3, the screw compressor 1 includes a casing 10 and a compression mechanism 20. The casing 10 accommodates the compression mechanism 20. The compression mechanism 20 is connected to an electric motor (not shown) via a drive shaft 25.

[0037] The compression mechanism (20) includes a cylindrical wall (15) provided in the casing (10), one screw rotor (40), a first rotor (31), and a second rotor (32).

[0038] The screw rotor (40) is a metal member formed into a generally cylindrical shape. The outer diameter of the screw rotor (40) is set to be slightly smaller than the inner diameter of the cylindrical wall (15). The outer peripheral surface of the screw rotor (40) is close to the inner peripheral surface of the cylindrical wall (15). The screw rotor (40) is rotatably inserted into the casing (10).

[0039] As shown in FIGS. 3 to 6, a plurality of spiral grooves (41) extending spirally are formed on the outer periphery of the screw rotor (40). The spiral grooves (41) extend from one side (J1) to the other side (J2) in the axial direction (J) of the screw rotor (40). The axial direction (J) is the direction in which the rotation axis of the screw rotor (40) extends. The screw rotor (40) has a first end (42) and a second end (43) at both ends in the axial direction (J). The first end (42) and the second end (43) each have a smooth cylindrical outer periphery 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). A drive shaft (25) is connected to the screw rotor (40). The drive shaft 25 and the screw rotor 40 rotate together. The axial direction J is an example of the direction of movement of the valve 80.

[0040] As shown in FIGS. 2 and 5, the first rotor (31) is configured as a first gate rotor (50). The first gate rotor (50) has first gates (51) which are a plurality of radially arranged teeth. The first gates (51) mesh with the helical grooves (41) of the screw rotor (40). The first gate rotor (50) is housed in a first gate rotor chamber (17). The first gate rotor chamber (17) is defined within the casing (10) and is adjacent to the cylindrical wall (15).

[0041] As shown in FIGS. 2 and 6, the second rotor (32) is configured as a second gate rotor (60). The second gate rotor (60) has second gates (61) which are a plurality of radially arranged teeth. The second gates (61) mesh with the helical grooves (41) of the screw rotor (40). The second gate rotor (60) is housed in a second gate rotor chamber (18). The second gate rotor chamber (18) is defined within the casing (10) and is adjacent to the cylindrical wall (15). The gates (51, 61) penetrate the cylindrical wall (15).

[0042] As shown in Figures 2 and 3, a plurality of compression chambers are formed inside the cylindrical wall (15) by the screw rotor (40) and the gates (51, 61). In this embodiment, a first compression chamber (21) and a second compression chamber (22) are formed inside the cylindrical wall (15). The first compression chamber (21) is a space surrounded by the helical groove (41) of the screw rotor (40) and the first gate (51) of the first gate rotor (50). The second compression chamber (22) is a space surrounded by the helical groove (41) of the screw rotor (40) and the second gate (61) of the second gate rotor (60).

[0043] The first compression chamber (21) is in communication with a discharge side thereof through a first discharge pipe (7). An intermediate pressure space (S) is formed inside the casing (10). The intermediate pressure space (S) is a space in which the electric motor for driving the screw rotor (40) to rotate is disposed. The intermediate pressure space (S) is in communication with a suction side thereof through a suction pipe (8). The first discharge pipe (7) and the suction pipe (8) are in communication with each other through a connecting pipe (not shown) or the like. The intermediate pressure space (S) is in communication with the second compression chamber (22) through a plurality of passages (a first passage (91) and a second passage (92)) described below. The second discharge pipe (9) is in communication with a discharge side thereof through a second discharge pipe (9). The second discharge pipe (9) is in communication with the outside of the machine (the outside of the screw compressor (1)). A wall (19) is provided inside the casing (10) to separate the intermediate pressure space (S) from a space in which the screw rotor (40) is installed.

[0044] As shown in Fig. 3, the screw compressor (1) is provided with a first slide valve (70) and a second slide valve (80). The first slide valve (70) and the second slide valve (80) are each housed in a valve housing portion (16a, 16b) in which the cylindrical wall (15) bulges outward in the radial direction of the screw rotor (40) at two circumferential positions (see Fig. 2). The second slide valve (80) is an example of an adjustment mechanism.

