JP3994220B2 - Screw compressor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a screw compressor, and is particularly suitable for a refrigerant screw compressor used for refrigerating and air-conditioning that is small in size, high in performance, and less oil is taken out.
[0002]
[Prior art]
In a refrigerant screw compressor used for refrigeration and air conditioning, an oil separation chamber is provided downstream of the discharge port, the oil is separated from refrigerant gas in the oil separation chamber, and the separated oil is separated by gravity into the oil reservoir in the lower part of the oil separation chamber. It is known to drop it, return it to the oil reservoir in the lower part of the main casing in communication, and supply it again to the bearing, for example, as described in JP-A-10-159663.
[0003]
Japanese Patent Application Laid-Open No. 7-243391 discloses a two-stage process using a cyclone and a filtration type (or a collection filter type) in order to achieve high separation efficiency.
[0004]
[Problems to be solved by the invention]
In the above prior art, a coarse mesh must be used as the oil separation element in order to suppress the pressure loss, and sufficient separation efficiency cannot be obtained unless the discharge chamber is enlarged.
[0005]
Further, in the case of using the two-stage oil separation means, there is a possibility that the size of the whole is increased, the vibration portion excited by the pulsation of the discharge pressure is increased, and the generated noise is increased. Furthermore, hot 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 this hot oil is separated from the refrigerant gas in the intake process by one wall surface. Therefore, heat is transferred through the wall surface, and the refrigerant gas is heated, which is a factor in performance degradation.
[0006]
An object of the present invention is to solve the above-mentioned problems of the prior art, increase the efficiency of the oil separation mechanism, and realize a small screw compressor. Another object of the present invention is to improve compressor performance (energy efficiency) and suppress noise generation.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a screw rotor, shaft support means for rotatably supporting the screw rotor, a casing for storing them, a discharge port formed in the casing, and a downstream of the discharge port. In a screw compressor provided with an oil separation means provided and an oil supply passage for supplying oil separated and recovered by the oil separation means to the shaft support means, a space provided downstream of the discharge port. The oil separation means having a discharge chamber, a cyclone outer wall and an inner cylinder and being a cyclone separator, and formed in a range from the discharge chamber to the cyclone separator and connected in a tangential direction to the cyclone outer wall An introduction flow path, an oil sump formed in a lower part of the cyclone separator, an oil supply path that is the oil supply flow path from the oil sump lower part to the shaft support means, Wherein the discharge chamber, the cyclone outer wall, said inlet flow path, said oil sump, the oil supply passage is one that is integrated with the casing is made of cast iron.
[0008]
Furthermore, in the above, it is preferable that the introduction flow path has the same cross-sectional area in the range from the discharge chamber to the cyclone separator and is formed in a straight line or a gentle right turn .
[0015]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIGS.
The refrigerant cycle is configured in the order of the compressor 1, the condenser 2, the expansion valve 3, and the evaporator 4, and forms a circulation path (cycle). Since the compressor 1 plays a role of compressing and sending out the refrigerant gas therein, it is desired that the energy efficiency (performance) which is a gas compression work with respect to the input energy is high.
[0016]
Oil used for lubricating the inside of the compressor is not necessary in the refrigerant cycle, and if it is mixed in a large amount in the refrigerant gas, heat exchange is hindered in the condenser 2 and the evaporator 4. In addition, if a large amount of oil comes out in the refrigerant cycle, the amount of oil held in the compressor decreases, and it becomes difficult to lubricate the compressor itself. Therefore, it is necessary to separate the oil from the refrigerant gas before leaving the compressor.
[0017]
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 in order to facilitate disassembly and assembly. The suction casing 13 is provided with a gas introduction port 29 for introducing refrigerant gas from the outside to the compressor body.
[0018]
The main casing 11 incorporates a motor 14 and a pair of screw rotors (male rotor 15 and female rotor 16). The tooth spaces of the rotors 15 and 16 mesh with each other, the bore wall formed in the main casing 11, and the suction side. The compression chamber is formed by being surrounded by the end face and the discharge side end face formed in the discharge casing 12. The rotor of the motor 14 is fixed to a portion where the shaft of the male rotor 15 is extended. Both rotors 15 and 16 are supported by a suction side bearing 17 held in the main casing 11 and a discharge side bearing 18 held in the discharge casing 12.
[0019]
A slide valve 19 is provided above the rotors 15 and 16 in the main casing 11, and the slide valve 19 is moved by hydraulic pressure acting on the 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, which serve as a communication path to the discharge flow path of the compression chamber that has been compressed. 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 and to connect both discharge ports having a complicated shape and a simple flow path.
