JP7778045B2 - Liquid-cooled screw compressor - Google Patents

Description

The present invention relates to a liquid-cooled screw compressor.

A liquid-cooled screw compressor is known, which includes a screw rotor and a casing that houses the screw rotor and forms a working space together with the screw rotor. Liquid is supplied into the working space to cool the gas within the working space. In addition to cooling, the liquid supplied into the working space is also used to seal internal gaps that occur between the screw rotor and the casing, and to lubricate sliding parts.

Patent Document 1 proposes a technology for atomizing liquid by causing liquid particles supplied to the working space to collide with each other, with the aim of improving compressor performance.

In the compressor described in Patent Document 1, a fuel supply nozzle insertion hole is provided in the casing, and a fuel supply nozzle having multiple fuel supply paths for impinging jets inside is inserted into the fuel supply nozzle insertion hole. The fuel supply paths consist of a main fuel supply path and small-diameter secondary fuel supply paths that branch off from the main fuel supply path and are arranged in a V-shape. Because the fuel supply nozzle can be removed and attached in the compressor described in Patent Document 1, maintenance is easier than when the fuel supply paths for impinging jets are machined directly into the casing.

JP 2018-35782 A

Patent Document 1 discloses a fuel fill nozzle formed with multiple fuel supply paths in order to supply more liquid into the working space and improve cooling efficiency (see Figure 9 of Patent Document 1). However, with this fuel fill nozzle, multiple fuel fill paths consisting of a main fuel fill path and auxiliary fuel fill paths arranged in a V-shape must be formed inside the fuel fill nozzle, which requires time-consuming processing and raises concerns about increased processing costs.

The objective of the present invention is to provide a liquid-cooled screw compressor that is easy to process and maintain, and that can improve the cooling performance of the gas within the working space.

A liquid-cooled screw compressor according to one aspect of the present invention is a liquid-cooled screw compressor that draws in gas to generate compressed gas, and includes a screw rotor, a casing that houses the screw rotor and forms a working space together with the screw rotor, and a cartridge that is a separate member from the casing, wherein the casing and the outer surface of the cartridge form a liquid supply path for supplying liquid to the working space. The casing has a storage chamber that houses the screw rotor, an introduction passage through which liquid is introduced from outside the casing, and a communication passage that communicates the storage chamber with the introduction passage. By placing the cartridge in the communication passage, at least one pair of injection passages are formed by the tip end of the cartridge and the inner surface of the communication passage, and liquids injected from the at least one pair of injection passages collide with each other in the working space.

The present invention provides a liquid-cooled screw compressor that is easy to process and maintain, and can improve the cooling performance of the gas within the working space.

FIG. 1 is a plan cross-sectional view of a liquid-cooled screw compressor according to a first embodiment. FIG. 2 is a cross-sectional view taken along line II-II in FIG. FIG. 3 is an enlarged cross-sectional view of part III in FIG. FIG. 4 is a perspective view of the cartridge according to the first embodiment. FIG. 5 is a diagram showing the results of a numerical analysis of the liquid ejected from the ejection flow path formed by the cartridge according to the first embodiment. FIG. 6 is a plan cross-sectional view of a liquid-cooled screw compressor according to a comparative example of this embodiment. FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. FIG. 8 is a perspective view of a cartridge according to the second embodiment. FIG. 9 is a diagram showing the results of a numerical analysis of the liquid ejected from the ejection flow path formed by the cartridge according to the second embodiment. FIG. 10 is a perspective view of a cartridge according to the third embodiment. FIG. 11 is a plan view of the cartridge of FIG. 10 as seen from the direction XI. FIG. 12 is a diagram showing the results of a numerical analysis of the liquid ejected from the ejection flow path formed by the cartridge according to the third embodiment. FIG. 13 is a perspective view of a cartridge according to the fourth embodiment.

Embodiments of the present invention will be described below with reference to the drawings.

First Embodiment
A liquid-cooled screw compressor (hereinafter also referred to as compressor) 100 according to a first embodiment of the present invention will be described with reference to Figures 1 to 5. Figure 1 is a plan cross-sectional view of the compressor 100. Figure 2 is a cross-sectional view taken along line II-II in Figure 1. As shown in Figures 1 and 2, the compressor 100 includes a drive rotor 2 and a driven rotor 3 as a pair of screw rotors that rotate in mesh with each other, and a casing 1 that rotatably houses the drive rotor 2 and the driven rotor 3 inside. The compressor 100 rotates the screw rotors 2 and 3 to suck in air (gas) and generate compressed air (compressed gas).

The drive rotor (male rotor) 2 has multiple spiral male teeth. The driven rotor (female rotor) 3 has multiple spiral female teeth. The casing 1 has a bore 8 as a storage chamber for housing the intermeshed drive rotor 2 and driven rotor 3, an intake port for drawing in air, and a discharge port for discharging compressed air. The pair of screw rotors 2, 3 and the inner wall surface of the bore 8 form multiple working spaces (working chambers) C for compressing air.

