JP3771749B2 - Oil-free compressor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an oil-free compressor driven via a speed increasing gear train.
[0002]
[Prior art]
Conventionally, as shown in FIG. 4, an oil-free screw compression in which a gear box 54 containing a speed increasing gear train 53 is interposed between a compressor main body 51 and a motor 52 which is a drive portion of the compressor main body 51. The machine 3 is known (Japanese Patent No. 2791204). The lower part of the gear box 54 is an oil reservoir 55, from which oil is injected into the bearing portion and the gear train 53 in the compressor body 51 so that the oil is returned to the oil reservoir 55. It has become. From the upper part of the gear box 54, an exhaust passage 59 is provided with an oil separator / recovery unit 56, a vacuum ejector 57 and an electromagnetic valve 58. A filter element 60 for gas-liquid separation is accommodated in the oil separation / recovery device 56, and a relief valve 61 is provided in a portion of the exhaust passage 59 on the primary side of the oil separation / recovery device 56.
[0003]
During the operation of the compressor, the upper space of the oil reservoir 55 is filled with oil mist. Further, since there is compressed air that leaks from the shaft seal portion in the compressor main body 51 into the gear box 54, it is necessary to release this compressed air to the outside in order to suppress an increase in pressure in the gear box 54. If there is no escape space for the compressed air, oil enters the rotor chamber together with the compressed air from the gear box 54 through the shaft seal portion in the compressor main body 51. For this reason, compressed air and oil mist in the upper space of the oil reservoir 55 are released by the exhaust passage 59. The filter element 60 separates the compressed air and the oil, and the oil is temporarily stored in the lower portion of the oil separator / collector 56, while the compressed air separated from the oil is sent out through the vacuum ejector 57 and the electromagnetic valve 58. ing. However, if the filter element 60 is clogged and the pressure loss here increases, the exhaust passage 59 does not function, and the pressure in the gear box 54 increases.
For this reason, this compressor is provided with a vacuum ejector 57 that receives supply of compressed air, and even if the filter element 60 is clogged, the vacuum ejector 57 promotes exhaust.
[0004]
[Problems to be solved by the invention]
In the case of the oil-free screw compressor described above, since compressed air is used in the vacuum ejector 57, energy loss is caused. Further, the vacuum ejector 57 has a problem of poor reliability such as clogging. Furthermore, when the filter element 60 is clogged to the extent that the vacuum ejector 57 cannot compensate, that is, beyond the capacity of the vacuum ejector 57, the pressure in the gear box 54 rises, and the compressor body from the gear box 54 rises. Oil enters the rotor chamber together with the compressed air through the shaft seal in 51. Such a situation may cause problems such as the occurrence of galling between the rotors due to oil compression in the compressor main body 51 and the mixing of oil into the discharged compressed air. Furthermore, in order to prevent this, the filter element 60 has to be frequently replaced, and there is a problem that maintenance is troublesome.
The present invention has been made as a problem to eliminate the conventional problems that do斯, recovered almost completely capture the oil mist within the gearbox, escape only air to the outside, the pressure in the gearbox It is an object of the present invention to provide an oil-free compressor that can prevent the occurrence of an abnormal rise of the engine and can reduce maintenance work.
[0005]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides at least a pair of male and female rotors that mesh with each other, a casing that houses the rotor, a bearing portion that supports the rotor shaft of the rotor, and a rotor end face side from the bearing portion. A gear box that houses a speed increasing gear train and that has an exhaust passage extending from the upper part is interposed between a compressor body constituted by a shaft seal portion and a motor that is a drive portion of the compressor body. An oil-free compressor in which oil stored in the lower portion of the gear box is injected into the bearing portion and the gear train and returned to the original position is provided with a flow passage for allowing fluid to pass through the oil box. An electric particulate trap provided with a long electrode in the direction along the flow path in the path includes the exhaust flow path, and an air flow inlet and an air flow outlet for discharging air by a fan. Machine body, the above motor And is provided outside the package that houses the gearbox, and passes through the shaft seal portion and the casing to communicate between the space between the shaft seal portion and the rotor shaft and the space outside the casing. The space in which the hole is formed and the flow path on the secondary side of the electric particle trap is communicated with the space outside the casing is the same space inside the package .
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings.
1, 2 and 3, which shows an oil-free compressor 1 according to the present invention, in particular FIG. 3 is a enlarged sectional view of the compressor surrounding body including a characteristic portion of a compressor according to the present invention .
