JP2002070778A - Screw compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screw compressor small in size of which an oil separating mechanism (ability) is made to have high efficiency. SOLUTION: In the screw compressor, wherein bearing members 17, 18 supporting the axis of screw rotors 15, 16 which are made to rotate them freely, a casing 11 containing these components, a discharging casing 12 by which a discharging port 2 of the casing 11 is formed, an oil separating unit is put in the down stream of the discharging port 2, an oil supplying flow passage 33 which supplies the oil, which is separated and recovered from the oil separating unit, to the bearing members 17, 18, there are provided an oil separating unit which is called as a cyclon 25 formed in the discharging casing 12, and an oil reservior 31 formed under the cyclon 25.

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 suitable for a small-sized, high-performance, and low oil take-out.

[0002]

2. Description of the Related Art In a screw compressor for a refrigerant used for refrigeration and air conditioning, an oil separation chamber is provided downstream of a discharge port, oil is separated from refrigerant gas in the oil separation chamber, and the separated oil is supplied to a lower portion of the oil separation chamber. Drop it by gravity into the oil sump and return to the oil sump in the lower part of the main casing,
It is known that the bearing is supplied to the bearing again.
No. 1,597,763.

Japanese Patent Application Laid-Open No. Hei 7-243391 discloses that two stages of a cyclone and a filtration system (or a collection filter system) are used in order to obtain a high separation efficiency.

[0004]

In the above-mentioned prior art, a coarse mesh oil separation element must be used in order to suppress the pressure loss to a small value. If the discharge chamber is not enlarged, sufficient separation efficiency is obtained. Could not be obtained.

[0005] Further, in the case of using two-stage oil separating means, there is a possibility that the size becomes large as a whole, the vibrating portion vibrated by the pulsation of the discharge pressure increases, and the generated noise increases. Furthermore, high-temperature oil separated immediately after discharge flows into the oil sump provided in the lower part of the main casing during operation of the compressor, and the high-temperature oil is separated from the refrigerant gas in the suction process by one wall. Therefore, heat is transmitted through the wall surface, and the refrigerant gas is heated, which is one of the causes of performance degradation.

An object of the present invention is to solve the above-mentioned problems of the prior art, to realize a highly efficient oil separation mechanism, and to realize a small screw compressor. Another object of the present invention is to improve compressor performance (energy efficiency) and to suppress noise generation.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a screw rotor, a shaft supporting means for rotatably supporting the screw rotor, a casing for accommodating them, and a discharge port of the casing. Discharge casing, and an oil separation means provided downstream of the discharge port, and a screw compressor having an oil supply flow path for supplying oil separated and recovered by the oil separation means to the shaft support means. It is provided with oil separating means formed as a cyclone formed in the discharge casing, and an oil reservoir formed below the cyclone.

[0008] In the above, it is desirable that an introduction flow path from the discharge port to the cyclone is formed in the discharge casing.

Further, in the above, it is desirable that the oil supply passage is formed in the discharge casing and extends from a lower portion of the oil reservoir to the shaft support means.

Further, in the above, it is desirable that the cyclone has a cyclone outer wall and an inner cylinder, and the inner cylinder has a gas outlet.

Further, the present invention relates to a screw compressor including a screw rotor, a shaft supporting means for rotatably supporting the screw rotor, and a discharge casing.
It is provided with a cyclone formed in the discharge casing, and a filtration type oil separation means provided downstream of the cyclone.

Furthermore, in the above, it is desirable that a recovery flow path for the oil separated by the filtration type separation means is formed inside the discharge casing.

Further, the present invention provides a screw rotor, a casing for rotatably supporting and housing the screw rotor, and a screw compressor element having a discharge port in the casing.
In a screw compressor provided with oil separating means downstream of the discharge port, a primary separating means formed in a discharge casing and utilizing the density difference and inertia of a gas to be compressed and oil, such as a cyclone method or a collision method, and filtration. An oil separating means constituted by a secondary separating means, a main oil sump formed below the primary separating means, and a main oil sump are separated by partition walls;
The secondary oil reservoir has a sub oil reservoir formed at a lower portion thereof, and the main oil reservoir and the sub oil reservoir have an oil communication passage communicating with the lower portion.