[0045] Each of the first slide valve (70) and the second slide valve (80) is configured to be slidable along the axial direction (J). Each of the first slide valve (70) and the second slide valve (80) faces the outer circumferential surface of the screw rotor (40) when inserted into the valve storage portion (16). The screw compressor (1) is provided with a drive mechanism (28) for slidingly driving the first slide valve (70) and the second slide valve (80).

[0046] The drive mechanism (28) includes a first electric motor that slides (moves) the first slide valve (70) and a second electric motor that slides the second slide valve (80). The rotational motion of the first electric motor is converted into linear motion by gears, thereby moving the first slide valve (70) along the axial direction (J). The first electric motor includes, for example, a stepping motor, and is capable of continuously changing its rotation speed. The ability to continuously change the rotational speed of the first electric motor means that the rotational speed (rotation angle) of the first electric motor can be continuously changed (changeable in small intervals). The rotational motion of the second electric motor is converted into linear motion by gears, thereby moving the second slide valve (80) along the axial direction (J). The second electric motor includes, for example, a stepping motor, and is capable of continuously changing its rotational speed. The ability to continuously change the rotational speed of the second electric motor means that the rotational speed (rotation angle) of the second electric motor can be continuously changed (changeable in small intervals).

[0047] Each of the first slide valve (70) and the second slide valve (80) is a valve whose position in the axial direction (J) can be adjusted. The first slide valve (70) can be used as an unloading mechanism that returns refrigerant being compressed in the first compression chamber (21) to the suction side to change the operating capacity. The first slide valve (70) can be used as a compression ratio adjustment mechanism that adjusts the compression ratio (internal volume ratio) of the first compression chamber (21) by adjusting the timing of discharging refrigerant from the first compression chamber (21). The second slide valve (80) can be used as an unloading mechanism that returns refrigerant being compressed in the second compression chamber (22) to the suction side to change the operating capacity. The second slide valve (80) can be used as a compression ratio adjustment mechanism that adjusts the compression ratio (internal volume ratio) of the second compression chamber (22) by adjusting the timing of discharging refrigerant from the second compression chamber (22).

[0048] The screw compressor (1) includes a storage unit and a control unit. The storage unit includes memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory) and stores various computer programs executed by the control unit. The control unit includes a processor such as a CPU and an MPU. The control unit controls each component of the screw compressor (1) (the electric motor, the first electric motor, the second electric motor, etc.) by executing the computer programs stored in the storage unit.

[0049] -First and second compression chambers- The first compression chamber (21) is a compression chamber on the lower stage of the two-stage compression, and compresses the refrigerant at suction pressure introduced into the casing (10) to a pressure higher than the suction pressure. The second compression chamber (22) is a compression chamber on the higher stage of the two-stage compression, and compresses the refrigerant compressed in the first compression chamber (21) to a discharge pressure which is higher.

[0050] 2 and 3, a low-pressure pipe (6) through which a low-pressure refrigerant (a fluid at a suction pressure) flows is connected 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).

[0051] The low-pressure refrigerant is compressed in the first compression chamber (21). The refrigerant compressed in the first compression chamber (21) is supplied to the intermediate-pressure space (S) through the first discharge pipe (7) and the suction pipe (8), and then supplied to the second compression chamber (22) through the second gate rotor chamber (18).

[0052] The high-pressure refrigerant compressed in the second compression chamber (22) and then discharged to the outside of the machine through the second discharge pipe (9). The refrigerant discharged to the outside of the machine through the second discharge pipe (9) circulates through the refrigerant circuit (2a). In this manner, the low-pressure space (S1), the first compression chamber (21), the intermediate-pressure space (S), and the second compression chamber (22) are connected in this order from the side with the lowest fluid pressure to the side with the highest fluid pressure.

[0053] - Driving operation - <Suction, compression, and discharge strokes> 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, whereby in the compression mechanism (20), a suction stroke, a compression stroke, and a discharge stroke are continuously and repeatedly performed in the first compression chamber (21).

[0054] During the suction stroke shown in Fig. 7, the shaded first compression chamber (21) communicates with the space on the suction side. 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 end of the spiral groove (41), thereby increasing the volume of the first compression chamber (21). As a result, the refrigerant is sucked into the first compression chamber (21).

