Screw compressor

Abstract

This effectively suppresses contact between the slide valve and the screw rotor. [Solution] The device comprises a pair of screw rotors including a first rotor and a second rotor that mesh with each other, a casing having a bore that houses the first rotor and the second rotor, and a slide valve whose position in the axial direction is variable to adjust the capacity, wherein, in a cross section perpendicular to the axial direction, the ratio r1 / D3 of the distance between the perpendicular bisector of the line segment AB connecting the cusp point A, which is the intersection point of a first circle containing an arc corresponding to the outer diameter of the first rotor in the bore's contour, and a second circle containing an arc corresponding to the outer diameter of the second rotor in the bore's contour, and the intersection point B between the third circle containing an arc forming the contour of the slide valve and the first circle, and the center O3 of the third circle, and the diameter D3 of the third circle, is 0.1 or less.

Description

Technical Field

[0001] The present disclosure relates to a screw compressor.

Background Art

[0002] As a capacity control method in a screw compressor, slide valve type capacity control may be adopted. In slide valve type capacity control, a slide valve that forms a rotor accommodation chamber together with a casing is moved in the axial direction, and thereby, the gas sucked into the tooth groove space is bypassed to the suction side through an opening formed between the slide valve and the casing to adjust the air volume.

[0003] In a slide valve type screw compressor, a guide block or a guide surface that restricts the circumferential or radial movement of the slide valve is provided, thereby preventing the rotation of the slide valve during the movement of the slide valve and the contact between the screw rotor and the slide valve due to the rotation of the slide valve.

[0004] Patent Document 1 describes a screw compressor including a slide valve having a guide groove extending along the axial direction of the screw rotor on a surface opposite to a pair of screw rotors, and a guide metal (guide block) fixed to the casing side and slidably engaged with the guide groove. By sliding the guide metal with respect to the guide groove, the axial movement of the slide valve is guided.

[0005] Patent Document 2 describes a screw compressor including a pair of screw rotors, a slide valve movable in the axial direction, and a side cover provided with a discharge port, and a guide surface for restricting the radial movement of the slide valve is provided on the side cover.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

[0007] Incidentally, during the operation of a screw compressor, torque can be generated that rotates the cylindrical part of the slide valve. If the torque acting on the slide valve increases depending on the operating conditions of the screw compressor, friction with the slide valve can cause wear on the parts that restrict the rotation of the slide valve (the guide block and guide surface mentioned above), potentially leading to contact between the slide valve and the screw rotor. Such contact can cause vibration, noise, or a decrease in compressor performance.

[0008] In view of the above circumstances, at least one embodiment of the present invention aims to provide a screw compressor capable of effectively suppressing contact between a slide valve and a screw rotor. [Means for solving the problem]

[0009] A screw compressor according to at least one embodiment of the present invention is A pair of screw rotors including a first rotor and a second rotor that mesh with each other, A casing having a bore in which the first rotor and the second rotor are housed, A slide valve is provided within the casing, has a partially cylindrical shape, and its axial position is variable to adjust the volume. Equipped with, In the cross-section perpendicular to the axial direction, the ratio r1 / D3 of the diameter D3 of the third circle to the perpendicular bisector of the line segment AB connecting the cusp point A, which is the intersection point of the first circle containing the arc corresponding to the outer diameter of the first rotor in the bore's contour, and the second circle containing the arc corresponding to the outer diameter of the second rotor in the bore's contour, and the intersection point B between the third circle containing the arc forming the contour of the slide valve and the first circle, and the ratio r2 / D3 of the diameter D3 of the third circle to the center O3 of the third circle, are 0.1 or less. [Effects of the Invention]

[0010] According to at least one embodiment of the present invention, a screw compressor is provided that can effectively suppress contact between the slide valve and the screw rotor. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of a gas compression system including a screw compressor according to one embodiment. [Figure 2] This figure shows a cross-section AA of the screw compressor shown in Figure 1. [Figure 3] This is a schematic cross-sectional view of a slide valve according to one embodiment. [Figure 4] Figure 3 is a schematic diagram of the slide valve in a plan view. [Figure 5] This is a schematic diagram showing the positional relationship between the bore and slide valve of a screw compressor according to one embodiment. [Figure 6] This is a schematic diagram showing the positional relationship between the bore and slide valve of a screw compressor according to one embodiment. [Modes for carrying out the invention]

[0012] Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples.

