WO2019239703A1 - Liquid-cooled gas compressor - Google Patents

Abstract

The compressor has a rotor and a main case for storing the rotor, wherein an inner wall of the main case has at least one pair of liquid supply holes for supplying liquid to the inside of the main case, and the distance from the central axis of the rotor to inner wall-side outlets of the liquid supply holes is equal to the distance from the central axis of the rotor to the inner wall, the pair of liquid supply holes having extending directions thereof intersecting inside the main case. According to this configuration, loss due to expansion during compression can be reduced, and the range of liquid scattering can be further increased, achieving a higher-performance collision-type particulate supply structure.

Description

Liquid-cooled gas compressor

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

The liquid-cooled gas compressor has (1) the purpose of lubrication between rotors when there are a plurality of rotors, compressor bodies, and rotors, and (2) from the working chamber whose volume decreases with the rotation of the rotor. The liquid is introduced into the compressor body for the purpose of sealing so that the gas does not leak and (3) the rotor heated by the compression heat of the gas and the purpose of cooling the gas.

As an effort to improve the performance of liquid-cooled gas compressors, changes in the timing of liquid supply, the temperature of liquid supply, the amount of liquid supply, etc. have been studied. In that study, a technique called fine particle supply has been devised. In fine oil supply, by supplying fine liquid into the compression chamber, the specific surface area of the liquid can be increased and heat can be effectively transferred to the liquid, thus improving the performance of the liquid-cooled gas compressor. Can do.

JP2003-184768

Patent Document 1 includes a pair of male screw rotors and female screw rotors, and a casing that accommodates the rotors, and first injects water into a compression working chamber formed by the pair of rotors and the casing. Forming a second water supply portion that forms a second water supply portion that injects water into the suction portion that communicates with the compression working chamber and sucks the working gas from the outside, and atomizes the water injected into the second water supply portion The water atomized by the atomizing means is sprayed on the intake air from the second water supply unit, and the average particle size of the water injected from the second water supply unit is set to the first particle size. The technique which made it smaller than the average particle diameter of the water sprayed from the water supply part of this is disclosed.
The structure disclosed in Patent Document 1 is a technique that achieves high performance by adopting a fine-particle supply mechanism in a water-lubricated compressor. There is a possibility that the water scattering range may be narrowed due to performance degradation due to expansion and expansion volume.

In order to solve the above problems, the rotor has a main case for storing the rotor, and the inner wall of the main case has at least one set of liquid supply holes for supplying liquid into the main case. The distance from the central axis to the outlet on the inner wall side of the liquid supply hole is equal to the distance from the central axis of the rotor to the inner wall, and the extension direction of each liquid supply hole intersects the inside of the main case. A compressor is provided.

By adopting the collision type fine particle supply structure of the present invention, the loss due to expansion during compression can be reduced, and furthermore, the range of liquid scattering can be expanded, so that a higher performance collision type fine particle supply structure is achieved. I can do it. Moreover, since it is not necessary to process the expansion volume part, the processing burden can be reduced.

An example of the figure which shows the collision type fine oil supply structure of the liquid cooling type gas compressor of Example 1 Sectional view of the liquid-cooled gas compressor of Example 1 shown in FIG. The figure which expanded the field of the code H of the collision type fine oil supply structure of the liquid cooling type gas compressor of Example 1 shown in Drawing 1B First example of a diagram showing an arrangement example of small-diameter oil hole sets Second example of the figure showing an example of arrangement of small-diameter oil hole sets 3rd example of the figure which shows the example of arrangement of small diameter oil hole group Example of diagram showing conventional structure of liquid-cooled gas compressor Sectional view of the conventional structure of the liquid-cooled gas compressor shown in FIG. The figure which expanded the field of the numerals B of the conventional structure of the liquid cooling type gas compressor shown in Drawing 3B Explanatory drawing of collision type fine liquid supply (side view) Explanatory diagram of collision type fine liquid supply (front view) First example of a diagram showing a conventional fine particle supply mechanism Second example of a diagram showing a conventional fine particle supply mechanism

Hereinafter, an embodiment of a twin screw type oil-cooled air compressor which is one form of the liquid-cooled gas compressor of the present invention will be described with reference to the drawings.

Prior to describing the embodiment of the present invention, the conventional structure of a twin screw oil-cooled air compressor will be described with reference to FIGS. 3A to 3C.

The twin screw oil-cooled air compressor accommodates a male rotor 1 and a female rotor 2 in a main case 3 and a D case 4, and the male rotor 1 is supported by an MS bearing 5 and an MD bearing 6. 2 is rotated by being supported by the FS bearing 7 and the FD bearing 8.

