JP3456090B2 - Oil-cooled screw compressor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil-cooled compressor, and more particularly to an oil-cooled screw compressor that does not require drain water draining work in a receiver tank.

[0002]

In the conventional oil-cooled screw compressor, the outside air introduced through the suction passage is compressed by the rotation of a pair of male and female screw rotors provided in the cylinder, and compressed air is compressed in the cylinder. From the discharge port, it becomes a mixed fluid of high-temperature compressed gas and oil and is pumped into the receiver tank. After that, the large oil drops flow down and accumulate in the oil reservoir below the receiver tank due to the difference in specific gravity. On the other hand, the mixed gas of mist-like compressed air and oil is separated into compressed gas and oil by an oil separator provided in the receiver tank, and the purified compressed air is sent out from the supply port to the consumer side. Further, the oil stored in the oil reservoir below the receiver tank is cooled and lubricated in the compression working space by the compressed air pressure in the tank, and the bearing between the screw rotor and the cylinder and the shaft and shaft supporting the screw rotor shaft are supported. Supplied for lubrication of sealing devices.

In such an oil-cooled compressor, the outside air is introduced, compressed and temporarily stored in the receiver tank and then supplied to the consumer side, but the consumption of compressed air is small. If so, the residence time of the compressed air in the receiver tank becomes longer, and therefore the temperature of the compressed air also drops during this time, so that the moisture in the air condenses in the receiver tank and becomes drain water, and the oil reservoir in the receiver tank accumulates. Collect at the bottom. When the drain water accumulates, it mixes with the oil, causing deterioration of the properties of the oil and an emulsification phenomenon. As a result, a mixed liquid of deteriorated or emulsified oil and drain water is sent to the inside of the cylinder, bearing device, etc., and normal cooling and lubrication operations cannot be performed, causing seizure of sliding parts and There was a problem that rust was generated inside. For this reason,
When starting work every day, the drain water that had collected at the bottom of the oil reservoir of the receiver tank had to be opened and drained one by one.

An oil-cooled compressor disclosed in, for example, Japanese Patent Publication No. 7-117051, is known as a structure that does not require such drainage work. In this conventional oil-cooled compressor,
The mixed fluid of oil and drain water accumulated below the receiver tank is directly applied from the bottom of the receiver tank to the rotor chamber, which is lower than the pressure inside the receiver tank, together with the drain water generated in the header part of the oil separator by using the differential pressure. The drain water draining operation is eliminated by discharging the drain water together with the compressed air heated by the compression heat to the consumer side.

However, this conventional device has the following problems. First, while the lubricating oil introduced into the working space from below the receiver tank cools, lubricates and seals the working space, the drain water and oil are introduced in a mixed state, Especially in an environment where the humidity is high and the amount of air consumed is small and the residence time of compressed air in the receiver tank is long, drain water is often generated, and the water content in the oil increases, which results in poor lubrication of each sliding part. As a result, it is possible to accelerate seizure and abnormal wear. Secondly, since the destination of the oil containing drain water is a position where the pressure in the range from the suction port of the compressor to the compression working space is low, the passage after the destination of the drain water and the working space are A large amount of rust is easily generated, and the temperature rise of the compressed air is not so high because it is in the early stage of compression. Thirdly, when the unloader device is controlled to open and close according to the amount of air consumed on the consuming side, so-called full-load operation and no-load operation are repeated, the unloader device is closed during no-load operation, and intake into the cylinder is performed. Air inflow stops. Therefore, the suction side in the compressor body becomes a negative pressure, and the differential pressure between the receiver tank and the receiver tank further increases, and the amount of lubricating oil containing drain water flowing into the working space also increases. Is inherent in the problem of becoming larger.

In view of the above, the present invention solves the above problems and satisfactorily lubricates the sliding parts of the male and female screw rotors, cylinders, etc., and also collects drain water satisfactorily. The object is to provide a screw compressor.