[0013] FIG. 1 is a schematic view of gas compression equipment including a screw compressor according to some embodiments. As shown in the figure, the gas compression equipment 1 includes a screw compressor 2, an oil separator 4, a cooler 6, and a pump 8.

[0014] The screw compressor 2 is configured to compress and discharge the inhaled gas. The symbol Ps shown in the figure indicates the suction pressure of the screw compressor 2, and the symbol Pd indicates the discharge pressure of the screw compressor 2. Oil is supplied to the screw compressor 2 through an oil supply line (not shown) for cooling, lubrication, etc. The oil supplied to the screw compressor 2 is discharged together with the compressed gas.

[0015] The oil separator 4 is configured to separate oil from the mixture of compressed gas and oil discharged from the screw compressor 2. The oil separated by the oil separator 4 may be cooled by the cooler 6, pressurized by the pump 8, and then supplied again to the screw compressor 2 through the above-mentioned oil supply line (not shown) with or without bypassing the pump 8.

[0016] FIG. 1 is a schematic cross-sectional view along the axial direction of a screw compressor according to an embodiment. FIG. 2 is a view showing the A-A cross-section of the screw compressor shown in FIG. 1. As shown in FIGS. 1 and 2, the screw compressor 2 includes a pair of screw rotors (male rotor 15 and female rotor 17) to which a pair of rotor shafts 14 and 16 are respectively connected, and a casing 12 that houses the pair of screw rotors. The pair of screw rotors are housed in a bore 13 provided in the casing 12. In a cross-section perpendicular to the axial direction (see FIG. 2), the contour of the bore 13 includes a first portion 13a corresponding to the outer diameter of the male rotor 15 and a second portion 13b corresponding to the outer diameter of the female rotor 17.

[0017] The pair of rotor shafts 14 and 16 are each rotatably supported by radial bearings and thrust bearings (not shown). Oil is supplied to each bearing via an oil supply line (not shown).

[0018] The male rotor 15 and the female rotor 17 have helical teeth that mesh with each other. The meshing of the teeth of the male rotor 15 and the female rotor 17 and the casing 12 form a plurality of tooth groove spaces along the axial direction of the rotor shafts 14 and 16.

[0019] The rotor shaft 14 constituting the male rotor 15 is connected to the output shaft of a motor (not shown) and is configured to be rotationally driven by the motor. The female rotor 17 meshing with the male rotor 15 is rotationally driven by the rotation of the male rotor 15. The female rotor 17 rotates in a direction opposite to the rotation direction of the male rotor 15. When the male rotor 15 and the female rotor 17 rotate while meshed, the tooth groove spaces move from the suction side toward the discharge side in the axial direction.

[0020] Gas is inhaled into the above-mentioned tooth groove spaces from the suction space 18 formed in the casing 12 through the suction port 20. When the male rotor 15 and the female rotor 17 rotate, as these screw rotors rotate, the tooth groove spaces move from the suction side toward the discharge side in the axial direction. In this process, since the volume of the tooth groove space shrinks after the suction port 20 is closed, the gas in the tooth groove space is compressed. When the tooth groove space reaches the discharge port 22 and the tooth groove space communicates with the discharge space 24 formed in the casing 12, the compressed gas in the tooth groove space is discharged into the discharge space through the discharge port 22. The discharge port 22 includes a radial discharge port for discharging the compressed gas from the tooth groove space in the radial direction and an axial discharge port for discharging the compressed gas from the tooth groove space in the axial direction.

[0021] As shown in Figures 1 and 2, the screw compressor 2 is equipped with a slide valve 30 for adjusting the capacity according to the load on the screw compressor 2. The slide valve 30, together with the casing 12, forms a rotor housing chamber. By moving the slide valve 30 axially to the intake or discharge side, the size of the opening formed between the slide valve 30 and the casing 12 changes, and the airflow of the screw compressor 2 increases or decreases. The casing 12 may be provided with a guide portion 32 for guiding the axial movement of the slide valve 30.