A prime mover such as an electric motor is connected to the drive rotor 2. When the drive rotor 2 begins to rotate due to the prime mover, the driven rotor 3, which is meshed with the drive rotor 2, also begins to rotate. This causes air to be drawn into the working space C from the suction port. As the screw rotors 2 and 3 rotate, the working space C moves from the suction port side to the discharge port side, and as it moves, its volume decreases. As the volume of the working space C decreases, the air moves toward the discharge port side while being compressed, and is then discharged from the discharge port to the outside of the compressor 100.

In the liquid-cooled screw compressor 100, a cooling liquid (e.g., oil or water) is injected into the working space C to prevent the air temperature from rising due to the heat generated during the production of compressed air. The cooling liquid injected into the working space C is used not only to cool the air within the working space C, but also to seal gaps between the screw rotors 2, 3 and the inner wall surface of the bore 8 and gaps in the meshing areas between the drive rotor 2 and driven rotor 3, and to lubricate the sliding parts of the screw rotors 2, 3.

As shown in Figure 2, the compressor 100 is formed with a liquid supply path 7 that supplies liquid to the working space C. Note that the liquid supply path 7 is provided on both the drive rotor 2 side and the driven rotor 3 side, but since the configuration is the same on both sides, the following explanation will focus on one side.

The casing 1 has an inlet passage 9 through which liquid is introduced from outside the casing 1, a communication passage 10 that connects the storage chamber 8 with the inlet passage 9, and an elongated hole 5 that connects the communication passage 10 with the storage chamber 8. As shown in Figures 1 and 2, the elongated hole 5 is an opening that extends along the rotational axis direction of the screw rotors 2 and 3 (hereinafter simply referred to as the axial direction). In other words, the elongated hole 5 is an opening surface located at the boundary between the communication passage 10 and the storage chamber 8, and is formed in a rectangular shape with the axial direction of the screw rotors 2 and 3 as its longitudinal direction and a direction perpendicular to the axial direction (horizontal direction) as its transverse direction. In this embodiment, the elongated hole 5 has a pair of opposing long sides and a pair of semicircular arcs connecting the pair of long sides at both ends. The elongated hole 5 is formed in both the male bore that houses the drive rotor 2 and the female bore that houses the driven rotor 3.

The communication passage 10 forms a flattened rectangular space, and by placing a flattened rectangular cartridge 6 in the communication passage 10, a pair of liquid supply paths 7 are formed by the inner wall surface of the casing 1 and the outer surface of the cartridge 6. The cartridge 6 is detachable from the casing 1.

The configuration of the liquid supply path 7 will be described in detail with reference to Figures 3 and 4. Figure 3 is an enlarged cross-sectional view of section III in Figure 2, and Figure 4 is a perspective view of the cartridge 6. As shown in Figures 3 and 4, the cartridge 6 is rectangular and flat, and has a pair of opposing wide surfaces 62 and a pair of opposing narrow surfaces 64. The wide surfaces 62 and the narrow surfaces 64 are planar and perpendicular to each other. The pair of wide surfaces 62 are parallel to each other, and the pair of narrow surfaces 64 are parallel to each other. When the cartridge 6 is placed in the communicating passage 10, the base end 69 (see Figure 4) is located on the introduction passage 9 side, and the tip end 61 is located on the bore 8 side. In other words, the cartridge 6 extends vertically within the communicating passage 10 from the introduction passage 9 side to the bore 8 side. The area of the wide surface 62 is larger than the area of the base end surface (lower end surface) and the narrow surface 64 of the cartridge 6, respectively. The base end surface of the cartridge 6 is a plane perpendicular to both the wide surface portion 62 and the narrow surface portion 64.

The cartridge 6 is formed with a through-hole 66 that penetrates from one wide surface portion 62 to the other wide surface portion 62. The cross-sectional shapes of the through-hole 66 and the introduction passage 9 (see Figure 2) extending horizontally are circular. The opening area of the through-hole 66 is preferably equal to or greater than the flow path cross-sectional area of the introduction passage 9. In other words, the diameter of the through-hole 66 is preferably the same as or larger than the diameter of the introduction passage 9. The cartridge 6 is positioned within the communication passage 10 so that the central axis of the through-hole 66 coincides with the central axis of the introduction passage 9. As a result, when viewed in the thickness direction of the cartridge 6, the entire inner circumferential surface of the introduction passage 9 is positioned within the through-hole 66.