[0055] When the screw rotor (40) rotates further, the compression stroke shown in FIG. 8 is performed. During the compression stroke, the shaded first compression chamber (21) is fully closed. 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 axial position (J) of the first slide valve (70) is changed, the timing at which the first compression chamber (21) is fully closed changes. As the screw rotor (40) rotates, the first gate (51) approaches the end of the spiral groove (41), and the volume of the first compression chamber (21) gradually decreases. As a result, the refrigerant in the first compression chamber (21) is compressed.

[0056] As the screw rotor (40) rotates further, a discharge stroke shown in FIG. 9 is performed. During the discharge stroke, the shaded first compression chamber (21) communicates with the first discharge pipe (7) through the discharge-side end (the end on the right side in the figure). As the screw rotor (40) rotates, the first gate (51) approaches the end of the spiral groove (41), and the compressed refrigerant is forced out of the first compression chamber (21) through the first discharge pipe (7). The forced-out refrigerant is sent to the intermediate-pressure space (S) through the suction pipe (8).

[0057] The suction stroke, compression stroke, and discharge stroke of the second compression chamber (22) on the higher stage side will be described later.

[0058] - Second slide valve and its peripheral configuration - 11 and 12 are partially cutaway cross-sectional views of the screw compressor (1). The screw rotor (40), the second gate rotor (60), the second slide valve (80), and the like are omitted from FIGS. 11 and 12. As shown in FIGS. 11 and 12, the valve housing portion (16b) is provided on the outer periphery of the cylindrical wall (15) and extends along the axial direction (J). The inner periphery of the valve housing portion (16b) has an arc shape that conforms to the outer periphery of the second slide valve (80). The valve housing portion (16b) is provided from a position facing the second compression chamber (22) to a position not facing the second compression chamber (22) (a position spaced apart from the second compression chamber (22)). Facing the second compression chamber (22), in particular, means facing the second compression chamber (22) from the radially outer side of the screw rotor (40). The radial direction of the screw rotor (40) is a direction that passes through the rotation axis (center of rotation) of the screw rotor (40) and is perpendicular to the axial direction (J). The radially outer direction is a radial direction that moves away from the rotation axis of the screw rotor (40). The second discharge pipe (9) has an opening (9a) on the inner circumferential surface of the valve housing portion (16b).

[0059] As shown in FIGS. 10 to 12, a first passage (91) and a second passage (92) are provided inside the casing (10). The first passage (91) and the second passage (92) each communicate with the second gate rotor chamber (18) (the second compression chamber (22)) and the intermediate pressure space (S). The first passage (91) has an opening (91a) in the inner circumferential surface of the cylindrical wall (15). The opening (91a) of the first passage (91) is located opposite the second compression chamber (22). The second passage (92) has an opening (92a) in the end surface of the valve housing portion (16b) on one side (J1) in the axial direction (J). The opening (92a) of the second passage (92) is located lower than the opening (91a) of the first passage (91). The lower position refers to the lower side in the vertical direction. This makes it possible to prevent oil from accumulating inside the screw compressor (1).

[0060] As shown in FIG. 14, the first passage (91) and the second passage (92) are located on one side (J1) in the axial direction (J) relative to the separated position (W).

[0061] The second slide valve (80) includes an end face (82) located on one side (J1) in the axial direction (J). A second passage (92) is disposed opposite the end face (82).

[0062] A second passage (92) is located on the axis (N) of the second slide valve (80). The second passage (92) extends along the axis (N) of the second slide valve (80). The axis (N) of the second slide valve (80) is an imaginary line that passes through the center of the second slide valve (80) and extends in the direction of movement (axial direction (J)) of the second slide valve (80).

[0063] Fig. 13 is an end view of the intermediate-pressure space (S) as viewed from one side (J1) in the axial direction (J). As shown in Fig. 13, the wall portion (19) is provided with an opening (91b) of the first passage (91) and an opening (92b) of the second passage (92). The first passage (91) is an internal passage of the tubular member formed from the opening (91a) to the opening (91b). The second passage (92) is an internal passage of the tubular member formed from the opening (92a) to the opening (92b).

[0064] 14 is a perspective view showing the second slide valve (80). The second slide valve (80) is provided with a fluid passage (81). The fluid passage (81) is a notch formed in the second slide valve (80).