[0022] As shown in Figure 1, the slide valve 30 may be driven by a hydraulic piston 34 to change its position in the axial direction. As shown in Figure 1, the hydraulic piston 34 may be supplied with oil from the pump 8. A solenoid valve 10 may be provided between the pump 8 and the hydraulic piston 34, and the hydraulic piston 34 and the slide valve 30 may be moved to the suction side or the discharge side by switching the hydraulic circuit with the solenoid valve 10.

[0023] Figure 3 is a schematic cross-sectional view of a slide valve 30 according to one embodiment, and Figure 4 is a schematic plan view of the slide valve 30 shown in Figure 3. Figure 3 is a diagram showing the BB cross-section of the slide valve 30 shown in Figure 4.

[0024] As shown in Figures 3 and 4, the slide valve 30 is provided so as to extend along the axial direction of a pair of screw rotors and includes a projection 40 located facing the pair of screw rotors and a cylindrical portion 38 located on the opposite side of the pair of screw rotors.

[0025] The cylindrical portion 38 is a part within a certain angular range around the central axis Q3 of the slide valve 30 and has an outer surface 38a that is slidable with the guide portion 32 (see Figure 1). The protruding portion 40 is a part within the remaining angular range around the central axis Q3 of the slide valve 30 and is connected to the cylindrical portion 38, and has a shape that protrudes toward the intermediate position Pc between the central axes Q1 and Q2 (see Figure 2) of the pair of screw rotors. The protruding portion 40 also has outer surfaces 40a and 40b that face the pair of screw rotors. The outer surface 40a has a shape corresponding to the outer diameter of the male rotor 15, and the outer surface 40b has a shape corresponding to the outer diameter of the female rotor 17.

[0026] As shown in Figure 4, the projection 40 of the slide valve 30 has a notch 31 provided at the discharge end in the axial direction. The notch 31 forms part of the discharge port 22 of the screw compressor 2 (radial discharge port).

[0027] The outer surfaces 40a and 40b of the protrusion 40 are pressure-receiving surfaces that receive pressure from the tooth groove space and the discharge space 24, respectively. Depending on the pressure received by the outer surfaces 40a and 40b, a moment is generated in the slide valve 30 around the central axis Q3. Since the moment generated by the pressure received by the outer surface 40a and the moment generated by the pressure received by the outer surface 40b rotate in opposite directions with respect to the central axis Q3, the rotational torque due to these moments cancels out when the product of the pressure received by the outer surfaces 40a and 40b and the size of the pressure-receiving surfaces is balanced.

[0028] In the axial direction, the relative position of the slide valve 30 and the discharge end face of the screw rotor may change depending on the operating conditions. However, when the position of the discharge end face of the screw rotor is at the position of the straight line Ld shown in Figure 4 (i.e., when the tip of the slide valve 30 is exposed from the discharge end face of the screw rotor), the shaded triangular portion of the outer surfaces 40a and 40b will be subjected to the pressure of the discharge space 24 of the screw compressor 2.

[0029] Figures 5 and 6 are schematic diagrams showing the positional relationship between the bore 13 and the slide valve 30 in a cross-section perpendicular to the axial direction of a screw compressor 2 according to one embodiment. Figures 5 and 6 include a pair of screw rotors, a first rotor and a second rotor, of the screw compressor 2. The diameters of the first rotor and the second rotor may be equal or different. Figures 5 and 6 show the first rotor and a second rotor with a smaller diameter than the first rotor. In Figures 5 and 6, as an example, the first rotor is a male rotor 15 and the second rotor is a female rotor 17, but in another example, the first rotor may be a female rotor 17 and the second rotor may be a male rotor 15.

[0030] In Figures 5 and 6, the first circle C1 is a circle containing the arc corresponding to the outer diameter of the first rotor in the contour of the bore 13 (corresponding to the first portion 13a of the contour of the bore 13), and the second circle C2 is a circle containing the arc corresponding to the outer diameter of the second rotor in the contour of the bore 13 (corresponding to the second portion 13b of the contour of the bore 13). The third circle C3 is a circle containing the arc forming the contour of the slide valve 30 (corresponding to the outer surface 38a of the cylindrical portion 38). The center O3 of the third circle C3 is the center of the cylinder of the slide valve 30. Here, the direction connecting the center O1 of the first circle C1 and the center O2 of the second circle C2 is defined as the first direction.