The tip portion 61 of the cartridge 6 is tapered and has a pair of tapered surface portions 63. In other words, the thickness (the distance between the pair of tapered surface portions 63) of the tip portion 61 decreases toward the tip (the apex 6t). A groove (recess) 65 is formed in the tapered surface portion 63, extending from the upper end of the wide surface portion 62 toward the apex 6t of the cartridge 6. The apex 6t is a flat surface parallel to the base end surface of the cartridge 6. The groove 65 is formed between the axial end portions 63a at both axial ends of the tapered surface portion 63. The bottom surface 65a (hereinafter also referred to as the tapered surface) of the groove 65 is flat and inclined relative to the wide surface portion 62 so that the distance between the pair of tapered surfaces 65a decreases as the distance from the wide surface portion 62 approaches the apex 6t. The pair of tapered surfaces 65a are connected by the apex 6t of the cartridge 6.

As shown in FIG. 3, the communication passage 10 is formed with a pair of inclined surface portions 10a facing the pair of tapered surface portions 63 of the cartridge 6, a pair of first flow path walls 10b facing the pair of wide surface portions 62, and a pair of second flow path walls (not shown) facing the pair of narrow surface portions 64. In this embodiment, a step portion 10c is formed between the tapered surface portions 63 and the first flow path walls 10b, but the step portion 10c may be omitted. In other words, the tapered surface portions 63 and the first flow path walls 10b may be directly connected.

The communicating passage 10 is formed, for example, by protruding a tapered V-shaped end mill into the bore (storage chamber) 8 and then moving the end mill in the axial direction of the screw rotors 2 and 3. The length of the long hole 5 in the short direction can be adjusted by adjusting the amount the end mill protrudes. Furthermore, the length of the long hole 5 in the long direction can be adjusted by adjusting the amount the end mill moves in the axial direction of the screw rotors 2 and 3. In other words, the opening area of the long hole 5 is determined by the amount the end mill protrudes and moves.

When machining is performed using an end mill or similar device with a tapered V-shaped tip, a V-groove with a pair of inclined surfaces 10a is formed on the upstream side of the elongated hole 5. The tip 61 of the cartridge 6 is positioned along this V-groove, forming a pair of injection flow paths 13 between the V-groove of the casing 1 and the tip 61 of the cartridge 6.

As shown in FIG. 3, the cartridge 6 and the communicating passage 10 are formed symmetrically in the left-right direction in the figure. By placing the cartridge 6 at the center of the communicating passage 10 in the left-right direction in the figure, the cartridge 6 divides the space within the communicating passage 10 equally in the left-right direction in the figure. In other words, the pair of liquid supply paths 7 are formed symmetrically on either side of the cartridge 6. The cartridge 6 is placed so that its top (tip) 6t is flush with the inner surface of the bore (storage chamber) 8. Note that to reliably prevent the tip 61 of the cartridge 6 from contacting the screw rotors 2, 3, the top 6t of the tip 61 of the cartridge 6 may be positioned below the bottom end surface of the bore 8.

The pair of liquid supply paths 7 have a pair of liquid supply storage spaces 12 that store the liquid supplied from the introduction path 9, and a pair of injection flow paths 13 that inject the liquid in the pair of liquid supply storage spaces 12 into the working space C.

When the cartridge 6 is placed in the communication passage 10, the pair of supply liquid storage spaces 12 are formed by the pair of wide surface portions 62 of the cartridge 6 and the pair of first flow path walls 10b and pair of second flow path walls (not shown) that form the inner surface of the communication passage 10.

When the cartridge 6 is placed in the communication passage 10, the pair of injection flow passages 13 are formed by the pair of tapered surface portions 63 of the cartridge 6 and the pair of inclined surface portions 10a that form the inner surface of the communication passage 10. More specifically, when the tapered surface of the axial end portion 63a of the cartridge 6 abuts against the inclined surface portions 10a, the grooves 65 of the tapered surface portions 63 and the inclined surface portions 10a form the injection flow passage 13 with a rectangular cross section.

The flow path cross-sectional area of the liquid supply storage space 12 is larger than the flow path cross-sectional area of the jet flow path 13 to which liquid is supplied from the liquid supply storage space 12. Liquid is introduced into the liquid supply storage space 12 from the horizontally arranged introduction path 9, and the liquid introduced into the liquid supply storage space 12 flows toward the jet flow path 13 (i.e., upward in the figure). Because the flow path cross-sectional area of the liquid supply storage space 12 is larger than the flow path cross-sectional area of the jet flow path 13, the speed of the liquid flowing through the liquid supply storage space 12 is slower than the speed of the liquid flowing through the jet flow path 13. In this way, by configuring the liquid to flow within a wide space until it reaches the jet flow path 13, pressure loss can be minimized. This allows the pressure of the liquid in the jet flow path 13 to be maintained at a high level, allowing the liquid to be ejected from the jet flow path 13 with great force.