Furthermore, in the above, it is desirable that the primary separation means is a cyclone.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. The refrigerant cycle includes a compressor 1, a condenser 2, an expansion valve 3, and an evaporator 4 in this order, and forms a circulation path (cycle). Since the compressor 1 plays a role of compressing and sending the refrigerant gas therein, it is desired that the energy efficiency (performance) as the gas compression work for the input energy be high.

The oil used for lubrication inside the compressor is not only unnecessary in the refrigerant cycle, but also impedes heat exchange in the condenser 2 and the evaporator 4 when mixed in a large amount with the refrigerant gas. Also, if a large amount of oil comes out of the refrigerant cycle, the amount of oil held inside the compressor decreases, and lubrication of the compressor itself becomes difficult. Thus, it is necessary to separate the oil from the refrigerant gas before exiting the compressor.

In FIG. 1, the compressor 1 is entirely covered with a casing, and the casing is divided into three parts such as a main casing 11, a discharge casing 12, and a suction casing 13 to facilitate disassembly and assembly. The suction casing 13 is provided with a gas inlet 29 for guiding the refrigerant gas from outside to the compressor body.

A motor 14 and a pair of screw rotors (male rotor 15 and female rotor 16) are built in the main casing 11, and the tooth grooves of the rotors 15 and 16 are engaged with each other.
Surrounded by a bore wall and a suction side end face formed in the main casing 11, and a discharge side end face formed in the discharge casing 12,
Form a compression chamber. The rotor of the motor 14 is a male rotor 15
Fix the shaft to the extended part. The rotors 15 and 16 are supported by a suction-side bearing 17 held by the main casing 11 and a discharge-side bearing 18 held by the discharge casing 12.

The two rotors 15, 16 in the main casing 11
A slide valve 19 is provided on the upper part, and the slide valve 19 is moved by hydraulic pressure acting on a piston 20 in the discharge casing 12 to control the flow rate of the refrigerant gas. 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 so as to be a communication path to the discharge flow path of the compression chamber that has completed compression. A space called a discharge chamber 23 is provided in order to secure an area where the slide valve 19 moves downstream of these discharge ports and to connect both discharge ports having a complicated shape and a flow path having a simple shape.

A cyclone separator 25 is integrated with the discharge casing 12 by casting. The cyclone separator 25 includes a cyclone outer wall 26 and an inner cylinder 27, a bottom plate and an upper lid 28, and an introduction passage 24 from the discharge chamber 23 to the cyclone separator 25 is also formed inside the same discharge casing 12. The introduction channel 24 has the same cross-sectional area in the range from the discharge chamber 23 to the cyclone separator 25, and is formed in a straight line or a gentle right turn. The inner cylinder 27 and the upper lid 28 are an integral member and are fastened to the upper part of the cyclone outer wall 26 to be integrated. The upper part of the inner cylinder 27 forms a gas outlet 30 which is an outlet as a compressor.

An oil sump 31 is provided below the cyclone separator 25.
Is formed, and the oil holding amount is defined so that the oil level 32 is within a certain height range. An oil supply passage 33 serving as an oil supply passage is formed from a lower portion of the oil reservoir 31 by a hole formed in the wall surface of the discharge casing 12. The oil supply path 33 is bifurcated at a height higher than the rotation center of the rotors 15 and 16. One of them penetrates the connection surface between the main casing 11 and the discharge casing 12 as a suction side oil supply passage 34 and reaches near the suction side bearing 17. The other reaches the vicinity of the discharge side bearing 18 as a discharge side oil supply passage 35 which is a hole formed inside the discharge casing 12.

According to the embodiment described above, the operation is as follows. First, the motor 14 generates rotational power by electric power supplied from the outside, and when the male rotor 15 having a common shaft is rotationally driven, the female rotor 16 meshed is rotationally transmitted to the male rotor 15, and the compression formed by both rotors and the bore is performed. While feeding the chamber in the axial direction, expand and contract the compression chamber volume,
It sucks, compresses, and discharges the refrigerant gas trapped inside.