[0031] In some embodiments, as shown in Figures 5 and 6, for example, in a cross section perpendicular to the axial direction, the ratio r1 / D3 between the distance r1 (also called moment arm r1) between the perpendicular bisector LB1 of the line segment AB connecting the cusp point A, which is the intersection point of the first circle C1 and the second circle C2, and the intersection point B, which is the intersection point of the third circle C3 and the first circle C1, and the center O3 of the third circle C3, and the ratio r2 / D3 between the distance r2 (also called moment arm r2) between the distance LB2 (also called moment arm r2) between the perpendicular bisector LB2 of the line segment AC connecting the cusp point A, which is the intersection point C of the third circle C3 and the second circle C2, and the center O3 of the third circle, and the diameter D3 of the third circle C3, are both 0.1 or less.

[0032] In the example shown in Figure 5, the perpendicular bisector LB1 of line segment AB and the perpendicular bisector LB2 of line segment AC both pass through the center O3 of the third circle C3. Therefore, the distance r1 between the perpendicular bisector LB1 and the center O3 of the third circle C3, and the distance r2 between the perpendicular bisector LB2 and the center O3 of the third circle, are both zero.

[0033] In the above embodiment, the ratio r1 / D3 of the moment arm r1 of the rotational torque due to the pressure received on the first rotor side surface of the slide valve 30 (outer surface 40a of the protrusion 40) to the diameter D3 of the slide valve 30, and the ratio r2 / D3 of the moment arm r2 of the rotational torque due to the pressure received on the second rotor side surface (outer surface 40b of the protrusion 40) to the diameter D3 of the slide valve, are both 0.1 or less and are small, so the net rotational torque acting on the slide valve can be reduced. This makes it possible to suppress wear between the part that restricts the rotation of the slide valve 30 (guide block (not shown) and guide surface (not shown)) and the slide valve 30. As a result, contact between the slide valve 30 and the screw rotor (first rotor and second rotor) can be effectively suppressed.

[0034] In some embodiments, the above-mentioned ratios r1 / D3 and r2 / D3 may each be 0.05 or less. Alternatively, the above-mentioned ratios r1 / D3 and r2 / D3 may each be 0.02 or less.

[0035] In the above-described embodiment, the ratios r1 / D3 and r2 / D3 are 0.05 or less and 0.02 or less, respectively, and are even smaller, so the net rotational torque acting on the slide valve 30 can be further reduced. This makes it possible to more effectively suppress wear between the part that restricts the rotation of the slide valve 30 (guide block and guide surface) and the slide valve. As a result, it is possible to more effectively suppress contact between the slide valve 30 and the screw rotor (first rotor and second rotor).

[0036] In some embodiments, as shown in Figures 5 and 6, for example, the diameter of the second rotor is smaller than the diameter of the first rotor, and in a cross-section perpendicular to the axial direction, the center O3 of the third circle C3 is located closer to the center O2 of the second circle C2 than the cusp point A, which is the intersection point of the first circle C1 and the second circle C2, in the first direction described above.

[0037] The projected area of ​​the pressure-receiving tooth groove space on the outer surfaces 40a and 40b of the slide valve 30 is a parallelogram as shown in Figure 4 for both the first rotor (e.g., male rotor 15) side (Sm1 to Sm3) and the second rotor (e.g., female rotor 17) side (Sf1 to Sf3). Therefore, when the heights of the parallelograms are equal, the projected areas Sm1 to Sm3 on the first rotor side and Sf1 to Sf3 on the second rotor side are equal, and when the distances L1 and L2 shown in Figure 5 are approximately equal, the above-mentioned projected areas Sm1 to Sm3 and Sf1 to Sf3 are balanced to be equal. Here, distance L1 in Figure 5 is the distance between cusp point A and intersection point B between the cylinder of the slide valve 30 and the arc of the bore 13 corresponding to the first rotor (large diameter rotor) (distance between A and B), and distance L2 in Figure 5 is the distance between cusp point A and intersection point C between the cylinder of the slide valve 30 and the arc of the bore 13 corresponding to the second rotor (small diameter rotor) (distance between A and C).