Each of the pair of injection channels 13 has an injection opening 11 facing the working space C, formed by the apex 6t of the tip 61 of the cartridge 6 and the elongated hole 5 of the casing 1. The injection opening 11 is a rectangular outlet that ejects liquid from the injection channel 13 into the working space C, i.e., the open end face of the injection channel 13, and is exposed within the bore (storage chamber) 8.

The axial length (opening length) of the injection openings 11 of the screw rotors 2, 3 is longer than the length (opening width) perpendicular to the axial direction. The injection openings 11 have their opening width and length determined so that liquid is injected from the injection openings 11 in the form of a liquid film. In other words, the injection flow path 13 according to the first embodiment is a liquid film injection flow path that injects a liquid film. The liquid films injected from the injection openings 11 of a pair of injection flow paths 13 collide with each other within the working space C.

The pair of tapered surfaces 65a are formed so that the angle they form with each other is 30 degrees or more. Furthermore, the pair of inclined surface portions 10a are formed so that the angle they form with each other is 30 degrees or more. The tapered surfaces 65a and inclined surface portions 10a are arranged parallel to each other. Liquid is sprayed into the working space C along the tapered surfaces 65a and inclined surface portions 10a. In other words, the injection flow paths 13 are formed so that the angle (collision angle) θ between the injection directions of the liquid sprayed from each of the pair of injection flow paths 13 is 30 degrees or more.

As shown in Figure 2, the base end 69 of the cartridge 6 is located below the introduction passage 9, which extends horizontally. Although not shown, the communication passage 10 extends to the bottom end surface of the casing 1, and an insertion opening for inserting the cartridge 6 into the communication passage 10 is formed on the bottom end surface of the casing 1. A closing member (not shown) is attached to the insertion opening, and the insertion opening is closed by the closing member.

Figure 5 shows the results of a numerical analysis of the liquid (liquid film) sprayed from the spray flow path 13 formed by the cartridge 6. The black rectangular plane in the figure is a virtual plane that shows the pressure state of the liquid film and is not actually provided in the product.

The pair of injection flow paths 13 formed by the inclined surface portion 10a of the casing 1 and the groove 65 of the cartridge 6 have a thin gap shape. As a result, oil is injected from the pair of injection flow paths 13 in the form of a liquid film. The thin liquid film injected from one of the pair of injection flow paths 13 collides with the thin liquid film injected from the other of the pair of injection flow paths 13 within the working space C. Numerical analysis results confirmed that the collision of the injected liquids in the form of liquid films promotes thinning of the liquid and increases the surface area of the liquid. The colliding liquid films spread and atomize into a plane, thereby facilitating cooling of the compressed air within the working space C.

In this embodiment, the upstream side of the elongated hole 5 in the casing 1 is a space (communicating passage 10) capable of accommodating the cartridges 6 for forming the flow path, and a pair of liquid supply paths 7 are formed by placing the flat cartridges 6 in the communicating passage 10 in the casing 1. Liquid is ejected into the working space C via the liquid supply paths 7 formed by the outer surface of the cartridges 6 and the casing 1. In this embodiment, an ejection opening 11 is formed extending along the axial direction of the screw rotors 2, 3, and a thin liquid film is ejected from the ejection opening 11.

Now, with reference to Figures 6 and 7, a compressor 900 according to a comparative example of this embodiment will be described. As shown in Figures 6 and 7, in the compressor 900 according to the comparative example of this embodiment, an injection flow path 913 is formed by drilling holes in the casing 1. The injection flow path 913 is a small-diameter circular opening that penetrates from the introduction path into the bore 8. Liquid is injected in a cylindrical shape from this injection flow path 913. However, in such an injection flow path (drilled hole) 913, the liquid does not diffuse, making it difficult to promote cooling.

In contrast, in the compressor 100 according to this embodiment shown in Figures 1 to 5, the axial lengths of the screw rotors 2, 3 in the cartridge 6 and the elongated hole 5 are increased, thereby ensuring a sufficient supply of liquid while spraying a thin film of oil, and causing the liquid films to collide with each other, effectively dispersing the liquid. This effectively promotes cooling of the compressed air in the working space C.

In addition, in this embodiment, a groove 65 is formed on the outer surface of the cartridge 6, and the cartridge 6 is placed in a communication passage 10 formed in the casing 1, thereby forming an ejection flow passage 13 between the casing 1 and the outer surface of the cartridge 6, which is a separate member from the casing 1. Therefore, this method is easier to process than the technology described in Patent Document 1 (hereinafter also referred to as prior art), which forms multiple flow passages inside the cartridge 6 to increase the liquid flow rate.

The cartridge 6 is detachable from the casing 1. Therefore, maintenance such as cleaning of the injection flow path 13 can be easily performed by removing the cartridge 6 from the casing 1. Furthermore, if the operating conditions of the compressor 100 change, the cartridge 6 attached to the casing 1 can be changed to form a liquid supply path 7 that suits the changed operating conditions.

