JPH061790U - Oil-free screw compressor - Google Patents

Abstract

(57) [Abstract] [Purpose] Prevents oil leakage from the atmosphere communication hole to the outside of the machine without deteriorating the performance of the shaft seal part, and recovers the lubricating oil in the oil tank below the speed increasing device from the shaft seal part. An oil-free screw compressor that enables the above is provided. [Structure] The inner peripheral surface of a shaft sealing portion 32 including a labyrinth seal provided around the input shaft 33 of the speed increasing device 13 is communicated with the outside of the speed increasing device 13 on the driving portion side, and toward the driving portion side, An oil return hole 1 forming an acute angle with respect to the input shaft 33, a pipe 2 for communicating the oil return hole 1 with the second atmosphere communication hole 24, and an intermediate portion of the pipe 2 at a position higher than the intermediate portion. And a pressure equalizing hole 3 communicating with the atmosphere is provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an oil-free screw compressor in which compressor bodies are arranged in a single stage or multiple stages.

[0002]

[Prior art]

 Conventionally, the oil-free screw compressor shown in FIGS. 2 to 5 is known. This compressor is provided with a first-stage compressor body 11 and a second-stage compressor body 12 arranged in two stages, both of which have a casing 14 of a speed increasing device 13 whose lower part is an oil tank. It is fixed to. The first-stage compressor body 11 has a pair of male and female screw rotors F1 and M1 which mesh with each other and are housed in a rotor chamber of a casing C1 with one opening at a suction port S1 and the other at a discharge port D1. Similarly, the stage compressor body 12 has screw rotors F2 and M2 housed in a rotor chamber of a casing C2 that opens to the suction port S2 and the discharge port D2. The screw rotors F1 and M1 are rotatably supported by lubrication bearings 15 and 16 on the shafts on both sides thereof, and a labyrinth seal is included between the bearings 15 and 16 and the screw rotors F1 and M1. The shaft sealing parts 17 and 18 are interposed. Similarly, the screw rotors F2 and M2 are rotatably supported by lubrication type bearing units 19 and 20, and a shaft sealing unit 21 including a labyrinth seal is provided between the bearing units 19 and 20 and the screw rotors F2 and M2. 22 is interposed.

As shown in FIG. 3, the shaft sealing portion 17 of the first-stage compressor body 11 has a first atmosphere communicating hole 23 for communicating the inner peripheral surface of the shaft sealing portion 17 with the atmosphere. A second atmosphere communication hole 24 is provided. In this way, by providing the first atmosphere communication hole 23 and the second atmosphere communication hole 24 to reduce the pressure gradient in the portion from the second atmosphere communication hole 24 to the first atmosphere communication hole 23, the bearing portion The flow of lubricating oil from the 15th side toward the screw rotors F1, M1 side is stopped at the location of the second atmosphere communication hole 24 to allow the lubricating oil to escape to the outside of the machine, and the second atmosphere communication hole. It is formed so that the lubricating oil that has passed through 24 locations and flows out to the side of the first atmosphere communication hole 23 escapes from the first atmosphere communication hole 23 to the outside of the machine. By doing so, it is possible to prevent the lubricating oil from leaking from the bearing portion 15 into the storage space of the screw rotors F1 and M1, that is, the rotor chamber (Japanese Utility Model Publication No. 3-550). Although not shown, similar first air communication holes and second air communication holes are also provided at the shaft seal portion 21 of the second stage compressor body 12.

The screw rotors F1 and M1 can be synchronously rotated by the synchronous gears 25 and 26 attached to the suction side shaft end portions, and similarly, the screw rotors F2 and M2 can be synchronously rotated by the synchronous gears 27 and 28, respectively. There is. Further, the discharge port D1 of the first stage compressor body 11 communicates with the suction port S2 of the second stage compressor body 12. On the other hand, the large gear 34 is attached to the input shaft 33 that penetrates the casing 14 of the speed increasing device 13 via the bearing portion 31 and the shaft sealing portion 32 including the labyrinth seal, and is attached to the discharge side shaft end portions of the screw rotors D1 and D2. The small gears 35 and 36 are meshed with the large gear 34. An end portion of the input shaft 33 protruding from the casing 14 is connected via a coupling 37 to a drive unit (not shown) such as a motor or an output shaft of an engine. The end of the input shaft 33 on the side opposite to the coupling is rotatably supported by a bearing 38, and the side of the shaft opposite to the coupling is connected to the space above the oil tank via the bearing 38. A breather device 40 for releasing the air in the space 39 and the small space 39 to the outside of the machine is provided.

FIG. 4 shows the mutual positional relationship in the vertical plane of the axes of the screw rotors F1, M1, F2, M2 and the input shaft 33. In the figure, O1, O2, O3, O4, and O5 correspond to the axes of the above-mentioned axes in this order, HL indicates a horizontal line and VL indicates a vertical line, and the uppermost part of the input shaft 33 is a screw rotor. The lowermost part of the shafts of F1 and M1 and the lowermost part of the shafts of the screw rotors F2 and M2 are formed so as to be located at a lower position. Then, the screw rotors D1, D2 are driven by the drive unit (not shown) via the coupling 37, the input shaft 33, the large gear 34, and the small gears 35, 36, and the synchronous gears 25, 26, 27, 28 are driven. The screw rotors M1 and M2 are rotated in synchronism with the screw rotors D1 and D2.