[0038] Furthermore, if there is a difference between the discharge pressure and the pressure immediately before discharge, such as in cases of overcompression or undercompression, when the discharge-side end face of the screw rotor is at the position of the straight line Ld (Figure 4) on the slide valve 30, the tip of the slide valve 30 (the part exposed from the discharge-side end face of the screw rotor) becomes the discharge pressure, and a pressure difference is created on either side of the line segment Ld. At this time, if there is a difference in the area of ​​the triangular portion (shaded area in Figure 4) formed by the straight line Ld and the tip of the slide valve 30 between the first rotor side and the second rotor side, a torque is generated that rotates the slide valve 30.

[0039] In this respect, in the above-described embodiment, since the center of the cylinder of the slide valve 30 (i.e., the center O3 of the third circle C3) is located on the second rotor (small diameter rotor) side, the distance between the cusp point A and the intersection point B of the cylinder of the slide valve 30 and the arc of the bore 13 corresponding to the first rotor (large diameter rotor; for example, male rotor 15) (distance between A and B (L1 in Figure 5)) and the distance between the cusp point A and the intersection point C of the cylinder of the slide valve 30 and the arc of the bore 13 corresponding to the second rotor (small diameter rotor; for example, female rotor 17) (distance between A and C (L2 in Figure 5)) tend to be about the same. For this reason, the pressure-receiving area (the area that receives the pressure in each tooth groove space and the discharge pressure) on the first rotor side and the second rotor side of the slide valve 30 tend to be the same. In particular, even when the tip of the slide valve 30 is exposed from the discharge port 22, the pressure-receiving areas of the exposed portion (the triangular portion shown in Figure 4) and the non-exposed portion on the first rotor side and the second rotor side of the slide valve 30 tend to be equal. Therefore, the rotational torque due to the pressure received on the first rotor side surface (outer surface 40a of the protrusion 40) of the slide valve 30 and the rotational torque due to the pressure received on the second rotor side surface (outer surface 40b of the protrusion 40) can be easily canceled out. As a result, even when there is a difference between the discharge pressure and the pressure immediately before discharge, such as in the case of overcompression, the net rotational torque acting on the slide valve 30 can be reduced. This makes it possible to suppress wear between the part that restricts the rotation of the slide valve 30 (guide block (not shown) and guide surface (not shown)) and the slide valve 30. As a result, contact between the slide valve 30 and the screw rotor (first rotor and second rotor) can be effectively suppressed.

[0040] In some embodiments, within the cross-section described above, the ratio L2 / L1 of the distance L2 between the intersection point C of the third circle C3 and the second circle C2 and the cusp point A to the distance L1 between the intersection point B of the third circle C3 and the first circle C1 and the cusp point A may be 0.9 or more and 1.05 or less. Alternatively, the ratio L2 / L1 may be 0.95 or more and 1.03 or less.

[0041] In the above embodiment, the ratio L2 / L1 of the distance L2 (distance C above) between the intersection point C of the third circle and the second circle and the cusp point A (see Figure 5) to the distance L1 (distance A-B above; see Figure 5) between the intersection point B of the third circle and the first circle and the cusp point A is 0.9 to 1.05, or 0.95 to 1.03. That is, since the ratio L2 / L1 is close to 1, the distances L1 and L2 are approximately the same. Therefore, as described above, the pressure-receiving areas of the exposed and non-exposed parts on the first rotor side and the second rotor side of the slide valve 30 tend to be equal, and the torque for rotating the slide valve 30 tends to be small. As a result, wear between the part that restricts the rotation of the slide valve 30 (guide block and guide surface) and the slide valve 30 can be suppressed. As a result, contact between the slide valve 30 and the screw rotor (first rotor and second rotor) can be suppressed more effectively.

[0042] The contents described in each of the above embodiments can be understood, for example, as follows:

[0043] [1] A screw compressor (2) according to at least one embodiment of the present invention is A pair of screw rotors including a first rotor (e.g., male rotor 15) and a second rotor (e.g., female rotor 17) that mesh with each other, A casing (12) having a bore (13) in which the first rotor and the second rotor are housed, A slide valve (30) is provided within the casing, has a partially cylindrical shape, and its axial position is variable to adjust the volume. Equipped with, In the cross-section perpendicular to the axial direction, the ratio r1 / D3 of the distance r1 between the perpendicular bisector (LB1) of the line segment AB connecting the cusp point A, which is the intersection point of the bore contour containing the arc corresponding to the outer diameter of the first rotor and the second circle (C2), which is the intersection point of the bore contour containing the arc corresponding to the outer diameter of the second rotor and the third circle (C3), which contains the arc forming the contour of the slide valve, and the center O3 of the third circle, and the diameter D3 of the third circle, is 0.1 or less.