[0007]

According to a first aspect of the present invention, there is provided an oil-cooled screw compressor, a compressor main body for rotatably housing a pair of male and female screw rotors in a casing, and a suction of the compressor main body. An unloader device for controlling the intake air amount provided in the mouth, a receiver tank provided in communication with the discharge port of the compressor body, and an oil in the compressed air discharged from the compressor body in communication with the receiver tank. In an oil-cooled screw compressor provided with an oil separator for separating the screw rotor, when the seal line of the preceding male and female screw rotor is located at the discharge start position in the cylinder of the casing that houses the screw rotor, The first opening is formed in the vicinity of the suction side of the seal line adjacent to the suction side by the groove width of the rotor, and is further closer to the suction side than the first opening and follows the male and female screw rotors. When the rule line is at the suction closed position, a second opening is formed at a position closer to the discharge side than the seal line adjacent to the discharge side by the groove width of the screw rotor, and the second opening is formed in the second opening. While connecting the first pipe for oil supply that communicates with the position above the oil reservoir bottom of the receiver tank,
A second pipe for collecting drain water communicating with the bottom of the oil reservoir of the receiver tank is joined to a third pipe for collecting oil communicating with the bottom of the oil separator to communicate with the first opening of the casing. Only the clean oil that does not contain drain water is introduced into the second opening that opens into the closed working space that does not communicate with the suction space through the first pipe. After surely forming the oil film on the surface of the rotor and cylinder, take out only the drain water accumulated at the bottom of the oil sump through the second pipe, and collect a small amount of recovered oil from the bottom of the oil separator. Of the drain water is evaporated by the heat of compression of the high-temperature compressed gas immediately before discharge, and is introduced outside the receiver tank together with the compressed air. It is what is discharged.

In the oil-cooled screw compressor according to claim 2 of the present invention, the second opening position provided in the casing is
By drilling with a gap larger than the groove width of the screw rotor from the first opening position, the lubricating oil introduced into the male and female screw rotors and various parts in the cylinder is previously formed by the clean lubricating oil introduced from the second opening. Since the drain water is introduced through the first opening after the reliable formation, it is possible to prevent an adverse effect due to the oil film running out of the sliding portion due to the introduction of the drain water.

In the oil-cooled screw compressor according to claim 3 of the present invention, since the throttle is provided in the middle of the second pipe,
Since only the drain water collected at the bottom of the oil sump is introduced into the first opening and collected, power loss can be minimized.

In the oil-cooled screw compressor according to the fourth aspect of the present invention, by making the inner diameter of the second pipe smaller than the inner diameter of the first pipe, the throttle in the middle of the second pipe can be omitted. .

In the oil-cooled screw compressor according to a fifth aspect of the present invention, a drain water suction preventive member is provided at the oil suction port of the first pipe communicating with the oil sump, so that the drain is sucked from the oil suction port. It is possible to prevent the intake of water and supply only the clean lubricating oil containing no drain water to the working space.

[0012]

DETAILED DESCRIPTION OF THE INVENTION A first embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 1, the oil-cooled compressor body 1 includes a pair of male and female screw rotors 2 and 2A (only the male screw rotor 2 is shown in FIG. 1) that mesh with each other in a cylinder 4 of a casing 3. It is stored in a freely rotatable manner. An intake passage 6 for introducing outside air communicates with an intake port 5 provided on the negative side of the cylinder 4, and an intake filter 7 is provided in the intake passage 6 and An intake block valve 9 as an unloader device for controlling the intake air amount is provided between the intake port 5 and the receiver tank, which will be described later, and closes the intake passage 6 via a regulator 8 when the pressure in the receiver tank becomes higher than a set pressure. There is. On the other hand, the check valve 11 is attached to the discharge port 10 provided below the cylinder 4 in the figure.
A receiver tank 12 communicates with a discharge flow path 11 provided with A. This receiver tank 12 is provided with an oil reservoir 13 at the bottom and an oil separator 14 for oil separation at the top,
A header portion 15 is provided above the oil separator 14, and an opening / closing valve 17 for connecting to the consumer side 16 is connected to the header portion 15. The cylinder 4 is provided with first and second openings 4A and 4B for communicating first and second pipes, which will be described later, and a control channel 18 having one end communicating with the header portion 15 is formed. By communicating the other end with the regulator 8, the internal pressure of the receiver tank 12 is introduced into the regulator 8 to open and close the intake blocking valve 9.

