JP6511321B2 - Refueling displacement compressor - Google Patents

Description

The present invention relates to a positive displacement compressor provided with a cooling flow passage in a motor casing and having a function of injecting a liquid from the outside into a compression chamber and a bearing.

  FIG. 5 shows the structure of the compressor body 1 in a conventional oil-filled displacement-type compressor. As an example of the compressor body 1, the compression mechanism is a screw compressor. The compressor body 1 has a twisted lobe, and a male rotor 2 and a female rotor 3 (not shown) which rotate by meshing with each other, a casing 4 for housing them, and a suction for rotatably supporting both male and female rotors. It comprises a side bearing 5 and a discharge side bearing 6 and a shaft sealing part 7 such as an oil seal or a mechanical seal. Generally, the male rotor 2 is connected to a motor 8 which is a rotational drive source via a rotor shaft at the suction side end (left side in the drawing).

  The male rotor 2 rotationally driven by the motor 8 rotationally drives the female rotor 3 to expand and contract an operating space 9 formed by the tooth grooves of the male and female rotors and the inner wall surface of the casing 4 surrounding it. A fluid such as air is sucked from the suction port 10, compressed to a predetermined pressure, and then discharged from the discharge flow path 11. Further, the working space 9, the suction side bearing 5 and the discharge side bearing 6 are lubricated from the outside of the compressor main body 1 through the oil supply hole 12, the suction side bearing oil supply hole 13 and the discharge side bearing oil supply hole 14 respectively. Oil is injected.

  FIG. 6 shows the external path of the lubricating oil supplied to the compressor body 1. The lubricating oil path is constituted by the compressor body 1, the centrifugal separator 15, the oil cooler 16, accessories 17 such as a filter and a reverse valve, and oil pipes 18 connecting them. In the compressed gas discharged from the compressor main body 1, lubricating oil injected from the outside into the compressor is mixed. The lubricating oil mixed in the compressed gas is separated from the compressed gas by the centrifuge 15 and cooled by the oil cooler 16 and then branched via the accessory 17 to again operate the working space 9 inside the compressor body 1. , And the suction side bearing 5 and the discharge side bearing 6. The branch point of the lubricating oil path is not limited to the outside of the compressor main body 1 as shown in the figure, but includes one that branches inside the casing 4 of the compressor main body 1.

  The purpose of the oil supply to the working space 9 is diverse, such as sealing of the inner space, cooling of the gas in the compression process, or lubrication of the sliding male and female rotors. On the other hand, the purpose of the oil supply to the suction side bearing 5 and the discharge side bearing 6 is their respective lubrication. Therefore, in order to improve the compression efficiency, it is effective to lower the oil supply temperature to promote the heat release of the compressed gas to the lubricating oil, or to increase the viscosity of the lubricating oil interposed in the gap to prevent the oil film breakage. Conceivable. However, if the oil temperature is lowered to improve the compression efficiency, the viscosity of the lubricating oil supplied to the suction side bearing 5 and the discharge side bearing 6 also increases, so the stirring loss motive power of the lubricating oil in each increases. It becomes a factor that hinders the improvement of the efficiency of the machine body 1. Therefore, Patent Document 1 describes a method for raising the oil supply temperature for the suction side bearing 5 or the discharge side bearing 6 more than the oil supply temperature for the working space 9.

  Further, in Patent Document 2, the oil flow path is branched on the downstream side of the oil cooler, one is directly in communication with the working space, and the other is in communication with the suction side or the discharge side bearing chamber via the inside of the motor casing. Is described. With this structure, it is conceivable that the temperature of the lubricating oil absorbed by the motor, which generates heat inside the motor casing, rises and the oil is fed to the bearing at a temperature higher than the temperature of the lubricating oil supplied to the working space.

JP, 2013-241920, A JP 2005-69062 A

  In the oil type screw compressor described in Patent Document 1, the lubricating oil passage communicating with the bearing bypasses the oil cooler, thereby comparing with the temperature of the lubricating oil supplied to the working space via the oil cooler. The temperature of the lubricating oil supplied to the bearings becomes high. By this, even when the temperature of the lubricating oil supplied to the working space is lowered for the purpose of improving the compression efficiency, the stirring loss power in the bearing is increased by maintaining the temperature of the lubricating oil supplied to the bearing high. It is considered possible to realize a highly efficient compressor. However, a valve mechanism intervenes in the lubricating oil passage communicating with the bearing, which increases the pressure loss in the oil feeding passage. For example, immediately after start-up of the compressor, the temperature of the lubricating oil is significantly lower than that during operation, and there is a concern that a sufficient amount of lubricating oil may not be supplied to the bearing when the viscosity is high. In addition, as the control mechanism becomes complicated, there is a concern that hunting may occur in the valve mechanism itself or the controller of the cooling fan of the oil cooler.