[0020]
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 flow path 24 from the discharge chamber 23 to the cyclone separator 25 is also formed inside the same discharge casing 12. The introduction flow path 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 integral members, and are fastened and integrated with the upper part of the cyclone outer wall 26. The upper part of the inner cylinder 27 forms a gas outlet 30 which is an outlet as a compressor.
[0021]
An oil sump 31 is formed in the lower part of the cyclone separator 25, and the oil holding amount is defined so that the oil level 32 is in a certain height range. An oil supply passage 33, which is an oil supply passage, is formed from a lower portion of the oil sump 31 with a hole opened in the wall surface of the discharge casing 12. The oil supply passage 33 is bifurcated at a height equal to or higher than the rotation center of the rotors 15 and 16. One side serves as a suction-side oil supply passage 34 that passes through the coupling surface of the main casing 11 and the discharge casing 12 and reaches the vicinity of 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 in the discharge casing 12.
[0022]
According to the embodiment described above, it operates as follows.
First, the motor 14 generates rotational power by the electric power supplied from the outside. When the male rotor 15 having a common shaft is rotationally driven, the meshed female rotor 16 is transmitted to the male rotor 15 and compressed by both rotors and bores. While feeding the chamber in the axial direction, the volume of the compression chamber is enlarged and reduced, and the refrigerant gas confined in the chamber is sucked, compressed and discharged.
[0023]
Further, the refrigerant gas passes from the outside through the gas inlet 29 and enters the screw compressor 1, passes through the clearance and the outer periphery of the motor 14, and then is compressed from the suction port formed around the lower portions of the rotors 15 and 16. Inhaled into the room. The oil discharged from the suction side bearing 17 is mixed before the suction of the refrigerant gas flow, and the oil discharged from the discharge side bearing 18 is mixed during the compression process.
[0024]
After the compression is completed, the refrigerant gas and the oil mixed therein exit from the discharge port, flow through the introduction passage 24 via the discharge chamber 23, and enter the cyclone separator 25. Since the introduction channel 24 is a straight line or a right-turn shape, the rightward centrifugal force does not act on the oil and does not actively adhere to the right side surface inside the channel. Since the introduction flow path 24 is tangentially connected to the cyclone outer wall 26, the gas that has entered the cyclone separator 25 descends while turning clockwise along the cyclone outer wall 26, and reaches the inner cylinder 27 from the lower end of the inner cylinder 27. It enters the cylinder 27 and is sent out from the gas outlet 30 to the outside.
[0025]
In the process in which the gas swirls inside the cyclone separator 25, the oil mixed in the gas is more likely to move linearly than the gas due to the centrifugal force due to the difference in density, and gradually approaches the outer periphery and gradually adheres to the inner surface of the cyclone outer wall 26. And separated. The oil adhering to the inner surface of the outer wall 26 descends due to gravity and flows into the oil sump 31 to be stored.
[0026]
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, the oil is supplied to the bearings 17 and 18 by the pressure difference through the oil supply passages 33, 34, and 35 connecting both positions. The oil enters the compression chamber after being used for lubrication cooling of the bearing, and acts as a lubricant against the lubrication between the screw rotors 15 and 16, the seal between the compression chambers, and the compression heat. Thereafter, the oil is again discharged together with the gas, so that the oil circulates inside the compressor.
[0027]
In the present embodiment, the cyclone separator 25 is effectively utilized, the oil separation efficiency is good, and the discharge gas becomes a flow path that swirls inside the cyclone separator 25, so that the axial length is reduced to be compact. Can be.
[0028]
Of the oil mixed in the gas entering the cyclone separator 25, the oil close to the cyclone outer wall 26 adheres quickly to the inner surface of the outer wall due to the action of centrifugal force and is easily separated. However, since the oil entering from the right end of the introduction flow path 24 takes time to adhere, the action of centrifugal force is reduced due to a decrease in flow velocity or gas flow stagnation, and the separation efficiency is deteriorated. In the present embodiment, since the oil is prevented from actively adhering to the right side surface in the process of flowing through the introduction flow path 24, the separation performance of the cyclone separator 25 can be fully utilized.
[0029]
In this embodiment, since the discharge port 22, the discharge chamber 23, the introduction flow path 24, and the cyclone separator 25 are integrated in the integrated cast iron discharge casing 12, vibration noise due to discharge pulsation can be reduced. it can. Discharge pulsation originating from the discharge port propagates downstream along the gas flow, but all of the flow path components are surrounded by a thick cast iron wall with a large vibration damping coefficient. Propagation to the surface is suppressed even when the pressure changes. In addition, since the surface area of the discharge casing 12 can be reduced as compared with the conventional discharge chamber, the total amount of noise generated from the surface is also suppressed.
[0030]
Furthermore, by integrating each element on the discharge side into the discharge casing 12, manufacturing and disassembly are simplified, and each flow path is configured by a hole opened in the casing wall surface, so that external piping is omitted. can do.