Further, a suction side shaft 19 and a discharge side shaft 20 are provided coaxially with the screw rotor 2 in the male and female paired screw rotors 2 and 2A, respectively. Then, from the inside to the bearing chamber 3A provided on the negative side of the casing 3, the suction side shaft
A bearing 22 and a shaft sealing device 23 that rotatably support the 19 are provided. Further, a belt 27 is hung between a driven pulley 24 provided at the end of the intake side shaft 19 of the male screw rotor 2 and a drive pulley 26 provided on the power shaft of a motor 25, which is a prime mover. The female screw rotor 2A, which is rotationally driven and simultaneously meshes with the male screw rotor 2 to rotate, is rotationally driven. Further, a bearing 29 for rotatably supporting the shaft sealing device 28 and the discharge side shaft 20 is provided from the inside in a bearing chamber 3B provided on the other side of the casing 3.

Further, a first pipe 30 for supplying lubricating oil, one end of which communicates with the oil suction port 30A, is connected to a position above the bottom of the oil sump 13 of the receiver tank 12, and the other end 30B is bored in the cylinder 4. An oil cooler 31 and an oil filter are provided in the middle of the first pipe 30 which communicates with the first opening 4A provided.
32 are provided. Further, a baffle plate 33 serving as a drain water suction preventer is provided at the oil suction port 30A provided above the bottom of the oil sump 13, and a bypass valve that opens and closes according to the oil temperature is provided on the primary side of the oil cooler 31. 34 is provided, and bypass piping provided in parallel with the oil cooler 31 in this bypass valve 34
35 are provided. Also, the oil sump 13 of the receiver tank 12
Second piping for drain water recovery that communicates with one end 36A at the bottom
36 is connected, and the other end 36B communicates with the second opening 4B formed in the cylinder 4, and the second pipe 36 is provided with an oil filter 37 and an orifice 38 as a throttle. In addition, one end 40 is provided in the oil reservoir 39 that is the lower
A third pipe 40 for collecting separated oil, which communicates with A, is connected, and the other end 40B has a throttle 40E, a check valve 40C, and a strainer 40D.
Is connected to the secondary side of the orifice 38 of the second pipe 36, merges with a small amount of separated oil recovered from the oil separator 14, and is connected to the first opening 4A of the cylinder 4. . The inner diameter of the second pipe 36 is smaller than the inner diameter of the first pipe 30. Also, one ends 41A and 42A of the first and second branch pipes 41 and 42 are connected to the secondary side of the oil filter 32 provided in the first pipe 30, respectively, and the other end 41 thereof is also connected.
B and 42B communicate with the bearing chambers 3A and 3B, respectively.

Next, the first opening 4A and the second opening 4
B will be described. FIG. 2 shows the end faces on the suction side of the pair of male and female screw rotors 2 and 2A. The part surrounded by the chain double-dashed line in the drawing is the suction end face 43 of the casing 3. 3 shows a developed view of the inner wall of the cylinder 4, the lower side of the figure shows the suction port 5, the upper side of the figure shows the discharge port 10, and a to f in the figure are the inner wall of the cylinder 4. The positional relationship of the seal line of the male screw rotor 2 is shown, and g ~ l
Indicates the position of the seal line of the female screw rotor 2A. When the male and female screw rotors 2 and 2A rotate while meshing with each other, the seal lines of the male and female screw rotors 2 and 2A move sequentially from the suction side to the discharge side (upward in the figure) to gradually reduce the space volume. The compression action continuously. For convenience of description, the male screw rotor 2 side will be described below, but the female screw rotor 2A side is also substantially symmetrical and has the same space, so detailed description will be omitted. First, when the preceding seal line (hereinafter referred to as the preceding seal line) x is moved from the position of the seal line b to the positions of the seal lines c, d, e, f by the rotation of the male screw rotor 2, the groove width of the male screw rotor 2 is divided. That is, the seal line x'following by one pitch (P) (hereinafter referred to as the trailing seal line) also moves sequentially from the position a to the seal lines b, c, d, e. Similarly, when the female screw rotor 2A rotates, the preceding seal line (hereinafter referred to as the preceding seal line) y is i, j,
When moved to j, k, l, the groove width of the female screw rotor 2A, that is, the seal line y'following one pitch (hereinafter referred to as the trailing seal line) y'is also sequentially h, i, j, k from the seal line g.
Move to position. Formed by the preceding seal lines x, y while the preceding seal lines x, y reach the seal lines b, h which are the intake closing positions and the trailing seal lines x'y 'reach the seal lines a, g. Air is sucked into the groove space. Further, the male and female screw rotors 2 and 2A rotate, and the leading seal lines x and y reach the seal lines c and i and the trailing seal lines x ′ and y ′ reach the seal lines b and h. Inhalation is performed. When the trailing seal lines x ′, y ′ reach the seal lines b, h, that is, when the preceding seal lines x, y reach c, i, the suction of air is completed, and at the same time, the seal lines b, c are reached. , H, i and the working space surrounded by the cylinder 4 initiates the compression. Subsequently, as the male and female paired screw rotors 2 and 2A rotate, the preceding seal lines (x, y) are changed to seal lines (d, j), (e,
k) (f, l) is reached, and at the same time, the trailing seal line (x ', y)
′) Reaches (c, h) (d, j), (f, k),
The volume of the intake air is gradually reduced and the seal lines c, d, i,
j, the working space surrounded by the cylinder 4, the seal line d,
e, j, k and the working space surrounded by the cylinder 4, the seal lines e, f, k, l and the working space surrounded by the cylinder 4 are compressed as they proceed. When the preceding seal lines x and y reach the seal lines f and l which are the discharge start positions (at this time, the subsequent seal lines x'and y'are located at the seal lines e and k), compressed air is discharged from this position. When the discharge is started and the trailing seal lines x ′ and y ′ reach the seal lines f and l, the discharge is completed.