Further, the refrigerant gas is supplied to the gas inlet 2 from the outside.
9 to the inside of the screw compressor 1 and the motor 1
After passing through the clearance and outer periphery of No. 4, both rotors 15, 16
Is sucked into the compression chamber from a suction port formed around the lower part of the cylinder. The oil discharged from the suction-side bearing 17 is mixed with the flow of the refrigerant gas before the suction, and the oil discharged from the discharge-side bearing 18 is mixed during the compression process.

After completion of the compression, the refrigerant gas and the oil mixed therein exit from the discharge port and pass through the discharge chamber 23 to the introduction flow path 2.
4 and enters the cyclone separator 25. Inflow channel 24
Is a straight or right-turned shape, no rightward centrifugal force acts on the oil, and it does not actively adhere to the right side surface inside the flow path. Since the introduction flow path 24 is connected to the cyclone outer wall 26 in a tangential direction, the gas that has entered the cyclone separator 25 descends while turning clockwise along the cyclone outer wall 26, and moves downward from the lower end of the inner cylinder 27. Enter the cylinder 27,
The gas is sent out from the gas outlet 30.

In the process of swirling the gas inside the cyclone separator 25, the oil mixed into the gas is more likely to move linearly than the gas due to the effect of the centrifugal force due to the difference in density, and gradually approaches the outer periphery and eventually reaches the outer wall 26 of the cyclone. It adheres to the inner surface and is separated. The oil adhering to the inner surface of the outer wall 26 descends by gravity, flows into the oil sump 31 and is stored.

The discharge pressure of the compressor acts on the oil stored in the oil sump 31, while the vicinity of the bearings 17 and 18 is almost under the suction pressure. Therefore, through the oil supply passages 33, 34, 35 connecting the two positions, the oil is supplied to the bearing 1 by a pressure difference.
7 and 18. The oil enters the compression chamber after being used for lubricating and cooling the bearing, and acts as a lubricant between the screw rotors 15 and 16, a seal between the compression chambers, and a coolant for the heat of compression. Thereafter, the oil is discharged again together with the gas, so that the oil circulates inside the compressor.

In the present embodiment, the cyclone separator 25 is effectively used, the oil separation efficiency is high, and the discharged gas is a flow path swirling inside the cyclone separator 25, so that the axial length is reduced. And compact.

Of the oil mixed in the gas entering the cyclone separator 25, the oil near the outer wall 26 of the cyclone easily adheres to the inner surface of the outer wall by centrifugal force and is easily separated. However, since oil entering from the right end of the introduction flow path 24 requires time until it adheres, the effect of the centrifugal force is reduced due to a decrease in flow velocity or stagnation of the gas flow, and the separation efficiency is deteriorated. In the present embodiment, since the active adhesion of oil to the right side surface is prevented in the process of flowing through the introduction flow path 24, the separation performance of the cyclone separator 25 can be fully utilized.

In this embodiment, since the discharge port 22 to the discharge chamber 23, the introduction flow path 24, and the cyclone separator 25 are integrated into the cast iron discharge casing 12, the vibration noise due to the discharge pulsation is reduced. You can also.
Discharge pulsation originating from the discharge port propagates downstream along the flow of gas, but any of the flow path constituent members
It is surrounded by a thick cast iron wall having a large vibration damping coefficient, and its propagation to the surface is suppressed even when the internal pressure changes.
In addition, the discharge casing 12
Since the surface area can be reduced, the total amount of noise emitted from the surface is also suppressed.

Further, by integrating each element on the discharge side into the discharge casing 12, the manufacturing and disassembly and assembly are simplified, and each flow path is constituted by a hole formed in the casing wall, so that the outer piping is formed. Classes can be omitted.

Further, in the present embodiment, all of the discharge gas and oil sump which are relatively high in temperature are discharged from the discharge casing 1.
2, the heat transfer to the gas in the suction process is small, and the performance deterioration due to the heating of the suction air can be prevented. Even for the high-temperature oil reaching the suction side, the heat transfer to the compression chamber during the suction process can be reduced by forming the suction side oil supply passage 34 outside the compression side surface of the bore.