The above-described embodiment provides the following advantages:

(1) The compressor 100 is a liquid-cooled screw compressor that draws in air (gas) and generates compressed air (compressed gas). The compressor 100 includes screw rotors 2 and 3, a casing 1 that houses the screw rotors 2 and 3 and forms a working space C together with the screw rotors 2 and 3, and a cartridge 6 that is a separate member from the casing 1. The casing 1 and the outer surface of the cartridge 6 form a liquid supply path 7 that supplies liquid to the working space C.

In this configuration, the amount of liquid (refrigerant) supplied into the working space C can be adjusted by machining the external shape of the cartridge 6, preventing a shortage of liquid. Therefore, according to this embodiment, it is possible to provide a compressor 100 that has excellent workability and maintainability for the liquid supply path 7 and can easily improve the cooling performance for the air (gas) in the working space C. As described above, because the shape of the liquid supply path 7 can be determined by machining the external shape of the cartridge 6, processing costs can be reduced compared to when the liquid supply path 7 is formed inside the cartridge 6. As a result, the manufacturing costs of the compressor 100 can be reduced.

(2) The casing 1 has a bore (storage chamber) 8 that stores the screw rotors 2 and 3, an introduction passage 9 through which liquid is introduced from outside the casing 1, and a communication passage 10 that connects the bore 8 and the introduction passage 9. When the cartridge 6 is placed in the communication passage 10, a pair of injection flow passages 13 are formed by the tip 61 of the cartridge 6 and the inner surface of the communication passage 10. The liquids injected from the pair of injection flow passages 13 collide with each other within the working space C.

With this configuration, the liquids injected from a pair of injection channels 13 collide with each other, allowing the atomized liquid to be dispersed over a wide area within the working space C. This improves the cooling performance of the air within the working space C compared to when the injected liquids are not allowed to collide with each other (see Figures 6 and 7).

(3) When the cartridge 6 is placed in the communication passage 10, the injection flow path 13 according to this embodiment is formed by a pair of tapered surface portions 63 and a pair of inclined surface portions 10a, and is therefore a single pair. The tapered surface portion 63 has a groove 65 formed therein that allows the liquid (refrigerant) to be injected in the form of a liquid film. In other words, the injection flow path 13 according to this embodiment is a liquid film injection flow path that injects a liquid film. The liquid films injected from the pair of injection flow paths (liquid film injection flow paths) 13 collide with each other within the working space C.

With this configuration, the liquid films collide with each other, promoting thinning and dispersing the atomized liquid over a wide area. Thinning and atomization of the liquid increases the surface area of the liquid (i.e., the heat exchange area), allowing the compressed air in the working space C to be cooled more effectively, improving compressor performance.

(4) The pair of liquid supply paths 7 have a pair of liquid supply storage spaces 12 that store the liquid supplied from the introduction path 9, and a pair of injection flow paths 13 that inject the liquid in the liquid supply storage spaces 12 into the working space C. The pair of liquid supply storage spaces 12 are formed by a pair of wide surface portions 62 of the cartridge 6 and the inner surface of the communication path 10, and the pair of injection flow paths 13 are formed by a pair of tapered surface portions 63 of the cartridge 6 and a pair of inclined surface portions 10a of the communication path 10. The flow path cross-sectional area of the pair of liquid supply storage spaces 12 formed upstream of the pair of injection flow paths 13 is larger than the flow path cross-sectional area of the pair of injection flow paths 13.

In this configuration, a liquid supply storage space 12 with a larger flow path cross-sectional area than the injection flow path 13 is formed from the introduction path 9 to the injection flow path 13, thereby reducing pressure loss of the liquid flowing through the liquid supply path 7. This allows the liquid to be forcefully injected from the injection opening 11 under high pressure, spreading the liquid over a wider area.

(5) The pair of liquid supply paths 7 are formed symmetrically across the cartridge 6. This reduces the difference in pressure between the liquid in the upstream liquid supply path 7 of the pair of liquid supply paths 7 and the liquid in the downstream liquid supply path 7 of the pair of liquid supply paths 7. This makes it possible to spray liquid from each of the pair of ejection flow paths 13 at approximately the same speed, making it easier to control the location where the liquids collide. In this embodiment, liquid films are sprayed evenly from each of the pair of ejection flow paths 13, so the liquid films after collision extend straight upward.