The oil-free compressor 1 includes a compressor body 14 and a motor 15 that is a drive unit of the compressor body 14 in a package 13 having an air inlet 12 and an air outlet 12 through which air flows out by a fan 12a . It is a package type which is interposed between the two and accommodates the speed increasing gear train 16 and a gear box 18 having an exhaust passage 17 extending from the top. The compressor body 14 is composed of a pair of male and female rotors provided in a casing 30, and in one rotor, for example, in FIG. 3, the male rotor 31 is driven by a motor shaft via the speed increasing gear train 16 by the rotor shaft. 15 is connected. The pair of male and female rotors are supported by bearing portions 32 disposed on the end surfaces of the respective rotors, and shaft seal portions 33 are provided at positions closer to the end surfaces of the rotor than the bearing portions 32. The shaft sealing portion 33 and the casing 30 are provided with a conduction hole 34, and a space that exists between the shaft sealing portion 33 and the rotor shaft in the conduction hole 34 and the casing of the compressor main body 14. 30 is configured to be electrically connected to the outside, that is, the space in the package 13 here.
The lower part of the gear box 18 is an oil reservoir 19, and the oil in the oil reservoir 19 is supplied to the gear train 16 and the bearing in the compressor main body 14, and then collected in the oil reservoir 19. Used cyclically.
[0007]
The exhaust passage 17 is provided with a known electric particulate trap 20 (Japanese Patent Laid-Open No. 10-235224) outside the package 13 , where it flows from the gear box 18 into the exhaust passage 17. The coming oil mist is captured and recovered, and the air in the gear box 18 is made clean through the exhaust passage 17 to escape to the outside, that is, the package 13 here.
As shown in FIG. 2, the electric particulate trap 20 in the present embodiment divides the cross section of the exhaust passage 17 into a large number of small passages 21 that allow fluid to pass upward, and is a cell that is in a positive potential state. Each of the cell groups 22 has a structure in which the electrode pins 23 that are arranged apart from the wall portion of the small flow path 21 and are in a negative potential state are arranged in two stages. . In addition, an auxiliary electrode 24 that is in a position before reaching the cell group 22 and on the primary side of the cell group 22 and is in a negative potential state is disposed, and on the primary side of the auxiliary electrode 24 A known metallic special filter 25 for capturing mist particles of 1 μm or more is arranged.
[0008]
Mist fine particles of less than 1 μm are captured by the cell group 22, the electrode pin 23 and the auxiliary electrode 24, and are collected from the lower drain collection port 26. And the air which became a clean state as a result of the said capture | acquisition and collection | recovery of oil mist is sent from the fan 27 of the upper part. The electrode pins 23 which are the main oil mist charging or capturing electrodes are long and many, but are arranged in the direction along the small flow path 21. Does not obstruct fluid flow.
[0009]
As described above, in the oil-free compressor 1, the electric particulate trap 20 is provided in the exhaust passage 17 of the gear box 18 and outside the package 13, thereby maintaining a good flow of air. It captures and collects oil mist efficiently. Further, the maintenance such as the replacement of the filter element described above is not necessary in the electric particle trap 20, and the maintenance work is reduced.
[0010]
The shaft seal portion 33 of the compressor main body 14 is shown in FIG. 3 as a so-called visco seal. The shaft seal portion 33 is formed with a screw-shaped processed bisco seal portion 33a on the inner peripheral portion close to the bearing portion 32. Further, as described above, the end portion of the bisco seal portion 33a is the conduction hole 34. And communicates with the outside of the casing 30, that is, the space inside the package 13 here. Further, the flow path 17 a on the secondary side of the electric particulate trap 20 is configured to communicate with the space in the package 13. Further, the space outside the casing of the compressor body 14 is also a space in the package 13 and is the same as the space where the flow path 17a on the secondary side of the electric particle trap is communicated.
[0011]
The oil stored in the lower part of the gear box 18 is supplied to the bearing portion 32 through the oil supply path 35, and the oil is returned to the gear box 18 again through the oil discharge path 36. In this case, there is a concern that the oil supplied to the bearing portion 32 may leak into the rotor due to a suction force that exceeds the shaft sealing effect of the shaft sealing portion 33 that occurs particularly during an unloading operation. Normally, in order to prevent external oil or the like from entering the rotor side of the compressor, the pressure applied to the rotor side is P1 and the pressure applied to the non-rotor side is P2 at the compressor shaft seal. A shaft seal function that does not allow fluid conduction even when a pressure difference larger than the differential pressure P3 = P2−P1 is required. In this compressor, the pressure P1 applied to the rotor side of the shaft seal portion corresponds to the rotor side end portion (I) of the visco seal portion 33a and consequently the pressure of the conduction hole 34. Further, the pressure P2 applied to the shaft sealing portion on the side opposite to the rotor is the other rotor side end portion (II) of the visco seal portion 33a, and thus corresponds to the pressure inside the gear box 18.