  In the oil-cooled screw compressor described in Patent Document 2, since the lubricating oil directly flows into the motor casing, there is a concern that the loss power due to the stirring of the lubricating oil by the rotor of the motor may increase. In addition, there is a concern that the lubricating oil inside the compressor flows back into the motor casing after operation is stopped and is accumulated in the motor casing, leading to deterioration of internal parts of the motor and a marked increase in starting torque.

The object of the present invention is to lubricate the working space of the compressor body without significantly increasing the pressure loss due to the addition of a valve mechanism or the like to the conventional lubricating oil path and without flowing the lubricating oil into the motor casing. By raising the oil supply temperature of the bearing from the temperature, even when the oil supply temperature is lowered to improve the compression efficiency, it is possible to realize a highly efficient compressor by minimizing the stirring loss in the bearing.

In order to achieve the above object, according to the present invention, in a positive displacement compressor provided with a cooling flow passage in a motor casing and having a function of supplying liquid to the compression chamber and bearings from the outside, lubricating oil is supplied to the compressor bearings The cooling passage of the motor casing is in communication with the upstream side of the fueling hole.

According to the present invention, the lubricating oil supplied to the bearing exchanges heat with the motor on the upstream side, whereby the oiling temperature to the bearing becomes higher than the oiling temperature to the working space. Therefore, even when the oil supply temperature to the working space is lowered for the purpose of improving the compression efficiency, the oil supply temperature to the bearing is relatively high, that is, the low viscosity is maintained, and the lubricating oil agitation loss in the bearing is minimized. Is possible. This makes it possible to increase the efficiency of the oil type displacement compressor.

It is a vertical sectional view of a screw compressor in a 1st example of the present invention. It is a lubricating oil path in 1st Example of this invention. It is a vertical sectional view of a screw compressor in a 2nd example of the present invention. It is a vertical sectional view of a screw compressor in a 3rd example of the present invention. It is a vertical sectional view of a common screw compressor. It is a lubricating oil path of a common screw compressor.

  Hereinafter, the present invention will be described in detail using the drawings.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. The present embodiment relates to a screw type air compressor which compresses air. Further, since the configuration is the same as the configuration shown in FIGS. 5 and 6, the same reference numerals are given and the description is omitted. The shaft seal part 7 is a mechanical seal.

  The present embodiment differs from the embodiment in FIG. 5 in that the casing of the motor 8 is provided with an oil cooling jacket 19 serving as an oil passage for lubrication, and the connection piping 20 for the oil cooling jacket 19 and the oil piping 18 is provided. And, the oil cooling jacket 19 is connected to the oil supply holes 13 and 14 of the suction side bearing 5 and the discharge side bearing 6 respectively.

  The lubricating oil path in the present embodiment will be described with reference to FIG. On the downstream side of the auxiliary machine 17, the oil pipe branches, and one is connected to the oil supply hole 12. The other communicates with the suction side bearing oil supply hole 13 and the discharge side bearing oil supply hole 14 via the oil cooling jacket 19 of the motor 8. Therefore, since the lubricating oil supplied to the suction side bearing 5 and the discharge side bearing 6 absorbs heat from the motor 8 on the upstream side, the oiling temperature thereof is higher than the temperature of the lubricating oil supplied to the working space 9 . That is, even if the cooling capacity of the cooler is increased and the temperature of the lubricating oil supplied to the working space is lowered for the purpose of improving the compression efficiency, the lubricating oil supplied to the bearing exchanges heat with the motor Because the temperature rises due to the viscosity, the viscosity does not increase more than necessary. As described above, by minimizing the stirring loss power in the bearing, it is possible to realize a screw compressor that is effective for energy saving of the compressor.

  In this embodiment, the bypass channel 21 connecting the upstream side of the oil cooler 16 with the suction side bearing oil supply hole 13 and the discharge side bearing oil supply hole 14 and the branch point of the bypass flow path 21 and the oil pipe 18 are located. The valve mechanism 22 is provided. If the temperature of the lubricating oil is significantly lower than that during operation, such as immediately after the orbit of the compressor body 1, the valve mechanism 22 opens the bypass passage 21 and the lubricating oil is oil cooler 16, auxiliary machine 17, And it bypasses a flow path with a large flow resistance such as the oil cooling jacket 19 and flows into the suction side bearing oil supply hole 13 and the discharge side bearing oil supply hole 14. As a result, regardless of the operating state, it is possible to stably lubricate the suction side bearing 5 and the discharge side bearing 6.