(6) Furthermore, the cross-sectional shape of the inlet passage 9 is circular, and the cartridge 6 is formed with a circular through-hole 66 disposed in the inlet passage 9. The opening area of the through-hole 66 is equal to or greater than the cross-sectional area of the inlet passage 9. If the opening area of the through-hole 66 were smaller than the cross-sectional area of the inlet passage 9, the pressure loss of the liquid passing through the through-hole 66 would increase. As a result, the difference in pressure between the liquid in the upstream liquid supply path 7 and the liquid in the downstream liquid supply path 7 would increase. In this case, a difference in speed occurs between the liquid ejected from one of the pair of ejection paths 13 and the liquid ejected from the other of the pair of ejection paths 13, making it difficult to control the collision site between the liquids. In contrast, in this embodiment, the opening area of the through-hole 66 disposed in the inlet passage 9 is equal to or greater than the cross-sectional area of the inlet passage 9, thereby suppressing the pressure loss of the liquid passing through the through-hole 66. This reduces the pressure and velocity differences between the liquids ejected from each of the pair of ejection openings 11, making it easier to control the locations where the liquids collide.

(7) The injection flow paths 13 are formed so that the angle (collision angle) θ between the injection directions of the liquid injected from each of the paired injection flow paths 13 is 30 degrees or greater. In this embodiment, the angle between the extension lines of a pair of injection flow paths 13 is 30 degrees or greater. With this configuration, the liquid can be atomized more effectively and the surface area of the liquid can be increased compared to when the liquids are collided with each other at a collision angle θ of less than 30 degrees.

(8) The communication passage 10 and the bore 8 are connected by a long hole 5 that runs along the axial direction of the screw rotors 2, 3, and each of the pair of injection flow paths 13 has an injection opening 11 that faces the working space C formed by the tip 61 of the cartridge 6 and the long hole 5. With this configuration, the shape and opening area of the injection opening 11 can be adjusted by adjusting the shape of the long hole 5 and the shape of the tip 61 of the cartridge 6.

Second Embodiment
A cartridge 6B according to a second embodiment of the present invention will be described with reference to Figures 8 and 9. Components that are the same as or equivalent to those described in the first embodiment are given the same reference symbols, and differences will be mainly described. Figure 8 is a perspective view of the cartridge 6B according to the second embodiment. Figure 9 is a view similar to Figure 5, showing the results of a numerical analysis of liquid ejected from an ejection flow path 13B formed by the cartridge 6B according to the second embodiment.

The casing 1 according to the second embodiment is similar to that according to the first embodiment, but the cartridge 6B according to the second embodiment differs from the cartridge 6 described in the first embodiment. In the first embodiment, one groove 65 was formed in each of the pair of tapered surface portions 63 (see Figures 3 and 4). In contrast, in the second embodiment, as shown in Figure 8, multiple grooves 67B are formed in each of the pair of tapered surface portions 63B, extending linearly from the wide surface portion 62 to the apex (tip) 6Bt of the tip portion 61. The multiple grooves 67B are arranged along the axial direction of the screw rotors 2 and 3. The multiple grooves 67B are each formed along a direction perpendicular to the axial direction of the screw rotors 2 and 3.

In the first embodiment, an example was described in which a cartridge 6 is placed in the communication passage 10, and thus a pair of tapered surface portions 63 and a pair of inclined surface portions 10a form only one pair of ejection flow paths 13 for one cartridge 6 (see Figures 3 and 4). In contrast, in the second embodiment, a cartridge 6B is placed in the communication passage 10, and thus a plurality of pairs of ejection flow paths 13B (six pairs in the illustrated example) are formed for one cartridge 6B, and thus a plurality of grooves 67B on a pair of tapered surface portions 63B and a pair of inclined surface portions 10a form multiple pairs of ejection flow paths 13B for one cartridge 6B.

Furthermore, the injection flow paths 13 according to the first embodiment were liquid film injection flow paths that injected a liquid film. In contrast, the injection flow paths 13B according to the second embodiment are jet injection flow paths that eject a jet. In each of the pairs of injection flow paths 13B, an injection opening 11B facing the working space C is formed by the apex 6Bt of the tip portion 61 of the cartridge 6B and the elongated hole 5.

The jets ejected from the multiple pairs of jet ejection flow paths 13B collide with each other within the working space C.

Furthermore, as in the first embodiment, the sum of the flow path cross-sectional areas of a pair of supply liquid storage spaces 12 is greater than the sum of the flow path cross-sectional areas of multiple pairs of injection flow paths 13.

In the second embodiment, multiple pairs of injection flow paths (jet injection flow paths) 13B are formed by the casing 1 and the outer surface of the cartridge 6B. The jets injected from each pair of injection flow paths 13B collide with each other within the working space C. According to the second embodiment, as shown in FIG. 9, the collision of the jets causes the liquid to fan out in the axial direction of the screw rotors 2 and 3, thereby increasing the surface area of the liquid. Therefore, according to the second embodiment, as with the first embodiment, a compressor 100 can be provided that has excellent workability and maintainability of the liquid supply path 7 and can easily improve the cooling performance for the air (gas) within the working space C.