[0065] As shown in FIG. 10, the second slide valve (80) is movable between a facing region (V) and a separated position (W).

[0066] -Opposing area- 14 and 15 show the second slide valve (80) located in the opposing region (V). As shown in FIGS. 10, 14, and 15, the opposing region (V) is a region that indicates a rotor space, and is a region in which the timing at which the second compression chamber (22) is fully closed can be changed. The rotor space is a space surrounded by the gate rotors (50, 60) and the screw rotor (40). The rotor space is a space surrounded by the gate rotors (50, 60) and the outer surface of the screw rotor (40) on the side where the second compression chamber (22) is formed. The rotor space is, for example, a space surrounded by the gate rotors (50, 60) along the rotation direction of the screw rotor (40). When the second slide valve (80) is located in the opposing region (V), the fluid passage (81) (see FIG. 13) of the second slide valve (80) faces the opening (9a) of the second discharge pipe (9). When the second slide valve (80) is located in the opposing region (V), the screw compressor (1) performs two-stage operation, in which the refrigerant is compressed in the first compression chamber (21) and the second compression chamber (22).

[0067] -Two-stage operation- When the second slide valve (80) is located in the opposing region (V), the second compression chamber (22) communicates with the first passage (91) during the suction stroke (see FIGS. 6 and 7). The spiral groove (41) corresponding to the second compression chamber (22) meshes with the second gate (61) of the second gate rotor (60). When the screw rotor (40) rotates, the second gate (61) moves relatively toward the end of the spiral groove (41), thereby increasing the volume of the second compression chamber (22). As a result, the refrigerant in the intermediate-pressure space (S) (refrigerant compressed in the first compression chamber (21)) is sucked into the second compression chamber (22) through the first passage (91).

[0068] When the screw rotor (40) rotates further, a compression stroke is performed (see FIGS. 6 and 8). During the compression stroke, the second compression chamber (22) is closed off. That is, the spiral groove (41) corresponding to the second compression chamber (22) is separated from the suction-side space by the second gate (61). The refrigerant that has been sent from the intermediate-pressure space (S) through the first passage (91) to the second compression chamber (22) (see arrow Z1 in FIG. 11) and that has not entered the second compression chamber (22) because the second compression chamber (22) is closed off is sent to the intermediate-pressure space (S) through the second passage (92) (see arrow Z2 in FIGS. 14 and 15). As the screw rotor (40) rotates, the second gate (61) approaches the end of the spiral groove (41), and the volume of the second compression chamber (22) gradually decreases. As a result, the refrigerant in the second compression chamber (22) is compressed to a discharge pressure.

[0069] When the screw rotor (40) rotates further, a discharge stroke is performed (see FIGS. 6 and 9). During the discharge stroke, the second compression chamber (22) faces the fluid passage (81) of the second slide valve (80) through the discharge end, and is thereby connected to the second discharge pipe (9) through the fluid passage (81) and the opening (9a). As the screw rotor (40) rotates, the second gate (61) approaches the end of the spiral groove (41), and the compressed refrigerant (refrigerant at discharge pressure) is forced out of the machine from the second compression chamber (22) through the fluid passage (81) and the second discharge pipe (9) (see arrow Z3 in FIGS. 14 and 15).

[0070] When the second slide valve (80) is located in the opposing region (V), the compression mechanism (20) continuously and repeatedly performs the suction stroke, compression stroke, and discharge stroke in the second compression chamber (22).

[0071] As described above, when the second slide valve (80) is located in the opposing region (V), the screw compressor (1) discharges refrigerant that has been compressed in the first passage (91) and then in the second compression chamber (22), thereby performing two-stage operation.

[0072] - Timing of closing the second compression chamber during two-stage operation - Hereinafter, the pressure of the refrigerant in the intermediate pressure space (S) may be referred to as intermediate pressure.

[0073] 10, 14, and 15, the position of the second slide valve (80) in the opposing region (V) is changed, thereby changing the timing at which the second compression chamber (22) is fully closed during the compression stroke. In this embodiment, the closer the second slide valve (80) is positioned in the opposing region (V) to one side (J1) in the axial direction (J), the earlier the timing at which the second compression chamber (22) is fully closed. The earlier the timing at which the second compression chamber (22) is fully closed, the larger the volume of the second compression chamber (22) at the start of the compression stroke of the fluid in the second compression chamber (22). As the volume of the second compression chamber (22) increases at the start of the fluid compression process in the second compression chamber (22), the amount of refrigerant returned to the intermediate pressure space (S) through the second passage (92) decreases (see arrow Z2 in FIGS. 14 and 15) from the intermediate pressure space (S) through the first passage (91) sent to the second compression chamber (22) (see arrow Z1 in FIG. 11).

