JP2003083272A - Screw compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an efficient and compact screw compressor with built-in an oil separating mechanism. SOLUTION: This screw compressor has a cyclone separator as an oil separating means and a swirl strengthening plate is provided on an outer circumference part of a cyclone inner tube. The swirl strengthening plate is positioned below a lower end of a gas introducing passage and does not range a whole outer circumference. Gas and oil flowing into the cyclone separator turn down along a cyclone outer wall and oil adheres on the cyclone outer wall and is separated from gas by difference of centrifugal force due to difference of density. The swirl strengthening plate can prevent flow flowing in the cyclone separator from widely spreading in the vertical direction right after flowing in. Consequently, degradation of centrifugal separation effect due to reduction of swirl flow speed can be prevented to maintain high separating efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw compressor, and more particularly to a screw compressor for a refrigerant used for refrigeration and air conditioning, which is small in size and suitable for reducing oil carry-out to the outside of the screw compressor. It is about.

[0002]

2. Description of the Related Art In a screw compressor for refrigerant and an oil-cooled screw compressor for air, oil is supplied to a bearing and a compression chamber for the purpose of lubrication, sealing of a gap and cooling. The supplied oil is discharged from the compression chamber through the discharge port together with the compressed gas, so it is necessary to separate and collect it and prepare for supply again.

In a screw compressor for a refrigerant, Japanese Patent Application Laid-Open No. 10-159763 (referred to as a first conventional example).
An oil separation chamber is provided downstream of the discharge port, and the oil is separated from the refrigerant gas by passing through a wire mesh demister provided in the chamber. It is shown that the separated oil drops by gravity into an oil sump in the lower part of the oil separation chamber, is returned to the oil sump in the lower part of the main casing communicating with the oil sump, and is supplied to the bearing again.

Further, in the air compressor, Japanese Patent Laid-Open No. 7-24
As described in Japanese Patent No. 3391 (referred to as a second conventional example), in order to separate oil contained in air, a method of providing a cyclone type separation mechanism downstream of a discharge port is generally used.

[0005]

The method of separating oil from the refrigerant gas by passing through the wire mesh demister in the first conventional example used in the refrigerant screw compressor has a high separation efficiency when the passage speed of the refrigerant gas is high. It has the property of decreasing.
Therefore, unless the passage cross-sectional area is made large and the flow velocity is made as slow as possible, sufficient separation efficiency cannot be obtained, and the oil separation chamber inevitably becomes large. Therefore, miniaturization by this method has a difficult problem.

Further, the cyclone system used in the air compressor of the second conventional example separates oil and refrigerant gas by centrifugal force by utilizing the density difference of gas and liquid in the outer wall of the cyclone. It is composed of a swirling part for generating a flow and a part which becomes a returning rising flow from the downward swirling flow to the cyclone inner cylinder, and a part for storing the separated oil is provided in the lower part. The amount of oil stored in the lower part must be secured for the operation of the compressor, and accordingly, the amount of oil inevitably increases in the vertical direction. Therefore, the cyclone method can be made more compact in the radial direction than the wire mesh demister method,
There was a problem that it became large in the vertical direction.

An object of the present invention is to solve the above problems of the prior art and to provide a compact screw compressor which realizes a compact and highly efficient oil separation mechanism.

[0008]

In order to achieve the above object, a screw compressor according to the present invention is characterized by what is stated in each of the claims.

That is, a screw compressor according to the invention as claimed in claim 1 as an independent claim is such that at least a pair of screw rotors, which are a male screw rotor and a female screw rotor meshing with each other, a motor for driving the screw rotor, and the screw. A shaft support means for rotatably supporting the rotor, a casing accommodating them and forming a discharge port, and a gas introduction flow path from the discharge port are provided tangentially to generate a downward swirling flow. Cyclone type oil separating means comprising an outer wall of the cyclone, a cyclone inner cylinder for generating an upward ascending flow from the swirling flow, and an oil reservoir formed below the cyclone inner cylinder, and the cyclone. Type oil separating means collects and collects the oil to the shaft supporting means and the screw rotor. In a screw compressor provided with an oil supply flow path for supplying, there is a gap between the cyclone inner cylinder outer circumference and the cyclone outer wall in the radial direction, and the gas introduction flow path lower end in the circumferential direction. It is characterized in that a plate-like swirl flow strengthening plate is provided in a range that does not reach the entire circumference, starting from the lower side.