The space closed by the male rotor 1, the main case 3 and the D case 4 is the M-side working chamber 10, and the space closed by the female rotor 2, the main case 3 and the D case 4 is the F-side working chamber 11. Since the volume of each working chamber gradually decreases as the male rotor 1 and the female rotor 2 rotate, the pressure trapped in the air trapped in the working chamber increases, and the temperature rises.

The main purpose of oil supply in the oil-cooled air compressor is to seal the gap between the rotor constituting the working chamber and the main case 3 and D case 4 to reduce the leaked air, and the motor connected to the shaft of the male rotor 1 There are three types of lubrication to prevent wear and galling of the rotor when cooling the power transmitted to the male rotor 1 to the female rotor 2 through the rotor, and cooling described below.

In the case of the conventional oil-cooled air compressor, the lubricating oil is supplied to the M-side working chamber 10 and the F-side working chamber 11 from the oil-feeding hole 12 constituted by a simple round hole shown in FIG. It has become. The oil supplied to the working chamber spreads on the surface of the rotor and the case with the rotation of the rotor as power, and exchanges heat with the air compressed on the surface of the rotor and the case. If the temperature of the compressed air and the temperature of the oil are the same at the discharge part where the temperature of the compressed air is the highest, it can be said that the heat exchange with the oil was performed to the maximum. Contact was made only in a limited part such as the rotor and the case surface, and heat exchange was insufficient.

Therefore, as a method for increasing the contact area between compressed air and oil, it has been devised that heat is sufficiently exchanged by making the oil fine particles and increasing the specific surface area (surface area per unit volume). By making the oil into fine particles, the mass of the oil droplets (mass per droplet) is reduced, so that the effect that the oil stays in the working chamber for a long time and heat exchange becomes easier can be expected. Various methods have been devised, such as a single injection hole type and a swirl injection type, to pulverize the liquid, but the collision type is dominant in consideration of the pressure of the oil supplied into the working chamber and the simplicity of the structure. .

The collision type fine oil supply will be described with reference to FIGS. 4A and 4B. 4A and 4B are examples of diagrams simulating a model in which oil supplied from the oil supply path 9 is ejected from the two small-diameter oil supply holes 14 and collides in a predetermined range with the collision point 15 as the center.

The impacted oil is offset in the lateral momentum as seen from FIG. 4A (side view), and the downward momentum remains, and becomes a fan shape like the liquid film 17. Due to the surface tension of the oil, the liquid film becomes linear as it leaves the small-diameter oil supply hole 14, and then becomes a droplet 18. At this time, as the thickness of the oil as viewed from FIG. 4A (side view) becomes thinner, it can be scattered as oil having a smaller particle diameter at the tip. And as the particle size of the oil becomes smaller, the surface area per unit volume becomes larger as described above, so the heat exchange area with the compressed air can be increased, the cooling performance is improved, and the performance of the compressor can be improved. become.

A conventional structure of a liquid supply nozzle of an oil-cooled air compressor of collision type fine oil supply will be described with reference to FIGS. 5A and 5B. FIGS. 5A and 5B are a first example and a second example, respectively, illustrating the structure of the collision type fine oil supply nozzle. 5A and 5B, the structure of the oil-cooled air compressor is the same as that shown in FIGS. 3A and 3B, and the structure of the portion shown in FIG. 3C (detail B) is different.

FIG. 5A shows a structure in which the oil supply nozzle 13 is fitted in the oil supply path 9, and the tip of the oil supply nozzle 13 is arranged so as not to protrude from the inner wall of the main case 3 in which the rotors 1 and 2 are stored. Yes. The structure of the oil supply nozzle 13 is a structure in which small-diameter oil supply holes 14 are formed in two locations, and the oil ejected from the small-diameter oil supply holes 14 is processed so as to collide at the collision point 15. .

FIG. 5B shows that after providing an oil supply path 9 so as not to penetrate from the outer wall of the main case 3 in the direction of the inner wall, a substantially right-angled V-shaped groove is provided on the inner wall of the main case 3, and small diameter oil supply is provided in the V-shaped groove. The hole 14 has a structure in which holes are drilled at two locations, and the oil ejected from the small-diameter oil supply hole 14 is processed so as to collide at the collision point 15.