The gas sucked into the rotor chamber of the first-stage compressor body 11 through the suction port S1 as the rotor rotates is compressed in an oil-free state, is discharged through the discharge port D1, and is discharged through the suction port S2. It is sucked into the rotor chamber of the second stage compressor body 12. Then, the gas is further compressed by the main body of the second stage compressor 12 and discharged from the discharge port D2 to a discharge flow passage (not shown) outside the machine. By the way, in this compressor, in order to prevent the lubricating oil injected into the bearing portion 31 of the speed increasing device 13 from passing through the shaft sealing portion 32 and leaking to the coupling 37 side, an arrow A in FIG. As shown in, the lubricating oil is sucked into the oil tank below the speed increasing device 13 by sucking a small amount of outside air from the coupling 37 side under the atmospheric pressure and forming an air flow toward the bearing portion 31 side. It is supposed to be returned.

Inside the speed-increasing device 13 including the oil tank, the suction air, and oil discharge holes (not shown) of the shaft sealing portions 18 and 22 of the first-stage compressor body 11 and the second-stage compressor body 12 Because of the air flowing in from, the positive pressure is slightly higher than the atmospheric pressure. If this positive pressure is too high, the sealing performance of the labyrinth seal at the location of the input shaft 33 and the labyrinth seals of the shaft sealing portions 18, 22 will deteriorate. Is released to the outside of the machine, thereby lowering the internal pressure of the speed increasing device 13 and preventing the above-mentioned deterioration of the sealing performance.

[0008]

[Problems to be solved by the device]

 In the above-mentioned conventional device, when the performance of the labyrinth seal of the shaft sealing portions 17 and 21 is deteriorated, and only the oil pump in the lubricating oil circulation passage (not shown) is operated before the compressor is operated, the second atmosphere communication is performed. Lubricating oil may leak out of the machine through the hole 24. Since the compressor is an oil-free type, it is necessary to avoid destroying the image that it supplies clean compressed gas. From this point, the leakage of the lubricating oil is undesirable. Is occurring. The present invention has been made to solve the above-mentioned conventional problems, and prevents oil leakage from the atmosphere communication hole to the outside of the machine without deteriorating the performance of the shaft sealing portion, and increases the speed increasing device from the shaft sealing portion. It aims to provide an oil-free screw compressor capable of recovering the lubricating oil in the lower oil tank.

[0009]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the present invention provides an atmosphere communication that communicates at least the inner peripheral surface of a rotor shaft shaft seal portion provided around at least the suction side shaft portion of the shaft portions on both sides of a screw rotor with the atmosphere. An oil-free screw compression machine that has a hole and the uppermost part of the input shaft of the speed-increasing device interposed between the compressor body and the drive part of the screw rotor is lower than the lowermost part of the screw rotor shaft. In the machine, the inner peripheral surface of the input shaft shaft seal portion provided around the input shaft is communicated with the outside of the speed increasing device on the drive unit side, and an acute angle is formed with respect to the input shaft toward the drive unit side. Of the oil return hole, the pipe for communicating the oil return hole with the atmosphere communication hole, and the part from the atmosphere communication hole to the oil return hole at a position higher than this position. It is formed by providing a pressure equalizing hole that communicates with the atmosphere. .

[0010]

[Action]

 With the configuration as described above, the lubricating oil is guided from the rotor shaft seal portion into the speed increasing device by the ejecting effect due to the air flow toward the inside of the speed increase device in the inner peripheral portion of the input shaft shaft seal portion. At the same time, a small amount of air can be sent to the rotor shaft seal portion by the pressure equalizing hole.

[0011]

【Example】

 Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an oil-free screw compressor according to the present invention. The parts common to those of the compressor shown in FIGS. In the present embodiment, the inner peripheral surface of the shaft sealing portion 32 provided around the input shaft 33 is communicated with the outside of the speed increasing device 13 on the drive unit side, and is directed toward the drive unit side with respect to the input shaft 33. An oil return hole 1 having an acute angle, a pipe 2 for communicating the oil return hole 1 with the second atmosphere communication hole 24, and an intermediate portion of the pipe 2 for communicating with the atmosphere at a position higher than the intermediate portion. That is, the pressure equalizing hole 3 is provided upward from the intermediate portion.