The first opening 4A has a groove width of the male screw rotor 3, that is, one pitch when the preceding seal lines x and y of the male screw rotor 3 are at the seal line f which is the discharge start position. Only (P) is provided near the suction side of the seal line e adjacent to the suction side. On the other hand, the second opening 4B is closer to the suction side than the first opening 4A and is discharged from a suction closing position (sealing line b) closed by the seal line x'following the male screw rotor 3. It is drilled at a position closer to the side. This second opening 4B
It is desirable that the positions of the holes are formed with a gap L which is larger than the groove width of the male screw rotor 3 than the position of the first opening 4A, that is, one pitch or more (L> P). In the case where the is designed to be short, it does not necessarily have to be one pitch or more.

Next, the operation of the above configuration will be described. When the motor 25 is started, the male screw rotor 2 and the female screw rotor 2A rotate while meshing with each other, whereby the outside air passes through the suction filter 7 and flows into the suction passage 6, and then passes through the intake blocking valve 9 in the open state. To the suction port 5, and a compression action is performed by the action space formed by the male and female screw rotors 2 and 2A and the casing 4. At this time, the oil sump 13
Clean oil O containing no drain water D is introduced into the working space from the oil suction port 30A through the first pipe 30 due to the pressure difference between the working space and the cooling / lubrication of the working space. Sealing is performed, and the oil film is surely formed at this stage.
Then, the compressed air and the oil in the gas-liquid mixed state in the working space are discharged to the discharge port 10. The discharged compressed air and oil in the gas-liquid mixed state is sent to the receiver tank through the discharge passage 11.
Pumped to 12. Then, in the receiver tank 12, a large oil droplet is dropped and stored in the oil reservoir 13 below the receiver tank 12 due to the difference in specific gravity. On the other hand, the mist-like mixed gas of compressed air and oil is separated into compressed air and oil by the oil separator 14, and the purified compressed air is sent from the header portion 15 to the consumer side 16. When the temperature of the oil passing through the first pipe 30 is lower than the predetermined temperature, a part or all of the oil is supplied to the working space through the bypass pipe 35 by the bypass valve 34, while the temperature of the oil is kept at the predetermined temperature. When the temperature is higher than the temperature, the oil cooled by the bypass valve 34 through the oil cooler 31 is supplied to the working space. Also,
First and second branch pipes 41 branched from the middle of the first pipe 30
From 42, clean lubricating oil O is supplied to the bearing chambers 3A and 3B accommodating the bearings 22 and 29 and the shaft sealing devices 23 and 28, and the bearings 22 and 29 and the shaft sealing devices 23 and 28 are cooled and lubricated.・ It is designed to be sealed.

Further, the pipe at the outlet of the header portion 15 is connected to the regulator 8 via the control flow path 18, and the intake blocking valve 9 is closed when the pressure in the receiver tank 12 reaches a predetermined pressure. Has become.