In both FIGS. 5A and 5B, the oil exchange can improve the heat exchange efficiency as compared with the simple round hole, but there is a concern that the compression efficiency may be lowered in that the expansion volume 16 is formed on the inner wall of the main case 3. The The reason why the expansion volume 16 is formed is that a gap is generated when the oil supply nozzle 13 is fitted into the main case 3 in the structure of FIG. 5A, and two small-diameter oil supply holes are processed in both the structures of FIGS. It is mentioned before that a hollow part is processed in order to ensure the right angle surface of the hole processing.

In the structure of FIGS. 5A and 5B, the oil scattering shape may become narrow because the collision point 15 is close to a structure such as the oil supply nozzle 13 or the inner wall of the main case 3. This is because the oil being scattered comes into contact with structures such as the oil supply nozzle 13 and the edge of the inner wall of the main case 3 (the front and back sides of the paper surface), and the scattering range becomes narrower. It is thought that there is a factor that the scattering range is narrowed by narrowing the air flow passage around the air.

Further, particularly in the structure of FIG. 5A, there is a problem in that the oil scattering angle cannot be controlled because the mounting angle of the oil supply nozzle 13 varies depending on the tightening degree.

The structure of the liquid supply nozzle of the oil-cooled gas compressor of the collision type fine oil supply according to the present embodiment is a structure developed for the purpose of solving the concerns in FIGS. 5A and 5B.

1A to 1C are diagrams showing an example of a collision type fine oil supply structure of an oil-cooled gas compressor in the present embodiment. Since the structure of the oil-cooled gas compressor is the same as that described with reference to FIGS. 3A to 3C, description thereof will be omitted.

1A to 1C show an example in which one set of small-diameter oil supply holes 14 is provided in each of the male rotor 1 and the female rotor 2, but in this embodiment, the set of small-diameter oil supply holes 14 is one set. Further, the place where the small-diameter oil supply hole 14 is arranged is not limited to the position illustrated in FIGS. 1A to 1C. That is, a plurality of oil supply paths 9A may be provided so as to branch from one oil supply path 9B, and a plurality of sets of small-diameter oil supply holes 14 communicating with each oil supply path 9A may be provided.

The oil supply path 9B communicates with an oil sump (not shown). The oil sump contains oil separated from compressed air discharged from an oil-cooled gas compressor, MS bearing 5, MD bearing 6, FS bearing 7, and FD bearing. The oil supplied to 8 etc. is stored. The oil stored in the oil reservoir is transported by the pressure of the compressed air and supplied to the oil supply path 9B via an oil cooler or the like.

The collision type fine oil supply structure in the present embodiment is provided with the oil supply passages 9A and 9B so as not to penetrate the working chambers 10 and 11 from the outside of the main case 3, and then the main case 3 is directly processed to make a small diameter oil supply hole. 14 differs from the configuration of FIGS. 5A and 5B in that 14 is formed.

In other words, the collision type fine oil supply structure of the present embodiment is expressed by the distance from the central shafts 1a and 2a of the rotors 1 and 2 to the inner wall of the main case 3, and the small diameter from the central shafts 1a and 2a of the rotors 1 and 2. The distance from the oil supply hole 14 to the outlet 19 is the same. The outlet 19 of the small-diameter oil supply hole 14 indicates a surface connecting the edges of the holes provided in the inner wall of the main case 3 indicated by the opening parenthesis in FIG. 1C. The outlet 19 of the small-diameter oil supply hole 14 in FIGS. 5A and 5B is different from the outlet 19 of the small-diameter oil supply hole 14 of the present embodiment in that the distance from the central axes 1a and 2a is longer than the inner wall of the main case 3. different.

Since the expansion volume 16 is a space generated when the outlet 19 of the small-diameter oil supply hole 14 is located farther from the central axes 1a and 2a than the inner wall of the main case 3, this structure allows the collision type fine particles of this embodiment to be used. The expansion volume 16 is not formed in the oil supply structure, and a reduction in compression efficiency due to expansion and recompression of compressed air can be prevented.

Further, in this structure, the collision point 15 where the oil ejected from the two small-diameter oil supply holes 14 collides inevitably exists on the central shafts 1a and 2a side with respect to the inner wall of the main case 3. For this reason, the structure is in the axial direction of the collision point 15 (the vertical direction in FIG. 1A) and the radial direction including the collision point 15 (a point having a distance equal to the distance from the central axis 1a, 2a to the collision point 15). It is not present except for the rotors 1 and 2, and the point that the oil scattering shape concerned in FIGS. 5A and 5B becomes narrower is improved.

As described above, the structure of the liquid supply nozzle in the present embodiment can cool the compressed air more efficiently than the structure of FIGS. 5A and 5B, and can eliminate the concern of a decrease in compression efficiency.