A screw compressor according to a second aspect of the present invention, which is an independent claim, includes at least a pair of screw rotors, which are a male screw rotor and a female screw rotor meshing with each other, a motor for driving the screw rotor, and the screw. A shaft support means for rotatably supporting the rotor, a casing accommodating them and forming a discharge port, and a gas introduction flow path from the discharge port are provided tangentially to generate a downward swirling flow. Cyclone type oil separating means comprising an outer wall of the cyclone, a cyclone inner cylinder for generating an upward ascending flow from the swirling flow, and an oil reservoir formed below the cyclone inner cylinder, and the cyclone. Supplying the oil separated and collected by the hydraulic oil separation means to the shaft support means and the screw rotor In the screw compressor provided with an oil supply passage, the space inside the cyclone inner cylinder is vertically partitioned in the circumferential direction to prevent the upward flow in the circumferential direction. It is characterized in that a rectifying plate for the purpose is provided.

[0011]

In order to solve the above problems, the present invention adopts a cyclone system as an oil separator. Similar to the conventional example, an oil sump is formed in the lower part of the oil separator, but because the separation is better than in the conventional example, the oil rise amount is reduced, so the distance between the lower end of the inner cylinder and the oil sump oil surface is Even if the number increases, it does not change much as a whole, so it may be closer than the conventional example. The outer peripheral portion of the inner cylinder is provided with a plate-shaped member extending in the radial direction, and the range thereof does not reach the entire outer periphery. The plate-shaped member is preferably located below the lower end of the gas introduction flow path.

Further, as another means, a current plate is provided so as to partition the space inside the cyclone inner cylinder in the circumferential direction and vertically. This straightening vane may be composed of a plurality of sheets, and it is better to be positioned so as to penetrate the central portion of the inner cylinder.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention is shown in FIG.
A description will be given with reference to 2, 3 and 4.

As shown in FIG. 1, the refrigerant cycle is composed of a compressor 1, a condenser 2, an expansion valve 3 and an evaporator 4 in this order to form a circulation cycle.

The oil supplied to lubricate the bearings and the screw rotor inside the compressor 1 is not only useless in the refrigerant cycle, but also causes harm. When a large amount of oil is mixed in the refrigerant gas, it hinders heat exchange in the condenser 2 and the evaporator 4, increases pressure loss in the pipes, and deteriorates the performance of the entire refrigerant cycle. Further, if a large amount of oil comes out of the compressor 1 in the refrigerant cycle, the amount of oil held inside the compressor 1 decreases, and it becomes difficult to lubricate the compressor 1 itself. Therefore, it is necessary to efficiently separate the oil from the refrigerant gas before leaving the compressor 1.

The structure of the compressor 1 of this embodiment will be described with reference to FIGS. The compressor 1 is entirely covered with a casing, and the casing has a three-part structure like the main casing 11, the discharge casing 12, and the suction casing 13 in order to facilitate disassembly and assembly and manufacturing.

The suction casing 13 is provided with a gas inlet 31 for guiding the refrigerant gas from the outside to the main body of the compressor 1. The main casing 11 contains a motor 14 as a driving electric motor and a pair of screw rotors including a male screw rotor 15 and a female screw rotor 16.

The compression chamber is composed of both screw rotors 15 and 16
The tooth grooves of are meshed with each other and are surrounded and formed by the bore wall formed in the main casing 11, the suction side end surface, and the discharge side end surface formed in the discharge casing 12. The rotor of the motor 14 is fixed to the extended portion of the shaft of the male screw rotor 15. Both screw rotors 15 and 16
Is rotatably supported by a suction side bearing 17 as a shaft supporting means held in the main casing 11 and a discharge side bearing 18 as a shaft supporting means held in the discharge casing 12.

A slide valve 19 is provided above both screw rotors 15 and 16 in the main casing 11, and the slide valve 19 is moved by the hydraulic pressure acting on the piston 20 in the discharge casing 12 to control the flow rate of the refrigerant gas. To do. A radial discharge port 21 is formed in the slide valve 19 and an axial discharge port 22 is formed in the discharge casing 12 to serve as a communication passage to the discharge passage of the compression chamber that has completed compression. A space called a discharge chamber 23 is provided in order to secure a region where the slide valve 19 moves downstream of these discharge ports 21 and 22 and to connect both discharge ports 21 and 22 having a complicated shape and a flow path having a simple shape.