Further, the drain water D accumulated at the bottom of the oil sump 13 of the receiver tank 12 is a recovery passage for a minute amount of separated oil O ′ accumulated in the oil sump 39 of the oil separator 14 from the second pipe 36. The other end 40B merges through the third pipe 40 and the compression action space (sealing lines d, e, j, k and the cylinder 4 immediately before discharge together with the drain water D through the first opening 4A). ) Is introduced in. The introduction of the oil O ′ and the drain water D is performed by the pressure inside the receiver tank 12 and the pressure difference between the first opening 4A side. Since it is a working space with a relatively small difference and is located far from the suction working space, it is also a working space less susceptible to the influence of negative pressure during no-load operation. In this way, the drain water D introduced into the compression action space immediately before discharge from the first opening 4A in a mixed state of oil O ′
Is evaporated by the heat of compression of the high-temperature compressed air immediately before discharge, is pumped together with the compressed air into the receiver tank 12 through the discharge flow path 11, passes through the oil separator 14, and is discharged to the outside of the receiver tank 12.

As described above, according to this embodiment, the drain water D accumulated at the bottom of the oil reservoir 13 of the receiver tank 13 is compressed in the compression action space in the compressor body 1 immediately before being discharged, by the compression of the high temperature compressed air. Ejection flow path 11, which evaporates due to heat and compressed air,
Receiver tank 12, receiver tank via oil separator 14
Drain water is not discharged to the oil sump 13 because it is discharged to the outside.

Further, regarding the positional relationship of the first opening 4A in the cylinder 4, the male screw rotor 2 is described.
When the preceding seal line x is located on the seal line f, which is the discharge start position, the suction side on the seal line e adjacent to the suction side by the groove width of the male screw rotor 2, that is, one rotor groove pitch (P). It has been drilled most recently. This position does not communicate with the discharge port 10 and is farthest from the suction action space,
Rather, since it is a closed space close to the pressure on the receiver tank 12 side, it is the working space in which the pressure fluctuation is the smallest even when the compressor repeatedly repeats full load and no load depending on the fluctuation of the air consumption. Therefore, since the flow rate fluctuations of the drain water D introduced by the pressure difference between the inside of the receiver tank 12 and the separated oil O ′ introduced from the oil separator 14 are small, the suction action space at the time of no load operation as in the conventional structure. A large amount of drain water D and oil O'will not be introduced due to the negative pressure inside, and a large power loss will not occur. Furthermore, since the drain water D is introduced into the compression action space immediately before discharge, dust and sludge mixed in the drain water D is immediately discharged from the discharge port 10,
It is possible to prevent an accident in which the male and female screw rotors 2 and 2A and the cylinder 4 are bitten and damaged, and the male and female screw rotors 2 and 2A and the cylinder 4 are not worn. Further, since the drain water D is introduced into the working space immediately before the discharge in the high temperature and high pressure state, the drain water D can be surely evaporated. Moreover, since the drain water D is introduced into the compression working space by the third pipe 40 in a mixed state with the oil O ′ in the oil reservoir 39, the male and female screw rotors 2, 2 forming the working space are described.
It is possible to always collect only a fixed amount of drain water D without lowering the lubricity of A and the cylinder 4.

Further, clean oil O is supplied from the oil suction port 30A of the oil reservoir 13 through the first pipe 30 to the compression space surrounded by the seal lines c, d, i and j from the second opening 4B. Since it is introduced, cooling, lubrication, and sealing of the male and female screw rotors 2 and 2A and the cylinder 4 can be reliably performed. Further, since the oil O is introduced into the compression working space after the suction process is completed, the compressed air contained in the oil re-expands in the suction port 5 to reduce the intake air amount of the compressor. It does not reduce performance or cause power loss. Further, since the oil O is introduced into the working space before the drain water D is introduced into the compression working space, an oil film can be formed in advance on the surfaces of the screw rotors 2 and 2A and the cylinder 4, and good lubrication can be performed. At the same time, the occurrence of rust due to the drain water D and the seizure due to insufficient lubrication can be eliminated. Further, clean oil O is introduced into the bearing chambers 3A, 3B via the first and second branch pipes 41, 42 branched from the first pipe 30, so that the bearings 22, 29 and the shaft sealing devices 23, 28 are burned. Can be prevented from sticking, and the shaft sealing device 23,
The gas can be sealed by 28.