Third Embodiment
A cartridge 6C according to a third embodiment of the present invention will be described with reference to Figures 10 to 12. Components that are the same as or equivalent to those described in the second embodiment are designated by the same reference symbols, and differences will be mainly described. Figure 10 is a perspective view of the cartridge 6C according to the third embodiment. Figure 11 is a plan view of the cartridge 6C of Figure 10 as viewed from the XI direction. Figure 12 is a view similar to Figures 5 and 9, and shows the results of a numerical analysis of liquid ejected from an ejection flow path 13C formed by the cartridge 6C according to the third embodiment.

In the second embodiment, the multiple grooves 67B on the tapered surface portion 63B were formed along a direction perpendicular to the axial direction of the screw rotors 2, 3 (see Figure 8). In contrast, in the third embodiment, as shown in Figures 10 and 11, the multiple grooves 67C on the tapered surface portion 63C are formed along directions that are inclined with respect to both the axial direction of the screw rotors 2, 3 and the direction perpendicular to the axial direction.

As shown in FIG. 11, in the third embodiment, the extension direction D1 of the groove 67C in a plan view intersects with both the axial direction D0 of the screw rotors 2 and 3 and the direction perpendicular to the axial direction D0 (the plane perpendicular to the axial direction D0).

In the third embodiment, similar to the second embodiment, multiple pairs of injection flow paths (jet injection flow paths) 13C are formed by the casing 1 and the outer surface of the cartridge 6C, thereby achieving the same effects as the second embodiment. Furthermore, in the third embodiment, the injection flow paths 13C are formed obliquely with respect to the axial direction D0 and the direction perpendicular to the axial direction D0 in a plan view. Therefore, as shown in FIGS. 11 and 12, when the jets collide with each other, the liquid spreads in a fan shape in a direction perpendicular to the extension direction D1 of the grooves 67C, thereby increasing the surface area of the liquid. According to this third embodiment, by adjusting the angle φ of the multiple grooves 67 (the angle between the axial direction D0 and the extension direction D1 of the grooves 67C in a plan view), the liquid injected from the paired injection flow paths 13C and colliding with each other can be dispersed in a direction along the tooth grooves of the screw rotors 2 and 3 or toward the tooth groove cross section.

Fourth Embodiment
A cartridge 6D according to a fourth embodiment of the present invention will be described with reference to Fig. 13. Note that the same reference symbols are used for components that are the same as or equivalent to those described in the third embodiment, and differences will be mainly described. Fig. 13 is a perspective view of the cartridge 6D according to the fourth embodiment.

The fourth embodiment differs from the third embodiment in that a groove 68 extending in the axial direction of the screw rotors 2 and 3 is formed at the top (tip) of the tip portion 61 of the cartridge 6D. The groove 68 is formed to expand the liquid supply range within the working space C. In this embodiment, the groove 68 is formed with a V-shaped cross section that is recessed from the tip end of the tip portion 61 toward the base end.

In the third embodiment, as shown in FIG. 10, the injection opening 11C is configured to open on the top surface, and a pair of injection channels 13C is separated by a partition. In contrast, in the fourth embodiment, as shown in FIG. 13, the injection opening 11D is formed as a V-shaped groove 68, and a space is formed between each pair of injection openings 11D. In the third embodiment, depending on the diffusion conditions after the jet collision, the partition inside the groove 67C immediately before injection may impede diffusion. In contrast, in the cartridge 6D according to the fourth embodiment, the V-shaped groove 68 is formed at the tip of the tip portion 61, eliminating the partition inside the groove 67D immediately before injection, thereby suppressing the impediment to diffusion after the jets impinge. In other words, according to the fourth embodiment, the liquid can be diffused over a wider area than in the third embodiment.

As described above, in the compressors according to the first to fourth embodiments, the combination of the casing and the outer surface of the cartridge forms one or more pairs of injection flow paths that allow the injected liquids to collide with each other. Therefore, simply by changing the processing details and longitudinal length (axial direction of the screw rotors 2, 3) of one cartridge provided for one screw rotor, it is possible to improve the cooling performance within the working space C and easily change the flow rate of the liquid used to cool the compressed air.

<Other embodiments>
The present invention is not limited to the above-described embodiments, but includes various modifications. The above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. That is, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is also possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

In the above-described embodiment, a twin-rotor liquid-cooled screw compressor has been described as an example, but the present invention can also be applied to screw compressors other than twin-rotor types, such as single-rotor and triple-rotor types. Furthermore, the gas compressed by the compressor is not limited to air.