With this structure, the uppermost part of the input shaft 33 is positioned lower than the lowermost parts of the shafts of the screw rotors F1 and M1 and the lowermost parts of the shafts of the screw rotors F2 and M2. In the compressor, the lubricating oil from the shaft sealing portion 17 is introduced into the speed increasing device 13 through the pipe 2 due to the ejecting effect of the air flow toward the inside of the speed increasing device 13 in the inner peripheral portion of the shaft sealing portion 32. Therefore, the lubricating oil will not leak out of the machine. That is, the lubricating oil is collected in the oil tank in the speed increasing device. Further, the pressure equalizing hole 3 is formed upward so as to prevent the lubricating oil from leaking from here. Further, the pressure equalizing hole 3 enables a small amount of air to be sent to the shaft sealing portion 17, that is, the labyrinth seal of the shaft sealing portion 17 sucks a small amount of air from the second atmosphere communication hole 24. As a result, an air flow is formed on the bearing portion 15 side, which makes it possible to maintain the shaft sealing performance. Although FIG. 1 shows the first-stage compressor body 11, in the present embodiment, the second-stage compressor body 12 is also formed by providing oil return holes, pipes, and pressure equalizing holes in the same manner as above. The same effect as described above is produced. The parts not shown in FIG. 1 are substantially the same as those of the device shown in FIGS.

Although the two-stage compressor has been described in the above embodiment, the present invention is not limited to this, and the uppermost part of the input shaft of the speed increasing device is located lower than the lowermost part of the screw rotor shaft. The compressor formed as described above includes both a single-stage compressor and a multi-stage compressor having three or more stages. Further, in the above-described embodiment, the compressor provided with the two communication holes of the first atmosphere communication hole 23 and the second atmosphere communication hole 24 in the shaft sealing portion has been described, but the present invention has one atmosphere communication hole. It also includes a compressor equipped with only. Further, when the air communication hole is also provided in the shaft seal portion on the discharge side of the compressor body, the oil return hole, the pipe, and the pressure equalizing hole similar to those in the above-described embodiment may be provided.

[0014]

[Effect of device]

 As is apparent from the above description, according to the present invention, among the shaft portions on both sides of the screw rotor, at least the inner peripheral surface of the rotor shaft shaft sealing portion provided around the suction side shaft portion is exposed to the atmosphere. An oil-free screw provided with a communication hole, and the uppermost part of the input shaft of the speed increasing device interposed between the compressor body and the driving part of the screw rotor is located lower than the lowermost part of the screw rotor shaft. In the compressor, the inner peripheral surface of the input shaft shaft sealing portion provided around the input shaft is communicated with the outside of the speed increasing device on the drive unit side, and toward the drive unit side with respect to the input shaft. The oil return hole that forms an acute angle, the pipe that connects the oil return hole with the atmosphere communication hole, and the part from the atmosphere communication hole to the oil return hole, whichever is higher than this position. Formed by providing a pressure equalization hole that communicates with the atmosphere. And Aru. Therefore, due to the ejecting effect due to the air flow toward the inside of the speed increasing device at the inner peripheral portion of the input shaft shaft sealing part, the lubricating oil is guided from the rotor shaft shaft sealing part into the speed increasing device through the piping. Collected in the oil tank, the lubricating oil will not leak out of the machine. In addition, the pressure equalizing hole is formed upward, and it is possible to prevent the lubricating oil from leaking from this and also to send a small amount of air to the rotor shaft seal portion by this pressure equalizing hole. That is, the rotor shaft shaft seal part sucks a small amount of air from the atmosphere communication hole and forms an air flow on the bearing part side, which is effective in maintaining the shaft seal performance. .

[Brief description of drawings]

FIG. 1 is a partial vertical cross-sectional view of an oil-free screw compressor according to the present invention.

FIG. 2 is a cross-sectional view of a conventional oil-free screw compressor.

3 is a partially enlarged vertical sectional view showing a suction side of a first stage compressor body of the compressor shown in FIG.

FIG. 4 is a diagram showing a positional relationship between shaft centers of respective shafts of the compressor shown in FIG.

5 is a partially enlarged vertical sectional view showing an input shaft portion of the speed increasing device for the compressor shown in FIG.

[Explanation of symbols]

 1 Oil Return Hole 2 Piping 3 Pressure Equalizing Hole 11 First Stage Compressor Body 12 Second Stage Compressor Body 13 Speed Booster 17,21 Shaft Seal 33 Input Shaft F1, D1, F2, D2 Screw Rotor

Claims (1)

[Scope of utility model registration request] 1. A compressor body, comprising at least an atmosphere communication hole for communicating at least an inner peripheral surface of a rotor shaft shaft sealing portion provided around a suction side shaft portion of shaft portions on both sides of a screw rotor with the atmosphere. In the oil-free screw compressor in which the uppermost part of the input shaft of the speed increasing device interposed between the screw rotor and the drive part of the screw rotor is lower than the lowermost part of the shaft of the screw rotor, An inner peripheral surface of an input shaft shaft seal portion provided to the outside of the speed increasing device on the drive portion side, and an oil return hole forming an acute angle with the input shaft toward the drive portion side; A pipe for communicating the oil return hole with the atmosphere communication hole, and a pressure equalizing hole for communicating any part of the portion from the atmosphere communication hole to the oil return hole to the atmosphere at a position higher than this position. Oil-free characterized by being provided and formed Screw compressor.