[0074] As described above, by changing the position of the second slide valve (80) in the opposing region (V), the timing at which the second compression chamber (22) is fully closed is changed, and thus the volume of the second compression chamber (22) at the start of the compression process (immediately after the second compression chamber (22) is fully closed) is changed. As a result, if the volume of the second compression chamber (22) at the start of the compression process is reduced, smooth discharge of the refrigerant through the intermediate pressure space (S), the second compression chamber (22), and the second discharge pipe (9) is suppressed, and therefore the intermediate pressure increases. On the other hand, if the volume of the second compression chamber (22) at the start of the compression process is increased, smooth discharge of the refrigerant through the intermediate pressure space (S), the second compression chamber (22), and the second discharge pipe (9) is suppressed, and therefore the increase in the intermediate pressure is suppressed. As a result, by changing the position of the second slide valve (80) in the opposing region (V), the intermediate pressure is adjusted.

[0075] As described above, the rotation speed of the second electric motor can be continuously changed, and therefore, the position of the second slide valve (80) in the axial direction (J) can be continuously changed (changed in small intervals), and therefore, the timing at which the second compression chamber (22) is completely closed can be continuously adjusted (the timing can be finely adjusted).

[0076] -Separate position- Fig. 16 shows the second slide valve (80) in the separated position (W). The separated position (W) is a position where the second slide valve (80) is separated from the rotor space. As shown in Figs. 10 and 16, when the second slide valve (80) is in the separated position (W), the screw compressor (1) performs single-stage operation. The single-stage operation is an operation in which the refrigerant is compressed only in the first compression chamber (21) out of the first compression chamber (21) and the second compression chamber (22).

[0077] -Single stage operation- When the second slide valve (80) is in the separated position (W), the second slide valve (80) is separated from the second compression chamber (22), which prevents the second compression chamber (22) from being fully closed by the second slide valve (80). This prevents the refrigerant from being compressed by the second compression chamber (22).

[0078] When the second slide valve (80) is in the separated position (W), the intermediate-pressure space (S) is maintained in communication with the outside of the machine via the first passage (91) and the second discharge pipe (9), and the intermediate-pressure space (S) is maintained in communication with the outside of the machine via the second passage (92) and the second discharge pipe (9). As a result, the fluid in the intermediate-pressure space (S) is sent to the outside of the machine via the first passage (91) (see arrow Z1 in FIG. 11 and arrow Z5 in FIG. 16), and is sent to the outside of the machine via the second passage (92) (see arrows Z4 and Z5 in FIG. 16).

[0079] As described above, when the second slide valve (80) is in the separated position (W), the refrigerant compressed only in the first passage (91) of the first passage (91) and the second compression chamber (22) is discharged from the screw compressor (1), thereby performing single-stage operation.

[0080] -effect- As described above, the second slide valve (80) adjusts the intermediate pressure, which is the pressure of the fluid in the intermediate pressure space (S), during two-stage operation in which the fluid is compressed in the first compression chamber (21) and the second compression chamber (22). In this embodiment, the second slide valve (80) adjusts the timing of closing the second compression chamber (22) (the timing at which the second compression chamber (22) is brought into the fully closed state) and changes the volume ratio between the first compression chamber (21) and the second compression chamber (22) to adjust the intermediate pressure. This makes it possible to switch between single-stage operation and two-stage operation depending on the usage and state of the screw compressor (1). Furthermore, since the intermediate pressure can be adjusted during two-stage operation, the screw compressor (1) can be operated efficiently. Furthermore, adjusting the intermediate pressure during two-stage operation makes it possible to control the intermediate pressure of the screw compressor so that it approaches the ideal intermediate pressure, thereby preventing performance degradation of the screw compressor.