Further, by providing an orifice 38 which is a throttle in the middle of the second pipe 36, the receiver tank 12
Since it is possible to give resistance to the drain water D that is pressure-fed from the bottom of the oil sump 13 and limit the discharge amount corresponding to the generated amount, only the drain water D is deposited and high temperature is generated in the compression action space immediately before discharge. The compressed air can be efficiently evaporated and discharged to the outside of the receiver tank 12.

Further, by making the inner diameter of the second pipe 36 smaller than the inner diameter of the first pipe 30, the orifice 38 can be omitted, and the drain which is pressure-fed from the bottom of the oil reservoir 13 of the receiver tank 12. The passage section of the water D can be made small, and only the drain water D can be introduced into the compression action space immediately before discharge, and the entire amount can be efficiently evaporated in the action space.

Moreover, since the oil suction port 30A of the first pipe 30 communicating with the oil reservoir 13 is provided with the baffle plate 33, the clean oil O is not mixed with the drain water D from the oil suction port 30A.
Only the second opening 4B can be introduced into the bearing chambers 3A and 3B.

The present invention is not limited to the above-described embodiment. For example, in the embodiment, the first and second openings are provided in the cylinder on the male screw rotor side, but they are provided in the cylinder on the female screw rotor side. Also, various modifications are possible such as being applicable to the high-pressure stage side of a multi-stage compressor other than the one-stage compressor as in the embodiment with the same structure.

[0027]

The oil-cooled screw compressor according to the first aspect of the present invention is provided with a compressor main body which rotatably accommodates a pair of male and female screw rotors in a casing, and an intake port of the compressor main body. An unloader device for controlling the intake air amount, a receiver tank provided in communication with the discharge port of the compressor body, and oil that communicates with the receiver tank and separates the oil in the compressed air discharged from the compressor body. In an oil-cooled screw compressor provided with a separator, when the seal line of the preceding male and female screw rotor is in the discharge start position in the cylinder of the casing that houses the screw rotor, the groove width of the screw rotor is While the first opening is bored in the vicinity of the suction side of the seal line adjacent to the suction side only, the seal line that is closer to the suction side than the first opening and that follows the male and female screw rotor is sucked. When in the retracted position, a second opening is formed at a position closer to the discharge side than the seal line adjacent to the discharge side by the groove width of the screw rotor, and the oil reservoir of the receiver tank is provided at the second opening. While connecting the first pipe for oil supply that communicates with the position above the bottom part, the second pipe for collecting drain water that communicates with the oil reservoir bottom part of the receiver tank,
The drain water collected at the bottom of the oil reservoir of the receiver tank is collected as drain water by joining the third pipe for oil recovery communicating with the bottom of the oil separator and communicating with the first opening of the casing. The drain water is drained to the outside of the receiver tank through the second pipe for use through the first opening into the compression action space of the compressor body and evaporates due to the compression heat of the hot compressed air and discharges it out of the receiver tank together with the compressed air. Can be eliminated. Further, since the position of the first opening is not communicated with the discharge port as described above and is communicated with the compression action space located far from the suction action space, the pressure difference between the inside of the receiver tank is small. Since the drain water or the separated oil introduced from the oil separator is introduced into the working space, the flow rate fluctuation is small, and since a fixed amount of the drain water is always introduced, there is no power loss due to this. In addition, since the drain water is introduced into the working space immediately before discharge, dust and sludge mixed in the drain water is immediately discharged from the discharge port, so that it is possible to prevent accidents and wear due to the trapping of dust and sludge, and to prevent drainage. Since the water is introduced into the compression action space immediately before the discharge in the high temperature and high pressure state, the drain water is effectively evaporated. Moreover, since the drain water is introduced into the compression action space by the third pipe in a mixed state with the separated oil in the oil sump, the lubricity of the screw rotor and the cylinder forming the compression action space is not deteriorated. Furthermore, by providing the second opening at the position of the compression action space after the suction process is completed as described above, only clean oil is introduced into the compression action space from the oil reservoir through the first pipe. The cooling, lubrication, and sealing of the screw rotor and cylinder can be reliably performed, and the compressed air contained in the supplied clean oil expands in the intake port, reducing the amount of intake air taken into the compressor. I won't let you. In addition, since only clean oil containing no drain water is introduced into the compression working space, a uniform oil film can be formed on the surface of the screw rotor and cylinder, good lubrication can be performed, and rust caused by drain water can be achieved. There is no seizure due to the occurrence of defects or poor lubrication.