The discharge casing 12 has a cyclone separator 25 as a cyclone type oil separating means and an oil sump chamber 32.
And are integrally formed. The cyclone separator 25 includes a cyclone outer wall 26, a cyclone inner cylinder 27, an upper lid 28, and a swirl flow strengthening plate 29, and the gas introduction flow path 24 from the discharge chamber 23 to the cyclone separator 25 has the same discharge casing 12 as well.
Form inside. The swirl flow strengthening plate 29, which is fixed to the outer peripheral portion of the cyclone inner cylinder 27 by welding, is located below the lower end of the gas introduction flow path 24. The swirl flow strengthening plate 29 does not extend over the entire outer circumference, but is provided at least in a range of a quarter or more of the outer circumference of the cyclone inner cylinder 27 as viewed from above starting from the lower part of the gas introduction flow path 24. Also, the swirl flow strengthening plate 2
A gap 36 is provided between the outer wall 9 and the outer wall 26 of the cyclone. The cyclone inner cylinder 27 and the upper lid 28 are an integral member and are fastened to and integrated with the upper portion of the cyclone outer wall 26. A gas outlet 30 which is an outlet of the compressor 1 is formed in the upper portion of the cyclone inner cylinder 27.

The gas introduction flow path 24 does not necessarily have to be in the above-mentioned direction, and the turning is not always clockwise when viewed from above.

The screw compressor according to the first embodiment having the above-described structure operates as follows.

The motor 14 is driven by electric power supplied from the outside.
Generates rotational power, and when the male screw rotor 15 having a common axis is rotationally driven, the meshed female screw rotor 16 is rotationally transmitted to the male screw rotor 15.
While compressing the compression chamber formed by both screw rotors 15 and 16 and the bore and the like in the axial direction, the volume of the compression chamber is expanded and reduced, and the refrigerant gas sucked and confined therein is compressed and discharged.

The refrigerant gas passes through the gas inlet 31 from the outside, enters the inside of the screw compressor 1, passes through the gap and the outer periphery of the motor 14, and then both screw rotors 15 and 1
It is sucked into the compression chamber from the suction port formed mainly in the lower part of 6. The discharge oil of the suction side bearing 17 is mixed with the flow of the refrigerant gas before being sucked, and the discharge oil of the suction side bearing 17 and the discharge side bearing 18 is supplied in the compression process.

After the compression is completed, the refrigerant gas and the oil mixed in the refrigerant gas are discharged into the discharge ports 21 and 22 which are the openings of the compression chamber.
Exits from the outlet, flows through the gas introduction flow path 24 through the discharge chamber 23, and enters the cyclone separator 25. Gas introduction channel 24
Is tangentially connected to the cyclone outer wall 26, the refrigerant gas flowing into the cyclone separator 25 is
It descends while turning clockwise along the cyclone outer wall 26 when viewed from above. The refrigerant gas that swirls and descends along the cyclone outer wall 26 folds back between the lower end of the cyclone inner cylinder 27 and the oil sump oil surface 35, and ascends the cyclone inner cylinder 27 while swirling, and exits from the gas outlet 30 to the outside. Sent out.

In this process, the oil gradually approaches the outer circumference due to the difference in the centrifugal force caused by the difference in density with the refrigerant gas,
The cyclone is attached to the inner surface of the outer wall 26 and separated. The oil attached to the inner surface of the cyclone outer wall 26 flows down by gravity and is stored in the oil sump chamber 32.

Without the swirl flow strengthening plate 29, the flow flowing into the cyclone separator 25 spreads in the vertical direction immediately after the inflow, and the swirling flow velocity decreases significantly. Therefore, the effect of centrifugation is weakened, and high separation efficiency cannot be expected. But,
If the swirl flow strengthening plate 29 is provided, the flow flowing into the cyclone separator 25 is blocked by the swirl flow strengthening plate 29 and does not greatly spread in the vertical direction immediately after the inflow, so that a decrease in swirl flow velocity can be suppressed. Therefore, it is possible to prevent the effect of centrifugation from being lowered, and it is possible to achieve high separation efficiency.

Of the oil separated by the cyclone separator 25, the oil separated above the swirl flow strengthening plate 29 and attached to the cyclone outer wall 26 is the swirl flow strengthening plate 29 and the outer wall 26.
Flowing down from a gap 36 provided between the oil collecting chamber 32 and
Stored in. Therefore, the oil once separated and adhered to the cyclone outer wall 26 does not adhere to the swirl flow strengthening plate 29 when flowing down the cyclone outer wall 26, and is again carried by the flow of the refrigerant gas to be carried outside.