[0031]
Further, in the present embodiment, all of the discharge gas and oil sump that are at a relatively high temperature are built in the discharge casing 12, so that heat transfer to the gas in the intake process is small and performance deterioration due to intake air heating is prevented. it can. By forming the suction side oil supply passage 34 outside the compression side surface of the bore, heat transfer to the compression chamber during the suction process can be reduced.
[0032]
In the embodiment described above, the motor 14 provided at one end of the male rotor 15 is driven to transmit the rotation from the male rotor 15 to the female rotor 16, but this may be reversed.
[0033]
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 a primary separation mechanism, and an oil sump at the lower part of the cyclone is an auxiliary oil sump 56. Further, a cylindrical glass wool filter 51 which is a filtration type separating means is provided so as to extend on the inner cylinder 27, and the upper end surface is closed with another member. The cyclone outer wall 26 also extends upward to form an outlet chamber 52 that surrounds the filter 51, and its upper portion 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 that continues 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. Both the oil level 58 of the main oil sump 55 and the oil level 59 of the sub oil sump 56 are set to be above the oil communication passage 57. If the position of the main oil reservoir 55 is set below the discharge-side bearing 18, it is desirable because the space can be effectively used.
[0034]
In the cyclone separator, fine oil particles are easy to get on the gas flow and the separation efficiency is poor. Therefore, by passing the gas that has undergone cyclone separation through the filter 51, it is possible to separate even fine oil particles. The separated oil travels down the fibers of the filter 51 and moves downward due to 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 surface 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.
[0035]
The oil supply passage 33 to the bearing or the like is connected to the lower portion of the main oil reservoir 55, and the oil in the auxiliary oil reservoir 56 also flows into the main oil reservoir through the communication passage 57 and joins. The internal pressure at the main oil sump oil surface 58 is lower than the internal pressure at the sub oil sump oil surface 59. This is because, in the gas flow that is the main factor that determines the internal pressure, the secondary oil sump oil surface 59 is on the upstream side of the filter 51, and the main oil sump oil surface 58 is in communication with the downstream side of the filter 51. The difference in internal pressure between the oil levels is caused by the passage pressure loss.
[0036]
Compared with the amount of oil to be separated and recovered, in the two-stage oil separation mechanism, the oil separated by the primary cyclone separator 25 is mostly, and the amount separated by the secondary filter 51 is small. . Therefore, the amount of oil flowing through the communication passage 57 from the auxiliary oil reservoir 56 toward the main oil sump 55 is much larger than the amount of oil flowing through the recovery passage 53, and the pressure loss of oil passing through the communication passage 57 is at both ends of the recovery passage 53. Larger than the pressure difference. It is preferable to set the cross-sectional area or the 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 in internal pressure between the oil levels 58 and 59 of both oil reservoirs.
[0037]
Accordingly, the gas passage pressure loss in the filter 51 and the oil passage pressure loss in the communication passage 57 are substantially equal, and the oil surfaces 58 and 59 can be maintained at substantially the same height.
[0038]
According to the present embodiment, even fine oil particles can be recovered, so that very high oil separation efficiency can be realized. At the same time, two oil reservoirs can be used effectively, and the amount of oil retained in the compressor can be increased.
[0039]
Although the difference between the oil levels 58 and 59 may increase due to the influence of the operating state, the pressure state, the capacity control, etc., the oil level 58 rises to the outlet chamber 52 or the oil level 59 rises to near the lower end of the inner cylinder 27. Unless this is the case, there is no problem and the allowable width of the oil level displacement can be made relatively large. Therefore, it is desirable to provide a constant flow valve in the communication passage 57 particularly when used for applications where the oil level difference is widened.
[0040]
In the present embodiment, the main oil sump 55 and the communication passage 57 are not provided, the oil supply passage 33 is connected to the sub oil sump 56, and the downstream end of the recovery passage 53 communicates with the compression chamber in the suction or compression process. . In that case, the structure can be simplified.
[0041]
Next, still another embodiment of the present invention will be described with reference to FIG.
The direction from the discharge end surface of the screw rotor to the suction side is the same as that of the conventional model, and the oil separation chamber is integrated with the discharge casing 68. The oil separation element provided in the internal space 69 as an oil separation chamber uses a finer glass wool filter 61 than the conventional example, and covers the entire cross section of the oil separation chamber together with the lower partition wall 62. A communication path 63 is provided below the partition wall 62. The lower part of the oil separation chamber functions as an oil reservoir, and the rotor side is an upstream oil reservoir 64 and the gas outlet 30 side is a downstream oil reservoir 65 with the partition wall 62 as a boundary. The conventional oil sump 66 functions as it is. The downstream oil reservoir 65 and the conventional oil reservoir 66 are communicated with each other through an oil passage 67 having a diameter larger than that of the communication passage 63.