According to a second aspect of the present invention, in the oil-cooled screw compressor, the second opening position provided in the casing is opened at a distance larger than the groove width of the screw rotor from the first opening position. By installing, clean oil is introduced into the compression action space before the introduction of drain water in the compression action space,
An oil film can be surely formed in advance before the drain water is introduced to the surfaces of the screw rotor and the cylinder, and as a result, the screw rotor and the cylinder can be lubricated more favorably.

In the oil-cooled screw compressor according to the third aspect of the present invention, by providing the throttle in the middle of the second pipe, resistance is given to the drain water pressure-fed from the oil reservoir bottom of the receiver tank. It is possible to limit the discharge amount corresponding to the generated amount, deposit only drain water, and evaporate it efficiently by the high temperature compressed air immediately before discharge.

In the oil-cooled screw compressor according to claim 4 of the present invention, by making the inner diameter of the second pipe smaller than the inner diameter of the first pipe, the cross section of the passage of the drain water is reduced, Only the drain water can be completely evaporated in the compression action space without providing an orifice or the like.

In the oil-cooled screw compressor according to claim 5 of the present invention, a drain water suction preventive member is provided at the oil suction port of the first pipe communicating with the oil sump, whereby drain water and dust, Only clean oil that is not mixed with sludge can be introduced into the compression space.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view of an inlet side showing an embodiment of the present invention.

FIG. 3 is a development view of a cylinder showing an embodiment of the present invention.

[Explanation of symbols]

1 Compressor body 2 Male screw rotor 2A female screw rotor 3 casing 4 cylinders 4A First opening 4B Second opening 5 suction port 6 Unloader device 10 outlet 12 receiver tank 13 oil sump 14 Oil separator 30 First piping 30A oil inlet 33 Baffle plate (drain water suction prevention body) 36 Second piping 38 Orifice 40 Third pipe P groove width x Leading seal line x'The trailing seal line

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-279875 (JP, A) Actual opening Sho 62-78386 (JP, U) Actual opening Sho 59-45284 (JP, U) Actual opening Sho 49- 84711 (JP, U) Japanese Patent Publication 7-117051 (JP, B2) (58) Fields surveyed (Int.Cl. ⁷ , DB name) F04C 29/02 351 F04C 29/02 F04C 29/02 311 F04C 29 / 02 341 F04C 18/16

Claims (5)

(57) [Claims] 1. A compressor body for rotatably housing a pair of male and female screw rotors in a casing, and an unloader device for controlling an intake air amount provided at an intake port of the compressor body.
An oil-cooled screw provided with a receiver tank provided in communication with the discharge port of the compressor body, and an oil separator connected with the receiver tank and separating oil in compressed air discharged from the compressor body. In the compressor, when the seal line of the preceding male and female screw rotors is located at the discharge start position in the cylinder of the casing that houses the screw rotor, the seal line adjacent to the suction side by the groove width of the screw rotor is sucked. While the first opening is formed in the vicinity of the side, the screw rotor is further closer to the suction side than the first opening, and the seal line following the male and female screw rotor is at the suction closed position. A second opening is formed at a position closer to the discharge side than the seal line adjacent to the discharge side by the groove width of the above, and an oil supply communicating with a position above the oil reservoir bottom of the receiver tank is provided in the second opening. For While connecting the one pipe, the second pipe for collecting drain water, which communicates with the bottom of the oil reservoir of the receiver tank, is joined with the third pipe for collecting oil, which communicates with the bottom of the oil separator. An oil-cooled screw compressor characterized by being communicated with a first opening of a casing. 2. The second opening position provided in the casing is bored at a distance larger than the groove width of the screw rotor from the first opening position. Oil-cooled screw compressor. 3. The oil-cooled screw compressor according to claim 1, wherein a throttle is provided in the middle of the second pipe. 4. The inner diameter of the second pipe is smaller than the inner diameter of the first pipe.
The oil-cooled screw compressor described. 5. The oil-cooled screw compressor according to claim 1, wherein a drain water suction preventive member is provided at an oil suction port of the first pipe communicating with the oil reservoir.