The discharge pressure of the compressor 1 acts on the oil stored in the oil sump chamber 32, while the bearings 17, 18
The neighborhood is almost under suction pressure. Therefore, the oil flows through the oil supply flow path 33 connecting the two positions to the bearing 17, due to the pressure difference.
18 are supplied. The oil enters the compression chamber after being used for lubrication and cooling of the bearings 17, 18 and both screw rotors 15, 16, and then lubricates the screw rotors 15 and 16 with each other, seals between the compression chambers, and cools against compression heat. Acts as a material. After this, the oil is again discharged together with the refrigerant gas and enters the cyclone separator 25, so that the oil circulates inside the compressor 1.

In the embodiment described above, the structure is such that the male screw rotor 15 is driven by the motor 14 provided at one end of the male screw rotor 15 and the rotation is transmitted from the male screw rotor 15 to the female screw rotor 16. , The motor 14 is provided at one end of the female screw rotor 16 so that the female screw rotor 16 is connected to the male screw rotor 1.
The rotation may be transmitted to No. 5.

A second embodiment of the present invention will be described with reference to FIGS. The overall structure of the screw compressor is the first
Since it is the same as the embodiment described above, only the periphery of the cyclone separator 25 will be described.

The cyclone separator 25 and the oil sump chamber 32 are integrally formed in the discharge casing 12. The cyclone separator 25 includes a cyclone outer wall 26 and a cyclone inner cylinder 2
7, the upper lid 28, and the current plate 34, and the gas introduction flow path 24 from the discharge chamber 23 to the cyclone separator 25 is also formed inside the same discharge casing 12. The current plate 34 is welded to the inside of the cyclone inner cylinder 27, and is provided so as to partition the inside of the cyclone inner cylinder 27 with a vertical plate in the circumferential direction. The cyclone inner cylinder 27 and the upper lid 28 are an integral member and are fastened to and integrated with the upper portion of the cyclone outer wall 26. At the upper part of the cyclone inner cylinder 27, a gas outlet 30 serving as an outlet of the compressor 1 is provided.
To form.

The screw compressor according to the second embodiment having the above-mentioned construction operates as follows.

The refrigerant gas after the completion of compression and the oil mixed in the refrigerant gas are discharged into the discharge ports 21 and 22 which are the openings of the compression chamber.
Exits from the outlet, flows through the gas introduction flow path 24 through the discharge chamber 23, and enters the cyclone separator 25. Gas introduction channel 24
Is tangentially connected to the cyclone outer wall 26, so that the gas flowing into the cyclone separator 25 descends while swirling clockwise along the cyclone outer wall 26 when viewed from above.

The gas introduction flow path 24 does not necessarily have to be in the above direction, and the turning is not always clockwise when viewed from above.

In this process, the oil gradually approaches the outer circumference due to the difference in the centrifugal force caused by the difference in density with the refrigerant gas,
The cyclone is attached to the inner surface of the outer wall 26 and separated. The oil attached to the inner surface of the cyclone outer wall 26 flows down by gravity and is stored in the oil sump chamber 32.

The refrigerant gas swirls and descends along the cyclone outer wall 26, and the lower end of the cyclone inner cylinder 27 and the oil sump oil surface 3
It turns back between 5 and becomes an ascending flow, and is sent out of the compressor 1 from the gas outlet 30 through the cyclone inner cylinder 27 in which the current plate 34 is provided. For example, the rectifying plate 34 in the shape of a cross plate suppresses the upward flow from swirling, so that the generation of a tornado flow and the pressure drop in the central portion of the upward flow can be prevented. Therefore, the oil once separated and stored in the oil sump chamber 32 is
It is possible to prevent the oil from being taken away from the oil sump oil surface 35 and flowing out to the outside of the compressor 1 due to the generation of a tornado flow or the pressure drop in the central portion of the ascending flow.
High separation efficiency can be maintained even near the lower end of.

[0038]

According to the present invention, it is possible to realize a screw compressor equipped with a compact oil separation mechanism having high separation efficiency. Further, by reducing the carry-out amount of oil mixed in the refrigerant gas from the compressor, there is also an effect that the performance of the refrigeration cycle equipped with the present compressor is improved. Furthermore, by securing a sufficient amount of oil in the compressor, the reliability of the compressor can be maintained high.

[Brief description of drawings]

FIG. 1 is a system diagram of a refrigeration cycle.