[0042]
According to the present embodiment, the discharge gas blows out from the discharge chamber 23 in the direction of colliding with the wall surface through the flow path continuous in the depth direction of the drawing and reaches the internal space 69. At this time, part of the oil mixed in the gas adheres to the wall surface due to inertia and is separated. Since the filter 61 has a fine mesh, the pressure loss is larger than that of 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 oil particles having a relatively small particle diameter, the gas is sent out from the outlet 30.
[0043]
The oil separated by the collision that is the primary separation flows into the upstream oil reservoir 64, and the oil separated by the passage of the filter 61 that is the secondary separation flows into the downstream oil reservoir 65 by gravity. Since the internal pressure in the internal space is different between before and after the filter by the pressure loss of the filter 31, the oil in the upstream oil reservoir 64 flows through the communication path 63 to the downstream oil reservoir 65 with the differential pressure. Further, the oil flows from the downstream oil reservoir 65 to the conventional oil reservoir 66 through the oil passage 67 and is sent to each bearing.
[0044]
According to the present embodiment, since there is the partition wall 62, the phenomenon of the oil surface blowing up due to the gas flow does not occur, the fineness of the filter 61 is also obtained, and the oil separation efficiency is remarkably 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 exchanging the conventional model discharge casing and oil separation chamber. As a result, design changes are few and improvement is easy, and it is also possible to modify the operating machine to this specification. Even when the compressor is stopped, the oil levels of the oil reservoirs 64 and 65 coincide with each other, and there is no fear of an abnormal oil level rise.
[0045]
Next, still another embodiment of the present invention will be described with reference to FIG.
The flow path from the discharge chamber 23 is connected to the discharge pipe 74 in the back direction in the figure, and the discharge pipe 74 penetrates the filter 71. The cross section of the oil separation chamber 77 is closed together with the filter 73 and the partition wall 72, and a communication path 73 is opened below the partition wall 72. The right side in the figure is an upstream oil sump 75 and the left side is a downstream oil sump 76 with the partition wall 72 as a boundary.
[0046]
In the present embodiment, since the gas outlet 78 is on the upper side, it is not necessary to extend the pipe in the longitudinal direction of the compressor, which is advantageous when the length of the compressor mounting place is limited. Further, the oil passage 67 is not required, and the lower structure can be simplified.
[0047]
【The invention's effect】
According to the present invention, the separation efficiency of the oil separation mechanism can be improved, and the performance of the heat exchanger constituting the refrigerant cycle is increased by reducing the amount of oil taken out from the compressor mixed in the refrigerant gas. At the same time, the amount of oil held inside the compressor can be secured and the reliability of the compressor can be improved. Moreover, since the oil separation mechanism can be reduced in size by improving the separation efficiency, the entire screw compressor can be reduced in size.
[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.
3 is a cross-sectional view of the screw compressor according to the embodiment of FIG.
[Fig. 4]
The longitudinal cross-sectional view of the screw compressor in other embodiment by this 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 portion 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 portion of a screw compressor according to still another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION 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 DESCRIPTION OF SYMBOLS ... Radial direction discharge port, 22 ... Axial direction 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 port, 30 ... Gas outlet port, 31 ... Oil reservoir, 32 ... Oil surface, 33 ... Oil supply passage, 34 ... Suction side oil supply passage, 35 ... Discharge side oil supply passage, 51 ... Filter, 53 ... Oil recovery passage, 54 ... partition wall, 55 ... main oil sump, 56 ... sub oil sump, 57 ... oil communication passage.

Claims (2)

Screw rotor, shaft support means for rotatably supporting the screw rotor, casing for housing them, discharge port formed in the casing , oil separation means provided downstream of the discharge port, and oil separation In a screw compressor provided with an oil supply channel for supplying oil separated and recovered by the means to the shaft support means,
A discharge chamber which is a space provided downstream of the discharge port;
The oil separation means having a cyclone outer wall and an inner cylinder as a cyclone separator;
An introduction flow path formed in a range from the discharge chamber to the cyclone separator and connected in a tangential direction to the cyclone outer wall;
An oil sump formed at the bottom of the cyclone separator;
An oil supply passage which is the oil supply passage and extends from the lower part of the oil reservoir to the shaft support means;
A screw compressor characterized in that the discharge chamber, the cyclone outer wall, the introduction flow path, the oil sump, and the oil supply path are integrated with the casing made of cast iron . 2. The screw compressor according to claim 1, wherein the introduction flow path has the same cross-sectional area in a range from the discharge chamber to the cyclone separator, and is formed in a straight line or a gentle right turn .

Images