[0081] Furthermore, the operating conditions of the SCOP include low compression ratio conditions such as those of general air conditioning, and therefore two-stage operation causes overcompression and large losses. However, the screw compressor (1) of the present embodiment can achieve both single-stage operation and two-stage operation in which the intermediate pressure is adjustable, and therefore the seasonal efficiency SCOP can be improved.

[0082] In addition, in single-stage operation, the refrigerant is sent to the outside of the compressor not only through the first passage (91) but also through the second passage (92), thereby reducing the pressure loss of the refrigerant along the passages, thereby preventing a decrease in operating efficiency even during high-speed single-stage operation.

[0083] Furthermore, by adjusting the timing of closing the second compression chamber (22), the intermediate pressure can be adjusted to an optimum value. Refrigerant that does not enter the second compression chamber (22) can be returned to the intermediate pressure space (S) through the second passage (92). Furthermore, since it is possible to control the intermediate pressure and switch between single-stage operation and two-stage operation, the seasonal efficiency of the screw compressor (1) can be improved. Furthermore, since the discharge port for the refrigerant processed in the single-stage operation or the two-stage operation is a single discharge port (the discharge port of the second discharge pipe (9)), the structure of the screw compressor (1) can be simplified, and the screw compressor (1) can be provided at low cost.

[0084] -Variations- In this embodiment, the second electric motor slides the second slide valve (80) along the axial direction (J) to change the position of the second slide valve (80). However, the present invention is not limited to this. For example, the screw compressor (1) may include a hydraulic cylinder, and the hydraulic cylinder may slide the second slide valve (80) along the axial direction (J) to change the position of the second slide valve (80). The hydraulic cylinder includes a cylinder, a piston disposed in the cylinder, and a rod connected to the piston. The inside of the cylinder is divided into a first cylinder chamber and a second cylinder chamber by the piston. The tip of the rod protrudes outside the cylinder. The second slide valve (80) is connected to the tip of the rod. By adjusting the amount of hydraulic oil in the first cylinder chamber and the amount of hydraulic oil in the second cylinder chamber, the sliding amount of the rod in the axial direction (J) is continuously adjusted, and as a result, the axial position of the second slide valve (80) is continuously changed. The first slide valve (70) may also be slid in the axial direction (J) by a hydraulic device such as the hydraulic cylinder, thereby changing the position of the first slide valve (70) in the axial direction (J).

[0085] In this embodiment, the second slide valve (80) switches between a single-stage operation in which a fluid is compressed only in the first compression chamber (21) of the first compression chamber (21) and the second compression chamber (22), and a two-stage operation in which a fluid is compressed in both the first compression chamber (21) and the second compression chamber (22). However, the present invention is not limited to this. For example, the screw compressor (1) may include a switching valve different from the second slide valve (80), and the switching valve may switch between the single-stage operation and the two-stage operation. In this case, for example, a refrigerant passage connecting the outlet side of the first compression chamber (21) and the outlet side of the second compression chamber (22) is provided, and the switching valve is provided in the refrigerant passage to open and close the refrigerant passage. When the switching valve is opened, the operation is switched to single-stage operation, and when the switching valve is closed, the operation is switched to two-stage operation. In this case, the switching valve is used to switch between single-stage operation and two-stage operation, and the second slide valve (80) is used to adjust the intermediate pressure, which is the pressure of the fluid in the intermediate pressure space (S), during two-stage operation.

[0086] Although the embodiments and modifications have been described above, it will be understood that various modifications in form and details are possible without departing from the spirit and scope of the claims. Furthermore, the above embodiments, modifications, and other embodiments may be combined or substituted as appropriate as long as the functionality of the subject matter of the present disclosure is not impaired.

[0087] The terms "first," "second," "third," etc. mentioned above are used to distinguish the terms to which these terms are attached, and do not limit the number or order of the terms. [Industrial Applicability]

[0088] As described above, the present disclosure is useful for screw compressors and refrigeration devices. [Explanation of symbols]

[0089] 1. Screw compressor 10 Casing 15 Cylindrical Wall 21 First compression chamber 22 Second compression chamber 40 screw rotor 50 First Gate Rotor 51 Gate 1 60 Second Gate Rotor 61 Gate 2 80 Second slide valve (valve) J Axial direction (valve movement direction)