1... casing, 2... drive rotor (screw rotor), 3... driven rotor (screw rotor), 5... elongated hole, 6, 6B, 6C, 6D... cartridge, 6t, 6Bt, 6Dt... top (tip), 7... liquid supply path, 8... bore (storage chamber), 9... introduction path, 10... communication path, 10a... inclined surface portion, 10b... first flow path wall, 10c... step portion, 11, 11C, 11D... injection opening, 12... liquid supply storage space, 13... injection flow path (liquid film injection flow path) ), 13B... injection flow path (jet injection flow path), 13C... injection flow path (jet injection flow path), 61... tip portion, 62... wide surface portion, 63, 63B, 63C... tapered surface portion, 63a... axial end portion, 64... narrow surface portion, 65... groove (recess), 65a... bottom surface (tapered surface), 66... through hole, 67, 67B, 67C, 67D... groove, 68... groove, 69... base end portion, 100... compressor (liquid-cooled screw compressor), C... working space (working chamber), θ... collision angle

Claims (12)

A liquid-cooled screw compressor that sucks in gas and generates compressed gas,
A screw rotor;
a casing that houses the screw rotor and defines an operating space together with the screw rotor;
a cartridge that is a separate member from the casing,
a liquid supply path for supplying liquid to the working space is formed by the casing and an outer surface of the cartridge ;
the casing has a storage chamber that stores the screw rotor, an introduction passage through which a liquid is introduced from the outside of the casing, and a communication passage that communicates the storage chamber with the introduction passage,
When the cartridge is disposed in the communication passage, at least one pair of ejection flow passages is formed by the tip end of the cartridge and the inner surface of the communication passage,
The liquids ejected from the at least one pair of ejection channels collide with each other in the working space.
Liquid-cooled screw compressor. 2. The liquid-cooled screw compressor according to claim 1 ,
The cartridge has a pair of wide surfaces facing each other,
The tip of the cartridge is formed in a tapered shape having a pair of tapered surfaces,
the communication passage of the casing has a pair of inclined surface portions facing the pair of tapered surface portions of the cartridge,
a pair of the liquid supply paths are formed by the casing and an outer surface of the cartridge;
The pair of liquid supply paths include:
a pair of liquid supply storage spaces formed by the pair of wide surface portions of the cartridge and an inner surface of the communication passage, the liquid supply storage spaces storing the liquid supplied from the introduction passage;
one or more pairs of ejection flow paths formed by the pair of tapered surface portions of the cartridge and the pair of inclined surface portions of the communication path, for ejecting liquid from the supply liquid storage space into the working space,
a flow path cross-sectional area of the pair of feed liquid storage spaces being larger than a flow path cross-sectional area of the at least one pair of injection flow paths; 3. The liquid-cooled screw compressor according to claim 2 ,
When the cartridge is disposed in the communication passage, only one pair of ejection flow passages is formed by the pair of tapered surface portions and the pair of inclined surface portions,
the ejection flow path is a liquid film ejection flow path that ejects a liquid film,
the liquid films injected from the pair of liquid film injection channels collide with each other in the working space. 3. The liquid-cooled screw compressor according to claim 2 ,
When the cartridge is disposed in the communication passage, a plurality of pairs of the ejection flow passages are formed by the pair of tapered surface portions and the pair of inclined surface portions,
the jet flow path is a jet flow path that jets a jet,
the jets injected from the pairs of jet injection passages collide with each other in the working space. 5. The liquid-cooled screw compressor according to claim 4 ,
a plurality of grooves extending linearly from the wide surface portion to the tip of the tip portion are formed on each of the pair of tapered surface portions;
the plurality of grooves and the inclined surface portions form the plurality of pairs of jet injection flow paths. 2. The liquid-cooled screw compressor according to claim 1 ,
the communication passage and the storage chamber are connected by a long hole extending along the axial direction of the screw rotor,
a nozzle opening portion facing the working space is formed in each of the at least one pair of injection passages by the tip end portion of the cartridge and the elongated hole. 2. The liquid-cooled screw compressor according to claim 1 ,
The injection flow paths are formed so that the angle between the injection directions of the liquid injected from each of the paired injection flow paths is 30 degrees or more. 6. The liquid-cooled screw compressor according to claim 5 ,
the plurality of grooves are formed along a direction perpendicular to the axial direction of the screw rotor. 6. The liquid-cooled screw compressor according to claim 5 ,
the plurality of grooves are formed along directions inclined with respect to both the axial direction of the screw rotor and a direction orthogonal to the axial direction. 6. The liquid-cooled screw compressor according to claim 5 ,
a groove extending in the axial direction of the screw rotor is formed at a tip of the tip portion of the cartridge. 3. The liquid-cooled screw compressor according to claim 2 ,
The pair of liquid supply paths are formed symmetrically with respect to each other with the cartridge in between. 3. The liquid-cooled screw compressor according to claim 2 ,
The cross-sectional shape of the introduction path is circular,
the cartridge has a circular through-hole disposed in the introduction path;
an opening area of the through hole is equal to or larger than a flow path cross-sectional area of the introduction path.