In the embodiment described above, the male rotor 1
5 is driven by the motor 14 provided at one end, and the rotation is transmitted from the male rotor 15 to the female rotor 16, but may be reversed.

Next, another embodiment of the present invention will be described with reference to FIGS. This is a two-stage separation system in which the cyclone separator 25 is used as a primary separation mechanism, and an oil reservoir below the cyclone is a sub-oil reservoir 56. Further, a cylindrical filter 51 made of glass wool, which is a filtration type separating means, is provided so as to extend above the inner cylinder 27, and the upper end surface is closed with another member. The cyclone outer wall 26 also extends upward and forms an outlet chamber 52 surrounding the filter 51, the upper part of which is closed except for the gas outlet 30. The main oil sump 55 is provided at substantially the same height as the sub oil sump 56 and communicates with an oil recovery path 53 extending from the bottom of the outlet chamber 52. The main oil sump 55 and the sub oil sump 56 are separated by a partition wall 54, but the bottoms of both are connected by an oil communication passage 57. Main oil sump 5
5 and the oil surface 59 of the auxiliary oil reservoir 56 are both set to be higher than the oil communication passage 57. It is desirable that the position of the main oil reservoir 55 be located below the discharge-side bearing 18, since the space can be effectively used.

In the cyclone separator, fine oil particles easily get on the gas flow and the separation efficiency is poor. Therefore, by passing the gas having passed through the cyclone separation through the filter 51,
Oil particles can be separated. The separated oil moves along the fiber of the filter 51 and moves downward by gravity while moving in the gas flow, that is, in the outer circumferential direction of the cylinder. In the process, many oil particles are combined by surface tension and fall from the lower end of the filter 51 to the floor of the outlet chamber 52. The oil temporarily accumulated on the floor surface flows down through the recovery path 53 and flows into the main oil sump 58.

The oil supply passage 33 to the bearing and the like is connected to the lower part of the main oil sump 55, and the oil in the sub oil sump 56 also flows into the main oil sump through the communication passage 57 and joins. The internal pressure at the main oil sump oil level 58 is lower than the internal pressure at the sub oil sump oil level 59. Because, in the gas flow which is the main factor for determining the internal pressure, the sub oil sump oil level 59 is on the upstream side of the filter 51 and the main oil sump oil level 58 is communicated with the downstream side of the filter 51. The difference in internal pressure between the oil levels is caused by the passing pressure loss.

Comparing the amount of oil to be separated and recovered, the oil separated by the primary cyclone separator 25 is the majority of the oil separation mechanism of the two stages, and the oil is separated by the secondary filter 51.
Is small. Therefore, the amount of oil flowing through the communication passage 57 from the sub oil reservoir 56 to the main oil reservoir 55 is much larger than the amount of oil flowing through the recovery passage 53, and
7 is larger than the pressure difference between the two ends of the recovery passage 53. It is preferable to set the sectional area, length, and shape of the communication passage 57 so that the passage pressure loss of the communication passage 57 is substantially equal to the difference between the internal pressures at the oil surfaces 58 and 59 of the two oil reservoirs.

As a result, the gas passing pressure loss in the filter 51 becomes substantially equal to the oil passing pressure loss in the communication passage 57, and the oil levels 58 and 59 can be maintained at substantially the same height.

According to the present embodiment, since even fine oil particles can be recovered, very high oil separation efficiency can be realized. At the same time, the two oil sumps can be effectively used, and the amount of oil held by the compressor can be increased.

Although the difference between the oil levels 58 and 59 may increase due to the influence of the operation state, the pressure state, the capacity control, and the like, the oil level 58 extends to the outlet chamber 52 or the oil level 59
As long as it does not rise to the vicinity of the lower end, there is no problem, and the allowable width of the oil level displacement can be relatively large. Therefore, it is desirable to provide the communication passage 57 with a constant flow valve particularly when used for applications where the oil level difference is widened.

In this embodiment, the main oil reservoir 55 and the communication passage 57 are not provided, the oil supply passage 33 is connected to the sub oil reservoir 56, and the downstream end of the recovery passage 53 communicates with the compression chamber in the suction or compression process. It may be. In that case, the structure can be simplified.