Next, the relationship between the two small-diameter oil supply holes 14 and the axial directions of the rotors 1 and 2 will be described using the example of FIGS. 2A to 2C. FIGS. 2A to 2C are first to third examples in which the portions where the small-diameter oil hole sets 20, 21, and 22 provided in the main case 3 are disposed are viewed from the axial direction of the rotors 1 and 2. FIG. The illustrated alternate long and short dash line indicates the tooth tips of the rotors 1 and 2, and the dotted line extending from the small-diameter oil supply hole 14 indicates the small-diameter oil supply hole 14 extending in the direction opposite to the paper surface.

The small-diameter oil supply hole 14 has a cylindrical shape with a circular cross section, but is provided with an inclination with respect to the inner wall of the main case 3 and thus has an elliptical shape in the top view. More specifically, since the inner wall of the main case 3 has a cylindrical shape for storing the rotors 1 and 2, it has a shape different from a strict ellipse.

2A is an example in which the straight line connecting the small diameter oil supply holes 14 is parallel to the axial direction of the rotors 1 and 2, and the small diameter oil supply hole set 21 shown in FIG. 2B is vertical. Further, in the small diameter oil supply hole set 22 shown in FIG. 2C, a straight line connecting the small diameter oil supply holes 14 is perpendicular to the tooth tips of the rotors 1 and 2. As described with reference to FIGS. 4A and 4B, the oil ejected from the small-diameter oil supply hole 14 and collided at the collision point 15 spreads perpendicularly to the straight line connecting the small-diameter oil supply holes 14 to form the liquid film 17. By arranging the small-diameter oil supply hole 14 as in the small-diameter oil supply hole set 22, the liquid film 17 can be prevented from colliding with the tooth tip, and more droplets 18 can be supplied into the working chambers 10 and 11. .

2A to 2C show the arrangement of three patterns of small-diameter oil supply hole groups, but the relationship between the axial direction of the rotors 1 and 2 and the small-diameter oil supply hole groups is not limited to these three patterns. Oil droplets 18 can be produced at Further, one pattern of small-diameter oil hole sets may be provided for one main case 3, or a plurality of patterns of small-diameter oil hole groups may be provided. For example, when the small-diameter oil supply hole set 22 is adopted, a small-diameter oil supply hole set corresponding to the angle of the blade edge of each rotor is provided on the inner wall of the main case 3 on the male rotor 1 side and the inner wall of the main case 3 on the female rotor 2 side. Can do.

In this embodiment, a twin screw type oil cooled air compressor, which is one form of a liquid cooling type gas compressor, has been described as an example. However, the present invention is not limited to the twin screw type, but a single screw type or 3 Even a screw type compressor having two or more rotors, or another type of compressor not using a screw, can be applied as long as it is a compressor that jets oil into the compression chamber. In the present invention, the refrigerant is not limited to oil, and water or other liquid may be ejected into the casing. Furthermore, the gas to be compressed is not limited to air, and can be applied to a compressor that targets other gases such as nitrogen gas, hydrocarbon gas, and hydrogen gas.

In addition, this invention is not limited to the above-mentioned Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of a certain embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

1: Male rotor 1a: Center shaft 2: Female rotor 2a: Center shaft 3: Main case 4: D case 5: MS bearing 6: MD bearing 7: FS bearing 8: FD bearing 9: Oil supply path 10: M side working chamber 11: F side working chamber 12: oil supply hole 13: oil supply nozzle 14: small diameter oil supply hole 15: oil supply collision point 16: expansion volume 17: liquid film 18: oil droplet 19: inner wall side outlets 20 and 21 of the small diameter oil supply hole , 22: Small diameter oil hole assembly

Claims (4)

1. The rotor,
   A main case for storing the rotor,
   The inner wall of the main case has at least one set of liquid supply holes for supplying liquid into the main case.
   A compressor in which a distance from a central axis of the rotor to an inner wall side outlet of the liquid supply hole is equal to a distance from the central axis of the rotor to the inner wall.
2. 2. The compressor according to claim 1, wherein each of the one set of liquid supply holes intersects in an extending direction of each liquid supply hole inside the main case.
3. The compressor according to claim 1, wherein the pair of liquid supply holes are arranged so that a straight line connecting the pair of liquid supply hole outlets is substantially perpendicular to a tooth tip of the rotor.
4. A liquid supply path for supplying liquid to the liquid supply hole;
   The compressor according to claim 1, wherein a plurality of sets of liquid supply holes communicate with the liquid supply path.

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