Further, the installation state of the screw compressor described in the present embodiment is effective not only in the horizontal installation as shown in FIG. 1 but also in the case where the axis of the male rotor 2 is vertically arranged.

  Hereinafter, a second embodiment of the present invention will be described with reference to FIG. The present embodiment relates to a screw type air compressor as in the first embodiment, and the same parts as the first embodiment will be described with the same symbols.

The present embodiment differs from FIG. 1 in that the lubricating oil after lubricating the suction side bearing 5 and the discharge side bearing 6 is communicated with the working space 9 after the suction is completed via the lubricating oil recovery hole 23. is there. The dashed line in the figure is the suction port 24 on the outer peripheral surface of the male rotor 2. The working space 9 located on the compression side (right side of the drawing) from the suction port has already closed the suction process and is in the compression process, so the space is closed. Therefore, the lubricating oil supplied to the working space 9 does not scatter in the vicinity of the suction port 10. As a result, the lubricating oil whose temperature has risen by the cooling of the motor 8 and the lubrication of the suction side bearing 5 and the discharge side bearing 6 scatters in the vicinity of the suction port 10 and heats up the intake air by heat exchange with the air flowing from the suction port. It becomes possible to suppress. As described above, it is possible to suppress the intake air heating phenomenon and realize a screw compressor that is effective for increasing the air flow rate.

  Hereinafter, a third embodiment of the present invention will be described with reference to FIG. The present embodiment relates to a screw-type air compressor as in the second embodiment, and the same parts as the second embodiment will be described with the same symbols.

  The present embodiment differs from FIG. 3 in that a second mechanical seal 25 is provided between the suction side bearing 5 and the male rotor 2 and the female rotor 3. As a result, the lubricating oil supplied to the suction side bearing 5 flows into the inside of the compressor body 1 from the gap between the casing 4 of the compressor body 1 and the shafts of the male rotor 2 and the female rotor 3 and in the vicinity of the suction port 10 The scattering phenomenon is suppressed. Therefore, compared with the screw compressor described in the second embodiment, it is possible to further suppress the intake air heating phenomenon and realize a screw compressor that is more effective to increase the air flow rate.

The effect of the present embodiment is the same even if the mechanical seal 7 and the second mechanical seal 25 are replaced with other shaft seal parts such as an oil seal, a magnetic fluid seal, or a labyrinth seal.

Reference Signs List 1 compressor body 2 male rotor 3 female rotor 4 casing 5 suction side bearing 6 discharge side bearing 7 shaft sealing part 8 motor 9 operation space 10 suction port 11 discharge flow path 12 oiling Hole 13 ... Suction side bearing oiling hole 14 ... Discharge side bearing oiling hole 15 ... Centrifuge 16 ... Oil cooler 17 ... Auxiliary machine 18 ... Oil piping 19 ... Oil cold jacket 20 ... Connection piping 21 ... Bypass flow path 22 ... Valve Mechanism 23 ... lubricating oil recovery hole 24 ... suction port 25 ... second mechanical seal

Claims (3)

A cooling flow path to the motor casing, a positive displacement compressor having a function of supplying a lubricating oil from outside the working space and the bearings of the compressor body,
The lubricating oil passage branches into a passage connecting to a first oil supply hole for supplying the lubricating oil to the working space and a second oil supply hole for supplying the lubricating oil to the bearing.
Passage to be connected to the second oil supply hole, the cooling passages of the motor casing a downstream side of the branch upstream of the second oil supply hole is communicated,
A flow path connected to the first oil supply hole does not communicate with a cooling flow path of the motor casing on the downstream side of the branch . The displacement compressor according to claim 1 , wherein
The lubricating oil channel is provided with a valve mechanism that can be switched to the bypass channel,
When the temperature of the lubricating oil is low, the bypass flow passage not in communication with the cooling flow passage of the motor casing is connected to the second oil supply hole instead of the flow passage connected to the second oil supply hole And a lubricating oil is supplied to the bearing . A displacement type compressor according to claim 1 or claim 2, characterized in that on either side of the bearing located between the compressor body and motor, comprising a shaft seal part to prevent the lubricating oil entering for each With a positive displacement compressor.

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