Next, still another embodiment of the present invention will be described with reference to FIG. The direction from the discharge end face of the screw rotor to the suction side is all the same as that of the conventional model, and the oil separation chamber is integrated with the discharge casing 68. An oil separation element provided in an internal space 69 serving as an oil separation chamber has a finer filter 61 made of glass wool than the conventional example.
To cover the entire cross section of the oil separation chamber together with the lower partition 62. A communication path 63 is provided below the partition wall 62. The lower part of the oil separation chamber functions as an oil sump, and the rotor side is an upstream oil sump 64 and the gas outlet 30 side is a downstream oil sump 65 with the partition wall 62 as a boundary. Further, the conventional oil sump 66 functions as it is. The downstream oil sump 65 and the conventional oil sump 66 communicate with each other through an oil flow passage 67 having a diameter larger than that of the communication passage 63.

According to the present embodiment, the discharge gas blows out of the discharge chamber 23 through the flow path extending in the depth direction of the drawing and in the direction of collision with the wall surface, and reaches the internal space 69. At this time, part of the oil mixed into the gas adheres to the wall surface by inertia and is separated. Since the size of the filter 61 is small, the pressure loss is large as compared with the conventional oil separation element, and the flow velocity distribution becomes relatively uniform without requiring a wide approach section before and after the filter 61. After passing through the filter 61 and separating the oil particles having a relatively small particle size, the gas is discharged from the outlet 30.

The oil separated by the collision as the primary separation flows into the upstream oil reservoir 64 and the oil separated by passing through the filter 61 as the secondary separation flows into the downstream oil reservoir 65 by gravity. Since the internal pressure of the internal space has a difference before and after the filter by an amount corresponding to the pressure loss of the filter 31, the oil in the upstream oil reservoir 64 flows to the downstream oil reservoir 65 through the communication passage 63 by the differential pressure. Further, the oil flows from the downstream oil sump 65 to the conventional oil sump 66 through the oil flow path 67 and is sent to each bearing.

According to the present embodiment, since the partition wall 62 is provided, the oil level does not blow up due to the gas flow.
Due to the effect of the fineness of the filter 61, the oil separation efficiency is significantly improved. At the same time, the amount of retained oil is determined based on the downstream oil sump 65, so that it is difficult for oil to be taken out due to an abnormal rise in the oil level. Furthermore, the oil separation efficiency can be improved while shortening the overall length of the screw compressor only by replacing the oil discharge chamber with the discharge casing of the conventional model. Therefore, there are few design changes, and it is easy to improve. In addition, it is possible to convert a running machine to this specification. Even when the compressor is stopped, only the oil levels of the oil sumps 64 and 65 coincide with each other, and there is no fear that an abnormal oil level rise occurs.

Next, still another embodiment of the present invention will be described with reference to FIG. The flow path from the discharge chamber 23 continues to the discharge pipe 74 in the depth direction in the figure, and the discharge pipe 74 passes through the filter 71. The cross section of the oil separation chamber 77 is
And the partition 72 are closed together, and a communication path 73 is opened below the partition 72. The right side in the drawing is the upstream oil reservoir 75 and the left side is the downstream oil reservoir 76 with the partition wall 72 as a boundary.

In this embodiment, since the gas outlet 78 is located upward, there is no need to extend the pipe in the longitudinal direction of the compressor, which is advantageous when the length of the compressor mounting space is limited. . Further, the oil passage 67 becomes unnecessary, and the lower structure can be simplified.

[0047]

According to the present invention, the separation efficiency of the oil separation mechanism can be improved, and the amount of oil taken out of the compressor mixed in the refrigerant gas can be reduced, so that the heat exchanger constituting the refrigerant cycle can be achieved. The performance of the compressor can be improved, and the amount of oil retained inside the compressor can be secured to increase the reliability of the compressor. Further, since the oil separation mechanism can be downsized by improving the separation efficiency, the whole screw compressor can be downsized.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a screw compressor according to an embodiment of the present invention.

FIG. 2 is a system diagram of a refrigerant cycle.