[0044] According to the configuration described in [1] above, the ratio r1 / D3 of the moment arm r1 of the rotational torque due to the pressure received on the first rotor side of the slide valve to the diameter D3 of the slide valve, and the ratio r2 / D3 of the moment arm r2 of the rotational torque due to the pressure received on the second rotor side of the slide valve to the diameter D3 of the slide valve, are both 0.1 or less and are small, so the net rotational torque acting on the slide valve can be reduced. This prevents wear from occurring between the parts that restrict the rotation of the slide valve (guide block and guide surface) and the slide valve itself. As a result, contact between the slide valve and the screw rotor can be effectively suppressed.

[0045] [2] In some embodiments, in the configuration of [1] above, The ratios r1 / D3 and r2 / D3 are 0.05 or less.

[0046] According to the configuration described in [2] above, the ratios r1 / D3 and r2 / D3 described above are both 0.05 or less, which is even smaller, so the net rotational torque acting on the slide valve can be further reduced. This makes it possible to more effectively suppress wear between the part that restricts the rotation of the slide valve (guide block and guide surface) and the slide valve. As a result, contact between the slide valve and the screw rotor can be more effectively suppressed.

[0047] [3] In some embodiments, in the configuration of [1] or [2] above, The second rotor has a smaller diameter than the first rotor. In the cross-section perpendicular to the axial direction, in the first direction connecting the center O1 of the first circle and the center O2 of the second circle, the center O3 of the third circle is located on the side of the center O2 of the second circle that is closer to the center O2 of the second circle than the cusp point A, which is the intersection point of the first circle and the second circle.

[0048] According to the configuration described in [3] above, the center O3 of the slide valve cylinder is located on the second rotor (small diameter rotor) side, so the distance between the cusp point A and the intersection point B of the cylinder and bore contour of the slide valve with the arc corresponding to the first rotor (large diameter rotor) (distance between A and B) and the distance between the cusp point A and the intersection point C of the cylinder and bore contour of the slide valve with the arc corresponding to the second rotor (distance between A and C) tend to be about the same. For this reason, the pressure-receiving area (the area that receives the pressure in each tooth groove space and the discharge pressure) on the first rotor side and the second rotor side of the slide valve tend to be the same. In particular, even when the tip of the slide valve is exposed from the discharge port, the pressure-receiving areas of the exposed and non-exposed parts on the first rotor side and the second rotor side of the slide valve tend to be equal. Therefore, the rotational torque due to the pressure on the first rotor side of the slide valve and the rotational torque due to the pressure on the second rotor side can be easily canceled out. As a result, even when there is a difference between the discharge pressure and the pressure just before discharge, such as in the case of overcompression, the net rotational torque acting on the slide valve can be reduced. This prevents wear from occurring between the parts that restrict the rotation of the slide valve (guide block and guide surface) and the slide valve itself. As a result, contact between the slide valve and the screw rotor can be effectively suppressed.

[0049] [4] In some embodiments, in the configuration of [3] above, Within the aforementioned cross-section, the ratio L2 / L1 of the distance L2 between the intersection point C of the third circle and the second circle and the cusp point A to the distance L1 between the intersection point B of the third circle and the first circle and the cusp point A is 0.9 or more and 1.05 or less.

[0050] According to the configuration described in [4] above, the ratio L2 / L1 of the distance L2 (the distance A and C described above) between the intersection point C of the third circle and the second circle and the cusp point A to the distance L1 (the distance A and B described above) between the intersection point B of the third circle and the first circle and the cusp point A is between 0.9 and 1.05. That is, since the ratio L2 / L1 is close to 1, the distances L1 and L2 described above are approximately the same. Therefore, as described in [1] above, wear between the part that restricts the rotation of the slide valve (guide block and guide surface) and the slide valve can be suppressed. As a result, contact between the slide valve and the screw rotor can be suppressed more effectively.