Claims

1. a screw rotor (40); a plurality of gate rotors (50, 60) each having a gate (51, 61) that meshes with the screw rotor (40); a casing (10) having a cylindrical wall (15) into which the screw rotor (40) is rotatably inserted and through which the gates (51, 61) penetrate; an adjusting mechanism for adjusting the pressure of the fluid in the casing (10); Equipped with The screw rotor (40), the gates (51, 61), and the like are disposed inside the cylindrical wall (15). Multiple compression chambers are formed by The plurality of compression chambers include a first compression chamber (21) that compresses a fluid at a suction pressure introduced into the casing (10) to a pressure higher than the suction pressure, and a second compression chamber (22) to which the fluid compressed in the first compression chamber (21) is sent via an intermediate pressure space (S), the adjustment mechanism is capable of switching between a single-stage operation in which a fluid is compressed in the first compression chamber (21) of the first compression chamber (21) and the second compression chamber (22), and a two-stage operation in which a fluid is compressed in the first compression chamber (21) and the second compression chamber (22), and adjusting an intermediate pressure, which is the pressure of the fluid in the intermediate pressure space (S), during the two-stage operation; In the two-stage operation, the fluid compressed in the first compression chamber (21) is compressed in the second compression chamber (22), the adjustment mechanism includes a valve (80) movable in an opposing region (V) that indicates a rotor space surrounded by the gate rotors (50, 60) and the screw rotor (40); The valve (80) The screw compressor changes the timing at which the second compression chamber (22) is fully closed by changing the position within the opposing region (V).

2. 2. The screw compressor according to claim 1, wherein the valve (80) changes the timing at which the second compression chamber (22) is fully closed, thereby changing the volume of the second compression chamber (22) at the start of a process of compressing the fluid in the second compression chamber (22).

3. 3. The screw compressor according to claim 1, wherein the valve (80) switches between the single-stage operation and the two-stage operation.

4. 4. The screw compressor according to claim 3, wherein the valve is movable to a spaced position at which it is spaced from the rotor space, and when the valve is located at the spaced position, the valve maintains a state in which the intermediate pressure space is communicated with the outside of the machine.

5. A first passageway (91) and a second passageway (92) communicating with the intermediate pressure space (S) are provided inside the casing (10), The valve (80) When the compressor is located in the opposing region (V), the compressor sends fluid from the intermediate pressure space (S) to the second compression chamber (22) through the first passage (91), and sends fluid that has not entered the second compression chamber (22) due to the second compression chamber (22) being in a completely closed state to the intermediate pressure space (S) through the second passage (92); 5. The screw compressor according to claim 4, wherein, when the screw compressor is located at the separated position (W), the fluid in the intermediate pressure space (S) is sent to the outside of the aircraft through the first passage (91), and the fluid in the intermediate pressure space (S) is sent to the outside of the aircraft through the second passage (92).

6. The two-stage operation is performed when the valve (80) is located in the opposing region (V), The valve (80) adjusts the intermediate pressure by changing its position in the opposing region (V), 5. The screw compressor of claim 4, wherein the single-stage operation is performed when the valve (80) is in the separated position (W).

7. 3. The screw compressor according to claim 1, wherein the position of the valve (80) is continuously changeable, thereby continuously adjusting the timing at which the second compression chamber (22) is fully closed.

8. the first passage (91) and the second passage (92) are located on one side (J1) of the moving direction (J) of the valve (80) with respect to the separated position (W); 6. The screw compressor according to claim 5, wherein one side (J1) of the movement direction (J) indicates a direction from the separated position (W) toward the opposing region (V) in the movement direction (J) of the valve (80).

9. the valve (80) includes an end face (82) located on one side (J1) in a moving direction (J) of the valve (80), and the second passage (92) is disposed opposite to the end face (82); 6. The screw compressor according to claim 5, wherein one side (J1) of the movement direction (J) indicates a direction from the separated position (W) toward the opposing region (V) in the movement direction (J) of the valve (80).

10. the first passage (91) includes a first opening (91a) leading to the second compression chamber (22), the second passage (92) includes a second opening (92a) leading to the second compression chamber (22), 6. The screw compressor according to claim 5, wherein the second opening (92a) is located at a lower position than the first opening (91a).

11. 6. The screw compressor of claim 5, wherein the second passage (92) extends along the axis (N) of the valve (80).

12. A refrigeration system comprising the screw compressor according to claim 1 or 2.

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