[0012]
The conduction hole 34 communicates with the package 13, and the electric particulate trap 20 communicated with the gear box 18 on the primary side communicates with the package 13 on the secondary side. Since the pressure loss in the electric particulate trap 20 is very small, by adopting the above configuration, when the pressure in the space in the package 13 is P4, both P1 and P2 are close to P4, The differential pressure P3 is an extremely low value. Therefore, if the shaft seal portion is configured to have a predetermined shaft seal function such as a so-called visco seal, a sufficient shaft seal effect can be obtained, and the rotor side of the compressor such as oil that is concerned The situation of mixing in can be avoided.
[0013]
In FIG. 3, the shaft seal portion is composed only of a Bisco seal, and the conductive hole is provided only at one location, but the present invention is not limited to this. Another shaft sealing means seal ring is arranged between the visco seal and the rotor, and the space between the seal ring and the rotor shaft communicates with the space in the package. A hole may be formed.
[0014]
【The invention's effect】
As is apparent from the above description, according to the present invention, at least a pair of male and female rotors that mesh with each other, a casing that houses the rotor, a bearing portion that supports the rotor shaft of the rotor, and a rotor end surface side from the bearing portion. A gear that accommodates a speed increasing gear train and has an exhaust passage extending from an upper portion between a compressor main body constituted by a shaft seal portion disposed and a motor that is a driving portion of the compressor main body. In an oil-free compressor that interposes a box and injects oil accumulated in the lower part of the gear box into the bearing portion and the gear train and returns the oil to the original state, the oil-free compressor includes a flow path through which fluid passes. An electric particulate trap provided with an electrode elongated in the direction along the flow path in the flow path is provided with the air flow path and an air flow outlet through which air flows out by a fan. , The compressor body, The motor and the gear box are provided outside the package, and pass through the shaft seal portion and the casing to communicate the space between the shaft seal portion and the rotor shaft with the space outside the casing. The space through which the secondary particles of the electric particle trap are communicated and the space outside the casing are the same space inside the package .
[0015]
For this reason, while maintaining a good flow of air in the exhaust passage of the gear box, oil mist can be captured and recovered with high efficiency, and the normal function of the shaft seal in the compressor body can be maintained. This eliminates the need for maintenance such as replacement of the filter element for oil removal, thereby reducing the maintenance effort. Moreover, since the conduction hole is provided, there is an effect that the function of the shaft seal portion in the compressor body can be further protected.
[Brief description of the drawings]
FIG. 1 is a diagram showing an overall configuration of an oil-free compressor according to the present invention.
FIG. 2 is a cross-sectional view showing an electric particulate trap in the compressor shown in FIG.
FIG. 3 is an enlarged cross-sectional view around the compressor body in the compressor according to the present invention.
FIG. 4 is a diagram showing an overall configuration of a conventional oil-free screw compressor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Oil free compressor 11 Air inflow port 12 Air outflow port 12a Fan 13 Package 14 Compressor main body 15 Motor 16 Speed increasing gear train 17, 17a Exhaust flow path 18 Gear box 19 Oil reservoir 20 Electric particle trap 21 Small Flow path 22 Cell group 23 Electrode pin 24 Auxiliary electrode 30 Casing 31 Male rotor 32 Bearing part 33 Shaft seal part 34 Conduction hole 35 Oil supply path 36 Oil discharge path

Claims (1)

Compressor body composed of at least a pair of male and female rotors that mesh with each other, a casing that accommodates the rotor, a bearing portion that supports the rotor shaft of the rotor, and a shaft sealing portion that is disposed closer to the rotor end surface than the bearing portion. And a motor that is a drive unit of the compressor body, a gear box that houses a speed increasing gear train and has an exhaust passage extending from the upper part is interposed, and oil accumulated in the lower part of the gear box is In an oil-free compressor that is injected into the bearing portion and the gear train and returned to the original state,
An electric particulate trap provided with a flow path for allowing fluid to pass through and having an electrode elongated in the direction along the flow path in the flow path is provided in the exhaust flow path, the air inlet and the fan. An air outlet for allowing air to flow out, and provided outside the package containing the compressor body, the motor and the gear box,
A conduction hole is formed through the shaft sealing portion and the casing so as to communicate the space between the shaft sealing portion and the rotor shaft and the space outside the casing. An oil-free compressor characterized in that a space communicating with a flow path on the side and a space outside the casing are the same space inside the package .

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