[0051] [5] In some embodiments, in the configuration of [4] above, The ratio L2 / L1 is between 0.95 and 1.03.

[0052] According to the configuration described in [5] above, the ratio L2 / L1 is between 0.95 and 1.03. That is, since the ratio L2 / L1 is closer to 1, the distances L1 and L2 are approximately the same. Therefore, as described in [3] above, wear between the part that restricts the rotation of the slide valve (guide block and guide surface) and the slide valve can be suppressed. As a result, contact between the slide valve and the screw rotor can be suppressed more effectively.

[0053] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and also includes modified forms of the embodiments described above, as well as forms that combine these forms as appropriate.

[0054] In this specification, expressions describing relative or absolute arrangements such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" shall not only describe such arrangements strictly, but also describe states of relative displacement with tolerances or angles or distances that allow for the same function to be achieved. For example, expressions such as "identical," "equal," and "homogeneous" that describe things being in an equal state not only describe a state of being strictly equal, but also describe a state in which there is a tolerance or a difference that is sufficient to achieve the same function. Furthermore, in this specification, expressions describing shapes such as quadrilaterals and cylindrical shapes shall not only represent geometrically precise quadrilaterals and cylindrical shapes, but also shapes that include uneven surfaces, chamfered surfaces, etc., to the extent that the same effect can be achieved. Furthermore, in this specification, the expressions “equipment,” “includes,” or “possess” of a component are not exclusive expressions that exclude the existence of other components. [Explanation of Symbols]

[0055] 1. Gas compression equipment 2 Screw compressor 4 Oil separator 6 Cooler 8 pumps 10 Solenoid valve 12 Casing 13 Boa 13a Part 1 13b Part 2 14 Rotor shaft 15 Male rotor 16 rotor shaft 17 Female rotor 18 Inhalation space 20 inhalation ports 22 discharge ports 24 Discharge space 30 Slide valve 31 Notch 32 Guide section 34 Hydraulic piston 38 Cylindrical part 38a outer surface 40 Protrusion 40a outer surface 40b outer surface A cusp point B intersection C intersection C1 1st Circle C2 2nd Circle C3 3rd Circle L1 distance L2 distance LB1 Perpendicular bisector LB2 Perpendicular bisector O1 center O2 center O3 center PC intermediate position Q1 center axis Q2 Center axis Q3 Central axis r1 Moment Arm r2 Moment Arm

Claims

1. A pair of screw rotors including a first rotor and a second rotor that mesh with each other, A casing having a bore in which the first rotor and the second rotor are housed, A slide valve is provided within the casing, has a partially cylindrical shape, and its axial position is variable to adjust the volume. Equipped with, In the cross-section perpendicular to the axial direction, the ratio r1 / D3 of the diameter D3 of the third circle to the perpendicular bisector of the line segment AB connecting the cusp point A, which is the intersection point of the bore contour containing the arc corresponding to the outer diameter of the first rotor and the second circle, which is the intersection point of the bore contour containing the arc corresponding to the outer diameter of the second rotor and the third circle containing the arc forming the contour of the slide valve, and the center O3 of the third circle, and the ratio r2 / D3 of the diameter D3 of the third circle, respectively, is 0.1 or less. Screw compressor.

2. The ratios r1 / D3 and r2 / D3 are 0.05 or less. The screw compressor according to claim 1.

3. The second rotor has a smaller diameter than the first rotor. In a cross-section perpendicular to the axial direction, in a first direction connecting the center O1 of the first circle and the center O2 of the second circle, the center O3 of the third circle is located closer to the center O2 of the second circle than the cusp point A, which is the intersection point of the first and second circles. The screw compressor according to claim 1 or 2.

4. Within the aforementioned cross-section, the ratio L2 / L1 of the distance L2 between the intersection point C of the third circle and the second circle and the cusp point A to the distance L1 between the intersection point B of the third circle and the first circle and the cusp point A is 0.9 or more and 1.05 or less. The screw compressor according to claim 3.

5. The ratio L2 / L1 is between 0.95 and 1.

03. The screw compressor according to claim 4.

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