FIG. 3 is a cross-sectional view of the screw compressor according to the embodiment of FIG.

FIG. 4 is a longitudinal sectional view of a screw compressor according to another embodiment of the present invention.

FIG. 5 is a cross-sectional view of the screw compressor according to the embodiment of FIG.

FIG. 6 is a longitudinal sectional view of the vicinity of a discharge section of a screw compressor according to still another embodiment of the present invention.

FIG. 7 is a cross-sectional view of the vicinity of a discharge section of a screw compressor according to still another embodiment of the present invention.

[Explanation of symbols]

11: Main casing, 12: Discharge casing, 13:
Suction casing, 14 ... motor, 15 ... male rotor (screw rotor), 16 ... female rotor (screw rotor), 17 ... suction side bearing, 18 ... discharge side bearing, 21 ... radial discharge port, 22 ... axial discharge port , 23 ... discharge chamber, 24 ... introduction flow path, 25 ... cyclone (cyclone separator), 26 ... cyclone outer wall, 27 ... inner cylinder, 28 ...
Upper lid, 29 ... gas inlet, 30 ... gas outlet, 31 ...
Oil sump, 32 ... Oil level, 33 ... Oil supply path, 34 ... Suction side oil supply path, 35 ... Discharge side oil supply path, 51 ... Filter, 53 ... Oil recovery path, 54 ... Partition wall, 55 ... Main oil sump, 56 ... Secondary Oil reservoir, 57 ... oil communication passage.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigekazu Nozawa 390 Muramatsu, Shimizu-shi, Shizuoka Prefecture Hitachi Air Conditioning Systems Shimizu Production Headquarters (72) Inventor Masayuki Urasin 390 Muramatsu, Shimizu-shi, Shizuoka Prefecture System Shimizu Production Headquarters (72) Inventor Takeshi Hida 390 Muramatsu, Shimizu-shi, Shizuoka Prefecture Hitachi Air Conditioning Systems Shimizu Production Headquarters F-term (reference) 3H029 AA03 AA15 AA21 AB03 BB03 BB37 CC18 CC26 CC45

Claims (8)

[Claims] A screw rotor, a shaft supporting means for rotatably supporting the screw rotor, a casing for accommodating them, a discharge casing in which a discharge port of the casing is formed, and a discharge casing provided downstream of the discharge port. An oil separating unit, and a screw compressor having an oil supply passage for supplying oil separated and recovered by the oil separating unit to the shaft support unit, wherein the oil separating unit is formed in the discharge casing and is a cyclone. And a sump formed at a lower portion of the cyclone. 2. The screw compressor according to claim 1, wherein an introduction flow path from the discharge port to the cyclone is formed in the discharge casing. 3. The screw compressor according to claim 1, wherein said oil supply flow path is formed in said discharge casing and extends from a lower portion of said oil reservoir to said bearing means. 4. The screw compressor according to claim 1, wherein said cyclone has a cyclone outer wall and an inner cylinder, and said inner cylinder is provided with a gas outlet. 5. A screw rotor, a shaft supporting means for rotatably supporting the screw rotor, a discharge casing,
A screw compressor comprising: a cyclone formed in the discharge casing; and a filtration oil separating unit provided downstream of the cyclone. 6. The screw compressor according to claim 5, wherein an oil recovery flow path separated by said filtration type separation means is formed inside said discharge casing. 7. A screw compressor having a screw rotor, a casing for rotatably supporting and housing the screw rotor, a screw compressor element having a discharge port in the casing, and an oil separating means downstream of the discharge port. In the discharge casing formed in the discharge casing, a primary separation means utilizing the density difference and inertia of the gas to be compressed and oil such as a cyclone method or a collision method, and the oil separation means constituted by a secondary separation means by filtration, A main oil reservoir formed at a lower portion of the primary separation unit; a main oil reservoir separated by a partition wall; a sub oil reservoir formed at a lower portion of the secondary separation unit; A screw compressor comprising an oil reservoir and an oil communication passage communicating with a lower portion. 8. The screw compressor according to claim 7, wherein said primary separation means is a cyclone.