FIG. 2 is a vertical cross-sectional view of the screw compressor according to the first embodiment of the present invention.

3 is a longitudinal sectional view of the screw compressor according to FIG. 2 in a direction perpendicular to FIG.

4 is a cross-sectional view of the screw compressor according to FIG.

FIG. 5 is a vertical sectional view of a screw compressor according to a second embodiment of the present invention.

6 is a cross-sectional view of the screw compressor according to FIG.

[Explanation of symbols]

11 ... Main casing 12 ... Discharge casing 13 ... Inhalation casing 14 ... Motor 15 ... Male screw rotor 16 ... Female screw rotor 17 ... Bearing on intake side 18 ... Discharge side bearing 21 ... Radial discharge port 22 ... Axial discharge port 23 ... Discharge chamber 24 ... Gas introduction flow path 25 ... Cyclone separator 26 ... Cyclone outer wall 27 ... Cyclone inner cylinder 28 ... Top lid 29 ... Swirl flow strengthening plate 30 ... Gas outlet 31 ... Gas inlet 32 ... Oil sump chamber 33 ... Oil supply channel 34 ... Current plate 35 ... Oil sump oil level 36 ... Gap

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hirotaka Kamiya             502 Kintatemachi, Tsuchiura City, Ibaraki Japan             Tate Seisakusho Mechanical Research Center (72) Inventor Shigekazu Nozawa             Hitachi, Ltd. 390 Muramatsu, Shimizu City, Shizuoka Prefecture             Air conditioning system Shimizu Production Headquarters (72) Inventor Masayuki Urashin             Hitachi, Ltd. 390 Muramatsu, Shimizu City, Shizuoka Prefecture             Air conditioning system Shimizu Production Headquarters (72) Inventor Takeshi Hida             Hitachi, Ltd. 390 Muramatsu, Shimizu City, Shizuoka Prefecture             Air conditioning system Shimizu Production Headquarters (72) Inventor Hiroki Osumi             Hitachi, Ltd. 390 Muramatsu, Shimizu City, Shizuoka Prefecture             Air conditioning system Shimizu Production Headquarters F term (reference) 3H029 AA03 AA11 AA15 AB03 BB05                       BB35 BB43 CC09 CC25 CC34                       CC42 CC45 CC55 CC58                 4D031 AC04 BA03 EA01                 4D053 AA01 AB01 BA01 BB07 BC01                       BD04 CB14 CD23 DA10

Claims (3)

[Claims] 1. A pair of screw rotors comprising a male screw rotor and a female screw rotor meshing with each other, a driving motor for the screw rotors, and a shaft support means for rotatably supporting the screw rotors.
A casing that accommodates them and forms a discharge port, a cyclone outer wall in which a gas introduction flow path from the discharge port is provided tangentially to generate a downward swirl flow, and from the swirl flow upward And a cyclone type oil separation means composed of a cyclone inner cylinder and an oil sump chamber formed below the cyclone inner cylinder, and oil collected and separated by the cyclone type oil separation means is supported by the shaft support. Means and an oil supply flow path for supplying to the screw rotor, in the outer periphery of the cyclone inner cylinder, having a gap between the cyclone outer wall in the radial direction, in the circumferential direction A screw characterized in that a plate-like swirling flow reinforcing plate is provided in a range that does not reach the entire circumference, starting from below the lower end of the gas introduction channel. Compressor. 2. A pair of screw rotors comprising a male screw rotor and a female screw rotor that mesh with each other, a driving motor for the screw rotors, and a shaft support means for rotatably supporting the screw rotors.
A casing that accommodates them and forms a discharge port, a cyclone outer wall in which a gas introduction flow path from the discharge port is provided tangentially to generate a downward swirl flow, and from the swirl flow upward And a cyclone type oil separation means composed of a cyclone inner cylinder and an oil sump chamber formed below the cyclone inner cylinder, and oil collected and separated by the cyclone type oil separation means is supported by the shaft support. Means and an oil supply flow path for supplying to the screw rotor, in the cyclone inner cylinder, the space inside the inner cylinder is partitioned vertically in the circumferential direction, and a circle of the upward flow. A screw compressor provided with a straightening vane for preventing circumferential flow. 3. A cyclone inner cylinder is provided with a straightening plate for partitioning a space inside the inner cylinder perpendicularly to the circumferential direction to prevent the upward flow in the circumferential direction. The screw compressor according to claim 1.